WorldWideScience

Sample records for action potential characteristics

  1. 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.

  2. 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.

  3. 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.

  4. 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...

  5. 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...

  6. ADVERGAMES: CHARACTERISTICS, LIMITATIONS AND POTENTIAL

    Directory of Open Access Journals (Sweden)

    Gurau Calin

    2010-07-01

    Full Text Available Advergames represent a new advertising concept that uses Internet technology to implement viral marketing campaigns. Despite the potential of this interactive advertising method, very few academic studies have been initiated to investigate the characteristics of advergames, and their influence on consumers’ perceptions and behaviour. Using secondary data, this paper attempts to evaluate the characteristics of effective advergames, and to analyse the effect of advergames on players’ perceptions and behaviour.

  7. 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.

  8. 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.

  9. 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…

  10. 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...

  11. Characteristics of potential repository wastes

    International Nuclear Information System (INIS)

    This report presents the results of a fully documented peer review of DOE/RW-0184, Rev. 1, ''Characteristics of Potential Repository Wastes''. The peer review was chaired and administered by oak Ridge National Laboratory (ORNL) for the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM) and was conducted in accordance with OCRWM QA procedure QAAP 3.3 ''Peer Review'' for the purpose of quailing the document for use in OCRWM quality-affecting work. The peer reviewers selected represent a wide range of experience and knowledge particularly suitable for evaluating the subject matter. A total of 596 formal comments were documented by the seven peer review panels, and all were successfully resolved. The peers reached the conclusion that DOE/RW-0184, Rev. 1, is quality determined and suitable for use in quality-affecting work

  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. Characteristics of complaints resulting in disciplinary actions against Danish GPs

    DEFF Research Database (Denmark)

    Birkeland, Søren; Christensen, René dePont; Damsbo, Niels;

    2013-01-01

    The risk of being disciplined in connection with a complaint case causes distress to most general practitioners. The present study examined the characteristics of complaint cases resulting in disciplinary action.......The risk of being disciplined in connection with a complaint case causes distress to most general practitioners. The present study examined the characteristics of complaint cases resulting in disciplinary action....

  14. 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...

  15. 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...

  16. 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.

  17. The Characteristics of Action Research in Music Education

    Science.gov (United States)

    Cain, Tim

    2008-01-01

    This review article discusses the use of action research in music education and its potential for producing knowledge and improving practice. The discussion is situated in an analysis of action research studies in music education. The review demonstrates that action research in music education focuses on a wide variety of subject matter,…

  18. 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.…

  19. The characteristics of action research in music education

    OpenAIRE

    Cain, Tim

    2008-01-01

    This review article discusses the use of action research in music education and its potential for producing knowledge and improving practice. The discussion is situated in an analysis of action research studies in music education. The review demonstrates that action research in music education focuses on a wide variety of subject matter, integrates research and action, is collaborative, grounded in a body of existing knowledge, and leads to powerful learning for the participant...

  20. 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...

  1. 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,...

  2. Dynamin: characteristics, mechanism of action and function.

    Science.gov (United States)

    Wiejak, Jolanta; Wyroba, Elzbieta

    2002-01-01

    Dynamin - a member of the GTP-ase protein family - is essential for many intracellular membrane trafficking events in multiple endocytic processes. The unique biochemical features of dynamin - especially its propensity to assemble - enable severing the nascent vesicles from the membrane. The mechanism of dynamin's action is still a subject of debate - whether it functions as a mechanochemical enzyme or a regulatory GTPase. The GTPase domain of dynamin contains three GTP-binding motifs. This domain is very conservative across the species, including that recently cloned by us in the unicellular eukaryote Paramecium. Dynamin interacts with a number of partners such as endophilin and proteins involved in coordination of endocytosis with motor molecules. A growing body of evidence indicates that dynamin and dynamin-related proteins are involved both in pathology and protection against human diseases. The most interesting are dynamin-like Mx proteins exhibiting antiviral activity.

  3. 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...

  4. 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.

  5. [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

  6. 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...

  7. 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...

  8. 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....

  9. 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.

  10. e-Manufacturing: Characteristics, applications and potentials

    OpenAIRE

    CHENG, K; Bateman, RJ

    2008-01-01

    In this paper, an engineering oriented approach is proposed towards e-manufacturing and its applications. The characteristics and potential of e-manufacturing are presented with a number of application examples developed by the authors’ research group. The advances in e-manufacturing and applications are also highlighted and critically reviewed. The paper concludes with a further discussion on the promises and impact of e-manufacturing technology and philosophy on modern manufacturin...

  11. 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.

  12. 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.

  13. 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...

  14. 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...

  15. 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.

  16. 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…

  17. 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

  18. 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

  19. 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

  20. 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.

  1. Favourability: concept, distinctive characteristics and potential usefulness

    Science.gov (United States)

    Acevedo, Pelayo; Real, Raimundo

    2012-07-01

    The idea of analysing the general favourability for the occurrence of an event was presented in 2006 through a mathematical function. However, even when favourability has been used in species distribution modelling, the conceptual framework of this function is not yet well perceived among many researchers. The present paper is conceived for providing a wider and more in-depth presentation of the idea of favourability; concretely, we aimed to clarify both the concept and the main distinctive characteristics of the favourability function, especially in relation to probability and suitability, the most common outputs in species distribution modelling. As the capabilities of the favourability function go beyond species distribution modelling, we also illustrate its usefulness for different research disciplines for which this function remains unknown. In particular, we stressed that the favourability function has potential to be applied in all the cases where the probability of occurrence of an event is analysed, such as, for example, habitat selection or epidemiological studies.

  2. 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.

  3. 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.

  4. 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.

  5. Action Researchers' Perspectives about the Distinguishing Characteristics of Action Research: A Delphi and Learning Circles Mixed-Methods Study

    Science.gov (United States)

    Rowell, Lonnie L.; Polush, Elena Yu; Riel, Margaret; Bruewer, Aaron

    2015-01-01

    The purpose of this study was to identify distinguishing characteristics of action research within the Action Research Special Interest Group of the American Educational Research Association. The authors sought to delineate the foundational framework endorsed by this community. The study was conducted during January-April 2012 and employed an…

  6. On the Analysis of Recurrence Characteristics at Variable Actions

    Directory of Open Access Journals (Sweden)

    Horea SANDI

    2011-07-01

    Full Text Available The paper is devoted to some methodological problems raised by the analysis of hazards due to variable actions having implications for the risk of damage to structures. The basic recurrence model used is that of Poissonian stochastic processes. The techniques of calibration of specific recurrence characteristics are discussed, adopting a critical point of view versus statistical analyses relying exclusively on data like annual maxima. The adoption of some types of distributions is critically discussed, from the point of view of their compatibility with the Poissonian model referred to. Only the Gumbel and Fréchet distributions are accepted as adequate for the purpose adopted. Starting from their common properties an unbounded family of distributions is proposed. This family makes it possible to adopt calibrations providing an approximation of unlimited closeness to observation samples. The case of a pluri-dimensional characterization of the randomness of observation data is then tackled, considering as an illustrative case the directional statistical analysis of sequences of wind events. Some specific expressions are proposed for the directional analysis, leading to a good approximation of observation samples. A case study relying on the expressions is then presented.

  7. 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.

  8. 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…

  9. 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 ...

  10. 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...

  11. Characteristics of potential repository wastes. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1992-07-01

    This document, and its associated appendices and microcomputer (PC) data bases, constitutes the reference OCRWM data base of physical and radiological characteristics data of radioactive wastes. This Characteristics Data Base (CDB) system includes data on spent nuclear fuel and high-level waste (HLW), which clearly require geologic disposal, and other wastes which may require long-term isolation, such as sealed radioisotope sources. The data base system was developed for OCRWM by the CDB Project at Oak Ridge National Laboratory. Various principal or official sources of these data provided primary information to the CDB Project which then used the ORIGEN2 computer code to calculate radiological properties. The data have been qualified by an OCRWM-sponsored peer review as suitable for quality-affecting work meeting the requirements of OCRWM`s Quality Assurance Program. The wastes characterized in this report include: light-water reactor (LWR) spent fuel and immobilized HLW.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Current-potential characteristics of electrochemical systems

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, V.S.

    1993-07-01

    This dissertation contains investigations in three distinct areas. Chapters 1 and 2 provide an analysis of the effects of electromagnetic phenomena during the initial stages of cell discharge. Chapter 1 includes the solution to Maxwell`s equations for the penetration of the axial component of an electric field into an infinitely long cylindrical conductor. Chapter 2 contains the analysis of the conductor included in a radial circuit. Chapter 3 provides a complete description of the equations that describe the growth of an oxide film. A finite difference program was written to solve the equations. The system investigated is the iron/iron oxide in a basic, aqueous solution. Chapters 4 and 5 include the experimental attempts for replacing formaldehyde with an innocuous reducing agent for electroless deposition. In chapter 4, current-versus-voltage curves are provided for a sodium thiosulfate bath in the presence of a copper disk electrode. Also provided are the cathodic polarization curves of a copper/EDTA bath in the presence of a copper electrode. Chapter 5 contains the experimental results of work done with sodium hypophosphite as a reducing agent. Mixed-potential-versus-time curves for solutions containing various combinations of copper sulfate, nickel chloride, and hypophosphite in the presence of a palladium disk electrode provide an indication of the reducing power of the solutions.

  18. 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. ...

  19. 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.)

  20. 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 ...

  1. 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.

  2. 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...

  3. 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,…

  4. 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...

  5. 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...

  6. 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.

  7. 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...

  8. 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.

  9. 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

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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...

  15. 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

  16. 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.

  17. Wind potential and turbulence characteristics on the site of Lastours

    Energy Technology Data Exchange (ETDEWEB)

    Flori, J.P.

    1987-01-01

    Fine wind acquisition campaign and permanent measurement of mean wind speed and direction were made from June 1985 to October 1986 at Lastours (Aude) on a site of complex topography. Annual mean wind speed at 30 m, potential wind energy and the annual energy output for the Ratier Figeac aerogenerators were calculated. Fine wind characteristics at 3 levels (speed profile, direction fluctuations, turbulence scale and intensity, spectral functions) are described. We observe a high wind potential on the site and that the flow characteristics are mainly influenced by the surroundings macro-roughness.

  18. 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.

  19. Research on the firing characteristics of neurons in child cerebral palsy based on the estimation of motor unit action potential number in electromyography signal%利用EMG运动单位动作电位数目估算法研究痉挛型脑瘫患儿神经元发放特性

    Institute of Scientific and Technical Information of China (English)

    姚博; 杨基海; 陈香; 吴德; 钱玲玲; 周逸峰

    2013-01-01

    Objective The evaluation of dyskinesia and rehabilitation for cerebral - palsy ( CP) patients is of important clinical value. The firing characteristics of motor neurons in child cerebral palsy are studied by means of surface electromyography ( sEMG ) to provide an index for CP patients. Methods The smoothed nonlinear energy operator ( SNEO) algorithm is adopted to estimate the number of motor unit action potential (MUAP)in sEMG collected from CP patients. Then, inter - pulse interval (IPI) of MUAP is achieved. The results are verified by the diagnosis and early research on mean potential duration of healthy male volunteers. Results The results of 14 patients' sEMG signals in different CP levels show that there is a positive correlation between their IPIs and the severity of the disease, which also means the levels of CP dyskinesia, and the differences in various CP levels are significant. Conclusions Experimental results of real CP sEMG signals demonstrate that this method is effective and IPI of MUAP can be used as quantitative index for the evaluation of CP dyskinesia and rehabilitation.%目的 小儿脑瘫患者的运动障碍分级和康复评估具有重要的临床价值.本文利用表面肌电信号对痉挛型脑瘫患儿的运动神经元发放特性进行研究,旨在为脑瘫患儿的运动障碍评估提供一种量化指标.方法 采用平滑非线性能量算子(smoothed nonlinear energy operator,SNEO)算法,对痉挛型脑瘫患儿表面肌电信号中的运动单位动作电位(motor unit action potential,MUAP)数目进行估计,获得MUAP的平均发放间隔(inter-pulse interval,IPI),并根据医生采用的分级结果和健康人MUAP平均发放时限的早期研究结果进行对比验证.结果 对14名不同运动障碍级别脑瘫患者的实验结果显示,其肌电信号MUAP的IPI与他们活动度的级别即运动障碍的程度呈正相关的关系,且具有明显差异.结论 研究结果表明本文方法有效,采用IPI参数能

  20. Segmentation and Classification of Human Actions and Actor Characteristics with 3d Motion Data

    Directory of Open Access Journals (Sweden)

    S. Ali Etemad

    2012-08-01

    Full Text Available In this paper we have used 3D motion capture data with the aim of detecting and classifying specifichuman actions. In addition to recognition of basic action classes, actor styles and characteristics such asgender, age, and energy level have also been subject to classification. We have applied and compared threemain methods: nearest neighbour search, hidden Markov models, and artificial neural networks. Usingthese techniques, we have proposed exhaustive algorithms for detection of actions in a motion piece andsubsequently classifying the segmented actions and respective characteristics of the actors. We have testedthe methods for various sequences and compared the results for a comprehensive evaluation of each of theproposed techniques. Our findings can be largely used for general classification of human motion data formultimedia applications as well as sorting and classifying data sets of human motion data especially thoseacquired using visual marker-based motion capture systems such as the one employed in this research.

  1. 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...

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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...

  9. 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.

  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. 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...

  12. 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...

  13. 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...

  14. 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

  15. 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....

  16. 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...

  17. Expert system characteristics and potential applications in safeguards

    International Nuclear Information System (INIS)

    The general growth of expert, knowledge-based (KB) or rule based systems will significantly increase in the next three to five years. Improvements in computer hardware (speed, reduced size, power) and software (rule based, data based, user interfaces) in recent years are providing the foundations for the growth of expert systems. A byproduct of this growth will undoubtedly be the application of expert systems to various safeguards problems. Characteristics of these expert systems will involve 1) multiple rules governing an outcome, 2) confidence factors on individual variables and rule sets, 3) priority, cost, and risk based rule sets, and 4) the reasoning behind the advice or decision given by the expert system. This paper presents characteristics, structures, and examples of simple rule based systems. Potential application areas for these expert systems may include training, operations, management, designs, evaluations, and specific hardware operation

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. Fully ceramic microencapsulated fuels. Characteristics and potential LWR applications

    International Nuclear Information System (INIS)

    This paper summarizes the characteristics of the fully ceramic microencapsulated (FCM) fuel concept and two potential light water reactor (LWR) applications of FCM fuels: for actinide management and as an accident tolerant fuel (ATF). Recent progress in FCM fuel development includes production of uranium mononitride kernels, fabrication of FCM pellets and pins, and irradiation testing of matrix samples and FCM pellets. Potential applications of FCM fuel in LWRs appear promising based upon studies performed by several organizations; however, further efforts are needed to investigate various design aspects in further detail and explore promising new areas of research such as new fuel pin and assembly designs or alternate materials of interest. Current challenges in FCM fuel development and LWR applications for FCM fuels include low heavy metal fuel loading densities and increased uncertainties in analysis due to several different factors. Overall, LWR FCM concepts appear feasible for both actinide management and as an ATF. (author)

  3. Segmentation and Classification of Human Actions and Actor Characteristics with 3d Motion Data

    Directory of Open Access Journals (Sweden)

    S. Ali Etemad

    2012-07-01

    Full Text Available In this paper we have used 3D motion capture data with the aim of detecting and classifying specific human actions. In addition to recognition of basic action classes, actor styles and characteristics such as gender, age, and energy level have also been subject to classification. We have applied and compared three main methods: nearest neighbour search, hidden Markov models, and artificial neural networks. Using these techniques, we have proposed exhaustive algorithms for detection of actions in a motion piece and subsequently classifying the segmented actions and respective characteristics of the actors. We have tested the methods for various sequences and compared the results for a comprehensive evaluation of each of the proposed techniques. Our findings can be largely used for general classification of human motion data for multimedia applications as well as sorting and classifying data sets of human motion data especially those acquired using visual marker-based motion capture systems such as the one employed in this research.

  4. Action semantics and movement characteristics engage distinct processing streams during the observation of tool use.

    Science.gov (United States)

    Hoeren, Markus; Kaller, Christoph P; Glauche, Volkmar; Vry, Magnus-Sebastian; Rijntjes, Michel; Hamzei, Farsin; Weiller, Cornelius

    2013-08-01

    The cortical motor system follows a modular organization in which different features of executed movements are supported by distinct streams. Accordingly, different levels of action recognition, such as movement characteristics or action semantics may be processed within distinct networks. The present study aimed to differentiate areas related to the analysis of action features involving semantic knowledge from regions concerned with the evaluation of movement characteristics determined by structural object properties. To this end, the assessment of (i) tool-associated actions in relation to semantically, but not functionally inappropriate recipients (factor "Semantics"), and the evaluation of (ii) tool-associated movements performed with awkward versus correct hand postures (factor "Hand") were experimentally manipulated in an fMRI study with an event-related 2 × 2 factorial design. The videos used as stimuli displayed actions performed with the right hand in third-person perspective. Conjunction analysis of all four experimental conditions showed that observing videos depicting tool-related actions compared to rest was associated with widespread bilateral activity within the frontal lobes, inferior and superior parietal lobules, parts of the temporal lobes, as well as the occipital lobes. Viewing actions executed with incorrect compared to correct hand postures (factor "Hand") elicited significantly more activity within right primary sensory cortex (Brodmann area 2) and superior parietal lobule. Conversely, tool-associated actions displayed after semantically incorrect compared to correct recipients elicited higher activation within a left-lateralized network comprising the ventro-lateral prefrontal cortex (VLPFC), parts of the intraparietal sulcus and the angular gyrus (AG), as well as the supplementary motor area (SMA) and pre-SMA. Probabilistic diffusion tensor imaging-based tractography revealed two distinct fiber connections between AG and the frontal

  5. Statistical analysis of characteristics of Infant-Directed-Interaction with respect to action structure

    OpenAIRE

    Peters, Annika

    2008-01-01

    Acoustic packaging, intersensory redundancy, motherese and motionese are the main concepts, which describe how acoustic features and body movements of caretakers are adapted intuitively in adult-child-interaction. This thesis will approach the question,whether feature characteristics highlight certain parts of child-directed actions. The main part focuses on the statistical examination of four features, Eye-Gaze, Intonation, Word, Velocity of Hand Motion of child-directed demonstrations...

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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...

  14. 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

  15. 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

  16. 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

  17. 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.

  18. 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...

  19. 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

  20. 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…

  1. 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

  2. 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....

  3. The characteristics of median nerve compound nerve action potential at different post injury and repair intervals and their correlation with nerve regeneration in rats%大鼠正中神经修复后不同时段的电生理变化与神经再生的相关性分析

    Institute of Scientific and Technical Information of China (English)

    李永平; 劳杰; 赵新; 刘靖波; 田东; 张凯丽; 朱艺

    2011-01-01

    目的 探讨大鼠正中神经切断缝合后的不同时段,其复合神经动作电位(CNAP)与形态学方面的特点及其相关性分析.方法 在大鼠上臂正中神经中段切断缝合后的不同时间点(2、3、4、6、8和12周)进行CNAP检测,随后取正中神经组织进行形态学检查.结果 术后第2周可以记录到CNAP.术后再生神经记录的CNAP幅度比对照组显著减低(P<0.01),波幅下面积(Area)也显著低于对照组(P<0.01),传导速度(CV)显著慢于对照组(P<0.01).术后2~6周的潜伏期(Lat)均比对照组明显延长(P<0.05);术后2~8周刺激强度,即阈强度(THI)和超大刺激强度(SSI)显著低于对照组.CNAP的第一峰波幅(FPA)、峰-峰波幅(PPA)、Area、CV变化趋势为随时间增加而逐渐增高,而其参数Lat、THI、SSI随时间增加而逐渐降低.神经修复后2周缝合口远端已有少量的新生轴突,随着再生时间延长,越来越多的再生轴突延伸至远端.远端记录的CNAP波幅与其有髓神经纤维计数之间有强的正相关(相关系数为0.953).线性回归分析表明,存在线性关系.术后8周髓鞘趋向于成熟.结论 CNAP是早期诊断和评价损伤神经再生程度的良好指标.正常正中神经的CNAP波幅可能与有髓神经纤维的计数呈线性关系.术后第8周,CNAP参数趋向于稳定,神经髓鞘渐趋向于成熟.%Objective To explore the characteristics of compound nerve action potential (CNAP) after rat median nerve transection and repair,and their correlation with neuromorphometry at various time points. Methods The median nerve was transected and sutured at mid-arm level. At various time points from 2 to 12 weeks postoperatively,CNAP recording was performed and the median nerve was harvested for morphological examination. Results CNAP could be recorded at 2 weeks after nerve repair. The CNAP amplitude,the area below the curve (Area) and conduction velocity (CV) of regenerated nerve were significantly lower than those

  4. 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.

  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. Einstein-Hilbert action nontrivially coupled with topological characteristic classes: generating Torsion and Contortion

    CERN Document Server

    Espiro, J Lorca

    2014-01-01

    In this work we consider the effects of coupling characteristic classes to gravity by introducing appropriate operators in the Einstein--Hilbert action. As it is well known, this approach strays from the framework of General Relativity since it results in theories in which torsion can be present. An important point of our approach is that the solutions obtained explicitly carry topological information of the considered space-time manifold. We consider here all the characteristic classes that are consistent with a space-time manifold leading to the definition of an 'effective Cosmological Constant' that inherits topological information. We present analytical solutions for the contortion $1$-form that can be obtained under general conditions in various cases of interest. We show how to use these solutions to study cosmological scenarios that are obtained mainly by selecting a metric and an ideal fluid. We also discuss some of the consequences of these cosmological models over the topological and differential st...

  7. 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....

  8. '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.

  9. 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.

  10. 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...

  11. 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...

  12. An Investigation of the Potential Malignant Characteristics of Endometriosis

    Institute of Scientific and Technical Information of China (English)

    Chengxin Wang; Hongyan Zhou; Xiaonan You; Xiji Shu; Yan Li; Xiaoling Zhao

    2005-01-01

    OBJECTIVE To investigate the potential malignant characteristics and pathogenesis of endometriosis as well as the role of human growth hormone and epidermal growth factor receptor in the pathogenesis of malignant transformation of endometriosis.METHODS The immunohistochemical S-P method was used to examine the expression of human growth hormone and epidermal growth factor receptor in the eutopic and ectopic endometrium of 84 cases of endometriosis.RESULTS The percentage of positive cases of human growth hormone in eutopic and ectopic endometrium was 90.77% (59/65) and 85.71% (72/84) respectively. The percentage of positive cases of epidermal growth factor receptor in eutopic and ectopic endometrium was 81.54% (53/65)and 89.29% (75/84) respectively. The positive rate of epidermal growth factor receptor in ectopic endometrium was higher than that in the eutopic endometrium but without a statistically significant difference (P>0.05).CONCLUSION Endometriosis is caused by multiple factors, which possesses some biologic features of neoplastic tissue such as invasion and metastasis. Both human growth hormone and epidermal growth factor receptor are highly expressed in eutopic and ectopic endometrium, which lead directly or indirectly to the pathogenesis of endometriosis and promote the initiation and malignant transformation of endometriosis.

  13. The Euler characteristic correction to the Kaehler potential - revisited

    CERN Document Server

    Bonetti, Federico

    2016-01-01

    We confirm the leading $\\alpha'^3$ correction to the 4d, $\\mathcal N = 1$ K\\"{a}hler potential of type IIB orientifold compactifications, proportional to the Euler characteristic of the Calabi-Yau threefold (BBHL correction). We present the explicit solution for the $\\alpha'^3$-modified internal background metric in terms of the non-harmonic part of the third Chern form of the leading order Calabi-Yau manifold. The corrected internal manifold is almost Calabi-Yau and admits an $SU(3)$ structure with non-vanishing torsion. We also find that the full ten-dimensional Einstein frame background metric is multiplied by a non-trivial Weyl factor. Performing a Kaluza-Klein reduction on the modified background we derive the $\\alpha'^3$-corrected kinetic terms for the dilaton and the K\\"{a}hler deformations of the internal Calabi-Yau threefold for arbitrary $h^{1,1}$. We analyze these kinetic terms in the 4d, $\\mathcal N = 2$ un-orientifolded theory, confirming the expected correction to the K\\"ahler moduli space prepo...

  14. 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.

  15. 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

  16. 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...

  17. 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

  18. 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

  19. 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

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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 ...

  5. 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...

  6. 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 ...

  7. 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.

  8. 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

  9. 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

  10. The jumping action's indices of female volleyball players and their relation at some somatic characteristics

    Directory of Open Access Journals (Sweden)

    Stech M.

    2010-02-01

    Full Text Available In the paper the results of correlation analysis between of most significance jumping action's indices of high performance polish female volleyball players and their some somatic characteristics (stature, weight and body composition indices: BMI, FATkg, FAT%, FFMkg,FFM%, TBWkg and TBW% are presented. It has been found close correlation between of height of attack jump and stature (r=0,98, weight (r=0,76, FFMkg(r=0,88 and TBWkg (r=0,88. But correlation of height of attack jump with FFM% and TBW% was nonessential. Statistical essential correlation between basic indices of plyometric factor and FAT%, FFM% and TBW% indices (accordingly r = -0,65; 0,65 and 0,66 has been found. The results of the study may be taking into consideration in order to elaboration of effective jumping methods for volleyball players.

  11. 3D Interest Point Detection using Local Surface Characteristics with Application in Action Recognition

    DEFF Research Database (Denmark)

    Holte, Michael Boelstoft

    2014-01-01

    In this paper we address the problem of detecting 3D inter- est points (IPs) using local surface characteristics. We con- tribute to this field by introducing a novel approach for detec- tion of 3D IPs directly on a surface mesh without any require- ments of additional image/video information. The...... proposed Difference-of-Normals (DoN) 3D IP detector operates on the surface mesh, and evaluates the surface structure (curvature) locally (per vertex) in the mesh data. We present an exam- ple of application in action recognition from a sequence of 3-dimensional geometrical data, where local 3D motion de......- scriptors, Histogram of Optical 3D Flow (HOF3D), are ex- tracted from estimated 3D optical flow in the neighborhood of each IP and made view-invariant. Experiments on the pub- licly available i3DPost dataset show promising results....

  12. 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.

  13. 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.

  14. 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...

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. Waste management implications of concentrating slimes - characteristics and potential problems

    International Nuclear Information System (INIS)

    This report describes the geotechnical, geochemical and environmental characteristics of fine-grained uranium tailings (slimes) which may influence both short- and long-term management of slime-enriched uranium tailings impoundments. Properties of slimes are compared and contrasted with those of sand tailings using field and laboratory data primarily from naturally segregated tailings in the Elliot Lake area, Ontario and Northern Saskatchewan uranium-bearing regions of Canada. Key management considerations are included

  20. 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...

  1. 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

  2. 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

  3. 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.

  4. 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.

  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 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.

  6. 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.

  7. 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.

  8. Significance of frost action and surface soil characteristics to wind erosion at Rocky Flats, Colorado. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Caine, N.

    1978-09-01

    This study of the potential links between soil freezing and wind erosion was conducted at Rocky Flats during 4 winters. Most of the study has involved the conditions leading to the growth of segregation ice in the surface soil and the ground heave which that produces. This occurs about 15 times in the average winter at Rocky Flats, always on a diurnal cycle. Such frost action is preferentially distributed in time and space and cannot be estimated from air temperatures alone. November and March are the months of most frequent frost heave, and then only in the days following precipitation or snowmelt. The most marked frost effects are found on exposed interfluve and hillcrest situations, where there are patches of bare soil. Almost no effects are found on the valley floors. Soil disturbance by segregation ice leads to a marked decrease in soil bulk density, and presumably in soil strength though this change has not been quantitatively defined. However, this does not lead to wind erosion of the soil at the study site because that surface is more influenced by the vegetation cover than by the soil characteristics.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. Characteristics of mannosylerythritol lipids and their environmental potential.

    Science.gov (United States)

    Yu, Mingda; Liu, Zhifeng; Zeng, Guangming; Zhong, Hua; Liu, Yang; Jiang, Yongbing; Li, Min; He, Xiaoxiao; He, Yan

    2015-04-30

    Mannosylerythritol lipids (MELs) are promising biosurfactants containing two glycosyl derivatives and various fatty acids, which are mainly secreted by Pseudozyma as well as Ustilago. In this review, the latest research is demonstrated on production conditions, structural diversity, self-assembling properties and versatile biochemical functions of MELs. The genetic study and synthetic pathways, which mainly influence the type and yield of MELs production. Due to the excellent surface activity, biocompatibility and restorative function, MELs can be used in enviornmental industry, which has not been widely noted. In this paper, the current status of research on enviornmental potential of MELs has been discussed including petroleum degradation, bioconversion of chemical wastes and enhanced bioremediation of amphiphilic wastes. PMID:25723622

  14. Solar energy in California industry - Applications, characteristics and potential

    Science.gov (United States)

    Barbieri, R. H.; Pivirotto, D. S.

    1978-01-01

    Results of a survey to determine the potential applicability of solar thermal energy to industrial processes in California are presented. It is found that if the heat for all industrial processes at temperatures below 212 F were supplied by solar energy, total state energy consumption could be reduced by 100 trillion Btus (2%), while the use of solar energy in processes between 212 and 350 F could displace 500 trillion Btus. The issues and problems with which solar energy must contend are illustrated by a description of fluid milk processing operations. Solar energy application is found to be technically feasible for processes with thermal energy requirements below 212 F, with design, and degree of technical, economic and management feasibility being site specific. It is recommended that the state provide support for federal and industrial research, development and demonstration programs in order to stimulate acceptance of solar process heat application by industry.

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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...

  1. Required characteristics of Paenibacillus polymyxa JB-0501 as potential probiotic.

    Science.gov (United States)

    Naghmouchi, Karim; Baah, John; Cudennec, Benoit; Drider, Djamel

    2013-08-01

    The ability of Paenibacillus polymyxa to inhibit the growth of Escherichia coli generic ATCC 25922 (Escherichia coli ATCC 25922) and to adhere to monolayers of the enterocyte-like human cell line Caco-2 was evaluated. P. polymyxa JB-0501 (P. polymyxa JB-0501), found in a livestock feed probiotic supplement, was compared to P. polymyxa reference strain ATCC 43685 and ATCC 7070 (P. polymyxa ATCC) in terms of carbohydrate utilization and resistance to lysozyme, acid, bile salts, and hydrogen peroxide. JB-0501 grew at pH 4.5 and at H2O2 concentrations less than 7.3 μg/ml and presented a higher affinity to hexadecane and decane. Bile salts at 0.2 % inhibited the growth of all three strains. P. polymyxa JB-0501 and P. polymyxa ATCC 43865 adhered to Caco-2 cell monolayers. The percentage of cells that adhered ranged from about 0.35 to 6.5 % and was partially proportional to the number applied. Contact time (from 15 min to 1 h) had little impact on adhesion. P. polymyxa JB-0501 inhibited the growth of E. coli ATCC 25922, as proven by the diffusion tests in agar. Taken together, these results suggested that P. polymyxa JB-0501 has the potential probiotic properties to justify its consideration as a livestock feed supplement.

  2. 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

  3. 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.

  4. 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.

  5. 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...

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. The nucleon-nucleon correlations and the integral characteristics of the potential distributions in nuclei

    International Nuclear Information System (INIS)

    The integral characteristics of the potential distribution in nuclei, namely the volume integrals, moments and mean square radii are studied in the framework of the semimicroscopic approach to the interaction of low energy nucleons with nuclei on the base of the exchange nucleon-nucleon correlations and the density dependence of effective forces. The ratio of the normalized multipole moments of potential and matter distributions is investigated. The energy dependence of the integral characteristics is analyzed. 15 refs.; 2 tabs

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. THE MODEL CHARACTERISTICS OF JUMP ACTIONS STRUCTURE OF HIGH PERFORMANCE FEMALE VOLLEYBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Stech M.

    2012-12-01

    Full Text Available The purpose of this study was to develop generalized and individual models of the jump actions of skilled female volleyball players. The main prerequisite for the development of the jump actions models were the results of our earlier studies of factor structure of jump actions of 10 sportswomen of the Polish volleyball team "Gedania" (Premier League in the preparatory and competitive periods of the annual cycle of preparation. The athletes age was 22.0 +- 2.9 years, the sports experience - 8.1 +- 3.1 years, body height - 181.9 +- 8.4 years and body weight - 72.8 +- 10.8 kg. Mathematical and statistical processing of the data (the definition of M ± SD and significant differences between the samples was performed using a standard computer program "STATISTICA 7,0". Based on the analysis of the factor structure of 20 jump actions of skilled women volleyball players determined to within 5 of the most informative indexes and their tentative values recommended for the formation of a generalized model of this structure. Comparison of individual models of jump actions of skilled women volleyball players with their generalized models in different periods of preparation can be used for the rational choice of means and methods for the increasing of the training process efficiency.

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

    International Nuclear Information System (INIS)

    Crotoxin, the main component of Crotalus durissus terrificus snake venom, has been studied since 1938. It is a natural polypeptidic complex with pharmacological potential because of its antitumoral properties which has attracted great interest for diagnosis and therapy of oncological diseases. However, Crotoxin mechanism of action and sites of specific interaction on tumor cells are still misunderstood. Breast cancer is the second most frequent type in the world and the most common cancer in women. About 30 to 60% of mammary tumors overexpress epidermal growth factor receptor (EGFR), a transmembrane protein related to cell proliferation. Since literature has reported that Crotoxin antitumoral effect is more potent on cells with EGFR overexpression the objectives of this work were to evaluate Crotoxin cytotoxic effects on mammary tumor cells human breast carcinoma (MCF-7) and Ehrlich tumor cells (murine ascitics carcinoma), and to investigate the specific molecular interaction of Crotoxin on Ehrlich tumor cells. Initially, Crotoxin was radiolabelled with iodine-125 (125I-Crotoxin) and iodine-131 (131I-Crotoxin). Saturation and competition assay were carried out to characterize Crotoxin in vitro interaction; Crotoxin biodistribution studies and singlephoton emission computed tomography (SPECT) of mice bearing Ehrlich tumor have been evaluated to describe in vivo interaction. Our results showed that Crotoxin presented cytotoxic effect against Ehrlich with DL50 in vitro (concentration of compound which is lethal for 50% of cells) of about one micromolar, but did not present significant effect against MCF-7. Morphological alterations characteristic of apoptosis suggests programmed cell death. 125I-Crotoxin interaction with Ehrlich tumor cells was saturable with approximately 70% specificity, and presented Kd=24.98 nmol/L and Bmax=16,570 sites/cell for low affinity binding sites and Kd=0.06 nmol/L and Bmax=210 sites/cell high affinity binding sites; moreover, the

  10. 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

  11. Application of Characteristics of Seismogenic Structures in the Determination of Parameter of Potential Seismic Source Areas

    Institute of Scientific and Technical Information of China (English)

    Zhou Bengang

    2005-01-01

    The characteristics of seismogenic structures are an important basis for delineating the potential seismic source areas and determining the annual occurrence rate of earthquakes. The potential seismic source area does not only have the intension that "this area has the possibility for destructive earthquakes to occur in the future" but also means that earthquakes of high magnitude interval have the characteristics of similar recurrence. When determining the seismic activity parameters of a statistical unit, some active tectonic blocks in the unit may have different background earthquakes. In order to better reflect the heterogeneity in space of seismic activities, it is necessary to divide the potential seismic source areas into three orders.By analyzing the recurrence characteristics of earthquakes of high magnitude interval in the potential source area and calculating the occurrence probability of earthquakes of high magnitude interval in the potential seismic source area in the time window for prediction, the average annual occurrence rate of earthquakes can be obtained by the method of probability equivalent conversion in the time window for prediction. This would be helpful for considering the recurrence characteristics of strong earthquakes in potential source areas within the framework of seismic risk analysis of China. Besides, the insufficient frequency of characteristic earthquakes of the next high magnitude interval in the potential source area and the heterogeneity of strong earthquakes on seismogenic structures are analyzed to see their application in seismic risk analysis.

  12. 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.…

  13. 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

  14. [Aqueous and salt solutions of quinine of low concentrations: self-organization, physicochemical properties and actions on the electrical characteristics of neurons].

    Science.gov (United States)

    Murtazina, L I; Ryzhkina, I S; Mishina, O A; Andrianov, V V; Bogodvid, T Kh; Gaĭnutdinov, Kh L; Muranova, L N; Konovalov, A I

    2014-01-01

    Self-organization, the physicochemical properties of aqueous and salt solutions of quinine and the effects of salt quinine solutions in a wide range of concentrations (1 x 10(-22) - 1 x 10(-3) M) on the electrical characteristics of the edible snail's identified neurons were studied. Similar non-monotonic concentration dependencies of physicochemical properties of aqueous and salt quinine solutions at low concentrations are obtained. This allows of predicting the occurrence of biological effects at low concentrations of quinine solutions. Intrinsic (within 5% of the interval) changes in membrane potential, the amplitude and duration of the neuron action potential under the influence of quinine salt solutions at concentrations of quinine of 1 x 10(-20), 1 x 10(-18), 1 x 10(-10) M are found. For these concentrations the extreme values of specific conductivity and pH are shown.

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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...

  1. 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.

  2. 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...

  3. 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 ...

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. Characteristics of the Research Supervision of Postgraduate Teachers' Action Research

    Science.gov (United States)

    Cornelissen, Frank; van den Berg, Ellen

    2014-01-01

    Today, many institutions of higher education support students in conducting practice-oriented research. This research refers to a broad array of approaches geared toward practitioners' practice. The supervision of such research is of crucial importance, but little is known about its nature and characteristics. This study examined what…

  9. Spatial and Temporal Characteristics of Rice Potential Productivity and Potential Yield Increment in Main Production Regions of China

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiao-jian; TANG Liang; LIU Xiao-jun; CAO Wei-xing; ZHU Yan

    2013-01-01

    The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions. Therefore, analyzing the spatial and temporal characteristics of rice potential productivity and predicting the possible yield increment in main rice production regions of China is important for guiding rice production and ensuring food security. Using meteorological data of main rice production regions from 1961 to 1970 (the 1960s) and from 1996 to 2005 (the 2000s) provided by 333 stations, the potential photosynthetic, photo-thermal and climatic productivities in rice crop of the 1960s and 2000s in main rice production regions of China were predicted, and differences in the spatial and temporal distribution characteristics between two decades were analyzed. Additionally, the potential yield increment based on the high yield target and actual yield of rice in the 2000s were predicted. Compared with the 1960s, the potential photosynthetic productivity of the 2000s was seen to have decreased by 5.40%, with rates in northeastern and southwestern China found to be lower than those in central and southern China. The potential photo-thermal productivity was generally seen to decrease (2.56%) throughout main rice production regions, decreasing most in central and southern China. However, an increase was seen in northeastern and southwestern China. The potential climatic productivity was observed to be lower (7.44%) in the 2000s compared to the 1960s, but increased in parts of central and southern China. The potential yield increment from the actual yield to high yield target in the 2000s were no more than 6×103 kg ha-1 and ranged from 6×103 to 12×103 kg ha-1 in most of the single-and double-cropping rice growing regions, respectively. The yield increasing potential from the high yield target to the potential photo-thermal productivity in 2000s were less than 10×103 kg ha-1 and ranged from 10×103 to 30×103 kg ha-1 in most

  10. 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...

  11. 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.…

  12. 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…

  13. 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

  14. 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

  15. Chiral random matrix model at finite chemical potential: Characteristic determinant and edge universality

    Science.gov (United States)

    Liu, Yizhuang; Nowak, Maciej A.; Zahed, Ismail

    2016-08-01

    We derive an exact formula for the stochastic evolution of the characteristic determinant of a class of deformed Wishart matrices following from a chiral random matrix model of QCD at finite chemical potential. In the WKB approximation, the characteristic determinant describes a sharp droplet of eigenvalues that deforms and expands at large stochastic times. Beyond the WKB limit, the edges of the droplet are fuzzy and described by universal edge functions. At the chiral point, the characteristic determinant in the microscopic limit is universal. Remarkably, the physical chiral condensate at finite chemical potential may be extracted from current and quenched lattice Dirac spectra using the universal edge scaling laws, without having to solve the QCD sign problem.

  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. 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 &...

  18. 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.

  19. 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...

  20. Control of soliton characteristics of the condensate by an arbitrary x-dependent external potential

    Institute of Scientific and Technical Information of China (English)

    Yang Ru-Shu; Yao Chun-Mei; Chen Ri-Xin

    2009-01-01

    This paper presents a family of soliton solutions of the one-dimensional nonlinear Schrodinger equation which describes the dynamics of the dark solitons in Bose-Einstein condensates with an arbitrary x-dependent external potential. The obtained results show that the external potential has an important effect on the dark soliton dynamical characteristics of the condensates. The amplitude,width,and velocity of the output soliton are relative to the source position of the external potential. The smaller the amplitude of the soliton is,the narrower its width is,and the slower the soliton propagates. The collision of two dark solitons is nearly elastic.

  1. 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.

  2. 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.

  3. 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 ...

  4. 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...

  5. 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...

  6. 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...

  7. 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.

  8. 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.

  9. 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).

  10. 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.

  11. Insights from Smart Meters. Identifying Specific Actions, Behaviors and Characteristics that drive savings in Behavior-Based Programs

    Energy Technology Data Exchange (ETDEWEB)

    Todd, Annika [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Perry, Michael [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Smith, Brian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pacific Gas & Electric, San Francisco, CA (United States); Sullivan, Michael [Nexant, San Francisco, CA (United States); Cappers, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Goldman, Charles A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-12-01

    In this report, we use smart meter data to analyze specific actions, behaviors, and characteristics that drive energy savings in a behavior-based (BB) program. Specifically, we examine a Home Energy Report (HER) program. These programs typically obtain 1% to 3% annual savings, and recent studies have shown hourly savings of between 0.5% and 3%. But what is driving these savings? What types of households tend to be “high-savers”, and what behaviors are they adopting? There are several possibilities: one-time behaviors (e.g., changing thermostat settings); reoccurring habitual behaviors (e.g., turning off lights); and equipment purchase behaviors (e.g., energy efficient appliances), and these may vary across households, regions, and over time.

  12. The study on the characteristic of Shuangqiao fault and the ore-control action of it in Daqiaowu deposit

    International Nuclear Information System (INIS)

    Shuangqiao fault is the most important one to control uranium ore bodies in Daqiaowu district of Quzhou area, Zhejiang province, but there is the obvious argument about the attitude which results in the restriction of the U- prognosis in the area. It aims at finding out the movement and ore-control action of the fault by the study on the characteristic of geometry and kinematics. and combining with geophysics in the depth. The Shuangqiao fault's trend is SE instead of NW by researching, and it has the polygenetic movement. There are two obvious stages of tension about the Shuangqiao fault which tally with the two stages of mineralization in Daqiaowu deposit to show the controlled action to ore bodies by it. By the study in-depth, the Shuangqiao fault can lead the metallogenic hydrothermal, and the secondary faults which connect with it can store the ore bodies. The point that the hanging side of fault can control the ore bodies is put forward by making a synthesis of tectonic assembled form and ore-control factors in Daqiaowu deposit. This view is approved by exploration to provide the reference for disposition of uranium prospecting. (authors)

  13. 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

  14. 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.

  15. 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 ...

  16. 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...

  17. Alternative fuel cycle options: performance characteristics and impact on nuclear power growth potential

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Y. I.; Till, C. E.; Rudolph, R. R.; Deen, J. R.; King, M. J.

    1977-09-01

    The fuel utilization characteristics for LWR, SSCR, CANDU and LMFBR reactor concepts are quantified for various fuel cycle options, including once-through cycles, thorium cycles, and denatured cycles. The implications of various alternative reactor deployment strategies on the long-term nuclear power growth potential are then quantified in terms of the maximum nuclear capacity that can be achieved and the growth pattern over time, subject to the constraint of a fixed uranium-resource base. The overall objective of this study is to shed light on any large differences in the long-term potential that exist between various alternative reactor/fuel cycle deployment strategies.

  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. Characteristics of quasi-static potential structures observed in the auroral return current region by Cluster

    OpenAIRE

    G. T. Marklund; Karlsson, T.; Figueiredo, S.; Johansson, T.; Lindqvist, P.-A.; André, M.; S. Buchert; Kistler, L. M.; A. Fazakerley

    2004-01-01

    Temporal and spatial characteristics of intense quasi-static electric fields and associated electric potential structures in the return current region are discussed using Cluster observations at geocentric distances of about 5 Earth radii. Results are presented from four Cluster encounters with such acceleration structures to illustrate common as well as different features of such structures. The electric field structures are characterized by (all values are projected to 100 km altitude) peak...

  20. 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.

  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. 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...

  4. CHARACTERISTICS OF EVOLUTION OF POTENTIAL EVAPORATION IN TIANJIN REGION OF CHINA

    Institute of Scientific and Technical Information of China (English)

    RONG Yan-shu; TU Qi-pu

    2004-01-01

    The characteristics of seasonal and annual changes of potential evaporation, the variations of thermal and dynamical evaporation in different seasons and the relationships between potential evaporation and meteorological elements were analyzed according to the observed data of 9 stations from 1961 to 2001 in the Tianjin region of China. Analyses indicate that thermal evaporation is the main part of the potential evaporation and offers about 90% fraction of to it in summer, while in winter the dynamical evaporation is greater than the thermal one, especially in Jan., offering 100% contribution, that the influence of temperature on the change of potential evaporation was much larger than that of wind, vapor pressure and sunshine duration, and potential evaporation increased by 30.33mm with temperature raise 1℃, and that potential evaporation had a surprising increasing tendency, in particular during the recent decade, with the velocity of 4.22mm/a. The potential evaporation in the Tianjin region will be higher than the past, especially on the global warming background, so that it has the great effects not only on the climatic forcing changes, but also on development of city and economy.

  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. Inverse modeling of soil characteristics from surface soil moisture observations: potential and limitations

    Directory of Open Access Journals (Sweden)

    A. Loew

    2008-01-01

    Full Text Available Land surface models (LSM are widely used as scientific and operational tools to simulate mass and energy fluxes within the soil vegetation atmosphere continuum for numerous applications in meteorology, hydrology or for geobiochemistry studies. A reliable parameterization of these models is important to improve the simulation skills. Soil moisture is a key variable, linking the water and energy fluxes at the land surface. An appropriate parameterisation of soil hydraulic properties is crucial to obtain reliable simulation of soil water content from a LSM scheme. Parameter inversion techniques have been developed for that purpose to infer model parameters from soil moisture measurements at the local scale. On the other hand, remote sensing methods provide a unique opportunity to estimate surface soil moisture content at different spatial scales and with different temporal frequencies and accuracies. The present paper investigates the potential to use surface soil moisture information to infer soil hydraulic characteristics using uncertain observations. Different approaches to retrieve soil characteristics from surface soil moisture observations is evaluated and the impact on the accuracy of the model predictions is quantified. The results indicate that there is in general potential to improve land surface model parameterisations by assimilating surface soil moisture observations. However, a high accuracy in surface soil moisture estimates is required to obtain reliable estimates of soil characteristics.

  12. The characteristics of a potential goal threat predict attention and information-seeking in middle-aged and older adults.

    NARCIS (Netherlands)

    Ouwehand, C.; Ridder, D.T.D. de; Bensing, J.M.

    2008-01-01

    The present experiment examined to what extent features of a potential goal threat and personal characteristics affect attention and information-seeking in 124 adults aged 50–70. We manipulated two characteristics of a potential decline in future health: the amount of control people have over preven

  13. 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

  14. 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.

  15. 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.

  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)

    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.

  17. 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.

  18. 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.

  19. 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.

  20. '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.

  1. Influence of wastewater characteristics on methane potential in food-processing industry wastewaters

    DEFF Research Database (Denmark)

    Maya Altamira, Larisa; Baun, Anders; Angelidaki, Irini;

    2008-01-01

    In this study, we identified the influence of wastewater characteristics on the theoretical and practical methane potential using different food industrial wastewaters as substrates. Ten composite wastewater samples from five industries were investigated. The ultimate practical methane yields (Bo...... of their theoretical yields. The substrate:inoculum ratio as well as the dilution factor of the wastewaters influenced the ultimate practical methane yields differently in each of the wastewaters assessed. Substrate chemical oxygen demand (COD) concentrations did not present any influence on ultimate practical methane...

  2. Biological characteristics of dengue virus and potential targets for drug design

    Institute of Scientific and Technical Information of China (English)

    Rui-feng Qi; Ling Zhang; Cheng-wu Chi

    2008-01-01

    Dengue infection is a major cause of morbidity in tropical and subtropical regions, bringing nearly 40% of the world population at risk and causing more than 20,000 deaths per year. But there is neither a vaccine for dengue disease nor antiviral drugs to treat the infection. In recent years, dengue infection has been particularly prevalent in India, Southeast Asia, Brazil, and Guangdong Province, China. In this article, we present a brief summary of the biological characteristics of dengue virus and associated flaviviruses, and outline the progress on studies of vaccines and drugs based on potential targets of the dengue virus.

  3. Ten minutes of dynamic stretching is sufficient to potentiate vertical jump performance characteristics.

    Science.gov (United States)

    Turki, Olfa; Chaouachi, Anis; Drinkwater, Eric J; Chtara, Moktar; Chamari, Karim; Amri, Mohamed; Behm, David G

    2011-09-01

    The current literature recommends dynamic rather than static stretching for the athletic warm-up. Dynamic stretching and various conditioning stimuli are used to induce potentiation in subsequent athletic performance. However, it is unknown as to which type of activity in conjunction with dynamic stretching within a warm-up provides the optimal potentiation of vertical jump performance. It was the objective of the study to examine the possible potentiating effect of various types of conditioning stimuli with dynamic stretching. Twenty athletes participated in 6 protocols. All the experimental protocols included 10 minutes of dynamic stretching. After the dynamic stretching, the subjects performed a (a) concentric (DS/CON): 3 sets of 3 repetition maximum deadlift exercise; (b) isometric (DS/ISOM): 3 sets of 3-second maximum voluntary contraction back squats; (c) plyometric (DS/PLYO): 3 sets of 3 tuck jumps; (d) eccentric (DS/ECC): 3 modified drop jumps; (e) dynamic stretching only (DS), and (f) control protocol (CON). Before the intervention and at recovery periods of 15 seconds, 4, 8, 12, 16, and 20 minutes, the participants performed 1-2 maximal countermovement jumps. The DS and DS/CON protocols generally had a 95-99% likelihood of exceeding the smallest worthwhile change for vertical jump height, peak power, velocity and force. However, the addition of the deadlift to the DS did not augment the potentiating effect. Time-to-peak potentiation was variable between individuals but was most consistent between 3 and 5 minutes. Thus, the volume and the intensity associated with 10 minutes of dynamic stretching were sufficient to provide the potentiation of vertical jump characteristics. Additional conditioning activities may promote fatigue processes, which do not permit further potentiation. PMID:21792071

  4. 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.

  5. 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.

  6. 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

  7. Antioxidant potential of Phyllanthus fraternus Webster on cyclophosphamide induced changes in sperm characteristics and testicular oxidative damage in mice.

    Science.gov (United States)

    Singh, Sangita; Lata, Swarn; Tiwari, Kavindra Nath

    2015-10-01

    Cyclophasphamide (CPA) is used to treat various types of cancer. It is a cytotoxic alkylating agent widely used in chemotherapeutic regimen. However, the clinical efficacy of CPA is marred by its side effects. In clinical applications of CPA, it becomes necessary to prevent the oxidative stress and reproductive toxicity induced thereby in normal cells. In the present study, we investigated the protective effect of aqueous extract of Phyllanthus fraternus (AEPF) on CPA (200 mg/kg body wt., i.p.) induced changes in sperm characteristics and testicular oxidative damage in male mice. The CPA treated group showed significant decrease in gonadosomatic index (GSI), epididymal sperm count, sperm motility and sperm viability compared to control group, while the CPA + AEPF treated group had significant increase with respect to these variables compared to the CPA-treated group. The elevated levels of lipid peroxidation by CPA were effectively reduced with AEPF. It also exhibited protective action against the CPA induced depletion of antioxidants like catalase and superoxide dismutase. DNA damage was measured by comet assay, biomonitoring with comet assay elicited significant increase in genotoxicity. Genotoxicity caused by CPA was counteracted by aqueous extract of Phyllanthus fraternus. Administration of the plant extract along with CPA restored the histopathological architecture of testis. Thus, the aqueous extract of P. fraternus by virtue of its antioxidant potential can be used as an effective agent to reduce CPA-induced oxidative stress in male mice. PMID:26665295

  8. 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.

  9. 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

  10. Estimating organic micro-pollutant removal potential of activated carbons using UV absorption and carbon characteristics.

    Science.gov (United States)

    Zietzschmann, Frederik; Altmann, Johannes; Ruhl, Aki Sebastian; Dünnbier, Uwe; Dommisch, Ingvild; Sperlich, Alexander; Meinel, Felix; Jekel, Martin

    2014-06-01

    Eight commercially available powdered activated carbons (PAC) were examined regarding organic micro-pollutant (OMP) removal efficiencies in wastewater treatment plant (WWTP) effluent. PAC characteristic numbers such as B.E.T. surface, iodine number and nitrobenzene number were checked for their potential to predict the OMP removal of the PAC products. Furthermore, the PAC-induced removal of UV254 nm absorption (UVA254) in WWTP effluent was determined and also correlated with OMP removal. None of the PAC characteristic numbers can satisfactorily describe OMP removal and accordingly, these characteristics have little informative value on the reduction of OMP concentrations in WWTP effluent. In contrast, UVA254 removal and OMP removal correlate well for carbamazepine, diclofenac, and several iodinated x-ray contrast media. Also, UVA254 removal can roughly describe the average OMP removal of all measured OMP, and can accordingly predict PAC performance in OMP removal. We therefore suggest UVA254 as a handy indicator for the approximation of OMP removal in practical applications where direct OMP concentration quantification is not always available. In continuous operation of large-scale plants, this approach allows for the efficient adjustment of PAC dosing to UVA254, in order to ensure reliable OMP removal whilst minimizing PAC consumption. PMID:24651017

  11. 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.

  12. 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.

  13. Temporal characteristics of online syntactic sentence planning: an event-related potential study.

    Directory of Open Access Journals (Sweden)

    Inge Timmers

    Full Text Available During sentence production, linguistic information (semantics, syntax, phonology of words is retrieved and assembled into a meaningful utterance. There is still debate on how we assemble single words into more complex syntactic structures such as noun phrases or sentences. In the present study, event-related potentials (ERPs were used to investigate the time course of syntactic planning. Thirty-three volunteers described visually animated scenes using naming formats varying in syntactic complexity: from simple words ('W', e.g., "triangle", "red", "square", "green", "to fly towards", to noun phrases ('NP', e.g., "the red triangle", "the green square", "to fly towards", to a sentence ('S', e.g., "The red triangle flies towards the green square.". Behaviourally, we observed an increase in errors and corrections with increasing syntactic complexity, indicating a successful experimental manipulation. In the ERPs following scene onset, syntactic complexity variations were found in a P300-like component ('S'/'NP'>'W' and a fronto-central negativity (linear increase with syntactic complexity. In addition, the scene could display two actions - unpredictable for the participant, as the disambiguation occurred only later in the animation. Time-locked to the moment of visual disambiguation of the action and thus the verb, we observed another P300 component ('S'>'NP'/'W'. The data show for the first time evidence of sensitivity to syntactic planning within the P300 time window, time-locked to visual events critical of syntactic planning. We discuss the findings in the light of current syntactic planning views.

  14. 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.

  15. 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.

  16. DFT-B3LYP computations of electro and thermo molecular characteristics and mode of action of fungicides (chlorophenols).

    Science.gov (United States)

    Dixit, V; Yadav, R A

    2015-08-01

    Density functional theoretical (DFT) calculations of the pesticides; 2-chlorophenol (2-CP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) have been carried out using 6-311++G** basis set available on Gaussian-09 software in order to optimize the molecular structures. The optimized geometry of the molecules has been found to possess Cs symmetry. The charge transfer phenomena occurring in the molecules have been exhibited by (HOMO-LUMO) analysis. The molecular ESP values and mappings of electron density iso-surface with the molecular electrostatic potential (MEP), have been carried out to achieve the information of the size, shape, charge density distribution and site of chemical reactivity of the molecules. Thermo molecular characteristics have been computed to achieve essential environmental influence on the activities of fungicides. PMID:26144387

  17. Physico-chemical characteristics and market potential of sawdust charcoal briquette

    Energy Technology Data Exchange (ETDEWEB)

    Akowuah, Joseph O.; Kemausuor, Francis [Kwame Nkrumah Univ. of Science and Technology, Kumasi (Ghana). Dept. of Agricultural Engineering; Mitchual, Stephen J. [Univ. of Education, Winneba, Kumasi (Ghana). Dept. of Design and Technology Education

    2012-11-01

    In the absence of the widespread distribution of modern cooking fuels in developing countries, efforts are being made to utilise biomass residues which abound in most of these countries. This is intended to replace portions of firewood and charcoal and thereby reduce the cutting down of forests for fuel purposes. Briquettes from agro-residues have therefore been promoted as a better replacement to firewood and charcoals for heating, cooking and other industrial applications in both urban and rural communities. This study sought to assess the physico-chemical properties of charcoal briquettes produced in Ghana and also establish demand for and willingness of potential users to substitute charcoal and firewood with a charcoal briquette. A laboratory experiment was conducted to determine the physicochemical characteristics of the briquettes. This was done prior to the distribution of the briquette to potential users to collaborate their views or otherwise on the handling and burning characteristics of the charcoal briquette. A survey was undertaken a week later using questionnaires to access the willingness of the potential users to use the briquettes. Sixty respondents were purposively selected from households and the hospitality industry for the survey. Results of the physico-chemical assessment of the briquettes were as follows: length (75 to 120 mm), moisture content (5.7% dry basis), density (1.1 g/cm{sup 3}), ash content (2.6%), fixed carbon (20.7%), volatile matter (71%) and calorific value (4,820 kcal/kg). Responses from the survey indicated that the briquette is easy to ignite, has a long burning time and has good heat output. Respondents also observed that the briquettes did not give off sparks and had less smoke and ash content as compared to the regular charcoal they often used. Finally, 93% of the respondents indicated their willingness to use the briquettes if the price was comparable to charcoal. (orig.)

  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. [Pollution Characteristics and Potential Ecological Risk of Heavy Metals in Urban Surface Water Sediments from Yongkang].

    Science.gov (United States)

    Qi, Peng; Yu, Shu-quan; Zhang, Chao; Liang, Li-cheng; Che, Ji-lu

    2015-12-01

    In order to understand the pollution characteristics of heavy metals in surface water sediments of Yongkang, we analyzed the concentrations of 10 heavy metals including Ti, Cr, Mn, Co, Ni, Cu, Zn, As, Pb and Fe in 122 sediment samples, explored the underlying source of heavy metals and then assessed the potential ecological risks of those metals by methods of the index of geo-accumulation and the potential ecological risk. The study results showed that: 10 heavy metal contents followed the order: Fe > Ti > Mn > Zn > Cr > Cu > Ph > Ni > As > Co, all heavy metals except for Ti were 1. 17 to 3.78 times higher than those of Zhejiang Jinhua- Quzhou basin natural soils background values; The concentrations of all heavy metals had a significantly correlation between each other, indicating that those heavy metals had similar sources of pollution, and it mainly came from industrial and vehicle pollutions; The pollution extent of heavy metals in sediments by geo-accumulation index (Igeo) followed the order: Cr > Zn > Ni > Cu > Fe > As > Pb >Mn > Ti, thereinto, Cr, Zn, Cu and Ni were moderately polluted or heavily polluted at some sampling sites; The potential ecological risk of 9 heavy metals in sediments were in the following order: Cu > As > Ni > Cr > Pb > Co > Zn > Mn > Ti, Cu and As contributed the most to the total potential ecological risk, accounting for 22.84% and 21. 62% , others had a total of 55.54% , through the ecological risk assessment, 89. 34% of the potential ecological risk indexes ( RI) were low and 10. 66% were higher. The contamination level of heavy metals in Yongkang was slight in total, but was heavy in local areas.

  1. 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.

  2. Studies on characteristics of nanostructure of N-TiO2 thin films and photo-bactericidal action

    Institute of Scientific and Technical Information of China (English)

    XU Ming-fang; LIN Shan; CHEN Xin-man; PENG Yan-zhi

    2006-01-01

    Pseudomonas aeruginosa strain (AS 1.50) and Bacillus subtilis strain ( AS 1.49 ) from Ming lake were decomposed by photocatalytic nanostructure N-TiO2 thin films in a photo-reactor under UV irradiation. The different thickness nanostructure N-TiO2 thin films coated on mesh grid were prepared by sol-gel method and immobilized at 500 ℃ (films A) or 350 ℃ (films B)for 1 h in a muffle furnace. The results showed that N-TiO2 thin film B (8.18 nm thickness, 2.760 nm height and 25.15 nm diameter) has more uniform granular nanostructure and thinner flat texture than N-TiO2 thin film A (12.17 nm thickness, 3.578 nm height and 27.50 nm diameter). The bactericidal action of N-TiO2 thin film A and film B for Pseudomonas aeruginosa strain (AS1.50) and Bacillus subtilis varniger strain (AS1.439) were investigated in this work. More than 95% of photocatalytic bactericidal efficiency for Pseudomonas aeruginosa strain (AS1.50) and 75% for Bacillus subtilis strain (AS1.439) were achieved by using N-TiO2 thin films-B for 70~80 min of irradiation during the photo-bactericidal experimental process. The results indicated that the photo-induced bactericidal efficiency of N-TiO2 thin films probably depended on the characteristics of the films.

  3. Characteristics of internal-wave and internal-tide deposits and their hydrocarbon potential

    Institute of Scientific and Technical Information of China (English)

    He Youbin; Gao Zhenzhong; Luo Jinxiong; Luo Shunshe; Liu Xuefeng

    2008-01-01

    The study of internal-wave and internal-tide deposits is a new research field on sedimentology during the last ten years. Deep-water traction currents induced by internal waves and internal tides are developed on the modem sea floor, which can form not only all kinds of small scale and dispersal deepwater traction currents deposits, but also large-scale sediment wave in kin-size scale. In this paper,the concepts and features of internal waves and internal tides in oceanography are introduced, and the characteristics, sedimentary sequences, sedimentary microfacies and sedimentation models of internalwave and internal-tide deposits found and the origin of large scale sediment waves in deep sea bottom are summarized. The relationship between internal-wave and internal-tide deposits and petroleum is discussed, and finally internal-wave and internal-tide deposits are shown to be a new potential field for petroleum exploration.

  4. Isolation of lactic acid bacteria with potential protective culture characteristics from fruits

    Science.gov (United States)

    Hashim, Nurul Huda; Sani, Norrakiah Abdullah

    2015-09-01

    Lactic acid bacteria are also known as beneficial microorganisms abundantly found in fermented food products. In this study, lactic acid bacteria were isolated from fresh cut fruits obtained from local markets. Throughout the isolation process from 11 samples of fruits, 225 presumptive lactic acid bacteria were isolated on MRS agar medium. After catalase and oxidase tests, 149 resulted to fit the characteristics of lactic acid bacteria. Further identification using Gram staining was conducted to identify the Gram positive bacteria. After this confirmation, the fermentation characteristics of these isolates were identified. It was found that 87 (58.4%) isolates were heterofermentative, while the rest of 62 (41.6%) are homofermentative lactic acid bacteria. Later, all these isolates were investigated for the ability to inhibit growth of Staphylococcus aureus using agar spot assay method. Seven (4.7%) isolates showed strong antagonistic capacity, while 127 (85.2%) and 8 (5.4%) isolates have medium and weak antagonistic capacity, respectively. The other 7 (4.7%) isolates indicated to have no antagonistic effect on S. aureus. Results support the potential of LAB isolated in this study which showed strong antagonistic activity against S. aureus may be manipulated to become protective cultures in food products. While the homofermentative or heterofermentative LAB can be utilized in fermentation of food and non-food products depending on the by-products required during the fermentation.

  5. Statistical analysis of wind characteristics and wind energy potential in Hong Kong

    International Nuclear Information System (INIS)

    Highlights: • Long-term wind measurements at five typical weather stations in Hong Kong are analyzed. • Wind characteristics and wind energy potential over typical terrain conditions are statistically assessed. • The measured wind speed data fit well with the Weibull distribution function. • Annual, seasonal and monthly variations of the Weibull parameters are presented. • Hilltops and offshore islands are identified as promising sites for wind energy development in Hong Kong. - Abstract: The harvesting of renewable energy sources has become increasingly important to take account of the gradual decline of fossil fuel reserves and the environment degradation associated with the use of fossil fuels. Wind energy, as one of the most well-known renewable energy sources, has been extensively harnessed across the world. Nevertheless, the wind energy exploitation in Hong Kong is still rare. Based on 6-year wind data recorded at five meteorological stations with different terrain conditions, this study presents a statistical analysis of the wind characteristics and wind energy potential at typical sites in Hong Kong by the assistance of Weibull distribution model. The variations of mean wind speed, as well as Weibull parameters, were highlighted on various timescales. Among all the sites, the annual Weibull scale parameter varied from 2.85 m/s to 10.19 m/s, and the range of the annual shape parameter was 1.65–1.99. The highest Weibull scale parameter was observed at a hilltop, whilst the lowest was found at an urban site. The monthly variation of wind power density was presented and discussed for each site. Hilltops and offshore islands demonstrated prominently greater wind power density than urban areas. It was thus indicated that hilltops and offshore islands are the most promising locations for wind energy exploitation in Hong Kong

  6. Inhibition of C. difficile and C. perfringens by commercial and potential probiotic strains and their in-vitro growth characteristics

    OpenAIRE

    Schoster, A; Kokotovic, Branko; Permin, A.; Dedenroth, D.; Guardabassi, L.

    2012-01-01

    Probiotics have gained importance in human and veterinary medicine to prevent and treat clostridial associated enteric disease. Little information is available on commercially produced potential probiotic bacterial strains regarding their inhibition of C. difficile and C. perfringens and their growth characteristics. The objective of this study was to determine the inhibitory effect of commercial and potential probiotic on C. difficile and C. perfringens and assess their growth characteristic...

  7. 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

  8. 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…

  9. 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

  10. 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...

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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)

  18. Chronic fatigue syndrome and impaired peripheral pulse characteristics on orthostasis--a new potential diagnostic biomarker.

    Science.gov (United States)

    Allen, John; Murray, Alan; Di Maria, Costanzo; Newton, Julia L

    2012-02-01

    Autonomic nervous system dysfunction is frequently reported in chronic fatigue syndrome (CFS) with orthostatic intolerance, a common symptom that can be objectively assessed. The frequent finding of autonomic dysfunction and symptoms on standing has the potential to provide a diagnostic biomarker in chronic fatigue. In this study we explored the clinical value of non-invasive optical multi-site photoplethysmography (PPG) technology to assess cardiovascular responses to standing. Multi-site PPG pulses were collected from tissue pads of the ears, fingers and toes of 14 patients with CFS and 14 age-matched sedentary subjects using a measurement protocol of a 10 min baseline (subject supine) followed by 3 min of tilting on a tilt table (head-up to 70°). Percentage change in pulse timing (pulse transit time, PTTf) and pulse amplitude (AMP) at each site were calculated using beat-to-beat pulse wave analysis. A significant reduction in the overall pulse timing response to controlled standing was found for the CFS group (using summed absolute percentage change in PTTf for ear, finger and toe sites, median change of 26% for CFS and 37% for control with p = 0.002). There were no significant differences between subject groups for the AMP measure at any site. Changes in AMP with tilt were, however, weakly significantly and negatively correlated with fatigue severity (p < 0.05). Receiver operating characteristic (ROC) analysis of timing measures produced an area under the curve of 0.81. Experimental linear discriminant classification analysis comparing both timing and amplitude measures produced an overall diagnostic accuracy of 82%. Pulse wave abnormalities have been observed in CFS and represent a potential objective measure to help differentiate between CFS patients and healthy controls. PMID:22273713

  19. Chronic fatigue syndrome and impaired peripheral pulse characteristics on orthostasis–a new potential diagnostic biomarker

    International Nuclear Information System (INIS)

    Autonomic nervous system dysfunction is frequently reported in chronic fatigue syndrome (CFS) with orthostatic intolerance, a common symptom that can be objectively assessed. The frequent finding of autonomic dysfunction and symptoms on standing has the potential to provide a diagnostic biomarker in chronic fatigue. In this study we explored the clinical value of non-invasive optical multi-site photoplethysmography (PPG) technology to assess cardiovascular responses to standing. Multi-site PPG pulses were collected from tissue pads of the ears, fingers and toes of 14 patients with CFS and 14 age-matched sedentary subjects using a measurement protocol of a 10 min baseline (subject supine) followed by 3 min of tilting on a tilt table (head-up to 70°). Percentage change in pulse timing (pulse transit time, PTTf) and pulse amplitude (AMP) at each site were calculated using beat-to-beat pulse wave analysis. A significant reduction in the overall pulse timing response to controlled standing was found for the CFS group (using summed absolute percentage change in PTTf for ear, finger and toe sites, median change of 26% for CFS and 37% for control with p = 0.002). There were no significant differences between subject groups for the AMP measure at any site. Changes in AMP with tilt were, however, weakly significantly and negatively correlated with fatigue severity (p < 0.05). Receiver operating characteristic (ROC) analysis of timing measures produced an area under the curve of 0.81. Experimental linear discriminant classification analysis comparing both timing and amplitude measures produced an overall diagnostic accuracy of 82%. Pulse wave abnormalities have been observed in CFS and represent a potential objective measure to help differentiate between CFS patients and healthy controls. (paper)

  20. Peri-urban dairy production systems in developing countries: Characteristics, potential and opportunities for improvement

    International Nuclear Information System (INIS)

    Full text: Peri-urban dairy production systems in developing countries are discussed with reference to type of systems, their characteristics, potential, and opportunities for improvement. Three types of dairy systems are identified and described: smallholder systems, smallholder co-perative dairy production systems, and intensive dairy production systems. The first two systems are by far the most important, and are associated with increasing intensification. Buffaloes are especially important in South Asia, but elsewhere dairy production mainly involves Holstein-Friesian cross-bred cattle. Dairy goats are important in some countries, but are generally neglected in development programmes. The expansion and intensification of peri-urban dairy production is fuelled by increased demand for milk with associated problems of milk handling and distribution, hygiene and environmental pollution. The major constraints to production are inter alia, choice of species, breeds and availability of animals; feed resources and improved feeding systems; improved breeding, reproduction, and animal health care; management of animal manure, and organised marketing, and market outlets. These constraints provide major opportunities and challenges for research and development to increase dairy production, efficient management of natural resources, and improved livelihoods of poor farmers. Specific areas for research are identified, as also the need of a holistic focus involving interdisciplinary research and integrated natural resource management, in a shared partnership between farmers and scientists that can demonstrate increased productivity and sustainable production systems. Suggestions for performance indicators for such systems are indicated. (author)

  1. Potential Distribution and Transmission Characteristics in a Curved Quadrupole Ion Guide

    Science.gov (United States)

    Zhou, Xiaoyu; Xiong, Caiqiao; Xu, Gaoping; Liu, Hao; Tang, Yin; Zhu, Zhiqiang; Chen, Rui; Qiao, Haoxue; Tseng, Yao-Hsin; Peng, Wen-Ping; Nie, Zongxiu; Chen, Yi

    2011-02-01

    The potential distribution in the curved quadrupole is exactly characterized by the Laplace equation, and an approximate solution to the Laplace equation is calculated. We represent the Laplace equation under the coordinates named minimal rotation frame (MRF) and derive an expression on the hexapole and octopole superposition. Our conclusion is in agreement with the results by the numerical (SIMION) method. Based on the Poincare-Lighthill-Kuo (PLK) method reported in our previous work, the nonlinear effects of ion motion are investigated in detail. The frequency shift of ion motion can be well eliminated by coupling the hexapole component with a positive octopole component, and the transmission efficiency of ions is found to decrease dramatically with the increase of the ionic kinetic energy in the z-direction. Furthermore, the transmission characteristics of ions are discussed with regards to the phase-space theory. The results show that the centrifugally introduced axis shift is mainly responsible for the ion losses. A modified direct current (dc) voltage supply pattern is hence proposed to compensate for this effect.

  2. Effects of grafting on the cadmium accumulation characteristics of the potential Cd-hyperaccumulator Solanum photeinocarpum.

    Science.gov (United States)

    Lin, Lijin; Yang, Daiyu; Wang, Xun; Liao, Ming'an; Wang, Zhihui; Lv, Xiulan; Tang, Fuyi; Liang, Dong; Xia, Hui; Lai, Yunsong; Tang, Yi

    2016-02-01

    The effects of grafting on the cadmium (Cd) accumulation characteristics of the potential Cd-hyperaccumulator Solanum photeinocarpum were studied under Cd stress in our experiment. Four treatments were used in the experiment: ungrafted (UG), self-rooted grafting by the same S. photeinocarpum seedling (SG), self-rooted grafting by two different development stages of S. photeinocarpum seedlings (DG), and grafting on the rootstock of wild potato (PG). SG and DG decreased the root, scion stem, leaf, whole shoot, and whole plant biomasses compared with UG, but increased the rootstock stem biomass, while only PG increased the root and whole plant biomasses. SG and DG increased the Cd contents in the different organs of S. photeinocarpum compared with UG, while PG decreased the Cd content compared with UG. The Cd extraction by the whole plant of S. photeinocarpum was ranked as DG > SG > UG > PG. Additionally, the antioxidant enzyme activities in SG and DG were enhanced compared with UG, while that of PG was reduced compared with UG. The grafting increased the DNA methylation levels and changed the methylation patterns of S. photeinocarpum compared with UG. Therefore, SG and DG can increase the Cd accumulation in S. photeinocarpum, which can be used for the phytoremediation of Cd-contaminated soil. PMID:26739012

  3. Cadmium tolerance and accumulation characteristics of Bidens pilosa L. as a potential Cd-hyperaccumulator

    Energy Technology Data Exchange (ETDEWEB)

    Sun Yuebing [Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Zhou Qixing [Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Key Laboratory of Pollution Processes and Environmental Criteria at Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China)], E-mail: Zhouqx@iae.ac.cn; Wang Lin; Liu Weitao [Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China)

    2009-01-30

    Recently, researchers are becoming interested in using hyperaccumulators for decontamination of heavy metal polluted soils, whereas few species that hyperaccumulate cadmium (Cd) has been identified in the plant kingdom. In this study, the physiological mechanisms at the seedling stage and growth responses and Cd uptake and accumulation at flowering and mature stages of Bidens pilosa L. under Cd treatments were investigated. At the seedling stage, when soil Cd was lower than 16 mg kg{sup -1}, the plant did not show obvious symptom of phytoxicity, and the alterations of chlorophyll (CHL), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), and soluble protein (SP) did not have significant differences when compared with the control. At the flowering and mature stages, under low Cd treatments ({<=}16 mg kg{sup -1}), the application of Cd could facilitate plant growth, resulting in 3.9-11.0% and 5.9-13.8%, respectively, increase in shoots dry biomass compared with the control. The Cd concentrations in stems, leaves and shoots exceeded 100 mg kg{sup -1} when soil Cd was at 8 mg kg{sup -1}, and they were positively correlated with Cd concentration in soils, the bioaccumulation factor (BF) and translocation factor (TF) values were all greater than 1.0. Thus, it is clear that B. pilosa has the basic characteristics of a Cd-hyperaccumulator. All the results elementarily indicated that B. pilosa is a potential Cd-hyperaccumulating plant.

  4. Cadmium tolerance and accumulation characteristics of Bidens pilosa L. as a potential Cd-hyperaccumulator.

    Science.gov (United States)

    Sun, Yuebing; Zhou, Qixing; Wang, Lin; Liu, Weitao

    2009-01-30

    Recently, researchers are becoming interested in using hyperaccumulators for decontamination of heavy metal polluted soils, whereas few species that hyperaccumulate cadmium (Cd) has been identified in the plant kingdom. In this study, the physiological mechanisms at the seedling stage and growth responses and Cd uptake and accumulation at flowering and mature stages of Bidens pilosa L. under Cd treatments were investigated. At the seedling stage, when soil Cd was lower than 16mgkg(-1), the plant did not show obvious symptom of phytoxicity, and the alterations of chlorophyll (CHL), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), and soluble protein (SP) did not have significant differences when compared with the control. At the flowering and mature stages, under low Cd treatments (characteristics of a Cd-hyperaccumulator. All the results elementarily indicated that B. pilosa is a potential Cd-hyperaccumulating plant. PMID:18513866

  5. Characteristics and biogas production potential of municipal solid wastes pretreated with a rotary drum reactor.

    Science.gov (United States)

    Zhu, Baoning; Gikas, Petros; Zhang, Ruihong; Lord, James; Jenkins, Bryan; Li, Xiujin

    2009-02-01

    This study was conducted to determine the characteristics and biogas production potential of organic materials separated from municipal solid wastes using a rotary drum reactor (RDR) process. Four different types of wastes were first pretreated with a commercial RDR system at different retention times (1, 2 and 3 d) and the organic fractions were tested with batch anaerobic digesters with 2.6 g VS L(-1) initial loading. The four types of waste were: municipal solid waste (MSW), a mixture of MSW and paper waste, a mixture of MSW and biosolids, and a mixture of paper and biosolids. After 20 d of thermophilic digestion (50+/-1 degrees C), it was found that the biogas yields of the above materials were in the range of 457-557 mL g VS(-1) and the biogas contained 57.3-60.6% methane. The total solid and volatile solid reductions ranged from 50.2% to 65.0% and 51.8% to 66.8%, respectively. For each material, the change of retention time in the RDR from 1 to 3d did not show significant (alpha=0.05) influence on the biogas yields of the recovered organic materials. Further studies are needed to determine the minimum retention time requirements in the RDR system to achieve effective separation of organic from inorganic materials and produce suitable feedstock for anaerobic digesters. PMID:18849162

  6. Evaluation of soil characteristics potentially affecting arsenic concentration in paddy rice (Oryza sativa L.)

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, Katja, E-mail: katja.bogdan@pflern.uni-hannover.d [Institute of Plant Nutrition, Leibniz Universitaet Hannover, Herrenhaeuser Str. 2, 30419 Hannover (Germany); Schenk, Manfred K., E-mail: schenk@pflern.uni-hannover.d [Institute of Plant Nutrition, Leibniz Universitaet Hannover, Herrenhaeuser Str. 2, 30419 Hannover (Germany)

    2009-10-15

    Paddy rice may contribute considerably to the human intake of As. The knowledge of soil characteristics affecting the As content of the rice plant enables the development of agricultural measures for controlling As uptake. During field surveys in 2004 and 2006, plant samples from 68 fields (Italy, Po-area) revealed markedly differing As concentration in polished rice. The soil factors total As{sub (aquaregia)}, pH, grain size fractions, total C, plant available P{sub (CAL)}, poorly crystalline Fe{sub (oxal.)} and plant available Si{sub (Na-acetate)} content that potentially affect As content of rice were determined. A multiple linear regression analysis showed a significant positive influence of the total As{sub (aquaregia)} and plant available P{sub (CAL)} content and a negative influence of the poorly crystalline Fe{sub (oxal.)} content of the soil on the As content in polished rice and rice straw. Si concentration in rice straw varied widely and was negatively related to As content in straw and polished rice. - Field selection for total As, poorly crystalline Fe and plant available P in soil might contribute to control As content of paddy rice.

  7. Hydrogen production potentials and fermentative characteristics of various substrates with different heat-pretreated natural microflora

    Energy Technology Data Exchange (ETDEWEB)

    Akutsu, Yohei [Department of Civil and Environmental Engineering, Tohoku University, 6-6-06 Aoba, Sendai, Miyagi 980-8579 (Japan); Lee, Dong-Yeol [Research Center for Material Cycles and Waste Management, National Institute for Environmental Studies, 16-2, Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Li, Yu-You [Department of Environmental Science, Tohoku University, 6-6-06 Aoba, Sendai, Miyagi 980-8579 (Japan); Department of Environmental and Municipal Engineering, Tianjin Institute of Urban Construction, Jinjinggonglu 26, Tianjin 300384 (China); Noike, Tatsuya [Advanced Research Institute for the Sciences and Humanities, Nihon University, 2-1 Kudan-kita 4-chome, Chiyoda-ku, Tokyo 102-0073 (Japan)

    2009-07-15

    Batch tests were carried out to investigate the effects of heat-pretreated inocula on the fermentative hydrogen production characteristics of various types of substrates. A total of 8 different inocula and 4 different substrates (starch, glycerol, oil and peptone) were used. Heat pretreatment of the inocula was conducted in order to harvest spore-forming clostridial bacteria. Significant hydrogen production potentials were observed from starch (20.5-174.4 ml H{sub 2}/g-COD{sub starch}) and glycerol (11.5-38.1 ml H{sub 2}/g-COD{sub glycerol}); however, almost no hydrogen was produced from oil and peptone. When starch was used as a substrate, two different fermentation patterns were observed, according to the inocula: butyric acid-type and ethanol-type fermentation. Polymerase chain reaction combined with denaturing gradient gel electrophoresis (PCR-DGGE) analysis was conducted to compare the bacterial structures cultivated on the starch medium. Different species of clostridial bacteria were observed between the butyric acid-type and ethanol-type fermentation cultures. When glycerol was used as a substrate, 1,3-propanediol was the main by-product with each inoculum. The results of the present study suggest that simultaneous production of ethanol or 1,3-propanediol in addition to hydrogen is a more promising strategy than conventional hydrogen production in acidogenesis. (author)

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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...

  19. Action video game training for cognitive enhancement

    OpenAIRE

    Green, C. Shawn; Bavelier, Daphné

    2015-01-01

    Here we review the literature examining the perceptual, attentional, and cognitive benefits of playing one sub-type of video games known as ‘action video games,’ as well as the mechanistic underpinnings of these behavioral effects. We then outline evidence indicating the potential usefulness of these commercial off-the-shelf games for practical, real-world applications such as rehabilitation or the training of job-related skills. Finally, we discuss potential core characteristics of action vi...

  20. Dynamic Variation Characteristics of Phosphorus in Paddy Field Runoff in Saline Land and Its Potential Environmental Effect

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the dynamic variation characteristics of phosphorus in paddy field runoff in saline land and its potential environmental effect. [Method] Taking Qianguo irrigation district in soda-saline land in Songnen Plain as study object, the dynamic variation law of phosphorus in paddy field runoff under different irrigation conditions and its potential environmental effect were discussed. [Result] Surface water in paddy field was alkaline, and scattered soil had poor fertilizer conser...

  1. The potential characteristics analysis of probing signal with the quadratic frequency modulation

    Directory of Open Access Journals (Sweden)

    O. D. Mrachkovsky

    2012-12-01

    Full Text Available Introduction: Complex signals with the button ambiguity function can provide the distance and speed of target independent estimation. The signal with the symmetrical linear frequency modulation has this property in the class of signal with frequency modulation. Problem statement: To show that in the class of signals frequency-shift is signal with button ambiguity function. Such signal is a signal with the quadratic frequency intra-modulation. The potential characteristics research of signal with the quadratic frequency intra-modulation: The signal with quadratic frequency modulation and its properties are considered, analytic form of signal and its spectrum are shown, figures of amplitude spectra of signal are drawn, and figures of ambiguity diagram, cross-correlation functions and response ambiguity function in strong and weak fields are shown. The comparison of the signal with the quadratic frequency intra-modulation and the signal with the symmetrical linear frequency modulation are shown. The result of research is that the ambiguity function form of a signal with the quadratic frequency intra-modulation comes nearer to button in the strong correlation field and it has X – for min the weak correlation field. The autocorrelation function of the signal with the quadratic frequency intra-modulation has some constant level which decreases with signal base increasing. It is revealed that autocorrelation function of the signal has no side lobes. It improves resolution capability of a weak signal against the strong signal. The pedestal level of the autocorrelation function of this signal is a little lower than pedestal level of the autocorrelation function of the signal with the symmetrical linear frequency modulation. Properties of section of cross-correlation function to two peaks and effect of these properties are considered. Signals with the quadratic frequency intra-modulation are expedient for using in the sonar of submarines, because in

  2. 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

  3. 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

  4. 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

  5. Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

    NARCIS (Netherlands)

    Kuijk, A.A. van; Anker, L.C.; Pasman, J.W.; Hendriks, J.C.M.; Elswijk, G.A.F. van; Geurts, A.C.H.

    2009-01-01

    OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps bra

  6. Energy material transport, now through 2000, system characteristics and potential problems. Task 3. Final report - petroleum transportation

    Energy Technology Data Exchange (ETDEWEB)

    DeSteese, J.G.

    1979-03-01

    This report contains a summary characterization of the petroleum transportation system and an assessment of some potential problems that may impact petroleum transportation in the United States during the balance of the century. A primary purpose of this task is to provide information and perspective that contribute to the evaluation of research and development needs and priorities in future programs. The system characterization in Section 3 includes a review of petroleum product movements, modal operations and comparisons, and transportation regulations and safety. This system overview summarizes domestic production and consumption scenarios to the year 2000. A median scenario based on published projections shows that the US will probably rely on foreign oil to supply between 40 and 50 percent of domestic petroleum needs throughout the balance of the century. Potential problems in petroleum transportation were identified by the analysis and prioritization of current issues. The relative priorities of problem concerns were judged on the basis of their overall impact on the system and the immediacy of this potential impact. Two classes of concern are distinguished: 1. Potential problems that appear to require new programmatic action, in addition to effort already committed, to minimize the possible future impact of these concerns. 2. Latent concerns that may increase or decrease in priority or entirely change in nature as they develop. While the trend of these concerns should be monitored, new program action does not appear necessary at this time.

  7. 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.

  8. Sexual Assault Perpetrators’ Justifications for Their Actions: Relationships to Rape Supportive Attitudes, Incident Characteristics, and Future Perpetration

    Science.gov (United States)

    Wegner, Rhiana; Abbey, Antonia; Pierce, Jennifer; Pegram, Sheri E.; Woerner, Jacqueline

    2015-01-01

    Perpetrators use rape supportive attitudes and sexual assault incident characteristics to justify forcing sex on their victims. Perpetrators who can justify their behaviors are at increased risk for future perpetration. This study examined the relationships between rape supportive attitudes, sexual assault incident characteristics, and the post-assault justifications of 183 men sampled from the community who self-reported committing at least one act of sexual aggression. Hierarchical multiple regression analyses indicated that rape supportive attitudes, expectations for having sex, misperceptions of sexual intent, victims’ alcohol consumption, attempts to be alone with her, and the number of consensual sexual activities prior to the unwanted sex were significant predictors of perpetrators’ post-assault use of justifications. Greater use of justifications was a significant predictor of sexual aggression over a 1-year follow-up interval. These findings demonstrate the need for further research exploring when and why perpetrators use post-assault justifications and whether they are amenable to change. PMID:26056162

  9. Action of gamma radiation in the physico-chemical and sensorial characteristics of minimally processed cassava (Manihot esculenta CRANTZ)

    International Nuclear Information System (INIS)

    Nowadays irradiation has been the most studied method of food conservation. The publication of thousand of papers, not just scientific but also technological, economical and social, have proved the technical validity of the irradiation method and showed the ways of how to introduce it in commercial facilities in ali countries of the modem world. Cassava is cultivated almost ali over the world and it is considered one of the most important nutritious sources of calories in human diet. Cassava is a viable food against starving in several poor areas of the world because it is an extremely resistant culture and may reach satisfactory economical yield. Cassava is a quite perishable root, characterized by fast post harvest deterioration. Because of the lack of researches about the effects of radiations in this root, the objective of the present work was to examine the gamma radiation coming from 60Cobalt as a treatment to prolong the shelflife of the root after harvesting, aiming to increase its period of commercialization and to conserve its sensorial characteristics for a longer period. Samples were washed, peeled, cleaned and diced cassava roots packed in polyethylene bags. The treatments were: control; freezing and storage at 18 deg C for 21 days; and irradiation with the doses of 8 and 10 kGy. The control and the irradiated samples were stored under ambient temperature during 21 days. All samples were analyzed at each 7 days for alterations in the physicochemical and sensorial characteristics. The samples were analyzed for pH, acidity, weight, humidity, texture and color. The irradiation did not affect the chemical characteristics of the cassava. Neither the pH nor the acidity, the most relevant variables to verify deterioration in cassava, presented significant alterations during the period of storage. Comparing the irradiated treatments, the dose of 8 kGy was that less affected the physic-chemical characteristics of the cassava and scored the highest notes in the

  10. Characteristics of Crashes with Farm Equipment that Increase Potential for Injury

    Science.gov (United States)

    Peek-Asa, Corinne; Sprince, Nancy L.; Whitten, Paul S.; Falb, Scott R.; Madsen, Murray D.; Zwerling, Craig

    2007-01-01

    Context: Crash fatality and injury rates are higher on rural roadways than other roadway types. Although slow-moving farm vehicles and equipment are risk factors on rural roads, little is known about the characteristics of crashes with farm vehicles/equipment. Purpose: To describe crashes and injuries for the drivers of farm vehicles/equipment and…

  11. Studies on the characteristics of DNA cleavage under the action of 99mTc (O)(PNA-dp)

    International Nuclear Information System (INIS)

    Peptide nucleic acid can be used in the field of tumor gene therapy with minimal non-target damage if it binds to gene with high sequence specificity and selectivity when labeled with radionuclides. In this paper, 99mTc (O) (PNA-dp) was synthesized, and the characteristics of DNA-cleavage were studied. It shows that the radiochemical purity remains over 90% after 6 h storage at room temperature, and the complex can be injected directly. Besides, the obvious DNA cleavage effect can be found after 1 h, and the mechanism of which maybe the cooperation of PNA-dp and the radiation of 99mTc. (authors)

  12. 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...

  13. 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

  14. Derivation of soil-specific streaming potential electrical parameters from hydrodynamic characteristics of partially saturated soils

    CERN Document Server

    Jougnot, Damien; Revil, A; Doussan, Claude; 10.2136/vzj2011.0086

    2012-01-01

    Water movement in unsaturated soils gives rise to measurable electrical potential differences that are related to the flow direction and volumetric fluxes, as well as to the soil properties themselves. Laboratory and field data suggest that these so-called streaming potentials may be several orders of magnitudes larger than theoretical predictions that only consider the influence of the relative permeability and electrical conductivity on the self potential (SP) data. Recent work has partly improved predictions by considering how the volumetric excess charge in the pore space scales with the inverse of water saturation. We present a new theoretical approach that uses the flux-averaged excess charge, not the volumetric excess charge, to predict streaming potentials. We present relationships for how this effective excess charge varies with water saturation for typical soil properties using either the water retention or the relative permeability function. We find large differences between soil types and the pred...

  15. Effect of surface potential of small particles suspended in solution on separation characteristics in a HGMS (High Gradient Magnetic Separator)

    International Nuclear Information System (INIS)

    The effect of surface potential of particles on removal characteristics in the HGMS were studied by using three kinds of small particles with individually different magnetic susceptibility: molybdenum, chrominum and hematite. It was shown that the effect of surface potential of particles such as molybdenum with low magnetic susceptibility value less than 1.7 x 104 appeared at a low linear velocity of liquid less than 150 m/h, and the removal performance increased by controlling the pH range in which the product of ζ-potential of the particle and matrix was negative. The relation between the particles volume captured with matrix and the rest potential of the matrix was determined. (author)

  16. Identifying potential habitat for the endangered Aleutian shield fern using topographical characteristics

    Science.gov (United States)

    Duarte, Adam; Wolcott, Daniel M.; Chow, T. Edwin

    2012-01-01

    The Aleutian shield fern Polystichum aleuticum is endemic to the Aleutian archipelago of Alaska and is listed as endangered pursuant to the U.S. Endangered Species Act. Despite numerous efforts to discover new populations of this species, only four known populations are documented to date, and information is needed to prioritize locations for future surveys. Therefore, we incorporated topographical habitat characteristics (elevation, slope, aspect, distance from coastline, and anthropogenic footprint) found at known Aleutian shield fern locations into a Geographical Information System (GIS) model to create a habitat suitability map for the entirety of the Andreaonof Islands. A total of 18 islands contained 489.26 km2 of highly suitable and moderately suitable habitat when weighting each factor equally. This study reports a habitat suitability map for the endangered Aleutian shield fern using topographical characteristics, which can be used to assist current and future recovery efforts for the species.

  17. Investigation on the mechanical and thermal characteristics of potential buffer materials

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dae Suk; Kim, Kyeong Su [Korea Institute of Geology, Mining and Materials, Taejon (Korea)

    1998-12-01

    The bentonite from the Taekwang Chemical Corporation was tested for its specific gravity, grain-size distribution, Atterberg limits, linear shrinkage, mineralogy, chemistry, compaction characteristics, unconfined compression strength, Young's modulus, poisson's ratio, shear strength, consolidation characteristics, and thermal conductivity. The Jawoldo and was tested for its specific gravity, grain-size distribution, chemistry, and mineralogy. The mixtures of bentonite and sand also were subjected to a laboratory testing program including Atteberg limits, linear shrinkage, unconfined compressive strength, Young's modulus, poisson's ratio, shear strength, and thermal conductivity. All the test procedures and results are described in the paper. (author). 13 refs., 60 figs., 19 tabs.

  18. Beyond the adoption/ non-adoption dichotomy: the impact of innovation characteristics on potential adopters' transition through adoption process stages

    OpenAIRE

    Frambach, R T; Agarwal, M.K.; Nijssen, E.J.

    2002-01-01

    Research on innovation adoption has suffered from a bias towards understanding the factors that affect the dichotomous adoption/non-adoption decision. Much less attention is devoted to the question why potential adopters fail to progress to the adoption stage from earlier stages in the decision making process. Such knowledge is essential to understand what factors actually underlie the non-adoption of an innovation. As perceived innovation characteristics have been found to influence adoption...

  19. The Parent Mealtime Action Scale revised (PMAS-R): Psychometric characteristics and associations with variables of clinical interest.

    Science.gov (United States)

    Hendy, Helen; Harclerode, Whitney; Williams, Keith E

    2016-10-01

    The purpose of the present study was to provide a revised and more psychometrically-examined version of the Parent Mealtime Action Scale (PMAS-R), then to examine how well the PMAS-R subscales explained variance for four variables relevant in clinical settings. Study participants included 238 parents of children referred to a hospital-based feeding program (72.3% male children; mean age = 72.2 months; 80 with autism spectrum disorder, 77 with other special needs, 81 with no special needs). Parents completed questionnaires to report child demographics and diet habits. Parents also used a five-point rating instead of the original three-point rating to report their usage of the 31 PMAS feeding practices. Using five-point ratings, the nine subscales of the PMAS-R demonstrated improved internal reliability and test-retest reliability compared to those published for the original PMAS. ANCOVA indicated that special needs status was the child demographic variable most associated with PMAS-R feeding practices. Hierarchical multiple regression revealed that after controlling for child demographics, the nine PMAS-R subscales explained 26-49% of the variance for four variables of clinical interest (fruit and vegetable consumption, snack consumption, total food variety, and weight status). These variables of clinical interest were most often associated with "permissive" feeding practices including low Daily Fruit and Vegetable (FV) Availability, rarely using Insistence on Eating during meals, often using Many Food Choices, and often using Child-Selected Meals. The present study provides a more psychometrically-sound measure of child feeding practices, documents the association between "permissive feeding" and variables of clinical interest, and identifies specific parent practices included in "permissive feeding". PMID:27221356

  20. 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…

  1. Oxidative potential of particulate matter collected at sites with different source characteristics

    NARCIS (Netherlands)

    Janssen, Nicole A. H.; Yang, Aileen; Strak, Maciej; Steenhof, Maaike; Hellack, Bryan; Gerlofs-Nijland, Miriam E.; Kuhlbusch, Thomas; Kelly, Frank; Harrison, Roy M.; Brunekreef, Bert; Hoek, Gerard; Cassee, Flemming

    2014-01-01

    Background: The oxidative potential (OP) of particulate matter (PM) has been proposed as a more health relevant metric than PM mass. Different assays exist for measuring OP and little is known about how the different assays compare. Aim: To assess the OP of PM collected at different site types and t

  2. 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.

  3. [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.

  4. 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.

  5. Characteristics of spinal microglia in aged and obese mice: potential contributions to impaired sensory behavior

    OpenAIRE

    Lee, Seunghwan; Wu, YaSi; Shi, Xiang Qun; Zhang, Ji

    2015-01-01

    Background Both aging and obesity have been recognized widely as health conditions that profoundly affect individuals, families and the society. Aged and obese people often report altered pain responses while underlying mechanisms have not been fully elucidated. We aim to understand whether spinal microglia could potentially contribute to altered sensory behavior in aged and obese population. Results In this study, we monitored pain behavior in adult (6 months) and aged (17 months) mice fed w...

  6. Activated sewage sludge, a potential animal foodstuff. Part I. Nutritional characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Tacon, A.G.J.

    1979-08-01

    The nutritive value of activated sewage sludge is discussed in terms of its amino acid N, non-amino acid N, carbohydrate, fat, mineral, vitamin and microbial content. Processed activated sewage sludge is described as a stable dark brown material of relatively uniform quality, having a nutritive value broadly equivalent to brewers yeast or a protein-rich cereal. The potential hazards associated with the use of activated sewage sludge as a feed ingredient are discussed. 29 references

  7. Energy Potential Mapping: Visualising Energy Characteristics for the Exergetic Optimisation of the Built Environment

    Directory of Open Access Journals (Sweden)

    Michiel Fremouw

    2013-01-01

    Full Text Available It is difficult to fully satisfy the energy demand of today’s society with renewables. Nevertheless, most of the energy we use is lost as non-functional waste energy, whereas a large part of the built environment’s energy demand is only for low-quality energy, so the initial demand for primary, high-quality energy can be reduced by more effective usage, such as by low-exergy means. Gaining insight into the parameters of energy demands and local renewable and residual energy potentials enables matching energy demand with a fitting potential, not only concerning quantity but taking into account location, temporality and quality as well. The method of Energy Potential Mapping (EPM aims to visualise the energy potentials and demands by making information of quantity, quality and location of demand and supply accessible. The aspect of quality specifically applies to heat and cold. The methodology of EPM will be described and explained with case studies. The focus specifically lies on mapping heat (and cold, one of the main reasons for energy demand in the built environment. The visualisation of exergy, to be simplified as the quality of energy, becomes an extra parameter in the case of Dutch Heat Maps. These maps can help finding opportunities of practical implementations of exchanging or cascading heat or cold. This way EPM and Heat Mapping (HM enables application of exergy principles in the built environment. EPM and HM can be seen as a local energy catalogue and can be useful in spatial planning for energy-based urban and rural plans.

  8. 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.

  9. Effects of Shallow Groundwater Table on Soil Matric Potential and Hydraulic Characteristics

    Institute of Scientific and Technical Information of China (English)

    姜建梅; 赵林; 齐云; 翟喆

    2014-01-01

    Groundwater recharge significantly affects soil moisture redistribution through capillary rise. In this study, the soil matric potential at depths of 5, 10, 20 and 30 cm above the groundwater tables of 10, 30 and 60 cm were measured for 5 d. Soil hydraulic properties were analyzed by using the Philips and de Vries model. Results showed that evaporation mainly influenced the matric potential of the shallow layer at the 5 cm depth regardless of the satura-tion of the layer. Groundwater recharge mainly affected soil moisture at the depth of 20 cm or more. A constant matric potential layer existed between the evaporation front and capillary rise front where moisture content did not change. The isothermal-liquid hydraulic conductivity (KLh) and the thermal-vapor hydraulic conductivity (KvT) were the dominant hydraulic conductivities in the liquid and vapor phases. At the groundwater table depths of 10, 30 and 60 cm, the mean peak values of KLh were 2.32×10-7, 1.63×10-7 and 0.29×10-7 m/s, respectively, whereas the mean peak values of KvT were 2.7×10-7, 2.4×10-7 and 1.8 ×10-7m/s, respectively.

  10. The Ignimbritic tertiary volcanism of the Andes (Peru, Bolivia, Argentina): its characteristics and uraniferous potentiality

    International Nuclear Information System (INIS)

    The petrographic and geochemical characteristics of the volcanism and the primary U distribution at the magmatic stage: alkali-rich volcanic rocks (Peru) appear to be fertile source-rocks, whereas sub alkaline and calc-alkaline rocks (Bolivia and Argentina) are less favorable. Uranium can only be leached from the matrix, due to the stability of the accessory minerals during all the following events. The fertility of a volcanic rock is thus directly controlled by the volume proportion of the matrix and the U fractionation between glass and accessory minerals. The preconcentration and concentration stages: the existence of mineralizations in relation with a fertile rock will depend on other events which must occur successively at the same place: the cooling type and rate of the volcanic pile (pre-concentration stage), the intensity and the duration of the hydrothermal circulations, the presence of reducing agents and trapps. (author)

  11. 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

  12. Characteristics of brainstem auditory evoked potentials of students studying folk dance

    Institute of Scientific and Technical Information of China (English)

    Yunxiang Li; Yuzhen Zhu

    2008-01-01

    BACKGROUND:Previous experiments have demonstrated that brainstem auditory evoked potential is affected by exercise,exercise duration,and frequency. OBJECTIVE:Comparing the brainstem auditory evoked potential of students studying folk dance to students studying other subjects.DESIGN:Observational contrast study. SETTING:Physical Education College,Shandong Normal University PARTICIPANTS:Fifty-five female students were enrolled at Shandong Normal University between September and December in 2005,including 21 students that studied folk dance and 34 students that studied other subjects.The age of the folk dance students averaged(19±1)years and dance training length was(6.0 ±1.5)years.The students that studied other subjects had never taken part in dance training or other physical training,and their age averaged(22±1)years,body height averaged(162±5)cm,body mass averaged(51 ±6)kg.All subjects had no prior ear disease or history of other neurological disorders.All students provided informed consent for the experimental project. METHODS:The neural electricity tester,NDI-200(Shanghai Poseidon Medical Electronic Instrument Factory)was used to examine and record Brainstem Auditory Evoked Potential values of the subjects during silence,as well as to transversally analyze the Brainstem Auditory Evoked Potential values.The electrode positions were cleaned and degreased with soapy water,followed by ethanol.The selected bipolar electrodes were situated on the head:recording electrodes were placed at the Baihui acupoint,and the reference electrode was placed at the mastoid of the measured ear,with grounding electrodes in the center of the forehead.Brainstem Auditory Evoked Potential values were elicited by monaural stimulation of a "click" though an earphone; the other ear was sheltered by the white noise.The click intensity was 102 db,the stimulation frequency was 30 Hz,the bandpass filters were 1 000-3 000 Hz,the sensitivity was 5 μV,and a total of 2 000 sweeps were

  13. Phosphorus release potential and pollution characteristics of sediment in downstream Nansi Lake, China

    Institute of Scientific and Technical Information of China (English)

    Zhijian LI; Qinyan YUE; Baoyu GAO; Yanwen WANG; Qing LIU

    2012-01-01

    The research aimed to evaluate present and potential phosphorous pollution due to high sedimentary phosphorus load and release from sediment, when external phosphorus was reduced in downstream Nansi Lake. Pollution load of the sediment and overlying water was investigated. Kinetics and isotherms of adsorption/release of sedimentary phosphorus were studied to determine equilibrium phosphate concentration (EPCo) and release potential. Kinetics of phosphorus adsorption on sediment and release from sediment were well described by both the pseudo-first-order rate equation and the pseudo-second- order rate equation, but more appropriate to the pseudo- second-order rate equation with the adsorption/release capacity more close to the measured values, suggesting that the processes were chemically rate controlled and dependent on adsorption capacity. Soluble reactive phosphorus (SRP) sorption isotherms on sediment were best fitted by the modified Langmuir model indicating a monolayer adsorption. By comparing EPC0 and SRP of water, the status (adsorption, releasing or in equilibrium) of sediment phosphorus could be determined. The sediments at site S l, S3, S4, S5, and S7 where the EPC0s were greater than the SRPs, had a potential to release phosphorus into the water column. However, those sediments at S9, S10, and S 12, where the EPC0s were approximately equal to the SRPs, were in impermanent equilibrium with overlying water in status of phosphorus, the sediments can be likely to release phosphorus to the water column once the equilibrium was broken. Therefore, sedimentary phos- phorus can be a secondary pollution source in downstream Nansi Lake.

  14. 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.

  15. Polyhydroxyalkanoate (PHA: Review of synthesis, characteristics, processing and potential applications in packaging

    Directory of Open Access Journals (Sweden)

    E. Bugnicourt

    2014-11-01

    Full Text Available Polyhydroxyalkanoates (PHAs are gaining increasing attention in the biodegradable polymer market due to their promising properties such as high biodegradability in different environments, not just in composting plants, and processing versatility. Indeed among biopolymers, these biogenic polyesters represent a potential sustainable replacement for fossil fuel-based thermoplastics. Most commercially available PHAs are obtained with pure microbial cultures grown on renewable feedstocks (i.e. glucose under sterile conditions but recent research studies focus on the use of wastes as growth media. PHA can be extracted from the bacteria cell and then formulated and processed by extrusion for production of rigid and flexible plastic suitable not just for the most assessed medical applications but also considered for applications including packaging, moulded goods, paper coatings, non-woven fabrics, adhesives, films and performance additives. The present paper reviews the different classes of PHAs, their main properties, processing aspects, commercially available ones, as well as limitations and related improvements being researched, with specific focus on potential applications of PHAs in packaging.

  16. Physical characteristics, antimicrobial and odontogenesis potentials of calcium silicate cement containing hinokitiol.

    Science.gov (United States)

    Huang, Ming-Hsien; Shen, Yu-Fang; Hsu, Tuan-Ti; Huang, Tsui-Hsien; Shie, Ming-You

    2016-08-01

    Hinokitiol is a natural material and it has antibacterial and anti-inflammatory effects. The purpose of this study was to evaluate the material characterization, cell viability, antibacterial and anti-inflammatory abilities of the hinokitiol-modified calcium silicate (CS) cement as a root end filling material. The setting times, diametral tensile strength (DTS) values and XRD patterns of CS cements with 0-10mM hinokitiol were examined. Then, the antibacterial effect and the expression levels of cyclooxygenase 2 (COX-2) and interleukin-1 (IL-1) of the hinokitiol-modified CS cements were evaluated. Furthermore, the cytocompatibility, the expression levels of the markers of odontoblastic differentiation, mineralized nodule formation and calcium deposition of human dental pulp cells (hDPCs) cultured on hinokitiol-modified CS cements were determined. The hinokitiol-modified CS cements had better antibacterial and anti-inflammatory abilities and cytocompatibility than non-modified CS cements. Otherwise, the hinokitiol-modified CS cements had suitable setting times and better odontoblastic potential of hDPCs. Previous report pointed out that the root-end filling materials may induce inflammatory cytokines reaction. In our study, hinokitiol-modified CS cements not only inhibited the expression level of inflammatory cytokines, but also had better cytocompatibility, antimicrobial properties and active ability of odontoblastic differentiation of hDPCs. Therefore, the hinokitiol-modified CS cement may be a potential root end filling material for clinic. PMID:27157721

  17. ASR potential of quartz based on expansion values and microscopic characteristics of mortar bars

    Science.gov (United States)

    Stastna, Aneta; Sachlova, Sarka; Kuchynova, Marketa; Pertold, Zdenek; Prikryl, Richard

    2016-04-01

    The alkali-silica reaction (ASR) is one of the most damaging factors for concrete structures. Different analytical techniques are used to quantify ASR potential of aggregates. The accelerated mortar bar test (ASTM C1260) in combination with the petrographic examination of aggregates by microscopic techniques belongs to the frequently employed methods. Such a methodical approach enables quantification of the ASR potential, based on the expansion values of accelerated mortar bars; and also to identify deleterious components in aggregates. In this study, the accelerated mortar bar test (ASTM C1260) was modified and combined with the scanning electron microscopy of polished sections prepared from mortar bars. The standard 14-day test period of mortar bars was prolonged to 1-year. ASR potential of aggregates was assessed based on expansion values (both 14-day and 1-year) of mortar bars and microscopic analysis of ASR products (alkali silica gels, microcracks, dissolution gaps) detected in the sections. Different varieties of quartz-rich rocks including chert, quartz meta-greywacke, three types of quartzite and pegmatite were used as aggregate. Only quartz from pegmatite was assessed to be non reactive (14-day expansion of 0.08%, 1-year expansion of 1.25%). Aggregate sections exhibited minor ASR products even after 1-year of mortar bar immersion in 1 M NaOH. Expansion values of the rest of samples exceeded the limit of 0.10% after 14-day test period indicating aggregates as reactive. The highest ASR potential was detected in mortar bars containing chert (14-day expansion of 0.55%, 1-year expansion of 2.70%) and quartz meta-greywacke (14-day expansion of 0.46%, 1-year expansion of 2.41%). The high ASR potential was explained by presence of cryptocrystalline matrix in significant volumes (24 - 65 vol%). Influence of the lengths of the immersion in the alkaline solution was observed mainly in the microstructure of the cement paste and on the extension of ASR products. The

  18. Erythorbyl laurate as a potential food additive with multi-functionalities: Interfacial characteristics and antioxidant activity.

    Science.gov (United States)

    Park, Kyung-Min; Lee, Min Joo; Jo, Su-Kyung; Choi, Seung Jun; Lee, JaeHwan; Chang, Pahn-Shick

    2017-01-15

    The interfacial characteristics and antioxidant activities of erythorbyl laurate were investigated to provide information on practical applications as a multi-functional food additive. The critical micelle concentration (CMC) of erythorbyl laurate was 0.101mM and its foam stability was three times (half-life 24.33±0.94h) higher than that of Tween 20 (8.00±1.63h). In free radical scavenging assay, the negligible decrease in EC50 of erythorbyl laurate compared to erythorbic acid manifested that C-5 selective esterification of erythorbic acid with an acyl group (lauric acid) did not reduce the inherent antioxidant activity of the donor (erythorbic acid). Erythorbyl laurate formed lipid peroxides slower (i.e. retarded oxidation) in an emulsion system than did erythorbic acid. The localization of erythorbyl laurate as an emulsifier allowed the antioxidant molecules to be concentrated at the oil-water interface where oxidation is prevalent, which led to more effective retardation of lipid oxidation. PMID:27542455

  19. THE RELATIVE INFLUENCE OF AGE CHARACTERISTICS IN THE PROCESS OF IMPLEMENTING SPORTING POTENTIAL OF YOUNG PLAYERS

    Directory of Open Access Journals (Sweden)

    A. D. Dugbley

    2014-04-01

    Full Text Available Formation of the various life-support systems of teenage body is so heterochronous that among peers by chronological age, there are often significant cognitive, physical and emotional differences, accompanied by a fairly significant differences in weight and growth rates, between children who was born in the early and late stage of the year. This fact can have a significant impact on the academic and athletic activities of children. It's necessary to define the relative influence of age characteristics for the selection procedure of young footballers.The experiment was participated by 82 pupils of government school №63 and 172 young footballers of various teams in Moscow.According to the results of the experiment was certain that during the long-term collaboration in football, the shift of attention in favor of children who was born earlier than others within one year, leads to the devaluation of the selection and rejection of the professional activities by a large percentage of talented footballers that have a negative impact on the level of youth football in the country.Purchase on Elibrary.ru > Buy now

  20. CARPOOLING AS AN ALTERNATIVE TO IMPROVING TRANSIT ACCEPTABILITY AND CHARACTERISTICS OF POTENTIAL USERS

    Directory of Open Access Journals (Sweden)

    Keila Rodrigues De Moura

    2014-12-01

    Full Text Available The world is undergoing major changes due to technological innovations, which make life easier for people, however, has caused great impacts in relation to urban mobility and the environment. Traffic is one of the main problems of the modern era, however, difficult people leave the comfort of the car by collective alternatives. The carpooling or car sharing is an alternative for sustainable traffic improvement, since it can help to reduce the number of vehicles circulating on the public highway and hence to the environment. The aim of this study is to evaluate the acceptance of carpooling among students of a college in the city of Botucatu, and to identify characteristics associated with interest in participating in a program of carpooling. For this, an observational study using a sample survey was conducted among the students of a public institution of higher learning, using a structured questionnaire to collect data, and the sample of students obtained through a random process. After collecting the data, they were analyzed using descriptive statistics and the Goodman test to study the association between variables. It was found that only 5.5% of respondents did not have an interest in giving a ride to a colleague or employee of the institution and that gender, age, period studying and ownership of a vehicle are not associated with interest in participating in a carpooling program.

  1. The characteristics of event related potential in the cognitive course of individual Chinese characters.

    Science.gov (United States)

    Mingshi, Wang; Hongqiang, Yu; Huisheng, Lu

    2005-01-01

    The difference between the Chinese and English character recognition process and the characteristics of Chinese character recognition process are investigated by analyzing the ERP difference between the matched and mismatched ending strokes of a single Chinese character. First, the P300 are observed in the mismatched ERP waveforms, which don't exist in the matched ERP waveforms (Ppictograph Chinese characters are not only affected by the semanteme, but also closely related to its image of the figure. Secondly, the amplitude of the N400 in the mismatched ending strokes of Chinese character is obviously higher than that in the matched groups (P<0.05). The N400 is distributed in the other areas except the right side of temporal lobe and is higher in the left side. However, the amplitude of N400 in the waveforms has no obvious distinction between the cerebral hemispheres, where the amplitude of N400 are obtained by distracting the ERP of the mismatched individual Chinese character by the ERP of the matched group. These results show that the difference between cerebral hemispheres is attributed to the formal and phonic processing, not due to the semantic processing, which verify that the left and right cerebral hemisphere are both used in the Chinese character recognition, which is very different from the English character recognition, where the left side cerebral hemisphere is used with high percentage.

  2. 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...

  3. Characteristic features of inhibitory junction potentials evoked by single stimuli in the guinea-pig isolated taenia caeci.

    Science.gov (United States)

    Bridgewater, M; Cunnane, T C; Brading, A F

    1995-05-15

    1. Changes in membrane potential of the guinea-pig isolated taenia caeci evoked by single stimuli have been investigated using intracellular recording techniques. Nifedipine (10 microM) was used to arrest spontaneous muscle action potentials. Single stimuli elicited complex junction potentials which consisted of both excitatory and inhibitory components. 2. The excitatory component of the compound junction potential was unaffected by hexamethonium (100 microM) but abolished by atropine (1 microM) and omega-conotoxin GVIA (10-100 nM). 3. In the presence of atropine, single stimuli elicited fast inhibitory junction potentials (IJPs). IJPs were sometimes biphasic during repolarization with a noticeable 'slow tail'. Apamin (30-100 nM) potently inhibited the fast IJP and revealed an underlying slow IJP. 4. The fast IJP was also abolished by omega-conotoxin GVIA (100 nM). However, the slow IJP was insensitive to omega-conotoxin GVIA but was abolished by cadmium (30 microM). 5. Guanethidine (3 microM) and N omega-nitro-L-arginine (10-100 microM) had no detectable effects on either of the IJPs. The dye Reactive Blue 2 reduced the amplitude of the fast IJP but this reduction was associated with a membrane hyperpolarization. 6. The existence of two distinct IJPs in the guinea-pig taenia caeci has been demonstrated. The ability of omega-conotoxin GVIA to selectively abolish the fast IJP leaving the slow IJP intact suggests that separate nerves are involved in mediating these responses.

  4. Experimental study on the indoor temperature variation characteristics and energy conservation potentialities in winter

    Institute of Scientific and Technical Information of China (English)

    LONGEnshen; WANGYong; FUXiangzhao

    2003-01-01

    This paper conducts an experiment on the starting and stopping of an indoor air-conditioner in winter, and obtains a sedes of experimental data of the indoor environmental temperature. With these data, it makes a further calculation of the indoor PMV index during the start-up and shutdown of the air-conditioner. On condition that the human body''s thermal comfort is basically guaranteed, an optimal combination mode of time is worked out to start and stop the air conditioner that operates intermittently in the experimental room. If the starting and stopping of the air-conditioner is managed in this way, the maximum energy-saving potentiality can be 41% compared with the traditional continuous operation.

  5. Characteristics of thermal hydraulic stability in a HYPER system with enhanced natural circulation potential

    Energy Technology Data Exchange (ETDEWEB)

    Tak, Nam Il; Park, Won S.; Han, Seok Jung

    1999-06-01

    Pb-Bi eutectic chosen as a coolant of HYPER is an excellent heat transfer medium but requires relatively large pumping power. Thus the mixed cooling concept to increase economy and safety is being considered for HYPER. In this cooling concept, a large fraction of total thermal power is carried by natural circulation. However, the mixed cooling concept has been considered for conceptual designs only an it has never been applied to real reactors. The purpose of the present study is to provide simple tools to analyze mixed flow and to examine fundamental stability characteristics of mixed flow. Conventional one-dimensional approaches using mass, momentum, and energy conservation are used to describe a forced circulating flow affected by a large buoyancy force. The results of simple analysis using preliminary design parameters of HYPER show that cooling by mixed flow is possible only when the total pressure loss of system is sufficiently low. The stability behavior of mixed flow in a simple rectangular loop has been studied using numerical solutions of the governing equations. As in the case of natural circulation, three types of flow regions, such as stable, neutrally stable, and unstable regions, were found. The stability map of mixed flow has been obtained using the results of calculations. Forced flow due to the pump is found to increase the stability of the loop, since the stable portion of the stability map is increased. However, the unstable region of the mixed flow does not completely disappear, even though the pump exists. (author). 37 refs., 4 tabs., 23 figs.

  6. Pyrolysis Characteristics and Kinetics of Phoenix Tree Residues as a Potential Energy

    Directory of Open Access Journals (Sweden)

    H. Li

    2015-09-01

    Full Text Available By using a thermogravimetric analyser under argon atmosphere, the pyrolysis process and the kinetic model of phoenix tree residues (the little stem, middle stem, and leaf at a 30 °C min−1 heating rate and the phoenix tree mix at three different heating rates (10 °C min−1, 30 °C min−1, and 50 °C min−1 were examined. The catalyst and the co-pyrolysis samples were at a 30 °C min−1 heating rate. The catalysts were Na2CO3, ZnCl2 and CaO in a mass fraction of 5 %. The experimental results revealed that the phoenix tree residues pyrolysis process consisted of three stages: dehydration stage, main pyrolysis stage, and the slow decomposition of residues. As the heating rate increased, the pyrolysis characteristic temperature of the phoenix tree grew, there was a backward-shift of the pyrolysis rate curve, and the mass loss rate gradually increased. The phoenix tree residues’ activation energy changed throughout the whole pyrolysis process, and the pyrolysis temperature ranges of the three main components (cellulose, hemicellulose, and lignin existed in overlapping phenomenon. As compared to the little stem, middle stem, and leaf, the phoenix tree mix was more likely to be pyrolysed under the same heating rate. Different catalysts had a different impact on the pyrolysis: ZnCl2 moved the start point of the reaction to the lower temperatures, but did not speed up the reaction; Na2CO3 speeded up the reaction without changing the start point of the reaction; CaO speeded up the reaction, moved the start point of the reaction to higher temperatures.

  7. 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...

  8. 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

  9. 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...

  10. In-vitro growth characteristics of commercial probiotic strains and their potential for inhibition of Clostridium difficile and Clostridium perfringens

    DEFF Research Database (Denmark)

    Schoster, A.; Kokotovic, Branko; Permin, A.;

    2012-01-01

    under aerobic conditions was assessed. To evaluate inhibition of C. difficile and C. perfringens sterile supernatant of the probiotic culture was added to BHI inoculated with a standard C. difficile or C. perfringens suspension. Growth was measured spectrophotometrically at 0 and 24h and compared to the......-four percent grew under aerobic conditions. Ninety-four percent of strains were inhibitory (0-20% growth compared to control) against C. difficile and 76% were inhibitory against C. perfringens. Sixty percent of the tested strains showed favourable in-vitro characteristics for use as potential equine...

  11. Human Origin Lactobacillus casei Isolated from Indonesian Infants Demonstrating Potential Characteristics as Probiotics in vitro

    Directory of Open Access Journals (Sweden)

    Widodo .

    2015-11-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The aim of this experiment was to isolate and identify Lactic Acid Bacteria (LAB from infant faeces and subsequent evaluation of its potential probiotics. LAB was isolated from faeces of infants who consumed breast milk as the only source of diet on L-cysteine-supplemented MRS Agar, and incubated on 37oC for 48 hours. Colonies grew on this media were then identifi ed based on morphological, physiological and molecular approaches. Morphological and physiological identifi cations based on Gram staining, shape, motility, spore formation, catalase, CO2 and NH3 production, and the ability to grow on temperature at 10oC and 45oC. Molecular identifi cation based on the amplifi cation of 16S rRNA gene. The potential application of selected isolates for probiotics was evaluated based on the ability to grow on media with low pH and the addition of 0.5% bile salts, the ability to inhibit the growth of pathogenic Bacillus cereus and Eschericia coli, and in vitroadherence ability. On the basis of morphological, physiological and molecular analysis of 16S rRNA gene, it was concluded that the selected isolate 1AF was a strain of Lactobacillus casei. Evaluation of probiotic in vitro showed that 60.4% of cells were resistant

  12. Potential performance characteristics of ICESat-2/ATLAS for canopy height retrievals in different ecosystems

    Science.gov (United States)

    Neuenschwander, A. L.; Pitts, K.

    2015-12-01

    With an expected launch in late 2017 (or early 2018), the ICESat-2 satellite will provide a global distribution of geodetic measurements of both the terrain surface and relative canopy heights which will provide a significant benefit to society through a variety of applications including forest structural mapping and improved global digital terrain models. The Advanced Topographic Laser Altimeter System (ATLAS) instrument on ICESat-2 will utilize a photon counting lidar which utilizes low power laser pulse with detectors sensitive at the single photon level. Due to this type of detector, any returned photon whether from the reflected signal or solar background can trigger a detection event. The ATLAS instrument will record the arrival time associated with a single photon detection that can occur anywhere within the vertical distribution of the reflected signal, that is, anywhere within the vertical distribution of the canopy. One of the uncertainties facing the ecosystem community is a comprehensive understanding of the performance of ICESat-2 will be for various ecosystems. Specifically, which ecosystems -and to a greater extent- what amount of canopy cover will create constraints on the ability to derive relative canopy height from ICESat-2 measurements. This paper aims to provide the science and user community of the ICESat-2 land/vegetation data products with a realistic understanding of the performance characteristics and subsequent data quality and the associated errors. To simulate ICESat-2/ATLAS data, data from small-footprint waveform lidar are the best surrogate for empirically deriving simulated ICESat-2 data as the entire temporal profile of the laser energy is recorded on each waveform. As such, a normalized waveform is the probability of where a photon is returned from the reflecting surface along the laser line-of-sight. Using this empirical approach, simulated ICESat-2 data can be developed for a variety of ecosystems ranging from sparse shrublands

  13. Characteristics of THMFP increase in secondary effluent and its potential toxicity.

    Science.gov (United States)

    Wu, Maoni N; Wang, Xiaochang C; Ma, Xiaoyan Y

    2013-10-15

    Chlorination of the secondary effluent from domestic wastewater treatment plants (WWTP) is suspicious of toxic effects due to the formation of trihalomethanes (THMs). In order to clarify this mechanism, samples were collected from the inlet and outlet of a WWTP, and a series of analyses were conducted on the relationship between THMs formation and the toxicity of the secondary effluent after chlorination. By three-dimensional fluorescence spectrometry it was clarified that the biological wastewater treatment process was accompanied with the formation of humic- and fulvic-like substances which were typical THMs precursors as shown by their high thihalomethane formation potential (THMFP) as well as high specific ultraviolet absorbance (SUVA). As a result of bioassay using a freshwater luminescent bacterium Vibrio-qinghaiensis sp.-Q67, a linear relationship was obtained between the concentration of THMs after chlorinating the effluent and its toxicity expressed as the inhibition of the luminescent light. The effective THMs concentration corresponding to a 50% inhibition was 318 μg/L at a chlorine dose of 19.6 mg/L as Cl2. THMs formation may be the direct reason for the increase of toxicity in the secondary effluent when chlorine was used as disinfectant. PMID:23959252

  14. Characteristics of the summit lakes of Ambae volcano and their potential for generating lahars

    Directory of Open Access Journals (Sweden)

    P. Bani

    2009-08-01

    Full Text Available Volcanic eruptions through crater lakes often generate lahars, causing loss of life and property. On Ambae volcano, recent eruptive activities have rather tended to reduce the water volume in the crater lake (Lake Voui, in turn, reducing the chances for outburst floods. Lake Voui occupies a central position in the summit caldera and is well enclosed by the caldera relief. Eruptions with significantly higher magnitude than that of 1995 and 2005 are required for an outburst. A more probable scenario for lahar events is the overflow from Lake Manaro Lakua bounded on the eastern side by the caldera wall. Morphology and bathymetry analysis have been used to identify the weakest point of the caldera rim from which water from Lake Manaro Lakua may overflow to initiate lahars. The 1916 disaster described on south-east Ambae was possibly triggered by such an outburst from Lake Manaro Lakua. Taking into account the current level of Lake Manaro Lakua well below a critical overflow point, and the apparently low potential of Lake Voui eruptions to trigger lahars, the Ambae summit lakes may not be directly responsible for numerous lahar deposits identified around the Island.

  15. Accumulation and tolerance characteristics of cadmium in a potential hyperaccumulator--Lonicera japonica Thunb.

    Science.gov (United States)

    Liu, Zhouli; He, Xingyuan; Chen, Wei; Yuan, Fenghui; Yan, Kun; Tao, Dali

    2009-09-30

    Phytoremediation using hyperaccumulators is a promising technique of removing soil pollutants. In the study, growth responses, cadmium (Cd) accumulation capability and physiological mechanisms of Lonicera japonica Thunb. under Cd stress were investigated. Exposed to 5 and 10 mg L(-1) Cd, the plants did not show any visual symptoms, furthermore, the height, dry biomass of leaves, roots and total and the chlorophyll (CHL) content were obtained different grade increase. When the concentration of Cd was up to 50 mg L(-1), the height, dry biomass of leaves and roots had not significant differences compared with the control. The indexes of tolerance (IT) were all above 0.8. The maintenance of high superoxide dismutase (SOD) and catalase (CAT) activities was observed along with the increased Cd concentration, suggesting strong internal detoxification mechanisms inside plant cells. After 21 days exposure to 25 mg L(-1) Cd, stem and shoot Cd concentrations reached 344.49+/-0.71 and 286.12+/-9.38 microg g(-1) DW, respectively and the plant had higher bioaccumulation coefficient (BC) and translocation factor (TF). According to these results, it was shown L. japonica had strong tolerance and accumulation capability to Cd, therefore it is a potential Cd-hyperaccumulator. PMID:19380199

  16. Accumulation and tolerance characteristics of cadmium in a potential hyperaccumulator-Lonicera japonica Thunb

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhouli [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang 110016 (China); Graduate School, Chinese Academy of Sciences, Jia 19 Yuquan Road, Beijing 100039 (China); He Xingyuan, E-mail: hexy@iae.ac.cn [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang 110016 (China); Chen Wei; Yuan Fenghui [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang 110016 (China); Yan Kun [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang 110016 (China); Graduate School, Chinese Academy of Sciences, Jia 19 Yuquan Road, Beijing 100039 (China); Tao Dali [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang 110016 (China)

    2009-09-30

    Phytoremediation using hyperaccumulators is a promising technique of removing soil pollutants. In the study, growth responses, cadmium (Cd) accumulation capability and physiological mechanisms of Lonicera japonica Thunb. under Cd stress were investigated. Exposed to 5 and 10 mg L{sup -1} Cd, the plants did not show any visual symptoms, furthermore, the height, dry biomass of leaves, roots and total and the chlorophyll (CHL) content were obtained different grade increase. When the concentration of Cd was up to 50 mg L{sup -1}, the height, dry biomass of leaves and roots had not significant differences compared with the control. The indexes of tolerance (IT) were all above 0.8. The maintenance of high superoxide dismutase (SOD) and catalase (CAT) activities was observed along with the increased Cd concentration, suggesting strong internal detoxification mechanisms inside plant cells. After 21 days exposure to 25 mg L{sup -1} Cd, stem and shoot Cd concentrations reached 344.49 {+-} 0.71 and 286.12 {+-} 9.38 {mu}g g{sup -1} DW, respectively and the plant had higher bioaccumulation coefficient (BC) and translocation factor (TF). According to these results, it was shown L. japonica had strong tolerance and accumulation capability to Cd, therefore it is a potential Cd-hyperaccumulator.

  17. Exploitation of the nutritional and functional characteristics of traditional Italian legumes: the potential of sourdough fermentation.

    Science.gov (United States)

    Curiel, José Antonio; Coda, Rossana; Centomani, Isabella; Summo, Carmine; Gobbetti, Marco; Rizzello, Carlo Giuseppe

    2015-03-01

    This study aimed at evaluating the composition of nineteen traditional Italian legumes and at investigating the potential of the sourdough fermentation with selected lactic acid bacteria to improve the nutritional and functional features. Traditional Italian legumes, all with product certifications and belonging to Phaseolus vulgaris, Cicer arietinum, Lathyrus sativus, Lens culinaris and Pisum sativum species, were used in this study. Seeds were milled, and flours were analyzed for proximate composition and subjected to sourdough fermentation at 30°C for 24h. Lactobacillus plantarum C48 and Lactobacillus brevis AM7 were used as selected starters. Compared to control doughs, without bacterial inoculum, the concentrations of free amino acids (FAA), soluble fibres, and total phenols increased for all legume sourdoughs. Raffinose decreased of up to ca. 64%. During sourdough fermentation, the level of GABA markedly increased and reached values up to 624mg/kg. Condensed tannins decreased. At the same time, almost all legume sourdoughs showed increases of the antioxidant and phytase activities. As shown by PCA analysis based on data of total FAA, GABA, raffinose, soluble/insoluble dietary fibre, condensed tannins and antioxidant and phytase activities, all legume sourdoughs were clearly differentiated from control doughs. The traditional Italian legumes are bio-diverse, and all showed high levels of nutritional elements and suitability for optimal sourdough fermentation. Legume flours subjected to sourdough fermentation would be suitable to be used alone or better in mixture with cereals, and as gluten-free ingredients for making novel and healthy foods. PMID:25522057

  18. Effects of piezoelectric potential on the transport characteristics of metal-ZnO nanowire-metal field effect transistor

    KAUST Repository

    Gao, Zhiyuan

    2009-01-01

    We have investigated the effects of piezoelectric potential in a ZnO nanowire on the transport characteristics of the nanowire based field effect transistor through numerical calculations and experimental observations. Under different straining conditions including stretching, compressing, twisting, and their combination, a piezoelectric potential is created throughout the nanowire to modulatealternate the transport property of the metal-ZnO nanowire contacts, resulting in a switch between symmetric and asymmetric contacts at the two ends, or even turning an Ohmic contact type into a diode. The commonly observed natural rectifying behavior of the as-fabricated ZnO nanowire can be attributed to the strain that was unpurposely created in the nanowire during device fabrication and material handling. This work provides further evidence on piezopotential governed electronic transport and devices, e.g., piezotronics.

  19. Comparative characteristics of the mineralogical composition of Ti-Zr potential placer district

    Science.gov (United States)

    Ovchinnikova, Mary

    2016-04-01

    Russia has a great off-balance reserves of TiO2 and it is ranked fourth in the world after Ukraine, China and Australia. Inferred resources are also very significant. But today Russia produces titanium products only from imported raw materials. Exploration of Ti-raw material is carried out in Russia only as passing on comprehensive deposits. As a result of work conducted in 1959, Stavropolsky elevation was discovered Stavropolsky Ti-Zr alluvial basin. The same mineralogical composition has Ti-Zr Ergeninsky potential alluvial district, which is located north-eastern of Stavropolsky littoral basin. Administratively, Ergeninsky area, basically, covers territory of Kalmikia, and partially Rostovsky and Volgogradsky area. In terms of tectonics, it occupies an area of the junction of the East European platform and Karpinsky Ridge. Alluvial basin holds really magnificent range. There are two hypotheses as to where was the demolition of ore sand. According to the first demolition of the original ore material was from crumbling crystalline rocks southern East European platform. The second hypothesis links the formation of these placers due to the erosion of crystalline basement rocks of the Greater Caucasus, which is explained by the fact of the existence of the Sarmatian paleo sea. There are two productive horizons on the territory of Ergeninsky potential placer district. First - the lower productive horizon it has a capacity of 1.5 to 6.3 m and the total content of titanium and zirconium minerals 12 to 66 kg m³. Second - upper productive horizon. 1.5 to 4.3 m and the total content of titanium and zirconium minerals from 21 to 50 kg m³. Earlier in the study of the area, only samples from the upper productive horizon were considered. At the beginning petrophysical analysis of all available samples, was conducted. Before you choose a basic test, each of the 26 studied several petrophysical properties: 1. Magnetic susceptibility (κ, 10-5 units. C) 2. The density (d, g / cm

  20. Dissolved effluent organic matter: Characteristics and potential implications in wastewater treatment and reuse applications.

    Science.gov (United States)

    Michael-Kordatou, I; Michael, C; Duan, X; He, X; Dionysiou, D D; Mills, M A; Fatta-Kassinos, D

    2015-06-15

    Wastewater reuse is currently considered globally as the most critical element of sustainable water management. The dissolved effluent organic matter (dEfOM) present in biologically treated urban wastewater, consists of a heterogeneous mixture of refractory organic compounds with diverse structures and varying origin, including dissolved natural organic matter, soluble microbial products, endocrine disrupting compounds, pharmaceuticals and personal care products residues, disinfection by-products, metabolites/transformation products and others, which can reach the aquatic environment through discharge and reuse applications. dEfOM constitutes the major fraction of the effluent organic matter (EfOM) and due to its chemical complexity, it is necessary to utilize a battery of complementary techniques to adequately describe its structural and functional character. dEfOM has been shown to exhibit contrasting effects towards various aquatic organisms. It decreases metal uptake, thus potentially reducing their bioavailability to exposed organisms. On the other hand, dEfOM can be adsorbed on cell membranes inducing toxic effects. This review paper evaluates the performance of various advanced treatment processes (i.e., membrane filtration and separation processes, activated carbon adsorption, ion-exchange resin process, and advanced chemical oxidation processes) in removing dEfOM from wastewater effluents. In general, the literature findings reveal that dEfOM removal by advanced treatment processes depends on the type and the amount of organic compounds present in the aqueous matrix, as well as the operational parameters and the removal mechanisms taking place during the application of each treatment technology. PMID:25917290

  1. Preliminary description of hydrologic characteristics and contaminant transport potential of rocks in the Pasco Basin, south-central Washington

    International Nuclear Information System (INIS)

    This report aims at consolidating existing data useful in defining the hydrologic characteristics of the Pasco Basin within south-central Washington. It also aims at compiling the properties required to evaluate contaminant transport potential within individual subsurface strata in this basin. The Pasco Basin itself is a tract of semi-arid land covering about 2,000 square miles in south-central Washington. The regional geology of this basin is dominated by tholeiitic flood basalts of the Columbia Plateau. The surface hydrology of the basin is dominated by the Yakima, Snake, and Columbia rivers. Short-lived ephemeral streams may flow for a short period of time after a heavy rainfall or snowmelt. The subsurface hydrology of the Pasco Basin is characterized by an unconfined aquifer carrying the bulk of the water discharged within the basin. This aquifer overlies a series of confined aquifers carrying progressively smaller amounts of groundwater as a function of depth. The hydraulic properties of the various aquifers and non-water-bearing strata are characterized and reported. A summary of the basic properties is tabulated. The hydrochemical data obtained are summarized. The contaminant transport properties of the rocks in the Pasco Basin are analyzed with emphasis on the dispersion and sorption coefficients and the characteristics of the potential reactions between emplaced waste and the surrounding medium. Some basic modeling considerations of the hydrogeologic systems in the basin with a brief discussion of model input requirements and their relationship to available data are presented

  2. Risk factors and psychosocial characteristics of potential problematic and problematic internet use among adolescents: A cross-sectional study

    Directory of Open Access Journals (Sweden)

    Tsitsika Artemis

    2011-07-01

    Full Text Available Abstract Background Problematic internet use (PIU is associated with a plethora of psychosocial adversities. The study objectives were to assess the determinants and psychosocial implications associated with potential PIU and PIU among adolescents. Methods A cross-sectional study design was applied among a random sample (n = 866 of Greek adolescents (mean age: 14.7 years. Self-completed questionnaires, including internet use characteristics, Young Internet Addiction Test, and Strengths and Difficulties Questionnaire, were utilized to examine the study objectives. Results Among the study population, the prevalence rates of potential PIU and PIU were 19.4% and 1.5%, respectively. Multinomial logistic regression indicated that male gender (Odds Ratio, OR: 2.01; 95% Confidence Interval, 95% CI: 1.35-3.00, as well as utilizing the internet for retrieving sexual information (OR: 2.52; 95% CI: 1.53-4.12, interactive game playing (OR: 1.85; 95% CI: 1.21-2.82, and socialization, including chat-room use (OR: 1.97; 95% CI: 1.36-2.86 and email (OR: 1.53; 95% CI: 1.05-2.24, were independently associated with potential PIU and PIU. Adolescents with potential PIU had an increased likelihood of concomitantly presenting with hyperactivity (OR: 4.39; 95% CI: 2.03-9.52 and conduct (OR: 2.56; 95% CI: 1.46-4.50 problems. Moreover, adolescent PIU was significantly associated with hyperactivity (OR: 9.96; 95% CI: 1.76-56.20 and conduct (OR: 8.39; 95% CI: 2.04-34.56 problems, as well as comprehensive psychosocial maladjustment (OR: 8.08; 95% CI: 1.44-45.34. Conclusions The determinants of potential PIU and PIU include accessing the internet for the purposes of retrieving sexual information, game playing, and socialization. Furthermore, both potential PIU and PIU are adversely associated with notable behavioral and social maladjustment among adolescents.

  3. Characteristics of brainstem auditory evoked potential of neonates with mild or moderate hyperbilirubinemia

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    BACKGROUND: Brainstem auditory evoked potential (BAEP) has been widely used to evaluate the functional integrity and development of injured auditory system and brain, especially to objectively evaluate the function of auditory system and brain stem of very young babies, such as neonates and sick babies.OBJECTIVE: To observe the changes of BAEP of neonates with hyperbilirubinemia, and to investigate the relationship of bilirubin concentration and BAEP.DESIGN: An observation experiment.SETTING: Department of Pediatrics, the 309 Clinical Division, General Hospital of Chinese PLA.PARTICIPANTS: Fifty-eight neonates with mild or moderate hyperbilirubinemia exhibiting jaundice within 24 hours after born, who received the treatment in the Department of Pediatrics, the 309 Clinical Division, General Hospital of Chinese PLA between January 2004 and May 2007, were recruited in this study. The involved neonates, 31 boys and 27 girls, had gestational age of 37 to 46 weeks. They had no history of birth asphyxia, and were scored 8 to 10 points when born. Written informed consents of examination and treatment were obtained from the guardians of the neonates. This study was approved by the Hospital Ethics Committee. According to serum total bilirubin value, the neonates were assigned into 3 groups: low-concentration bilirubin group (n =16), moderate-concentration bilirubin group (n =27) and high-concentration bilirubin group (n =15). According to mean daily bilirubin increase, the subjects were sub-assigned into bilirubin rapid increase group (n =39) and bilirubin slow increase group (n =19).METHODS: After admission, all the neonates received drug treatment. Meanwhile, their 116 ears were examined with a myoelectricity evoked potential equipment (KEYPOINT) in latency, wave duration,amplitude and wave shape differentiation of each wave of BAEP. BAEP abnormal type was observed and abnormal rate of BAEP was calculated.MAIN OUTCOME MEASURES: ① Abnormal rate and abnormal type of BAEP

  4. [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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. CHARACTERISTICS OF COMPOSTED BIO-TOILET RESIDUE AND ITS POTENTIAL USE AS A SOIL CONDITIONER

    Directory of Open Access Journals (Sweden)

    Jovita Triastuti

    2016-10-01

    Full Text Available Bio-toilet is a dry toilet where human excreta is trapped in a lignocelluloses soil matrix such as wood sawdust, then it is decomposed by aerobic  bacteria to organic compost rich in minerals such as N, P, and K. The study aimed to characterize the bio-toilet residue and its potential use as a soil conditioner for Jatropha curcas. The study was conducted in a private school of Daarut Tauhid in Bandung West Java. A bio-toilet S-50 type of Japan was constructed consisting of a composting chamber, mixer, heater, exhaust fan, and closet. The composting chamber was filled with 63 kg of Albizzia sawdust. Feces and urine was loaded daily by 54 students for 122-day observation. At the end of observation, the decomposed bio-toilet residue was evaluated for its physical properties such as bulk density (rb, porosity (%, and water retention (WR. Chemical properties such as pH, C/N ratio, N, P, and K, as well as microbiological properties such as numbers of bacteria, fungi, and worm eggs were evaluated at 14 and 122 days of decomposition process. Effect of the composted bio-toilet residue as plant growth media was evaluated using J. curcass as a plant indicator. Before it was used as a growth media, the composted bio-toilet residue was dried in a room temperature for 30 days. The experiment was designed in a completely randomized design 2 x 4 factorial with three replications. The first factor was the rate of composted biotoilet residue, i.e., 0, 20, 40, and 60% based on weight of the growth media mixture (1500 g pot-1, and the second was NPK fertilizer addition at 0 and 2 g pot-1. Each pot was planted with 2-month old of J. curcas seedlings. Parameters evaluated were leaf number, leaf area, stem height, and stem diameter measured at 12 weeks after planting. The results showed that the biotoilet residue was suitable as soil conditioner because it had high porosity (76%, low bulk density (0.19 g cm-3, high water retention (2.6 ml g-1 DM, neutral pH (6.9, C

  10. 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.

  11. 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.

  12. 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

  13. Geothermal systems in volcanic arcs: Volcanic characteristics and surface manifestations as indicators of geothermal potential and favorability worldwide

    Science.gov (United States)

    Stelling, P.; Shevenell, L.; Hinz, N.; Coolbaugh, M.; Melosh, G.; Cumming, W.

    2016-09-01

    This paper brings a global perspective to volcanic arc geothermal assessments by evaluating trends and correlations of volcanic characteristic and surface manifestation data from world power production sites in subduction zone volcanic settings. The focus of the work was to evaluate volcanic centers individually and as a group in these arcs by correlating various geologic characteristics with known potential to host electricity grade geothermal systems at the volcanic centers. A database was developed that describes key geologic factors expected to be indicative of productive geothermal systems in a global training set, which includes all 74 subduction zone volcanic centers world-wide with current or proven power production capability. Importantly, this data set only contains data from subduction zone volcanoes and contains no negative cases, limiting the populations of any statistical groups. Regardless, this is the most robust geothermal benchmark training set for magmatic-heated systems to date that has been made public. The work reported here is part of a larger project that included data collection, evaluation, correlations and weightings, fairway and favorability modeling and mapping, prediction of blind systems, and uncertainty analysis to estimate errors associated with model predictions. This first paper describes volcano characteristics, compositions and eruption ages and trends along with surface manifestation observations and temperatures as they relate to known power producing systems. Our findings show a strong correlation between the presence and size of active flank fumarole areas and installed power production. Additionally, the majority of volcanic characteristics, including long-held anecdotal correlations related to magmatic composition or size, have limited to no correlation with power production potential. Notable exceptions are correlations between greater power yield from geothermal systems associated with older (Pleistocene) caldera systems

  14. [Influence of Medication on the Oscillatory and Dynamic Characteristics of Subthalamic Local Field Potentials in Patients with Parkinson's Disease].

    Science.gov (United States)

    Wang, Yanan; Geng, Xinyi; Huang, Yongzhi; Wang, Shouyan

    2016-02-01

    The dysfunction of subthalamic nucleus is the main cause of Parkinson's disease. Local field potentials in human subthalamic nucleus contain rich physiological information. The present study aimed to quantify the oscillatory and dynamic characteristics of local field potentials of subthalamic nucleus, and their modulation by the medication therapy for Parkinson's disease. The subthalamic nucleus local field potentials were recorded from patients with Parkinson's disease at the states of on and off medication. The oscillatory features were characterised with the power spectral analysis. Furthermore, the dynamic features were characterised with time-frequency analysis and the coefficient of variation measure of the time-variant power at each frequency. There was a dominant peak at low beta-band with medication off. The medication significantly suppressed the low beta component and increased the theta component. The amplitude fluctuation of neural oscillations was measured by the coefficient of variation. The coefficient of variation in 4-7 Hz and 60-66 Hz was increased by medication. These effects proved that medication had significant modulation to subthalamic nucleus neural oscillatory synchronization and dynamic features. The subthalamic nucleus neural activities tend towards stable state under medication. The findings would provide quantitative biomarkers for studying the mechanisms of Parkinson's disease and clinical treatments of medication or deep brain stimulation. PMID:27382739

  15. [Distribution Characteristics and Potential Ecological Hazards Assessment of Soil Heavy Metals in Typical Soil Profiles in Southeast Suburb of Beijing].

    Science.gov (United States)

    Zhao, Qian; Ma, Lin; Liu, Yi-fei; He, Jiang-tao; Li, Guang-he

    2016-05-15

    To investigate the distribution characteristics and the potential ecology risk of different types of heavy metals, soil samples were collected from various stratigraphic sections in the southeastern suburb of Beijing, where soil heavy metal (Cu, Pb, Cr, As) contents were measured and analyzed using multivariate statistical analysis and the potential ecological risk index method. The results showed that the concentrations of the four heavy metals followed the order of Cr > Cu > As > Pb with variable coefficients ranging from 59.60% to 159.33% at 3-6 m stratum, which all displayed a high degree of variability. The concentrations of Cu and Pb were positively correlated with soil organic matter (SOM), cation exchange capacity (CEC), etc, with higher eigenvalues in Factor 1 and 2, demonstrating the impact of organic colloid on the occurrence of heavy metals. The risk level of the specific heavy metal followed the order of As > Cu > Pb > Cr, where As already showed a medium potential ecological risk in the studied area. PMID:27506050

  16. [Distribution Characteristics and Potential Ecological Hazards Assessment of Soil Heavy Metals in Typical Soil Profiles in Southeast Suburb of Beijing].

    Science.gov (United States)

    Zhao, Qian; Ma, Lin; Liu, Yi-fei; He, Jiang-tao; Li, Guang-he

    2016-05-15

    To investigate the distribution characteristics and the potential ecology risk of different types of heavy metals, soil samples were collected from various stratigraphic sections in the southeastern suburb of Beijing, where soil heavy metal (Cu, Pb, Cr, As) contents were measured and analyzed using multivariate statistical analysis and the potential ecological risk index method. The results showed that the concentrations of the four heavy metals followed the order of Cr > Cu > As > Pb with variable coefficients ranging from 59.60% to 159.33% at 3-6 m stratum, which all displayed a high degree of variability. The concentrations of Cu and Pb were positively correlated with soil organic matter (SOM), cation exchange capacity (CEC), etc, with higher eigenvalues in Factor 1 and 2, demonstrating the impact of organic colloid on the occurrence of heavy metals. The risk level of the specific heavy metal followed the order of As > Cu > Pb > Cr, where As already showed a medium potential ecological risk in the studied area.

  17. 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

  18. 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

  19. 蝙蝠葛苏林碱对家兔在体心脏单相动作电位的影响%Effect of daurisoline on monophasic action potential of rabbit hearts in vivo

    Institute of Scientific and Technical Information of China (English)

    李真; 林先明; 夏敬生; 杨晓燕; 龚培力; 曾繁典

    2001-01-01

    The use-dependent characteristics of daurisoline on monophasic action potentials (MAP) of the left ventricle of the rabbit heart in situ were recorded with MAP recording technique. The results showed that daurisoline decreased monophasic action potential amplitude (MAPA) and prolonged monophasic action potential duration at the 50% and 90% (MAPD50, MAPD90), effective refractory period (ERP), ERP/MAPD90 at the steady-state cycle lengths of 240, 210, 180 ms. The percent of prolongation of MAPD50 was 12.8±2.9, 9.5±2.6, 9.0±1.6, that of MAPD90 was 10.9±2.6, 7.5±2.4, 6.5±2.7, that of ERP was 25.7±4.3, 18.5±4.1, 24.2±7.2, and that of ERP/MAPD90 was 13.7±4.5, 10.2±2.2, 16.1±5.1, respectively. Its effect showed no relation to frequency (n=6, P>0.05). The effects of sotalol on MAP were similar to that of daurisoline, but it prolonged MAPD90 and ERP in a reverse use-dependent manner (P0.05). 其延长作用均呈非使用依赖性特征. 在所有起搏周长下,索他洛尔亦降低MAPA,延长MAPD50,MAPD90,ERP,ERP/MAPD90,但其延长MAPD90,ERP的作用均呈逆向使用依赖性特征(P<0.05). 结果表明,DS能明显降低家兔在体心脏MAPA,延长MAPD50,MAPD90,ERP,ERP/MAPD90,该作用呈非使用依赖性特征.

  20. 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

  1. 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.

  2. Spectral Fingerprinting: The potential of VNIR-SWIR spectral characteristics for tracing sediment sources in a Spanish mesoscale catchment

    Science.gov (United States)

    Brosinsky, Arlena; Foerster, Saskia; Segl, Karl; Bronstert, Axel; Kaufmann, Hermann; Lopéz-Tarazón, José-Andrés

    2014-05-01

    Knowledge on the origin of suspended sediment can greatly facilitate erosion prevention and thus sustainable watershed management. One approach providing information on the origin of suspended sediments is the fingerprinting technique. It is based on the assumption that potential sediment sources can be discriminated and that the contribution of these sources to the sediment can be determined on the basis of distinctive characteristics (fingerprints). Recent studies indicate that VNIR-SWIR reflectance characteristics of soil may be a rapid, inexpensive alternative to traditional fingerprinting properties such as e.g. geochemical composition. In this study, we aim at further assessing the potential of this innovative sediment tracing technique, specifically whether (a) potential sediment sources can be reliably identified based on spectral features, (b) field derived source information (more rapid) is sufficient for spectral fingerprinting, (c) spectral fingerprints permit the quantification of source contribution, and (d) to examine changes in the relative contributions from different sources both, between and within individual storm events. Therefore, samples were collected in the Isábena catchment (445 km²) in the central Spanish Pyrenees: 1) soil samples from the main potential source areas and 2) suspended sediment samples during four flood events in autumn 2011 and spring 2012 at the catchment outlet and at several subcatchment outlets. In addition, 3) artificial mixtures of known proportions were produced from soil samples for testing of key assumptions in a controlled environment. Soil samples (1) were spectrally measured in the field using an ASD spectrometer and subsequently all samples (1-3) were dried and spectrally measured in the laboratory using the same equipment. Colour parameters and physically based features with relation to organic carbon, iron oxide and clay content were calculated from field- and laboratory spectra. Principal component

  3. Potential therapeutic radiotracers: preparation, biodistribution and metabolic characteristics of 177Lu-labeled cyclic RGDfK dimer.

    Science.gov (United States)

    Shi, Jiyun; Liu, Zhaofei; Jia, Bing; Yu, Zilin; Zhao, Huiyun; Wang, Fan

    2010-06-01

    In this study, we reported the preparation and evaluation of (177)Lu-DOTA-RGD2, (177)Lu-DOTA-Bz-RGD2 and (177)Lu-DTPA-Bz-RGD2 (RGD2 = E[c(RGDfK)](2)) as a potential therapeutic radiotracers for the treatment of integrin alpha(v)beta(3)-positive tumors. The BALB/c nude mice bearing the U87MG human glioma xenografts were used to evaluate the biodistribution characteristics and excretion kinetics of (177)Lu-DOTA-RGD2, (177)Lu-DOTA-Bz-RGD2 and (177)Lu-DTPA-Bz-RGD2. It was found that there were no major differences in their lipophilicity and biodistribution characteristics, particularly at latter time points. A major advantage of using DTPA-Bz as the bifunctional chelator (BFC) was its high radiolabeling efficiency (fast and high yield radiolabeling) at room temperature. Using DOTA and DOTA-Bz as BFCs, the radiolabeling kinetics was slow, and heating at 100 degrees C and higher DOTA-conjugate concentration were needed for successful (177)Lu-labeling. Therefore, DTPA-Bz is an optimal BFC for routine preparation of (177)Lu-labeled cyclic RGDfK peptides, and (177)Lu-DTPA-Bz-RGD2 is worthy of further investigation for targeted radiotherapy of integrin alpha(v)beta(3)-positive tumors.

  4. THE CHARACTERISTICS OF THE SELF-SUPPORT STILT-HOUSES TOWARDS THE DISASTER POTENTIALITY AT THE CAMBAYA COASTAL AREA, MAKASSAR

    Directory of Open Access Journals (Sweden)

    Isfa Sastrawati

    2009-01-01

    Full Text Available Self-support stilt-houses at the coastal area have environment characteristics that are different from inland houses, and they have the disaster potentiality such as hurricanes, tidal waves, abrasion, earthquakes, and even tsunami. The stilt houses are very adaptable to climatic conditions and coastal disasters. The shape of the stilt houses at the coastal area must comply with aspects of safety, security, comfort, and health. This paper examines the characteristics of the stilt houses at the coastal area of Cambaya, Makassar, especially in terms of safety and security aspects. The aspects of safety and security include the resistance of the building construction towards disasters. Along with the development of the urban area, the demanding needs and limited financial-abilities, the owners of the houses at the Cambaya coastal area develop their houses by utilizing the empty space at the coastal area and the space under floor of the stilt house. The change of the building shape gives an effect on the poor quality of the building, building safety, and security. However, there are several stilt houses at Cambaya which could reduce the impacts of disasters on the safety of the residents through their local wisdom.

  5. Recruitment of Engaged Couples for Premarital Counseling: An Empirical Examination of the Importance of Program Characteristics and Topics to Potential Participants.

    Science.gov (United States)

    Sullivan, Kieran T.; Anderson, Carmen

    2002-01-01

    Study seeks to understand what potential participants perceive are attractive characteristics in premarital prevention approaches. Results indicate that leader characteristics, content, and topics such as communication, finances, and problem solving are the most important elements of premarital counseling to couples. Differences based on gender…

  6. 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.

  7. 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...

  8. 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.

  9. 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.

  10. Characteristics of Lactic Acid Bacteria Isolated from Gastrointestinal Tract of Cemani Chicken and Their Potential Use as Probiotics

    Directory of Open Access Journals (Sweden)

    S. N. Jannah

    2014-12-01

    Full Text Available The aims of this study were to screen and characterize lactic acid bacteria (LAB isolated from gastrointestinal (GI tract of Cemani chicken, one of Indonesian local chicken and to investigate their potential use as probiotics. LAB were isolated from GI tract using MRSA and GYPA media and incubated anaerobically. Selected LAB were determined their probiotic properties with several assays. Identification of selected LAB was based on 16S rDNA sequences, morphological and biochemical characteristics. Ninety five bacteria were isolated and characterized as lactic acid bacteria (Gram positive, catalase negative, non sporeforming and acid producing. Twenty four isolates of LAB demonstrated antimicrobial activity against Escherichia coli JCM 1649 and Salmonella enteritidis B2586, and three selected isolates, i.e. CCM011, CSP004, and CVM002 showed the highest inhibition activity. The isolates had characters of high cell surface hydrophobicity and inter-isolate coaggregation ability of LAB, high survival at low pH, high phytase and protease activity (but no amylase and lipase activity, weak coaggregation with pathogen and no resistance to the examined antibiotics. The isolates were identified based on sequence analysis of 16S rRNA gene as Lactobacillus salivarius, however, each isolate had different profiles of sugar fermentation. Therefore the three LAB isolates had potential application as probiotics for chicken.

  11. Experimental investigation of the quality characteristics of agricultural plastic wastes regarding their recycling and energy recovery potential.

    Science.gov (United States)

    Briassoulis, D; Hiskakis, M; Babou, E; Antiohos, S K; Papadi, C

    2012-06-01

    A holistic environmentally sound waste management scheme that transforms agricultural plastic waste (APW) streams into labelled guaranteed quality commodities freely traded in open market has been developed by the European research project LabelAgriWaste. The APW quality is defined by the APW material requirements, translated to technical specifications, for recycling or energy recovery. The present work investigates the characteristics of the APW quality and the key factors affecting it from the introduction of the virgin product to the market to the APW stream reaching the disposer. Samples of APW from different countries were traced from their application to the field through their storage phase and transportation to the final destination. The test results showed that the majority of APW retained their mechanical properties after their use preserving a "very good quality" for recycling in terms of degradation. The degree of soil contamination concerning the APW recycling and energy recovery potential fluctuates depending on the agricultural plastic category and application. The chlorine and heavy metal content of the tested APW materials was much lower than the maximum acceptable limits for their potential use in cement industries.

  12. Equine Adipose-Derived Mesenchymal Stem Cells: Phenotype and Growth Characteristics, Gene Expression Profile and Differentiation Potentials

    Directory of Open Access Journals (Sweden)

    Faezeh Alipour

    2015-01-01

    Full Text Available Objective: Because of the therapeutic application of stem cells (SCs, isolation and characterization of different types of SCs, especially mesenchymal stem cells (MSCs, have gained considerable attention in recent studies. Adipose tissue is an abundant and accessible source of MSCs which can be used for tissue engineering and in particular for treatment of musculoskeletal disorders. This study was aimed to isolate and culture equine adipose-derived MSCs (AT-MSCs from little amounts of fat tissue samples and determine some of their biological characteristics. Materials and Methods: In this descriptive study, only 3-5 grams of fat tissue were collected from three crossbred mares. Immediately, cells were isolated by mechanical means and enzymatic digestion and were cultured in optimized conditions until passage 3 (P3. The cells at P3 were evaluated for proliferative capacities, expression of specific markers, and osteogenic, chondrogenic and adipogenic differentiation potentials. Results: Results showed that the isolated cells were plastic adherent with a fibroblast-like phenotype. AT-MSCs exhibited expression of mesenchymal cluster of differentiation (CD markers (CD29, CD44 and CD90 and not major histocompatibility complex II (MHC-II and CD34 (hematopoietic marker. Cellular differentiation assays demonstrated the chondrogenic, adipogenic and osteogenic potential of the isolated cells. Conclusion: Taken together, our findings reveal that equine MSCs can be obtained easily from little amounts of fat tissue which can be used in the future for regenerative purposes in veterinary medicine.

  13. 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.

  14. Energy consumption practices of rural households in north China: Basic characteristics and potential for low carbon development

    International Nuclear Information System (INIS)

    Reducing the climate impact of rural household energy consumption in China is complicated since it is bound up with deeply routinized daily practices and dependent from existing infrastructural systems of energy supply. To assess the potential for low carbon development we first estimate the overall CO2 emissions of rural households, followed by a more in depth description and characterization of the different energy use practices within the households. Space heating turns out to be the largest emission source among domestic energy practices in north China. We present lifestyle and context related factors that help to explain existing differences in domestic energy use practices of households. The potential for low carbon development is discussed both at the demand side and the supply side. At the demand side, the use of more efficient technologies and cleaner energy sources for space heating seems to be a high potential measure for achieving low carbon households. At the supply side the reduction of rural domestic CO2 emissions could be effectively supported by making available to householders renewable and cleaner energy sources and technologies. In order to be effective, such low carbon energy options should take into account the (income) characteristics and lifestyles of rural householders. - Highlights: ► Rural household energy use and CO2 emissions in China are investigated via a field survey. ► Energy use and CO2 emissions are related to separate practices within households. ► Improvements in CO2 emission reduction are possible at demand side and supply side. ► Income and education are proven to be positively correlated with household emissions

  15. Significance of frost action and surface soil characteristics to wind erosion at Rocky Flats, Colorado. Second progress report, October 1, 1975--May 30, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Caine, N.; Morin, P.

    1976-01-01

    This report summarizes information on soil frost effects collected on Rocky Flats during the 1975-1976 winter. On a broad scale, work on soil textures at and just below the ground surface corroborates the conclusion reached earlier that the general frost susceptibility of the Rocky Flats soils is quite well keyed to topography. This is incorporated into a mapping procedure for potential soil frost activity which is applied to the northwestern part of the Rocky Flats area. On a site scale, instrumental records of weather conditions and soil responses have been maintained from October, 1975, to May, 1976, at the Lindsay Ranch study site, northwest of the Rocky Flats Plant. During that period, 33 needle ice events have been observed and recorded and are described in this report. A preliminary examination of wind data for the same period suggests that the soil in areas of natural vegetation on the site are not exposed to wind action. If, however, they were exposed, winds capable of eroding them are common.

  16. 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.

  17. Experimental investigation of the quality characteristics of agricultural plastic wastes regarding their recycling and energy recovery potential

    International Nuclear Information System (INIS)

    Highlights: ► Definition of parameters characterising agricultural plastic waste (APW) quality. ► Analysis of samples to determine APW quality for recycling or energy recovery. ► Majority of APW samples from various countries have very good quality for recycling. ► Upper limit of 50% w/w soil contamination in APW acceptable for energy recovery. ► Chlorine and heavy metals content in APW below the lowest limit for energy recovery. - Abstract: A holistic environmentally sound waste management scheme that transforms agricultural plastic waste (APW) streams into labelled guaranteed quality commodities freely traded in open market has been developed by the European research project LabelAgriWaste. The APW quality is defined by the APW material requirements, translated to technical specifications, for recycling or energy recovery. The present work investigates the characteristics of the APW quality and the key factors affecting it from the introduction of the virgin product to the market to the APW stream reaching the disposer. Samples of APW from different countries were traced from their application to the field through their storage phase and transportation to the final destination. The test results showed that the majority of APW retained their mechanical properties after their use preserving a “very good quality” for recycling in terms of degradation. The degree of soil contamination concerning the APW recycling and energy recovery potential fluctuates depending on the agricultural plastic category and application. The chlorine and heavy metal content of the tested APW materials was much lower than the maximum acceptable limits for their potential use in cement industries.

  18. Cadmium accumulation characteristics and removal potentials of high cadmium accumulating rice line grown in cadmium-contaminated soils.

    Science.gov (United States)

    Tang, Hao; Li, Tingxuan; Yu, Haiying; Zhang, Xizhou

    2016-08-01

    Phytoextraction is a promising technique to remove cadmium (Cd) from contaminated soils. In this research, the two different Cd accumulation rice lines of Lu527-8 (the high Cd accumulating rice line) and Lu527-4 (the normal rice line) were grown in soils with different Cd treatments (0, 5, 10, and 20 mg kg(-1) soil) to evaluate Cd accumulation characteristics and Cd removal potentials. When the concentration of Cd in soil increased, Lu527-8 showed less symptoms of phytotoxicity when compared to Lu527-4. Furthermore, Lu527-8 demonstrated greater shoot Cd accumulation (321.17-964.95 mg plant(-1)) than Lu527-4 (50.37-201.66 μg plant(-1)) at the jointing and filling stages. The soil available Cd content of Lu527-8 significantly decreased by 26.92-38.97 and 27.77-63.44 % at the jointing and filling stages, respectively. Meanwhile, the total Cd content in soil also reduced by 11.64-46.75 and 21.41-54.11 % at jointing and filling stages, respectively. When the Cd concentration in soil was 20 mg kg(-1), the Cd extraction rate in shoots of Lu527-8 reached 2.12 and 2.85 % which increased 10.60 and 6.48 times compared with that of Lu527-4 at the jointing and filling stages, respectively. In conclusion, this study demonstrates that Lu527-8 shows great abilities of Cd accumulation and Cd removal potential from contaminated soils with different Cd treatments and it is a promising species for phytoextraction of Cd-contaminated soils.

  19. Variations in spectroscopic characteristics and disinfection byproduct formation potentials of dissolved organic matter for two contrasting storm events

    Science.gov (United States)

    Nguyen, Hang Vo-Minh; Lee, Mi-Hee; Hur, Jin; Schlautman, Mark A.

    2013-02-01

    SummaryChanges in disinfection byproduct (DBP) precursors during storm events have not been intensively studied to date despite their dramatic impact on downstream drinking water supplies. For this study, variations in dissolved organic matter (DOM) spectroscopic properties and DBP formation potentials (DBPFPs), and the correlations among these various parameters, were investigated in river water samples collected under two contrasting storm event conditions (a strong summer storm versus a weak fall event). Fluorescence excitation-emission matrices (EEMs) combined with parallel factor analysis revealed that a combination of two humic-like components (C1 and C2) dominated the EEM data of the storm samples. Measured DOM characteristics and DBPFPs varied over a wider range during the more intense summer storm, exhibiting higher values of specific ultraviolet absorbance and C1/C2 ratio at high flow conditions. Variations in the fluorescence index were less pronounced during the two storm events. The spectroscopic changes were well explained by the input of terrestrial DOM sources from the surrounding catchments during the storms. Different trends of the formation potentials for trihalomethanes and haloacetic acids on the recession limb of the hydrographs suggest that the structures responsible for DBP precursors during storm events may not be the same for the two classes of DBPs. The ultraviolet light-absorbing moieties in DOM appear to play major roles in generating DBPs, as evidenced by their strong positive correlations with DBPFPs. Higher correlations with DBPFP for C1 versus C2 suggest that humic-like substances associated with more aromatic and condensed structures have a greater proclivity to generate DBP upon chlorination.

  20. Characteristics of Hydroxypropyl Starch of Sorghum Mutant Line Zh-30 and its Potential use in Paper Industry

    International Nuclear Information System (INIS)

    Sorghum mutant line Zh-30 is a breeding line developed at the Center for the Application of Isotope and Radiation Technology, BATAN by using mutation techniques. Gamma Irradiation with the dose of 300 Gy was used to induced plant genetic variability. Through selection processes in several generations, the mutant line Zh-30 was identified to have better agronomic characteristics, better grain quality and higher yield than the original variety. Research on starch quality of this mutant line was done to identify its potential use in a paper industry. Hydroxypropyl starch derivatives of this sorghum lines were prepared by varying alkalinity of the reaction mixtures using propylene oxide to reach Molar of Substitution (MS) of 0-0.180. Its pasting behavior, paste properties and application in wet end paper processing were evaluated. The optimal amount of addition of hydroxypropyl starch was 1-2 %. At this level, drainage time was lower, so that it decreased paper machine speed. At higher level, it did not improve the burst and tensile strengths but tended to decrease the tear strength of handsheets. The properties of lower pasting temperature, higher water holding capacity lower retrogradation susceptibility, increased viscosity and stability of pastes suggested that hydroxypropyl starch of sorghum Zh-30 was suitable for use in wet end paper processing. Comparing to the original starch, the hydroxypropyl starch of sorghum Zh-30 could significantly improve the strength of handsheets. (author)

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Kavain, the Major Constituent of the Anxiolytic Kava Extract, Potentiates GABAA Receptors: Functional Characteristics and Molecular Mechanism

    Science.gov (United States)

    Chua, Han Chow; Christensen, Emilie T. H.; Hoestgaard-Jensen, Kirsten; Hartiadi, Leonny Y.; Ramzan, Iqbal; Jensen, Anders A.; Absalom, Nathan L.; Chebib, Mary

    2016-01-01

    Extracts of the pepper plant kava (Piper methysticum) are effective in alleviating anxiety in clinical trials. Despite the long-standing therapeutic interest in kava, the molecular target(s) of the pharmacologically active constituents, kavalactones have not been established. γ-Aminobutyric acid type A receptors (GABAARs) are assumed to be the in vivo molecular target of kavalactones based on data from binding assays, but evidence in support of a direct interaction between kavalactones and GABAARs is scarce and equivocal. In this study, we characterised the functional properties of the major anxiolytic kavalactone, kavain at human recombinant α1β2, β2γ2L, αxβ2γ2L (x = 1, 2, 3 and 5), α1βxγ2L (x = 1, 2 and 3) and α4β2δ GABAARs expressed in Xenopus oocytes using the two-electrode voltage clamp technique. We found that kavain positively modulated all receptors regardless of the subunit composition, but the degree of enhancement was greater at α4β2δ than at α1β2γ2L GABAARs. The modulatory effect of kavain was unaffected by flumazenil, indicating that kavain did not enhance GABAARs via the classical benzodiazepine binding site. The β3N265M point mutation which has been previously shown to profoundly decrease anaesthetic sensitivity, also diminished kavain-mediated potentiation. To our knowledge, this study is the first report of the functional characteristics of a single kavalactone at distinct GABAAR subtypes, and presents the first experimental evidence in support of a direct interaction between a kavalactone and GABAARs. PMID:27332705

  7. Action semantics modulate action prediction.

    Science.gov (United States)

    Springer, Anne; Prinz, Wolfgang

    2010-11-01

    Previous studies have demonstrated that action prediction involves an internal action simulation that runs time-locked to the real action. The present study replicates and extends these findings by indicating a real-time simulation process (Graf et al., 2007), which can be differentiated from a similarity-based evaluation of internal action representations. Moreover, results showed that action semantics modulate action prediction accuracy. The semantic effect was specified by the processing of action verbs and concrete nouns (Experiment 1) and, more specifically, by the dynamics described by action verbs (Experiment 2) and the speed described by the verbs (e.g., "to catch" vs. "to grasp" vs. "to stretch"; Experiment 3). These results propose a linkage between action simulation and action semantics as two yet unrelated domains, a view that coincides with a recent notion of a close link between motor processes and the understanding of action language.

  8. 基于IC动作状态的噪声接收特性的探讨∗%Discussion on the Receiving Characteristics of Noise Based on IC Action Status

    Institute of Scientific and Technical Information of China (English)

    樊利军; 魏昊

    2014-01-01

    为了探讨数字设备基于IC动作状态的噪声接收特性,在IC回路外部提供噪声叠加回路,测量此时IC回路中被感应的电压,以此作为噪声接收特性。通过测量倒相IC在电源与接地线之间电磁干扰的接收特性,确认了由倒相IC动作状态所致的噪声接收特性是不同的。结果表明,机器的噪声接收特性有可能受IC动作状态影响,并随时间而发生变化。通过简单的电路仿真也确认了这一结论。%In order to investigate the noise receiving characteristics of digital equipment based on IC action status,the noise superimposed loops is provided outside the IC circuit. The induced voltage in IC circuit is measured at this time,and this voltage is as the noise reception characteristics. By measuring the receiving characteristics of electro-magnetic interference in inverting IC between power and ground lines,the differences of noise reception characteristics caused by different inverting IC action status is confirmed. The results show that,the noise reception characteristics of machine may be affected by IC action status,and may be changed over time. The above conclusion is also confirmed by simple circuit simulation.

  9. Characteristics of Eastern Canadian cultivated Sphagnum and potential use as a substitute for perlite and vermiculite in peat-based horticultural substrates

    OpenAIRE

    M. Aubé; M. Quenum; L.L. Ranasinghe

    2015-01-01

    Sphagnum cultivation on harvested peatlands to meet wetland restoration objectives could be an economically feasible activity since cultivated Sphagnum has potential horticultural applications. We compared the characteristics of cultivated Sphagnum from Shippagan (Canada) with those of non-cultivated Sphagnum products from Chile, New Zealand and Canada, and assessed its potential as a perlite and vermiculite substitute in horticultural peat-based substrates. Shippagan cultivated Sphagnum was ...

  10. Study on seafood volatile profile characteristics during storage and its potential use for freshness evaluation by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhang, Zhuomin; Li, Gongke; Luo, Lin; Chen, Guonan

    2010-02-01

    Seafood volatile profile characteristics at different storage phases are various and can be used for freshness evaluation during storage. It is imperative to obtain the full volatile information prior to the further study of seafood volatile profile characteristics during storage. Also, the efficient data-processing method is another important factor for the interpretation of seafood volatile profile characteristics during storage and related potential volatile markers. In this work, a new analytical strategy, including the efficient sampling technique, sensitive detection and suitable data-processing method, for seafood freshness evaluation was developed based on the volatile profile characteristics during storage. First, the study of volatiles of seafood samples including razor clam, redspot swimming crab and prawn at different storage phases were conducted by headspace solid phase microextraction (HSSPME) followed by gas chromatography-mass spectrometry (GC-MS) detection. Then, seafood volatile profile characteristics at different storage phases were statistically interpreted by a combination data-processing method including normalization, principle component analysis (PCA) and common model strategy. The different seafood volatile profile characteristics and potential volatile markers were attempted to be distilled. The results tentatively suggested that the different seafood volatile profile characteristics during storage could reflect the transitional changing seafood freshness and provide more precise warning information for seafood spoilage during storage than any single chemical markers. This work developed an analytical method for study of seafood volatile profile characteristics and tentatively proposed a new idea of using seafood volatile profile characteristics during storage for the freshness evaluation from the point of view of analytical chemistry. PMID:20103118

  11. Intentional Action and Action Slips.

    Science.gov (United States)

    Heckhausen, Heinz; Beckmann, Jurgen

    1990-01-01

    An explanation of action slips is offered that examines controlled actions in the context of an intentional behavior theory. Actions are considered guided by mentally represented intentions, subdivided into goal intentions and contingent instrumental intentions. Action slips are categorized according to problem areas in the enactment of goal…

  12. Characteristics of soils developed from alluvium and their potential for cocoa plant development in East Kolaka Regency, Southeast Sulawesi

    Directory of Open Access Journals (Sweden)

    E. Yatno

    2016-04-01

    Full Text Available Cocoa is one of plantation commodities that is quite important for the national economy. Land management for the development of this plant should pay attention to the characteristics of the soil. Three soil profiles formed from alluvium parent material in East Kolaka Regency were investigated to determine the mineralogical, physical, and chemical soil properties, as well as the potential of the land for the development of cocoa plant. The results showed that the mineral composition of the sand fraction was dominated by quartz, while the clay mineral fraction was composed of kaolinite, hydrate halloysite, interstratified of illite-vermiculite and smectite. The soils were characterized by poor drainage, low bulk density (0.78 to 0.95 g / cm3, moderate available water pores (10-15%, slow to fast permeability (0.10 to 14.05 cm / h, silty clay loam to silty clay texture of top soil, acidic soil reaction (pH 4.62 to 5.47, high organic C content (3.86 to 4.60% in the top soil and very low organic C content (<0.65% in the lower layer, moderate to high available P (14-38 mg / kg in the A horizon and very low to moderate (1-18 mg / kg in horizon B, moderate to high P2O5 (30-71 mg / 100g in horizon A and extremely low (1-11 mg / 100g in horizon B, very low to moderate K2O (3-28 mg / 100g , moderate to high exchangeable Ca (9.32 to 13.92 cmolc / kg in the upper and lower (0.70 to 5.04 cmolc / kg in the bottom layer, high exchangeable Mg content (2.83 to 8.95 cmolc / kg, high soil CEC (34.18 to 38.28 cmolc / kg in the upper layer and low to moderate (7.87 to 20.39 cmolc / kg in the bottom layer, moderate to high base saturation (44-68%, and very low to moderate Al saturation (0-17%. At the family level, the soil was classified as Fluvaquentic Endoaquepts (EK 1 profile and Typic Endoaquepts (EK 2 and EK 3 profiles, finely loamy, mix, acid, isohypertermik. The land was marginally suitable (S3 for cocoa plant with the contraints of impeded drainage, acid soil

  13. Chlorpyrifos exposure in farmers and urban adults: Metabolic characteristic, exposure estimation, and potential effect of oxidative damage.

    Science.gov (United States)

    Wang, Lei; Liu, Zhen; Zhang, Junjie; Wu, Yinghong; Sun, Hongwen

    2016-08-01

    Chlorpyrifos is a widely used organophosphorus pesticide that efficiently protects crops against pests. However, recent studies suggest that severe exposure to chlorpyrifos may present adverse health effects in human. To analyze the exposure level and metabolic characteristics of chlorpyrifos pesticide in urban adults and farmers with/without occupation pesticide contact, the occurrence of urinary chlorpyrifos and methyl chlorpyrifos (CP-me), as well as their metabolite, 3,5,6-trichloro-2-pyridinol (TCPy), was determined in farmers of an agricultural village in China, and in urban adults of a nearby town. The geometric mean (GM) concentrations of TCPy, which is the major marker of chlorpyrifos exposure, were 4.29 and 7.57μg/g-creatinine in urban adults and farmers before pesticide application, respectively. Chlorpyrifos spraying significantly increased the concentrations of urinary TCPy. In the first day after spraying, a GM concentration of 43.7μg/g-creatinine was detected in the urine specimens from farmers, which decreased to 38.1 and 22.8μg/g-creatinine in the second and third day after chlorpyrifos spraying. The ratio of TCPy and its parent compounds, i.e. chlorpyrifos and CP-me, was positively associated with the sum concentration of urinary chlorpyrifos, CP-me, and TCPy, suggesting the increasing metabolic efficiency of chlorpyrifos to TCPy at higher chlorpyrifos exposure levels. To estimate the farmers' occupational exposure to chlorpyrifos pesticide, a new model based on the fitted first-order elimination kinetics of TCPy was established. Occupational chlorpyrifos exposure in a farmer was estimated to be 3.70μg/kg-bw/day (GM), which is an exposure level that is higher than the recommended guideline levels. Significant increase of urinary 8-hydroxydeoxyguanosine (8-OHdG) was observed on the first day after chlorpyrifos spraying, which indicates a potential oxidative damage in farmers. However, urinary 8-OHdG returned to its baseline level within two

  14. Eugenia uniflora L. Essential Oil as a Potential Anti-Leishmania Agent: Effects on Leishmania amazonensis and Possible Mechanisms of Action

    Directory of Open Access Journals (Sweden)

    Klinger Antonio da Franca Rodrigues

    2013-01-01

    Full Text Available Eugenia uniflora L. is a member of the Myrtaceae family and is commonly known as Brazilian cherry tree. In this study, we evaluated the chemical composition of Eugenia uniflora L. essential oil (EuEO by using gas chromatography-mass spectrometry (GC-MS and assessed its anti-Leishmania activity. We also explored the potential mechanisms of action and cytotoxicity of EuEO. Thirty-two compounds were identified, which constituted 92.65% of the total oil composition. The most abundant components were sesquiterpenes (91.92%, with curzerene (47.3%, γ-elemene (14.25%, and trans-β-elemenone (10.4% being the major constituents. The bioactivity shown by EuEO against promastigotes (IC50, 3.04 μg·mL−1 and amastigotes (IC50, 1.92 μg·mL−1 suggested significant anti-Leishmania activity. In the cytotoxicity determination, EuEO was 20 times more toxic to amastigotes than to macrophages. Hemolytic activity was 63.22% at the highest concentration tested (400 μg·mL−1; however, there appeared to be no toxicity at 50 μg·mL−1. While the data show that EuEO activity is not mediated by nitric oxide production, they do suggest that macrophage activation may be involved in EuEO anti-Leishmania activity, as evidenced by increases in both the phagocytic capacity and the lysosomal activity. More studies are needed to determine in vivo activity as well as additional mechanisms of the anti-Leishmania activity.

  15. Sevoflurane postconditioning alleviates action potential duration shortening and L-type calcium current suppression induced by ischemia/reperfusion injury in rat epicardial myocytes

    Institute of Scientific and Technical Information of China (English)

    GONG Jun-song; YAO Yun-tai; FANG Neng-xin; HUANG Jian; LI Li-huan

    2012-01-01

    Background It has been proved that sevoflurane postconditioning (SpostC) could protect the heart against myocardial ischemia/reperfusion injury,however,there has been few research focused on the electrophysiological effects of SpostC.The objective of the study was to investigate the effects of SpostC on action potential duration (APD) and L-type calcium current (ICa,L) in isolated cardiomyocytes.Methods Langendorff perfused SD rat hearts were randomly assigned to one of the time control (TC),ischemia/reperfusion (I/R,25 minutes of ischemia followed by 30 minutes of reperfusion),and SpostC (postconditioned with 3% sevoflurane) groups.At the end of reperfusion,epicardial myocytes were dissociated enzymatically for patch clamp studies.Results Sevoflurane directly prolonged APD and decreased peak Ica,L densities in epicardial myocytes of the TC group (P<0.05).I/R injury shortened APD and decreased peak Ica,L densities in epicardial myocytes of the I/R group (P<0.05).SpostC prolonged APD and increased peak Ica,L densities in epicardial myocytes exposed to I/R injury (P<0.05).SpostC decreased intracellular reactive oxygen species (ROS) levels,reduced the incidence of ventricular tachycardia and ventricular fibrillation,and decreased reperfusion arrhythmia scores compared with the I/R group (all P<0.05).Conclusions SpostC attenuates APDshortening and ICa,L suppression induced by I/R injury.The regulation of APD and Ica,L by SpostC might be related with intracellular ROS modulation,which contributes to the alleviation of reperfusion ventricular arrhythmia.Chin Med J 2012;125(19):3485-3491

  16. Stochasticity intrinsic to coupled-clock mechanisms underlies beat-to-beat variability of spontaneous action potential firing in sinoatrial node pacemaker cells.

    Science.gov (United States)

    Yaniv, Yael; Lyashkov, Alexey E; Sirenko, Syevda; Okamoto, Yosuke; Guiriba, Toni-Rose; Ziman, Bruce D; Morrell, Christopher H; Lakatta, Edward G

    2014-12-01

    Recent evidence indicates that the spontaneous action potential (AP) of isolated sinoatrial node cells (SANCs) is regulated by a system of stochastic mechanisms embodied within two clocks: ryanodine receptors of the "Ca(2+) clock" within the sarcoplasmic reticulum, spontaneously activate during diastole and discharge local Ca(2+) releases (LCRs) beneath the cell surface membrane; clock crosstalk occurs as LCRs activate an inward Na(+)/Ca(2+) exchanger current (INCX), which together with If and decay of K(+) channels prompts the "M clock," the ensemble of sarcolemmal-electrogenic molecules, to generate APs. Prolongation of the average LCR period accompanies prolongation of the average AP beating interval (BI). Moreover, the prolongation of the average AP BI accompanies increased AP BI variability. We hypothesized that both the average AP BI and AP BI variability are dependent upon stochasticity of clock mechanisms reported by the variability of LCR period. We perturbed the coupled-clock system by directly inhibiting the M clock by ivabradine (IVA) or the Ca(2+) clock by cyclopiazonic acid (CPA). When either clock is perturbed by IVA (3, 10 and 30 μM), which has no direct effect on Ca(2+) cycling, or CPA (0.5 and 5 μM), which has no direct effect on the M clock ion channels, the clock system failed to achieve the basal AP BI and both AP BI and AP BI variability increased. The changes in average LCR period and its variability in response to perturbations of the coupled-clock system were correlated with changes in AP beating interval and AP beating interval variability. We conclude that the stochasticity within the coupled-clock system affects and is affected by the AP BI firing rate and rhythm via modulation of the effectiveness of clock coupling. PMID:25257916

  17. MORPHOLOGICAL CHARACTERISTICS OF POTENTIALLY MALIGNANT PULMONARY NODULES IN HIGH-RISK MALE SMOKERS DETECTED IN LUNG CANCER SCREENING TRIAL IN CRACOW, POLAND

    NARCIS (Netherlands)

    Kiszka, Kinga; Rudnicka-Sosin, Lucyna; Tomaszewska, Romana; Urbanczyk-Zawadzka, Malgorzata; Krupinski, Maciej; Pikul, Patrycja; Podsiadlo, Kaja; Pasowicz, Mieczyslaw; Vliegenthart, Rozemarijn; Oudkerk, Matthijs; Miszalski-Jamka, Tomasz

    2013-01-01

    The purpose of this paper was to present morphological characteristics of potentially malignant nodules revealed in a group of male smokers aged 50-74 with a very high risk for developing lung cancer estimated in the study for lung cancer screening in Cracow (Poland). Nine hundred male smokers aged

  18. A Survey of Nursing Home Organizational Characteristics Associated with Potentially Avoidable Hospital Transfers and Care Quality in One Large British Columbia Health Region

    Science.gov (United States)

    McGregor, Margaret J.; Baumbusch, Jennifer; Abu-Laban, Riyad B.; McGrail, Kimberlyn M.; Andrusiek, Dug; Globerman, Judith; Berg, Shannon; Cox, Michelle B.; Salomons, Kia; Volker, Jan; Ronald, Lisa

    2011-01-01

    Hospitalization of nursing home residents can be futile as well as costly, and now evidence indicates that treating nursing home residents in place produces better outcomes for some conditions. We examined facility organizational characteristics that previous research showed are associated with potentially avoidable hospital transfers and with…

  19. Understanding S-shaped current-voltage characteristics of organic solar cells: Direct measurement of potential distributions by scanning Kelvin probe

    Energy Technology Data Exchange (ETDEWEB)

    Saive, Rebecca, E-mail: rebecca.saive@innovationlab.de; Kowalsky, Wolfgang [InnovationLab GmbH, 69115 Heidelberg (Germany); Institut für Hochfrequenztechnik, TU Braunschweig, 38106 Braunschweig (Germany); Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg (Germany); Mueller, Christian [InnovationLab GmbH, 69115 Heidelberg (Germany); Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg (Germany); Schinke, Janusz; Lovrincic, Robert [InnovationLab GmbH, 69115 Heidelberg (Germany); Institut für Hochfrequenztechnik, TU Braunschweig, 38106 Braunschweig (Germany)

    2013-12-09

    We present a comparison of the potential distribution along the cross section of bilayer poly(3-hexylthiophene)/1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 (P3HT/PCBM) solar cells, which show normal and anomalous, S-shaped current-voltage (IV) characteristics. We expose the cross sections of the devices with a focussed ion beam and measure them with scanning Kelvin probe microscopy. We find that in the case of S-shaped IV-characteristics, there is a huge potential drop at the PCBM/Al top contact, which does not occur in solar cells with normal IV-characteristics. This behavior confirms the assumption that S-shaped curves are caused by hindered charge transport at interfaces.

  20. Loss of ATP-Sensitive Potassium Channel Surface Expression in Heart Failure Underlies Dysregulation of Action Potential Duration and Myocardial Vulnerability to Injury.

    Science.gov (United States)

    Gao, Zhan; Sierra, Ana; Zhu, Zhiyong; Koganti, Siva Rama Krishna; Subbotina, Ekaterina; Maheshwari, Ankit; Anderson, Mark E; Zingman, Leonid V; Hodgson-Zingman, Denice M

    2016-01-01

    The search for new approaches to treatment and prevention of heart failure is a major challenge in medicine. The adenosine triphosphate-sensitive potassium (KATP) channel has been long associated with the ability to preserve myocardial function and viability under stress. High surface expression of membrane KATP channels ensures a rapid energy-sparing reduction in action potential duration (APD) in response to metabolic challenges, while cellular signaling that reduces surface KATP channel expression blunts APD shortening, thus sacrificing energetic efficiency in exchange for greater cellular calcium entry and increased contractile force. In healthy hearts, calcium/calmodulin-dependent protein kinase II (CaMKII) phosphorylates the Kir6.2 KATP channel subunit initiating a cascade responsible for KATP channel endocytosis. Here, activation of CaMKII in a transaortic banding (TAB) model of heart failure is coupled with a 35-40% reduction in surface expression of KATP channels compared to hearts from sham-operated mice. Linkage between KATP channel expression and CaMKII is verified in isolated cardiomyocytes in which activation of CaMKII results in downregulation of KATP channel current. Accordingly, shortening of monophasic APD is slowed in response to hypoxia or heart rate acceleration in failing compared to non-failing hearts, a phenomenon previously shown to result in significant increases in oxygen consumption. Even in the absence of coronary artery disease, failing myocardium can be further injured by ischemia due to a mismatch between metabolic supply and demand. Ischemia-reperfusion injury, following ischemic preconditioning, is diminished in hearts with CaMKII inhibition compared to wild-type hearts and this advantage is largely eliminated when myocardial KATP channel expression is absent, supporting that the myocardial protective benefit of CaMKII inhibition in heart failure may be substantially mediated by KATP channels. Recognition of Ca

  1. Loss of ATP-Sensitive Potassium Channel Surface Expression in Heart Failure Underlies Dysregulation of Action Potential Duration and Myocardial Vulnerability to Injury.

    Directory of Open Access Journals (Sweden)

    Zhan Gao

    Full Text Available The search for new approaches to treatment and prevention of heart failure is a major challenge in medicine. The adenosine triphosphate-sensitive potassium (KATP channel has been long associated with the ability to preserve myocardial function and viability under stress. High surface expression of membrane KATP channels ensures a rapid energy-sparing reduction in action potential duration (APD in response to metabolic challenges, while cellular signaling that reduces surface KATP channel expression blunts APD shortening, thus sacrificing energetic efficiency in exchange for greater cellular calcium entry and increased contractile force. In healthy hearts, calcium/calmodulin-dependent protein kinase II (CaMKII phosphorylates the Kir6.2 KATP channel subunit initiating a cascade responsible for KATP channel endocytosis. Here, activation of CaMKII in a transaortic banding (TAB model of heart failure is coupled with a 35-40% reduction in surface expression of KATP channels compared to hearts from sham-operated mice. Linkage between KATP channel expression and CaMKII is verified in isolated cardiomyocytes in which activation of CaMKII results in downregulation of KATP channel current. Accordingly, shortening of monophasic APD is slowed in response to hypoxia or heart rate acceleration in failing compared to non-failing hearts, a phenomenon previously shown to result in significant increases in oxygen consumption. Even in the absence of coronary artery disease, failing myocardium can be further injured by ischemia due to a mismatch between metabolic supply and demand. Ischemia-reperfusion injury, following ischemic preconditioning, is diminished in hearts with CaMKII inhibition compared to wild-type hearts and this advantage is largely eliminated when myocardial KATP channel expression is absent, supporting that the myocardial protective benefit of CaMKII inhibition in heart failure may be substantially mediated by KATP channels. Recognition of Ca

  2. Regulation of action potential delays via voltage-gated potassium Kv1.1 channels in dentate granule cells during hippocampal epilepsy

    Directory of Open Access Journals (Sweden)

    Florian eKirchheim

    2013-12-01

    Full Text Available Action potential (AP responses of dentate gyrus granule (DG cells have to be tightly regulated to maintain hippocampal function. However, which ion channels control the response delay of DG cells is not known. In some neuron types, spike latency is influenced by a dendrotoxin (DTX-sensitive delay current (ID mediated by unidentified combinations of voltage-gated K+ (Kv channels of the Kv1 family Kv1.1-6. In DG cells, the ID has not been characterized and its molecular basis is unknown. The response phenotype of mature DG cells is usually considered homogenous but intrinsic adaptations likely occur in particular in conditions of hyperexcitability, for example during temporal lobe epilepsy (TLE. In this study, we examined response delays of DG cells and underlying ion channel molecules by employing a new combination of gramicidin-perforated patch-clamp recordings in acute brain slices and single-cell reverse transcriptase quantitative polymerase chain reaction (SC RT-qPCR experiments. An in vivo mouse model of TLE consisting of intrahippocampal kainate (KA injection was used to examine epilepsy-related plasticity. Response delays of DG cells were DTX-sensitive and strongly increased in KA-injected hippocampi; Kv1.1 mRNA was elevated 10-fold, and the response delays correlated with Kv1.1 mRNA abundance on the single cell level. Other Kv1 subunits did not show overt changes in mRNA levels. Kv1.1 immunolabeling was enhanced in KA DG cells. The biophysical properties of ID and the delay heterogeneity between inner and outer DG cell layer were characterized. Using organotypic hippocampal slice cultures (OHCs, where KA incubation also induced ID upregulation, reversibility and neuroprotective potential for DG cells were tested. In summary, the AP timing of DG cells is effectively controlled via scaling of Kv1.1 subunit transcription. With this antiepileptic mechanism, DG cells delay their

  3. Effects of Ascorbic Acid on the Amplitude of Ventral Tegmental Area Field Action Potential in Morphine-Exposed Rats (An Electrophysiology Study

    Directory of Open Access Journals (Sweden)

    K Saadipour

    2010-07-01

    Full Text Available Introduction & Objective: Evidences have indicated that the Ventral Tegmental Area (VTA is the major source of dopamine (DA neurons projecting to cortical and limbic regions involved in cognitive and motivational aspects of addiction. Also, studies have indicated that the Ascorbic acid (vitamin C can reduce the dependency symptoms of opioids such as morphine via effect of activity on dopaminergic neuron in VTA. For this reason, the aim of this study was to assess the effects of ascorbic acid on the amplitude of Ventral Tegmental Area field action potential in morphine-exposed rats. Materials & Methods: Forty male Wistar’s rats were used in this experimental study conducted at Yasuj University of Medical Sciences in 2010. Animals were randomly divided into four groups after electrode implantation and recovery period: 1. No- Vit C and No-Addicted group (nVitC.nA 2. Vit C and No-Addicted group (VitC.nA 3. No- Vit C and Addicted group (nVitCA 4.Vit C and Addicted (VitC.A, The Vit C groups received 500 mg/kg of Vit C during 20 days. For addicted groups morphine was administrated once daily for 20 days. In the 20th day, the field potential recording was accomplished. Two-way ANOVA was used for data analysis followed by the Tukey test for post hoc analysis. Results were considered significant at P < 0.05. Results: This study shows the exposure to morphine declined the power of Delta and Beta bands (p<0.05 and Vit C solely enhance power of Theta and Beta (p<0.05, p<0.001 in VTA nuclei. Furthermore, Vit C could alter power of some bands which were affected by morphine. Therefore it seems that Vit C has an increasing effects on them (p<0.05. Conclusion: Although the effect of Vit C on power of the VTA bands is not well known, but it is supposed that this phenomenon can be related to alteration in activity of dopaminergic neuron in the brain.

  4. Action Potential Classification Based on PCA and Improved K-means Algorithm%基于PCA和改进K均值算法的动作电位分类

    Institute of Scientific and Technical Information of China (English)

    师黎; 杨振兴; 王治忠; 王岩

    2011-01-01

    微电极阵列记录的神经元信号往往是电极临近区域数个神经元的动作电位信号以及大量背景噪声的混叠,研究神经系统的信息处理机制以及神经编码、解码机理需了解相关每个神经元的动作电位,因此需从记录信号中分离出每个神经元的动作电位.基于此,提出基于主元分析(PCA)和改进K均值相结合的动作电位分类方法.该方法采用PCA提取动作电位特征,使用改进K均值算法实现动作电位分类.实验结果表明,该方法降低了动作电位的特征维数以及K均值算法对初始分类重心的依赖,提高动作电位分类结果的正确率及稳定性.尤其是在处理低信噪比信号时,分类正确率仍能达到理想水平.%Neural signal recorded by the microelectrode array is often the mixture which is composed of action potentials of several neurons near the electrodes and the background noises. Researches on the nervous system information processing mechanism and neural coding and decoding mechanism need know every related neuron's action potential. Therefore, every neuron's action potential is essential to be separated from the recorded signal. This paper proposes a method based on Principal Component Analysis(PCA) combined with improved K-means for action potential classification. The action potentials' features are extracted by PCA, the action potential classification is implemented by the improved K-means algorithm. Experimental results show that the method brings down action potential's feature dimensions and dependence of the initial classification center for the K-means algorithm, and increases the accuracy and stability of the classification results. Particularly, when processing the low Signal to Noise Ratio(SNR) signals, it can also achieve an expected purpose.

  5. In vitro antioxidant activity and potential inhibitory action againstα-glucosidase of polysaccharides from fruit peel of tea (Camellia sinensis L.)

    Institute of Scientific and Technical Information of China (English)

    Yue-fei WANG; Jie WANG; Jing WU; Ping XU; Yi-qi WANG; Jun-jie GAO; Danielle HOCHSTETTER

    2014-01-01

    本文题目:茶果皮多糖理化性质、体外抗氧化活性及对α-葡萄糖苷酶的抑制作用In vitro antioxidant activity and potential inhibitory action againstα-glucosidase of polysac-charides from fruit peel of tea (Camellia sinensis L.)研究目的:利用响应面优化茶果皮多糖(TFPP)提取条件,用乙醇分级分段得到4个多糖组分(TFPP-0、TFPP-20、TFPP-40和TFPP-60),并研究其理化性质、抗氧化活性和对α-葡萄糖苷酶抑制作用,为综合高效利用茶果皮多糖资源提供理论基础。创新要点:1.首次将茶果皮作为一种潜在生物资源研究;2.首次研究茶果皮多糖这一功能成分;3.将工艺优化、理化性质和生物活性结合研究。研究方法:三因素三水平响应面设计(见表1),傅里叶转换红外光谱法分析茶果皮粗多糖的功能团结构(见图3),高效液相色谱法检测单糖组分(见表2),2,2'-氨基-二(3-乙基-苯并噻唑啉-6-磺酸)二铵盐(ABTS)自由基清除法(见图4a)和铁离子还原能力法(FRAP)(见图4b)分析茶果皮多糖抗氧化活性。重要结论:1.茶果皮多糖是一种水溶性的酸性杂多糖蛋白复合物;2.乙醇分级是一种有效多糖分离手段;3.茶果皮多糖具有出色的生物活性;4.茶果皮资源可以作为一种可再生生物资源进行深度的开发。%The conditions for extracting polysaccharides from tea (Camel ia sinensis L.) fruit peel (TFPPs) were studied. Three parameters (temperature, time, and liquid/solid ratio) affecting the extraction of TFPP were optimized using response surface methodology (RSM). Under the optimized conditions, the yield of TFPP was predicted to be 4.98%. The physicochemical properties, in vitro antioxidant activities, and inhibitory effects onα-glucosidase of frac-tionated TFPPs (TFPP-0, TFPP-20, TFPP-40, and TFPP-60) were investigated. We found that the TFPPs were all acid protein

  6. 利拉鲁肽治疗糖尿病的作用特点及安全性%Action Characteristics and Safety of Liraglutide in Treating Diabetes

    Institute of Scientific and Technical Information of China (English)

    高茜倩; 陈玉文; 刘萍

    2015-01-01

    Objective To understand and introduce the new drug liraglutide, an acylated glucagon-like peptide-1 ( GLP-1 ) analogues, for treating diabetes mellitus. Methods All the published liraglutide-related articles were retrieved from the medicine literature databases from 2000 to June 2012 and analyzed comprehensively, including the action characteristics and safety of liraglutide. Results Liraglutide plays an important role in activating GLP-1 receptors, which presenting the glucose-dependence, stimulating the insulin se-cretion and simultaneously inhibiting the glucagon secretion. Liraglutide can rapidly and efficiently reduce the blood glucose and glycated hemoglobin levels for the treatment of NIDDM in clinical application. But 7% -40% of users had the gastrointestinal adverse reactions, 8. 6% of users appeared antibodies in vivo, the pancreatitis incidence was 0. 2%, in which acute pancreatitis accounted for 0. 034%, the ratio of inducing thyroid adverse reaction was higher than that in the placebo group by 0. 35%, 4% of users appeared slight increase of serum bilirubin, in addition, 2% of patients appeared rash and erythema at injection site. It is not recommended to use liraglutide during pregnancy and lactation due to this injection inducing mouse and rabbit fetal skeletal deformation. Although the probability of the drug-drug interactions related liraglutide combined with CYP450 and plasma protein binding is lower, but because of delay of gastric emptying, liraglutide may affect the absorption of other simultaneously administrated drugs. Conclusion Liraglutide is an exceptional hy-poglycemic drug for protecting pancreatic island cells, which provides a new choice for the treatment of type 2 diabetes mellitus and comes under the attention of medical field. Its clinical use could induce the safety problems of thyroid cancer and pancreatitis risks, which also causes concern. Liraglutide should be contraindicated for the patients with medullary thyroid carcinoma and

  7. Chemical characteristics and methane potentials of source-separated and pre-treated organic municipal solid waste

    DEFF Research Database (Denmark)

    Hansen, Trine Lund; Svärd, Å; Angelidaki, Irini;

    2003-01-01

    A research project has investigated the biogas potential of pre-screened source-separated organic waste. Wastes from five Danish cities have been pre-treated by three methods: screw press; disc screen; and shredder and magnet. This paper outlines the sampling procedure used, the chemical...... composition of the wastes and the estimated methane potentials....

  8. Cross-cultural validation of the child abuse potential inventory in Belgium (Flanders) : Relations with demographic characteristics and parenting problems

    NARCIS (Netherlands)

    Grietens, Hans; De Haene, Lucia; Uyttebroek, Karolien

    2007-01-01

    This study examined the reliability and the validity of the Dutch CAP Inventory, a screening instrument that measures parents' potential for child physical abuse (Milner, The Child Abuse Potential Inventory: Manual (2nd ed.), Psytec, Webster, NC, 1986). The CAP Inventory and measures on parenting st

  9. Site of cochlear stimulation and its effect on electrically evoked compound action potentials using the MED-EL standard electrode array

    Directory of Open Access Journals (Sweden)

    Helbig Silke

    2009-12-01

    Full Text Available Abstract Background The standard electrode array for the MED-EL MAESTRO cochlear implant system is 31 mm in length which allows an insertion angle of approximately 720°. When fully inserted, this long electrode array is capable of stimulating the most apical region of the cochlea. No investigation has explored Electrically Evoked Compound Action Potential (ECAP recordings in this region with a large number of subjects using a commercially available cochlear implant system. The aim of this study is to determine if certain properties of ECAP recordings vary, depending on the stimulation site in the cochlea. Methods Recordings of auditory nerve responses were conducted in 67 subjects to demonstrate the feasibility of ECAP recordings using the Auditory Nerve Response Telemetry (ART™ feature of the MED-EL MAESTRO system software. These recordings were then analyzed based on the site of cochlear stimulation defined as basal, middle and apical to determine if the amplitude, threshold and slope of the amplitude growth function and the refractory time differs depending on the region of stimulation. Results Findings show significant differences in the ECAP recordings depending on the stimulation site. Comparing the apical with the basal region, on average higher amplitudes, lower thresholds and steeper slopes of the amplitude growth function have been observed. The refractory time shows an overall dependence on cochlear region; however post-hoc tests showed no significant effect between individual regions. Conclusions Obtaining ECAP recordings is also possible in the most apical region of the cochlea. However, differences can be observed depending on the region of the cochlea stimulated. Specifically, significant higher ECAP amplitude, lower thresholds and steeper amplitude growth function slopes have been observed in the apical region. These differences could be explained by the location of the stimulating electrode with respect to the neural tissue

  10. Forest Gardens as an 'intermediate' land-use system in the nature-culture continuum: Characteristics and future potential

    NARCIS (Netherlands)

    Wiersum, K.F.

    2004-01-01

    Forest gardens are reconstructed natural forests, in which wild and cultivated plants coexist, such that the structural characteristics and ecological processes of natural forests are preserved, although the species composition has been adapted to suit human needs. These agroforests include a range

  11. IN-VITRO GROWTH CHARACTERISTICS OF COMMERCIAL PROBIOTIC STRAINS AND THEIR POTENTIAL FOR INHIBITION OF CLOSTRIDIUM DIFFICILE AND CLOSTRDIDUM PERFRINGENS

    DEFF Research Database (Denmark)

    Schoster, Angelika; Kokotovic, Branko; Permin, Anders;

    . To study growth characteristics of 17 commercial probiotic strains (Lactobacilli n=16, Bifidobacteria n=1) MRS broth was adjusted to pH 2 or 4 or supplemented with 0.15% or 0.3% bile. Growth was measured at 0 and 24h and compared spectrophotometrically to control growth in standard MRS broth. Growth under...

  12. Inhibition of C. difficile and C. perfringens by commercial and potential probiotic strains and their in-vitro growth characteristics

    DEFF Research Database (Denmark)

    Schoster, A.; Kokotovic, Branko; Permin, A.;

    2012-01-01

    strains (Lactobacilli n=16, Bifidobacteria n=1) on growth of clostridia spp was assessed in an agar well diffusion assay and broth co-culture experiment, using supernatant harvested at different growth phases and with and without pH adjustment. To study growth characteristics MRS broth was adjusted to pH2...

  13. In-vitro growth characteristics of commercial probiotic strains and their potential for inhibition of Clostridium difficile and Clostridium perfringens

    DEFF Research Database (Denmark)

    Schoster, A.; Kokotovic, Branko; Permin, A.;

    2012-01-01

    . To study growth characteristics of 17 commercial probiotic strains (Lactobacilli n=16, Bifidobacteria n=1) MRS broth was adjusted to pH 2 or 4 or supplemented with 0.15% or 0.3% bile. Growth was measured at 0 and 24h and compared spectrophotometrically to control growth in standard MRS broth. Growth under...

  14. Multi-centre European study of breakthrough cancer pain: pain characteristics and patient perceptions of current and potential management strategies

    DEFF Research Database (Denmark)

    Davies, Andrew; Zeppetella, Giovambattista; Andersen, Steen;

    2011-01-01

    This study involved 320 cancer patients from four Northern European countries. Patients with breakthrough pain were questioned about the characteristics of their pain, the current management of their pain, and the acceptability/utility of alternative routes of administration. The median number of...

  15. Action physics

    Science.gov (United States)

    McGinness, Lachlan P.; Savage, C. M.

    2016-09-01

    More than a decade ago, Edwin Taylor issued a "call to action" that presented the case for basing introductory university mechanics teaching around the principle of stationary action [E. F. Taylor, Am. J. Phys. 71, 423-425 (2003)]. We report on our response to that call in the form of an investigation of the teaching and learning of the stationary action formulation of physics in a first-year university course. Our action physics instruction proceeded from the many-paths approach to quantum physics to ray optics, classical mechanics, and relativity. Despite the challenges presented by action physics, students reported it to be accessible, interesting, motivational, and valuable.

  16. Complementary Actions

    Directory of Open Access Journals (Sweden)

    Luisa eSartori

    2015-05-01

    Full Text Available Complementary colors are color pairs which, when combined in the right proportions, produce white or black. Complementary actions refer here to forms of social interaction wherein individuals adapt their joint actions according to a common aim. Notably, complementary actions are incongruent actions. But being incongruent is not sufficient to be complementary (i.e., to complete the action of another person. Successful complementary interactions are founded on the abilities: (i to simulate another person’s movements, (ii to predict another person’s future action/s, (iii to produce an appropriate incongruent response which differ, while interacting, with observed ones, and (iv to complete the social interaction by integrating the predicted effects of one’s own action with those of another person. This definition clearly alludes to the functional importance of complementary actions in the perception–action cycle and prompts us to scrutinize what is taking place behind the scenes. Preliminary data on this topic have been provided by recent cutting-edge studies utilizing different research methods. This mini-review aims to provide an up-to-date overview of the processes and the specific activations underlying complementary actions.

  17. Repetition-induced plasticity of motor representations of action sounds.

    Science.gov (United States)

    Bourquin, Nathalie M-P; Simonin, Alexandre; Clarke, Stephanie

    2013-01-01

    Action-related sounds are known to increase the excitability of motoneurones within the primary motor cortex (M1), but the role of this auditory input remains unclear. We investigated repetition priming-induced plasticity, which is characteristic of semantic representations, in M1 by applying transcranial magnetic stimulation pulses to the hand area. Motor evoked potentials (MEPs) were larger while subjects were listening to sounds related versus unrelated to manual actions. Repeated exposure to the same manual-action-related sound yielded a significant decrease in MEPs when right, hand area was stimulated; no repetition effect was observed for manual-action-unrelated sounds. The shared repetition priming characteristics suggest that auditory input to the right primary motor cortex is part of auditory semantic representations. PMID:23064984

  18. Investigation of Current-Voltage Characteristics of Ni/GaN Schottky Barrier Diodes for Potential HEMT Applications

    Directory of Open Access Journals (Sweden)

    Ashish Kumar

    2011-01-01

    Full Text Available In the present work, the I-V characteristics of Ni/GaN Schottky diodes have been studied. The Schottky diodes, having different sizes using Ni/Au and ohmic contacts using Ti/Al/Ni/Au were made on n-GaN. The GaN was epitaxially grown on c-plane sapphire by metal organic chemical vapor deposition (MOCVD technique and had a thickness of about 3.7 µm. The calculated ideality factor and barrier height from current-voltage (I-V characteristics (at 300 K for two GaN Schottky diodes were close to ~1.3 and ~ 0.8 eV respectively. A high reverse leakage current in the order of 10 – 4A/cm2 (at – 1 V was observed in both diodes. A careful analysis of forward bias I-V characteristics showed very high series resistance and calculation for ideality factor indicated presence of other current transport mechanism apart from thermionic model at room temperature.

  19. The defining characteristics of Web 2.0 and their potential influence in the online vaccination debate.

    Science.gov (United States)

    Witteman, Holly O; Zikmund-Fisher, Brian J

    2012-05-28

    The emergence of Web 2.0 has led to more and more Web-based resources demonstrating three defining characteristics: user participation, openness and network effects. This paper discusses these characteristics in the context of the online vaccination debate, explores how they structurally alter the way people might interact with vaccination information online, and describes ways in which such characteristics support particular tendencies in human decision making processes. Specifically, user participation supports the influence of narratives and personal accounts, openness shapes expectations for greater levels of detail and movement toward models of informed decision making, and network effects demonstrate the social nature of decision making, the influence of like-minded others and thus, the pitfalls of polarization in the online vaccination debate. Web 2.0 means that concerns about vaccination information online must expand beyond simply the possibility that people might access information of varying quality to incorporate a more comprehensive understanding of how people use current Web functionality, how such usage influences expectations about information sources and decision making processes, and the implications for communication strategies about vaccination.

  20. Effects of sera obtained from electrically charged human body on action potential of giant axon of squid and its relationship to the therapy of the atomic bomb sequela, (2)

    International Nuclear Information System (INIS)

    The giant axon of squid was perfused for 20 min with sea water and four kinds of mixture of sera and sea water (1:2), and spike potential of the axon was compared by using a computer. Perfusates used were sea water, sera obtained before electric charge to the human body (pre-sera), sera obtained from the human body electrically charged with -300 volt (negative sera), and sera obtained from the human body electrically charged with +300 volt (positive sera). Negative sera increased action potential of the axon, and positive sera decreased action potential of the axon. These results revealed that negative sera have a greater deal of e-, and positive sera have less quantity of e- than pre-sera, suggesting the involvement of e- in the action potential of the axon. Microtubules in the inner part of the axonal membrane and cell membrane seem to be most greatly related to e-; however, changes in the other axons, cell membrane and protoplasm should also be taken into account. These experimental results seem to be of great value, particularly providing useful information on the treatment for late effects (cell damage) of atomic bombing or burn. (Namekawa, K.)

  1. What to do when your CTQs (critical-to-quality characteristics) turn into WTFs (what-the-flig): a guide to root cause analysis and corrective action

    Science.gov (United States)

    Coleman, Lance B.

    2015-09-01

    So what do you do when something has gone unexpectedly wrong with the process that you are monitoring or when your current state falls for short of desired state? Often the response is to call together the team, "huddle up", brainstorm and come up with a solution pulled from "tribal knowledge". There may also be some trial-and-error or one-factor-at-a-time experimentation to confirm conclusions. Truth be told that is all that is needed probably 80% of the time in many environments. What do you do however, when the event under study is complex and falls into that 20% bucket. In times like this taking the aforementioned unstructured approach would likely fail to discover the information needed or worse yet, may lead the team to draw a wrong conclusion. ? Now would be the time that a structured root cause analysis and corrective action process should be deployed. This paper will discuss three root cause analysis tools that can be used in situations of varying complexity. It will also discuss the corrective action process and pitfalls to avoid.

  2. Differential expression of hERG1 channel isoforms reproduces properties of native I(Kr) and modulates cardiac action potential characteristics

    DEFF Research Database (Denmark)

    Larsen, Anders Peter; Olesen, Søren-Peter

    2010-01-01

    The repolarizing cardiac rapid delayed rectifier current, I(Kr), is composed of ERG1 channels. It has been suggested that two isoforms of the ERG1 protein, ERG1a and ERG1b, both contribute to I(Kr). Marked heterogeneity in the kinetic properties of native I(Kr) has been described. We hypothesized...

  3. The changes in female physical and childbearing characteristics in china and potential association with risk of breast cancer

    Directory of Open Access Journals (Sweden)

    Zhang Qiang

    2012-05-01

    Full Text Available Abstract Background There has been a sharp increase in the incidence of breast cancer in China in recent years. A number of female physical characteristics, such as age at menarche, menopause, first birth and the duration of breastfeeding, have been linked to breast cancer, yet data on these factors in Chinese women is largely missing both for aggregate and age-specific data. Thus, the objective of this study was to explore changes in female menstrual and childbearing characteristics as a possible explanation for increasing rates of breast cancer in this country. Method From July to September 2008, a population based cross-sectional breast cancer survey covering 124,758 females from 4 provinces or cities in Eastern China was carried out, using multi-stage and cluster methods. In-person interviews based on a self-designed structured questionnaire were performed, in which female physiological and reproductive factors, such as age at menarche and menopause, menstrual cycle history, childbearing history, breastfeeding methods, abortions or miscarriage, were included. For every 10-year age category, the subjects were divided, and across those age groups, all the above factors were compared respectively and changes in physical and childbearing characteristics were evaluated. ANOVA was used to compare the differences across the groups. Results A total of 122058 subjects were included in the final analysis. The mean age at menarche was 15.39 years, the mean number of full-term pregnancies was 1.58, the mean duration of breastfeeding was 22.68 months, the mean age at first birth was 23.75 years, the mean frequency of miscarriage was 0.36, and the mean age at menopause was 48.63 years. Significant differences across the several age groups were noted for the age at menarche, number of full-term pregnancies, accumulated duration of breastfeeding, age at first birth, number of miscarriages, and age at menopause. These data clearly showed a gradual

  4. Study of crotoxin mechanism of action to mammary carcinomas and evaluation of its potential as a radiopharmaceutical; Estudo do mecanismo de acao da crotoxina em tumores mamarios e avaliacao do seu potenctial radiofarmaceutico

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Marina Bicalho

    2010-07-01

    Crotoxin, the main component of Crotalus durissus terrificus snake venom, has been studied since 1938. It is a natural polypeptidic complex with pharmacological potential because of its antitumoral properties which has attracted great interest for diagnosis and therapy of oncological diseases. However, Crotoxin mechanism of action and sites of specific interaction on tumor cells are still misunderstood. Breast cancer is the second most frequent type in the world and the most common cancer in women. About 30 to 60% of mammary tumors overexpress epidermal growth factor receptor (EGFR), a transmembrane protein related to cell proliferation. Since literature has reported that Crotoxin antitumoral effect is more potent on cells with EGFR overexpression the objectives of this work were to evaluate Crotoxin cytotoxic effects on mammary tumor cells human breast carcinoma (MCF-7) and Ehrlich tumor cells (murine ascitics carcinoma), and to investigate the specific molecular interaction of Crotoxin on Ehrlich tumor cells. Initially, Crotoxin was radiolabelled with iodine-125 ({sup 125}I-Crotoxin) and iodine-131 ({sup 131}I-Crotoxin). Saturation and competition assay were carried out to characterize Crotoxin in vitro interaction; Crotoxin biodistribution studies and singlephoton emission computed tomography (SPECT) of mice bearing Ehrlich tumor have been evaluated to describe in vivo interaction. Our results showed that Crotoxin presented cytotoxic effect against Ehrlich with DL{sub 50} in vitro (concentration of compound which is lethal for 50% of cells) of about one micromolar, but did not present significant effect against MCF-7. Morphological alterations characteristic of apoptosis suggests programmed cell death. {sup 125}I-Crotoxin interaction with Ehrlich tumor cells was saturable with approximately 70% specificity, and presented K{sub d}=24.98 nmol/L and B{sub max}=16,570 sites/cell for low affinity binding sites and K{sub d}=0.06 nmol/L and B{sub max}=210 sites

  5. Toward Understanding the Potential of Games for Learning: Learning Theory, Game Design Characteristics, and Situating Video Games in Classrooms

    Science.gov (United States)

    Turkay, Selen; Hoffman, Daniel; Kinzer, Charles K.; Chantes, Pantiphar; Vicari, Christopher

    2014-01-01

    Researchers have argued that an effort should be made to raise teachers' and parents' awareness of the potentially positive educational benefits of playing video games (e.g., see Baek, 2008). One part of this effort should be to increase understanding of how video games can be situated within teachers' existing goals and knowledge…

  6. Energy consumption practices of rural households in north China: Basic characteristics and potential for low carbon development

    NARCIS (Netherlands)

    Liu Wenling, Wenling; Spaargaren, G.; Heerink, N.; Mol, A.P.J.; Wang, C.

    2013-01-01

    Reducing the climate impact of rural household energy consumption in China is complicated since it is bound up with deeply routinized daily practices and dependent from existing infrastructural systems of energy supply. To assess the potential for low carbon development we first estimate the overall

  7. Beyond the adoption/ non-adoption dichotomy: the impact of innovation characteristics on potential adopters' transition through adoption process stages

    NARCIS (Netherlands)

    Agarwal, M.K.; Frambach, R.T.

    2002-01-01

    Research on innovation adoption has suffered from a bias towards understanding the factors that affect the dichotomous adoption/non-adoption decision.Much less attention is devoted to the question why potential adopters fail to progress to the adoption stage from earlier stages in the decision makin

  8. Energy material transport, now through 2000, system characteristics and potential problems. Task 2 final report: coal transportation.

    Energy Technology Data Exchange (ETDEWEB)

    DeSteese, J.G.; Bamberger, J.A.; Franklin, A.L.; Hendrickson, P.L.; Lippek, H.E.; Loscutoff, W.V.; Wilson, C.L.

    1978-06-01

    This report contains a summary characterization of the existing domestic coal transportation system and an assessment of some potential problems which may impact coal transportation in the United States during the balance of the century. A primary purpose of this task is to provide information and perspective that contributes to the evaluation of research and development needs and priorities in future programs. Specific concerns are identified which warrant additional programmatic effort to fill apparent gaps in the coverage of other relevant programs. Recommendations are made for new programs to address these concerns according to their apparent importance under conditions known or anticipated in early 1978. These recommendations are intended to encourage new research initiatives by the coal transportation industry, the Department of Energy (DOE) and other cognizant agencies. Concerns were identified by the analysis of problem issues associated with currently-projected growth scenarios for domestic coal consumption. The assessment of potential problem effects on the adequacy of future coal transportation assumes domestic coal production levels of approximately one billion tons in 1985 and two billion tons by the year 2000. The relative priorities of potential problems were judged on the basis of their overall impact on the system and the immediacy of this potential impact.

  9. Learning about goals: development of action perception and action control

    OpenAIRE

    Verschoor, Stephan Alexander

    2014-01-01

    By using innovative paradigms, the present thesis provides convincing evidence that action-effect learning, and sensorimotor processes in general play a crucial role in the development of action- perception and production in infancy. This finding was further generalized to sequential action. Furthermore the thesis suggests that means-selection-, ends-selection information, and action-effect knowledge together feed into a unitary concept of goal. Both these findings have the potential to gener...

  10. A data warehouse of muscle characteristics and beef quality in France and a demonstration of potential applications

    Directory of Open Access Journals (Sweden)

    Sghaier Chriki

    2013-05-01

    Full Text Available The BIF-Beef (Beef Integrated and Functional Biology database contains animal, carcass, muscle and meat data (331,745 entries collected from 43 experiments over the last 20 years and a great number of variables (621 characterising muscles (fat and collagen contents, cross-section and types of fibres, metabolic activity, making it a relevant tool to relate muscle characteristics to beef quality. Wide variation was observed in all described traits according to muscle type, sex and breed. The BIF-Beef database was mainly composed of data from young bulls of late-maturing beef breeds, which is why live weight and carcass weights of the animals were greater, and beef was leaner and lighter than results from other existing databases. Average cross-sectional area of fibres was greater in Semitendinosus than in Longissimus thoracis muscle and, for Longissimus, greater in steers than in young bulls. Intramuscular fat content was in descending order: Charolais > Limousin > Blond d’Aquitaine and females > steers > young bulls. Semitendinosus muscle was less oxidative and contained more collagen than Longissimus muscle. Collagen content in Longissimus was higher in Charolais than in Blond d’Aquitaine and Limousin young bulls. Within the Charolais breed, collagen content in Longissimus was higher in young bulls and steers than in females. Longissimus samples from young bulls were less tender than from females. Based on the above results, this database is a prerequisite for meta-analysis of relationships between muscle characteristics and beef quality in the European context.

  11. The characteristics of decision making, potential to take risks, and personality of college students with Internet addiction.

    Science.gov (United States)

    Ko, Chih-Hung; Hsiao, Sigmund; Liu, Gin-Chung; Yen, Ju-Yu; Yang, Ming-Jen; Yen, Cheng-Fang

    2010-01-30

    This study aimed to identify risk factors involved in Internet addiction. A total of 216 college students (132 males and 84 females) were given the following: (a) the diagnostic interview for Internet addiction, (b) the Iowa gambling test for decision-making deficits, (c) the Balloon Analog Risk Test (BART) to assess risk-taking tendencies, and (d) the Tridimensional Personality Questionnaire (TPQ) for personality characteristics. The results revealed the following: (a) 49% of males and 17% of females were addicted, (b) the addicted students tended to select more advantageous cards in the last 40 cards of the Iowa test, indicating better decision making, (c) no difference was found for the BART, indicating that addicted subjects were not more likely to engage in risk-taking behaviors and (d) TPQ scores showed lower reward dependence (RD) and higher novelty seeking (NS) for the addicts. Their higher performance on the Iowa gambling test differentiates the Internet addiction group from the substance use and pathologic gambling groups that have been shown to be deficient in decision making on the Iowa test. Thus, students that fit these characteristics should be closely monitored to prevent Internet addiction. PMID:19962767

  12. 基于ADAMS的助力型外骨骼特征动作驱动液压缸运动学研究%Kinematics research of exoskeleton characteristic action activated hydraulic cylinders based on ADAMS

    Institute of Scientific and Technical Information of China (English)

    李贤坤; 刘放; 迟振华; 赵兴忠

    2014-01-01

    以助力型外骨骼为研究对象,以建立助力型外骨骼运动学模型以及分析外骨骼运动学特性为研究目标,以运动生物力学为基础,选择单膝下跪-起立动作为特征动作,采用多层次光学捕捉系统采集人体运动数据,采用多波峰(波谷)最小二乘法进行数据拟合,得到人体运动时特征角度的数学模型。助力型外骨骼在完成动作时需要与人体高度偕行,因此将特征角度的数学模型运用到助力型外骨骼中,建立外骨骼三维模型,在ADAMS软件中完成外骨骼特征动作仿真,以此来分析外骨骼运动学特性。%Choose help exoskeleton for the study in order to establish the modeling of the assist -type exoskeleton and analytical ki-nematics characteristic of exoskeleton .Based on sports biomechanics ,select one knee-stand up action for characterized action .Use multi-level optical capture system to capture human motion data , and multi-peak ( trough ) method of least squares to fit data . Therefor get the mathematical model of the human motion characteristic angle .Help exoskeleton complete the characteristic action with body accompanying ,then the mathematical model of characterized angle must be used to help exoskeleton .Establish three-di-mensional model of the help exoskeleton ,and simulation the characterized action of help exoskeleton in ADAMS to analyze the ex-oskeleton kinematics .

  13. 牛磺酸对豚鼠乳头状肌慢反应动作电位的影响%Effects of taurine on slow action potentials in papillary muscles of guinea pig

    Institute of Scientific and Technical Information of China (English)

    李萍; 康毅; 王国祥

    1995-01-01

    目的:研究牛磺酸对豚鼠乳头状肌慢反应动作电位的影响.方法:高钾(24 mmol·L-1)或河豚毒素(40μmol·L-1)诱发慢反应动作电位.哇巴因诱发振荡后电位.结果:牛磺酸(20mmol·L-1)减少Vmax,延长APD50并拮抗氯化钙(3 mmol·L-1)增加APA和Vmax及缩短APD的作用,增加哇巴因诱发OAP所需浓度并延长其发生时间.结论:牛磺酸有钙拮抗剂的性质%AIM: To examine the effects of taurine on the slow action potentials induced by KCl 24mmol·L-1 or tetrodotoxin 40 μmol·L-1 in guinea pig papillary muscles. METHODS:The transmembrane AP was recorded by a conventional glass microelectrode filled with to high K+-Tyrode's solution or perfused with Tyrode's solution containing tetrodotoxin.Ouabain was added in order to induce oscillatory afterpotentials. RESULTS: Taurine 20locity of slow action potential and prolonged the action potential duration at 50 % of repolarization. The amplitude of slow action potential and the maximal upstroke velocity both nized by taurine. Taurine increased the concentration of ouabain for oscillatory afterpotential and prolonged the onset time of oscillatory afterpotential. CONCLUSION: Taurine possesses a calcium antagonistic property.

  14. Induced Rigid String Action From Fermions

    CERN Document Server

    Parthasarathy, R

    1999-01-01

    From the Dirac action on the world sheet, an effective action is obtained by integrating over the 4-dimensional fermion fields pulled back to the world sheet. This action consists of the Nambu-Goto area term with right dimensionful constant in front, extrinsic curvature action and the topological Euler characteristic term.

  15. [Performance characteristics of root zone moisture and water potential sensors for greenhouses in the conditions of extended space flight].

    Science.gov (United States)

    Podolskiy, I G; Strugov, O M; Bingham, G E

    2014-01-01

    The investigation was performed using greenhouse Lada in the Russian segment of the International space station (ISS RS) as part of space experiment Plants-2 during ISS missions 5 through to 22. A set of 6 point moisture sensors embedded in the root zone (turface particles of 1-2 mm in diam.) and 4 tensiometers inside root modules (RM) were used to monitor moisture content and water potential in the root zone. The purpose was to verify functionality and to test performance of the sensors in the spacefight environment. It was shown that with the average RZ moisture content of 80% the measurement error of the sensors do not exceed ± 1.5%. Dynamic analysis of the tensiometers measurements attests that error in water potential measurements does not exceed ± 111 Pa. PMID:26035998

  16. Energy material transport, now through 2000 system characteristics and potential problems. Task 4 progress report: natural gas transportation

    Energy Technology Data Exchange (ETDEWEB)

    DeSteese, J.G.; Geffen, C.A.

    1978-07-01

    A summary characterization is presented of the existing natural gas transportation system and an assessment of some potential problems which may impact natural gas transportation in the United States during the balance of the century. A primary purpose of this task is to provide information and perspective that contributes to the evaluation of research needs and priorities in future programs. Safety and environmental issues that should concern the gas industry, the Department of Energy (DOE) and other cognizant government agencies are emphasized. Specific potential problems are identified which warrant additional programmatic effort because they do not appear to be receiving adequate attention. New programs are recommended to address these concerns according to their apparent importance, under conditions known or anticipated in early 1978. Other safety and environmental concerns in natural gas transportation are also reviewed, and judged to be adequately addressed in ongoing programs. No additional effort appears to be needed in these areas at present.

  17. Molecular Characteristic, Protein Distribution and Potential Regulation of HSP90AA1 in the Anadromous Fish Coilia nasus

    OpenAIRE

    Di-An Fang; Jin-Rong Duan; Yan-Feng Zhou; Min-Ying Zhang; Dong-Po Xu; Kai Liu; Pao Xu

    2016-01-01

    Heat shock proteins play essential roles in basic cellular events. Spawning migration is a complex process, with significant structural and biochemical changes taking place in the adult gonad. To date, the molecular mechanisms underlying migration reproductive biology remain undetermined. In this regard, a full length HSP90AA1 comprising 2608 nucleotides from the anadromous fish Coilia nasus was characterized, encoding 742 amino acid (aa) residues with potential phosphorylation sites. HSP90AA...

  18. Enforcement actions: Significant actions resolved

    International Nuclear Information System (INIS)

    This compilation summarizes significant enforcement actions that have been resolved during one quarterly period (October - December 1993) and includes copies of letters, Notices, and Orders sent by the Nuclear Regulatory Commission to licensees with respect to these enforcement actions. It is anticipated that the information in this publication will be widely disseminated to managers and employees engaged in activities licensed by the NRC, so that actions can be taken to improve safety by avoiding future violations similar to those described in this publication

  19. Enforcement actions: Significant actions resolved

    International Nuclear Information System (INIS)

    This compilation summarizes significant enforcement actions that have been resolved during one quarterly period (July - September 1992) and includes copies of letters, Notices, and Orders sent by the Nuclear Regulatory Commission to licensees with respect to these enforcement actions. It is anticipated that the information in this publication will be widely disseminated to managers and employees engaged in activities licensed by the NRC, so that actions can be taken to improve safety by avoiding future violations similar to those described in this publication

  20. Enforcement actions: Significant actions resolved

    International Nuclear Information System (INIS)

    This compilation summarizes significant enforcement actions that have been resolved during one quarterly period (January--March 1989) and includes copies of letters, Notices, and Orders sent by the Nuclear Regulatory Commission to licensees with respect to these enforcement actions. Also included are a number of enforcement actions that had been previously resolved but not published in this NUREG. It is anticipated that the information in this publication will be widely disseminated to managers and employees engaged in activities licensed by the NRC, so that actions can be taken to improve safety by avoiding future violations similar to those described in this publication