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https://www.readbyqxmd.com/read/28208271/cation-dependent-surface-charge-regulation-in-gated-nanofluidic-devices
#1
Marie Fuest, Kaushik K Rangharajan, Caitlin Boone, A T Conlisk, Shaurya Prakash
Surface charge governs nanoscale aqueous electrolyte transport, both in engineered analytical systems and in biological entities such as ion channels and ion pumps as a function of ion type and concentration. Embedded electrodes in a nanofluidic channel, isolated from the fluid in the channel by a dielectric layer, act as active, tunable gates to systematically modify local surface charge density at the interface between the nanochannel surface and the aqueous electrolyte solution, causing significant changes in measured nanochannel conductance...
February 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28206856/effect-of-photoperiod-on-permethrin-resistance-in-aedes-aegypti
#2
O Karina Villanueva, Gustavo Ponce, Beatriz Lopez, Selene M Gutierrez, Iram P Rodriguez, Guadalupe Reyes, Karla J Saavedra, William C Black, Julian Garcia, Barry Beaty, Lars Eisen, Adriana E Flores
Living organisms have been exposed to light-dark cycles that allowed them to adapt to different ecological niches. Circadian cycles affect hormone release, metabolism, and response to xenobiotic compounds. Current studies have shown that insect susceptibility to toxic agents depends on circadian cycles, mainly because the biochemical processes involved in detoxification and responses to oxidative stress are modulated by this process. The goal of this study was to determine the effect of photoperiod on resistance to permethrin in Aedes aegypti ...
December 2016: Journal of the American Mosquito Control Association
https://www.readbyqxmd.com/read/28205593/imaging-cardiac-scn5a-using-the-novel-f-18-radiotracer-radiocaine
#3
Jacob M Hooker, Martin G Strebl, Frederick A Schroeder, Hsiao-Ying Wey, Amrut V Ambardekar, Timothy A McKinsey, Matthias Schoenberger
The key function of the heart, a well-orchestrated series of contractions, is controlled by cardiac action potentials. These action potentials are initiated and propagated by a single isoform of voltage gated sodium channels - SCN5A. However, linking changes in SCN5A expression levels to human disease in vivo has not yet been possible. Radiocaine, an F-18 radiotracer for positron emission tomography (PET), is the first SCN5A imaging agent in the heart. Explants from healthy and failing human hearts were compared using radiocaine autoradiography to determine that the failing heart has ~30% lower SCN5A levels - the first evidence of changes in SCN5A expression in humans as a function of disease...
February 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28205548/the-complete-structure-of-an-activated-open-sodium-channel
#4
Altin Sula, Jennifer Booker, Leo C T Ng, Claire E Naylor, Paul G DeCaen, B A Wallace
Voltage-gated sodium channels (Navs) play essential roles in excitable tissues, with their activation and opening resulting in the initial phase of the action potential. The cycling of Navs through open, closed and inactivated states, and their closely choreographed relationships with the activities of other ion channels lead to exquisite control of intracellular ion concentrations in both prokaryotes and eukaryotes. Here we present the 2.45 Å resolution crystal structure of the complete NavMs prokaryotic sodium channel in a fully open conformation...
February 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/28202723/mapping-of-voltage-sensor-positions-in-resting-and-inactivated-mammalian-sodium-channels-by-lret
#5
Tomoya Kubota, Thomas Durek, Bobo Dang, Rocio K Finol-Urdaneta, David J Craik, Stephen B H Kent, Robert J French, Francisco Bezanilla, Ana M Correa
Voltage-gated sodium channels (Navs) play crucial roles in excitable cells. Although vertebrate Nav function has been extensively studied, the detailed structural basis for voltage-dependent gating mechanisms remain obscure. We have assessed the structural changes of the Nav voltage sensor domain using lanthanide-based resonance energy transfer (LRET) between the rat skeletal muscle voltage-gated sodium channel (Nav1.4) and fluorescently labeled Nav1.4-targeting toxins. We generated donor constructs with genetically encoded lanthanide-binding tags (LBTs) inserted at the extracellular end of the S4 segment of each domain (with a single LBT per construct)...
February 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28202629/improving-the-in-silico-assessment-of-proarrhythmia-risk-by-combining-herg-human-ether-%C3%A3-go-go-related-gene-channel-drug-binding-kinetics-and-multichannel-pharmacology
#6
Zhihua Li, Sara Dutta, Jiansong Sheng, Phu N Tran, Wendy Wu, Kelly Chang, Thembi Mdluli, David G Strauss, Thomas Colatsky
BACKGROUND: The current proarrhythmia safety testing paradigm, although highly efficient in preventing new torsadogenic drugs from entering the market, has important limitations that can restrict the development and use of valuable new therapeutics. The CiPA (Comprehensive in vitro Proarrhythmia Assay) proposes to overcome these limitations by evaluating drug effects on multiple cardiac ion channels in vitro and using these data in a predictive in silico model of the adult human ventricular myocyte...
February 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28202576/differential-effect-of-brief-electrical-stimulation-on-voltage-gated-potassium-channels
#7
Morven Alison Cameron, Amr Al Abed, Yossi Buskila, Socrates Dokos, Nigel H Lovell, John W Morley
Electrical stimulation of neuronal tissue is a promising strategy to treat a variety of neurological disorders. The mechanism of neuronal activation by external electrical stimulation is governed by voltage-gated ion channels. This stimulus, typically brief in nature, leads to membrane potential depolarization, which increases ion flow across the membrane by increasing the open probability of these voltage-gated channels. In spiking neurons, it is activation of voltage-gated sodium channels (NaV-channels) that leads to action potential generation...
February 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28202509/sodium-channel-subunit-scnn1b-suppresses-gastric-cancer-growth-and-metastasis-via-grp78-degradation
#8
Jun Yu, Qian Yun, Chi Chun Wong, Jiaying Xu, Huarong Chen, Yanquan Zhang, Wei Kang, Hua Wang, Li Zhang, Weilin Li, Eagle Sh Chu, Minnie Yy Go, Philip Wy Chiu, Enders Kw Ng, Francis Kl Chan, Joseph Jy Sung, Jianmin Si
There remains a paucity of functional biomarkers in gastric cancer. Here we report the identification of the sodium channel subunit SCNN1B as a candidate biomarker in gastric cancer (GC). SCNN1B mRNA expression was silenced commonly by promoter hypermethylation in GC cell lines and primary tumor tissues. Tissue microarray analysis revealed that high expression of SCNN1B was an independent prognostic factor for longer survival in GC patients, especially those with late-stage disease. Functional studies demonstrated that SCNN1B overexpression was sufficient to suppress multiple features of cancer cell pathophysiology in vitro and in vivo...
February 15, 2017: Cancer Research
https://www.readbyqxmd.com/read/28202327/synthesis-and-evaluation-of-anticonvulsant-properties-of-new-n-mannich-bases-derived-from-pyrrolidine-2-5-dione-and-its-3-methyl-3-isopropyl-and-3-benzhydryl-analogs
#9
Sabina Rybka, Jolanta Obniska, Anna Rapacz, Barbara Filipek, Paweł Żmudzki
The aim of this paper was to describe the synthesis of a library of 28 new 1,3-substituted pyrrolidine-2,5-dione as potential anticonvulsant agents. The anticonvulsant activity was evaluated using three acute models of seizures in mice (MES-maximal electroshock, scPTZ-subcutaneous pentylenetetrazole, and 6Hz-psychomotor seizure tests). The neurotoxicity was determined by rotarod test. The most promising compound was found to be N-[{morpholin-1-yl}-methyl]-3-benzhydryl-pyrrolidine-2,5-dione (15), as it was active in the MES (ED50=41...
February 4, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28195313/neuronal-sodium-channels-emerging-components-of-the-nano-machinery-of-cardiac-calcium-cycling
#10
Rengasayee Veeraraghavan, Sándor Györke, Przemysław B Radwański
Excitation-contraction coupling (ECC) is the bridge between cardiac electrical activation and mechanical contraction. It is driven by the influx of Ca(2+) across the sarcolemma triggering Ca(2+) release from the sarcoplasmic reticulum (SR) - a process termed Ca(2+) -induced Ca(2+) release (CICR) - followed by re-sequestration of Ca(2+) into the SR. The sodium calcium exchanger (NCX) inextricably couples the cycling of Ca(2+) and Na(+) in cardiac myocytes. Thus, influx of Na(+) via voltage-gated Na(+) channels (NaV ) has emerged as an important regulator of CICR both in health and in disease...
February 14, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28193882/neuronal-hyperexcitability-in-a-mouse-model-of-scn8a-epileptic-encephalopathy
#11
Luis F Lopez-Santiago, Yukun Yuan, Jacy L Wagnon, Jacob M Hull, Chad R Frasier, Heather A O'Malley, Miriam H Meisler, Lori L Isom
Patients with early infantile epileptic encephalopathy (EIEE) experience severe seizures and cognitive impairment and are at increased risk for sudden unexpected death in epilepsy (SUDEP). EIEE13 [Online Mendelian Inheritance in Man (OMIM) # 614558] is caused by de novo missense mutations in the voltage-gated sodium channel gene SCN8A Here, we investigated the neuronal phenotype of a mouse model expressing the gain-of-function SCN8A patient mutation, p.Asn1768Asp (Nav1.6-N1768D). Our results revealed regional and neuronal subtype specificity in the effects of the N1768D mutation...
February 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28193786/bile-acids-potentiate-proton-activated-currents-in-xenopus-laevis-oocytes-expressing-human-acid-sensing-ion-channel-asic1a
#12
Alexandr V Ilyaskin, Alexei Diakov, Christoph Korbmacher, Silke Haerteis
Acid-sensing ion channels (ASICs) are nonvoltage-gated sodium channels transiently activated by extracellular protons and belong to the epithelial sodium channel (ENaC)/Degenerin (DEG) family of ion channels. Bile acids have been shown to activate two members of this family, the bile acid-sensitive ion channel (BASIC) and ENaC. To investigate whether bile acids also modulate ASIC function, human ASIC1a was heterologously expressed in Xenopus laevis oocytes. Exposing oocytes to tauro-conjugated cholic (t-CA), deoxycholic (t-DCA), and chenodeoxycholic (t-CDCA) acid at pH 7...
February 2017: Physiological Reports
https://www.readbyqxmd.com/read/28192542/functional-diversity-of-secreted-cestode-kunitz-proteins-inhibition-of-serine-peptidases-and-blockade-of-cation-channels
#13
Martín Fló, Mariana Margenat, Leonardo Pellizza, Martín Graña, Rosario Durán, Adriana Báez, Emilio Salceda, Enrique Soto, Beatriz Alvarez, Cecilia Fernández
We previously reported a multigene family of monodomain Kunitz proteins from Echinococcus granulosus (EgKU-1-EgKU-8), and provided evidence that some EgKUs are secreted by larval worms to the host interface. In addition, functional studies and homology modeling suggested that, similar to monodomain Kunitz families present in animal venoms, the E. granulosus family could include peptidase inhibitors as well as channel blockers. Using enzyme kinetics and whole-cell patch-clamp, we now demonstrate that the EgKUs are indeed functionally diverse...
February 13, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28192153/comparison-of-the-acute-inhibitory-effects-of-tetrodotoxin-ttx-in-rat-and-human-neuronal-networks-for-risk-assessment-purposes
#14
Emma E J Kasteel, Remco H S Westerink
Tetrodotoxin (TTX) is an extremely toxic marine neurotoxin. TTX inhibits voltage-gated sodium channels, resulting in a potentially lethal inhibition of neurotransmission. Despite numerous intoxications in Asia and Europe, limited (human) toxicological data are available for TTX. Additionally, the degree of interspecies differences for TTX is not well established, hampering the use of available (animal) data for human risk assessment and establishing regulatory limits for TTX concentrations in (shell)fish. We therefore used micro-electrode array (MEA) recordings as an integrated measure of neurotransmission to demonstrate that TTX inhibits neuronal electrical activity in both primary rat cortical cultures and human-induced pluripotent stem cell (hIPSC)-derived iCell(®) neurons in co-culture with hIPSC-derived iCell(®) astrocytes, with IC50 values of 7 and 10nM, respectively...
February 9, 2017: Toxicology Letters
https://www.readbyqxmd.com/read/28191886/sirtuin-1-regulates-cardiac-electrical-activity-by-deacetylating-the-cardiac-sodium-channel
#15
Ajit Vikram, Christopher M Lewarchik, Jin-Young Yoon, Asma Naqvi, Santosh Kumar, Gina M Morgan, Julia S Jacobs, Qiuxia Li, Young-Rae Kim, Modar Kassan, Jing Liu, Mohanad Gabani, Ajay Kumar, Haider Mehdi, Xiaodong Zhu, Xiaoqun Guan, William Kutschke, Xiaoming Zhang, Ryan L Boudreau, Shengchuan Dai, Daniel S Matasic, Saet-Byel Jung, Kenneth B Margulies, Vikas Kumar, Markus M Bachschmid, Barry London, Kaikobad Irani
The voltage-gated cardiac Na(+) channel (Nav1.5), encoded by the SCN5A gene, conducts the inward depolarizing cardiac Na(+) current (INa) and is vital for normal cardiac electrical activity. Inherited loss-of-function mutations in SCN5A lead to defects in the generation and conduction of the cardiac electrical impulse and are associated with various arrhythmia phenotypes. Here we show that sirtuin 1 deacetylase (Sirt1) deacetylates Nav1.5 at lysine 1479 (K1479) and stimulates INa via lysine-deacetylation-mediated trafficking of Nav1...
February 13, 2017: Nature Medicine
https://www.readbyqxmd.com/read/28188741/molecular-dynamics-study-of-ion-transport-through-an-open-model-of-voltage-gated-sodium-channel
#16
Yang Li, Ruining Sun, Huihui Liu, Haipeng Gong
Voltage-gated sodium (NaV) channels are critical in the signal transduction of excitable cells. In this work, we modeled the open conformation for the pore domain of a prokaryotic NaV channel (NaVRh), and used molecular dynamics simulations to track the translocation of dozens of Na(+) ions through the channel in the presence of a physiological transmembrane ion concentration gradient and a transmembrane electrical field that was closer to the physiological one than previous studies. Channel conductance was then estimated from simulations on the wide-type and DEKA mutant of NaVRh...
February 8, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28188450/terminal-latency-abnormality-in-amyotrophic-lateral-sclerosis-without-split-hand-syndrome
#17
Donghwi Park, Jin-Sung Park
Amyotrophic lateral sclerosis (ALS) has a peculiar involvement pattern; clinically it is known as split hand syndrome and electrophysiologically shows abnormalities in the abductor pollicis brevis (APB)/abductor digiti minimi (ADM) ratio. The aim of this study was to find a significant electrophysiological parameter in upper limb onset ALS patients with normal APB/ADM ratio when compared to cervical spondylotic amyotrophy (CSA) and healthy controls. We retrospectively reviewed the electrophysiological results of 47 upper limb onset ALS and 42 CSA cases; 20 healthy individuals were included as controls...
February 10, 2017: Neurological Sciences
https://www.readbyqxmd.com/read/28188357/analgesic-antiallodynic-and-anticonvulsant-activity-of-novel-hybrid-molecules-derived-from-n-benzyl-2-2-5-dioxopyrrolidin-1-yl-propanamide-and-2-2-5-dioxopyrrolidin-1-yl-butanamide-in-animal-models-of-pain-and-epilepsy
#18
Anna Rapacz, Krzysztof Kamiński, Jolanta Obniska, Paulina Koczurkiewicz, Elżbieta Pękala, Barbara Filipek
The purpose of the present study was to examine the analgesic activity of six novel hybrid molecules, which demonstrated in the previous research anticonvulsant activity in the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole seizure (scPTZ) tests in mice. The antinociceptive properties were estimated in three models of pain in mice-the hot plate test, the formalin test, and in the oxaliplatin-induced neuropathy. Moreover, extended anticonvulsant studies were carried out and the antiseizure activity was investigated in the 6-Hz test...
February 10, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28186665/dexmedetomidine-enhances-human-lung-fluid-clearance-through-improving-alveolar-sodium-transport
#19
Yong Cui, Yan Ding, Lei Chen, Yue Li, Yan Chun Li, Hongguang Nie
Accumulating evidence shows that dexmedetomidine can attenuate lung edema with acute lung injury in experimental mouse and rat models, but the mechanisms of dexmedetomidine on human alveolar fluid transport are still unknown. We measured the effects of dexmedetomidine on alveolar fluid clearance in human lung lobes ex vivo. Moreover, we measured the regulation of transepithelial Na(+) transport by dexmedetomidine in H441 cells by electrophysiological technique and western blot method. Our results showed that intratracheal instillation of dexmedetomidine markedly increased the re-absorption of 5% bovine serum albumin instillate (19...
February 10, 2017: Fundamental & Clinical Pharmacology
https://www.readbyqxmd.com/read/28184187/ankyrin-g-membrane-partners-drive-the-establishment-and-maintenance-of-the-axon-initial-segment
#20
Christophe Leterrier, Nadine Clerc, Fanny Rueda-Boroni, Audrey Montersino, Bénédicte Dargent, Francis Castets
The axon initial segment (AIS) is a highly specialized neuronal compartment that plays a key role in neuronal development and excitability. It concentrates multiple membrane proteins such as ion channels and cell adhesion molecules (CAMs) that are recruited to the AIS by the scaffold protein ankyrin G (ankG). The crucial function of ankG in the anchoring of AIS membrane components is well established, but a reciprocal role of membrane partners in ankG targeting and stabilization remained elusive. In rat cultured hippocampal neurons and cortical organotypic slices, we found that shRNA-mediated knockdown of ankG membrane partners (voltage-gated sodium channels (Nav) or neurofascin-186) led to a decrease of ankG concentration and perturbed the AIS formation and maintenance...
2017: Frontiers in Cellular Neuroscience
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