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Search Results: 1 - 10 of 178 matches for " Geza Gemes "
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Painful nerve injury increases plasma membrane Ca2+-ATPase activity in axotomized sensory neurons
Geza Gemes, Katherine D Oyster, Bin Pan, Hsiang-En Wu, Madhavi LY Bangaru, Qingbo Tang, Quinn H Hogan
Molecular Pain , 2012, DOI: 10.1186/1744-8069-8-46
Abstract: PMCA function was isolated in dissociated sensory neurons by blocking intracellular Ca2+ sequestration with thapsigargin, and cytoplasmic Ca2+ concentration was recorded with Fura-2 fluorometry. Compared to control neurons, the rate at which depolarization-induced Ca2+ transients resolved was increased in axotomized neurons after spinal nerve ligation, indicating accelerated PMCA function. Electrophysiological recordings showed that blockade of PMCA by vanadate prolonged the action potential afterhyperpolarization, and also decreased the rate at which neurons could fire repetitively.We found that PMCA function is elevated in axotomized sensory neurons, which contributes to neuronal hyperexcitability. Accelerated PMCA function in the primary sensory neuron may contribute to the generation of neuropathic pain, and thus its modulation could provide a new pathway for peripheral treatment of post-traumatic neuropathic pain.
KATP channel subunits in rat dorsal root ganglia: alterations by painful axotomy
Vasiliki Zoga, Takashi Kawano, Mei-Ying Liang, Martin Bienengraeber, Dorothee Weihrauch, Bruce McCallum, Geza Gemes, Quinn Hogan, Constantine Sarantopoulos
Molecular Pain , 2010, DOI: 10.1186/1744-8069-6-6
Abstract: PCR demonstrated Kir6.1, Kir6.2, SUR1 and SUR2 transcripts in control DRG neurons. Protein expression for all but Kir6.1 was confirmed by Western blots and immunohistochemistry. Immunostaining of these subunits was identified by fluorescent and confocal microscopy in plasmalemmal and nuclear membranes, in the cytosol, along the peripheral fibers, and in satellite glial cells. Kir6.2 co-localized with SUR1 subunits. Kir6.2, SUR1, and SUR2 subunits were identified in neuronal subpopulations, categorized by positive or negative NF200 or CGRP staining. KATP current recorded in excised patches was blocked by glybenclamide, but preincubation with antibody against SUR1 abolished this blocking effect of glybenclamide, confirming that the antibody targets the SUR1 protein in the neuronal plasmalemmal membrane.In the myelinated nerve fibers we observed anti-SUR1 immunostaining in regularly spaced funneled-shaped structures. These structures were identified by electron microscopy as Schmidt-Lanterman incisures (SLI) formed by the Schwann cells. Immunostaining against SUR1 and Kir6.2 colocalized with anti-Caspr at paranodal sites.DRG excised from rats made hyperalgesic by spinal nerve ligation exhibited similar staining against Kir6.2, SUR1 or SUR2 as DRG from controls, but showed decreased prevalence of SUR1 immunofluorescent NF200 positive neurons. In DRG and dorsal roots proximal to axotomy SLI were smaller and showed decreased SUR1 immunofluorescence.We identified Kir6.2/SUR1 and Kir6.2/SUR2 KATP channels in rat DRG neuronal somata, peripheral nerve fibers, and glial satellite and Schwann cells, in both normal state and after painful nerve injury. This is the first report of KATP channels in paranodal sites adjacent to nodes of Ranvier and in the SLI of the Schwann cells. After painful axotomy KATP channels are downregulated in large, myelinated somata and also in SLI, which are also of smaller size compared to controls.Because KATP channels may have diverse functional role
Nitric oxide activates ATP-sensitive potassium channels in mammalian sensory neurons: action by direct S-nitrosylation
Takashi Kawano, Vasiliki Zoga, Masakazu Kimura, Mei-Ying Liang, Hsiang-En Wu, Geza Gemes, J Bruce McCallum, Wai-Meng Kwok, Quinn H Hogan, Constantine D Sarantopoulos
Molecular Pain , 2009, DOI: 10.1186/1744-8069-5-12
Abstract: Cell-attached and cell-free recordings of KATP currents in large DRG neurons from control rats (sham surgery, SS) revealed activation of KATP channels by NO exogenously released by the NO donor SNAP, through decreased sensitivity to [ATP]i.This NO-induced KATP channel activation was not altered in ganglia from animals that demonstrated sustained hyperalgesia-type response to nociceptive stimulation following spinal nerve ligation. However, baseline opening of KATP channels and their activation induced by metabolic inhibition was suppressed by axotomy. Failure to block the NO-mediated amplification of KATP currents with specific inhibitors of sGC and PKG indicated that the classical sGC/cGMP/PKG signaling pathway was not involved in the activation by SNAP. NO-induced activation of KATP channels remained intact in cell-free patches, was reversed by DTT, a thiol-reducing agent, and prevented by NEM, a thiol-alkylating agent. Other findings indicated that the mechanisms by which NO activates KATP channels involve direct S-nitrosylation of cysteine residues in the SUR1 subunit. Specifically, current through recombinant wild-type SUR1/Kir6.2 channels expressed in COS7 cells was activated by NO, but channels formed only from truncated isoform Kir6.2 subunits without SUR1 subunits were insensitive to NO. Further, mutagenesis of SUR1 indicated that NO-induced KATP channel activation involves interaction of NO with residues in the NBD1 of the SUR1 subunit.NO activates KATP channels in large DRG neurons via direct S-nitrosylation of cysteine residues in the SUR1 subunit. The capacity of NO to activate KATP channels via this mechanism remains intact even after spinal nerve ligation, thus providing opportunities for selective pharmacological enhancement of KATP current even after decrease of this current by painful-like nerve injury.Nitric oxide (NO) is a pivotal signaling molecule involved in many diverse developmental and physiological processes in the mammalian nervous system
Developing Trends of Railway Traffic Control
Geza Tarnai
Advances in Electrical and Electronic Engineering , 2004,
Abstract: The future of a railway operator is depending on the success of simultaneous improvement of service quality and cost effectiveness. In this paper we are going to investigate, how traffic control systems - by their developing trends - can contribute to the improvement of service quality and cost effectiveness. In course of this, the following topics will be highlighted: effect of the application of automation and telematics; issues of interoperability and the application of satellite based location.
The Blazhko Effect
Geza Kovacs
Physics , 2009, DOI: 10.1063/1.3246458
Abstract: Current status of (the lack of) understanding Blazhko effect is reviewed. We focus mostly on the various components of the failure of the models and touch upon the observational issues only at a degree needed for the theoretical background. Attention is to be paid to models based on radial mode resonances, since they seem to be not fully explored yet, especially if we consider possible non-standard effects (e.g., heavy element enhancement). To aid further modeling efforts, we stress the need for accurate time-series spectral line analysis to reveal any possible non-radial component(s) and thereby let to include (or exclude) non-radial modes in explaining the Blazhko phenomenon.
Critical behavior in reaction-diffusion systems exhibiting absorbing phase transition
Geza Odor
Physics , 2003, DOI: 10.1590/S0103-97332003000300003
Abstract: Phase transitions of reaction-diffusion systems with site occupation restriction and with particle creation that requires n>1 parents and where explicit diffusion of single particles (A) exists are reviewed. Arguments based on mean-field approximation and simulations are given which support novel kind of non-equilibrium criticality. These are in contradiction with the implications of a suggested phenomenological, multiplicative noise Langevin equation approach and with some of recent numerical analysis. Simulation results for the one and two dimensional binary spreading 2A -> 4A, 4A -> 2A model display a new type of mean-field criticality characterized by alpha=1/3 and beta=1/2 critical exponents suggested in cond-mat/0210615.
Estimation of the order parameter exponent of critical cellular automata using the enhanced coherent anomaly method.
Geza Odor
Physics , 1995, DOI: 10.1103/PhysRevE.51.6261
Abstract: The stochastic cellular automaton of Rule 18 defined by Wolfram [Rev. Mod. Phys. 55 601 (1983)] has been investigated by the enhanced coherent anomaly method. Reliable estimate was found for the $\beta$ critical exponent, based on moderate sized ($n \le 7$) clusters.
The phase transition of triplet reaction-diffusion models
Geza Odor
Physics , 2005, DOI: 10.1103/PhysRevE.73.047103
Abstract: The phase transitions classes of reaction-diffusion systems with multi-particle reactions is an open challenging problem. Large scale simulations are applied for the 3A -> 4A, 3A -> 2A and the 3A -> 4A, 3A->0 triplet reaction models with site occupation restriction in one dimension. Static and dynamic mean-field scaling is observed with signs of logarithmic corrections suggesting d_c=1 upper critical dimension for this family of models.
Self-organizing, two-temperature Ising model describing human segregation
Geza Odor
Physics , 2007, DOI: 10.1142/S0129183108012212
Abstract: A two-temperature Ising-Schelling model is introduced and studied for describing human segregation. The self-organized Ising model with Glauber kinetics simulated by M\"uller et al. exhibits a phase transition between segregated and mixed phases mimicking the change of tolerance (local temperature) of individuals. The effect of external noise is considered here as a second temperature added to the decision of individuals who consider change of accommodation. A numerical evidence is presented for a discontinuous phase transition of the magnetization.
Gravitational Microlensing and the Structure of the Inner Milky Way
Geza Gyuk
Physics , 1996,
Abstract: We analyze the first-year MACHO collaboration observations of microlensing towards the Galactic center using a new direct likelihood technique that is sensitive to the distribution of the events on the sky. We consider the full set of 41 events, and calculate the direct likelihood against a simply-parameterized Galactic model consisting of either a gaussian or exponential bar and a double exponential disk. Optical depth maps are calculated taking into account the contribution of both disk lenses and sources. We show that based on the presently available data, a slope in the optical depth has been clearly detected ($3\sigma$) in Galactic latitude and that there are indications of a small slope in Galactic longitude. We discuss limits that can be set on the mass, angle and axis ratio of the Galactic bulge. We show that based on microlensing considerations alone, $M_{Bulge}>1.5\times 10^{10}\Msol$ at the 90\% confidence level and that the bulge inclination angle is less than $30 \deg$ also at the 90\% confidence level. The mostly likely bar mass is $M_{Bulge}=3.5\times10^{10}\Msol$. Such a high mass would imply a low MACHO fraction for the halo. We consider disk parameters and show that there are two degeneracies between the effects of a disk and those of a bar on the optical depths. Finally, we discuss how to break these degeneracies and consider various strategies for future microlensing observations.
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