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stretch channels

Geoffrey W Abbott
The human ventricular cardiomyocyte transient outward K(+) current (Ito) mediates the initial phase of myocyte repolarization and its disruption is implicated in Brugada Syndrome and heart failure (HF). Human cardiac Ito is generated primarily by two Kv4.3 splice variants (Kv4.3L and Kv4.3S, diverging only by a C-terminal, S6-proximal, 19-residue stretch unique to Kv4.3L), which are differentially remodeled in HF, but considered functionally alike at baseline. Kv4.3 is regulated in human heart by β subunits including KChIP2b and KCNEs, but their effects were previously assumed to be Kv4...
2017: Frontiers in Physiology
S A Gudipaty, J Lindblom, P D Loftus, M J Redd, K Edes, C F Davey, V Krishnegowda, J Rosenblatt
Despite acting as a barrier for the organs they encase, epithelial cells turn over at some of the fastest rates in the body. However, epithelial cell division must be tightly linked to cell death to preserve barrier function and prevent tumour formation. How does the number of dying cells match those dividing to maintain constant numbers? When epithelial cells become too crowded, they activate the stretch-activated channel Piezo1 to trigger extrusion of cells that later die. However, it is unclear how epithelial cell division is controlled to balance cell death at the steady state...
February 15, 2017: Nature
Dongshuai Hou, Chuanlin Hu, Zongjin Li
Reactive force field molecular dynamics was utilized to investigate the structure, dynamics, and mechanical nature of different cations solvated in the nanometer-channel of highly disordered calcium silicate hydrate. The local structures of different cations bonded with hydroxyl groups are characterized by the long spatial correlation, bond angel distribution preference, and featured coordinated number, resembling those of the tetra-/penta-/octahedron for cation-oxygen structure in the defective region of the silicate glass...
February 20, 2017: Inorganic Chemistry
Martin Horáček, Lukáš Indra, Jonathan T Green, Jack A Naylon, Boguslaw Tykalewicz, Jakub Novák, František Batysta, Tomáš Mazanec, Jakub Horáček, Roman Antipenkov, Zbyněk Hubka, Robert Boge, Pavel Bakule, Bedřich Rus
We report on the design and performance of a fiber-based, multi-channel laser amplifier seed pulse distribution system. The device is designed to condition and distribute low energy laser pulses from a mode-locked oscillator to multiple, highly synchronized, high energy amplifiers integrated into a laser beamline. Critical functions such as temporal pulse stretching well beyond 100 ps/nm, pulse picking, and fine control over the pulse delay up to 300 ps are all performed in fiber eliminating the need for bulky and expensive grating stretchers, Pockels cells, and delay lines...
January 2017: Review of Scientific Instruments
Katherine J Catani, Giel Muller, Gabriel da Silva, Evan J Bieske
The electronic spectrum of the methyl propargyl cation (2-butyn-1-yl cation, H2C4H3(+)) is measured over the 230-270 nm range by photodissociating the bare cation and its Ar and N2 tagged complexes in a tandem mass spectrometer. The observed A'1←A'1 band system has an origin at 37 753 cm(-1) for H2C4H3(+), 37738 cm(-1) for H2C4H3(+)-Ar, and 37 658 cm(-1) for H2C4H3(+)-N2. The methyl propargyl cation photodissociates to produce either C2H3(+)+C2H2 (protonated acetylene + acetylene) or H2C4H(+)+H2 (protonated diacetylene + dihydrogen)...
January 28, 2017: Journal of Chemical Physics
Peter Chen, Renana Gershoni-Poranne
A comprehensive investigation, utilizing Valence Bond and Molecular Orbitals based techniques, reveals that the C-N bonds in protonated and methylated ammoniums are Charge Shift Bonds. Moreover, the ammoniums are found to be predominantly covalent at the equilibrium distance, yet have two competing dissociation channels, which determine whether or not a state function crossing occurs during dissociation. We show that the location of the crossing point can be predicted with relative ionization potentials, and may be tuned by altering the stabilization of the respective fragments...
February 1, 2017: Chemistry: a European Journal
Han-Chiao Isaac Chen, John Wolf, Douglas Smith
OBJECTIVE: Although substantial progress has been made in mapping the connections of the brain, less is known about how this organization translates into brain function. In particular, the massive interconnectivity of the brain has made it difficult to specifically examine data transmission between two nodes of the connectome, a central component of the "neural code." Here, we investigated the propagation of multiple streams of asynchronous neuronal activity across an isolated in vitro "connectome unit...
January 31, 2017: Journal of Neural Engineering
M Rocio Servin-Vences, Mirko Moroni, Gary R Lewin, Kate Poole
The joints of mammals are lined with cartilage, comprised of individual chondrocytes embedded in a specialized extracellular matrix. Chondrocytes experience a complex mechanical environment and respond to changing mechanical loads in order to maintain cartilage homeostasis. It has been proposed that mechanically gated ion channels are of functional importance in chondrocyte mechanotransduction; however, direct evidence of mechanical current activation in these cells has been lacking. We have used high-speed pressure clamp and elastomeric pillar arrays to apply distinct mechanical stimuli to primary murine chondrocytes, stretch of the membrane and deflection of cell-substrate contacts points, respectively...
January 30, 2017: ELife
Dongwook Kim, Jaehun Park, Yung Sam Kim, Myoung Soo Lah
The MOF with the encapsulated CO2 molecule shows that the CO2 molecule is ligated to the unsaturated Cu(II) sites in the cage using its Lewis basic oxygen atom via an angular η(1)-(OA) coordination mode and also interacts with Lewis basic nitrogen atoms of the tetrazole ligands using its Lewis acidic carbon atom. Temperature dependent structure analyses indicate the simultaneous weakening of both interactions as temperature increases. Infrared spectroscopy of the MOF confirmed that the CO2 interaction with the framework is temperature dependent...
January 27, 2017: Scientific Reports
Dario Ivan Carrasco, Jacob A Vincent, Timothy C Cope
Knowledge of the molecular mechanisms underlying signaling of mechanical stimuli by muscle spindles remains incomplete. In particular, the ionic conductances that sustain tonic firing during static muscle stretch are unknown. We hypothesized that tonic firing by spindle afferents depends on sodium persistent inward current (INaP), and we tested for the necessary presence of the appropriate voltage-gated sodium (NaV) channels in primary sensory endings. We began study of the NaV1.6 isoform, selected both for its capacity to produce INaP and for its presence in other mechanosensors that fire tonically...
January 25, 2017: Journal of Neurophysiology
Chao Wang, Sung-Wook Nam, John M Cotte, Christopher V Jahnes, Evan G Colgan, Robert L Bruce, Markus Brink, Michael F Lofaro, Jyotica V Patel, Lynne M Gignac, Eric A Joseph, Satyavolu Papa Rao, Gustavo Stolovitzky, Stanislav Polonsky, Qinghuang Lin
Wafer-scale fabrication of complex nanofluidic systems with integrated electronics is essential to realizing ubiquitous, compact, reliable, high-sensitivity and low-cost biomolecular sensors. Here we report a scalable fabrication strategy capable of producing nanofluidic chips with complex designs and down to single-digit nanometre dimensions over 200 mm wafer scale. Compatible with semiconductor industry standard complementary metal-oxide semiconductor logic circuit fabrication processes, this strategy extracts a patterned sacrificial silicon layer through hundreds of millions of nanoscale vent holes on each chip by gas-phase Xenon difluoride etching...
January 23, 2017: Nature Communications
Yohei Yamaguchi, Gentaro Iribe, Toshiyuki Kaneko, Ken Takahashi, Takuro Numaga-Tomita, Motohiro Nishida, Lutz Birnbaumer, Keiji Naruse
When a cardiac muscle is held in a stretched position, its [Ca(2+)] transient increases slowly over several minutes in a process known as stress-induced slow increase in intracellular Ca(2+) concentration ([Ca(2+)]i) (SSC). Transient receptor potential canonical (TRPC) 3 forms a non-selective cation channel regulated by the angiotensin II type 1 receptor (AT1R). In this study, we investigated the role of TRPC3 in the SSC. Isolated mouse ventricular myocytes were electrically stimulated and subjected to sustained stretch...
January 19, 2017: Journal of Physiological Sciences: JPS
Vilhelm Müller, Fredrik Westerlund
Optical DNA mapping has over the last decade emerged as a very powerful tool for obtaining long range sequence information from single DNA molecules. In optical DNA mapping, intact large single DNA molecules are labeled, stretched out, and imaged using a fluorescence microscope. This means that sequence information ranging over hundreds of kilobasepairs (kbp) can be obtained in one single image. Nanochannels offer homogeneous and efficient stretching of DNA that is crucial to maximize the information that can be obtained from optical DNA maps...
January 18, 2017: Lab on a Chip
You-Min Lin, Yu Fu, John Winston, Ravi Radhakrishnan, Sushil K Sarna, Li-Yen M Huang, Xuan-Zheng Shi
Abdominal pain is one of the major symptoms in bowel obstruction (BO); its cellular mechanisms remain incompletely understood. We tested the hypothesis that mechanical stress in obstruction upregulates expression of nociception mediator nerve growth factor (NGF) in gut smooth muscle cells (SMC), and NGF sensitizes primary sensory nerve to contribute to pain in BO. Partial colon obstruction was induced with a silicon band implanted in the distal bowel of Sprague-Dawley rats. Colon-projecting sensory neurons in the dorsal root ganglia (DRG, T13 to L2) were identified for patch clamp and gene expression studies...
January 6, 2017: Pain
Yaping Li, Tao Xu, Xiaomei Chen, Shin Lin, Michael Cho, Dong Sun, Mengsu Yang
Tumor metastasis is the primary cause of cancer death. Numerous studies have demonstrated the electrotactic responses of various cancer cell types, and suggested its potential implications in metastasis. In this study, we used a microfluidic device to emulate endogenous direct current electric field (dcEF) environment, and studied the electrotactic migration of non-small cell lung cancer cell lines (H460, HCC827, H1299, and H1975) and the underlying mechanisms. These cell lines exhibited greatly different response in applied dcEFs (2-6 V/cm)...
January 11, 2017: Analytical and Bioanalytical Chemistry
Grim Keulemans, Frederik Ceyssens, Robert Puers
A robust and low cost ionic liquid based strain sensor is fabricated for high strain measurements in biomedical applications (up to 40 % and higher). A tubular 5 mm long silicone microchannel with an inner diameter of 310 µm and an outer diameter of 650 µm is filled with an ionic liquid. Three ionic liquids have been investigated: 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, ethylammonium nitrate and cholinium ethanoate. When the channel is axially stretched, geometrical deformations change the electrical impedance of the liquid channel...
March 2017: Biomedical Microdevices
Ruchika Gangwar, Avtar Meena, Pradeep Shukla, Archana Nagaraja, Piotr Dorniak, Sandeep Pallikuth, Christopher Waters, Anil Sood, Radhakrishna Rao
The role of reactive oxygen species (ROS) in osmotic stress, dextran sulfate sodium (DSS) and cyclic stretch-induced tight junction disruption was investigated in Caco-2 cell monolayers in vitro , and restraint stress-induced barrier dysfunction in mouse colon in vivo Live cell imaging showed that osmotic stress, cyclic stretch and DSS triggered rapid production of ROS in Caco-2 cell monolayers, which was blocked by depletion of intracellular Ca(2+) by BAPTA. Knockdown of CaV1.3 or TRPV6 channels blocked osmotic stress and DSS-induced ROS production and attenuated tight junction disruption and barrier dysfunction...
January 5, 2017: Biochemical Journal
C A Cobine, E E Hannah, M H Zhu, H E Lyle, J R Rock, K M Sanders, S M Ward, K D Keef
The mechanism underlying tone generation in the internal anal sphincter (IAS) is controversial. We examined the hypothesis that tone depends upon generation of electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC-IM) by activation of Ca(2+) -activated Cl(-) channels (encoded by Ano1) and voltage-dependent L-type Ca(2+) channels (encoded by Cacna1c). Phasic contractions and tone in the IAS were nearly abolished by ANO1 and CavL antagonists. ANO1 antagonists also abolished SWs as well as transient depolarizations that persisted after addition of CavL antagonists...
January 4, 2017: Journal of Physiology
Beatriz Miguel, José Zúñiga, Alberto Requena, Adolfo Bastida
The molecular dynamics with quantum transitions method is used to study the vibrational relaxation of the OD stretching mode of HOD dissolved in liquid H2O water at 303 K. All the vibrational modes of the solute and solvent molecules that participate in the relaxation process are described by quantum mechanics, while the rotational and translational degrees of freedom are treated classically. A modification of the water intramolecular SPC/E (Simple Point Charge/Extended) force field providing vibrational frequencies in solution closer to the experimental values is proposed to analyze the influence of the vibrational energy gaps on the relaxation channels...
December 28, 2016: Journal of Chemical Physics
Daisuke Onoshima, Yoshinobu Baba
The method described here enables the automatic stretching and patterning of single DNA molecules onto a solid surface. It does not require chemical modification of the DNA or surface modification of the substrate. To detect a signal variation caused by sequence-specific dye binding or partial melting, it is crucial that the DNA molecules are arrayed in a parallel direction inside the narrow microscopic field. The method uses zigzag-shaped microgrooves in a densely-arranged molecular patterning apparatus in a microfluidic channel...
2017: Methods in Molecular Biology
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