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Sample records for tetrameric potassium ion

  1. The lysosomal potassium channel TMEM175 adopts a novel tetrameric architecture

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    Lee, Changkeun; Guo, Jiangtao; Zeng, Weizhong; Kim, Sunghoon; She, Ji; Cang, Chunlei; Ren, Dejian; Jiang , Youxing (UPENN); (UTSMC); (HHMI)

    2017-07-19

    TMEM175 is a lysosomal K+ channel that is important for maintaining the membrane potential and pH stability in lysosomes1. It contains two homologous copies of a six-transmembrane-helix (6-TM) domain, which has no sequence homology to the canonical tetrameric K+ channels and lacks the TVGYG selectivity filter motif found in these channels2, 3, 4. The prokaryotic TMEM175 channel, which is present in a subset of bacteria and archaea, contains only a single 6-TM domain and functions as a tetramer. Here, we present the crystal structure of a prokaryotic TMEM175 channel from Chamaesiphon minutus, CmTMEM175, the architecture of which represents a completely different fold from that of canonical K+ channels. All six transmembrane helices of CmTMEM175 are tightly packed within each subunit without undergoing domain swapping. The highly conserved TM1 helix acts as the pore-lining inner helix, creating an hourglass-shaped ion permeation pathway in the channel tetramer. Three layers of hydrophobic residues on the carboxy-terminal half of the TM1 helices form a bottleneck along the ion conduction pathway and serve as the selectivity filter of the channel. Mutagenesis analysis suggests that the first layer of the highly conserved isoleucine residues in the filter is primarily responsible for channel selectivity. Thus, the structure of CmTMEM175 represents a novel architecture of a tetrameric cation channel whose ion selectivity mechanism appears to be distinct from that of the classical K+ channel family.

  2. Proapoptotic Role of Potassium Ions in Liver Cells

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    Zhenglin Xia

    2016-01-01

    Full Text Available Potassium channels are transmembrane proteins that selectively promote the infiltration of potassium ions. The significance of these channels for tumor biology has become obvious. However, the effects of potassium ions on the tumor or normal cells have seldom been studied. To address this problem, we studied the biological effects of L02 and HepG2 cells with ectogenous potassium ions. Cell proliferation, cell cycle, and apoptosis rate were analyzed. Our results indicated that potassium ions inhibited proliferation of L02 and HepG2 cells and promoted their apoptosis. Potassium ions induced apoptosis through regulating Bcl-2 family members and depolarized the mitochondrial membrane, especially for HepG2 cell. These biological effects were associated with channel protein HERG. By facilitating expression of channel protein HERG, potassium ions may prevent it from being shunted to procancerous pathways by inducing apoptosis. These results demonstrated that potassium ions may be a key regulator of liver cell function. Thus, our findings suggest that potassium ions could inhibit tumorigenesis through inducing apoptosis of hepatoma cells by upregulating potassium ions transport channel proteins HERG and VDAC1.

  3. Bioinspired Artificial Sodium and Potassium Ion Channels.

    Science.gov (United States)

    Rodríguez-Vázquez, Nuria; Fuertes, Alberto; Amorín, Manuel; Granja, Juan R

    2016-01-01

    In Nature, all biological systems present a high level of compartmentalization in order to carry out a wide variety of functions in a very specific way. Hence, they need ways to be connected with the environment for communication, homeostasis equilibrium, nutrition, waste elimination, etc. The biological membranes carry out these functions; they consist of physical insulating barriers constituted mainly by phospholipids. These amphipathic molecules spontaneously aggregate in water to form bilayers in which the polar groups are exposed to the aqueous media while the non-polar chains self-organize by aggregating to each other to stay away from the aqueous media. The insulating properties of membranes are due to the formation of a hydrophobic bilayer covered at both sides by the hydrophilic phosphate groups. Thus, lipophilic molecules can permeate the membrane freely, while the small charged or very hydrophilic molecules require the assistance of other membrane components in order to overcome the energetic cost implied in crossing the non-polar region of the bilayer. Most of the large polar species (such as oligosaccharides, polypeptides or nucleic acids) cross into and out of the cell via endocytosis and exocytosis, respectively. Nature has created a series of systems (carriers and pores) in order to control the balance of small hydrophilic molecules and ions. The most important structures to achieve these goals are the ionophoric proteins that include the channel proteins, such as the sodium and potassium channels, and ionic transporters, including the sodium/potassium pumps or calcium/sodium exchangers among others. Inspired by these, scientists have created non-natural synthetic transporting structures to mimic the natural systems. The progress in the last years has been remarkable regarding the efficient transport of Na(+) and K(+) ions, despite the fact that the selectivity and the ON/OFF state of the non-natural systems remain a present and future challenge.

  4. [Topology of the mitochondrial potassium ion channels].

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    Laskowski, Michał; Kulawiak, Bogusz

    In the inner mitochondrial membrane several potassium channels have been identified whose activation lead to cytoprotection during ischemic event. It was found that activation of mitochondrial large conductance calcium activated potassium channel (mitoBKCa) and ATP regulated potassium channel (mitoKATP) preserves brain and heart muscle cells against ischemia/reperfusion induced damage. However the detailed cytoprotection mechanism remains unclear. Similarly, the molecular structures and protein interactions of the mitochondrial potassium channels are still unknown. In this article, we summarize the current knowledge of the mitoKATP and mitoBKCa channels topology. Different aspects of this topic are discussed like import and assembly of the channel subunits and biophysical properties of mitochondrial compartments. Additionally, the consequences of different topology models on the cytoprotective function of the mitochondrial potassium channels were analyzed.

  5. Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous potassium-ion storage

    OpenAIRE

    Charles, Daniel Scott; Feygenson, Mikhail; Page, Katharine; Neuefeind, Joerg; Xu, Wenqian; Teng, Xiaowei

    2017-01-01

    Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because the large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of ...

  6. Release of Potassium Ion and Calcium Ion from Phosphorylcholine Group Bearing Hydrogels

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    Kazuhiko Ishihara

    2013-11-01

    Full Text Available In an attempt to recreate the microenvironment necessary for directed hematopoietic stem cell differentiation, control over the amount of ions available to the cells is necessary. The release of potassium ion and calcium ion via the control of cross-linking density of a poly(2-hydroxyethyl methacrylate (pHEMA-based hydrogel containing 1 mol % 2-methacryloyloxyethyl phosphorylcholine (MPC and 5 mol % oligo(ethylene glycol (400 monomethacrylate [OEG(400MA] was investigated. Tetra(ethylene glycol diacrylate (TEGDA, the cross-linker, was varied over the range of 1–12 mol %. Hydrogel discs (ϕ = 4.5 mm and h = 2.0 mm were formed by UV polymerization within silicone isolators to contain 1.0 M CaCl2 and 0.1 M KCl, respectively. Isothermal release profiles, were measured at 37 °C in 4-(2-hydroxyethyl-1-piperazineethanesulfonic acid sodium salt (HEPES buffer using either calcium ion or potassium ion selective electrodes (ISE. The resulting release profiles were found to be independent of cross-linking density. Average (n = 3 release profiles were fit to five different release models with the Korsmeyer-Peppas equation, a porous media transport model, exhibiting the greatest correlation (R2 > 0.95. The diffusion exponent, n was calculated to be 0.24 ± 0.02 and 0.36 ± 0.04 for calcium ion and potassium ion respectively indicating non-Fickian diffusion. The resulting diffusion coefficients were calculated to be 2.6 × 10−6 and 11.2 × 10−6 cm2/s, which compare well to literature values of 2.25 × 10−6 and 19.2 × 10−6 cm2/s for calcium ion and potassium ion, respectively.

  7. Determination of chlorate in potassium perchlorate pyrotechnic material by specific ion electrode

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    Yates, W.G.

    1976-08-31

    A method for the determination of chlorate ion in potassium perchlorate was developed. The analytical method utilized a reduction of the chlorate ion to the chloride ion with ferrous ammonium sulfate. The chloride ions produced by this reduction step were then determined with a specific ion electrode technique. The amount of chlorate ion was determined by calculating how much chlorate ion was represented by the analyzed chloride ion making an appropriate adjustment for the amount of free chloride ion found in the potassium perchlorate and deionized water.

  8. Potassium

    Science.gov (United States)

    ... and blackberries Root vegetables, such as carrots and potatoes Citrus fruits, such as oranges and grapefruit Your kidneys help to keep the right amount of potassium in your body. If you have chronic kidney disease, your kidneys may not remove extra potassium from ...

  9. Characterization for organic ion-sensitive field effect transistor response for measurement of physiological potassium ion-concentration measurement

    Science.gov (United States)

    Rai, Pratysh; Jung, Soyoun; Ji, Taeksoo; Varadan, Vijay K.

    2009-03-01

    Potassium ion monitoring, in human body, is important for diagnostic and therapeutic purposes. The dynamic response of potassium selective ISFET sensors is instrumental in formulating calibration schema and signal compensations to correct systematic errors. In the research reported here, response characteristics of potassium selective ISFETs were studied. The range of detection was set between 1mM and 25mM to cover all the physiological potassium concentrations. The signals were obtained from an array of sensors, with different aspect ratios, by varying potassium ion concentrations in a time dependent fashion. Normalization of the drain current was used to compensation for variance in order of magnitude observed in different sensors. Sensor response time and linear response range were analyzed, in relation to difference in aspect ratios. Probable modifications in calibration scheme and compensation technique, subjective to the findings, have been suggested.

  10. Storage of potassium ions in layered vanadium pentoxide nanofiber electrodes for aqueous pseudocapacitors.

    Science.gov (United States)

    Yeager, Matthew P; Du, Wenxin; Bishop, Brendan; Sullivan, Matthew; Xu, Wenqian; Su, Dong; Senanayake, Sanjaya D; Hanson, Jonathan; Teng, Xiaowei

    2013-12-01

    Spaced out: This paper investigates potassium-ion storage in vanadium pentoxide nanofibers (VNFs, K0.33 V2 O5 ) with a layered architecture. In situ XRD experiments reveal that the interplanar space of VNF expands/contracts upon extraction/insertion of potassium ions during the redox process. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Potassium-Based Dual Ion Battery with Dual-Graphite Electrode.

    Science.gov (United States)

    Fan, Ling; Liu, Qian; Chen, Suhua; Lin, Kairui; Xu, Zhi; Lu, Bingan

    2017-08-01

    A potassium ion battery has potential applications for large scale electric energy storage systems due to the abundance and low cost of potassium resources. Dual graphite batteries, with graphite as both anode and cathode, eliminate the use of transition metal compounds and greatly lower the overall cost. Herein, combining the merits of the potassium ion battery and dual graphite battery, a potassium-based dual ion battery with dual-graphite electrode is developed. It delivers a reversible capacity of 62 mA h g -1 and medium discharge voltage of ≈3.96 V. The intercalation/deintercalation mechanism of K + and PF 6 - into/from graphite is proposed and discussed in detail, with various characterizations to support. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Mechanistic elucidation of thermal runaway in potassium-ion batteries

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    Adams, Ryan A.; Varma, Arvind; Pol, Vilas G.

    2018-01-01

    For the first time, thermal runaway of charged graphite anodes for K-ion batteries is investigated, using differential scanning calorimetry (DSC) to probe the exothermic degradation reactions. Investigated parameters such as state of charge, cycle number, surface area, and binder demonstrate strong influences on the DSC profiles. Thermal runaway initiates at 100 °C owing to KxC8 - electrolyte reactions, but the K-ion graphite anode evolves significantly less heat as compared to the analogous Li-ion system (395 J g-1 vs. 1048 J g-1). The large volumetric expansion of graphite during potassiation cracks the SEI layer, enabling contact and reaction of KC8 - electrolyte, which diminishes with cycle number due to continuous SEI growth. High surface area graphite decreases the total heat generation, owing to thermal stability of the K-ion SEI layer. These findings illustrate the dynamic nature of K-ion thermal runaway and its many contrasts with the Li-ion graphite system, permitting possible engineering solutions for safer batteries.

  13. Mechanism of potassium ion uptake by the Na+/K+-ATPase

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    Castillo, Juan P.; Rui, Huan; Basilio, Daniel; Das, Avisek; Roux, Benoît; Latorre, Ramon; Bezanilla, Francisco; Holmgren, Miguel

    2015-07-01

    The Na+/K+-ATPase restores sodium (Na+) and potassium (K+) electrochemical gradients dissipated by action potentials and ion-coupled transport processes. As ions are transported, they become transiently trapped between intracellular and extracellular gates. Once the external gate opens, three Na+ ions are released, followed by the binding and occlusion of two K+ ions. While the mechanisms of Na+ release have been well characterized by the study of transient Na+ currents, smaller and faster transient currents mediated by external K+ have been more difficult to study. Here we show that external K+ ions travelling to their binding sites sense only a small fraction of the electric field as they rapidly and simultaneously become occluded. Consistent with these results, molecular dynamics simulations of a pump model show a wide water-filled access channel connecting the binding site to the external solution. These results suggest a mechanism of K+ gating different from that of Na+ occlusion.

  14. A highly selective, colorimetric, and environment-sensitive optical potassium ion sensor.

    Science.gov (United States)

    Song, Guangjie; Sun, Ruofan; Du, Jiqing; Chen, Meiwan; Tian, Yanqing

    2017-05-18

    Potassium ions (K+) play vital roles in many biological processes and thus highly selective sensors for K+ are critical for disease diagnosis and health monitoring. Herein, we report a colorimetric K+ sensor (KS7) in which a hemicyanine dye was used as a fluorophore and phenylaza-[18]crown-6 lariat ether (ACLE) was utilized as a K+ ligand. The maximum absorption peak of KS7 shifted hypsochromically by 77 nm (from 515 to 438 nm) with an isosbestic point at 452 nm upon the addition of K+ to its aqueous solution accompanied by a color change from red to yellow. This sensor exhibited a linear response range to K+ from 1 to 200 mM, indicating its wide detection range for cellular, urinary, and environmental potassium ions. Further, this sensor is solvent-sensitive, implying its environmental sensitivity. For the demonstration of its applications, we prepared filter paper-based K+ test strips, which were used to detect K+ in urine conveniently.

  15. Recent research progress in non-aqueous potassium-ion batteries.

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    Zou, Xiaoxi; Xiong, Peixun; Zhao, Jin; Hu, Jimin; Liu, Zhitian; Xu, Yunhua

    2017-10-11

    Large-scale energy storage technologies are in high demand for effective utilization of intermittent electricity generations and efficient electric power transmission. The feasibility of lithium-ion batteries for large-scale energy storage is under debate due to the scarcity and uneven distribution of lithium resources in the Earth's crust. Therefore, there arises tremendous interest in pursuing alternative energy storage systems based on earth-abundant materials. Recently, non-aqueous potassium-ion batteries (KIBs) are emerging as a promising energy storage system due to the abundance of potassium and the encouraging battery performance. Here, the recent research progress in non-aqueous KIBs is summarized, including electrode materials, electrolytes, battery architectures and fundamental electrochemical processes. The challenges and future research opportunities are also briefly discussed.

  16. Plausibility of potassium ion-exchanged ZSM-5 as soot combustion catalysts.

    Science.gov (United States)

    Lu, Chenxi; Liu, Taizheng; Shi, Qiaolan; Li, Qian; Xin, Ying; Zheng, Lei; Zhang, Zhaoliang

    2017-06-12

    Potassium (K) ion-exchanged ZSM-5 zeolites were investigated for catalytic soot combustion. X-ray absorption fine-structure (XAFS), Raman, in situ IR and NH3-temperature programmed desorption (NH3-TPD) confirmed the location of K+ at the ion-exchanged sites. Temperature-programmed oxidation (TPO) reactions showed that K-ZSM-5 decreased ignition tempeatures of soot combustion and increased selectivity to CO2. The improved activity for soot combustion by increasing K+-exchanged amounts via decreasing the Si/Al ratio reinforced the K+ ions participating in soot combustion. 18O2 isotopic isothermal reactions suggested the activation of gaseous oxygen by the K+ ions. This demonstrated a new appliction of alkali metal exchanged zeolites and the strategy for enhancement of catalytic soot combustion activity.

  17. Potassium nickel hexacyanoferrate as a high-voltage cathode material for nonaqueous magnesium-ion batteries

    Science.gov (United States)

    Chae, Munseok S.; Hyoung, Jooeun; Jang, Minchul; Lee, Hochun; Hong, Seung-Tae

    2017-09-01

    The magnesium insertion capability of Prussian blue (PB) analogue, potassium nickel hexacyanoferrate K0.86Ni[Fe(CN)6]0.954(H2O)0.766 (KNF-086), is demonstrated as a cathode material for rechargeable magnesium-ion batteries using a conventional organic electrolyte. K1.51Ni[Fe(CN)6]0.954(H2O)0.766 is synthesized first, and potassium ions are electrochemically extracted to prepare the KNF-086 cathode. The electrochemical test cell is composed of KNF-086 as the working electrode, an activated carbon as the counter and reference electrode, and 0.5 M Mg(ClO4)2 in acetonitrile as the electrolyte. The cell shows a reversible magnesium insertion/extraction reaction with a discharge capacity of 48.3 mAh g-1 at a 0.2 C rate, and an average discharge voltage at 2.99 V (vs. Mg/Mg2+) that is the highest among the cathode materials ever reported for magnesium-ion batteries. Elemental analysis and Fourier electron-density map analysis from powder X-ray diffraction data confirm that the magnesium-inserted phase is Mg0.27K0.86Ni[Fe(CN)6]0.954(H2O)0.766 (MKNF-086), and the magnesium ions in MKNF-086 are positioned at the center of the large interstitial cavities of cubic PB. Compared to KNF-086, MKNF-086 exhibits a decreased unit cell parameter (0.8%) and volume (2.4%). These results demonstrate that a PB analogue, potassium nickel hexacyanoferrate, could be utilized as a potential cathode material for conventional organic electrolyte-based magnesium-ion batteries.

  18. Ultra-light and flexible pencil-trace anode for high performance potassium-ion and lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Zhixin Tai

    2017-07-01

    Full Text Available Engineering design of battery configurations and new battery system development are alternative approaches to achieve high performance batteries. A novel flexible and ultra-light graphite anode is fabricated by simple friction drawing on filter paper with a commercial 8B pencil. Compared with the traditional anode using copper foil as current collector, this innovative current-collector-free design presents capacity improvement of over 200% by reducing the inert weight of the electrode. The as-prepared pencil-trace electrode exhibits excellent rate performance in potassium-ion batteries (KIBs, significantly better than in lithium-ion batteries (LIBs, with capacity retention of 66% for the KIB vs. 28% for the LIB from 0.1 to 0.5 A g−1. It also shows a high reversible capacity of ∼230 mAh g−1 at 0.2 A g−1, 75% capacity retention over 350 cycles at 0.4 A g−1and the highest rate performance (based on the total electrode weight among graphite electrodes for K+ storage reported so far. Keywords: Current-collector-free, Flexible pencil-trace electrode, Potassium-ion battery, Lithium-ion battery, Layer-by-layer interconnected architecture

  19. Preparation of a novel potassium ion imprinted polymeric nanoparticles based on dicyclohexyl 18C6 for selective determination of K{sup +} ion in different water samples

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, Hamid Reza, E-mail: h.rajabi@mail.yu.ac.ir [Chemistry Department, Yasouj University, Yasouj, 75918-74831 (Iran, Islamic Republic of); Shamsipur, Mojtaba [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Pourmortazavi, Seied Mahdi [Faculty of Material and Manufacturing Technologies, Malek-Ashtar University of Technology, Tehran (Iran, Islamic Republic of)

    2013-08-01

    This work reports the first application of the ion imprinting technology for determination of potassium ion by precipitation polymerization method. Ion imprinted polymeric (IIP) nanoparticles were prepared by using dicyclohexyl 18C6 (DC18C6) as a K{sup +} ion selective crown ether, in the acetonitrile–dimethylsulfoxide (3:1; v/v) mixture as porogen. The imprint potassium ion was removed from the polymeric matrix using 0.5 M HNO{sub 3}. The scanning electron microscopy (SEM) micrographs showed colloidal nanoparticles of 60–90 nm in diameter and slightly irregular in shape. The obtained ion-imprinted particles for K{sup +} showed selective recognition with rapid adsorption and desorption processes. It was found that imprinting results in increased affinity of the material toward K{sup +} ion over other competitor metal ions with the same charge and/or close ionic radius. The synthesized IIP nanobeads were shown to be promising for solid-phase extraction coupled with flame photometry for determination of trace K{sup +} ion in different water samples. Highlights: • Synthesis of nano-sized ion imprinted polymers for separation of potassium ions • Rapid kinetics of adsorption and desorption of K{sup +} ion on the resulting IIPs • First study on application of ion imprinting for detection of K{sup +} based on DC18C6 • An excellent selectivity toward K{sup +} ion over a range of strong competing metal ions.

  20. Potassium ions in SiO2: electrets for silicon surface passivation

    Science.gov (United States)

    Bonilla, Ruy S.; Wilshaw, Peter R.

    2018-01-01

    This manuscript reports an experimental and theoretical study of the transport of potassium ions in thin silicon dioxide films. While alkali contamination was largely researched in the context of MOSFET instability, recent reports indicate that potassium ions can be embedded into oxide films to produce dielectric materials with permanent electric charge, also known as electrets. These electrets are integral to a number of applications, including the passivation of silicon surfaces for optoelectronic devices. In this work, electric field assisted migration of ions is used to rapidly drive K+ into SiO2 and produce effective passivation of silicon surfaces. Charge concentrations of up to ~5  ×  1012 e cm‑2 have been achieved. This charge was seen to be stable for over 1500 d, with decay time constants as high as 17 000 d, producing an effectively passivated oxide–silicon interface with SRV  <  7 cm s‑1, in 1 Ω cm n-type material. This level of charge stability and passivation effectiveness has not been previously reported. Overall, this is a new and promising methodology to enhance surface passivation for the industrial manufacture of silicon optoelectronic devices.

  1. Probing the selective separation of potassium ion from sodium ion with cyclopentadienyl anion as receptor: a computational study.

    Science.gov (United States)

    Desai, Mittal L; Si, Mrinal Kanti; Lo, Rabindranath; Ganguly, Bishwajit

    2015-08-01

    A systematic computational study has been carried out using post-Hartree-Fock and density functional theory methods on half sandwich (M-Cp), sandwich (Cp-M-Cp), inversed sandwich (M-Cp-M), and multi-decker chain complexes of alkali metal ions (Na(+), and K(+)). The binding affinity of cyclopentadienyl anion (Cp) with K(+) and Na(+) ions has been studied in half sandwich, sandwich, inversed sandwich, and multi-decker chain complexes. These complexes have been examined in the aqueous phase. The calculated results show that Cp anion can preferentially bind with Na(+) ion over K(+) ion in aqueous phase. The results obtained from DFT calculations have been compared with the crystal structures of Cp-Na and Cp-K complexes. The Bader's atoms in molecule (AIM) analysis were performed to characterize the non-covalent cation-π interactions in the Cp-M complexes. The calculated electron density at cage critical point indicates the strength of the Cp-M complexes. Energy decomposition analysis (EDA) has also been performed to investigate the origins of these interactions. The electrostatic interaction contributes significantly to the total interaction energy in Cp-M complexes. The relative stability difference of cyclopentadienyl anion (Cp) with K(+) and Na(+) ions in aqueous phase can be exploited for the separations from mixture such as sea bittern. The lower stability of K-Cp complex can induce to precipitate the K(+) ions more easily than the corresponding Na(+) ions. Graphical Abstract Potassium ion from sodium ion with cyclopentadienyl anion as receptor.

  2. Temperature dependence of ion pairing of a potassium salt in nonaqueous liquid and polymer electrolytes: X-ray absorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.Q.; Lee, H.S.; McBreen, J. (Brookhaven National Laboratory, Upton, New York 11973 (United States)); Xu, Z.S.; Skotheim, T.A. (Moltech Corporation, Stony Brook, New York 11794-2275 (United States)); Okamoto, Y. (Polytechnic University, Brooklyn, New York 11201 (United States)); Lu, F. (CFFLS, University of Kentucky, Lexington, Kentucky 40506 (United States))

    1994-08-15

    Near-edge x-ray absorption fine structure spectroscopy was used to study the effect of temperature on ion pairing of a potassium salt in a modified carbonate (MC3) solution and in a poly(ethylene oxide)-potassium salt complex that used MC3 as a plasticizer. The modified carbonate was made by attaching three ethylene oxide units to the four position of ethylene carbonate. Spectra were obtained, at the [ital K] edge of potassium, over the temperature range of 25--110 [degree]C. Studies of reference systems showed a correlation between ion pairing and white line splitting in the near-edge region of the spectra. The degree of white line splitting was used as a qualitative indicator of the degree of ion pairing as a function of temperature. The results indicate that, in both systems, the number of ion pairs increases with increasing temperature.

  3. Ion spatial distributions at the liquid-vapor interface of aqueous potassium fluoride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M A; D' Auria, R; Kuo, I W; Krisch, M J; Starr, D E; Bluhm, H; Tobias, D J; Hemminger, J C

    2008-04-23

    X-ray photoemission spectroscopy operating under ambient pressure conditions is used to probe ion distributions throughout the interfacial region of a free-flowing aqueous liquid micro-jet of 6 M potassium fluoride. Varying the energy of the ejected photoelectrons by carrying out experiments as a function of x-ray wavelength measures the composition of the aqueous-vapor interfacial region at various depths. The F{sup -} to K{sup +} atomic ratio is equal to unity throughout the interfacial region to a depth of 2 nm. The experimental ion profiles are compared with the results of a classical molecular dynamics simulation of a 6 M aqueous KF solution employing polarizable potentials. The experimental results are in qualitative agreement with the simulations when integrated over an exponentially decaying probe depth characteristic of an APPES experiment. First principles molecular dynamics simulations have been used to calculate the potential of mean force for moving a fluoride anion across the air-water interface. The results show that the fluoride anion is repelled from the interface, and this is consistent with the depletion of F{sup -} at the interface revealed by the APPES experiment and polarizable force field-based molecular dynamics simulation. Together, the APPES and MD simulation data provide a detailed description of the aqueous-vapor interface of alkali fluoride systems. This work offers the first direct observation of the ion distribution at a potassium fluoride aqueous solution interface. The current experimental results are compared to those previously obtained for saturated solutions of KBr and KI to underscore the strong difference in surface propensity between soft/large and hard/small halide ions in aqueous solution.

  4. Ion spatial distributions at the liquid-vapor interface of aqueous potassium fluoride solutions.

    Science.gov (United States)

    Brown, Matthew A; D'Auria, Raffaella; Kuo, I-F William; Krisch, Maria J; Starr, David E; Bluhm, Hendrik; Tobias, Douglas J; Hemminger, John C

    2008-08-28

    X-Ray photoemission spectroscopy operating under ambient pressure conditions is used to probe ion distributions throughout the interfacial region of a free-flowing aqueous liquid micro-jet of 6 M potassium fluoride. Varying the energy of the ejected photoelectrons by carrying out experiments as a function of X-ray wavelength measures the composition of the aqueous-vapor interfacial region at various depths. The F(-) to K(+) atomic ratio is equal to unity throughout the interfacial region to a depth of 2 nm. The experimental ion profiles are compared with the results of a classical molecular dynamics simulation of a 6 M aqueous KF solution employing polarizable potentials. The experimental results are in qualitative agreement with the simulations when integrated over an exponentially decaying probe depth characteristic of an APPES experiment. First principles molecular dynamics simulations have been used to calculate the potential of mean force for moving a fluoride anion across the air-water interface. The results show that the fluoride anion is repelled from the interface, consistent with the depletion of F(-) at the interface revealed by the APPES experiment and polarizable force field-based molecular dynamics simulation. Together, the APPES and MD simulation data provide a detailed description of the aqueous-vapor interface of alkali fluoride systems. This work offers the first direct observation of the ion distribution at an aqueous potassium fluoride solution interface. The current experimental results are compared to those previously obtained for saturated solutions of KBr and KI to underscore the strong difference in surface propensity between soft/large and hard/small halide ions in aqueous solution.

  5. Enhanced capacity of chemically bonded phosphorus/carbon composite as an anode material for potassium-ion batteries

    Science.gov (United States)

    Wu, Xuan; Zhao, Wei; Wang, Hong; Qi, Xiujun; Xing, Zheng; Zhuang, Quanchao; Ju, Zhicheng

    2018-02-01

    Potassium-ion batteries are attracting great attention as a promising alternative to lithium-ion batteries due to the abundance and low price of potassium. Herein, the phosphorus/carbon composite, obtained by a simple ball-milling of 20 wt% commercial red phosphorus and 80 wt% graphite, is studied as a novel anode for potassium-ion batteries. Considering the high theoretical specific capacity of phosphorus and formation of stable phosphorus-carbon bond, which can alleviate the volume expansion efficiently, the phosphorus/carbon composite exhibits a high charge capacity of 323.5 mA h g-1 after 50 cycles at a current density of 50 mA g-1 with moderate rate capability and cycling stability. By the X-ray diffraction analysis, the alloying-dealloying mechanism of phosphorus is proposed to form a KP phase. Meanwhile, prepotassiation treatment is conducted to improve the low initial coulomb efficiency.

  6. Commercial expanded graphite as a low-cost, long-cycling life anode for potassium-ion batteries with conventional carbonate electrolyte

    Science.gov (United States)

    An, Yongling; Fei, Huifang; Zeng, Guifang; Ci, Lijie; Xi, Baojuan; Xiong, Shenglin; Feng, Jinkui

    2018-02-01

    Design and synthesis of capable anode materials that can store the large size K+ is the key of development for potassium-ion batteries. The low-cost and commercial expanded graphite with large particles is a graphite-derived material with good conductivity and enlarged interlayer spaces to boost the potassium ion diffusion coefficient during charge/discharge process. Thus, we achieve excellent anode performance for potassium-ion batteries based on an expanded graphite. It can deliver a capacity of 263 mAh g-1 at the rate of 10 mA g-1 and the reversible capacity remains almost unchanged after 500 cycles at a high rate of 200 mA g-1 with a coulombic efficiency of around 100%. The potassium storage mechanism is investigated by the ex situ XRD technique. This excellent potassium storage performance will make the expanded graphite promising anode candidate for potassium ion batteries.

  7. Crystal modification of iron oxide scale by potassium addition and its application to lithium-ion battery anodes

    Science.gov (United States)

    Jung, Dong-Won; Han, Sang-Wook; Kong, Byung-Seon; Oh, Eun-Suok

    2013-11-01

    This paper proposes a valuable method to reuse the iron oxide scale (IOS) often produced in the steel industry as an anode active material in lithium-ion batteries (LIBs). The IOS samples are prepared via quenching of carbon steel and simple oxidation at a high temperature with or without sequential treatment by potassium hydroxide. Morphological and physical characterizations confirm the formation of a lamellar structure of orthorhombic KFeO2 with a high degree of crystallinity in the potassium-added IOSs. Additionally, the potassium addition decreases the particle size of the crystals and increases the d-spacing between crystal layers. Electrochemical performance tests show that the discharge capacities of the IOS samples monotonically increased with increasing number of charge/discharge cycles regardless of the existence of potassium. In addition, the rate of increase is larger in the potassium-added IOS samples containing the lamellar KFeO2 structure. Consequently, after prolonged cycling (more than 500 cycles), the potassium-added IOS sample retains a discharge capacity of 1020 mAh g-1 with good cycling stability, while the IOS quenched sample only exhibits a capacity of 956 mAh g-1. This result is attributed to the unique structure of the KFeO2 crystals formed in the potassium-added IOS particles.

  8. Students' Understanding of External Representations of the Potassium Ion Channel Protein Part II: Structure-Function Relationships and Fragmented Knowledge

    Science.gov (United States)

    Harle, Marissa; Towns, Marcy H.

    2012-01-01

    Research that has focused on external representations in biochemistry has uncovered student difficulties in comprehending and interpreting external representations. This study focuses on students' understanding of three external representations (ribbon diagram, wireframe, and hydrophobic/hydrophilic) of the potassium ion channel protein. Analysis…

  9. The effect of counter-ions on the ion selectivity of potassium and sodium ions in nanopores.

    Science.gov (United States)

    Tang, Dai; Kim, Daejoong

    2014-01-01

    The ion selective transport plays an important role in the function of cell membranes, and promotes the application of artificial permeable membranes. This phenomenon has been studied in case for different diameters and functional groups of nanopores. In this work, we focus on the effect of anions on cation selectivity, in particular the influence of various halide ions on K+ and Na+ selectivity. We adopted molecular dynamics simulations with non-charged nanopores under constant temperature and uniform concentration. The results show K+-selectivity in the solution with Cl- and Na+-selectivity in the solution with Br- and I-. This selectivity, on the contrary, disappears in the solution with F-. We also investigate the change of the hydration shell of ions and cation-anion interactions between in the bulk region and in the nanopores, which could explain this selective phenomenon.

  10. Effects of protein-protein interactions and ligand binding on the ion permeation in KCNQ1 potassium channel.

    Science.gov (United States)

    Jalily Hasani, Horia; Ganesan, Aravindhan; Ahmed, Marawan; Barakat, Khaled H

    2018-01-01

    The voltage-gated KCNQ1 potassium ion channel interacts with the type I transmembrane protein minK (KCNE1) to generate the slow delayed rectifier (IKs) current in the heart. Mutations in these transmembrane proteins have been linked with several heart-related issues, including long QT syndromes (LQTS), congenital atrial fibrillation, and short QT syndrome. Off-target interactions of several drugs with that of KCNQ1/KCNE1 ion channel complex have been known to cause fatal cardiac irregularities. Thus, KCNQ1/KCNE1 remains an important avenue for drug-design and discovery research. In this work, we present the structural and mechanistic details of potassium ion permeation through an open KCNQ1 structural model using the combined molecular dynamics and steered molecular dynamics simulations. We discuss the processes and key residues involved in the permeation of a potassium ion through the KCNQ1 ion channel, and how the ion permeation is affected by (i) the KCNQ1-KCNE1 interactions and (ii) the binding of chromanol 293B ligand and its derivatives into the complex. The results reveal that interactions between KCNQ1 with KCNE1 causes a pore constriction in the former, which in-turn forms small energetic barriers in the ion-permeation pathway. These findings correlate with the previous experimental reports that interactions of KCNE1 dramatically slows the activation of KCNQ1. Upon ligand-binding onto the complex, the energy-barriers along ion permeation path are more pronounced, as expected, therefore, requiring higher force in our steered-MD simulations. Nevertheless, pulling the ion when a weak blocker is bound to the channel does not necessitate high force in SMD. This indicates that our SMD simulations have been able to discern between strong and week blockers and reveal their influence on potassium ion permeation. The findings presented here will have some implications in understanding the potential off-target interactions of the drugs with the KCNQ1/KCNE1 channel

  11. Nickel Hexacyanoferrate Nanoparticle Electrodes For Aqueous Sodium and Potassium Ion Batteries

    KAUST Repository

    Wessells, Colin D.

    2011-12-14

    The electrical power grid faces a growing need for large-scale energy storage over a wide range of time scales due to costly short-term transients, frequency regulation, and load balancing. The durability, high power, energy efficiency, and low cost needed for grid-scale storage pose substantial challenges for conventional battery technology.(1, 2)Here, we demonstrate insertion/extraction of sodium and potassium ions in a low-strain nickel hexacyanoferrate electrode material for at least five thousand deep cycles at high current densities in inexpensive aqueous electrolytes. Its open-framework structure allows retention of 66% of the initial capacity even at a very high (41.7C) rate. At low current densities, its round trip energy efficiency reaches 99%. This low-cost material is readily synthesized in bulk quantities. The long cycle life, high power, good energy efficiency, safety, and inexpensive production method make nickel hexacyanoferrate an attractive candidate for use in large-scale batteries to support the electrical grid. © 2011 American Chemical Society.

  12. Anionic forensic signatures for sample matching of potassium cyanide using high performance ion chromatography and chemometrics.

    Science.gov (United States)

    Fraga, Carlos G; Farmer, Orville T; Carman, April J

    2011-01-30

    Potassium cyanide was used as a model toxicant to determine the feasibility of using anionic impurities as a forensic signature for matching cyanide salts back to their source. In this study, portions of eight KCN stocks originating from four countries were separately dissolved in water and analyzed by high performance ion chromatography (HPIC) using an anion exchange column and conductivity detection. Sixty KCN aqueous samples were produced from the eight stocks and analyzed for 11 anionic impurities. Hierarchal cluster analysis and principal component analysis were used to demonstrate that KCN samples cluster according to source based on the concentrations of their anionic impurities. The Fisher-ratio method and degree-of-class separation (DCS) were used for feature selection on a training set of KCN samples in order to optimize sample clustering. The optimal subset of anions needed for sample classification was determined to be sulfate, oxalate, phosphate, and an unknown anion named unk5. Using K-nearest neighbors (KNN) and the optimal subset of anions, KCN test samples from different KCN stocks were correctly determined to be manufactured in the United States. In addition, KCN samples from stocks manufactured in Belgium, Germany, and the Czech Republic were all correctly matched back to their original stocks because each stock had a unique anionic impurity profile. The application of the Fisher-ratio method and DCS for feature selection improved the accuracy and confidence of sample classification by KNN. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Protective effect of magnesium and potassium ions on the permeability of the external mitochondrial membrane.

    Science.gov (United States)

    Gorgoglione, Vincenza; Laraspata, Daniela; La Piana, Gianluigi; Marzulli, Domenico; Lofrumento, Nicola Elio

    2007-05-01

    The data reported are fully consistent with the well-known observation that exogenous cytochrome c (cyto-c) molecules do not permeate through the outer membrane of mitochondria (MOM) incubated in isotonic medium (250 mM sucrose). Cyto-c is unable to accept electrons from the sulfite/cyto-c oxido-reductase (Sox) present in the intermembrane space, unless mitochondria are solubilized. Mitochondria incubated in a very high hypotonic medium (25 mM sucrose), in contrast to any expectation, continue to be not permeable to added cyto-c even if Sox and adenylate kinase are released into the medium. The succinate/exogenous cyto-c reductase activity, very low in isotonic medium, is greatly increased decreasing the osmolarity of the medium but in both cases remains insensitive to proteolysis by added trypsin. In hypotonic medium, magnesium and potassium ions have a protective effect on the release of enzymes and on the reactivity of cyto-c as electron acceptor from both sulfite and succinate; results which are consistent with the view that MOM preserves its identity and remains not permeable to exogenous cyto-c. This report strengthens the proposal, supported by previously published data that in isotonic medium the exogenous NADH/cyto-c electron transport system is catalyzed by intact mitochondria, not permeable to added cyto-c.

  14. Evaluation of potassium ion as the endothelium-derived hyperpolarizing factor (EDHF) in the bovine coronary artery.

    Science.gov (United States)

    Nelli, Silvia; Wilson, William S; Laidlaw, Hilary; Llano, Andrea; Middleton, Susan; Price, Andrew G; Martin, William

    2003-07-01

    1. This study explored the role of the potassium ion in endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation in the bovine coronary artery. 2. Bradykinin-induced, EDHF-mediated vasodilatation was blocked by the Na(+)-K(+) ATPase inhibitor, ouabain (1 micro M), in a time-dependent manner, with maximal blockade seen after 90 min. In contrast, the K(IR) channel inhibitor, Ba(2+) (30 micro M), had no effect. 3. When the potassium content of the bathing solution was increased in a single step from 5.9 to 7-19 mM, powerful vasodilatation (max. 75.9+/-3.6%) was observed. Vasodilatation was transient and, consequently, cumulative addition of potassium produced little vasodilatation, with vasoconstriction predominating at the higher concentrations. 4. The magnitude of potassium-induced vasodilatation was similar in endothelium-containing and endothelium-denuded rings, and was unaffected by Ba(2+) (30 micro M), but abolished by ouabain (1 micro M). 5. Ouabain (1 micro M, 90 min) powerfully blocked bradykinin-induced, nitric oxide-mediated vasodilatation as well as that induced by the nitrovasodilator, glyceryl trinitrate, but that induced by the K(ATP) channel opener, levcromakalim, was hardly affected. 6. Thus, activation of Na(+)-K(+) ATPase is likely to be involved in the vasodilator responses of the bovine coronary artery to both nitric oxide and EDHF. These findings, together with the ability of potassium to induce powerful, ouabain- but not Ba(2+)-sensitive, endothelium-independent vasodilatation, are consistent with this ion contributing to the EDHF response in this tissue.

  15. First prototypes of hybrid potassium-ion capacitor (KIC): An innovative, cost-effective energy storage technology for transportation applications

    Science.gov (United States)

    Le Comte, Annaïg; Reynier, Yvan; Vincens, Christophe; Leys, Côme; Azaïs, Philippe

    2017-09-01

    Hybrid supercapacitors, combining capacitive carbon-based positive electrode with a Li-ion battery-type negative electrode have been developed in the pursuit of increasing the energy density of conventional supercapacitor without impacting the power density. However, lithium-ion capacitors yet hardly meet the specifications of automotive sector. Herein we report for the first time the development of new hybrid potassium-ion capacitor (KIC) technology. Compared to lithium-ion capacitor (LIC) all strategic materials (lithium and copper) have been replaced. Excellent electrochemical performance have been achieved at a pouch cell scale, with cyclability superior to 55 000 cycles at high charge/discharge regime. For the same cell scale, the energy density is doubled compared to conventional supercapacitor up to high power regime (>1.5 kW kg-1). Finally, the technology was successfully scaled up to 18650 format leading to very promising prospects for transportation applications.

  16. Microelectrode array measurement of potassium ion channel remodeling on the field action potential duration in rapid atrial pacing rabbits model.

    Science.gov (United States)

    Sun, Juan; Yan, Huang; Wugeti, Najina; Guo, Yujun; Zhang, Ling; Ma, Mei; Guo, Xingui; Jiao, Changan; Xu, Wenli; Li, Tianqi

    2015-01-01

    Atrial fibrillation (AF) arises from abnormalities in atrial structure and electrical activity. Microelectrode arrays (MEA) is a real-time, nondestructive measurement of the resting and action potential signal, from myocardial cells, to the peripheral circuit of electrophysiological activity. This study examined the field action potential duration (fAPD) of the right atrial appendage (RAA) by MEA in rapid atrial pacing (RAP) in the right atrium of rabbits. In addition, this study also investigated the effect of potassium ion channel blockers on fAPD. 40 New Zealand white rabbits of either sex were randomly divided into 3 groups: 1) the control, 2) potassium ion channel blocker (TEA, 4-Ap and BaCl2), and 3) amiodarone groups. The hearts were quickly removed and right atrial appendage sectioned (slice thickness 500 μm). Each slice was perfused with Tyrode's solution and continuously stimulated for 30 minutes. Sections from the control group were superfused with Tyrode's solution for 10 minutes, while the blocker groups and amiodarone were both treated with their respective compounds for 10 minutes each. The fAPD of RAA and action field action potential morphology were measured using MEA. In non-pace (control) groups, fAPD was 188.33 ± 18.29 ms after Tyrode's solution superfusion, and 173.91 ± 6.83 ms after RAP. In pace/potassium ion channel groups, TEA and BaCl2 superfusion prolonged atrial field action potential (fAPD) (control vs blocker: 176.67 ± 8.66 ms vs 196.11 ± 10.76 ms, 182.22 ± 12.87 ms vs 191.11 ± 13.09 ms with TEA and BaCl2 superfusion, respectively, P action potential in animal heart slices. After superfusing potassium ion channel blockers, fAPD was prolonged. These results suggest that Ito, IKur and IK1 remodel and mediate RAP-induced atrial electrical remodeling. Amiodarone alter potassium ion channel activity (Ito, IKur, IK1 and IKs), shortening fAPD.

  17. Hemolymph osmolality and cation concentrations in Litopenaeus vannamei during exposure to artificial sea salt or a mixed-ion solution: relationship to potassium flux.

    Science.gov (United States)

    Sowers, A D; Young, S P; Grosell, M; Browdy, C L; Tomasso, J R

    2006-10-01

    Interest in culturing the Pacific white shrimp Litopenaeus vannamei in low-salinity and brackish-well waters has led to questions about the ability of this species to osmo- and ionoregulate in environments containing low concentrations of ions and in environments with ionic ratios that differ from those found in sea water. After seven days, hemolymph osmolality and potassium, sodium and calcium values were all significantly affected by salinity (as artificial sea salt) with values decreasing with decreasing salinity. These decreases were small, however, relative to decreases in salinity, indicating iono- and osmoregulation with adjustment for gradients. The hemolymph osmolality and sodium and calcium concentrations in shrimp exposed to either 2 g/L artificial sea salt or 2 g/L mixed-ion solution (a mixture of sodium, potassium, calcium, and magnesium chlorides that approximate the concentrations and ratios of these cations found in 2 g/L dilute seawater) did not differ significantly. However, hemolymph potassium levels were significantly lower in shrimp held in the mixed-ion environment. Potassium influx rates were similar in shrimp held in either artificial sea salt or mixed ions. The results of this study indicate that salinity affects hemolymph-cation concentrations and osmolality. Further, differential potassium-influx rates do not appear to be the basis for low hemolymph potassium levels observed in shrimp held in mixed-ion environments.

  18. Equilibrium of phosphointermediates of sodium and potassium ion transport adenosine triphosphatase: action of sodium ion and Hofmeister effect.

    Science.gov (United States)

    Suzuki, K; Post, R L

    1997-05-01

    Sodium and potassium ion transport adenosine triphosphatase accepts and donates a phosphate group in the course of its reaction sequence. The phosphorylated enzyme has two principal reactive states, E1P and E2P. E1P is formed reversibly from ATP in the presence of Na+ and is precursor to E2P, which equilibrates with P(i) in the presence of K+. We studied equilibrium between these states at 4 degrees C and the effect of Na+ on it. To optimize the reaction system we used a Hofmeister effect, replacing the usual anion, chloride, with a chaotropic anion, usually nitrate. We phosphorylated enzyme from canine kidney with [32P]ATP. We estimated interconversion rate constants for the reaction E1P E2P and their ratio. To estimate rate constants we terminated phosphorylation and observed decay kinetics. We observed E1P or E2P selectively by adding K+ or ADP respectively. K+ dephosphorylates E2P leaving E1P as observable species; ADP dephosphorylates E1P leaving E2P as observable species. We fitted a 2-pool model comprising two reactive species or a twin 2-pool model, comprising a pair of independent 2-pool models, to the data and obtained interconversion and hydrolysis rate constants for each state. Replacing Na+ with Tris+ or lysine+ did not change the ratio of interconversion rate constants between E1P and E2P. Thus Na+ binds about equally strongly to E1P and E2P. This conclusion is consistent with a model of Pedemonte (1988. J. Theor. Biol. 134:165-182.). We found that Na+ affected another equilibrium, that of transphosphorylation between ATP x dephosphoenzyme and ADP x E1P. We used the reactions and model of Pickart and Jencks (1982. J. Biol. Chem. 257:5319-5322.) to generate and fit data. Decreasing the concentration of Na+ 10-fold shifted the equilibrium constant 10-fold favoring ADP x E1P over ATP x dephosphoenzyme. Thus Na+ can dissociate from E1P x Na3. Furthermore, we found two characteristics of Hofmeister effects on this enzyme.

  19. A novel EIS field effect structures coated with TESUD-PPy-PVC-dibromoaza[7]helicene matrix for potassium ions detection

    Energy Technology Data Exchange (ETDEWEB)

    Tounsi, Moncef, E-mail: tounsi1981@live.fr [Laboratoire des Interfaces et des Matériaux Avancés (LIMA), Faculté des Sciences de Monastir, Université de Monastir (Tunisia); Université de Lyon, Institut de Sciences Analytiques (ISA) – UMR 5280, 5 rue de la Doua, 69100 Villeurbanne (France); Ben Braiek, Mourad [Laboratoire de Synthèse Organique Asymétrique et Catalyse Homogène, Faculté des Sciences, Université de Monastir, Avenue de l' environnement, 5019, Monastir (Tunisia); Barhoumi, Houcine [Laboratoire des Interfaces et des Matériaux Avancés (LIMA), Faculté des Sciences de Monastir, Université de Monastir (Tunisia); Baraket, Abdoullatif; Lee, Michael; Zine, Nadia [Université de Lyon, Institut de Sciences Analytiques (ISA) – UMR 5280, 5 rue de la Doua, 69100 Villeurbanne (France); Maaref, Abderrazak [Laboratoire des Interfaces et des Matériaux Avancés (LIMA), Faculté des Sciences de Monastir, Université de Monastir (Tunisia); Errachid, Abdelhamid, E-mail: abdelhamid.errachid-el-salhi@univ-lyon1.fr [Université de Lyon, Institut de Sciences Analytiques (ISA) – UMR 5280, 5 rue de la Doua, 69100 Villeurbanne (France)

    2016-04-01

    In this work, we describe the development of new Aza[7]helicene-containing PVC-based membranes for the K{sup +} ions quantification. Here, silicon nitride-based structures (Si-p/SiO{sub 2}/Si{sub 3}N{sub 4}) were developed and the surface was activated, functionalized with an aldehyde–silane (11-(Triethoxysilyl)undecanal (TESUD)), functionalized with polypyrrole (PPy), and coated with the polyvinylchloride (PVC)-membrane containing the Aza[7]helicene as ionophore. All stages of functionalization process have been thoroughly studied by contact angle measurements (CAMs) and atomic force microscopy (AFM). The developed ion-selective electrode (ISE) was then applied using electrochemical impedance spectroscopy (EIS) for the detection of potassium ions. A linear range was observed between 1.0 × 10{sup −8} M to 1.0 × 10{sup −3} M and a detection limit of 1.0 × 10{sup −8} M was observed. The EIS results have showed a good sensitivity to potassium ion using this novel technique. The target helicene exhibited good solubility and excellent thermal stability with a high decomposition temperature (Td > 300 °C) and it indicates that helicene may be a promising material as ionophore for ion-selective electrodes (ISEs) elaboration. - Highlights: • Synthesis and characterization of a new derivatives of Aza[7]helicenes • Manufacture of PPy structures on the SiO{sub 2}/Si{sub 3}N{sub 4} surface using the TESUD as cross linking agent. • The PPy fabricated microstructures can be used as support matrix in biosensing. • Impedimetric K{sup +}-ISEs was developed by using dibromoaza[7]helicene as ionophore for K{sup +} ions determination.

  20. Equilibrium of Phosphointermediates of Sodium and Potassium Ion Transport Adenosine Triphosphatase

    Science.gov (United States)

    Suzuki, Kuniaki; Post, Robert L.

    1997-01-01

    Sodium and potassium ion transport adenosine triphosphatase accepts and donates a phosphate group in the course of its reaction sequence. The phosphorylated enzyme has two principal reactive states, E1P and E2P. E1P is formed reversibly from ATP in the presence of Na+ and is precursor to E2P, which equilibrates with Pi in the presence of K+. We studied equilibrium between these states at 4°C and the effect of Na+ on it. To optimize the reaction system we used a Hofmeister effect, replacing the usual anion, chloride, with a chaotropic anion, usually nitrate. We phosphorylated enzyme from canine kidney with [32P]ATP. We estimated interconversion rate constants for the reaction E1P ⇌ E2P and their ratio. To estimate rate constants we terminated phosphorylation and observed decay kinetics. We observed E1P or E2P selectively by adding K+ or ADP respectively. K+ dephosphorylates E2P leaving E1P as observable species; ADP dephosphorylates E1P leaving E2P as observable species. We fitted a 2-pool model comprising two reactive species or a twin 2-pool model, comprising a pair of independent 2-pool models, to the data and obtained interconversion and hydrolysis rate constants for each state. Replacing Na+ with Tris+ or lysine+ did not change the ratio of interconversion rate constants between E1P and E2P. Thus Na+ binds about equally strongly to E1P and E2P. This conclusion is consistent with a model of Pedemonte (1988. J. Theor. Biol. 134:165–182.). We found that Na+ affected another equilibrium, that of transphosphorylation between ATP·dephosphoenzyme and ADP·E1P. We used the reactions and model of Pickart and Jencks (1982. J. Biol. Chem. 257:5319–5322.) to generate and fit data. Decreasing the concentration of Na+ 10-fold shifted the equilibrium constant 10-fold favoring ADP·E1P over ATP·dephosphoenzyme. Thus Na+ can dissociate from E1P·Na3. Furthermore, we found two characteristics of Hofmeister effects on this enzyme. PMID:9154903

  1. Measuring calcium, potassium, and nitrate in plant nutrient solutions using ion-selective electrodes in hydroponic greenhouse of some vegetables.

    Science.gov (United States)

    Vardar, Gökay; Altıkatoğlu, Melda; Ortaç, Deniz; Cemek, Mustafa; Işıldak, İbrahim

    2015-01-01

    Generally, the life cycle of plants depends on the uptake of essential nutrients in a balanced manner and on toxic elements being under a certain concentration. Lack of control of nutrient levels in nutrient solution can result in reduced plant growth and undesired conditions such as blossom-end rot. In this study, sensitivity and selectivity tests for various polyvinylchloride (PVC)-based ion-selective membranes were conducted to identify those suitable for measuring typical concentration ranges of macronutrients, that is, NO(3-), K(+), and Ca(2+), in hydroponic solutions. The sensitivity and selectivity of PVC-membrane-based ion-selective sensors prepared with tetradodecylammoniumnitrate for NO(3-), valinomycin for K(+), and Ca ionophore IV for Ca(2+) were found to be satisfactory for measuring NO(3-), K(+), and Ca(2+) ions in nutrient solutions over typical ranges of hydroponic concentrations. Potassium, calcium, and nitrate levels that were utilized by cucumber and tomato seedlings in the greenhouse were different. The findings show that tomato plants consumed less amounts of nitrate than cucumber plants over the first 2 months of their growth. We also found that the potassium intake was higher than other nutritional elements tested for all plants. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

  2. Chromatin compaction under mixed salt conditions: opposite effects of sodium and potassium ions on nucleosome array folding.

    Science.gov (United States)

    Allahverdi, Abdollah; Chen, Qinming; Korolev, Nikolay; Nordenskiöld, Lars

    2015-02-17

    It is well known that chromatin structure is highly sensitive to the ionic environment. However, the combined effects of a physiologically relevant mixed ionic environment of K(+), Mg(2+) and Na(+), which are the main cations of the cell cytoplasm, has not been systematically investigated. We studied folding and self-association (aggregation) of recombinant 12-mer nucleosome arrays with 177 bp DNA repeat length in solutions of mixtures of K(+) and Mg(2+) or Na(+) and Mg(2+). In the presence of Mg(2+), the addition of sodium ions promotes folding of array into 30-nm fibres, whereas in mixtures of K(+) and Mg(2+), potassium ions abrogate folding. We found that self-association of nucleosome arrays in mixed salt solutions is synergistically promoted by Mg(2+) and monovalent ions, with sodium being slightly more efficient than potassium in amplifying the self-association. The results highlight the importance of a mixed ionic environment for the compaction of chromatin under physiological conditions and demonstrate the complicated nature of the various factors that determine and regulate chromatin compaction in vivo.

  3. X-ray absorption of the effect of plasticizers on ion-pair dissociation in a poly(ethylene oxide)-potassium salt complex

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.Q.; Lee, H.S.; Hanson, L.K.; McBreen, J. (Brookhaven National Lab., Upton, NY (United States)); Xu, Z.S.; Skotheim, T.A. (Moltech Corp., Stony Brook, NY (United States)); Okamoto, Y. (Polytechnic Univ., Brooklyn, NY (United States)); Lu, F. (Univ. of Kentucky, Lexington, KY (United States))

    1995-01-01

    Polyethylene oxide (PEO)-salt systems are an important new class of electrolytes that are being considered for use in high specific energy rechargeable lithium batteries. Near-edge X-ray absorption fine structure (NEXAFS) spectra, at the potassium K edge, were obtained for a potassium salt in the following systems: (1) a propylene carbonate (PC) solution, (2) a modified carbonate (MC3) solution, and (3) poly(ethylene oxide) (PEO)-potassium salt complexes with either PC or MC3 as a plasticizer. MC3 is a new plasticizer developed in the authors' laboratory which is similar to PC except that, instead of a methyl group, there are three ethylene oxide units attached to the 4-position. By examining the NEXAFS of various potassium salt reference systems, it was found that the white line splitting in the near-edge region was correlated with ion-pairing. The degree of white line splitting was used to study ion-pair dissociation effects of PC and MC3 qualitatively. When used as a solvent, MC3 has a stronger ion-pair dissociation effect compared to PC. When used as a plasticizer in a PEO-potassium salt complex, the enhancement effect on ion-pair dissociation of MC3 is superior to PC. These results were corroborated by Raman spectroscopy which showed that MC3 has a stronger ion-pair dissociation effect than PC.

  4. Construction of waveguiding structures in potassium lithium tantalate niobate crystals by combined laser ablation and ion implantation

    Science.gov (United States)

    Yashar, Ayelet Badichi; Ilan, Harel; Agranat, Aharon J.

    2015-02-01

    A generic methodology for constructing complex integrated electro-optic circuits in waveguided configurations is presented. The method is based on combining two techniques, "laser ablation" and "refractive index engineering by ion implantations." The constructed circuits are side-cladded by air trenches that were produced using laser ablation and bottom-cladded by a layer with a reduced refractive index which is generated through the implantation of He+ ions. This fabrication technique enables the construction of circular structures with complex geometry featuring small radii of curvature, and further can be employed to construct microfluidic channels on the same substrate. The research demonstrates waveguides in both linear and circular configurations that were constructed in a potassium lithium tantalate niobate (KLTN) substrate using the aforementioned method, proving that this substrate is a suitable candidate for use in creating laboratories-on-a-chip with multifunctional capabilities. The proposed techniques used in the research are generic and applicable to a wide range of substrates.

  5. Biology of the KCNQ1 Potassium Channel

    Directory of Open Access Journals (Sweden)

    Geoffrey W. Abbott

    2014-01-01

    Full Text Available Ion channels are essential for basic cellular function and for processes including sensory perception and intercellular communication in multicellular organisms. Voltage-gated potassium (Kv channels facilitate dynamic cellular repolarization during an action potential, opening in response to membrane depolarization to facilitate K+ efflux. In both excitable and nonexcitable cells other, constitutively active, K+ channels provide a relatively constant repolarizing force to control membrane potential, ion homeostasis, and secretory processes. Of the forty known human Kv channel pore-forming α subunits that coassemble in various combinations to form the fundamental tetrameric channel pore and voltage sensor module, KCNQ1 is unique. KCNQ1 stands alone in having the capacity to form either channels that are voltage-dependent and require membrane depolarization for activation, or constitutively active channels. In mammals, KCNQ1 regulates processes including gastric acid secretion, thyroid hormone biosynthesis, salt and glucose homeostasis, and cell volume and in some species is required for rhythmic beating of the heart. In this review, the author discusses the unique functional properties, regulation, cell biology, diverse physiological roles, and involvement in human disease states of this chameleonic K+ channel.

  6. Potassium Secondary Batteries.

    Science.gov (United States)

    Eftekhari, Ali; Jian, Zelang; Ji, Xiulei

    2017-02-08

    Potassium may exhibit advantages over lithium or sodium as a charge carrier in rechargeable batteries. Analogues of Prussian blue can provide millions of cyclic voltammetric cycles in aqueous electrolyte. Potassium intercalation chemistry has recently been demonstrated compatible with both graphite and nongraphitic carbons. In addition to potassium-ion batteries, potassium-O2 (or -air) and potassium-sulfur batteries are emerging. Additionally, aqueous potassium-ion batteries also exhibit high reversibility and long cycling life. Because of potentially low cost, availability of basic materials, and intriguing electrochemical behaviors, this new class of secondary batteries is attracting much attention. This mini-review summarizes the current status, opportunities, and future challenges of potassium secondary batteries.

  7. On the concept of resting potential--pumping ratio of the Na⁺/K⁺ pump and concentration ratios of potassium ions outside and inside the cell to sodium ions inside and outside the cell.

    Science.gov (United States)

    Xu, Ning

    2013-01-01

    In animal cells, the resting potential is established by the concentration gradients of sodium and potassium ions and the different permeabilities of the cell membrane to them. The large concentration gradients of sodium and potassium ions are maintained by the Na⁺/K⁺ pump. Under physiological conditions, the pump transports three sodium ions out of and two potassium ions into the cell per ATP hydrolyzed. However, unlike other primary or secondary active transporters, the Na⁺/K⁺ pump does not work at the equilibrium state, so the pumping ratio is not a thermodynamic property of the pump. In this article, I propose a dipole-charging model of the Na⁺/K⁺ pump to prove that the three Na⁺ to two K⁺ pumping ratio of the Na⁺/K⁺ pump is determined by the ratio of the ionic mobilities of potassium to sodium ions, which is to ensure the time constant τ and the τ-dependent processes, such as the normal working state of the Na⁺/K⁺ pump and the propagation of an action potential. Further, the concentration ratios of potassium ions outside and inside the cell to sodium ions inside and outside the cell are 0.3027 and 0.9788, respectively, and the sum of the potassium and sodium equilibrium potentials is -30.3 mV. A comparative study on these constants is made for some marine, freshwater and terrestrial animals. These findings suggest that the pumping ratio of the Na⁺/K⁺ pump and the ion concentration ratios play a role in the evolution of animal cells.

  8. STUDY OF OPTICAL AND LUMINESCENT PROPERTIES OF POTASSIUM-ALUMINA-BORATE GLASS DOPED WITH Cr3+ IONS

    Directory of Open Access Journals (Sweden)

    A. D. Gorbachev

    2016-01-01

    Full Text Available Potassium-alumina-borate glass doped with chromium ions have been synthesized and investigated, and results are presented. We have synthesized glass of 25K2O-25Al2O3-50B2O3 speciation with addition of 0.2 weight per cent of Cr. It was found out, that heat treatment induces changes in absorption and photoluminescence spectra. According to x-ray diffraction measurements, it has been shown that Al4B2O9 nanocrystalls have been obtained. The average diameter of nanocrystalls is 15 nm. Luminescence spectra have shown that Cr3+ ions are in an octahedral crystalline surrounding of the alumina ions similar to the spectrum of ruby crystal. A conclusion has been done that nanocrystalls of Al4B2O9: Cr3+ are obtained, most probably, in the researched glass. Synthesized material can be used as the base for fiber amplifier in data-transmission systems and as an active substance for medical lasers.

  9. Students' Understanding of External Representations of the Potassium Ion Channel Protein, Part I: Affordances and Limitations of Ribbon Diagrams, Vines, and Hydrophobic/Polar Representations

    Science.gov (United States)

    Harle, Marissa; Towns, Marcy H.

    2012-01-01

    Research on external representations in biochemistry has uncovered student difficulties in comprehending and interpreting external representations. This project focuses on students' understanding of three external representations of the potassium ion channel protein. This is part I of a two-part study, which focuses on the affordances and…

  10. The influence of potassium and calcium ions on nitrogen metabolism of cucumber seedlings

    Directory of Open Access Journals (Sweden)

    Genowefa Kubik-Dobosz

    2014-01-01

    Full Text Available It was found that K+ or Ca2+ deficiency in a nitrate or ammonium medium increased the amount of accumulated total and non-protein nitrogen in some organs of cucumber seedlings, as also caused changes in accumulated potassium and calcium. Lack of K+ or Ca2+ in a medium which did not contain nitrogen led to an increased level of glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase activity in the cotyledons and roots of cucumbers. Similar changes in the activity of these enzymes were noted in certain organs of seedlings growing in nitrate or ammonium medium with decreased K+ or Ca2+ contents, although the magnitude of these changes depended upon the applied dosage of these cations, the form of mineral nitrogen, developmental phase of plants and the plant organ dealt with.

  11. Incorporation of surface plasmon resonance with novel valinomycin doped chitosan-graphene oxide thin film for sensing potassium ion.

    Science.gov (United States)

    Zainudin, Afiq Azri; Fen, Yap Wing; Yusof, Nor Azah; Al-Rekabi, Sura Hmoud; Mahdi, Mohd Adzir; Omar, Nur Alia Sheh

    2018-02-15

    In this study, the combination of novel valinomycin doped chitosan-graphene oxide (C-GO-V) thin film and surface plasmon resonance (SPR) system for potassium ion (K+) detection has been developed. The novel C-GO-V thin film was deposited on the gold surface using spin coating technique. The system was used to monitor SPR signal for K+ in solution with and without C-GO-V thin film. The K+ can be detected by measuring the SPR signal when C-GO-V thin film is exposed to K+ in solution. The sensor produces a linear response for K+ ion up to 100ppm with sensitivity and detection limit of 0.00948°ppm-1 and 0.001ppm, respectively. These results indicate that the C-GO-V film is high potential as a sensor element for K+ that has been proved by the SPR measurement. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Ion channel profile of TRPM8 cold receptors reveals a novel role of TASK-3 potassium channels in thermosensation

    Science.gov (United States)

    Morenilla-Palao, Cruz; Luis, Enoch; Fernández-Peña, Carlos; Quintero, Eva; Weaver, Janelle L.; Bayliss, Douglas A.; Viana, Félix

    2017-01-01

    Summary Animals sense cold ambient temperatures through the activation of peripheral thermoreceptors that express TRPM8, a cold- and menthol-activated ion channel. These receptors can discriminate a very wide range of temperatures from innocuous to noxious. The molecular mechanism responsible for the variable sensitivity of individual cold receptors to temperature is unclear. To address this question, we performed a detailed ion channel expression analysis of cold sensitive neurons, combining BAC transgenesis with a molecular profiling approach in FACS purified TRPM8 neurons. We found that TASK-3 leak potassium channels are highly enriched in a subpopulation of these sensory neurons. The thermal threshold of TRPM8 cold neurons is decreased during TASK-3 blockade and in mice lacking TASK-3 and, most importantly, these mice display hypersensitivity to cold. Our results demonstrate a novel role of TASK-3 channels in thermosensation, showing that a channel-based combinatorial strategy in TRPM8 cold thermoreceptors leads to molecular specialization and functional diversity. PMID:25199828

  13. Superior Potassium Ion Storage via Vertical MoS2 "Nano-Rose" with Expanded Interlayers on Graphene.

    Science.gov (United States)

    Xie, Keyu; Yuan, Kai; Li, Xin; Lu, Wei; Shen, Chao; Liang, Chenglu; Vajtai, Robert; Ajayan, Pulickel; Wei, Bingqing

    2017-11-01

    Potassium has its unique advantages over lithium or sodium as a charge carrier in rechargeable batteries. However, progresses in K-ion battery (KIB) chemistry have so far been hindered by lacking suitable electrode materials to host the relatively large K+ ions compared to its Li+ and Na+ counterparts. Herein, molybdenum disulfide (MoS2 ) "roses" grown on reduced graphene oxide sheets (MoS2 @rGO) are synthesized via a two-step solvothermal route. The as-synthesized MoS2 @rGO composite, with expanded interlayer spacing of MoS2 , chemically bonded between MoS2 and rGO, and a unique nano-architecture, displays the one of the best electrochemical performances to date as an anode material for nonaqueous KIBs. More importantly, a combined K+ storage mechanism of intercalation and conversion reaction is also revealed. The findings presented indicate the enormous potential of layered metal dichalcogenides as advanced electrode materials for high-performance KIBs and also provide new insights and understanding of K+ storage mechanism. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Sputtering of sodium and potassium from nepheline: Secondary ion yields and velocity spectra

    Science.gov (United States)

    Martinez, R.; Langlinay, Th.; Ponciano, C. R.; da Silveira, E. F.; Palumbo, M. E.; Strazzulla, G.; Brucato, J. R.; Hijazi, H.; Agnihotri, A. N.; Boduch, P.; Cassimi, A.; Domaracka, A.; Ropars, F.; Rothard, H.

    2017-09-01

    Silicates are the dominant surface material of many Solar System objects, which are exposed to ion bombardment by solar wind ions and cosmic rays. Induced physico-chemical processes include sputtering which can contribute to the formation of an exosphere. We have measured sputtering yields and velocity spectra of secondary ions ejected from nepheline, an aluminosilicate thought to be a good analogue for Mercury's surface, as a laboratory approach to understand the evolution of silicate surfaces and the presence of Na and K vapor in the exosphere. Experiments were performed with highly charged ion beams (keV/u-MeV/u) delivered by GANIL using an imaging XY-TOF-SIMS device under UHV conditions. The fluence dependence of sputtering yields gives information about the evolution of surface stoichiometry during irradiation. From the energy distributions N(E) of sputtered particles, the fraction of particles which could escape from the gravitational field of Mercury, and of those falling back and possibly contributing to populate the exosphere can be roughly estimated.

  15. X-ray absorption studies of the effect of plasticizers on ion-pair dissociation in a poly(ethylene oxide)-potassium salt complex

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.Q.; Lee, H.S.; McBreen, J. [Brookhaven National Lab., Upton, NY (United States); Xu, Z.S.; Skotheim, T.A. [Moltech Corp., Stony Brook, NY (United States); Okamoto, Y. [Polytechnic Univ., Brooklyn, NY (United States); Lu, F. [Univ. of Kentucky, Lexington, KY (United States)

    1994-12-31

    Polyethylene oxide (PEO)-salt systems are an important new class of electrolytes that are being considered for use in high specific energy rechargeable lithium batteries. Near-edge x-ray absorption fine structure (NEXAFS) spectra, at the potassium K-edge, were obtained for the following systems: a potassium salt in (1) a propylene carbonate (PC) solution, (2) a modified carbonate (MC3) solution and (3) in a poly(ethylene oxide) (PEO)-potassium salt complexes having either PC or MC3 as a plasticizer. MC3 is similar to PC except that, instead of a methyl group, there are three ethylene oxide units attached to the 4-position. The degree of white line splitting was used to study ion pair dissociation effects of PC and MC3 qualitatively. When used as a solvent, MC3 has a stronger ion pair dissociation effect compared to PC. When used as a plasticizer in a PEO-potassium salt complex, the enhancement effect an ion pair dissociation of MC3 is superior to PC. This is in good agreement with temperature conductivity study.

  16. Acepromazine inhibits hERG potassium ion channels expressed in human embryonic kidney 293 cells.

    Science.gov (United States)

    Joo, Young Shin; Lee, Hong Joon; Choi, Jin-Sung; Sung, Ki-Wug

    2017-01-01

    The effects of acepromazine on human ether-à-go-go-related gene (hERG) potassium channels were investigated using whole-cell voltage-clamp technique in human embryonic kidney (HEK293) cells transfected with hERG. The hERG currents were recorded with or without acepromazine, and the steady-state and peak tail currents were analyzed for the evaluating the drug effects. Acepromazine inhibited the hERG currents in a concentration-dependent manner with an IC50 value of 1.5 µM and Hill coefficient of 1.1. Acepromazine blocked hERG currents in a voltage-dependent manner between -40 and +10 mV. Before and after application of acepromazine, the half activation potentials of hERG currents changed to hyperpolarizing direction. Acepromazine blocked both the steady-state hERG currents by depolarizing pulse and the peak tail currents by repolarizing pulse; however, the extent of blocking by acepromazine in the repolarizing pulse was more profound than that in the depolarizing pulse, indicating that acepromazine has a high affinity for the open state of the channels, with a relatively lower affinity for the closed state of hERG channels. A fast application of acepromazine during the tail currents inhibited the open state of hERG channels in a concentration-dependent. The steady-state inactivation of hERG currents shifted to the hyperpolarized direction by acepromazine. These results suggest that acepromazine inhibits the hERG channels probably by an open- and inactivated-channel blocking mechanism. Regarding to the fact that the hERG channels are the potential target of drug-induced long QT syndrome, our results suggest that acepromazine can possibly induce a cardiac arrhythmia through the inhibition of hERG channels.

  17. Maximal Coordinator Number of Potassium, Rubidium, Caesium and Francium Ions in Gaseous Water

    Science.gov (United States)

    Mang, Chao-Yong; Wu, Ke-Chen

    2010-08-01

    To understand the molecular and electronic structure of alkali metal ions, we carry out the MP2 calculation and demonstrate that the maximal coordinator numbers for the hydrated K+ and Rb+ are 8, while those for the hydrated Cs+ and Fr+ are 10. Furthermore, on the basis of the binding energy, the HOMO-LUMO gap and the electron affinity, the stability of the molecular and electronic structures of M+ (H2O)8 (M = K, Rb, Cs, Fr) decreases with the increasing alkali metal atomic number and the stability of the molecular structures of M+ (H2O)8-10 (M = Cs, Fr) decreases with the increasing cluster size.

  18. Altered Potassium Ion Channel Function as a Possible Mechanism of Increased Blood Pressure in Rats Fed Thermally Oxidized Palm Oil Diets.

    Science.gov (United States)

    Nkanu, Etah E; Owu, Daniel U; Osim, Eme E

    2017-12-27

    Intake of thermally oxidized palm oil leads to cytotoxicity and alteration of the potassium ion channel function. This study investigated the effects of fresh and thermally oxidized palm oil diets on blood pressure and potassium ion channel function in blood pressure regulation. Male Wistar rats were randomly divided into three groups of eight rats. Control group received normal feed; fresh palm oil (FPO) and thermally oxidized palm oil (TPO) groups were fed a diet mixed with 15% (weight/weight) fresh palm oil and five times heated palm oil, respectively, for 16 weeks. Blood pressure was measured; blood samples, hearts, and aortas were collected for biochemical and histological analyses. Thermally oxidized palm oil significantly elevated basal mean arterial pressure (MAP). Glibenclamide (10-5 mmol/L) and tetraethylammonium (TEA; 10-3 mmol/L) significantly raised blood pressure in TPO compared with FPO and control groups. Levcromakalim (10-6 mmol/L) significantly (p palm oil increases MAP probably due to the attenuation of adenosine triphosphate-sensitive potassium (KATP) and large-conductance calcium-dependent potassium (BKCa) channels, tissue peroxidation, and altered histological structures of the heart and blood vessels.

  19. Tetrameric DABCO™-Bromine: an Efficient and Versatile Reagent ...

    African Journals Online (AJOL)

    Tetrameric DABCO™-bromine is a powerful brominating agent but shows reasonable selectivity with certain substrates. The selective bromination for activated aromatic compounds and alkenes is reported. Synthesis of -bromo ketones and nitriles has also been achieved by using this reagent and the results are also ...

  20. Removal of Ca(II) and Mg(II) from potassium chromate solution on Amberlite IRC 748 synthetic resin by ion exchange.

    Science.gov (United States)

    Yu, Zhihui; Qi, Tao; Qu, Jingkui; Wang, Lina; Chu, Jinglong

    2009-08-15

    Experimental measurements have been made on the batch ion exchange of Ca(II) and Mg(II) from potassium chromate solution using cation exchanger of Amberlite IRC 748 as K+ form. The ion exchange behavior of two alkaline-earth metals on the resin, depending on contact time, pH, temperature and resin dosage was studied. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms. For Ca(II) ion, the Langmuir model represented the adsorption process better than the Freundlich model. The maximum ion exchange capacity was found to be 47.21 mg g(-1) for Ca(II) and 27.70 mg g(-1) for Mg(II). The kinetic data were tested using Lagergren-first-order and pseudo-second-order kinetic models. Kinetic data correlated well with the pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Various thermodynamic parameters such as Gibbs free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) were also calculated. These parameters showed that the ion exchange of Ca(II) and Mg(II) from potassium chromate solution was feasible, spontaneous and endothermic process in nature. The activation energy of ion-exchange (E(a)) was determined as 12.34 kJ mol(-1) for Ca(II) and 9.865 kJ mol(-1) for Mg(II) according to the Arrhenius equation.

  1. Accumulation and localization of sodium and potassium ions in maize plants on saline soil

    Directory of Open Access Journals (Sweden)

    S. N. Kabuzenko

    2013-02-01

    Full Text Available The goal of this work is studying the accumulation and distribution of Na+ and K+ in maize hybrids of different salt tolerance under conditions of the chloride salinity. The new corn hybrid Veselka MV (salt-tolerant and Odessa 375 MB (not salt-tolerant were studied. The plants grown in salt-free chernozem soil are control. In the experiment, sodium chloride was dissolved in the irrigation water to form the salinity of test soils up to concentrations of 0.25, 0.5, 0.75, and 1.0% of ovendry weight. Soil moisture in the pots was maintained at 60% of the full field water capacity, the air temperature was +25…+27 °C, and the light – 10 klux. Plant samples were dried in the oven under 70 °C. Then, the average sample of 10 specimens was thoroughly levigated in the porcelain pounder  and dispersed in distilled water at 100 °C. The ions were extracted, and the extracts were centrifuged for 20 min at 3000 rpm. The ions content in the cell sap was analysed. Plant samples (1 g were incubated 10 min in chloroform, dried carefully with filter paper, and then the cell sap was squeezed. 1 ml of clear top layer of the cell sap was dissolved in 10 ml of distilled water. Ions content was determined by the atomic absorption spectrophotometer ("Karl Zeiss", Germany. Salt-tolerant maize hybrid Veselka MW (14 days age is characterized by an increased content of Na+ in the root tissues in comparison with the above-ground parts. In Odessa 375 MB hybrid this regularity is less pronounced. With the increase of sodium chloride concentration in the soil the content of Na+ in the aerial parts of plants rises. That may be connected with the reduced role of a root barrier. The salt-tolerant hybrid has a higher content of Na+ in the roots as compared to the above-ground parts. The content of K+ was higher in the above-ground parts, which is more pronounced in the salt-tolerant hybrid Veselka MB. The decrease of K+ in cell sap of the root under saline conditions was

  2. Protein-Coupled Fluorescent Probe To Visualize Potassium Ion Transition on Cellular Membranes.

    Science.gov (United States)

    Hirata, Tomoya; Terai, Takuya; Yamamura, Hisao; Shimonishi, Manabu; Komatsu, Toru; Hanaoka, Kenjiro; Ueno, Tasuku; Imaizumi, Yuji; Nagano, Tetsuo; Urano, Yasuteru

    2016-03-01

    K(+) is the most abundant metal ion in cells, and changes of [K(+)] around cell membranes play important roles in physiological events. However, there is no practical method to selectively visualize [K(+)] at the surface of cells. To address this issue, we have developed a protein-coupled fluorescent probe for K(+), TLSHalo. TLSHalo is responsive to [K(+)] in the physiological range, with good selectivity over Na(+) and retains its K(+)-sensing properties after covalent conjugation with HaloTag protein. By using cells expressing HaloTag on the plasma membrane, we successfully directed TLSHalo specifically to the outer surface of target cells. This enabled us to visualize localized extracellular [K(+)] change with TLSHalo under a fluorescence microscope in real time. To confirm the experimental value of this system, we used TLSHalo to monitor extracellular [K(+)] change induced by K(+) ionophores or by activation of a native Ca(2+)-dependent K(+) channel (BK channel). Further, we show that K(+) efflux via BK channel induced by electrical stimulation at the bottom surface of the cells can be visualized with TLSHalo by means of total internal reflection fluorescence microscope (TIRFM) imaging. Our methodology should be useful to analyze physiological K(+) dynamics with high spatiotemporal resolution.

  3. A study of the effect of lithium oxide on the spectral properties of potassium-aluminoborate glass activated by chromium ions

    Science.gov (United States)

    Babkina, A. N.; Gorbachev, A. D.; Zyryanova, K. S.; Nikonorov, N. V.; Nuryev, R. K.; Stepanov, S. A.

    2017-09-01

    The results of designing and studying of potassium-aluminoborate glass activated by chromium and lithium ions are discussed. Changes in the absorption and luminescence spectra of glass after the isothermal treatment are demonstrated. X-ray diffraction data showed the presence of Li(Al7B4O17) and Cr2O3 nanocrystals with an average size of 20 and 15 nm, respectively. Analysis of the luminescence spectra showed that the Cr3+ ions are in a crystalline environment. The luminescence quantum yield was 20-50%, which indicates the prospects for using such materials as a basis for fiber amplifiers in information transmission systems and laser biomedical technologies.

  4. C-terminal domains implicated in the functional surface expression of potassium channels

    Science.gov (United States)

    Jenke, Marc; Sánchez, Araceli; Monje, Francisco; Stühmer, Walter; Weseloh, Rüdiger M.; Pardo, Luis A.

    2003-01-01

    A short C-terminal domain is required for correct tetrameric assembly in some potassium channels. Here, we show that this domain forms a coiled coil that determines not only the stability but also the selectivity of the multimerization. Synthetic peptides comprising the sequence of this domain in Eag1 and other channels are able to form highly stable tetrameric coiled coils and display selective heteromultimeric interactions. We show that loss of function caused by disruption of this domain in Herg1 can be rescued by introducing the equivalent domain from Eag1, and that this chimeric protein can form heteromultimers with Eag1 while wild-type Erg1 cannot. Additionally, a short endoplasmic reticulum retention sequence closely preceding the coiled coil plays a crucial role for surface expression. Both domains appear to co-operate to form fully functional channels on the cell surface and are a frequent finding in ion channels. Many pathological phenotypes may be attributed to mutations affecting one or both domains. PMID:12554641

  5. Studies on the interaction of growth regulators with potassium ions in some physiological processes in the bean (Phaseolus vulguris L.. II. The effect of potassium on growth of bean leaves and on their potassium and hormone levels

    Directory of Open Access Journals (Sweden)

    Jadwiga Stopińska

    2014-01-01

    Full Text Available The subject of study was the effect of K on the growth of primary and trifoliate leaves of the bean and on their potassium and hormone levels. Bean seedlings were grown in Hoagland's water solution in which the potassium concentrations (K –NO3, were 1 and 3 mM. The increase in the amount of potassium in bean leaves. elicited by increased K concentration in the medium or by partial defoliation. was correlated with a stimulation of growth of these organs and an increase in their H2O content. These effects were connected with an increase in the amount of ABA and bound GA and decrease in the amount of auxins. The effect of potassium on the level of free gibberellins and cytokinins depended on the kind of leaves. In young, i.e. trifoliate leaves_ K was found to have a positive effect on the level of free GA, whereas in older. i.e. primary leaves, this effect concerned the level of cytokinins.

  6. Rearrangement of potassium ions and Kv1.1/Kv1.2 potassium channels in regenerating axons following end-to-end neurorrhaphy: ionic images from TOF-SIMS.

    Science.gov (United States)

    Liu, Chiung-Hui; Chang, Hung-Ming; Wu, Tsung-Huan; Chen, Li-You; Yang, Yin-Shuo; Tseng, To-Jung; Liao, Wen-Chieh

    2017-10-01

    The voltage-gated potassium channels Kv1.1 and Kv1.2 that cluster at juxtaparanodal (JXP) regions are essential in the regulation of nerve excitability and play a critical role in axonal conduction. When demyelination occurs, Kv1.1/Kv1.2 activity increases, suppressing the membrane potential nearly to the equilibrium potential of K+, which results in an axonal conduction blockade. The recovery of K+-dependent communication signals and proper clustering of Kv1.1/Kv1.2 channels at JXP regions may directly reflect nerve regeneration following peripheral nerve injury. However, little is known about potassium channel expression and its relationship with the dynamic potassium ion distribution at the node of Ranvier during the regenerative process of peripheral nerve injury (PNI). In the present study, end-to-end neurorrhaphy (EEN) was performed using an in vivo model of PNI. The distribution of K+ at regenerating axons following EEN was detected by time-of-flight secondary-ion mass spectrometry. The specific localization and expression of Kv1.1/Kv1.2 channels were examined by confocal microscopy and western blotting. Our data showed that the re-establishment of K+ distribution and intensity was correlated with the functional recovery of compound muscle action potential morphology in EEN rats. Furthermore, the re-clustering of Kv1.1/1.2 channels 1 and 3 months after EEN at the nodal region of the regenerating nerve corresponded to changes in the K+ distribution. This study provided direct evidence of K+ distribution in regenerating axons for the first time. We proposed that the Kv1.1/Kv1.2 channels re-clustered at the JXP regions of regenerating axons are essential for modulating the proper patterns of K+ distribution in axons for maintaining membrane potential stability after EEN.

  7. Interrupting the flux of delocalized electrons on a dibenzo-18-crown-6-embedded graphite sheet and its relative counteraction in the presence of potassium ions.

    Science.gov (United States)

    Shamsipur, Mojtaba; Taherpour, Avat Arman; Pashabadi, Afshin

    2016-06-20

    Delocalized electrons are free to move throughout a graphite sheet. Based on the interruption of this flux, a new strategy has been developed to establish a highly sensitive impedimetric sensing device for K(+) ions. Here, we report on the successful application of a simple graphite paste incorporated into dibenzo-18-crown-6 (DB18C6), which effectively impedes the electron flux on the graphite sheet. Most importantly, this interruption can be selectively obviated in the presence of potassium ion. Our quantum mechanics-density functional theory (QM-DFT) calculations revealed that, among the possible surface-configurations of the ligand on the graphite surface, the "distorted concave" form is a more energy-favorable configuration and existed in a higher probability. This form is capable of impeding the passage of delocalized electrons over the graphite sheets. From modeling of the detecting processes, the surface configuration of DB18C6 in treating with K(+) was intensely changed to "convex", which facilitates the passage of electrons along the graphite sheet. Optimizations of the structures of DB18C6 and its 1 : 1 and 2 : 1 complexes with potassium ion were also performed using QM-DFT calculations. On the other hand, the modeling of the graphene sheet was performed using the molecular mechanics MMFF94 method, which was used to model the detecting process. The proposed sensor was found to quantify the potassium ion by faradaic impedance spectroscopy in the range of 50 to 1500 pM with a detection limit of 35 pM.

  8. Removal of Ca(II) and Mg(II) from potassium chromate solution on Amberlite IRC 748 synthetic resin by ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Yu Zhihui [Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Qi Tao, E-mail: tqgreen@home.ipe.ac.cn [Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Qu Jingkui; Wang Lina; Chu Jinglong [Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2009-08-15

    Experimental measurements have been made on the batch ion exchange of Ca(II) and Mg(II) from potassium chromate solution using cation exchanger of Amberlite IRC 748 as K{sup +} form. The ion exchange behavior of two alkaline-earth metals on the resin, depending on contact time, pH, temperature and resin dosage was studied. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms. For Ca(II) ion, the Langmuir model represented the adsorption process better than the Freundlich model. The maximum ion exchange capacity was found to be 47.21 mg g{sup -1} for Ca(II) and 27.70 mg g{sup -1} for Mg(II). The kinetic data were tested using Lagergren-first-order and pseudo-second-order kinetic models. Kinetic data correlated well with the pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Various thermodynamic parameters such as Gibbs free energy ({Delta}G{sup o}), enthalpy ({Delta}H{sup o}) and entropy ({Delta}S{sup o}) were also calculated. These parameters showed that the ion exchange of Ca(II) and Mg(II) from potassium chromate solution was feasible, spontaneous and endothermic process in nature. The activation energy of ion-exchange (E{sub a}) was determined as 12.34 kJ mol{sup -1} for Ca(II) and 9.865 kJ mol{sup -1} for Mg(II) according to the Arrhenius equation.

  9. Nitrated poly(4-hydroxystyrene) microspheres for optical pH and potassium ion sensing based on turbidity changes accompanying polymer sweller

    Science.gov (United States)

    Wang, Hongming

    2000-10-01

    Porous poly(4-acetoxystyrene) swellable microspheres with diameters approximately 1~2 μm were prepared by seeded emulsion polymerization. Toluene was used as the porogenic solvent and divinylbenzene was used as the crosslinker. The seed particles with diameters approximately 0.5~1 μm were prepared by dispersion polymerization without adding porogenic solvent and crosslinker. Functionality was introduced by two derivatization reactions, hydrolysis and nitration, to form nitrated poly(4-hydroxystyrene). These polymer microspheres swell at high pH due to the deprotonation of the hydroxyl group on the polymer backbone. Swelling is accompanied by an increase in water content which causes the polymer refractive index to decrease. These microspheres, were embedded in a hydrogel for pH sensing. When either dibenzo-18-crown-6 or valinomycin was co- immobilized on the polymer, they were then used to sense potassium ion. Poly(2-hydroxyethylmethacrylate) or poly(vinylalcohol) hydrogel membranes with embedded nitrated poly(4- hydroxystyrene) microspheres were prepared by photopolymerization. These membranes possess desirable optical properties for pH sensing. The refractive index of the hydrated hydrogel is constant and not affected by pH, but the refractive index of the microspheres does vary with pH. When the membrane is in contact with a buffer at high pH, the membrane turbidity decreases because the refractive index difference between the microspheres and the hydrogel decreases. The apparent pKa values can be adjusted by varying the nitrogen percentage of the microspheres, by controlling the conditions of the nitration reaction. The observed pK a value can be as low as 5.6 or as high as 10.2. The response time of the membrane with microspheres prepared by seeded emulsion polymerization utilizing PVA as the membrane matrix was 10~15 seconds. Response times were longer for the poly(HEMA) matrix with embedded microspheres synthesized by dispersion polymerization. A very

  10. Simultaneous determination of chloride and potassium in carbohydrate electrolyte beverages using an array of ion-selective electrodes controlled by a microcomputer

    Directory of Open Access Journals (Sweden)

    Fernandes Julio Cesar B.

    2000-01-01

    Full Text Available This work describes the building of a potentiometric system composed of an array of ion-selective electrodes and controlled by microcomputer. The system employed an acquisition card model ACL-8111 from ADLink Technology for the selection control of the ion-selective electrodes through an analogic switch (ADG201 with simultaneous data acquisition. Software implemented on the VISUAL BASIC 4.0 language was employed for electrode control and data acquisition. This system was evaluated in the simultaneous determination of chloride and potassium in samples of carbohydrate-electrolyte beverages. The results obtained for these determinations were in agreement with those obtained by the reference method taking into account the estimated error in the determinations.

  11. Structure of a tetrameric galectin from Cinachyrella sp. (ball sponge)

    Energy Technology Data Exchange (ETDEWEB)

    Freymann, Douglas M., E-mail: freymann@northwestern.edu [Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611 (United States); Nakamura, Yuka [Hokkaido University, 3-1-1 Minato-cho, Hakodate 041-8611 (Japan); Focia, Pamela J. [Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611 (United States); Sakai, Ryuichi [Hokkaido University, 3-1-1 Minato-cho, Hakodate 041-8611 (Japan); Swanson, Geoffrey T. [Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611 (United States)

    2012-09-01

    The structure of a tetrameric sponge galectin suggests a basis for glutamate receptor potentiation. The galectins are a family of proteins that bind with highest affinity to N-acetyllactosamine disaccharides, which are common constituents of asparagine-linked complex glycans. They play important and diverse physiological roles, particularly in the immune system, and are thought to be critical metastatic agents for many types of cancer cells, including gliomas. A recent bioactivity-based screen of marine sponge (Cinachyrella sp.) extract identified an ancestral member of the galectin family based on its unexpected ability to positively modulate mammalian ionotropic glutamate receptor function. To gain insight into the mechanistic basis of this activity, the 2.1 Å resolution X-ray structure of one member of the family, galectin CchG-1, is reported. While the protomer exhibited structural similarity to mammalian prototype galectin, CchG-1 adopts a novel tetrameric arrangement in which a rigid toroidal-shaped ‘donut’ is stabilized in part by the packing of pairs of vicinal disulfide bonds. Twofold symmetry between binding-site pairs provides a basis for a model for interaction with ionotropic glutamate receptors.

  12. Emerging Role of Calcium-Activated Potassium Channel in the Regulation of Cell Viability Following Potassium Ions Challenge in HEK293 Cells and Pharmacological Modulation

    Science.gov (United States)

    Tricarico, Domenico; Mele, Antonietta; Calzolaro, Sara; Cannone, Gianluigi; Camerino, Giulia Maria; Dinardo, Maria Maddalena; Latorre, Ramon; Conte Camerino, Diana

    2013-01-01

    proliferation induced by hyperkalemia. These findings may have relevance in disorders associated with abnormal K+ ion homeostasis including periodic paralysis and myotonia. PMID:23874973

  13. Effects of fluoxetine on protein expression of potassium ion channels in the brain of chronic mild stress rats

    Directory of Open Access Journals (Sweden)

    Chunlin Chen

    2015-01-01

    Full Text Available The purpose of this study is to investigate the expression of major potassium channel subtypes in the brain of chronical mild stress (CMS rats and reveal the effects of fluoxetine on the expression of these channels. Rats were exposed to a variety of unpredictable stress for three weeks and induced anhedonia, lower sucrose preference, locomotor activity and lower body weight. The protein expressions were determined by Western blot. CMS significantly increased the expression of Kv2.1 channel in frontal cortex but not in hippocampus, and the expression level was normalized after fluoxetine treatment. The expression of TREK-1 channel was also obviously increased in frontal cortex in CMS rats. Fluoxetine treatment might prevent this increase. However, the expression of Kv3.1 and Kv4.2 channels was considerably decreased in hippocampus after CMS, and was not affected by fluoxetine. These results suggest that different subtypes of potassium channels are associated with the pathophysiology of depression and that the therapeutical effects of fluoxetine may relate to Kv2.1 and TREK-1 potassium channels.

  14. Stimulation by potassium ions of the growth of Rhizopus oligosporus during liquid-and solid-substrate fermentations.

    Science.gov (United States)

    Peñaloza, W; Davey, C L; Hedger, J N; Kell, D B

    1991-03-01

    Soya beans and several other beans and cereals have been used as substrates for tempe fermentation with the fungus Rhizopus oligosporus Saito. Except for the presence of alkaloids, the chemical composition of lupins (Lupinus mutabilis Sweet) is similar to that of soya beans. Therefore the potential of lupins for tempe production in regions with a long tradition of lupin consumption is promising. The preparation of the fermentation substrate when using bitter lupins (which contain significan quantities of alkaloids) as starting material includes a debittering stage to remove the alkaloids. However, we found that the debittering process yielded lupins that did not support the mycelial growth required in the tempe fermentation. We discovered that potassium is preferentially leached out during the debittering process. The effect of potassium on fungal biomass formation was monitored using a computerized system that determines biomass accretion by measurement of the electrical capacitance at radio frequencies. The importance of potassium for the growth of R. oligosporus was confirmed in liquid cultures. A linear relationship was found between biomass yield and K(+) concentration in the range of 1 to 10 mg/l. The present report represents one of the few demonstrations of a mineral deficiency during the growth of a fungus on a natural, solid substrate.

  15. Inorganic ion exchangers based on manganese and potassium for recovery and removal of pollutant metals of aqueous effluents; Trocadores ionicos inorganicos a base de manganes e potassio para recuperacao e remocao de metais poluentes de efluentes aquosos

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Jacinete Lima dos

    2001-07-01

    This work presents a study on the synthesis, characterization and ion exchange properties of inorganic ion exchangers based on manganese and potassium. The ion exchangers were synthesized by calcination of the mixture of manganese(II) oxalate and potassium oxalate and were characterized by granulometer distribution analysis, X-ray powder diffraction, infrared spectroscopy and scanning electron microscopic. From the data obtained in characterization it was observed that exist two distinguished groups of these materials. The first group belong to ion exchangers with up to 30% w/w potassium and the second group formed by the ion exchangers with more than 30% w / w of content of potassium in their compositions. The studies of adsorption of these materials showed that the adsorption of Cd{sup 2+} is a function of the following parameters as pH, concentration of Cd{sup 2+}, time of contact between the ion exchangers the concentration of the Cd{sup 2+} solution and the interference of other ions like Ni{sup 2+}. The great pH of adsorption for these materials occur in pH 9, the study of the influence of the cadmium concentration in the adsorption showed that for a group of exchangers the adsorption decreases with the increase of cadmium concentration and for the other group the adsorption increases with the increase of cadmium concentration. The kinetics of adsorption occur in a contact time between the ion exchangers and the Cd{sup 2+} solutions relatively short, at about 15 minutes is necessary to establish the equilibrium. The presence of Ni{sup 2+} as interfering ion decreases the adsorption of cadmium of 99,7% to 65%. These inorganic ion exchangers showed be good exchangers for Cd{sup 2+}. (author)

  16. High index contrast potassium double tungstate waveguides towards efficient rare-earth ion amplification on-chip

    NARCIS (Netherlands)

    Sefünç, Mustafa; Segerink, Franciscus B.; García Blanco, Sonia Maria

    2015-01-01

    Rare-earth ion doped KY(WO4)2 amplifiers are proposed to be a good candidate for many future applications by benefiting from the excellent gain characteristics of rare-earth ions, namely high bit rate amplification (

  17. Molecular analysis of potassium ion channel genes in sudden death cases among patients administered psychotropic drug therapy: are polymorphisms in LQT genes a potential risk factor?

    Science.gov (United States)

    Kamei, Sayako; Sato, Noriko; Harayama, Yuta; Nunotani, Miyako; Takatsu, Kanae; Shiozaki, Tetsuya; Hayashi, Tokutaro; Asamura, Hideki

    2014-02-01

    Psychotropic drugs can pose the risk of acquired long QT syndrome (LQTS). Unexpected autopsy-negative sudden death in patients taking psychotropic drugs may be associated with prolonged QT intervals and life-threatening arrhythmias. We analyzed genes that encode for cardiac ion channels and potentially associated with LQTS, examining specifically the potassium channel genes KCNQ1 and KCNH2 in 10 cases of sudden death involving patients administered psychotropic medication in which autopsy findings identified no clear cause of death. We amplified and sequenced all exons of KCNQ1 and KCNH2, identifying G643S, missense polymorphism in KCNQ1, in 6 of the 10 cases. A study analysis indicated that only 11% of 381 healthy Japanese individuals carry this polymorphism. Reports of previous functional analyses indicate that the G643S polymorphism in the KCNQ1 potassium channel protein causes mild I(Ks) channel dysfunction. Our present study suggests that administering psychotropic drug therapy to individuals carrying the G643S polymorphism may heighten the risk of prolonged QT intervals and life-threatening arrhythmias. Thus, screening for the G643S polymorphism before prescribing psychotropic drugs may help reduce the risk of unexpected sudden death.

  18. pH-Dependent Tetramerization and Amantadine Binding of the Transmembrane Helix of M2 from the Influenza A Virus†

    Science.gov (United States)

    Salom, David; Hill, Blake R.; Lear, James D.

    2011-01-01

    The M2 proton channel from the influenza A virus is a small protein with a single transmembrane helix that associates to form a tetramer in vivo. This protein forms proton-selective ion channels, which are the target of the drug amantadine. Here, we propose a mechanism for the pH-dependent association, and amantadine binding of M2, based on studies of a peptide representing the M2 transmembrane segment in dodecylphosphocholine micelles. Using analytical ultracentrifugation, we find that the sedimentation curves for the peptide depend on its concentration in the micellar phase. The data are well-described by a monomer–tetramer equilibrium, and the binding of amantadine shifts the monomer–tetramer equilibrium toward tetrameric species. Both tetramerization and the binding of amantadine lead to increases in the magnitude of the ellipticity at 223 nm in the circular dichroism spectrum of the peptide. The tetramerization and binding of amantadine are more favorable at elevated pH, with a pKa that is assigned to a His side chain, the only ionizable residue within the transmembrane helix. Our results, interpreted quantitatively in terms of a reversible monomer and tetramer protonation equilibrium model, suggest that amantadine competes with protons for binding to the deprotonated tetramer, thereby stabilizing the tetramer in a slightly altered conformation. This model accounts for the observed inhibition of proton flux by amantadine. Additionally, our measurements suggest that the M2 tetramer is substantially protonated at neutral pH and that both singly and doubly protonated states could be involved in M2’s proton conduction at more acidic pHs. PMID:11087364

  19. [Unification of methods for determining the trace quantities of lead, zinc, sodium and potassium ions in the assessment of drinking water adn transfusion fluid quality].

    Science.gov (United States)

    Popkov, V A; Golovina, N V; Evgrafov, A A

    2001-01-01

    The results of long-term studies made by the Department of General Chemistry, I. M. Sechenov Moscow Medical Academy, that deals with unification of methods for determining some ions of metals (lead, zinc, sodium, and potassium) in the assessment of the quality of drinking water and transfusion fluids are summarized. A procedure was developed to determine the trace impurities of zinc, lead, and silver by atomic absorption spectrometry (AAS) by using sorption concentration. C-80-2-aminothiazole, a new sorbent synthesized at the Research Institute of Polymers, was used to detect these ions in the drinking water. With regards to the chosen optimal conditions, drinking water samples were analyzed via their direct spraying in the air-acetylene flame. The prior sorption concentration determined drinking water zinc and lead ions in the concentrations equal to or less than their permissible dose concentrations. The studies indicated that the used methods to determine the trace quantities of metals in the drinking water and aqueous solutions show a high sensitivity, rapidity, simplicity of sample preparation.

  20. A naturally occurring omega current in a Kv3 family potassium channel from a platyhelminth

    Directory of Open Access Journals (Sweden)

    Spencer Andrew N

    2008-06-01

    Full Text Available Abstract Background Voltage-gated ion channels are membrane proteins containing a selective pore that allows permeable ions to transit the membrane in response to a change in the transmembrane voltage. The typical selectivity filter in potassium channels is formed by a tetrameric arrangement of the carbonyl groups of the conserved amino-acid sequence Gly-Tyr-Gly. This canonical pore is opened or closed by conformational changes that originate in the voltage sensor (S4, a transmembrane helix with a series of positively charged amino acids. This sensor moves through a gating pore formed by elements of the S1, S2 and S3 helices, across the plane of the membrane, without allowing ions to pass through the membrane at that site. Recently, synthetic mutagenesis studies in the Drosophila melanogaster Shaker channel and analysis of human disease-causing mutations in sodium channels have identified amino acid residues that are integral parts of the gating-pore; when these residues are mutated the proteins allow a non-specific cation current, known as the omega current, to pass through the gating-pore with relatively low selectivity. Results The N.at-Kv3.2 potassium channel has an unusual weak inward rectifier phenotype. Several mutations of two amino acids in the voltage sensing (S4 transmembrane helix change the phenotype to a typical delayed rectifier. The inward rectifier channels (wild-type and mutant are sensitive to 4-aminopyridine (4-AP but not tetra-ethyl ammonium (TEA, whereas the delayed rectifier mutants are sensitive to TEA but not 4-AP. The inward rectifier channels also manifest low cation selectivity. The relative selectivity for different cations is sensitive to specific mutations in the S4 helix, Conclusion N.at-Kv3.2, a naturally occurring potassium channel of the Kv3 sequence family, mediates ion permeation through a modified gating pore, not the canonical, highly selective pore typical of potassium channels. This channel has evolved to

  1. Gill (Na+,K+)-ATPase from the blue crab Callinectes danae: modulation of K+-phosphatase activity by potassium and ammonium ions.

    Science.gov (United States)

    Masui, D C; Furriel, R P M; Mantelatto, F L M; McNamara, J C; Leone, F A

    2003-04-01

    The kinetic properties of a microsomal gill (Na(+),K(+))-ATPase from the blue crab Callinectes danae were analyzed using the substrate p-nitrophenylphosphate. The (Na(+),K(+))-ATPase hydrolyzed PNPP obeying cooperative kinetics (n=1.5) at a rate of V=125.4+/-7.5 U mg(-1) with K(0.5)=1.2+/-0.1 mmol l(-1); stimulation by potassium (V=121.0+/-6.1 U mg(-1); K(0.5)=2.1+/-0.1 mmol l(-1)) and magnesium ions (V=125.3+/-6.3 U mg(-1); K(0.5)=1.0+/-0.1 mmol l(-1)) was cooperative. Ammonium ions also stimulated the enzyme through site-site interactions (n(H)=2.7) to a rate of V=126.1+/-4.8 U mg(-1) with K(0.5)=13.7+/-0.5 mmol l(-1). However, K(+)-phosphatase activity was not stimulated further by K(+) plus NH(4)(+) ions. Sodium ions (K(I)=36.7+/-1.7 mmol l(-1)), ouabain (K(I)=830.3+/-42.5 micromol l(-1)) and orthovanadate (K(I)=34.0+/-1.4 nmol l(-1)) completely inhibited K(+)-phosphatase activity. The competitive inhibition by ATP (K(I)=57.2+/-2.6 micromol l(-1)) of PNPPase activity suggests that both substrates are hydrolyzed at the same site on the enzyme. These data reveal that the K(+)-phosphatase activity corresponds strictly to a (Na(+),K(+))-ATPase in C. danae gill tissue. This is the first known kinetic characterization of K(+)-phosphatase activity in the portunid crab C. danae and should provide a useful tool for comparative studies.

  2. Novel class III phosphoribosyl diphosphate synthase: structure and properties of the tetrameric, phosphate-activated, non-allosterically inhibited enzyme from Methanocaldococcus jannaschii

    DEFF Research Database (Denmark)

    Kadziola, Anders; Jepsen, Clemens H; Johansson, Eva

    2005-01-01

    , and the crystal structure determined. The enzyme is activated by phosphate ions and only ATP or dATP serve as diphosphoryl donors. The K(m) values are determined as 2.6 mM and 2.8 mM for ATP and ribose 5-phosphate, respectively, and the V(max) value as 2.20 mmol (minxmg of protein)(-1). ADP is a potent inhibitor....... The properties of M.jannaschii PRPP synthase differ widely from previously characterised PRPP synthases by its tetrameric quaternary structure and the simultaneous phosphate ion-activation and lack of allosteric inhibition, and, thus, constitute a novel class of PRPP synthases....

  3. Angiotensin II modulates mouse skeletal muscle resting conductance to chloride and potassium ions and calcium homeostasis via the AT1 receptor and NADPH oxidase.

    Science.gov (United States)

    Cozzoli, Anna; Liantonio, Antonella; Conte, Elena; Cannone, Maria; Massari, Ada Maria; Giustino, Arcangela; Scaramuzzi, Antonia; Pierno, Sabata; Mantuano, Paola; Capogrosso, Roberta Francesca; Camerino, Giulia Maria; De Luca, Annamaria

    2014-10-01

    Angiotensin II (ANG II) plays a role in muscle wasting and remodeling; however, little evidence shows its direct effects on specific muscle functions. We presently investigated the acute in vitro effects of ANG II on resting ionic conductance and calcium homeostasis of mouse extensor digitorum longus (EDL) muscle fibers, based on previous findings that in vivo inhibition of ANG II counteracts the impairment of macroscopic ClC-1 chloride channel conductance (gCl) in the mdx mouse model of muscular dystrophy. By means of intracellular microelectrode recordings we found that ANG II reduced gCl in the nanomolar range and in a concentration-dependent manner (EC50 = 0.06 μM) meanwhile increasing potassium conductance (gK). Both effects were inhibited by the ANG II receptors type 1 (AT1)-receptor antagonist losartan and the protein kinase C inhibitor chelerythrine; no antagonism was observed with the AT2 antagonist PD123,319. The scavenger of reactive oxygen species (ROS) N-acetyl cysteine and the NADPH-oxidase (NOX) inhibitor apocynin also antagonized ANG II effects on resting ionic conductances; the ANG II-dependent gK increase was blocked by iberiotoxin, an inhibitor of calcium-activated potassium channels. ANG II also lowered the threshold for myofiber and muscle contraction. Both ANG II and the AT1 agonist L162,313 increased the intracellular calcium transients, measured by fura-2, with a two-step pattern. These latter effects were not observed in the presence of losartan and of the phospholipase C inhibitor U73122 and the in absence of extracellular calcium, disclosing a Gq-mediated calcium entry mechanism. The data show for the first time that the AT1-mediated ANG II pathway, also involving NOX and ROS, directly modulates ion channels and calcium homeostasis in adult myofibers. Copyright © 2014 the American Physiological Society.

  4. Purification and structural study of the voltage-sensor domain of the human KCNQ1 potassium ion channel.

    Science.gov (United States)

    Peng, Dungeng; Kim, Ji-Hun; Kroncke, Brett M; Law, Cheryl L; Xia, Yan; Droege, Kristin D; Van Horn, Wade D; Vanoye, Carlos G; Sanders, Charles R

    2014-04-01

    KCNQ1 (also known as KV7.1 or KVLQT1) is a voltage-gated potassium channel modulated by members of the KCNE protein family. Among multiple functions, KCNQ1 plays a critical role in the cardiac action potential. This channel is also subject to inherited mutations that cause certain cardiac arrhythmias and deafness. In this study, we report the overexpression, purification, and preliminary structural characterization of the voltage-sensor domain (VSD) of human KCNQ1 (Q1-VSD). Q1-VSD was expressed in Escherichia coli and purified into lyso-palmitoylphosphatidylglycerol micelles, conditions under which this tetraspan membrane protein yields excellent nuclear magnetic resonance (NMR) spectra. NMR studies reveal that Q1-VSD shares a common overall topology with other channel VSDs, with an S0 helix followed by transmembrane helices S1-S4. The exact sequential locations of the helical spans do, however, show significant variations from those of the homologous segments of previously characterized VSDs. The S4 segment of Q1-VSD was seen to be α-helical (with no 310 component) and underwent rapid backbone amide H-D exchange over most of its length. These results lay the foundation for more advanced structural studies and can be used to generate testable hypotheses for future structure-function experiments.

  5. Potassium test

    Science.gov (United States)

    ... also be done if your provider suspects metabolic acidosis (for example, caused by uncontrolled diabetes) or alkalosis ( ... Hypoaldosteronism (very rare) Kidney failure Metabolic or respiratory acidosis Red blood cell destruction Too much potassium in ...

  6. Trimeric and Tetrameric Electron-Deficient Porphyrin Tapes.

    Science.gov (United States)

    Mori, Hirotaka; Kim, Taeyeon; Kim, Dongho; Osuka, Atsuhiro

    2016-05-06

    New hybrid porphyrin tapes comprising meso-3,5-di-tert-butylphenyl-substituted Zn(II) -porphyrins (D) and meso-pentafluorophenyl-substituted Zn(II) -porphyrins (A) were synthesized via cross-condensation of meso-formyl porphyrins 1, 5, and 9 with oligopyrromethanes 2 and 6 as key steps. These hybrid tapes exhibit improved solubilities and enhanced chemical stability as compared with original Dn porphyrin tapes, and all display remarkably coplanar structures favorable for π-conjugation. The absorption spectrum of ADDA displays Q-like bands at 1400 and 1657 nm with a vibronic structure characteristic of porphyrinoids. The cyclic voltammograms exhibited positively shifted oxidation and reduction waves in the order of DDDTetrameric tape ADDA displays five reversible waves in a narrow range of 1.13 V. Two-photon absorption (TPA) measurement confirmed that the π-conjugation path is extended from 12 to ADDA and the molecular polarizability of ADA is larger than that of AAA. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. A novel tetrameric PilZ domain structure from xanthomonads.

    Directory of Open Access Journals (Sweden)

    Tso-Ning Li

    Full Text Available PilZ domain is one of the key receptors for the newly discovered secondary messenger molecule cyclic di-GMP (c-di-GMP. To date, several monomeric PilZ domain proteins have been identified. Some exhibit strong c-di-GMP binding activity, while others have barely detectable c-di-GMP binding activity and require an accessory protein such as FimX to indirectly respond to the c-di-GMP signal. We now report a novel tetrameric PilZ domain structure of XCC6012 from the plant pathogen Xanthomonas campestris pv. campestris (Xcc. It is one of the four PilZ domain proteins essential for Xcc pathogenicity. Although the monomer adopts a structure similar to those of the PilZ domains with very weak c-di-GMP binding activity, it is nevertheless interrupted in the middle by two extra long helices. Four XCC6012 proteins are thus self-assembled into a tetramer via the extra heptad repeat α3 helices to form a parallel four-stranded coiled-coil, which is further enclosed by two sets of inclined α2 and α4 helices. We further generated a series of XCC6012 variants and measured the unfolding temperatures and oligomeric states in order to investigate the nature of this novel tetramer. Discovery of this new PilZ domain architecture increases the complexity of c-di-GMP-mediated regulation.

  8. Trichomonas vaginalis induces IL-1β production in a human prostate epithelial cell line by activating the NLRP3 inflammasome via reactive oxygen species and potassium ion efflux.

    Science.gov (United States)

    Gu, Na-Yeong; Kim, Jung-Hyun; Han, Ik-Hwan; Im, Su-Jeong; Seo, Min-Young; Chung, Yong-Hoon; Ryu, Jae-Sook

    2016-07-01

    Trichomonas vaginalis is a sexually transmitted protozoan parasite that causes vaginitis in women, and urethritis and prostatitis in men. IL-1β is synthesized as immature pro-IL-1β, which is cleaved by activated caspase-1. Caspase-1 is, in turn, activated by a multi-protein complex known as an inflammasome. In this study, we investigated the inflammatory response of a prostate epithelial cell line (RWPE-1) to T. vaginalis and, specifically, the capacity of T. vaginalis to activate the NLRP3 inflammasome. RWPE-1 cells were stimulated by live T. vaginalis, and subsequent expression of pro-IL-1β, IL-1β, NLRP3, ASC and caspase-1 was determined by real-time PCR and Western blotting. IL-1β and caspase-1 production was also measured by ELISA. To evaluate the effects of NLRP3 and caspase-1 on IL-1β production, the activated RWPE-1 cells were transfected with small interfering RNAs to silence the NLRP3 and caspase-1 genes. Activation of the NLRP3 inflammasome was observed by fluorescence microscopy. Intracellular reactive oxygen species (ROS) were evaluated by spectrofluorometry. When RWPE-1 cells were stimulated with live T. vaginalis, the mRNA and protein expression of IL-1β, NLRP3, ASC, and caspase-1 increased. Moreover, silencing of NLRP3 and caspase-1 attenuated T. vaginalis-induced IL-1β secretion. The NADPH oxidase inhibitor DPI and high extracellular potassium ion suppressed the production of IL-1β, caspase-1, and the expression of NLRP3 and ASC proteins. The specific NF-κB inhibitor, Bay 11-7082, inhibited IL-1β production, and also inhibited the production of caspase-1, ASC and NLRP3 proteins. T. vaginalis induces the formation of the NLRP3 inflammasome in human prostate epithelial cells via ROS and potassium ion efflux, and this results in IL-1β production. This is the first evidence for activation of the NLRP3 inflammasome in the inflammatory response by prostate epithelial cells infected with T. vaginalis. Prostate 76:885-896, 2016. © 2016 Wiley

  9. Development of models of active ion transport for whole-cell modelling: cardiac sodium-potassium pump as a case study.

    Science.gov (United States)

    Smith, N P; Crampin, E J

    2004-01-01

    This study presents a method for the reduction of biophysically-based kinetic models for the active transport of ions. A lumping scheme is presented which exploits the differences in timescales associated with fast and slow transitions between model states, while maintaining the thermodynamic properties of the model. The goal of this approach is to contribute to modelling of the effects of disturbances to metabolism, associated with ischaemic heart disease, on cardiac cell function. The approach is illustrated for the sodium-potassium pump in the myocyte. The lumping scheme is applied to produce a 4-state representation from the detailed 15-state model of Läuger and Apell, Eur. Biophys. J. 13 (1986) 309, for which the principles of free energy transduction are used to link the free energy released from ATP hydrolysis (deltaGATP) to the transition rates between states of the model. An iterative minimisation algorithm is implemented to determine the transition rate parameters based on the model fit to experimental data. Finally, the relationship between deltaGATP and pump cycling direction is investigated and compared with recent experimental findings. Copyright 2004 Elsevier Ltd.

  10. A De Novo Mutation in the Sodium-Activated Potassium Channel KCNT2 Alters Ion Selectivity and Causes Epileptic Encephalopathy

    Directory of Open Access Journals (Sweden)

    Sushmitha Gururaj

    2017-10-01

    Full Text Available Early infantile epileptic encephalopathies (EOEE are a debilitating spectrum of disorders associated with cognitive impairments. We present a clinical report of a KCNT2 mutation in an EOEE patient. The de novo heterozygous variant Phe240Leu SLICK was identified by exome sequencing and confirmed by Sanger sequencing. Phe240Leu rSlick and hSLICK channels were electrophysiologically, heterologously characterized to reveal three significant alterations to channel function. First, [Cl−]i sensitivity was reversed in Phe240Leu channels. Second, predominantly K+-selective WT channels were made to favor Na+ over K+ by Phe240Leu. Third, and consequent to altered ion selectivity, Phe240Leu channels had larger inward conductance. Further, rSlick channels induced membrane hyperexcitability when expressed in primary neurons, resembling the cellular seizure phenotype. Taken together, our results confirm that Phe240Leu is a “change-of-function” KCNT2 mutation, demonstrating unusual altered selectivity in KNa channels. These findings establish pathogenicity of the Phe240Leu KCNT2 mutation in the reported EOEE patient.

  11. Characterization and evolution of tetrameric photosystem I from the thermophilic cyanobacterium Chroococcidiopsis sp TS-821.

    Science.gov (United States)

    Li, Meng; Semchonok, Dmitry A; Boekema, Egbert J; Bruce, Barry D

    2014-03-01

    Photosystem I (PSI) is a reaction center associated with oxygenic photosynthesis. Unlike the monomeric reaction centers in green and purple bacteria, PSI forms trimeric complexes in most cyanobacteria with a 3-fold rotational symmetry that is primarily stabilized via adjacent PsaL subunits; however, in plants/algae, PSI is monomeric. In this study, we discovered a tetrameric form of PSI in the thermophilic cyanobacterium Chroococcidiopsis sp TS-821 (TS-821). In TS-821, PSI forms tetrameric and dimeric species. We investigated these species by Blue Native PAGE, Suc density gradient centrifugation, 77K fluorescence, circular dichroism, and single-particle analysis. Transmission electron microscopy analysis of native membranes confirms the presence of the tetrameric PSI structure prior to detergent solubilization. To investigate why TS-821 forms tetramers instead of trimers, we cloned and analyzed its psaL gene. Interestingly, this gene product contains a short insert between the second and third predicted transmembrane helices. Phylogenetic analysis based on PsaL protein sequences shows that TS-821 is closely related to heterocyst-forming cyanobacteria, some of which also have a tetrameric form of PSI. These results are discussed in light of chloroplast evolution, and we propose that PSI evolved stepwise from a trimeric form to tetrameric oligomer en route to becoming monomeric in plants/algae.

  12. Potassium in diet

    Science.gov (United States)

    ... diet; Hypokalemia - potassium in the diet; Chronic kidney disease - potassium in diet; Kidney failure - potassium in diet ... potassium. Vegetables including broccoli, peas, lima beans, tomatoes, potatoes (especially their skins), sweet potatoes, and winter squash ...

  13. A mannose-specific tetrameric lectin with mitogenic and antibacterial activities from the ovary of a teleost, the cobia (Rachycentron canadum).

    Science.gov (United States)

    Ngai, Patrick H K; Ng, T B

    2007-02-01

    A tetrameric lectin, with hemagglutinating activity toward rabbit erythrocytes and with specificity toward D-mannosamine and D(+)-mannose, was isolated from the ovaries of a teleost, the cobia Rachycentron canadum. The isolation protocol comprised ion exchange chromatography on CM-cellulose and Q-Sepharose, ion exchange chromatography by fast protein liquid chromatography (FPLC) on Mono Q, and finally gel filtration by FPLC on Superose 12. The lectin was adsorbed on all ion exchangers used. It exhibited a molecular mass of 180 kDa in gel filtration on Superose 12 and a single 45-kDa band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that it is a tetrameric protein. The hemagglutinating activity of the lectin was stable up to 40 degrees C and between pH 4 and pH 10. All hemagglutinating activity disappeared at 60 degrees C and at pH 1 and pH 13. The hemagglutinating activity was doubled in the presence of 0.1 microM FeCl3. The lectin exerted antibacterial activity against Escherichia coli with 50% inhibition at 250 microg. There was no antifungal activity toward Coprinus comatus, Fusarium oxysporum, Mycosphaerella arachidicola, and Rhizoctonia solani at a dose of 300 microg. The lectin exhibited maximal mitogenic response from mouse splenocytes at a concentration of 14 microM.

  14. Maturation and processing of the amyloid precursor protein is regulated by the potassium/sodium hyperpolarization-activated cyclic nucleotide-gated ion channel 2 (HCN2).

    Science.gov (United States)

    Frykman, Susanne; Inoue, Mitsuhiro; Ikeda, Atsushi; Teranishi, Yasuhiro; Kihara, Takahiro; Lundgren, Jolanta L; Yamamoto, Natsuko G; Bogdanovic, Nenad; Winblad, Bengt; Schedin-Weiss, Sophia; Tjernberg, Lars O

    2017-01-29

    The toxic amyloid β-peptide (Aβ) is a key player in Alzheimer Disease (AD) pathogenesis and selective inhibition of the production of this peptide is sought for. Aβ is produced by the sequential cleavage of the Aβ precursor protein (APP) by β-secretase (to yield APP-C-terminal fragment β (APP-CTFβ) and soluble APPβ (sAPPβ)) and γ-secretase (to yield Aβ). We reasoned that proteins that associate with γ-secretase are likely to regulate Aβ production and to be targets of pharmaceutical interventions and therefore performed a pull-down assay to screen for such proteins in rat brain. Interestingly, one of the purified proteins was potassium/sodium hyperpolarization-activated cyclic nucleotide-gated ion channel 2 (HCN2), which has been shown to be involved in epilepsy. We found that silencing of HCN2 resulted in decreased secreted Aβ levels. To further investigate the mechanism behind this reduction, we also determined the levels of full-length APP, sAPP and APP-CTF species after silencing of HCN2. A marked reduction in sAPP and APP-CTF, as well as glycosylated APP levels was detected. Decreased Aβ, sAPP and APP-CTF levels were also detected after treatment with the HCN2 inhibitor ZD7288. These results indicate that the effect on Aβ levels after HCN2 silencing or inhibition is due to altered APP maturation or processing by β-secretase rather than a direct effect on γ-secretase. However, HCN2 and γ-secretase were found to be in close proximity, as evident by proximity ligation assay and immunoprecipitation. In summary, our results indicate that silencing or inhibition of HCN2 affects APP processing and thereby could serve as a potential treatment strategy. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Pore hydration states of KcsA potassium channels in membranes.

    Science.gov (United States)

    Blasic, Joseph R; Worcester, David L; Gawrisch, Klaus; Gurnev, Philip; Mihailescu, Mihaela

    2015-10-30

    Water-filled hydrophobic cavities in channel proteins serve as gateways for transfer of ions across membranes, but their properties are largely unknown. We determined water distributions along the conduction pores in two tetrameric channels embedded in lipid bilayers using neutron diffraction: potassium channel KcsA and the transmembrane domain of M2 protein of influenza A virus. For the KcsA channel in the closed state, the distribution of water is peaked in the middle of the membrane, showing water in the central cavity adjacent to the selectivity filter. This water is displaced by the channel blocker tetrabutyl-ammonium. The amount of water associated with the channel was quantified, using neutron diffraction and solid state NMR. In contrast, the M2 proton channel shows a V-shaped water profile across the membrane, with a narrow constriction at the center, like the hourglass shape of its internal surface. These two types of water distribution are therefore very different in their connectivity to the bulk water. The water and protein profiles determined here provide important evidence concerning conformation and hydration of channels in membranes and the potential role of pore hydration in channel gating. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. The inhibitory effects of potassium chloride versus potassium silicate application on (137)Cs uptake by rice.

    Science.gov (United States)

    Fujimura, Shigeto; Yoshioka, Kunio; Ota, Takeshi; Ishikawa, Tetsuya; Sato, Makoto; Satou, Mutsuto

    2016-03-01

    After the accident at the Fukushima Dai-ichi Nuclear Power Plant owned by the Tokyo Electric Power Company on 11 March 2011, potassium fertilizer was applied to agricultural fields in the southern Tohoku and northern Kanto regions of Japan to reduce the uptake of radiocesium by crops. In this study, we examined the effects of two types of potassium fertilizers, potassium chloride (a readily available potassium fertilizer) and potassium silicate (a slow-release potassium fertilizer), as well as a split application of potassium, on the accumulation of (137)Cs by rice plants in two pot experiments. The (137)Cs concentrations in the brown rice and in the above-ground plants were significantly lower after potassium chloride application than after potassium silicate application. The potassium ion (K(+)) concentrations in soil solutions sampled 9 and 21 d after transplanting were significantly higher for the potassium chloride application than for the potassium silicate application. The K(+) concentrations in soil solutions observed in the application of potassium silicate were similar to those in the treatment when no potassium was applied. This finding indicates that the application of potassium silicate did not sufficiently increase the available K(+) for rice plants in the soil, which led to a greater uptake of (137)Cs after the potassium silicate application than after the application of potassium chloride. The (137)Cs concentration in brown rice was higher in the split application of potassium fertilizer with the second application at the full heading stage than that without split application and the split application with the second application before heading. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Crystal structure and functional interpretation of the erythrocyte spectrin tetramerization domain complex

    Energy Technology Data Exchange (ETDEWEB)

    Ipsaro, Jonathan J.; Harper, Sandra L.; Messick, Troy E.; Marmorstein, Ronen; Mondragón, Alfonso; Speicher, David W. (Wistar); (NWU)

    2010-09-07

    As the principal component of the membrane skeleton, spectrin confers integrity and flexibility to red cell membranes. Although this network involves many interactions, the most common hemolytic anemia mutations that disrupt erythrocyte morphology affect the spectrin tetramerization domains. Although much is known clinically about the resulting conditions (hereditary elliptocytosis and pyropoikilocytosis), the detailed structural basis for spectrin tetramerization and its disruption by hereditary anemia mutations remains elusive. Thus, to provide further insights into spectrin assembly and tetramer site mutations, a crystal structure of the spectrin tetramerization domain complex has been determined. Architecturally, this complex shows striking resemblance to multirepeat spectrin fragments, with the interacting tetramer site region forming a central, composite repeat. This structure identifies conformational changes in {alpha}-spectrin that occur upon binding to {beta}-spectrin, and it reports the first structure of the {beta}-spectrin tetramerization domain. Analysis of the interaction surfaces indicates an extensive interface dominated by hydrophobic contacts and supplemented by electrostatic complementarity. Analysis of evolutionarily conserved residues suggests additional surfaces that may form important interactions. Finally, mapping of hereditary anemia-related mutations onto the structure demonstrate that most, but not all, local hereditary anemia mutations map to the interacting domains. The potential molecular effects of these mutations are described.

  18. Crystal Structure and Functional Interpretation of the Erythrocyte spectrin Tetramerization Domain Complex

    Energy Technology Data Exchange (ETDEWEB)

    J Ipsaro; S Harper; T Messick; R Marmorstein; A Mondragon; D Speicher

    2011-12-31

    As the principal component of the membrane skeleton, spectrin confers integrity and flexibility to red cell membranes. Although this network involves many interactions, the most common hemolytic anemia mutations that disrupt erythrocyte morphology affect the spectrin tetramerization domains. Although much is known clinically about the resulting conditions (hereditary elliptocytosis and pyropoikilocytosis), the detailed structural basis for spectrin tetramerization and its disruption by hereditary anemia mutations remains elusive. Thus, to provide further insights into spectrin assembly and tetramer site mutations, a crystal structure of the spectrin tetramerization domain complex has been determined. Architecturally, this complex shows striking resemblance to multirepeat spectrin fragments, with the interacting tetramer site region forming a central, composite repeat. This structure identifies conformational changes in {alpha}-spectrin that occur upon binding to {beta}-spectrin, and it reports the first structure of the {beta}-spectrin tetramerization domain. Analysis of the interaction surfaces indicates an extensive interface dominated by hydrophobic contacts and supplemented by electrostatic complementarity. Analysis of evolutionarily conserved residues suggests additional surfaces that may form important interactions. Finally, mapping of hereditary anemia-related mutations onto the structure demonstrate that most, but not all, local hereditary anemia mutations map to the interacting domains. The potential molecular effects of these mutations are described.

  19. Structural analysis of β-glucosidase mutants derived from a hyperthermophilic tetrameric structure

    Energy Technology Data Exchange (ETDEWEB)

    Nakabayashi, Makoto; Kataoka, Misumi; Mishima, Yumiko; Maeno, Yuka; Ishikawa, Kazuhiko, E-mail: kazu-ishikawa@aist.go.jp [National Institute of Advanced Industrial Science, 3-11-32, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 (Japan)

    2014-03-01

    Substitutive mutations that convert a tetrameric β-glucosidase into a dimeric state lead to improvement of its crystal quality. β-Glucosidase from Pyrococcus furiosus (BGLPf) is a hyperthermophilic tetrameric enzyme which can degrade cellooligosaccharides to glucose under hyperthermophilic conditions and thus holds promise for the saccharification of lignocellulosic biomass at high temperature. Prior to the production of large amounts of this enzyme, detailed information regarding the oligomeric structure of the enzyme is required. Several crystals of BGLPf have been prepared over the past ten years, but its crystal structure had not been solved until recently. In 2011, the first crystal structure of BGLPf was solved and a model was constructed at somewhat low resolution (2.35 Å). In order to obtain more detailed structural data on BGLPf, the relationship between its tetrameric structure and the quality of the crystal was re-examined. A dimeric form of BGLPf was constructed and its crystal structure was solved at a resolution of 1.70 Å using protein-engineering methods. Furthermore, using the high-resolution crystal structural data for the dimeric form, a monomeric form of BGLPf was constructed which retained the intrinsic activity of the tetrameric form. The thermostability of BGLPf is affected by its oligomeric structure. Here, the biophysical and biochemical properties of engineered dimeric and monomeric BGLPfs are reported, which are promising prototype models to apply to the saccharification reaction. Furthermore, details regarding the oligomeric structures of BGLPf and the reasons why the mutations yielded improved crystal structures are discussed.

  20. Crystal Structure of Tetrameric Arabidopsis MYC2 Reveals the Mechanism of Enhanced Interaction with DNA

    Directory of Open Access Journals (Sweden)

    Teng-fei Lian

    2017-05-01

    Full Text Available Jasmonates (JAs are essential plant hormones that play important roles in the regulation of plant growth and the response to environmental stress. In the JA signaling pathway, the core transcription factors are a class of basic helix-loop-helix (bHLH proteins, including MYC2, MYC3, and MYC4, that have different regulatory capacities. Here, we report the 2.7 Å crystal structure of the MYC2 bHLH domain complexed with G-box DNA, showing a cis-tetrameric structure. Biochemical assays confirmed that full-length MYC2 forms a stable homo-tetramer both in solution and in DNA-bound states, whereas MYC3 forms only a homodimer. Isothermal titration calorimetry (ITC assays demonstrated that tetramerization enhanced DNA binding affinity, and fluorescence resonance energy transfer (FRET assay indicated DNA looping potential of tetrameric MYC2. Luciferase assay further confirmed the importance of tetramerization in transcriptional regulation. Our studies provide a mechanistic explanation for the regulatory differences of MYC transcription factors.

  1. Potassium Intake, Bioavailability, Hypertension, and Glucose Control

    Directory of Open Access Journals (Sweden)

    Michael S. Stone

    2016-07-01

    Full Text Available Potassium is an essential nutrient. It is the most abundant cation in intracellular fluid where it plays a key role in maintaining cell function. The gradient of potassium across the cell membrane determines cellular membrane potential, which is maintained in large part by the ubiquitous ion channel the sodium-potassium (Na+-K+ ATPase pump. Approximately 90% of potassium consumed (60–100 mEq is lost in the urine, with the other 10% excreted in the stool, and a very small amount lost in sweat. Little is known about the bioavailability of potassium, especially from dietary sources. Less is understood on how bioavailability may affect health outcomes. Hypertension (HTN is the leading cause of cardiovascular disease (CVD and a major financial burden ($50.6 billion to the US public health system, and has a significant impact on all-cause morbidity and mortality worldwide. The relationship between increased potassium supplementation and a decrease in HTN is relatively well understood, but the effect of increased potassium intake from dietary sources on blood pressure overall is less clear. In addition, treatment options for hypertensive individuals (e.g., thiazide diuretics may further compound chronic disease risk via impairments in potassium utilization and glucose control. Understanding potassium bioavailability from various sources may help to reveal how specific compounds and tissues influence potassium movement, and further the understanding of its role in health.

  2. Potassium Blood Test

    Science.gov (United States)

    ... page: https://medlineplus.gov/labtests/potassiumbloodtest.html Potassium Blood Test To use the sharing features on this page, please enable JavaScript. What is a Potassium Blood Test? A potassium blood test measures the amount of ...

  3. A novel tetrameric gp350 1-470 as a potential Epstein-Barr virus vaccine.

    Science.gov (United States)

    Cui, Xinle; Cao, Zhouhong; Sen, Goutam; Chattopadhyay, Gouri; Fuller, Deborah H; Fuller, James T; Snapper, Dustin M; Snow, Andrew L; Mond, James J; Snapper, Clifford M

    2013-06-26

    Infectious mononucleosis and B-cell transformation in response to infection with Epstein-Barr virus (EBV) is dependent upon binding of the EBV envelope glycoprotein gp350 to CD21 on B-cells. Gp350-specific antibody comprises most of the EBV neutralizing activity in the serum of infected patients, making this protein a promising target antigen for a prophylactic EBV vaccine. We describe a novel, tetrameric gp350-based vaccine that exhibits markedly enhanced immunogenicity relative to its monomeric counterpart. Plasmid DNA was constructed for synthesis, within transfected CHO cells, of a tetrameric, truncated (a.a. 1-470) gp350 protein (gp350(1-470)). Tetrameric gp350(1-470) induced ≈ 20-fold higher serum titers of gp350(1-470)-specific IgG and >19-fold enhancements in neutralizing titers at the highest dose, and was >25-fold more immunogenic on a per-weight basis than monomeric gp350(1-470). Further, epidermal immunization with plasmid DNA encoding gp350(1-470) tetramer induced 8-fold higher serum titers of gp350(1-470)-specific IgG relative to monomer. Tetrameric gp350(1-470) binding to human CD21 was >24-fold more efficient on a per-weight basis than monomer, but neither tetramer nor monomer mediated polyclonal human B-cell activation. Finally, the introduction of strong, universal tetanus toxoid (TT)-specific CD4+ T-cell epitopes into the tetrameric gp350(1-470) had no effect on the gp350(1-470)-specific IgG response in naïve mice, and resulted in suppressed gp350(1-470)-specific IgG responses in TT-primed mice. Collectively, these data suggest that tetrameric gp350(1-470) is a potentially promising candidate for testing as a prophylactic EBV vaccine, and that protein multimerization, using the approach described herein, is likely to be clinically relevant for enhancing the immunogenicity of other proteins of vaccine interest. Published by Elsevier Ltd.

  4. Adaptation of Bacillus subtilis to Life at Extreme Potassium Limitation

    Directory of Open Access Journals (Sweden)

    Jan Gundlach

    2017-07-01

    Full Text Available Potassium is the most abundant metal ion in every living cell. This ion is essential due to its requirement for the activity of the ribosome and many enzymes but also because of its role in buffering the negative charge of nucleic acids. As the external concentrations of potassium are usually low, efficient uptake and intracellular enrichment of the ion is necessary. The Gram-positive bacterium Bacillus subtilis possesses three transporters for potassium, KtrAB, KtrCD, and the recently discovered KimA. In the absence of the high-affinity transporters KtrAB and KimA, the bacteria were unable to grow at low potassium concentrations. However, we observed the appearance of suppressor mutants that were able to overcome the potassium limitation. All these suppressor mutations affected amino acid metabolism, particularly arginine biosynthesis. In the mutants, the intracellular levels of ornithine, citrulline, and arginine were strongly increased, suggesting that these amino acids can partially substitute for potassium. This was confirmed by the observation that the supplementation with positively charged amino acids allows growth of B. subtilis even at the extreme potassium limitation that the bacteria experience if no potassium is added to the medium. In addition, a second class of suppressor mutations allowed growth at extreme potassium limitation. These mutations result in increased expression of KtrAB, the potassium transporter with the highest affinity and therefore allow the acquisition and accumulation of the smallest amounts of potassium ions from the environment.

  5. Crystal structure of the sodium-potassium pump

    DEFF Research Database (Denmark)

    Morth, J Preben; Pedersen, Bjørn Panyella; Toustrup-Jensen, Mads S

    2007-01-01

    The Na+,K+-ATPase generates electrochemical gradients for sodium and potassium that are vital to animal cells, exchanging three sodium ions for two potassium ions across the plasma membrane during each cycle of ATP hydrolysis. Here we present the X-ray crystal structure at 3.5 A resolution of the...

  6. A eukaryotic specific transmembrane segment is required for tetramerization in AMPA receptors.

    Science.gov (United States)

    Salussolia, Catherine L; Gan, Quan; Kazi, Rashek; Singh, Puja; Allopenna, Janet; Furukawa, Hiro; Wollmuth, Lonnie P

    2013-06-05

    Most fast excitatory synaptic transmission in the nervous system is mediated by glutamate acting through ionotropic glutamate receptors (iGluRs). iGluRs (AMPA, kainate, and NMDA receptor subtypes) are tetrameric assemblies, formed as a dimer of dimers. Still, the mechanism underlying tetramerization--the necessary step for the formation of functional receptors that can be inserted into the plasma membrane--is unknown. All eukaryotic compared to prokaryotic iGluR subunits have an additional transmembrane segment, the M4 segment, which positions the physiologically critical C-terminal domain on the cytoplasmic side of the membrane. AMPA receptor (AMPAR) subunits lacking M4 do not express on the plasma membrane. Here, we show that these constructs are retained in the endoplasmic reticulum, the major cellular compartment mediating protein oligomerization. Using approaches to assay the native oligomeric state of AMPAR subunits, we find that subunits lacking M4 or containing single amino acid substitutions along an "interacting" face of the M4 helix that block surface expression no longer tetramerize in either homomeric or heteromeric assemblies. In contrast, subunit dimerization appears to be largely intact. These experiments define the M4 segment as a unique functional unit in AMPARs that is required for the critical dimer-to-tetramer transition.

  7. Structural, kinetic, and mutational studies of the zinc ion environment in tetrameric cytidine deaminase

    DEFF Research Database (Denmark)

    Johansson, Eva; Neuhard, Jan; Willemoës, Martin

    2004-01-01

    of the zinc-liganding cysteines has been substituted by histidine to mimic D-CDA, alone (C53H) and in combination with R56Q (C53H/R56Q). R56A, R56Q, and C53H/R56Q contain the same amount of zinc as the wild-type enzyme. The zinc-binding capacity of R56D is reduced. Only R56A, R56Q, and C53H/R56Q yielded...... measurable CDA activity, R56A and R56Q with similar K(m) but decreased V(max) values compared to wild-type enzyme. Because of dissociation into its inactive subunits, it was impossible to determine the kinetic parameters for C53H/R56Q. R56A and C53H/R56Q display increased apparent pK(a) values compared...... to the wild-type enzyme and R56Q. On the basis of the structures of R56A, R56Q, and C53H/R56Q an explanation is provided of kinetic results and the apparent instability of C53H/R56Q....

  8. Penicillin V Potassium

    Science.gov (United States)

    Penicillin V potassium is an antibiotic used to treat certain infections caused by bacteria such as pneumonia, ... Penicillin V potassium comes as a tablet and liquid to take by mouth. It is usually taken ...

  9. Potassium 4-azidobenzenesulfonate

    Directory of Open Access Journals (Sweden)

    Frank Biesemeier

    2014-08-01

    Full Text Available In, K+·SO3–p-C6H4–N3−, the conformation angle of the azido group with respect to the benzene ring is 19.1 (3°, so that the anion is chiral within the crystal structure. In addition, the crystal structure is also chiral (Sohncke space group. The potassium ion is coordinated by three closer O atoms from three different sulfonyl groups [K...O 2.6486 (17 to 2.7787 (17 Å], three more distant O atoms [K...O 2.959 (2 to 3.206 (2 Å] and three N atoms at 3.073 (2 to 3.268 (2 Å. The anions are packed into layers perpendicular to b, only O and N atoms being at the surface of the layers. The K+ ions are located between the layers.

  10. Efficient and specific internal cleavage of a retroviral palindromic DNA sequence by tetrameric HIV-1 integrase.

    Directory of Open Access Journals (Sweden)

    Olivier Delelis

    Full Text Available BACKGROUND: HIV-1 integrase (IN catalyses the retroviral integration process, removing two nucleotides from each long terminal repeat and inserting the processed viral DNA into the target DNA. It is widely assumed that the strand transfer step has no sequence specificity. However, recently, it has been reported by several groups that integration sites display a preference for palindromic sequences, suggesting that a symmetry in the target DNA may stabilise the tetrameric organisation of IN in the synaptic complex. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the ability of several palindrome-containing sequences to organise tetrameric IN and investigated the ability of IN to catalyse DNA cleavage at internal positions. Only one palindromic sequence was successfully cleaved by IN. Interestingly, this symmetrical sequence corresponded to the 2-LTR junction of retroviral DNA circles-a palindrome similar but not identical to the consensus sequence found at integration sites. This reaction depended strictly on the cognate retroviral sequence of IN and required a full-length wild-type IN. Furthermore, the oligomeric state of IN responsible for this cleavage differed from that involved in the 3'-processing reaction. Palindromic cleavage strictly required the tetrameric form, whereas 3'-processing was efficiently catalysed by a dimer. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that the restriction-like cleavage of palindromic sequences may be a general physiological activity of retroviral INs and that IN tetramerisation is strongly favoured by DNA symmetry, either at the target site for the concerted integration or when the DNA contains the 2-LTR junction in the case of the palindromic internal cleavage.

  11. KV7 potassium channels

    DEFF Research Database (Denmark)

    Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A

    2014-01-01

    Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

  12. Characterization and Evolution of Tetrameric Photosystem I from the Thermophilic Cyanobacterium Chroococcidiopsis sp TS-821[C][W][OPEN

    Science.gov (United States)

    Li, Meng; Semchonok, Dmitry A.; Boekema, Egbert J.; Bruce, Barry D.

    2014-01-01

    Photosystem I (PSI) is a reaction center associated with oxygenic photosynthesis. Unlike the monomeric reaction centers in green and purple bacteria, PSI forms trimeric complexes in most cyanobacteria with a 3-fold rotational symmetry that is primarily stabilized via adjacent PsaL subunits; however, in plants/algae, PSI is monomeric. In this study, we discovered a tetrameric form of PSI in the thermophilic cyanobacterium Chroococcidiopsis sp TS-821 (TS-821). In TS-821, PSI forms tetrameric and dimeric species. We investigated these species by Blue Native PAGE, Suc density gradient centrifugation, 77K fluorescence, circular dichroism, and single-particle analysis. Transmission electron microscopy analysis of native membranes confirms the presence of the tetrameric PSI structure prior to detergent solubilization. To investigate why TS-821 forms tetramers instead of trimers, we cloned and analyzed its psaL gene. Interestingly, this gene product contains a short insert between the second and third predicted transmembrane helices. Phylogenetic analysis based on PsaL protein sequences shows that TS-821 is closely related to heterocyst-forming cyanobacteria, some of which also have a tetrameric form of PSI. These results are discussed in light of chloroplast evolution, and we propose that PSI evolved stepwise from a trimeric form to tetrameric oligomer en route to becoming monomeric in plants/algae. PMID:24681621

  13. Single crystal EPR studies of paramagnetic ions doped zinc potassium phosphate hexahydrate. Part III: Mn(II)—a case of rhombic distortion

    Science.gov (United States)

    Anandalakshmi, H.; Sougandi, I.; Velavan, K.; Venkatesan, R.; Rao, P. S.

    2004-09-01

    Single crystal electron paramagnetic resonance (EPR) studies of Mn(II) doped zinc potassium phosphate hexahydrate have been carried out at room temperature. Single crystal rotations along the three orthogonal axes indicate orthorhombic symmetry with spin-Hamiltonian parameters as: gxx=1.9997; gyy=1.9538; gzz=1.9524, Dxx=15.49 mT; Dyy=0.22 mT; Dzz=-15.71 mT, Axx=11.70 mT; Ayy=10.53 mT; Azz=10.42 mT and a=0.8×10 -4 cm -1. A large E term indicates considerable distortion from axial symmetry. The impurity is found to enter the lattice substitutionally. The distortion axis for the impurity has been identified along one of the ZnO bond directions in the crystal.

  14. Single crystal EPR studies of paramagnetic ions doped zinc potassium phosphate hexahydrate; Part III: Mn(II)-a case of rhombic distortion.

    Science.gov (United States)

    Anandalakshmi, H; Sougandi, I; Velavan, K; Venkatesan, R; Rao, P S

    2004-09-01

    Single crystal electron paramagnetic resonance (EPR) studies of Mn(II) doped zinc potassium phosphate hexahydrate have been carried out at room temperature. Single crystal rotations along the three orthogonal axes indicate orthorhombic symmetry with spin-Hamiltonian parameters as: g(xx) = 1.9997; g(yy) = 1.9538; g(zz) = 1.9524, D(xx) = 15.49 mT; D(yy) = 0.22 mT; D(zz) = -15.71 mT, A(xx) = 11.70 mT; A(yy) = 10.53 mT; A(zz) = 10.42 mT and a = 0.8 x 10(-4) cm(-1). A large E term indicates considerable distortion from axial symmetry. The impurity is found to enter the lattice substitutionally. The distortion axis for the impurity has been identified along one of the Zn-O bond directions in the crystal.

  15. VKCDB: Voltage-gated potassium channel database

    Directory of Open Access Journals (Sweden)

    Gallin Warren J

    2004-01-01

    Full Text Available Abstract Background The family of voltage-gated potassium channels comprises a functionally diverse group of membrane proteins. They help maintain and regulate the potassium ion-based component of the membrane potential and are thus central to many critical physiological processes. VKCDB (Voltage-gated potassium [K] Channel DataBase is a database of structural and functional data on these channels. It is designed as a resource for research on the molecular basis of voltage-gated potassium channel function. Description Voltage-gated potassium channel sequences were identified by using BLASTP to search GENBANK and SWISSPROT. Annotations for all voltage-gated potassium channels were selectively parsed and integrated into VKCDB. Electrophysiological and pharmacological data for the channels were collected from published journal articles. Transmembrane domain predictions by TMHMM and PHD are included for each VKCDB entry. Multiple sequence alignments of conserved domains of channels of the four Kv families and the KCNQ family are also included. Currently VKCDB contains 346 channel entries. It can be browsed and searched using a set of functionally relevant categories. Protein sequences can also be searched using a local BLAST engine. Conclusions VKCDB is a resource for comparative studies of voltage-gated potassium channels. The methods used to construct VKCDB are general; they can be used to create specialized databases for other protein families. VKCDB is accessible at http://vkcdb.biology.ualberta.ca.

  16. Alternatively Spliced Isoforms of KV10.1 Potassium Channels Modulate Channel Properties and Can Activate Cyclin-dependent Kinase in Xenopus Oocytes*

    Science.gov (United States)

    Ramos Gomes, Fernanda; Romaniello, Vincenzo; Sánchez, Araceli; Weber, Claudia; Narayanan, Pratibha; Psol, Maryna; Pardo, Luis A.

    2015-01-01

    KV10.1 is a voltage-gated potassium channel expressed selectively in the mammalian brain but also aberrantly in cancer cells. In this study we identified short splice variants of KV10.1 resulting from exon-skipping events (E65 and E70) in human brain and cancer cell lines. The presence of the variants was confirmed by Northern blot and RNase protection assays. Both variants completely lacked the transmembrane domains of the channel and produced cytoplasmic proteins without channel function. In a reconstituted system, both variants co-precipitated with the full-length channel and induced a robust down-regulation of KV10.1 current when co-expressed with the full-length form, but their effect was mechanistically different. E65 required a tetramerization domain and induced a reduction in the overall expression of full-length KV10.1, whereas E70 mainly affected its glycosylation pattern. E65 triggered the activation of cyclin-dependent kinases in Xenopus laevis oocytes, suggesting a role in cell cycle control. Our observations highlight the relevance of noncanonical functions for the oncogenicity of KV10.1, which need to be considered when ion channels are targeted for cancer therapy. PMID:26518875

  17. Alternatively Spliced Isoforms of KV10.1 Potassium Channels Modulate Channel Properties and Can Activate Cyclin-dependent Kinase in Xenopus Oocytes.

    Science.gov (United States)

    Ramos Gomes, Fernanda; Romaniello, Vincenzo; Sánchez, Araceli; Weber, Claudia; Narayanan, Pratibha; Psol, Maryna; Pardo, Luis A

    2015-12-18

    KV10.1 is a voltage-gated potassium channel expressed selectively in the mammalian brain but also aberrantly in cancer cells. In this study we identified short splice variants of KV10.1 resulting from exon-skipping events (E65 and E70) in human brain and cancer cell lines. The presence of the variants was confirmed by Northern blot and RNase protection assays. Both variants completely lacked the transmembrane domains of the channel and produced cytoplasmic proteins without channel function. In a reconstituted system, both variants co-precipitated with the full-length channel and induced a robust down-regulation of KV10.1 current when co-expressed with the full-length form, but their effect was mechanistically different. E65 required a tetramerization domain and induced a reduction in the overall expression of full-length KV10.1, whereas E70 mainly affected its glycosylation pattern. E65 triggered the activation of cyclin-dependent kinases in Xenopus laevis oocytes, suggesting a role in cell cycle control. Our observations highlight the relevance of noncanonical functions for the oncogenicity of KV10.1, which need to be considered when ion channels are targeted for cancer therapy. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Simultaneous determination of free calcium, magnesium, sodium and potassium ion concentrations in simulated milk ultrafiltrate and reconstituted skim milk using the Donnan Membrane Technique

    NARCIS (Netherlands)

    Gao, R.; Temminghoff, E.J.M.; Leeuwen, van H.P.; Valenberg, van H.J.F.; Eisner, M.D.; Boekel, van M.A.J.S.

    2009-01-01

    This study focused on determination of free Ca2+, Mg2+, Na+ and K+ concentrations in a series of CaCl2 solutions, simulated milk ultrafiltrate and reconstituted skim milk using a recently developed Donnan Membrane Technique (DMT). A calcium ion selective electrode was used to compare the DMT

  19. Adaptation of Bacillus subtilis to Life at Extreme Potassium Limitation.

    Science.gov (United States)

    Gundlach, Jan; Herzberg, Christina; Hertel, Dietrich; Thürmer, Andrea; Daniel, Rolf; Link, Hannes; Stülke, Jörg

    2017-07-05

    Potassium is the most abundant metal ion in every living cell. This ion is essential due to its requirement for the activity of the ribosome and many enzymes but also because of its role in buffering the negative charge of nucleic acids. As the external concentrations of potassium are usually low, efficient uptake and intracellular enrichment of the ion is necessary. The Gram-positive bacterium Bacillus subtilis possesses three transporters for potassium, KtrAB, KtrCD, and the recently discovered KimA. In the absence of the high-affinity transporters KtrAB and KimA, the bacteria were unable to grow at low potassium concentrations. However, we observed the appearance of suppressor mutants that were able to overcome the potassium limitation. All these suppressor mutations affected amino acid metabolism, particularly arginine biosynthesis. In the mutants, the intracellular levels of ornithine, citrulline, and arginine were strongly increased, suggesting that these amino acids can partially substitute for potassium. This was confirmed by the observation that the supplementation with positively charged amino acids allows growth of B. subtilis even at the extreme potassium limitation that the bacteria experience if no potassium is added to the medium. In addition, a second class of suppressor mutations allowed growth at extreme potassium limitation. These mutations result in increased expression of KtrAB, the potassium transporter with the highest affinity and therefore allow the acquisition and accumulation of the smallest amounts of potassium ions from the environment.IMPORTANCE Potassium is essential for every living cell as it is required for the activity for many enzymes and for maintaining the intracellular pH by buffering the negative charge of the nucleic acids. We have studied the adaptation of the soil bacterium Bacillus subtilis to life at low potassium concentrations. If the major high-affinity transporters are missing, the bacteria are unable to grow unless

  20. Lanthanide-Potassium Biphenyl-3,3'-disulfonyl-4,4'-dicarboxylate Frameworks: Gas Sorption, Proton Conductivity, and Luminescent Sensing of Metal Ions.

    Science.gov (United States)

    Zhou, Li-Juan; Deng, Wei-Hua; Wang, Yu-Ling; Xu, Gang; Yin, Shun-Gao; Liu, Qing-Yan

    2016-06-20

    A novel sulfonate-carboxylate ligand of biphenyl-3,3'-disulfonyl-4,4'-dicarboxylic acid (H4-BPDSDC) and its lanthanide-organic frameworks {[LnK(BPDSDC)(DMF)(H2O)]·x(solvent)}n (JXNU-2, where JXNU denotes Jiangxi Normal University, DMF indicates dimethylformamide, and Ln = Sm(3+), Eu(3+), and Pr(3+)) were synthesized and structurally characterized. The three isomorphous lanthanide compounds feature three-dimensional frameworks constructed from one-dimensional (1D) rod-shaped heterometallic Ln-K secondary building units and are an illustration of a Kagome-like lattice with large 1D hexagonal channels and small 1D trigonal channels. The porous material of the representive JXNU-2(Sm) has an affinity to quadrupolar molecules such as CO2 and C2H2. In addition, the JXNU-2(Sm) compound exhibits humidity- and temperature-dependent proton conductivity with a large value of 1.11 × 10(-3) S cm(-1) at 80 °C and 98% relative humidity. The hydrophilic sulfonate group on the surface of channels facilitates enrichment of the solvate water molecules in the channels, which enhances the proton conductivity of this material. Moreover, the JXNU-2(Eu) material with the characteristic bright red color shows the potential for recognition of K(+) and Fe(3+) ions. The enhancing Eu(3+) luminescence with the K(+) ion and quenching Eu(3+) luminescence with the Fe(3+) ion can be associated with the functional groups of the organic ligand.

  1. Ion-molecular interactions in solutions of potassium and cadmium thiocyanates in N-methylpyrrolidone at 298.15 k, according to calorimetry and densitometry data

    Science.gov (United States)

    Rassokhina, L. Yu.; Novikov, A. N.

    2013-11-01

    The heat capacity and density of KNCS-N-methylpyrrolidone (MP), Cd(NCS)2-MP, and KNCS-Cd(NCS)2-MP solutions at 298.15 K are studied by means of calorimetry and densitometry. Standard partial molar heat capacities and volumes ( and ) of the studied electrolytes in MP are calculated. Standard values of heat capacity and volume of NCS- ions in MP at 298.15 K are determined. Values of the heat capacity and volume changes upon the formation of the three-component system KNCS-Cd(NCS)2-MP from binary solutions are obtained and discussed.

  2. PET imaging of alphavbeta integrin expression in tumours with Ga-labelled mono-, di- and tetrameric RGD peptides

    NARCIS (Netherlands)

    Dijkgraaf, I.; Yim, C.B.; Franssen, G.M.; Schuit, R.C.; Luurtsema, G.; Liu, S.; Oyen, W.J.G.; Boerman, O.C.

    2011-01-01

    PURPOSE: Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3)-binding characteristics of (68)Ga-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared

  3. Study of vibrational spectra and hydrogen bonding network in dimeric and tetrameric model of ampicillin using DFT and AIM approach

    Science.gov (United States)

    Shukla, Anuradha; Khan, Eram; Tandon, Poonam; Sinha, Kirti

    2017-03-01

    Ampicillin is a β-lactam antibiotic that is active against both gram-positive and gram-negative bacteria and is widely used for the treatment of infections. In this work, molecular properties of ampicillin are calculated on the basis of calculations on its dimeric and tetrameric models using DFT/B3LYP/6-311G(d,p). HOMO-LUMO energy gap shows that chemical reactivity of tetrameric model of ampicillin is higher than the dimeric and monomeric model of ampicillin. To get a better understanding of intra and intermolecular bonding and interactions among bonds, NBO analysis is carried out with tetrameric model of ampicillin, and is further finalized with an 'quantum theory of atoms-in-molecules' (QTAIM) analysis. The binding energy of dimeric model of ampicillin is calculated as -26.84 kcal/mol and -29.34 kcal/mol using AIM and DFT calculations respectively. The global electrophilicity index (ω = 2.8118 eV) of tetrameric model of ampicillin shows that this behaves as a strong electrophile in comparison to dimeric and monomeric model of ampicillin. The FT-Raman and FT-IR spectra were recorded in the solid phase, and interpreted in terms of potential energy distribution analysis. A collective theoretical and experimental vibrational analysis approves the presence of hydrogen bonds in the ampicillin molecule.

  4. Polyacrylamide gels with selective recognition of the tetrameric molecular form of human growth hormone

    Directory of Open Access Journals (Sweden)

    R. Kublickas

    2017-08-01

    Full Text Available Networks of polyacrylamide were studied for the possibility of imprinting of the oligomeric form of human growth hormone. The tetrameric molecular form of human growth hormone was molecularly imprinted for the first time. The results show that approximately 50–70% (w/w of the templates (depending on polymerization conditions could be extracted from the molecularly imprinted acrylamide polymers. The resulting ‘gel antibodies’ against this form of human growth hormone in the form of granules of polyacrylamide were compared with granules of non-imprinted polymer. The selectivity of the artificial gel antibodies was studied. Investigation of the binding to imprinted polymer of the template hormone, other molecular forms of the hormone and other proteins shows the selectivity of the developed artificial gel antibodies.

  5. Overexpression, purification and crystallization of the tetrameric form of SorC sorbitol operon regulator

    Energy Technology Data Exchange (ETDEWEB)

    Sanctis, Daniele de; Rêgo, Ana T.; Marçal, David; McVey, Colin E.; Carrondo, Maria A. [Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras (Portugal); Enguita, Francisco J., E-mail: fenguita@fm.ul.pt [Instituto de Medicina Molecular, Avenida Professor Egas Moniz, 1649-028 Lisboa (Portugal); Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras (Portugal)

    2008-01-01

    The sorbitol operon regulator from K. pneumoniae has been overexpressed in E. coli, purified and crystallized. Diffraction data were collected to 3.2 Å. The sorbitol operon regulator (SorC) regulates the metabolism of l-sorbose in Klebsiella pneumonia. SorC was overexpressed in Escherichia coli and purified, and crystals were obtained of a tetrameric form. A single crystal showed X-ray diffraction to 3.20 Å. The crystal belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 91.6, b = 113.3, c = 184.1 Å. Analysis of the molecular-replacement solution indicates the presence of four SorC molecules in the asymmetric unit.

  6. Comparative inhibition of tetrameric carbonyl reductase activity in pig heart cytosol by alkyl 4-pyridyl ketones.

    Science.gov (United States)

    Shimada, Hideaki; Tanigawa, Takahiro; Matayoshi, Kazunori; Katakura, Kazufumi; Babazono, Ken; Takayama, Hiroyuki; Murahashi, Tsuyoshi; Akita, Hiroyuki; Higuchi, Toshiyuki; Eto, Masashi; Imamura, Yorishige

    2014-06-01

    The present study is to elucidate the comparative inhibition of tetrameric carbonyl reductase (TCBR) activity by alkyl 4-pyridyl ketones, and to characterize its substrate-binding domain. The inhibitory effects of alkyl 4-pyridyl ketones on the stereoselective reduction of 4-benzoylpyridine (4-BP) catalyzed by TCBR were examined in the cytosolic fraction of pig heart. Of alkyl 4-pyridyl ketones, 4-hexanoylpyridine, which has a straight-chain alkyl group of five carbon atoms, inhibited most potently TCBR activity and was a competitive inhibitor. Furthermore, cyclohexyl pentyl ketone, which is substituted by cyclohexyl group instead of phenyl group of hexanophenone, had much lower ability to be reduced than hexanophenone. These results suggest that in addition to a hydrophobic cleft corresponding to a straight-chain alkyl group of five carbon atoms, a hydrophobic pocket with affinity for an aromatic group is located in the substrate-binding domain of TCBR.

  7. The first transmembrane region of the beta-chain stabilizes the tetrameric Fc epsilon RI complex.

    Science.gov (United States)

    Singleton, Theresa E; Platzer, Barbara; Dehlink, Eleonora; Fiebiger, Edda

    2009-07-01

    The family of activating immune receptors stabilizes via the 3-helix assembly principle. A charged basic transmembrane residue interacts with two charged acidic transmembrane residues and forms a 3-helix interface to stabilize receptor complexes in the lipid bilayer. One family member, the high affinity receptor for IgE, Fc epsilon RI, is a key regulator of immediate allergic responses. Tetrameric Fc epsilon RI consists of the IgE-binding alpha-chain, the multimembrane-spanning beta-chain and a dimer of the gamma-subunit (Fc epsilon R gamma). Comparative analysis of these seven transmembrane regions indicates that Fc epsilon RI does not meet the charge requirements for the 3-helix assembly mechanism. We performed alanine mutagenesis to show that the only basic amino acid in the transmembrane regions, beta K97, is not involved in Fc epsilon RI stabilization or surface upregulation, a hallmark function of the beta-chain. Even a beta K97E mutant is functional despite four negatively charged acidic amino acids in the transmembrane regions. Using truncation mutants, we demonstrate that the first uncharged transmembrane domain of the beta-chain contains the interface for receptor stabilization. In vitro translation experiments depict the first transmembrane region as the internal signal peptide of the beta-chain. We also show that this beta-chain domain can function as a cleavable signal peptide when used as a leader peptide for a Type I protein. Our results provide evidence that tetrameric Fc epsilon RI does not assemble according to the 3-helix assembly principle. We conclude that receptors formed with multispanning proteins use different mechanisms of shielding transmembrane charged amino acids.

  8. Tetrameric structure of the flagellar cap protein FliD from Serratia marcescens.

    Science.gov (United States)

    Cho, So Yeon; Song, Wan Seok; Hong, Ho Jeong; Lee, Geun-Shik; Kang, Seung Goo; Ko, Hyun-Jeong; Kim, Pyeung-Hyeun; Yoon, Sung-Il

    2017-07-15

    Bacterial motility is provided by the flagellum. FliD is located at the distal end of the flagellum and plays a key role in the insertion of each flagellin protein at the growing tip of the flagellar filament. Because FliD functions as an oligomer, the determination of the oligomeric state of FliD is critical to understanding the molecular mechanism of FliD-mediated flagellar growth. FliD has been shown to adopt a pentameric or a hexameric structure depending on the bacterial species. Here, we report another distinct oligomeric form of FliD based on structural and biochemical studies. The crystal structures of the D2 and D3 domains of Serratia marcescens FliD (smFliD) were determined in two crystal forms and together revealed that smFliD assembles into a tetrameric architecture that resembles a four-pointed star plate. smFliD tetramerization was also confirmed in solution by cross-linking experiments. Although smFliD oligomerizes in a head-to-tail orientation using a common primary binding interface between the D2 and D3' domains (the prime denotes the second subunit in the oligomer) similarly to other FliD orthologs, the smFliD tetramer diverges to present a unique secondary D2-D2' binding interface. Our structure-based comparative analysis of FliD suggests that bacteria have developed diverse species-specific oligomeric forms of FliD that range from tetramers to hexamers for flagellar growth. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Intractable hyperkalemia due to nicorandil induced potassium channel syndrome

    Directory of Open Access Journals (Sweden)

    Vivek Chowdhry

    2015-01-01

    Full Text Available Nicorandil is a commonly used antianginal agent, which has both nitrate-like and ATP-sensitive potassium (K ATP channel activator properties. Activation of potassium channels by nicorandil causes expulsion of potassium ions into the extracellular space leading to membrane hyperpolarization, closure of voltage-gated calcium channels and finally vasodilatation. However, on the other hand, being an activator of K ATP channel, it can expel K + ions out of the cells and can cause hyperkalemia. Here, we report a case of nicorandil induced hyperkalemia unresponsive to medical treatment in a patient with diabetic nephropathy.

  10. Hydrogen storage in a potassium-ion-bound metal-organic framework incorporating crown ether struts as specific cation binding sites.

    Science.gov (United States)

    Lim, Dae-Woon; Chyun, Seung An; Suh, Myunghyun Paik

    2014-07-21

    To develop a metal-organic framework (MOF) for hydrogen storage, SNU-200 incorporating a 18-crown-6 ether moiety as a specific binding site for selected cations has been synthesized. SNU-200 binds K(+), NH4(+), and methyl viologen (MV(2+)) through single-crystal to single-crystal transformations. It exhibits characteristic gas-sorption properties depending on the bound cation. SNU-200 activated with supercritical CO2 shows a higher isosteric heat (Qst) of H2 adsorption (7.70 kJ mol(-1)) than other zinc-based MOFs. Among the cation inclusions, K(+) is the best for enhancing the isosteric heat of the H2 adsorption (9.92 kJ mol(-1)) as a result of the accessible open metal sites on the K(+) ion. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A study of physical and optical absorption spectra of VO{sup 2+} ions in potassium and sodium oxide borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, G., E-mail: srinu123g@gmail.com; Ramesh, B.; Kumar, J. Siva; Shareefuddin, Md.; Chary, M. N.; Sayanna, R. [Department of Physics, Osmania University, Hyderabad (India)

    2016-05-23

    Spectroscopic and physical properties of V{sub 2}O{sub 5} doped mixed alkali borate glasses are investigated. Borate glasses containing fixed concentrations of alkaline earth oxides (MgO and BaO) and alkali oxides (K{sub 2}O and Na{sub 2}O) were changes and are prepared by melt quenching technique. The values of r{sub i}, r{sub p}, R{sub m}, α{sub m} molar volume and Λ{sub th} increase and oxygen packing density, density and dopant ion concentration decrease with increasing of K{sub 2}O content. As a result there shall be an increase in the disorder of the glass network. The optical band gap energies, Urbach energy, boron-boron separation,refractive index, dielectric constant, electronic polarizability and reflection loss values are varies nonlinearly with the K{sub 2}O content which manifests the mixed alkali effect.

  12. Potassium maldistribution revisited

    African Journals Online (AJOL)

    Medication errors contribute significantly to human and financial costs.1-4 One of these errors involves incorrect identification of concentrated potassium chloride ampoules. After coronary artery bypass grafting, potassium concentrations lower and higher than 3.3 and 5.2 mmol per liter respectively have been associated ...

  13. Potassium food supplement

    Science.gov (United States)

    Bourland, C. T.; Huber, C. S.; Rambaut, C.; Heidelbaugh, N. D.

    1973-01-01

    Potassium gluconate is considered best supplementary source for potassium. Gluconate consistently received highest taste rating and was indistinguishable from nonsupplemented samples. No unfavorable side effects were found during use, and none are reported in literature. Gluconate is normal intermediary metabolite that is readily adsorbed and produces no evidence of gastrointestinal ulcerations.

  14. Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining; Caracterizacao do po de titanato de bario dopado com ions sodio e potasio com o refinamento de Rietveld

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, M.C.; Assis, J.T.; Pereira, F.R., E-mail: mcalixto@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico; Araujo, J.C. [Universidade do Estado do Rio de Janeiro (FFP/UERJ), Sao Goncalo, RJ (Brazil). Fac. de Formacao de Professores; Moreira, E.L.; Moraes, V.C.A.; Lopes, A.R. [Centro Brasileiro de Pesquisas Fisicas (CBPF/MCT), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO{sub 3} formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

  15. What is Potassium?

    Science.gov (United States)

    ... Workout Nutrition Timing Your Pre- and Post-Workout Nutrition weights and fruits Building Muscle on a Vegetarian Diet For Kids For Parents For Men For Women For Seniors What Is Potassium? Reviewed by Taylor Wolfram, MS, ...

  16. Tetrameric Self-Assembly of a Cu(II) Complex Containing Schiff-Base Ligand and Its Unusually High Catecholase-like Activity

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Shuranjan; Lee, Hongin [Kyungpook National Univ., Daegu (Korea, Republic of); Lee, Woo Ram; Hong, Chang Seop [Korea Univ., Seoul (Korea, Republic of)

    2013-09-15

    We report a new tetrameric supramolecular Cu(II) complex (Cu{sub 4}L{sub 4} = tetrakis(N,N'-bis(salicylidene)-2,2'-ethylenedianiline) Copper(II)) with a Schiff-base ligand (H{sub 2}L = N,N'-bis (salicylaldimine)-1,2-ethylenediamine) containing two N,O-bidentate chelate groups. Though the copper sites of Cu{sub 4}L{sub 4} are non-coupled, the complex exhibits a unusually high catecholase-like activity (k{sub cat} = 935 h{sup -1}) when the Cu{sub 4}L{sub 4} solution is treated with 3,5-di-tert-butylcatechol (3,5-DTBC) at basic condition in the presence of air. Combined information obtained from UV-VIS and EPR measurements could lead the suggestion of the reaction pathway in which the substrate may bind to Cu(II) ions by anti-anti didentate bridging mode.

  17. Determination of the physiological plasmatic values of sodium, potassium and ion calcium and its pre and post exercise Variations in “paso fino” horses in the bogota savannah

    Directory of Open Access Journals (Sweden)

    Camila Valdés Restrepo

    2010-12-01

    Full Text Available This research intends to be a contribution to the Colombian sports equine medicine by providing data on electrolytes standards, a field where there is a substantial lack of literature. This research analyze and determines the normal values of sodium (Na+,potassium (K+ and ion calcium (iCa2+ electrolytes for Colombian Paso Fine horses. The establishment of the reference intervals was done at rest and after exercise. To achieve this, blood samples were taken from farms located in the Bogotá savannah. The 115 mares and stallions used for this study were actively competing with ages ranging from 43 to 78 months old. The samples were taken at three intervals: T0 (Rest,T1 (immediately after 45 minutes of exercise, and T2(1 hour post exercise. The samples were processed using a portable blood analyzer i-STAT® and the data was interpreted using descriptive and comparative statistic according to Turkey tests. The normal values for the breed were established and an electrolytic behavior curve was created, using values inside interval sat 95% confidence levels. The values obtained inmEq/L were: for T0: Na+ (136,71+/-0,23, K+ (4,05+/-0,03, Ca2+ (1,58+/-0,006; for T1: Na+ (136,44+/-0,24, K+ (3,92+/-0,24, Ca2+ (1,42+/-0,008; and for T2: Na+ (137,32+/-0,23, K+ (3,68+/-0,03, Ca2+(1,51+/-0,009. Na+ values increased after exercise. On the contrary K+ and Ca2+ values didn’t increase inT1. Calcium increased on T2 and K+ decreased. The findings of this research will serve as a framework for future analysis. Moreover, further studies and developments in this field are recommended and will prove to be very useful for equine practitioners.

  18. Biochemical and molecular characterization of an azoreductase from Staphylococcus aureus, a tetrameric NADPH-dependent flavoprotein.

    Science.gov (United States)

    Chen, Huizhong; Hopper, Sherryll L; Cerniglia, Carl E

    2005-05-01

    Azo dyes are a predominant class of colourants used in tattooing, cosmetics, foods and consumer products. A gene encoding NADPH-flavin azoreductase (Azo1) from the skin bacterium Staphylococcus aureus ATCC 25923 was identified and overexpressed in Escherichia coli. RT-PCR results demonstrated that the azo1 gene was constitutively expressed at the mRNA level in S. aureus. Azo1 was found to be a tetramer with a native molecular mass of 85 kDa containing four non-covalently bound FMN. Azo1 requires NADPH, but not NADH, as an electron donor for its activity. The enzyme was resolved to dimeric apoprotein by removing the flavin prosthetic groups using hydrophobic-interaction chromatography. The dimeric apoprotein was reconstituted on-column and in free stage with FMN, resulting in the formation of a fully functional native-like tetrameric enzyme. The enzyme cleaved the model azo dye 2-[4-(dimethylamino)phenylazo]benzoic acid (Methyl Red) into N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. The apparent Km values for NADPH and Methyl Red substrates were 0.074 and 0.057 mM, respectively. The apparent Vmax was 0.4 microM min(-1) (mg protein)(-1). Azo1 was also able to metabolize Orange II, Amaranth, Ponceau BS and Ponceau S azo dyes. Azo1 represents the first azoreductase to be identified and characterized from human skin microflora.

  19. A Tetrameric Peptide Derived from Bovine Lactoferricin Exhibits Specific Cytotoxic Effects against Oral Squamous-Cell Carcinoma Cell Lines

    Directory of Open Access Journals (Sweden)

    Víctor A. Solarte

    2015-01-01

    Full Text Available Several short linear peptides derived from cyclic bovine lactoferricin were synthesized and tested for their cytotoxic effect against the oral cavity squamous-cell carcinoma (OSCC cell lines CAL27 and SCC15. As a control, an immortalized and nontumorigenic cell line, Het-1A, was used. Linear peptides based on the RRWQWR core sequence showed a moderate cytotoxic effect and specificity towards tumorigenic cells. A tetrameric peptide, LfcinB(20–254, containing the RRWQWR motif, exhibited greater cytotoxic activity (>90% in both OSCC cell lines compared to the linear lactoferricin peptide or the lactoferrin protein. Additionally, this tetrameric peptide showed the highest specificity towards tumorigenic cells among the tested peptides. Interestingly, this effect was very fast, with cell shrinkage, severe damage to cell membrane permeability, and lysis within one hour of treatment. Our results are consistent with a necrotic effect rather than an apoptotic one and suggest that this tetrameric peptide could be considered as a new candidate for the therapeutic treatment of OSCC.

  20. Regioselectivity of enzymatic and photochemical single electron transfer promoted carbon-carbon bond fragmentation reactions of tetrameric lignin model compounds.

    Science.gov (United States)

    Cho, Dae Won; Latham, John A; Park, Hea Jung; Yoon, Ung Chan; Langan, Paul; Dunaway-Mariano, Debra; Mariano, Patrick S

    2011-04-15

    New types of tetrameric lignin model compounds, which contain the common β-O-4 and β-1 structural subunits found in natural lignins, have been prepared and carbon-carbon bond fragmentation reactions of their cation radicals, formed by photochemical (9,10-dicyanoanthracene) and enzymatic (lignin peroxidase) SET-promoted methods, have been explored. The results show that cation radical intermediates generated from the tetrameric model compounds undergo highly regioselective C-C bond cleavage in their β-1 subunits. The outcomes of these processes suggest that, independent of positive charge and odd-electron distributions, cation radicals of lignins formed by SET to excited states of sensitizers or heme-iron centers in enzymes degrade selectively through bond cleavage reactions in β-1 vs β-O-4 moieties. In addition, the findings made in the enzymatic studies demonstrate that the sterically large tetrameric lignin model compounds undergo lignin peroxidase-catalyzed cleavage via a mechanism involving preliminary formation of an enzyme-substrate complex.

  1. A novel potassium channel in photosynthetic cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Manuela Zanetti

    Full Text Available Elucidation of the structure-function relationship of a small number of prokaryotic ion channels characterized so far greatly contributed to our knowledge on basic mechanisms of ion conduction. We identified a new potassium channel (SynK in the genome of the cyanobacterium Synechocystis sp. PCC6803, a photosynthetic model organism. SynK, when expressed in a K(+-uptake-system deficient E. coli strain, was able to recover growth of these organisms. The protein functions as a potassium selective ion channel when expressed in Chinese hamster ovary cells. The location of SynK in cyanobacteria in both thylakoid and plasmamembranes was revealed by immunogold electron microscopy and Western blotting of isolated membrane fractions. SynK seems to be conserved during evolution, giving rise to a TPK (two-pore K(+ channel family member which is shown here to be located in the thylakoid membrane of Arabidopsis. Our work characterizes a novel cyanobacterial potassium channel and indicates the molecular nature of the first higher plant thylakoid cation channel, opening the way to functional studies.

  2. Elevated extracellular potassium ion concentrations suppress ...

    African Journals Online (AJOL)

    Background: Hippocampal hyperexcitability and seizure-like events have been consistently demonstrated in hippocampal slice preparations perfused with ≥ 5 mM high [K+] artificial cerebrospinal fluid (ACSF). Accordingly, high [K+] ACSF has been effectively employed as ionic model of seizure for in vitro experiments, but ...

  3. Data on electrical properties of nickel modified potassium polytitanates compacted powders

    Directory of Open Access Journals (Sweden)

    V.G. Goffman

    2015-09-01

    Full Text Available Potassium polytitanates are new promising type of ferroelectric ceramic materials with high ionic conductivity, highly polarizable structure and extremely high permittivity. Its structure is formed by [TiO6] octahedral units to layers with mobile potassium and hydroxonium ions in-between. The treatment in solutions containing nickel ions allows forming heterostructured materials which consist of potassium polytitanate particles intercalated by Ni2+ ions and/or decorated by nickel oxides NiOx. This modification route is fully dependant on solution pH, i.e. in acidic solutions the intercalation process prevails, in alkaline solutions potassium polytitanate is mostly decorated by the oxides. Therefore, electronic structure and electrical properties can be regulated depending on modification conditions, pH and ions concentration. Here we report the data on electric properties of potassium titanate modified in nickel sulfate solutions at different pH.

  4. Essential oil of Artemisia vestita exhibits potent in vitro and in vivo antibacterial activity: Investigation of the effect of oil on biofilm formation, leakage of potassium ions and survival curve measurement

    Science.gov (United States)

    YANG, CHANG; HU, DONG-HUI; FENG, YAN

    2015-01-01

    The aim of the present study was to investigate the chemical composition of the essential oil of Artemisia vestita and to determine the antibacterial activity of the essential oil and its two major components, grandisol and 1,8-cineole, against certain respiratory infection-causing bacterial strains, in vitro and in vivo. The chemical composition of the essential oil was analyzed using gas chromatography-mass spectrometry. A micro-well dilution method was used to determine the minimum inhibition concentration (MIC) values of the essential oil and its major constituents. A model of Streptococcus pyogenes infection in mice was used to determine its in vivo activities. Lung and blood samples were obtained to assess bacterial cell counts. Toxicity evaluation of the essential oil and its components was completed by performing biochemical analysis of the serum, particularly monitoring aspartate transaminase, alanine transaminase, urea and creatinine. The essential oil exhibited potent antibacterial activity, whereas the two major constituents were less potent. The essential oil exhibited MIC values between 20 and 80 μg/ml, while the values of the two constituents were between 130 and 200 μg/ml. Scanning electron microscopy results demonstrated that the essential oil inhibited biofilm formation and altered its architecture. Survival curves indicated that the essential oil led to a reduction in the viability of different bacteria. The essential oil also induced significant leakage of potassium ions from S. pyogenes. The essential oil (100 μg/mouse) and grandisol (135 μg/mouse) significantly reduced the number of viable bacterial cells in the lungs (P<0.01). However, intake of 100 μg/mouse of essential oil or grandisol 135 μg/mouse once or twice each day for 9 days did not produce any toxic effects in the mice. In conclusion, the in vitro and in vivo results suggested that the essential oil of A. vestita and one of its major constituents, grandisol, can significantly

  5. Neural synchronization via potassium signaling

    DEFF Research Database (Denmark)

    Postnov, Dmitry E; Ryazanova, Ludmila S; Mosekilde, Erik

    2006-01-01

    Using a relatively simple model we examine how variations of the extracellular potassium concentration can give rise to synchronization of two nearby pacemaker cells. With the volume of the extracellular space and the rate of potassium diffusion as control parameters, the dual nature...... junctional coupling, potassium signaling gives rise to considerable changes of the cellular response to external stimuli....

  6. Functional four-base A/T gap core sequence CATTAG of P53 response elements specifically bound tetrameric P53 differently than two-base A/T gap core sequence CATG bound both dimeric and tetrameric P53.

    Science.gov (United States)

    Cai, Bi-He; Chen, Jang-Yi; Lu, Mei-Hua; Chang, Li-Tze; Lin, Hwang-Chi; Chang, Yu-Ming; Chao, Chung-Faye

    2009-04-01

    The consensus sequence of p53 is repeated half sites of PuPuPuC(A/T)(A/T)GPyPyPy. GtAGCAttAGCCCAGACATGTCC is a 14-3-3sigma promoter p53 regulation site; the first core sequence is CAttAG, and the second is CATG. Both mutants GtAGgAttAGCCCAGACATGTCC and GtAGCAttAGCCCAGACATcTCC can be activated by p53 as a 1.5-fold half site. The original p53 regulated site on the 14-3-3sigma promoter is a whole site, and CATTAG is a functional core sequence. The p53-binding affinity and the activity of CATTAG were lower than for the mutant CATATG core sequence. Wild-type p53 acts as a tetramer to bind to the whole site; however, it also can bind to a half site by one of its dimers. Wild-type p53 can only bind to a half site with core sequence CATG but not to CATATG. The 1.5-fold half site or whole site with core sequence CATATG can be bound by wild-type p53. A p53 mutant, A344, forms dimeric p53; it can only bind to CATG, and not to CATATG. Therefore, tetrameric and dimeric p53 can bind to a two-base A/T gap core sequence, but only tetrameric p53 can bind to a four-base A/T gap core sequence.

  7. Potassium sensitivity differs among strains of the harmful cyanobacterium Microcystis and correlates with the presence of salt tolerance genes

    NARCIS (Netherlands)

    Sandrini, G.; Huisman, J.; Matthijs, H.C.P.

    2015-01-01

    Microcystis aeruginosa is a ubiquitous harmful cyanobacterium that causes problems in eutrophic lakes. Potassium ion (K+) addition is one of the suggested methods to combat harmful cyanobacterial blooms. To investigate the effectiveness of this method, we compared the potassium ion sensitivity of

  8. Role of inward rectifier potassium channels in salivary gland function and sugar feeding of the fruit fly, Drosophila melanogaster

    Science.gov (United States)

    The arthropod salivary gland is of critical importance for horizontal transmission of pathogens, yet a detailed understanding of the ion conductance pathways responsible for saliva production and excretion is lacking. A superfamily of potassium ion channels, known as inward rectifying potassium (Ki...

  9. Isolation of dimeric, trimeric, tetrameric and pentameric procyanidins from unroasted cocoa beans (Theobroma cacao L.) using countercurrent chromatography.

    Science.gov (United States)

    Esatbeyoglu, Tuba; Wray, Victor; Winterhalter, Peter

    2015-07-15

    The main procyanidins, including dimeric B2 and B5, trimeric C1, tetrameric and pentameric procyanidins, were isolated from unroasted cocoa beans (Theobroma cacao L.) using various techniques of countercurrent chromatography, such as high-speed countercurrent chromatography (HSCCC), low-speed rotary countercurrent chromatography (LSRCCC) and spiral-coil LSRCCC. Furthermore, dimeric procyanidins B1 and B7, which are not present naturally in the analysed cocoa beans, were obtained after semisynthesis of cocoa bean polymers with (+)-catechin as nucleophile and separated by countercurrent chromatography. In this way, the isolation of dimeric procyanidin B1 in considerable amounts (500mg, purity>97%) was possible in a single run. This is the first report concerning the isolation and semisynthesis of dimeric to pentameric procyanidins from T. cacao by countercurrent chromatography. Additionally, the chemical structures of tetrameric (cinnamtannin A2) and pentameric procyanidins (cinnamtannin A3) were elucidated on the basis of (1)H NMR spectroscopy. Interflavanoid linkage was determined by NOE-correlations, for the first time. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Potassium channel family in giant motor axons of Aglantha digitale.

    Science.gov (United States)

    Meech, R W; Mackie, G O

    1993-03-01

    1. The simplicity of the jellyfish nervous system makes it an ideal preparation to assess the contributions of different ion channels to behavior. In the giant motor axons of the jellyfish Aglantha digitale, low-threshold spikes elicit slow swimming, whereas escape swimming depends on a higher-threshold, overshooting sodium-dependent action potential. At least three kinetically distinct transient potassium channels (fast, intermediate, and slow) are concerned with spike management in this preparation. 2. In situ recording with patch-clamp micropipettes from clusters of potassium channels provides a means of studying their properties in isolation. The three classes of ion channel were identified in ensemble current averages by their kinetics, their response to a conditioning prepulse and their voltage dependence. All three were highly selective for potassium, and the reversal potential of their unitary currents depended on the level of potassium used to fill the patch pipette. 3. A single potassium permeability coefficient (PK) calculated from the Goldman, Hodgkin, Katz "constant field" equation was used to fit unitary current data from all three channels in concentrations of external potassium < or = 500 mM. 4. Data from ensemble tail currents in seawater indicated that the sodium permeability coefficient (PNa) of channels with either intermediate or slow kinetics was < or = 0.015 PK; preliminary data from channels with fast kinetics suggested that they too had a PNa/PK selectivity of approximately 0.01. 5. We propose that spike management in the giant motor axons of Aglantha depends on three members of a family of potassium-selective ion channels that seem likely to be structurally related.

  11. Cloning and expression analysis of potassium channel gene NKT3 ...

    African Journals Online (AJOL)

    Potassium (K+) is the predominant inorganic ion of plant cells. K+ channels in higher plant cells play an important role in regulating the influx and efflux of K+ from cells, and activity of these channels might be involved in plant stress resistance. A completely new K+ channel gene of Nicotiana tabacum was obtained through ...

  12. Monomeric, trimeric, and tetrameric transition metal complexes (Mn, Fe, Co) containing N,N-bis(2-pyridylmethyl)-2-aminoethanol/-ate: preparation, crystal structure, molecular magnetism and oxidation catalysis.

    Science.gov (United States)

    Shin, Jong Won; Rowthu, Sankara Rao; Hyun, Min Young; Song, Young Joo; Kim, Cheal; Kim, Bong Gon; Min, Kil Sik

    2011-06-07

    The reaction of N,N-bis(2-pyridylmethyl)-2-aminoethanol (bpaeOH), NaSCN/NaN(3), and metal (M) ions [M = Mn(II), Fe(II/III), Co(II)] in MeOH, leads to the isolation of a series of monomeric, trimeric, and tetrameric metal complexes, namely [Mn(bpaeOH)(NCS)(2)] (1), [Mn(bpaeO)(N(3))(2)] (2), [Fe(bpaeOH)(NCS)(2)] (3), [Fe(4)(bpaeO)(2)(CH(3)O)(2)(N(3))(8)] (4), [Co(bpaeOH)(NCS)(2)] (5), and [Co(3)(bpaeO)(2)(NO(3))(N(3))(4)](NO(3)) (6). These compounds have been investigated by single crystal X-ray diffractometry and magnetochemistry. In complex 1 the Mn(II) is bonded to one bpaeOH and two thiocyanate ions, while in complex 2 it is coordinated to a deprotonated bpaeO(-) and two azide ions. The oxidation states of manganese ions are 2+ for 1 and 3+ for 2, respectively, indicating that the different oxidation states depend on the type of binding anions. The structures of monomeric iron(II) and cobalt(II) complexes 3 and 5 with two thiocyanate ions are isomorphous to that of 1. Compounds 1, 2, 3, and 5 exhibit high-spin states in the temperature range 5 to 300 K. 4 contains two different iron(III) ions in an asymmetric unit, one is coordinated to a deprotonated bpaeO(-), an azide ion, and a methoxy group, and the other is bonded to three azide ions and two oxygens from bpaeO(-) and a methoxy group. Two independent iron(III) ions in 4 form a tetranuclear complex by symmetry. 4 displays both ferromagnetic and antiferromagnetic couplings (J = 9.8 and -14.3 cm(-1)) between the iron(III) ions. 6 is a mixed-valence trinuclear cobalt complex, which is formulated as Co(III)(S = 0)-Co(II)(S = 3/2)-Co(III)(S = 0). The effective magnetic moment at room temperature corresponds to the high-spin cobalt(II) ion (∼4.27 μ(B)). Interestingly, 6 showed efficient catalytic activities toward various olefins and alcohols with modest to excellent yields, and it has been proposed that a high-valent Co(V)-oxo species might be responsible for oxygen atom transfer in the olefin epoxidation and

  13. PET imaging of alpha(v)beta(3) integrin expression in tumours with Ga-68-labelled mono-, di- and tetrameric RGD peptides

    NARCIS (Netherlands)

    Dijkgraaf, Ingrid; Yim, Cheng-Bin; Franssen, Gerben M.; Schuit, Robert C.; Luurtsema, Gert; Liu, Shuang; Oyen, Wim J. G.; Boerman, Otto C.

    Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3)-binding characteristics of Ga-68-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared with their

  14. Dietary reference values for potassium

    DEFF Research Database (Denmark)

    Sjödin, Anders Mikael

    2016-01-01

    Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derives dietary reference values (DRVs) for potassium. The Panel decides to set DRVs on the basis of the relationships between potassium intake and blood pressure and stroke...

  15. Potassium supplementation and heart rate

    NARCIS (Netherlands)

    Gijsbers, L.; Molenberg, Famke; Bakker, S.J.L.; Geleijnse, J.M.

    2016-01-01

    Background and aims: Increasing the intake of potassium has been shown to lower blood pressure, but whether it also affects heart rate (HR) is largely unknown. We therefore assessed the effect of potassium supplementation on HR in a meta-analysis of randomized controlled trials. Methods and

  16. Transformation of potassium Lindquist hexaniobate to various potassium niobates: solvothermal synthesis and structural evolution mechanism.

    Science.gov (United States)

    Kong, Xingang; Hu, Dengwei; Wen, Puhong; Ishii, Tomohiko; Tanaka, Yasuhiro; Feng, Qi

    2013-06-07

    This paper introduces the formation reactions and reaction mechanisms of a series of potassium niobates from a potassium salt of the Lindquist hexaniobate [Nb6O19](8-) ion under solvothermal conditions. The structure and particle morphology of the potassium niobate product can be controlled easily with the reaction solution alkalinity using this solvothermal process. KNb3O8 with a plate-like morphology, K4Nb6O17·4.5H2O with a plate-like morphology, a new phase of K2Nb2O6·H2O with fibrous morphology, KNbO3 perovskites with cubic morphology are obtained at pH = 5.5, and in 0.3, 0.5, 1.0 mol L(-1) KOH solutions at 230 °C, respectively. The reaction conditions are much milder than those in the normal hydrothermal process. Furthermore, the K2Nb2O6·H2O fibers can be topotactically transformed into KNbO3 fibers, Nb2O5 fibers after H(+)-exchange-treatment, and LiNbO3 fibers after Li(+)-exchange-treatment by heat-treatments at 730, 560, and 520 °C, respectively. The formation reaction and structure of these potassium niobates were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), energy-dispersive spectroscopy (EDS), Raman spectra and TG-DTA. The formation mechanism of this series of potassium niobates from the [Nb6O19](8-) precursor is systematically explained via the correlation between the octahedrons [NbO6] sharing forms in the precursor structure and in the product structures.

  17. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter

    2014-01-01

    About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...... drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate...... that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K(+) channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure...

  18. Genetic disorders of potassium homeostasis.

    Science.gov (United States)

    Jain, Gaurav; Ong, Song; Warnock, David G

    2013-05-01

    Hereditary disorders of potassium homeostasis are an interesting group of disorders, affecting people from the newborn period to adults of all ages. The clinical presentation varies from severe hypotension at birth to uncontrolled hypertension in adults, often associated with abnormal potassium values, although many patients may have a normal serum potassium concentration despite being affected by the genetic disorder. A basic understanding of these disorders and their underlying mechanisms has significant clinical implications, especially in the few patients with subtle clinical signs and symptoms. We present a summary of these disorders, with emphasis on the clinical presentation and genetic mechanisms of these disorders. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Interactive effects of salinity and low potassium on growth, physiology response of Houttuynia cordata Thunb. W01-100

    OpenAIRE

    Zou Y. T.; Dai S.; Li J. Y.; Liu Z. Q.; Wu W.

    2012-01-01

    Houttuynia cordata Thunb. is a plant enrichment in potassium in plant was reported. Salinity and low potassium availability are important environmental factors restricting plant growth and productivity throughout the world. The interactive effects of salinity and potassium on growth, water content, chlorophyll content, lipid peroxidation content, ion accumulations and K+/Na+ ratio, and organic accumulations as well as oxidative enzymes were investigated in Houttuynia cordata Thunb.. Plants ...

  20. Potassium Channels in Neurofbromatosis-1

    National Research Council Canada - National Science Library

    Chen, Mingkui

    2006-01-01

    .... We were the first to investigate potential mechanisms of cognitive impairment in NF-1 at the molecular level involving potassium channels, and demonstrated a possible mechanism for the learning deficits seen in NF1...

  1. Preparation of Potassium Ferrate from Spent Steel Pickling Liquid

    Directory of Open Access Journals (Sweden)

    Yu-Ling Wei

    2015-09-01

    Full Text Available Potassium ferrate (K2FeO4 is a multi-functional green reagent for water treatment with considerable combined effectiveness in oxidization, disinfection, coagulation, sterilization, adsorption, and deodorization, producing environment friendly Fe(III end-products during the reactions. This study uses a simple method to lower Fe(VI preparation cost by recycling iron from a spent steel pickling liquid as an iron source for preparing potassium ferrate with a wet oxidation method. The recycled iron is in powder form of ferrous (93% and ferric chlorides (7%, as determined by X-ray Absorption Near Edge Spectrum (XANES simulation. The synthesis method involves three steps, namely, oxidation of ferrous/ferric ions to form ferrate with NaOCl under alkaline conditions, substitution of sodium with potassium to form potassium ferrate, and continuously washing impurities with various organic solvents off the in-house ferrate. Characterization of the in-house product with various instruments, such as scanning electron microscopy (SEM, ultraviolet-visible (UV-Vis, X-ray diffraction (XRD, and X-ray absorption spectroscopy (XAS, proves that product quality and purity are comparative to a commercialized one. Methylene blue (MB de-colorization tests with in-house potassium ferrate shows that, within 30 min, almost all MB molecules are de-colorized at a Fe/carbon mole ratio of 2/1.

  2. 21 CFR 184.1610 - Potassium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No... algae. Potassium alginate is prepared by the neutralization of purified alginic acid with appropriate pH...

  3. Nematode parasites of the Chilean Flamingo, Phoenicopterus chilensis (Phoenicopteridae) from Central Argentina, with a description of a new species of Tetrameres (Tetrameridae).

    Science.gov (United States)

    Núñez, Verónica; Drago, Fabiana B; Digiani, María Celina; Lunaschi, Lia I

    2017-06-01

    During the summer of 2013, several specimens of Phoenicopterus chilensis (Phoenicopteridae) were found dead from unknown causes, in lakes from the endorheic system "Encadenadas del Oeste", Buenos Aires Province, Argentina. Two species of Nematoda were recovered from the proventriculus, one of them new for science. The tetramerid Tetrameres (Tetrameres) salina n. sp. is mainly characterized by having reduced pseudolabia, lips absent, six bifid teeth, males with lateral alae, four rows of somatic spines and length ratio of spicules 1:12-32, and large females with eggs lacking polar filaments. The acuariid, Echinuria skrjabinensis is described and illustrated, this finding represent the second report of this nematode in Argentina and the first record in flamingos. This is the first record of helminths parasitizing wild Chilean Flamingos, but it is not possible to ensure that they accomplish their life cycle in this system of lakes, because the migratory movements of the population of flamingos studied are unknown.

  4. The Vip3Ag4 Insecticidal Protoxin from Bacillus thuringiensis Adopts A Tetrameric Configuration That Is Maintained on Proteolysis

    Directory of Open Access Journals (Sweden)

    Leopoldo Palma

    2017-05-01

    Full Text Available The Vip3 proteins produced during vegetative growth by strains of the bacterium Bacillus thuringiensis show insecticidal activity against lepidopteran insects with a mechanism of action that may involve pore formation and apoptosis. These proteins are promising supplements to our arsenal of insecticidal proteins, but the molecular details of their activity are not understood. As a first step in the structural characterisation of these proteins, we have analysed their secondary structure and resolved the surface topology of a tetrameric complex of the Vip3Ag4 protein by transmission electron microscopy. Sites sensitive to proteolysis by trypsin are identified and the trypsin-cleaved protein appears to retain a similar structure as an octomeric complex comprising four copies each of the ~65 kDa and ~21 kDa products of proteolysis. This processed form of the toxin may represent the active toxin. The quality and monodispersity of the protein produced in this study make Vip3Ag4 a candidate for more detailed structural analysis using cryo-electron microscopy.

  5. A Novel Fucose-binding Lectin from Photorhabdus luminescens (PLL) with an Unusual Heptabladed β-Propeller Tetrameric Structure.

    Science.gov (United States)

    Kumar, Atul; Sýkorová, Petra; Demo, Gabriel; Dobeš, Pavel; Hyršl, Pavel; Wimmerová, Michaela

    2016-11-25

    Photorhabdus luminescens is known for its symbiosis with the entomopathogenic nematode Heterorhabditis bacteriophora and its pathogenicity toward insect larvae. A hypothetical protein from P. luminescens was identified, purified from the native source, and characterized as an l-fucose-binding lectin, named P. luminescens lectin (PLL). Glycan array and biochemical characterization data revealed PLL to be specific toward l-fucose and the disaccharide glycan 3,6-O-Me2-Glcβ1-4(2,3-O-Me2)Rhaα-O-(p-C6H4)-OCH2CH2NH2 PLL was discovered to be a homotetramer with an intersubunit disulfide bridge. The crystal structures of native and recombinant PLL revealed a seven-bladed β-propeller fold creating seven putative fucose-binding sites per monomer. The crystal structure of the recombinant PLL·l-fucose complex confirmed that at least three sites were fucose-binding. Moreover, the crystal structures indicated that some of the other sites are masked either by the tetrameric nature of the lectin or by incorporation of the C terminus of the lectin into one of these sites. PLL exhibited an ability to bind to insect hemocytes and the cuticular surface of a nematode, H. bacteriophora. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Structure of rhamnose-binding lectin CSL3: unique pseudo-tetrameric architecture of a pattern recognition protein.

    Science.gov (United States)

    Shirai, Tsuyoshi; Watanabe, Yasuharu; Lee, Min-sub; Ogawa, Tomohisa; Muramoto, Koji

    2009-08-14

    The crystal structure of the L-rhamnose-binding lectin CSL3 was determined to 1.8 A resolution. This protein is a component of the germline-encoded pattern recognition proteins in innate immunity. CSL3 is a homodimer of two 20 kDa subunits with a dumbbell-like shape overall, in which the N- and C-terminal domains of different subunits form lobe structures connected with flexible linker peptides. The complex structures of the protein with specific carbohydrates demonstrated the importance of the most variable loop region among homologues for the specificity toward oligosaccharides. CSL3 and Shiga-like toxin both use Gb(3) as a cellular receptor to evoke apoptosis. They have very different overall architecture but share the separation distance between carbohydrate-binding sites. An inspection of the structure database suggested that the pseudo-tetrameric structure of CSL3 was unique among the known lectins. This architecture implies this protein might provide a unique tool for further investigations into the relationships between architecture and function of pattern recognition proteins.

  7. Understanding ternary poly(potassium benzimidazolide)-based polymer electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Jankova Atanasova, Katja; Han, Junyoung

    2016-01-01

    in fuel cell catalyst layers. This work focuses on the chemistry of m-PBI in aqueous potassium hydroxide. Equilibration in aqueous KOH with concentrations of 15e20 wt.% was found to result in ionization of the polymer, causing released intermolecular hydrogen bonding. This allowed for extensive volume......Poly(2,20-(m-phenylene)-5,50-bisbenzimidazole) (m-PBI) can dissolve large amounts of aqueous electrolytes to give materials with extraordinary high ion conductivity and the practical applicability has been demonstrated repeatedly in fuel cells, water electrolysers and as anion conducting component...... swelling, high electrolyte uptake, dramatic plasticization and increase of the ion conductivity for the formed poly(potassium benzimidazolide)-based structure. Further increasing the concentration of the bulk solution to 50 wt.% resulted in dehydration and extensive crystallization of the polymer matrix...

  8. Understanding ternary poly(potassium benzimidazolide)-based polymer electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Jankova Atanasova, Katja; Han, Junyoung

    2016-01-01

    in fuel cell catalyst layers. This work focuses on the chemistry of m-PBI in aqueous potassium hydroxide. Equilibration in aqueous KOH with concentrations of 15e20 wt.% was found to result in ionization of the polymer, causing released intermolecular hydrogen bonding. This allowed for extensive volume...... swelling, high electrolyte uptake, dramatic plasticization and increase of the ion conductivity for the formed poly(potassium benzimidazolide)-based structure. Further increasing the concentration of the bulk solution to 50 wt.% resulted in dehydration and extensive crystallization of the polymer matrix......Poly(2,20-(m-phenylene)-5,50-bisbenzimidazole) (m-PBI) can dissolve large amounts of aqueous electrolytes to give materials with extraordinary high ion conductivity and the practical applicability has been demonstrated repeatedly in fuel cells, water electrolysers and as anion conducting component...

  9. A regenerable potassium and phosphate sorbent system to enhance dialysis efficacy and device portability : A study in awake goats

    NARCIS (Netherlands)

    Wester, Maarten; Gerritsen, Karin G.|info:eu-repo/dai/nl/31398512X; Simonis, Frank|info:eu-repo/dai/nl/413981320; Boer, Walther H.|info:eu-repo/dai/nl/07321650X; Hazenbrink, Dienty H. M.; Vaessen, Koen R.; Verhaar, Marianne C.|info:eu-repo/dai/nl/182921840; Joles, Jaap A.|info:eu-repo/dai/nl/070114595

    2017-01-01

    Background: Patients on standard intermittent haemodialysis suffer from strong fluctuations in plasma potassium and phosphate. Prolonged dialysis with a wearable device, based on continuous regeneration of a small volume of dialysate using ion exchangers, could moderate these fluctuations and offer

  10. PET imaging of αvβ₃ integrin expression in tumours with ⁶⁸Ga-labelled mono-, di- and tetrameric RGD peptides.

    Science.gov (United States)

    Dijkgraaf, Ingrid; Yim, Cheng-Bin; Franssen, Gerben M; Schuit, Robert C; Luurtsema, Gert; Liu, Shuang; Oyen, Wim J G; Boerman, Otto C

    2011-01-01

    Due to the restricted expression of α(v)β(3) in tumours, α(v)β(3) is considered a suitable receptor for tumour targeting. In this study the α(v)β(3)-binding characteristics of (68)Ga-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared with their (111)In-labelled counterparts. A monomeric (E-c(RGDfK)), a dimeric (E-[c(RGDfK)](2)) and a tetrameric (E{E[c(RGDfK)](2)}(2)) RGD peptide were synthesised, conjugated with DOTA and radiolabelled with (68)Ga. In vitro α(v)β(3)-binding characteristics were determined in a competitive binding assay. In vivo α(v)β(3)-targeting characteristics of the compounds were assessed in mice with subcutaneously growing SK-RC-52 xenografts. In addition, microPET images were acquired using a microPET/CT scanner. The IC(50) values for the Ga(III)-labelled DOTA-E-c(RGDfK), DOTA-E-[c(RGDfK)](2) and DOTA-E{E[c(RGDfK)](2)}(2) were 23.9 ± 1.22, 8.99 ± 1.20 and 1.74 ± 1.18 nM, respectively, and were similar to those of the In(III)-labelled mono-, di- and tetrameric RGD peptides (26.6 ± 1.15, 3.34 ± 1.16 and 1.80 ± 1.37 nM, respectively). At 2 h post-injection, tumour uptake of the (68)Ga-labelled mono-, di- and tetrameric RGD peptides (3.30 ± 0.30, 5.24 ± 0.27 and 7.11 ± 0.67%ID/g, respectively) was comparable to that of their (111)In-labelled counterparts (2.70 ± 0.29, 5.61 ± 0.85 and 7.32 ± 2.45%ID/g, respectively). PET scans were in line with the biodistribution data. On all PET scans, the tumour could be clearly visualised. The integrin affinity and the tumour uptake followed the order of DOTA-tetramer > DOTA-dimer > DOTA-monomer. The (68)Ga-labelled tetrameric RGD peptide has excellent characteristics for imaging of α(v)β(3) expression with PET.

  11. PET imaging of {alpha}{sub v}{beta}{sub 3} integrin expression in tumours with {sup 68}Ga-labelled mono-, di- and tetrameric RGD peptides

    Energy Technology Data Exchange (ETDEWEB)

    Dijkgraaf, Ingrid; Franssen, Gerben M.; Oyen, Wim J.G.; Boerman, Otto C. [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Yim, Cheng-Bin [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Utrecht University, Department of Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht (Netherlands); Schuit, Robert C. [VU University Medical Centre, Department of Nuclear Medicine and PET Research, P.O. Box 7057, Amsterdam (Netherlands); Luurtsema, Gert [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Hanzeplein 1, P.O. Box 30.001, Groningen (Netherlands); Liu, Shuang [Purdue University, School of Health Sciences, West Lafayette, IN (United States)

    2011-01-15

    Due to the restricted expression of {alpha}{sub v}{beta}{sub 3} in tumours, {alpha}{sub v}{beta}{sub 3} is considered a suitable receptor for tumour targeting. In this study the {alpha}{sub v}{beta}{sub 3}-binding characteristics of {sup 68}Ga-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared with their {sup 111}In-labelled counterparts. A monomeric (E-c(RGDfK)), a dimeric (E-[c(RGDfK)]{sub 2}) and a tetrameric (E{l_brace}E[c(RGDfK)]{sub 2}{r_brace}{sub 2}) RGD peptide were synthesised, conjugated with DOTA and radiolabelled with {sup 68}Ga. In vitro {alpha}{sub v}{beta}{sub 3}-binding characteristics were determined in a competitive binding assay. In vivo {alpha}{sub v}{beta}{sub 3}-targeting characteristics of the compounds were assessed in mice with subcutaneously growing SK-RC-52 xenografts. In addition, microPET images were acquired using a microPET/CT scanner. The IC{sub 50} values for the Ga(III)-labelled DOTA-E-c(RGDfK), DOTA-E-[c(RGDfK)]{sub 2} and DOTA-E{l_brace}E[c(RGDfK)]{sub 2}{r_brace}{sub 2} were 23.9 {+-} 1.22, 8.99 {+-} 1.20 and 1.74 {+-} 1.18 nM, respectively, and were similar to those of the In(III)-labelled mono-, di- and tetrameric RGD peptides (26.6 {+-} 1.15, 3.34 {+-} 1.16 and 1.80 {+-} 1.37 nM, respectively). At 2 h post-injection, tumour uptake of the {sup 68}Ga-labelled mono-, di- and tetrameric RGD peptides (3.30 {+-} 0.30, 5.24 {+-} 0.27 and 7.11 {+-} 0.67%ID/g, respectively) was comparable to that of their {sup 111}In-labelled counterparts (2.70 {+-} 0.29, 5.61 {+-} 0.85 and 7.32 {+-} 2.45%ID/g, respectively). PET scans were in line with the biodistribution data. On all PET scans, the tumour could be clearly visualised. The integrin affinity and the tumour uptake followed the order of DOTA-tetramer > DOTA-dimer > DOTA-monomer. The {sup 68}Ga-labelled tetrameric RGD peptide has excellent characteristics for imaging of {alpha}{sub v} {beta}{sub 3} expression with PET. (orig.)

  12. Development of novel nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric

    OpenAIRE

    Bondar, Yuliia; Kuzenko, Svetlana; Han, Do-Hung; Cho, Hyun-Kug

    2014-01-01

    A nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric was synthesized for selective removal of Cs ions from contaminated waters by a two-stage synthesis: radiation-induced graft polymerization of acrylic acid monomer onto the nonwoven polypropylene fabric surface with subsequent in situ formation of potassium nickel hexacyanoferrate (KNiHCF) nanoparticles within the grafted chains. Data of scanning electron microscopy, X-ray diffraction, and Fourier ...

  13. Determination of metastable zone width of potassium sulfate in aqueous solution by ultrasonic sensor and FBRM

    Science.gov (United States)

    Luo, Mengjie; Liu, Chenglin; Xue, Jin; Li, Ping; Yu, Jianguo

    2017-07-01

    The metastable zone width (MSZW) and nucleation kinetics of potassium sulfate in the aqueous solution were investigated. MSZW was measured using both the ultrasonic velocity sensor and the focused beam reflectance measurement (FBRM) at different cooling rate, stirring rate and impurities concentration (aluminum ions and silicon ions), and the effects of these conditions on MSZW were discussed in details. In addition, the accuracy and sensitivity of detectors to measure the nucleation temperature of potassium sulfate in the aqueous solution were compared between the ultrasonic velocity sensor and FBRM over a wider range of operating conditions. Although two detectors measured MSZW with an acceptable accuracy, the ultrasonic velocity sensor had a higher sensitivity to the phase transition of potassium sulfate in solution since it directly detected the concentration change of potassium sulfate in solution. Furthermore, both self-consistent Nývlt-like equation method and classical 3D nucleation theory approach were applied to estimate MSZW of potassium sulfate in aqueous solution. According to these classical theories, the nucleation kinetics parameters were calculated based on the measured MSZW data for potassium sulfate aqueous solution with 40 °C, 50 °C and 60 °C saturation temperature, respectively. It was found two approaches could describe MSZW of potassium sulfate aqueous system very well.

  14. Structure and Mechanism of Proton Transport Through the Transmembrane Tetrameric M2 Protein Bundle of the Influenza A Virus

    Energy Technology Data Exchange (ETDEWEB)

    R Acharya; V Carnevale; G Fiorin; B Levine; A Polishchuk; V Balannick; I Samish; R Lamb; L Pinto; et al.

    2011-12-31

    The M2 proton channel from influenza A virus is an essential protein that mediates transport of protons across the viral envelope. This protein has a single transmembrane helix, which tetramerizes into the active channel. At the heart of the conduction mechanism is the exchange of protons between the His37 imidazole moieties of M2 and waters confined to the M2 bundle interior. Protons are conducted as the total charge of the four His37 side chains passes through 2{sup +} and 3{sup +} with a pK{sub a} near 6. A 1.65 {angstrom} resolution X-ray structure of the transmembrane protein (residues 25-46), crystallized at pH 6.5, reveals a pore that is lined by alternating layers of sidechains and well-ordered water clusters, which offer a pathway for proton conduction. The His37 residues form a box-like structure, bounded on either side by water clusters with well-ordered oxygen atoms at close distance. The conformation of the protein, which is intermediate between structures previously solved at higher and lower pH, suggests a mechanism by which conformational changes might facilitate asymmetric diffusion through the channel in the presence of a proton gradient. Moreover, protons diffusing through the channel need not be localized to a single His37 imidazole, but instead may be delocalized over the entire His-box and associated water clusters. Thus, the new crystal structure provides a possible unification of the discrete site versus continuum conduction models.

  15. EAG2 potassium channel with evolutionarily conserved function as a brain tumor target

    Science.gov (United States)

    Huang, Xi; He, Ye; Dubuc, Adrian M.; Hashizume, Rintaro; Zhang, Wei; Reimand, Jüri; Yang, Huanghe; Wang, Tongfei A.; Stehbens, Samantha J.; Younger, Susan; Barshow, Suzanne; Zhu, Sijun; Cooper, Michael K.; Peacock, John; Ramaswamy, Vijay; Garzia, Livia; Wu, Xiaochong; Remke, Marc; Forester, Craig M.; Kim, Charles C.; Weiss, William A.; James, C. David; Shuman, Marc A.; Bader, Gary D.; Mueller, Sabine; Taylor, Michael D.; Jan, Yuh Nung; Jan, Lily Yeh

    2015-01-01

    Over 20% of the drugs for treating human diseases target ion channels, however, no cancer drug approved by the U.S. Food and Drug Administration (FDA) is intended to target an ion channel. Here, we demonstrate the evolutionarily conserved function of EAG2 potassium channel in promoting brain tumor growth and metastasis, delineate downstream pathways and uncover a mechanism for different potassium channels to functionally corporate and regulate mitotic cell volume and tumor progression. We show that EAG2 potassium channel is enriched at the trailing edge of migrating MB cells to regulate local cell volume dynamics, thereby facilitating cell motility. We identify the FDA-approved antipsychotic drug thioridazine as an EAG2 channel blocker that reduces xenografted MB growth and metastasis, and present a case report of repurposing thioridazine for treating a human patient. Our findings thus illustrate the potential of targeting ion channels in cancer treatment. PMID:26258683

  16. Can Diuretics Decrease Your Potassium Level?

    Science.gov (United States)

    Diseases and Conditions High blood pressure (hypertension) Can diuretics decrease your potassium level? Answers from Sheldon G. Sheps, M.D. Yes, some diuretics — also called water pills — decrease potassium in the ...

  17. Radiation dosimetry by potassium feldspar

    Indian Academy of Sciences (India)

    Unknown

    Radiation dosimetry by potassium feldspar. ARUN PANDYA*, S G VAIJAPURKAR and P K BHATNAGAR. Defence Laboratory, Jodhpur 342 011, India. MS received 12 July 1999; revised 15 February 2000. Abstract. The thermoluminescence (TL) properties of raw and annealed feldspar have been studied for their.

  18. Increased serum potassium affects renal outcomes

    DEFF Research Database (Denmark)

    Miao, Y; Dobre, D; Heerspink, H J Lambers

    2011-01-01

    To assess the effect of an angiotensin receptor blocker (ARB) on serum potassium and the effect of a serum potassium change on renal outcomes in patients with type 2 diabetes and nephropathy.......To assess the effect of an angiotensin receptor blocker (ARB) on serum potassium and the effect of a serum potassium change on renal outcomes in patients with type 2 diabetes and nephropathy....

  19. 21 CFR 582.7610 - Potassium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is generally...

  20. 21 CFR 582.1613 - Potassium bicarbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium bicarbonate. 582.1613 Section 582.1613 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1613 Potassium bicarbonate. (a) Product. Potassium bicarbonate. (b) Conditions of use. This...

  1. 21 CFR 184.1613 - Potassium bicarbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium bicarbonate. 184.1613 Section 184.1613... Listing of Specific Substances Affirmed as GRAS § 184.1613 Potassium bicarbonate. (a) Potassium bicarbonate (KHCO3, CAS Reg. No. 298-14-6) is made by the following processes: (1) By treating a solution of...

  2. 21 CFR 172.730 - Potassium bromate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium bromate. 172.730 Section 172.730 Food and... Specific Usage Additives § 172.730 Potassium bromate. The food additive potassium bromate may be safely... malt from the treatment does not exceed 75 parts per million of bromate (calculated as Br), and the...

  3. Thanatochemistry: Study of vitreous humor potassium | Tumram ...

    African Journals Online (AJOL)

    This study has been carried out to determine the death interval from the biochemical parameter of vitreous potassium. In 308 medicolegal cases vitreous humor was taken and analyzed for potassium with known time of death. There was a linear rise in potassium concentration with increasing death interval. Regression ...

  4. Response of silicon position sensitive detectors to heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Read, P.M.; Rotberg, V.H. (UKAEA Atomic Energy Research Establishment, Harwell. Nuclear Physics Div.); Tolfree, D.W.L.; Groves, J. (Science Research Council, Daresbury (UK). Daresbury Lab.)

    1983-01-15

    The pulse height response characteristics of surface barrier and ion implanted position sensitive detectors have been measured. Surface barrier detectors with junctions formed using oxidation by potassium dichromate exhibit small heavy ion pulse height defects indicating thin entrance windows. Ion implanted detectors give considerably larger defects because of penetrating tails in the distribution of implanted ions and electrically active defects.

  5. The response of silicon position sensitive detectors to heavy ions

    Science.gov (United States)

    Read, P. M.; Rotberg, V. H.; Tolfree, D. W. L.; Groves, J.

    1983-01-01

    The pulse height response characteristics of surface barrier and ion implanted position sensitive detectors have been measured. Surface barrier detectors with junctions formed using oxidation by potassium dichromate exhibit small heavy ion pulse height defects indicating thin entrance windows. Ion implanted detectors give considerably larger defects because of penetrating tails in the distribution of implanted ions and electrically active defects.

  6. Crystal structure of the tetrameric fibrinogen-like recognition domain of Fibrinogen C domain containing 1 (FIBCD1)

    DEFF Research Database (Denmark)

    Shrive, Annette K; Moeller, Jesper B; Burns, Ian

    2014-01-01

    site and a sulphate ion has been placed adjacent to this site. These ion binding sites are ideally placed to receive the N-acetyl and sulphate groups of sulphated GalNAc residues of glycosaminoglycans such as chondroitin and dermatan sulphate. Together, these structures give insight into important....... In the ligand bound structure this GlcNAc is replaced by the higher affinity ligand ManNAc. In addition, a sulphate ion has been modelled into the electron density at a location similar to the S3 binding site in L-ficolin, while in the native structure an acetate ion has been placed in the S1 N-acetyl binding...

  7. The constant value of the total concentration of potassium and sodium in tissue water in animals.

    Science.gov (United States)

    Schillak, R

    1978-01-01

    With age, the Musculus longissimus dorsi in pigs showed an increase in the potassium content and a decrease in the sodium content. The total concentration of potassium and sodium in milimoles in one litre of tissue water, here referred to as the "Sum k", is a constant value. The same mean Sum k had been obtained earlier by Blaxter and Rook for various kinds of tissue in cattle of different age. Approximate mean Sums k were calculated from the water, potassium and sodium contents in the muscles of man and pig at different stages of development, as reported in another publication. The constant character of Sum k was shown to be due to the equal concentration of potassium and sodium ions. This allows to calculate the quantity of water in the tissue from the potassium and sodium ions it contains and the percentage of extracellular or cellular water in total water. A consideration of the relationship between Sum k and osmotic pressure in the tissues proved an absence of concentration symmetry between the cellular and extracellular fluids which Sum k had seemed to suggest. Consequently, the total potassium content was multiplied by the asymmetry coefficient, fK, and then the Sum kc = mM (FKK + Na) per litre of water. From Blaxter and Rook's equation it was calculated that fK = 0.856 and Sum kc 148.8 mM.

  8. Crystal structure of the potassium-importing KdpFABC membrane complex

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ching-Shin; Pedersen, Bjørn Panyella; Stokes, David L.

    2017-06-21

    Cellular potassium import systems play a fundamental role in osmoregulation, pH homeostasis and membrane potential in all domains of life. In bacteria, the kdp operon encodes a four-subunit potassium pump that maintains intracellular homeostasis, cell shape and turgor under conditions in which potassium is limiting1. This membrane complex, called KdpFABC, has one channel-like subunit (KdpA) belonging to the superfamily of potassium transporters and another pump-like subunit (KdpB) belonging to the superfamily of P-type ATPases. Although there is considerable structural and functional information about members of both superfamilies, the mechanism by which uphill potassium transport through KdpA is coupled with ATP hydrolysis by KdpB remains poorly understood. Here we report the 2.9 Å X-ray structure of the complete Escherichia coli KdpFABC complex with a potassium ion within the selectivity filter of KdpA and a water molecule at a canonical cation site in the transmembrane domain of KdpB. The structure also reveals two structural elements that appear to mediate the coupling between these two subunits. Specifically, a protein-embedded tunnel runs between these potassium and water sites and a helix controlling the cytoplasmic gate of KdpA is linked to the phosphorylation domain of KdpB. On the basis of these observations, we propose a mechanism that repurposes protein channel architecture for active transport across biomembranes.

  9. Preliminary X-ray crystallographic studies of a tetrameric phospholipase A{sub 2} formed by two isoforms of crotoxin B from Crotalus durissus terrificus venom

    Energy Technology Data Exchange (ETDEWEB)

    Marchi-Salvador, D. P.; Corrêa, L. C.; Salvador, G. H. M.; Magro, A. J. [Departamento de Física e Biofísica, Instituto de Biociências, UNESP, CP 510, 18618-000 Botucatu-SP (Brazil); Oliveira, C. Z. [Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, FCFRP, USP, Ribeirão Preto-SP (Brazil); Iulek, J. [Departamento de Química, UEPG, Ponta Grossa-PR (Brazil); Soares, A. M. [Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, FCFRP, USP, Ribeirão Preto-SP (Brazil); Fontes, M. R. M., E-mail: fontes@ibb.unesp.br [Departamento de Física e Biofísica, Instituto de Biociências, UNESP, CP 510, 18618-000 Botucatu-SP (Brazil)

    2007-12-01

    Crotoxin B is a basic phospholipase A{sub 2} found in the venom of C. durissus terrificus and is one of the subunits that constitute crotoxin. Here, the crystallization, X-ray diffraction data collection and molecular-replacement solution of a novel tetrameric complex formed by two dimers of crotoxin B isoforms are presented. Crotoxin B is a basic phospholipase A{sub 2} found in the venom of Crotalus durissus terrificus and is one of the subunits that constitute crotoxin. This heterodimeric toxin, which is the main component of C. d. terrificus venom, is completed by an acidic, nontoxic and non-enzymatic component (crotoxin A) and is involved in important envenomation effects, such as neurological disorders, myotoxicity and renal failure. Although crotoxin was first crystallized in 1938, no crystal structure is currently available for crotoxin, crotoxin A or crotoxin B. In this work, the crystallization, X-ray diffraction data collection to 2.28 Å resolution and molecular-replacement solution of a novel tetrameric complex formed by two dimers of crotoxin B isoforms (CB1 and CB2) is presented.

  10. Further evidence for pathogenicity of the TP53 tetramerization domain mutation p.Arg342Pro in Li-Fraumeni syndrome.

    Science.gov (United States)

    Etzold, Anna; Schröder, Julia C; Bartsch, Oliver; Zechner, Ulrich; Galetzka, Danuta

    2015-03-01

    Li-Fraumeni syndrome (LFS) is a rare genetic disease with a highly significant predisposition to multiple early-onset neoplasms. These neoplasms include adrenocortical carcinoma, sarcoma, leukemia and CNS tumors in children and sarcoma, breast cancer and lung cancer in adults. LFS is inherited in an autosomal dominant manner. In most patients germline mutations in the tumor suppressor gene TP53 are found. As the majority of known mutations affect the DNA-binding domain of the p53 protein, there are only a few case reports showing the clinical presentation of mutations outside of this mutational hotspot. Here we present a family with a typical LFS pedigree with patients suffering from early-onset lung cancer, bilateral breast cancer and osteosarcoma. TP53 sequence analysis of the index patient revealed the germline mutation c.1025G > C in a heterozygous state, resulting in an amino acid exchange from arginine to proline (p.Arg342Pro) in the tetramerization domain of p53. Using DNA from an old bedside blood typing test, the same mutation was found in the mother of the index patient, who had died of breast cancer 29 years ago. In conclusion, we provide evidence for the co-segregation of a TP53 tetramerization domain mutation and cancer phenotypes, but also report pre-symptomatic mutation carriers within the family. We review published recommendations for clinical management and surveillance of high-risk members in Li-Fraumeni kindreds.

  11. Evaluation of the potassium adsorption capacity of a potassium adsorption filter during rapid blood transfusion.

    Science.gov (United States)

    Matsuura, H; Akatsuka, Y; Muramatsu, C; Isogai, S; Sugiura, Y; Arakawa, S; Murayama, M; Kurahashi, M; Takasuga, H; Oshige, T; Yuba, T; Mizuta, S; Emi, N

    2015-05-01

    The concentration of extracellular potassium in red blood cell concentrates (RCCs) increases during storage, leading to risk of hyperkalemia. A potassium adsorption filter (PAF) can eliminate the potassium at normal blood transfusion. This study aimed to investigate the potassium adsorption capacity of a PAF during rapid blood transfusion. We tested several different potassium concentrations under a rapid transfusion condition using a pressure bag. The adsorption rates of the 70-mEq/l model were 76·8%. The PAF showed good potassium adsorption capacity, suggesting that this filter may provide a convenient method to prevent hyperkalemia during rapid blood transfusion. © 2015 International Society of Blood Transfusion.

  12. Development of novel nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric

    Science.gov (United States)

    Bondar, Yuliia; Kuzenko, Svetlana; Han, Do-Hung; Cho, Hyun-Kug

    2014-04-01

    A nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric was synthesized for selective removal of Cs ions from contaminated waters by a two-stage synthesis: radiation-induced graft polymerization of acrylic acid monomer onto the nonwoven polypropylene fabric surface with subsequent in situ formation of potassium nickel hexacyanoferrate (KNiHCF) nanoparticles within the grafted chains. Data of scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy confirmed the formation of KNiHCF homogeneous phase on the fabric surface, which consisted of crystalline cubic-shaped nanoparticles (70 to 100 nm). The efficiency of the synthesized adsorbent for removal of cesium ions was evaluated under various experimental conditions. It has demonstrated a rapid adsorption process, high adsorption capacity over a wide pH range, and selectivity in Cs ion removal from model solutions with high concentration of sodium ions.

  13. Shaker and Shal mediate transient calcium-independent potassium current in a Drosophila flight motoneuron.

    Science.gov (United States)

    Ryglewski, Stefanie; Duch, Carsten

    2009-12-01

    Ionic currents underlie the firing patterns, excitability, and synaptic integration of neurons. Despite complete sequence information in multiple species, our knowledge about ion channel function in central neurons remains incomplete. This study analyzes the potassium currents of an identified Drosophila flight motoneuron, MN5, in situ. MN5 exhibits four different potassium currents, two fast-activating transient ones and two sustained ones, one of each is calcium activated. Pharmacological and genetic manipulations unravel the specific contributions of Shaker and Shal to the calcium independent transient A-type potassium currents. alpha-dendrotoxin (Shaker specific) and phrixotoxin-2 (Shal specific) block different portions of the transient calcium independent A-type potassium current. Following targeted expression of a Shaker dominant negative transgene in MN5, the remaining A-type potassium current is alpha-dendrotoxin insensitive. In Shal RNAi knock down the remaining A-type potassium current is phrixotoxin-2 insensitive. Additionally, barium blocks calcium-activated potassium currents but also a large portion of phrixotoxin-2-sensitive A-type currents. Targeted knock down of Shaker or Shal channels each cause identical reduction in total potassium current amplitude as acute application of alpha-dendrotoxin or phrixotoxin-2, respectively. This shows that the knock downs do not cause upregulation of potassium channels underlying other A-type channels during development. Immunocytochemistry and targeted expression of modified GFP-tagged Shaker channels with intact targeting sequence in MN5 indicate predominant axonal localization. These data can now be used to investigate the roles of Shaker and Shal for motoneuron intrinsic properties, synaptic integration, and spiking output during behavior by targeted genetic manipulations.

  14. Does short-term potassium fertilization improve recovery from drought stress in laurel?

    Science.gov (United States)

    Oddo, Elisabetta; Inzerillo, Simone; Grisafi, Francesca; Sajeva, Maurizio; Salleo, Sebastiano; Nardini, Andrea

    2014-08-01

    Xylem hydraulic conductance varies in response to changes in sap solute content, and in particular of potassium (K(+)) ion concentration. This phenomenon, known as the 'ionic effect', is enhanced in embolized stems, where it can compensate for cavitation-induced loss of hydraulic conductance. Previous studies have shown that in well-watered laurel plants (Laurus nobilis L.), potassium concentration of the xylem sap and plant hydraulic conductance increased 24 h after fertilization with KCl. The aim of this work was to test whether water-stressed laurel plants, grown under low potassium availability, could recover earlier from stress when irrigated with a KCl solution instead of potassium-free water. Two-year-old potted laurel seedlings were subjected to water stress by suspending irrigation until leaf conductance to water vapour (g(L)) dropped to ∼30% of its initial value and leaf water potential (ψ(L)) reached the turgor loss point (ψ(TLP)). Plants were then irrigated either with water or with 25 mM KCl and monitored for water status, gas exchange and plant hydraulics recovery at 3, 6 and 24 h after irrigation. No significant differences were found between the two experimental groups in terms of ψ(L), g(L), plant transpiration, plant hydraulic conductance or leaf-specific shoot hydraulic conductivity. Analysis of xylem sap potassium concentration showed that there were no significant differences between treatments, and potassium levels were similar to those of potassium-starved but well-watered plants. In conclusion, potassium uptake from the soil solution and/or potassium release to the xylem appeared to be impaired in water-stressed plants, at least up to 24 h after relief from water stress, so that fertilization after the onset of stress did not result in any short-term advantage for recovery from drought. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Cooperative Noncovalent Interactions Induce Ion Pair Separation in Diphenylsilanides.

    Science.gov (United States)

    Marro, Eric A; Press, Eric M; Purkait, Tapas K; Jimenez, Daniel; Siegler, Maxime A; Klausen, Rebekka S

    2017-11-07

    This crystallographic and computational study describes an unusual potassium silanide structure. A contact ion pair is expected in the solid state between potassium and silicon, yet the potassium cation binds an aromatic ring and the anionic silanide interacts with CH bonds on neighboring crown ether molecules. These structure-bonding phenomena are attributed to strong soft-soft interactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Process for the conversion of sugars to lactic acid and 2-hydroxy-3-butenoic acid or esters thereof comprising a metallo-silicate material and a metal ion

    DEFF Research Database (Denmark)

    2015-01-01

    A process for the preparation of lactic acid and 2-hydroxy- 3-butenoic acid or esters thereof from a sugar in the presence of a metallo-silicate material, a metal ion and a solvent, wherein the metal ion is selected from one or more of the group consisting of potassium ions, sodium ions, lithium...... ions, rubidium ions and caesium ions....

  17. The Reaction between Iron(II) Iodide and Potassium Dichromate(VI) in Acidified Aqueous Solution

    Science.gov (United States)

    Talbot, Christopher

    2013-01-01

    This "Science note" teaching lesson explores the possible reaction between the ions in a reaction mixture consisting of iron(II) iodide and potassium dichromate(VI) in acidified aqueous solution. The electrode potentials will be used to deduce any spontaneous reactions under standard thermodynamic conditions (298 K, 1 bar (approximately…

  18. Impedance spectroscopy and surface study of potassium-selective silicone rubber membranes

    NARCIS (Netherlands)

    van der Wal, P.D.; van der Wal, Peter D.; Sudholter, Ernst; Sudhölter, Ernst J.R.; Boukamp, Bernard A.; Bouwmeester, Henricus J.M.; Reinhoudt, David

    1991-01-01

    Impedance spectroscopy measurements of silicone rubber membranes containing potassium-selective neutral carriers are reported. Two types of silicone rubbers are studied viz. the commercially available Siloprene and a novel copolymer, that was synthesized for application on Ion-Sensitive Field Effect

  19. Polymer Inclusion Membranes (PIM) for the Recovery of Potassium in the Presence of Competitive Cations

    NARCIS (Netherlands)

    Casadellà, Anna; Schaetzle, Olivier; Nijmeijer, Dorothea C.; Loos, Katja

    2016-01-01

    Potassium is an important nutrient used in fertilizers but is not always naturally available We investigated the properties of polymer inclusion membranes (PIM) regarding their selective recovery of K+ over competitive ions typically present in urine (Na+ and NH4+). The greatest flux was observed

  20. Bis(sulfonamide) transmembrane carriers allow pH-gated inversion of ion selectivity.

    Science.gov (United States)

    Roy, Arundhati; Biswas, Oindrila; Talukdar, Pinaki

    2017-03-09

    Bis(sulfonamide) based synthetic carriers are reported for inversion of ion selectivity upon deviation of pH within a narrow window. A liposomal membrane potential is also generated when potassium ions are passively transported by these carriers.

  1. Potassium

    Science.gov (United States)

    ... Don't Work Out Alone - Fitness Peer Support Breaking Down Barriers to Fitness Overcoming a Fitness Plateau Celebrating Your Fitness Success Step It Up - Tips to Pump Up Your Workout Walking Walking ...

  2. How are ion pumps and agrin signaling integrated?

    DEFF Research Database (Denmark)

    Tidow, Henning; Aperia, Anita; Nissen, Poul

    2010-01-01

    -potassium pump be connected and regulated? We envision an integrated model of ion pumping and signaling, considering in particular the recently discovered regulation of the sodium-potassium pump by agrin, a protein that is cleaved specifically by neurotrypsin at the synapse. Based on the recently solved...

  3. Kinetics of the valinomycin-induced potassium ion leak from liposomes with potassium thiocyanate enclosed

    NARCIS (Netherlands)

    Blok, M.C.; Gier, J. de; Deenen, L.L.M. van

    1974-01-01

    The kinetics of the valinomycin-induced K+ leak from egg lecithin liposomes with KCNS enclosed were studied by measuring the initial increase of the leak following the addition of the ionophore. Variation of liposome and valinomycin concentrations enabled a discrimination between the affinity of the

  4. Ion exchange phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  5. Detection of Mercury's Potassium Tail

    Science.gov (United States)

    Schmidt, Carl; Leblanc, Francois; Moore, Luke; Bida, Thomas A.

    2017-10-01

    Ground-based observations of Mercury's exosphere bridge the gap between the MESSENGER and BepiColombo missions and provide a broad counterpart to their in situ measurements. Here we report the first detection of Mercury's potassium tail in both emission lines of the D doublet. The sodium to potassium abundance ratio at 5 planetary radii down-tail is approximately 95, near the mid-point of a wide range of values that have been quoted over the planet's disk. This is several times the Na/K present in atmospheres of the Galilean satellites and more than an order of magnitude above Mercury's usual analogue, the Moon. The observations confirm that Mercury's anomalously high Na/K ratios cannot be explained by differences in neutral loss rates. The width and structure of the Na and K tails is comparable and both exhibit a persistent enhancement in their northern lobe. We interpret this as a signature of Mercury's offset magnetosphere; the exosphere's source rates are locally enhanced at the southern surface, and sloshing from radiation pressure and gravity guides this population into the northern region of the tail.

  6. Potassium loss with tissue potassium deficiency in rats during hypokinesia.

    Science.gov (United States)

    Tsiamis, Costas B; Kakuris, Kostas K; Deogenov, Viktor A; Yerullis, Kosmas B

    2008-04-01

    This study aims at showing the effect of hypokinesia (HK) on tissue potassium (K(+)) loss with different tissue K(+) depletion and tissue K(+) deficiency with different K(+) intake. To this end, tissue K(+) content, plasma K(+) level, and K(+) loss with and without K(+) supplements during HK were measured. Studies were conducted on male Wistar rats during a pre-experimental and an experimental period. Animals were equally divided into four groups: unsupplemented vivarium control rats (UVCR), unsupplemented hypokinetic rats (UHKR), supplemented vivarium control rats (SVCR), and supplemented hypokinetic rats (SHKR). SVCR and SHKR were supplemented daily with 2.50 mEq potassium chloride (KCl). Gastrocnemius muscle and right femur bone K(+) content reduced significantly, whereas plasma K(+) level and urine and fecal K(+) loss increased significantly in SHKR and UHKR compared with their pre-experimental values and the values in their respective vivarium controls (SVCR and UVCR). Bone and muscle K(+) content decreased more significantly, and plasma K(+) level and urine and fecal K(+) loss increased more significantly in SHKR than in UHKR. The greater tissue K(+) deficiency with higher than lower K(+) intake shows that the risk of higher tissue K(+) deficiency is directly related to K(+) intake. The higher K(+) loss with higher tissue K(+) deficiency and the lower K(+) loss with lower K(+) tissue deficiency shows that the risk of greater K(+) loss is directly related to tissue K(+) deficiency. Tissue K(+) deficiency increases more when the K(+) intake is higher and K(+) loss increases more with higher than lower tissue K(+) deficiency indicating that, during HK, tissue K(+) deficiency is due to the inability of the body to use K(+) but not to K(+) shortage in the diet.

  7. Reversible tetramerization of human TK1 to the high catalytic efficient form is induced by pyrophosphate, in addition to tripolyphosphates, or high enzyme concentration

    DEFF Research Database (Denmark)

    Munch-Petersen, Birgitte

    2009-01-01

    of ATP is necessary for tetramerisation and how the reaction velocity is influenced by the enzyme concentration. The results show that only two or three of the phosphate groups of ATP are necessary for tetramerisation, and that kinetics and tetramerisation are closely related. Furthermore, enzyme......Thymidine kinase (TK1) is a key enzyme in the salvage pathway of deoxyribonucleotide metabolism catalyzing the first step in the synthesis of dTTP by the transfer of a gamma-phosphate group from a nucleoside triphosphate to the 5´-hydroxyl group of thymidine forming dTMP. Human TK1 is cytosolic...... to regulation of TK1 expression at the transcriptional level. However, TK1 is also a regulatory enzyme that can interchange between its dimeric and tetrameric forms, which have low and high catalytic efficiencies, respectively, depending on pre-assay incubation with ATP.  Here, it is investigated which part...

  8. Long-pore Electrostatics in Inward-rectifier Potassium Channels

    Science.gov (United States)

    Robertson, Janice L.; Palmer, Lawrence G.; Roux, Benoît

    2008-01-01

    Inward-rectifier potassium (Kir) channels differ from the canonical K+ channel structure in that they possess a long extended pore (∼85 Å) for ion conduction that reaches deeply into the cytoplasm. This unique structural feature is presumably involved in regulating functional properties specific to Kir channels, such as conductance, rectification block, and ligand-dependent gating. To elucidate the underpinnings of these functional roles, we examine the electrostatics of an ion along this extended pore. Homology models are constructed based on the open-state model of KirBac1.1 for four mammalian Kir channels: Kir1.1/ROMK, Kir2.1/IRK, Kir3.1/GIRK, and Kir6.2/KATP. By solving the Poisson-Boltzmann equation, the electrostatic free energy of a K+ ion is determined along each pore, revealing that mammalian Kir channels provide a favorable environment for cations and suggesting the existence of high-density regions in the cytoplasmic domain and cavity. The contribution from the reaction field (the self-energy arising from the dielectric polarization induced by the ion's charge in the complex geometry of the pore) is unfavorable inside the long pore. However, this is well compensated by the electrostatic interaction with the static field arising from the protein charges and shielded by the dielectric surrounding. Decomposition of the static field provides a list of residues that display remarkable correspondence with existing mutagenesis data identifying amino acids that affect conduction and rectification. Many of these residues demonstrate interactions with the ion over long distances, up to 40 Å, suggesting that mutations potentially affect ion or blocker energetics over the entire pore. These results provide a foundation for understanding ion interactions in Kir channels and extend to the study of ion permeation, block, and gating in long, cation-specific pores. PMID:19001143

  9. Development of a Tetrameric Streptavidin Mutein with Reversible Biotin Binding Capability: Engineering a Mobile Loop as an Exit Door for Biotin

    Science.gov (United States)

    O'Sullivan, Valerie J.; Barrette-Ng, Isabelle; Hommema, Eric; Hermanson, Greg T.; Schofield, Mark; Wu, Sau-Ching; Honetschlaeger, Claudia; Ng, Kenneth K.-S.; Wong, Sui-Lam

    2012-01-01

    A novel form of tetrameric streptavidin has been engineered to have reversible biotin binding capability. In wild-type streptavidin, loop3–4 functions as a lid for the entry and exit of biotin. When biotin is bound, interactions between biotin and key residues in loop3–4 keep this lid in the closed state. In the engineered mutein, a second biotin exit door is created by changing the amino acid sequence of loop7–8. This door is mobile even in the presence of the bound biotin and can facilitate the release of biotin from the mutein. Since loop7–8 is involved in subunit interactions, alteration of this loop in the engineered mutein results in an 11° rotation between the two dimers in reference to wild-type streptavidin. The tetrameric state of the engineered mutein is stabilized by a H127C mutation, which leads to the formation of inter-subunit disulfide bonds. The biotin binding kinetic parameters (koff of 4.28×10−4 s−1 and Kd of 1.9×10−8 M) make this engineered mutein a superb affinity agent for the purification of biotinylated biomolecules. Affinity matrices can be regenerated using gentle procedures, and regenerated matrices can be reused at least ten times without any observable reduction in binding capacity. With the combination of both the engineered mutein and wild-type streptavidin, biotinylated biomolecules can easily be affinity purified to high purity and immobilized to desirable platforms without any leakage concerns. Other potential biotechnological applications, such as development of an automated high-throughput protein purification system, are feasible. PMID:22536357

  10. Radiolysis of Potassium Picrate in 77 K

    Science.gov (United States)

    Yakubik, D. G.; Pak, V. Kh; Anan'ev, V. A.; Ghyngazov, S. A.

    2016-02-01

    The formation of paramagnetic centers in potassium picrate under irradiation at low temperature was investigated. The heating irradiated at 77 K potassium picrate crystal to room temperature results in paramagnetic centers - 2,6-dinitro-para-quinone radicals, ortho- and para-iminoxyl radicals and atomic oxygen. These products are formed under irradiation at room temperature.

  11. Genetics Home Reference: potassium-aggravated myotonia

    Science.gov (United States)

    ... eating potassium-rich foods such as bananas and potatoes. Stiffness occurs in skeletal muscles throughout the body. Potassium-aggravated myotonia ranges in severity from mild episodes of muscle stiffness to severe, disabling disease with frequent attacks. Unlike some other forms of ...

  12. Potassium nutrition of heat-stressed lactating

    African Journals Online (AJOL)

    measure of dry bulb air temperature, wind velocity and solar radiation ... high milk potassium content (0,15-0,17%), (b) heat stress owing to increased ... level) as sub plots. All cows received different dietary potassium treatments in each 30-day period. Basal diet was 52% ground corn, 9,5% corn gluten meal, 1,0% urea,.

  13. Erythrocyte potassium and glutathione polymorphism determination ...

    African Journals Online (AJOL)

    This research is aimed at determining the erythrocyte potassium and glutathione polymorphisms and also to identify the relationship among the various blood parameters in Saanen x Malta crossbred goat raised in Turkey. The allele gene frequencies of KH and KL associated with the potassium concentration were ...

  14. Thanatochemistry: Study of synovial fluid potassium | Tumram ...

    African Journals Online (AJOL)

    The purpose of this paper is to test previously developed regression formulae for estimating death interval based on synovial fluid potassium and to assess its reliability in estimating death interval. Synovial fluid potassium was measured on a sample of 308 individuals. Death interval was regressed on synovial fluid ...

  15. Mechanism of electromechanical coupling in voltage-gated potassium channels

    Directory of Open Access Journals (Sweden)

    Rikard eBlunck

    2012-09-01

    Full Text Available Voltage-gated ion channels play a central role in the generation of action potentials in the nervous system. They are selective for one type of ion – sodium, calcium or potassium. Voltage-gated ion channels are composed of a central pore that allows ions to pass through the membrane and four peripheral voltage sensing domains that respond to changes in the membrane potential. Upon depolarization, voltage sensors in voltage-gated potassium channels (Kv undergo conformational changes driven by positive charges in the S4 segment and aided by pairwise electrostatic interactions with the surrounding voltage sensor. Structure-function relations of Kv channels have been investigated in detail, and the resulting models on the movement of the voltage sensors now converge to a consensus; the S4 segment undergoes a combined movement of rotation, tilt and vertical displacement in order to bring 3-4 e+ each through the electric field focused in this region. Nevertheless, the mechanism by which the voltage sensor movement leads to pore opening, the electromechanical coupling, is still not fully understood. Thus, recently, electromechanical coupling in different Kv channels has been investigated with a multitude of techniques including electrophysiology, 3D crystal structures, fluorescence spectroscopy and molecular dynamics simulations. Evidently, the S4-S5 linker, the covalent link between the voltage sensor and pore, plays a crucial role. The linker transfers the energy from the voltage sensor movement to the pore domain via an interaction with the S6 C-termini, which are pulled open during gating. In addition, other contact regions have been proposed. This review aims to provide (i an in-depth comparison of the molecular mechanisms of electromechanical coupling in different Kv channels; (ii insight as to how the voltage sensor and pore domain influence one another; and (iii theoretical predictions on the movement of the cytosolic face of the KV channels

  16. A possible low intracellular potassium in obesity.

    Science.gov (United States)

    Colt, E W; Wang, J; Stallone, F; Van Itallie, T B; Pierson, R N

    1981-03-01

    In comparison with lean marathon runners whose fat content was 15%, obese subjects with a fat content of 55% showed a 36% reduction in intracellular potassium. It is hypothesized that as much as 60% of this decrease may have been due to the lower proportion of muscle (which has the highest intracellular potassium of any tissue) in the fat free mass of very obese subjects. The remainder of the decrease seems to have been a measurement artefact owing to self-absorption of gamma rays by adipose tissue, most of which is distributed over potassium rich lean tissue. The low intracellular potassium values found in obesity should not be interpreted as necessarily signifying potassium deficiency.

  17. [Thermodynamic approach to the selection of polyuronide sequestrants for protection of the human body from toxic metal ions. Interactions of polyuronides with lead ions].

    Science.gov (United States)

    Braudo, E E; Danilova, I V; Dianova, V T; Kobak, V V; Plashchina, I G

    2001-01-01

    Binding isotherms of Pb2+ ions with potassium pectate and potassium alginate with relatively low content of blocks of L-guluronic residues (20%) have been determined. Interactions of Pb2+ ions with polyuronides studied is cooperative. Maximum values of binding constants are an order of magnitude higher than previously determined ones for Ca2+ and Sr2+ ions. Along with ion-coordination ("stoichiometric") interactions, alginate is typified by so-called extra-stoichiometric binding of Pb2+ ions, which presumably proceeds by a coprecipitation mechanism. Limitations of the thermodynamic approach to the selection of sequestrants for human body protection from toxic metal ions are discussed.

  18. Use of voltage clamp fluorimetry in understanding potassium channel gating: a review of Shaker fluorescence data.

    Science.gov (United States)

    Horne, A J; Fedida, D

    2009-06-01

    Voltage clamp fluorimetry (VCF) utilizes fluorescent probes that covalently bind to cysteine residues introduced into proteins and emit light as a function of their environment. Measurement of this emitted light during membrane depolarization reveals changes in the emission level as the environment of the labelled residue changes. This allows for the correlation of channel gating events with movement of specific protein moieties, at nanosecond time resolution. Since the pioneering use of this technique to investigate Shaker potassium channel activation movements, VCF has become an invaluable technique used to understand ion channel gating. This review summarizes the theory and some of the data on the application of the VCF technique. Although its usage has expanded beyond voltage-gated potassium channels and VCF is now used in a number of other voltage- and ligand-gated channels, we will focus on studies conducted in Shaker potassium channels, and what they have told us about channel activation and inactivation gating.

  19. Effects of low energy helium plasma irradiation on potassium doped tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Xiaoyan [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Key Subject Laboratory of National Defense for Radioactive Waste and Environmental Security, Southwest University of Science and Technology, Mianyang (China); Huang, Bo [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Liu, Dongping; Fan, Hongyu [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Liu, Ning [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Tang, Jun, E-mail: tangjun@scu.edu.cn [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China)

    2017-04-15

    Effects of helium plasma irradiation on spark plasma sintering (SPS) W-K, pure W and traditionally sintered commercial W-K have been studied, concerning the density, grain size and potassium content as the influence factors. Pinholes are formed under 120 eV He ions at 600 °C and 1 × 10{sup 23} m{sup −2} fluence on the surface of all samples. It is found that SPS-sintered W-K shows the best irradiation resistance among the present samples, and SPS-sintered pure W exhibits higher irradiation tolerance than commercial W-K. Different He-plasma tolerance was observed among the SPS-sintered W-K samples due to varied potassium content and grain size. In addition, the microstructure evolution under helium irradiation, the growth-migration of helium bubbles and their interactions of potassium bubbles have also been discussed.

  20. Cole–Cole Parameter Characterization of Urea and Potassium for Improving Dialysis Treatment Assessment

    DEFF Research Database (Denmark)

    Jensen, Peter Damsgaard; Meaney, Paul M.; Epstien, Neil R.

    2012-01-01

    In this letter, we investigate the characteristics of the dielectric properties of urea and ions such as potassium and sodium, which are the principal molecules studied during dialysis treatment. The method involves measuring the electrical properties of varying concentrations of the constituent...... solutions over a broad frequency range and estimating the associated Cole–Cole parameters. We utilized concentrations above those expected in vivo to achieve a more accurate characterization. In these studies, we found that the conductivity was essentially constant with respect to urea concentration but had...... a strong, nearly linear correlation with potassium. In addition, the alpha factor had a distinct, monotonically varying relationship for both urea and potassium with significantly different initial slopes. Utilizing these two curves, simple inversion algorithms are possible to compute the solute...

  1. Serum potassium concentrations: Importance of normokalaemia.

    Science.gov (United States)

    Heras, Manuel; Fernández-Reyes, María José

    2017-06-21

    Abnormalities in potassium concentrations are associated with morbidity and mortality. In recent years it has been considered that small variations in serum potassium concentrations within normal intervals may also be associated with mortality. Strategies for achieving normokalaemia include dietary measures, limiting the use of potassium retaining drugs, and use of conventional cation exchange resins (calcium/sodium polystyrene sulfonate) and/or the new non-absorbed cation exchange polymer (patiromer). Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  2. Role of the activation gate in determining the extracellular potassium dependency of block of HERG by trapped drugs.

    Science.gov (United States)

    Pareja, Kristeen; Chu, Elaine; Dodyk, Katrina; Richter, Kristofer; Miller, Alan

    2013-01-01

    Drug induced long QT syndrome (diLQTS) results primarily from block of the cardiac potassium channel HERG (human-ether-a-go-go related gene). In some cases long QT syndrome can result in the lethal arrhythmia torsade de pointes, an arrhythmia characterized by a rapid heart rate and severely compromised cardiac output. Many patients requiring medication present with serum potassium abnormalities due to a variety of conditions including gastrointestinal dysfunction, renal and endocrine disorders, diuretic use, and aging. Extracellular potassium influences HERG channel inactivation and can alter block of HERG by some drugs. However, block of HERG by a number of drugs is not sensitive to extracellular potassium. In this study, we show that block of WT HERG by bepridil and terfenadine, two drugs previously shown to be trapped inside the HERG channel after the channel closes, is insensitive to extracellular potassium over the range of 0 mM to 20 mM. We also show that bepridil block of the HERG mutant D540K, a mutant channel that is unable to trap drugs, is dependent on extracellular potassium, correlates with the permeant ion, and is independent of HERG inactivation. These results suggest that the lack of extracellular potassium dependency of block of HERG by some drugs may in part be related to the ability of these drugs to be trapped inside the channel after the channel closes.

  3. Qualitative Carbohydrate Analysis using Alkaline Potassium ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 3. Qualitative Carbohydrate Analysis using Alkaline Potassium Ferricyanide. Sangeeta Pandita Saral Baweja. Classroom Volume 21 Issue 3 March 2016 pp 285-288 ...

  4. Osmotic stress responses and plant growth controlled by potassium transporters in Arabidopsis.

    Science.gov (United States)

    Osakabe, Yuriko; Arinaga, Naoko; Umezawa, Taishi; Katsura, Shogo; Nagamachi, Keita; Tanaka, Hidenori; Ohiraki, Haruka; Yamada, Kohji; Seo, So-Uk; Abo, Mitsuru; Yoshimura, Etsuro; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2013-02-01

    Osmotic adjustment plays a fundamental role in water stress responses and growth in plants; however, the molecular mechanisms governing this process are not fully understood. Here, we demonstrated that the KUP potassium transporter family plays important roles in this process, under the control of abscisic acid (ABA) and auxin. We generated Arabidopsis thaliana multiple mutants for K(+) uptake transporter 6 (KUP6), KUP8, KUP2/SHORT HYPOCOTYL3, and an ABA-responsive potassium efflux channel, guard cell outward rectifying K(+) channel (GORK). The triple mutants, kup268 and kup68 gork, exhibited enhanced cell expansion, suggesting that these KUPs negatively regulate turgor-dependent growth. Potassium uptake experiments using (86)radioactive rubidium ion ((86)Rb(+)) in the mutants indicated that these KUPs might be involved in potassium efflux in Arabidopsis roots. The mutants showed increased auxin responses and decreased sensitivity to an auxin inhibitor (1-N-naphthylphthalamic acid) and ABA in lateral root growth. During water deficit stress, kup68 gork impaired ABA-mediated stomatal closing, and kup268 and kup68 gork decreased survival of drought stress. The protein kinase SNF1-related protein kinases 2E (SRK2E), a key component of ABA signaling, interacted with and phosphorylated KUP6, suggesting that KUP functions are regulated directly via an ABA signaling complex. We propose that the KUP6 subfamily transporters act as key factors in osmotic adjustment by balancing potassium homeostasis in cell growth and drought stress responses.

  5. Connexin 43 impacts on mitochondrial potassium uptake

    Directory of Open Access Journals (Sweden)

    Kerstin eBoengler

    2013-06-01

    Full Text Available In cardiomyocytes, connexin 43 (Cx43 forms gap junctions and unopposed hemichannels at the plasma membrane, but the protein is also present at the inner membrane of subsarcolemmal mitochondria. Both inhibition and genetic ablation of Cx43 reduce ADP-stimulated complex 1 respiration. Since mitochondrial potassium influx impacts on oxygen consumption, we investigated whether or not inhibition or ablation of mitochondrial Cx43 alters mitochondrial potassium uptake.Subsarcolemmal mitochondria were isolated from rat left ventricular (LV myocardium and loaded with the potassium-sensitive dye PBFI. Intramitochondrial potassium was replaced by TEA (tetraethylammonium. Mitochondria were incubated under control conditions or treated with 250 µM Gap19, a peptide that specifically inhibits Cx43-dependent hemichannels at plasma membranes. Subsequently, 140 mM KCl was added and the slope of the increase in PBFI fluorescence over time was calculated. The slope of the PBFI fluorescence of the control mitochondria was set to 100%. In the presence of Gap19, the mitochondrial potassium influx was reduced from 100±11.6 % in control mitochondria to 65.5±10.7 % (n=6, p<0.05. In addition to the pharmacological inhibition of Cx43, potassium influx was studied in mitochondria isolated from conditional Cx43 knockout mice. Here, the ablation of Cx43 was achieved by the injection of 4-hydroxytamoxifen (Cx43Cre-ER(T/fl + 4-OHT. The mitochondria of the Cx43Cre-ER(T/fl + 4-OHT mice contained 3±1% Cx43 (n=6 of that in control mitochondria (100±11%, n=8, p<0.05. The ablation of Cx43 (n=5 reduced the velocity of the potassium influx from 100±11.2 % in control mitochondria (n=9 to 66.6±5.5 % (p<0.05.Taken together, our data indicate that both pharmacological inhibition and genetic ablation of Cx43 reduce mitochondrial potassium influx.

  6. The Ketogenic Diet and Potassium Channel Function

    Science.gov (United States)

    2015-11-01

    1 AWARD NUMBER: W81XWH-13-1-0463 TITLE: The Ketogenic Diet and Potassium Channel Function PRINCIPAL INVESTIGATOR: Dr. Geoffrey Murphy...NUMBER The Ketogenic Diet and Potassium Channel Function 5b. GRANT NUMBER W81XWH-13-1-0463 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Geoffrey Murphy...The overall objective of this Discovery Award was to explore the hypothesis the ketogenic diet (KD) regulates neuronal excitability by influencing

  7. 21 CFR 181.34 - Sodium nitrite and potassium nitrite.

    Science.gov (United States)

    2010-04-01

    ... fixatives and preservative agents, with or without sodium or potassium nitrate, in the curing of red meat... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite and potassium nitrite. 181.34...-Sanctioned Food Ingredients § 181.34 Sodium nitrite and potassium nitrite. Sodium nitrite and potassium...

  8. Potassium chloride production by microcline chlorination

    Energy Technology Data Exchange (ETDEWEB)

    Orosco, Pablo, E-mail: porosco@unsl.edu.ar [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, San Luis (Argentina); Ruiz, María del Carmen [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina)

    2015-08-10

    Highlights: • Use of chlorination for the KCl production. • The reagents used were microcline, hydromagnesite and chlorine. • Isothermal and non-isothermal assays were performed in Cl{sub 2}–N{sub 2} mixture. • The chlorination generated KCl at 700 °C. • The chlorination products promote KCl formation. - Abstract: The potassium chloride is one of the most important fertilizers used in agriculture. The current demand of this salt makes interesting the study of potassium chloride production from unconventional potassium resources. In this work the potassium chloride production by chlorination of microcline was investigated. The starting reagents were microcline, hydromagnesite and chlorine. Non-isothermal and isothermal chlorination assays were carried out in a thermogravimetric device adapted to work in corrosive atmospheres. The temperature effect on potassium extraction and the phase transformations produced during chlorination of microcline were studied. The reagents and reaction products were analyzed by X-ray fluorescence (XRF) and X-ray diffraction (XRD). The experimental results indicated that by chlorination of microcline an important extraction of potassium in the temperature range from 800 to 900 °C was produced. Moreover, at 800 °C the forsterite, enstatite and magnesium aluminate spinel phases were generated.

  9. Novel polymeric potassium complex: Its synthesis, structural characterization, photoluminescence and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ceyhan, Goekhan [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Tuemer, Mehmet, E-mail: mtumer@ksu.edu.tr [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Koese, Muhammet; McKee, Vickie [Chemistry Department, Loughborough University, LE11 3TU Leicestershire (United Kingdom)

    2012-03-15

    In this paper, we obtained a novel poly(vanillinato potassium) complex (PVP) as a single crystal and characterized by analytical and spectroscopic methods. A single crystal of the PVP was obtained from the acetone solution. X-ray structural data show that crystals contain polymeric K{sup +} complex of vanillin. Each potassium ion in the polymeric structure is identical and seven-coordinate, bonded to two methoxy, two phenoxy and three aldehyde oxygen atoms from four vaniline molecules. Two aldehyde oxygen atoms are bridging between potassium ions. It crystallizes in the monoclinic system, space group P2{sub 1}/c, with lattice parameters a=9.6215(10) A, b=17.4139(19) A, c=9.6119(10) A, {beta}=100.457(2) Degree-Sign and Z=4. Thermal properties of the PVP were investigated by TGA, DTA and DSC methods. The electrochemical properties of the complex were studied in different solvents and at various scan rates. The luminescence properties of the complex in different solvents and at different pH values have been investigated. The results show that the complex exhibits more efficient luminescence property in CH{sub 3}CN and n-butanol. - Highlights: Black-Right-Pointing-Pointer Novel polymeric potassium complex was prepared and fully characterized. Black-Right-Pointing-Pointer X-ray crystal structure of complex was reported. Black-Right-Pointing-Pointer Electrochemical properties of compound were investigated. Black-Right-Pointing-Pointer Thermal and DSC measurements of complex were examined.

  10. Metrological assessment of TDR performance for measurement of potassium concentration in soil solution

    Directory of Open Access Journals (Sweden)

    Isaac de M. Ponciano

    2016-04-01

    Full Text Available ABSTRACT Despite the growing use of the time domain reflectometry (TDR technique to monitoring ions in the soil solution, there are few studies that provide insight into measurement error. To overcome this lack of information, a methodology, based on the central limit theorem error, was used to quantify the uncertainty associated with using the technique to estimate potassium ion concentration in two soil types. Mathematical models based on electrical conductivity and soil moisture derived from TDR readings were used to estimate potassium concentration, and the results were compared to potassium concentration determined by flame spectrophotometry. It was possible to correct for random and systematic errors associated with TDR readings, significantly increasing the accuracy of the potassium estimation methodology. However, a single TDR reading can lead to an error of up to ± 18.84 mg L-1 K+ in soil solution (0 to 3 dS m-1, with a 95.42% degree of confidence, for a loamy sand soil; and an error of up to ± 12.50 mg L-1 of K+ (0 to 2.5 dS m-1 in soil solution, with a 95.06% degree of confidence, for a sandy clay soil.

  11. Thermodynamic properties of potassium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Byker, H.J. (Montana State Univ., Bozeman); Eliezer, I.; Howald, R.C.; Ehlert, T.C.

    1979-09-01

    KO/sub 0/ /sub 5/ has been prepared by the reaction of excess potassium with KNO/sub 3/ in an effusion cell. Observations of the 2KO/sub 0/ /sub 5/ ..-->.. K/sub 2/O(g) equilibrium mass spectrometrically give a new value for the enthalpy of solid KO/sub 0/ /sub 5/, ..delta..H/sub f,298//sup 0/ = -170 +- 5 kJ mol/sup -1/. Observations on KO/sup +/ in the same series of experiments give good estimates for the thermodynamic properties of K/sub 2/O/sub 2/(g). This leads to an improved interpretation of data on the vaporization of KO/sub 0/ /sub 5/-K/sub 2/O/sub 2/ mixtures and solutions. Similarly literature data on the K/sub 2/O/sub 2/-KO/sub 2/ system have been collected and reexamined, leading to the values ..delta..H/sub f,298//sup 0/ = -495.4 kJ mol/sup -1/ and S/sub 298//sup 0/ = 110.1 J mol/sup -1/ K/sup -1/ for K/sub 2/O/sub 2/(s). We have calculated a preliminary phase diagram for the entire region from KO/sub 0/ /sub 5/ to KO/sub 2/, treating the liquid as solutions of O (1) in KO/sub 0/ /sub 5/ (1). Differential thermal analysis data supporting the calculated phase diagram are reported.

  12. Poly[μ-(1,3-dihydroxypropan-2-olato-potassium

    Directory of Open Access Journals (Sweden)

    Gabriele Schatte

    2011-02-01

    Full Text Available The asymmetric unit of the title compound, [K(C3H7O3]n or K[H2gl]n, common name potassium glycerolate, contains half the K+ cation and half of the glycerolate anion. The other half of the anion is generated through a mirror plane passing through the K atom, and a C, an H and an O atom of the glycerolate ligand. The K+ ion is coordinated by the O atoms of the OH groups, leading to a six-membered chelate ring that adopts a very distorted boat conformation. The negatively charged O atom of the glycerolate anion, [H2gl−], is found in the flagpole position and forms an ionic bond with the K+ ion. The O atoms of the hydroxo groups are coordinated to two K+ ions, whereas the negatively charged O atom is bonded to one K+ ion. The K+ ion is coordinated by three other symmetry-related monodentate H2gl− ligands, so that each H2gl− ligand is bonded to two K+ ions, and the potassium has a seven-coordinate environment. The H2gl− ligands are connected via a strong O—H...O hydrogen bond and, together with the K...O interconnections, form polymeric sheets which propagate in the directions of the a and b axes.

  13. Venezuelan equine Encephalitis virus capsid protein forms a tetrameric complex with CRM1 and importin alpha/beta that obstructs nuclear pore complex function.

    Science.gov (United States)

    Atasheva, Svetlana; Fish, Alexander; Fornerod, Maarten; Frolova, Elena I

    2010-05-01

    Development of the cellular antiviral response requires nuclear translocation of multiple transcription factors and activation of a wide variety of cellular genes. To counteract the antiviral response, several viruses have developed an efficient means of inhibiting nucleocytoplasmic traffic. In this study, we demonstrate that the pathogenic strain of Venezuelan equine encephalitis virus (VEEV) has developed a unique mechanism of nuclear import inhibition. Its capsid protein forms a tetrameric complex with the nuclear export receptor CRM1 and the nuclear import receptor importin alpha/beta. This unusual complex accumulates in the center channel of the nuclear pores and blocks nuclear import mediated by different karyopherins. The inhibitory function of VEEV capsid protein is determined by a short 39-amino-acid-long peptide that contains both nuclear import and supraphysiological nuclear export signals. Mutations in these signals or in the linker peptide attenuate or completely abolish capsid-specific inhibition of nuclear traffic. The less pathogenic VEEV strains contain a wide variety of mutations in this peptide that affect its inhibitory function in nuclear import. Thus, these mutations appear to be the determinants of this attenuated phenotype. This novel mechanism of inhibiting nuclear transport also shows that the nuclear pore complex is vulnerable to unusual cargo receptor complexes and sheds light on the importance of finely adjusted karyopherin-nucleoporin interactions for efficient cargo translocation.

  14. Crystallization and preliminary crystallographic analysis of the tetrameric form of phosphofructokinase-2 from Escherichia coli, a member of the ribokinase family

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera, Ricardo; Caniuguir, Andrés [Laboratorio de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago (Chile); Ambrosio, Andre L. B. [Centro de Biotecnologia Molecular Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador Sãocarlense 400, CEP 13560-970, São Carlos, SP (Brazil); Guixé, Victoria [Laboratorio de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago (Chile); Garratt, Richard C. [Centro de Biotecnologia Molecular Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador Sãocarlense 400, CEP 13560-970, São Carlos, SP (Brazil); Babul, Jorge, E-mail: jbabul@uchile.cl [Laboratorio de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago (Chile)

    2006-09-01

    The phosphofructokinase-2 enzyme from E. coli was crystallized in its tetrameric inhibited form. This is the only member of the ribokinase family known to suffer a transition from dimer to tetramer in response to the allosteric binding of MgATP. Escherichia coli contains two phosphofructokinases, Pfk-1 and Pfk-2, which belong to unrelated protein families. In addition to catalytic function, the enzymes have converged in showing substrate inhibition by the nucleotide MgATP. However, although both Pfk-1 and Pfk-2 have been extensively characterized biochemically, only the structure of the former has been solved by X-ray diffraction. In order to fully understand how the same function has evolved on different structural folds, Pfk-2 has been crystallized by the hanging-drop vapour-diffusion method using PEG 6000 as precipitant. Single crystals were grown in the presence of MgATP and diffracted to 1.98 Å. The crystals belong to the orthorhombic system, space group P222{sub 1}, with unit-cell parameters a = 42.8, b = 86.8, c = 171.3 Å. The calculated Matthews coefficient of 2.45 Å{sup 3} Da{sup −1} indicates the presence of two monomers in the asymmetric unit, corresponding to a solvent content of 49%. Structure determination is ongoing.

  15. Tetrameric far-red fluorescent protein as a scaffold to assemble an octavalent peptide nanoprobe for enhanced tumor targeting and intracellular uptake in vivo.

    Science.gov (United States)

    Luo, Haiming; Yang, Jie; Jin, Honglin; Huang, Chuan; Fu, Jianwei; Yang, Fei; Gong, Hui; Zeng, Shaoqun; Luo, Qingming; Zhang, Zhihong

    2011-06-01

    Relatively weak tumor affinities and short retention time in vivo hinder the application of targeting peptides in tumor molecular imaging. Multivalent strategies based on various scaffolds have been utilized to improve the ability of peptide-receptor binding or extend the clearance time of peptide-based probes. Here, we use a tetrameric far-red fluorescent protein (tfRFP) as a scaffold to create a self-assembled octavalent peptide fluorescent nanoprobe (Octa-FNP) using a genetic engineering approach. The multiligand connecting, fluorophore labeling and nanostructure formation of Octa-FNP were performed in one step. In vitro studies showed Octa-FNP is a 10-nm fluorescent probe with excellent serum stability. Cellular uptake of Octa-FNP by human nasopharyngeal cancer 5-8F cells is 15-fold of tetravalent probe, ∼80-fold of monovalent probe and ∼600-fold of nulvalent tfRFP. In vivo enhanced tumor targeting and intracellular uptake of Octa-FNP were confirmed using optical imaging and Western blot analysis. It achieved extremely high contrast of Octa-FNP signal between tumor tissue and normal organs, especially seldom Octa-FNP detected in liver and spleen. Owing to easy preparation, precise structural and functional control, and multivalent effect, Octa-FNP provides a powerful tool for tumor optical molecular imaging and evaluating the targeting ability of numerous peptides in vivo.

  16. Alterations in sodium-potassium regulation in mononuclear leucocytes from young borderline hypertensive and offspring of hypertensive patients

    DEFF Research Database (Denmark)

    Nielsen, J R; Pedersen, K E; Klitgaard, N A

    1988-01-01

    Membrane ion transports were investigated in lymphocytes from young normotensive and borderline hypertensive offspring with and without heredity for hypertension. Borderline hypertension per se was associated with an enhancement of sodium-potassium pump activity. Heredity per se was associated...... with increased sodium influx and ouabain-resistant sodium efflux....

  17. Self-focusing in chromium-doped potassium niobate single ceramic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Castillo T, J.; Gonzalez M, S.; Aguirre L, A.; Hernandez, M.B.; Aguilar M, J.A. [Instituto de Fisica y Matematicas, Universidad Tecnologica de la Mixteca, 69000, Huajuapan de Leon, Oaxaca (Mexico); Hernandez A, J. [lFUNAM, PO Box 20-364, 01000 Mexico, DF (Mexico)]. e-mail: jaimec@mixteco.utm.mx

    2006-07-01

    The self-focusing and nonlinear optical absorption in a chromium-doped potassium niobate single ceramic crystal have been investigated. The third-order electric susceptibility X{sup (3)} at continuous 532 nm radiation is estimated based on a band transport model describing photo refractive properties for this electro-optic material. An anisotropic behavior on its nonlinear optical absorption properties has also been observed due to the presence of chromium ions. (Author)

  18. A role for two-pore potassium (K2P) channels in endometrial epithelial function.

    OpenAIRE

    Patel, SK; Jackson, L.; Warren, AY; P. Arya; Shaw, RW; Khan, RN

    2013-01-01

    The human endometrial epithelium is pivotal to menstrual cycle progression, implantation and early pregnancy. Endometrial function is directly regulated by local factors that include pH, oxygen tension and ion concentrations to generate an environment conducive to fertilization. A superfamily of potassium channels characterized by two-pore domains (K2P) and encoded by KCNK genes is implicated in the control of the cell resting membrane potential through the generation of leak currents and mod...

  19. PIST (GOPC) modulates the oncogenic voltage-gated potassium channel KV10.1

    OpenAIRE

    Herrmann, Solveig; Ninkovic, Milena; Kohl, Tobias; Pardo, Luis A.

    2013-01-01

    Although crucial for their correct function, the mechanisms controlling surface expression of ion channels are poorly understood. In the case of the voltage-gated potassium channel KV10.1, this is determinant not only for its physiological function in brain, but also for its pathophysiology in tumors and possible use as a therapeutic target. The Golgi resident protein PIST binds several membrane proteins, thereby modulating their expression. Here we describe a PDZ domain-mediated interaction ...

  20. PIST (GOPC) modulates the oncogenic voltage-gated potassium channel KV10.1

    OpenAIRE

    Solveig eHerrmann; Milena eNinkovic; Tobias eKohl; Pardo, Luis A.

    2013-01-01

    Although crucial for their correct function, the mechanisms controlling surface expression of ion channels are poorly understood. In the case of the voltage-gated potassium channel KV10.1,this is determinant not only for its physiological function in brain, but also for its pathophysiology in tumors and possible use as a therapeutic target. The Golgi resident protein PIST binds several membrane proteins, thereby modulating their expression. Here we describe a PDZ domain-mediated interaction o...

  1. Precise determination of the isotopic composition of potassium: Application to terrestrial rocks and lunar soils

    Science.gov (United States)

    Humayun, Munir; Clayton, Robert N.

    1995-05-01

    We detail a method for the precise and accurate determination of isotopic variations in the 41K/39K ratio with a precision of ±0.5‰ (2 σm). Purified potassium is chemically extracted from rocks, soils, minerals, or solutions by ion exchange chromatography. Complete chemical yields (>99.8%) are achieved in order to avoid laboratory-induced isotopic fractionations. The purified potassium is converted to a glass by melting with barium borate flux, and the resultant bead is mounted for ion probe analysis. The SIMS method utilized by the ion probe produces extremely stable K+ ion beams, with no measurable temporal variability in the isotope ratio. The instrumental fractionation is steady at about -4‰, and is corrected for by measurement of a standard. The measurement of gravimetrically prepared isotopic standards indicates that the method is accurate at the stated level of precision and free of egregious errors. Analysis of terrestrial samples including peridotite, basalts, granites, carbonatite, biotite schists, and seawater, indicate the complete absence of isotopic variations in δ41 1K among terrestrial materials at the 0.5%o level. Application to lunar soils and a regolith breccia confirms previously observed large isotopic fractionation effects (Garner et al., 1975a; Church et al., 1976). Some lunar soils, e.g., 14163, are shown to have large sample heterogeneity (≈7%o), while others, e.g., soils and a regolith breccia at several Apollo 15 sites (Station 7/9), are homogeneous at the level of analytical precision. The presence of potassium isotopic effects in bulk soils (up to +12.7‰ in this study) with magnitudes comparable to the Rayleigh fractionation factor (25‰) indicates that volatility during micrometeorite impact melting played a large role in lunar regolith formation. As much as 15% of the regolith potassium has been lost from the Moon, through the tenuous lunar atmosphere.

  2. Extracellular potassium inhibits Kv7.1 potassium channels by stabilizing an inactivated state

    DEFF Research Database (Denmark)

    Larsen, Anders Peter; Steffensen, Annette Buur; Grunnet, Morten

    2011-01-01

    Kv7.1 (KCNQ1) channels are regulators of several physiological processes including vasodilatation, repolarization of cardiomyocytes, and control of secretory processes. A number of Kv7.1 pore mutants are sensitive to extracellular potassium. We hypothesized that extracellular potassium also...

  3. Effects of 15 Hz square wave magnetic fields on the voltage-gated sodium and potassium channels in prefrontal cortex pyramidal neurons.

    Science.gov (United States)

    Zheng, Yu; Dou, Jun-Rong; Gao, Yang; Dong, Lei; Li, Gang

    2017-04-01

    Although magnetic fields have significant effects on neurons, little is known about the mechanisms behind their effects. The present study aimed to measure the effects of magnetic fields on ion channels in cortical pyramidal neurons. Cortical pyramidal neurons of Kunming mice were isolated and then subjected to 15 Hz, 1 mT square wave (duty ratio 50%) magnetic fields stimulation. Sodium currents (INa), transient potassium currents (IA) and delayed rectifier potassium currents (IK) were recorded by whole-cell patch clamp method. We found that magnetic field exposure depressed channel current densities, and altered the activation kinetics of sodium and potassium channels. The inactivation properties of INa and IA were also altered. Magnetic field exposure alters ion channel function in neurons. It is likely that the structures of sodium and potassium channels were influenced by the applied field. Sialic acid, which is an important component of the channels, could be the molecule responsible for the reported results.

  4. Electrochemical characterizations on MnO2 supercapacitors with potassium polyacrylate and potassium polyacrylate-co-polyacrylamide gel polymer electrolytes

    KAUST Repository

    Lee, Kuang-Tsin

    2009-11-01

    MnO2·nH2O supercapacitors with potassium polyacrylate (PAAK) and potassium polyacrylate-co-polyacrylamide (PAAK-co-PAAM) gel polymer electrolytes (GPEs) having the weight compositions of polymer:KCl:H2O = 9%:6.7%:84.3% have been characterized for their electrochemical performance. Compared with the liquid electrolyte (LE) counterpart, the GPE cells exhibit remarkable (∼50-130%) enhancement in specific capacitance of the oxide electrode, and the extent of the enhancement increases with increasing amount of the carboxylate groups in the polymers as well as with increasing oxide/electrolyte interfacial area. In situ X-ray absorption near-edge structure (XANES) analysis indicates that the oxide electrodes of the GPE cells possess higher Mn-ion valences and are subjected to greater extent of valence variation than that of the LE cell upon charging/discharging over the same potential range. Copolymerization of PAAK with PAAM greatly improves the cycling stability of the MnO2·nH2O electrode, and the improvement is attributable to the alkaline nature of the amino groups. Both GPEs exhibit ionic conductivities greater than 1.0 × 10-1 S cm-1 and are promising for high-rate applications. © 2009 Elsevier Ltd. All rights reserved.

  5. Graphene oxide and DNA aptamer based sub-nanomolar potassium detecting optical nanosensor

    Science.gov (United States)

    Datta, Debopam; Sarkar, Ketaki; Mukherjee, Souvik; Meshik, Xenia; Stroscio, Michael A.; Dutta, Mitra

    2017-08-01

    Quantum-dot (QD) based nanosensors are frequently used by researchers to detect small molecules, ions and different biomolecules. In this article, we present a sensor complex/system comprised of deoxyribonucleic acid (DNA) aptamer, gold nanoparticle and semiconductor QD, attached to a graphene oxide (GO) flake for detection of potassium. As reported herein, it is demonstrated that QD-aptamer-quencher nanosensor functions even when tethered to GO, opening the way to future applications where sensing can be accomplished simultaneously with other previously demonstrated applications of GO such as serving as a nanocarrier for drug delivery. Herein, it is demonstrated that the DNA based thrombin binding aptamer used in this study undergoes the conformational change needed for sensing even when the nanosensor complex is anchored to the GO. Analysis with the Hill equation indicates the interaction between aptamer and potassium follows sigmoidal Hill kinetics. It is found that the quenching efficiency of the optical sensor is linear with the logarithm of concentration from 1 pM to 100 nM and decreases for higher concentration due to unavailability of aptamer binding sites. Such a simple and sensitive optical aptasensor with minimum detection capability of 1.96 pM for potassium ion can also be employed in-vitro detection of different physiological ions, pathogens and disease detection methods.

  6. Effects of top excision on the potassium accumulation and expression of potassium channel genes in tobacco.

    Science.gov (United States)

    Dai, Xiao Yan; Su, Yi Rong; Wei, Wen Xue; Wu, Jin Shui; Fan, Ye Kuan

    2009-01-01

    The effects of the removal of the shoot apex of tobacco on the relative transcript levels of potassium channel genes, determined by real-time PCR, and on the relationship between the expression of genes encoding potassium channels and potassium concentration, were studied. The results from the study indicated that comparatively more assimilates of photosynthesis were allocated to the apex in control plants than in both decapitated and IAA-treated decapitated plants. By contrast, dry matter in the upper leaves, roots, and stems in both decapitated and IAA-treated plants was significantly increased relative to control plants. The potassium level in whole plants decreased post-decapitation compared with control plants, and so did the potassium concentration in middle and upper leaves, stem, and roots. Expression of NKT1, NtKC1, NTORK1, and NKT2 was inhibited by decapitation in tobacco leaves with a gradual reduction after decapitation, but was induced in roots. The relative expression of NKT1, NTORK1, and NKT2 in tobacco leaves was higher than that in roots, whereas the expression of NtKC1 was higher in roots. The levels of inhibition and induction of NKT1, NtKC1, NTORK1, and NKT2 in leaves and roots, respectively, associated with decapitation were reduced by the application of IAA on the cut surface of the decapitated stem. Further results showed that the level of endogenous auxin IAA in decapitated plants, which dropped in leaves and increased in roots by 140.7% at 14 d compared with the control plant, might be attributed to the change in the expression of potassium channel genes. The results suggest that there is a reciprocal relationship among endogenous auxin IAA, expression of potassium channel genes and potassium accumulation. They further imply that the endogenous IAA probably plays a role in regulating the expression of potassium channel genes, and that variations in expression of these genes affected the accumulation and distribution of potassium in tobacco.

  7. The secretory response of parathyroid hormone to acute hypocalcemia in vivo is independent of parathyroid glandular sodium/potassium-ATPase activity

    DEFF Research Database (Denmark)

    Martuseviciene, Giedre; Hofman-Bang, Jacob; Clausen, Torben

    2011-01-01

    The involvement of sodium/potassium-ATPase in regulating parathyroid hormone (PTH) secretion is inferred from in vitro studies. Recently, the α-klotho-dependent rapid recruitment of this ATPase to the parathyroid cell plasma membrane in response to low extracellular calcium ion was suggested......-treated parathyroid glands, indicating inhibition of the ATPase. As ouabain induced systemic hyperkalemia, the effect of high potassium on hormone secretion was also examined but was found to have no effect. Thus, inhibition of the parathyroid gland sodium/potassium-ATPase activity in vivo had no effect...

  8. Transport of Alkali Metal Ions through a Liquid Membrane System ...

    African Journals Online (AJOL)

    crown-6, [K(MF18C6)](picrate) was determined by X-ray crystallography and showed that each potassium ion is eight-coordinate; each K+ ion is coordinated to the six oxygen atoms of the crown, to the phenolate oxygen atom and to one of the ...

  9. Ion-selective organic electrochemical transistors.

    Science.gov (United States)

    Sessolo, Michele; Rivnay, Jonathan; Bandiello, Enrico; Malliaras, George G; Bolink, Henk J

    2014-07-23

    Ion-selective organic electrochemical transistors with sensitivity to potassium approaching 50 μA dec(-1) are demonstrated. The remarkable sensitivity arises from the use of high transconductance devices, where the conducting polymer is in direct contact with a reference gel electrolyte and integrated with an ion-selective membrane. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. ion with phenolate ions

    Indian Academy of Sciences (India)

    Administrator

    Photoinduced electron transfer (PET) reaction of homoleptic tris-chelated polypyridine ruthenium(II) complexes with phenolate ions is sensitive to the structure of the ligand of the Ru(II) complex as well as of the phenolate ions 1. In recent years 2 the photophysical and photochemical properties of Ru(II) complexes based on ...

  11. Potassium permanganate ingestion as a suicide attempt

    Directory of Open Access Journals (Sweden)

    Tuba Cimilli Ozturk

    2012-01-01

    Full Text Available Potassium permanganate is a highly corrosive, water-soluble oxidizing antiseptic. A 68- year-old female patient was admitted to our Emergency Department after ingestion of 3 tablets of 250 mg potassium permanganate as a suicide attempt. The physical exam revealed brown stained lesions in the oropharynx. Emergency endoscopy was performed by the gastroenterologist after the third hour of ingestion. Emergency endoscopy revealed multiple superficial (Grade I-II lesions on the esophagus and cardia, which were considered secondary to the caustic substance. The mainstay in the treatment of potassium permanganate is supportive and the immediate priority is to secure the airway. Emergency endoscopy is an important tool used to evaluate the location and severity of injury to the esophagus, stomach and duodenum after caustic ingestion. Patients with signs and symptoms of intentional ingestion should undergo endoscopy within 12 to 24 h to define the extent of the disease.

  12. Precise coulometric titration of sodium thiosulfate and development of potassium iodate as a redox standard.

    Science.gov (United States)

    Asakai, Toshiaki; Murayama, Mariko; Tanaka, Tatsuhiko

    2007-09-15

    In this paper, we determine the effective purity of potassium iodate as a redox standard with a certified value linked to the international system of units (SI units). Concentration measurement of sodium thiosulfate solution was performed by precise coulometric titration with electrogenerated iodine, and an assay of potassium iodate was carried out by gravimetric titration based on the reductometric factor of sodium thiosulfate assigned by coulometry. The accuracy of the coulometric titration method was evaluated by examining the current efficiency of iodine electrogeneration, stability of sodium thiosulfate solutions and dependence on the amount of sodium thiosulfate solution used. The measurement procedure for gravimetric titration of potassium iodate with sodium thiosulfate was validated based on determination of a reference material of known purity (potassium dichromate determined by coulometry with electrogenerated ferrous ions) using the same gravimetric method. Solutions of 0.2 and 0.5mol/L sodium thiosulfate were stable over 17 days without stabilizer. Investigation of the dependency of titration results on the amount of sodium thiosulfate solution used showed no significant effects, no evidence of diffusion of the sample, and no effect of contamination appearing during the experiment. Precise coulometric titration of sodium thiosulfate achieved a relative standard deviation of less than 0.005% under repeating conditions (six measurements). For gravimetric titration, the results obtained for the effective purity of potassium dichromate were sufficiently close to its certified value to allow confirmation of the validity of the gravimetric titration was confirmed. The relative standard deviation of gravimetric titration for potassium iodate was less than 0.011% (nine measurements), and a redox standard with a certified value linked to SI units was developed.

  13. [The technological progress in haemodialysis: potassium profiling].

    Science.gov (United States)

    Kes, Petar; Racki, Sanjin; Basić-Jukić, Nikolina; Ratković-Gusić, Iva

    2008-01-01

    Patients with the end-stage renal disease often suffer from numerous concomitant diseases. The most common are complications of the cardiovascular system. During the haemodialysis treatment, rapid changes in volume status, osmolality and electrolyte composition of the blood, cause disturbances which manifest as haemodynamic instability, hypotension and cardiac arrhythmias. Especially vulnerable are elderly patients and patients with generalized atherosclerosis, diabetes mellitus, and severe anaemia. Rapid decrease in serum potassium concentration may cause fatal arrhythmias. Contemporary dialysis machines enable slow lowering of potassium concentration during the haemodialysis session (or during the acetate-free biofiltration), what significantly decreases incidence of cardiac arrhythmias and improve cardiovascular stability.

  14. Improved Synthesis Of Potassium Beta' '-Alumina

    Science.gov (United States)

    Williams, Roger M.; Jeffries-Nakamura, Barbara; Ryan, Margaret A.; O'Connor, Dennis E.; Kisor, Adam; Underwood, Mark

    1996-01-01

    Improved formulations of precursor materials synthesize nearly-phase-pure potassium beta' '-alumina solid electrolyte (K-BASE) powder. Materials are microhomogeneous powders (or, alternatively, gels) containing K(+,) Mg(2+), and Al(3+). K-BASE powder produced used in potassium-working-fluid alkali-metal thermal-to-electric conversion (K-AMTEC), in which heat-input and heat-rejection temperatures lower than sodium-working-fluid AMTEC (Na-AMTEC). Additional potential use lies in purification of pottassium by removal of sodium and calcium.

  15. hERG1 potassium channel in cancer cells: a tool to reprogram immortality.

    Science.gov (United States)

    Gentile, Saverio

    2016-10-01

    It has been well established that changes in ion fluxes across cellular membranes as a function of time is fundamental in maintaining cellular homeostasis of every living cell. Consequently, dysregulation of ion channels activity is a critical event in pathological conditions of several tissues, including cancer. Nevertheless, the role of ion channels in cancer biology is still not well understood and very little is known about the possible therapeutic opportunities offered by the use of the vast collection of drugs that target ion channels. In this review, we focus on the recent advances in understanding the role of the voltage-gated hERG1 potassium channel in cancer and on the effects of pharmacologic manipulation of the hERG1 in cancer cells aiming to provide insights into the biochemical signaling and cellular processes that are altered by using these drugs.

  16. Development of a potassium-selective optode for hydroponic nutrient solution monitoring.

    Science.gov (United States)

    Bamsey, Matthew; Berinstain, Alain; Dixon, Michael

    2012-08-06

    Highly efficient and reliable plant growth such as that required in biological life support systems for future space-based missions can be better achieved with knowledge of ion concentrations within the hydroponic nutrient solution. This paper reports on the development and application of ion-selective bulk optodes to plant growth systems. Membranes for potassium-selective sensing are reported that have been tailored so that their dynamic range is centred on potassium activities within typical nutrient solution recipes. The developed sensors have been shown to exhibit a potassium activity measuring range from 0.134 to 117 mM at pH 6.0. These bulk optodes show full scale response on the order of several minutes. They show minimal interference to other cations and meet worst-case selectivity requirements for potassium monitoring in the considered half strength Hoagland solution. When continuously immersed in nutrient solution, these sensors demonstrated predicable lifetimes on the order of 50h. The developed instrument for absorption-based measurements including light source, mini-spectrometer and optode probe is presented. Custom instrument control and monitoring software including a spectral normalization procedure, use of a dual-wavelength absorbance ratio technique and automatic adjustment for pH variation result in an instrument that is self-calibrating and one that can account for effects such as light source fluctuations, membrane thickness variations and a variety of other factors. The low mass, low volume nature of bulk optode sensing systems, make them a promising technology for future space-based plant production systems. Their low-cost and technology transfer potential suggest that they could provide terrestrial growers a new and reliable mechanism to obtain ion-selective knowledge of their nutrient solution, improving yields, reducing costs and aiding in compliance to continually more stringent environmental regulation. Crown Copyright © 2012. Published

  17. Substrate inhibition: Oxidation of D-sorbitol and D-mannitol by potassium periodate in alkaline medium

    Science.gov (United States)

    Lakshman Kumar, Y.; Venkata Nadh, R.; Radhakrishnamurti, P. S.

    2014-05-01

    In the oxidation of D-sorbitol and D-mannitol by potassium periodate in alkaline media, substrate inhibition was observed with both substrates, i.e., a decrease in the rate of the reaction was observed with an increase in the concentration of substrate. The substrate inhibition was attributed to the formation of stable complex between the substrate and periodate. The reactions were found to be first order in case of periodate and a positive fractional order with hydroxide ions. Arrhenius parameters were calculated for the oxidation of sorbitol and mannitol by potassium periodate in alkali media.

  18. Brand to brand variation in the disintegrant functionality of Polacrilin Potassium, NF

    Directory of Open Access Journals (Sweden)

    Mrudula H. Bele

    2011-09-01

    Full Text Available The current monograph for Polacrilin Potassium, NF does not specify tests that could assist in distinguishing between different brands of this disintegrant. The objective of this work was to examine the physical characteristics of four brands of Polacrilin Potassium, NF and relate the observed differences to differences in their functionality. Significant differences were observed in the particle size, true density, porosity, surface area and morphology of the samples. Functionality tests, such as settling volume, intrinsic swelling, rate and extent of water uptake were carried out. Significant differences were observed in intrinsic swelling and the initial rate of water uptake. The disintegration times of the tablets were found to be a function of the initial rate of water uptake. Since the disintegration times were shown to be significantly different despite negligible differences in settling volumes, wicking and water uptake, as opposed to the magnitude of swelling, appear to be the major mechanisms that distinguish disintegration performance between different brands of Polacrilin Potassium, NF when incorporated into insoluble tablet matrices. Thus, the measurement of the rate of water uptake may be a useful functionality test for Polacrilin Potassium in particular, and for ion exchange resin type disintegrants in general.

  19. 186 183 Potassium Bromate Content of Bread

    African Journals Online (AJOL)

    2008-12-02

    Dec 2, 2008 ... This study has shown that in spite of National Agency for Food and Drug Administration and Control. (NAFDAC) campaign for bromate-free ... agents' flavourings, yeasts, and bread improver. Yeast feed on sugar to produce .... mutagenic studies show that potassium bromate is a potential cancer initiator.

  20. METHODS OF AVAILABLE POTASSIUM ASSESSMENT IN ...

    African Journals Online (AJOL)

    AGROSEARCH UIL

    Thus, it is considered important to study methods of available K extraction for better understanding of the ... response to potassium, soil test methods should have a high correlation with crop performance. (Ekpete, 1972). Also ... The bulk samples were air-dried, ground and sieved to pass through 2 mm sieve. Sub samples of.

  1. Photoconductivity and dielectric studies of potassium pentaborate ...

    Indian Academy of Sciences (India)

    Single crystal of potassium pentaborate (KB5) has been grown by solution growth technique. FTIR and laser Raman measurements are carried out to make a qualitative analysis on KB5 crystal. Dielectric behaviour of the KB5 crystal has been studied in the microwave region using K-band microwave bench equipped with ...

  2. 186 183 Potassium Bromate Content of Bread

    African Journals Online (AJOL)

    2008-12-02

    Dec 2, 2008 ... that potassium bromate affects the nutritional quality of bread as the main vitamins available in bread are ... inhalation, abdominal pain, diarrhoea, nausea, vomiting, kidney failure, hearing loss as well as ... because a cancer warning is required on the label (Starr, 2002). The World Health. Organisation in ...

  3. Spectrophotometric Determination of Losartan Potassium in Tablets

    Directory of Open Access Journals (Sweden)

    Arianne Diane A. Aniñon

    2014-06-01

    Full Text Available In the quality control of pharmaceutical products, it is of utmost importance that validated analytical methods are used to ensure the credibility of the results generated. At the time of the study, official monographs from the United States Pharmacopeia and National Formulary (USP-NF for the quantification of Losartan potassium in tablets were unavailable, denoting the need for a validated analytical procedure for the analysis of the drug. The study adapted direct and first-derivative UV spectrophotometry methods proposed by Bonfilio and others (2010 for the assay of Losartan potassium in Losartan 50 mg. capsules, then modified and validated the said procedures for the assay of Losartan potassium in Losartan 100 mg. tablets following the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH guidelines on method validation for accuracy, precision, specificity, linearity, limit of detection, and limit of quantitation. Results demonstrated that all the performance characteristics of both methods were highly satisfactory and confirmed the possible application of the methods in routine analysis of Losartan potassium tablets.

  4. 21 CFR 582.5622 - Potassium chloride.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium chloride. 582.5622 Section 582.5622 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary...

  5. 21 CFR 582.5628 - Potassium glycerophosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium glycerophosphate. 582.5628 Section 582.5628 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or...

  6. 21 CFR 582.5634 - Potassium iodide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium iodide. 582.5634 Section 582.5634 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary...

  7. Acute Renal Failure following Accidental Potassium Bromate ...

    African Journals Online (AJOL)

    Accidental poisoning is common in children. Potassium bromate is a commonly used additive and raising agent in many edibles particularly bread, a staple food worldwide, yet its accidental poisoning has hitherto, not been documented in Nigeria. We report an unusual case of acute renal failure following accidental ...

  8. 21 CFR 172.375 - Potassium iodide.

    Science.gov (United States)

    2010-04-01

    ... added to a food as a source of the essential mineral iodine, provided the maximum intake of the food as... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium iodide. 172.375 Section 172.375 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN...

  9. Nutritional potassium requirement for laying Japanese quails

    Directory of Open Access Journals (Sweden)

    Fernando Guilherme Perazzo Costa

    2011-12-01

    Full Text Available The objective of this study was to evaluate the potassium requirement for laying Japanese quails. Two hundred and forty quails were distributed in a randomized block design, with five treatments and six replicates, with eight birds each. The treatments consisted of a basal diet deficient in potassium (K (2.50 g/kg, supplemented with potassium carbonate, to replace the inert, to reach levels of 2.50, 3.50, 4.50, 5.50 and 6.50 (g/kg of K in the diet. There was a quadratic effect of K levels on feed intake, egg production, egg mass and feed conversion per egg mass and per egg dozen, estimating the requirements of 4.26, 4.41, 4.38, 4.43 and 4.48 (g/kg of K diet, respectively. There was no significant effect on the levels of K in the diet on egg weight, albumen weight, percentage of yolk or shell and yolk color. However, yolk and shell weights reduced and the albumen percentage increased linearly with increasing levels of K in the diet. Despite the reduction of shell weight, the increased levels of K did not influence the specific gravity and shell thickness. The use of 4.41 g/kg of potassium is recommended in the diet for laying Japanese quails.

  10. Acute Renal Failure following Accidental Potassium

    African Journals Online (AJOL)

    . Summary. Okeniyi JAO, Aladekomo TA, Oyelami 0A. Acute Renal Failure following Accidental. Potassium ... Serum Electrvgyte and Urea lef in the Patient '. ' D91 4 Dry 7 D49! ... determination of bromate residues with accuracy in a variety of ...

  11. Effect of potassium on micromorphological and chemical ...

    African Journals Online (AJOL)

    An experiment was conducted at National Agricultural Research Centre (NARC), Islamabad, Pakistan to study the effect of potassium on yield and internal leaf tissues composition of cotton varieties, CIM-443, CIM-109 and CIM-446. Nitrogen (N) and phosphorus (P) were applied at 150 mg N/kg soil and 75 mg P 2O5/kg soil ...

  12. Catalytic decomposition of potassium monopersulfate: the kinetics

    OpenAIRE

    Borralho, Maria Teresa; Gimeno, Olga; RIVAS, Javier; Carbajo, Maria

    2009-01-01

    Potassium monopersulfate has been decomposed in aqueous solution in the presence of Co(II). The process has been simulated by means of a mechanism based on elementary reactions. Rate constants have been taken from literature reports or, alternatively, assimilated to analogous reactions occurring in Fenton´s chemistry. Several operating conditions have been successfully applied.

  13. Qualitative Carbohydrate Analysis using Alkaline Potassium ...

    Indian Academy of Sciences (India)

    IAS Admin

    Carbohydrates form a distinct class of organic compounds often identified by their characteristic behaviour towards a host of reagents [1–4]. Based on a kinetic study on the oxidation of carbohydrates with alkaline potassium ferricyanide [5], we had reported, in the April 2007 issue of Resonance, an unambiguous.

  14. Selective Monohydrocyanation of Diimine using Potassium ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 128; Issue 12. Selective Monohydrocyanation of Diimine using Potassium Hexacyanoferrate(II)-Benzoyl Chloride Reagent System as a Cyanide Source. ZHENG LI FEI WEN JINGYA YANG. Regular Article Volume 128 Issue 12 December 2016 pp 1849-1853 ...

  15. Effect of potassium on micromorphological and chemical ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-08-04

    Aug 4, 2009 ... observed in plant leaves grown without potassium application while in leaves supplied with K their ... available level of its cations in soil and fixation capacity of soil. ... two-third of the total K uptake occurs during a 6-week ...

  16. Relationship Between Extractable Potassium And Phosphorus ...

    African Journals Online (AJOL)

    The effect of laboratory soil sample preparation on level of extractable Potassium (K) and Phosphorus (P) was studied on various soil types collected at Magoebaskloof pine farm (MPF), Tshiombho irrigation scheme (TIS), Dal water farm (DWF) and Syferkuil experimental farm (SEF). Twenty soil samples were collected at ...

  17. Effect Of Virkon Disinfectant Brand Of Potassium ...

    African Journals Online (AJOL)

    In the Nigerian market are many brands of disinfectants with varying efficacy against bacteria, fungi and viruses. Recently Virkon brand of potassium monoperoxysulphate (Antec, UK) was introduced. The Kelsey -Sykes test was carried out to determine the efficacy of Virkon against standard bacterial strains and ...

  18. Theoretical studies of EPR site center for Mn{sup 2+} in potassium thiourea bromide single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, S. [Department of Physics, Gandhigram Rural University, Gandhigram 624302 (India)], E-mail: sravi_phygri@yahoo.com; Subramanian, P. [Department of Physics, Gandhigram Rural University, Gandhigram 624302 (India)], E-mail: psmanian_gri@yahoo.com

    2007-11-01

    The impurity location of Mn{sup 2+} ion in potassium thiourea bromide single crystal is theoretically studied using perturbation formulas of spin Hamiltonian (SH) for 3d{sup 5} ions on strong-field scheme. The spin Hamiltonian parameter values are calculated by this technique. The g and A factors are in reasonable agreement with the experimental results. The zero-field splitting parameter is calculated as 775x10{sup -4} cm{sup -1}. The impurity ion Mn{sup 2+} undergoes off-center displacement of about 0.38 A. The results are discussed.

  19. Determinants of renal potassium excretion in critically ill patients : The role of insulin therapy

    NARCIS (Netherlands)

    Hoekstra, Miriam; Yeh, Lu; Oude Lansink, Annemieke; Vogelzang, Mathijs; Stegeman, Coen A.; Rodgers, Michael G. G.; van der Horst, Iwan C. C.; Wietasch, Gotz; Zijlstra, Felix; Nijsten, Maarten W. N.

    Objectives: Insulin administration lowers plasma potassium concentration by augmenting intracellular uptake of potassium. The effect of insulin administration on renal potassium excretion is unclear. Some studies suggest that insulin has an antikaliuretic effect although plasma potassium levels were

  20. 21 CFR 582.1129 - Aluminum potassium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum potassium sulfate. 582.1129 Section 582.1129 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Additives § 582.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of...

  1. 21 CFR 182.1129 - Aluminum potassium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum potassium sulfate. 182.1129 Section 182.1129 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b...

  2. Development of a new photorefractive and photovoltaic potassium niobate crystal

    Science.gov (United States)

    Evans, D. R.; Basun, S. A.; Seim, J. M.

    2005-03-01

    Photovoltaic measurements have been made on a new doped potassium niobate crystal that yields significantly larger photovoltaic fields than other doped potassium niobate crystals. Contra-directional two-beam coupling efficiencies and Raman spectroscopy measurements have also been conducted, which show major differences with respect to the published results for other doped potassium niobate materials.

  3. 21 CFR 184.1077 - Potassium acid tartrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium acid tartrate. 184.1077 Section 184.1077... Listing of Specific Substances Affirmed as GRAS § 184.1077 Potassium acid tartrate. (a) Potassium acid... accordance with § 184.1(b)(1), the ingredient is used in food with no limitation other than current good...

  4. 40 CFR 721.10031 - Lithium potassium titanium oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lithium potassium titanium oxide. 721... Substances § 721.10031 Lithium potassium titanium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lithium potassium titanium oxide (PMN P-02...

  5. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium nitrate are subject to prior sanctions issued by the U.S. Department of Agriculture for use as sources of...

  6. PHOSPHORUS-POTASSIUM AND NITROGEN-PHOSPHORUS-POTASSIUM FERTILIZER BASED ON WASHED AND DRIED CONCENTRATE FROM CENTRAL KYZYLKUM PHOSPHORITE

    OpenAIRE

    NAZIROVA RAXNAMO MUXTAROVNA; TADJIEV SAYFUDDIN MUKHTAROVICH; TUKHTAYEV SAYDIAXRAL

    2016-01-01

    In this article the findings on the production of complex phosphorus-potassium and nitrogen-phosphorus-potassium fertilizer by decomposition of washed and dried phosphoconcentrate from Central Kyzylkum phosphorite with incomplete norms of sulfuric acid with the addition of potassium chloride, sulfate, ammonium nitrate and urea have been given. It has been revealed that the addition of potassium chloride and ammonium salts significantly affect on expansion coefficient and NP and NPK fertilizer...

  7. Changes in ion transport in inflammatory disease

    Directory of Open Access Journals (Sweden)

    Eisenhut Michael

    2006-03-01

    Full Text Available Abstract Ion transport is essential for maintenance of transmembranous and transcellular electric potential, fluid transport and cellular volume. Disturbance of ion transport has been associated with cellular dysfunction, intra and extracellular edema and abnormalities of epithelial surface liquid volume. There is increasing evidence that conditions characterized by an intense local or systemic inflammatory response are associated with abnormal ion transport. This abnormal ion transport has been involved in the pathogenesis of conditions like hypovolemia due to fluid losses, hyponatremia and hypokalemia in diarrhoeal diseases, electrolyte abnormalites in pyelonephritis of early infancy, septicemia induced pulmonary edema, and in hypersecretion and edema induced by inflammatory reactions of the mucosa of the upper respiratory tract. Components of membranous ion transport systems, which have been shown to undergo a change in function during an inflammatory response include the sodium potassium ATPase, the epithelial sodium channel, the Cystic Fibrosis Transmembrane Conductance Regulator and calcium activated chloride channels and the sodium potassium chloride co-transporter. Inflammatory mediators, which influence ion transport are tumor necrosis factor, gamma interferon, interleukins, transforming growth factor, leukotrienes and bradykinin. They trigger the release of specific messengers like prostaglandins, nitric oxide and histamine which alter ion transport system function through specific receptors, intracellular second messengers and protein kinases. This review summarizes data on in vivo measurements of changes in ion transport in acute inflammatory conditions and in vitro studies, which have explored the underlying mechanisms. Potential interventions directed at a correction of the observed abnormalities are discussed.

  8. Determination of trimethylselenonium ion in urine by ion chromatography and inductively coupled plasma mass spectrometry detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jessen, K.D.; Kristensen, F.H.

    2000-01-01

    The selenium species selenite, selenate, selenomethionine (SeMet), and trimethylselenonium iodide (TMSe+) were separated in aqueous solution by ion chromatography. The separation was performed on an Ionpac CS5 cation exchange column by elution with 10 mM oxalic acid and 20 mM potassium sulphate, p...

  9. Physicochemical action of potassium-magnesium citrate in nephrolithiasis

    Science.gov (United States)

    Pak, C. Y.; Koenig, K.; Khan, R.; Haynes, S.; Padalino, P.

    1992-01-01

    Effect of potassium-magnesium citrate on urinary biochemistry and crystallization of stone-forming salts was compared with that of potassium citrate at same dose of potassium in five normal subjects and five patients with calcium nephrolithiasis. Compared to the placebo phase, urinary pH rose significantly from 6.06 +/- 0.27 to 6.48 +/- 0.36 (mean +/- SD, p less than 0.0167) during treatment with potassium citrate (50 mEq/day for 7 days) and to 6.68 +/- 0.31 during therapy with potassium-magnesium citrate (containing 49 mEq K, 24.5 mEq Mg, and 73.5 mEq citrate per day). Urinary pH was significantly higher during potassium-magnesium citrate than during potassium citrate therapy. Thus, the amount of undissociated uric acid declined from 118 +/- 61 mg/day during the placebo phase to 68 +/- 54 mg/day during potassium citrate treatment and, more prominently, to 41 +/- 46 mg/day during potassium-magnesium citrate therapy. Urinary magnesium rose significantly from 102 +/- 25 to 146 +/- 37 mg/day during potassium-magnesium citrate therapy but not during potassium citrate therapy. Urinary citrate rose more prominently during potassium-magnesium citrate therapy (to 1027 +/- 478 mg/day from 638 +/- 252 mg/day) than during potassium citrate treatment (to 932 +/- 297 mg/day). Consequently, urinary saturation (activity product) of calcium oxalate declined significantly (from 1.49 x 10(-8) to 1.03 x 10(-8) M2) during potassium-magnesium citrate therapy and marginally (to 1.14 x 10(-8) M2) during potassium citrate therapy.(ABSTRACT TRUNCATED AT 250 WORDS).

  10. Effects of cisplatin on potassium currents in CT26 cells

    Directory of Open Access Journals (Sweden)

    Naveen Sharma

    2016-01-01

    Conclusion: Potassium currents were detected in CT26 cells and the currents were reduced by the application of tetraethylammonium (TEA chloride, iberiotoxin, a big conductance calcium-activated potassium channel blocker and barium. The potassium currents were enhanced to 192< by the application of cisplatin (0.5 mM. Moreover, the increase of potassium currents by cisplatin was further inhibited by the application of TEA confirming the action of cisplatin on potassium channels. In addition, relative current induced by cisplatin in CT26 cells was bit larger than in normal IEC-6 cells.

  11. The solubilization of tetrameric alkaline phosphatase from human liver and its conversion into various forms by phosphatidylinositol phospholipase C or proteolysis.

    Science.gov (United States)

    Hawrylak, K; Stinson, R A

    1988-10-05

    When membrane-bound human liver alkaline phosphatase was treated with a phosphatidylinositol (PI) phospholipase C obtained from Bacillus cereus, or with the proteases ficin and bromelain, the enzyme released was dimeric. Butanol extraction of the plasma membranes at pH 7.6 yielded a water-soluble, aggregated form that PI phospholipase C could also convert to dimers. When the membrane-bound enzyme was solubilized with a non-ionic detergent (Nonidet P-40), it had the Mr of a tetramer; this, too, was convertible to dimers with PI phospholipase C or a protease. Butanol extraction of whole liver tissue at pH 6.6 and subsequent purification yielded a dimeric enzyme on electrophoresis under nondenaturing conditions, whereas butanol extraction at pH values of 7.6 or above and subsequent purification by immunoaffinity chromatography yielded an enzyme with a native Mr twice that of the dimeric form. This high molecular weight form showed a single Coomassie-stained band (Mr = 83,000) on electrophoresis under denaturing conditions in sodium dodecyl sulfate, as did its PI phospholipase C cleaved product; this Mr was the same as that obtained with the enzyme purified from whole liver using butanol extraction at pH 6.6. These results are highly suggestive of the presence of a butanol-activated endogenous enzyme activity (possibly a phospholipase) that is optimally active at an acidic pH. Inhibition of this activity by maintaining an alkaline pH during extraction and purification results in a tetrameric enzyme. Alkaline phosphatase, whether released by phosphatidylinositol (PI) phospholipase C or protease treatment of intact plasma membranes, or purified in a dimeric form, would not adsorb to a hydrophobic medium. PI phospholipase C treatment of alkaline phosphatase solubilized from plasma membranes by either detergent or butanol at pH 7.6 yielded a dimeric enzyme that did not absorb to the hydrophobic medium, whereas the untreated preparations did. This adsorbed activity was

  12. MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS

    Energy Technology Data Exchange (ETDEWEB)

    Nash, C.; Hang, T.; Aleman, S.

    2011-01-03

    Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.

  13. Potassium tetracyanidoaurate(III monohydrate: a redetermination

    Directory of Open Access Journals (Sweden)

    Nobuyuki Matsushita

    2017-03-01

    Full Text Available The structure of the title metal complex salt, K[Au(CN4]·H2O, has been redetermined using X-ray diffraction data at 173 K in order to improve the precision. The previous determination was based on neutron diffraction data [Bertinotti & Bertinotti (1970. Acta Cryst. B26, 422–428]. The title compound crystallizes in the space group P212121 with one potassium cation, one [Au(CN4]− anion and one water molecule in the asymmetric unit. The AuIII atom lies on a general position and has an almost square-planar coordination sphere defined by four cyanide ligands. Interactions between the potassium cation and N atoms of the complex anion, as well as O—H...N hydrogen bonds, lead to the formation of a three-dimensional framework structure.

  14. A potassium sensor based on non-covalent functionalization of multi-walled carbon nanotubes.

    Science.gov (United States)

    Parra, Enrique J; Rius, F Xavier; Blondeau, Pascal

    2013-05-07

    Non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs) by a pyrene based benzo-18-crown-6 ether 1 leads to nanostructure assemblies that play both the role of an ion-to-electron transducer and a selective recognition element in solid-contact ion-selective-electrodes (SC-ISEs). The high loading capacity (36 wt%) as well as the suitable dispersion character of the MWCNT hybrid in the ion-selective membrane (ISM) confirmed the benefit of this approach over the covalent one. The sensor has been applied successfully to the detection of potassium. Nernstian response (56.9 ± 0.9 mV per decade) was obtained (10(-5) and 10(-2) M K(+)) and the selectivity pattern was not altered by the immobilization of the ionophore on the MWCNTs. Leakage of the ionophore from the polymeric matrix is therefore avoided while the sensor construction was simplified and the analytical performances were maintained.

  15. Function of Shaker potassium channels produced by cell-free translation upon injection into Xenopus oocytes.

    Science.gov (United States)

    Jarecki, Brian W; Makino, Shin-ichi; Beebe, Emily T; Fox, Brian G; Chanda, Baron

    2013-01-01

    Voltage-gated ion channels are a class of membrane proteins that temporally orchestrate the ion flux critical for chemical and electrical signaling in excitable cells. Current methods to investigate the function of these channels rely on heterologous expression in living systems or reconstitution into artificial membranes; however these approaches have inherent drawbacks which limit potential biophysical applications. Here, we describe a new integrated approach combining cell-free translation of membrane proteins and in vivo expression using Xenopus laevis oocytes. In this method, proteoliposomes containing Shaker potassium channels are synthesized in vitro and injected into the oocytes, yielding functional preparations as shown by electrophysiological and fluorescence measurements within few hours. This strategy for studying eukaryotic ion channels is contrasted with existing, laborious procedures that require membrane protein extraction and reconstitution into synthetic lipid systems.

  16. Non-destructive measurement of calcium and potassium in apple and pear using handheld x-ray fluorescence

    Directory of Open Access Journals (Sweden)

    Lee A Kalcsits

    2016-04-01

    Full Text Available Calcium and potassium are essential for cell signalling, ion homeostasis and cell wall strength in plants. Unlike nutrients such as nitrogen and potassium, calcium is immobile in plants. Localized calcium deficiencies result in agricultural losses; particularly for fleshy horticultural crops in which elemental imbalances in fruit contribute to the development of physiological disorders such as bitter pit in apple and cork spot in pear. Currently, elemental analysis of plant tissue is destructive, time consuming and costly. This is a limitation for nutrition studies related to calcium in plants. Handheld portable x-ray fluorescence (XRF can be used to non-destructively measure elemental concentrations. The main objective was to test if handheld XRF can be used for semi-quantitative calcium and potassium analysis of in-tact apple and pear. Semi-quantitative measurements for individual fruit were compared to results obtained from traditional lab analysis. Here, we observed significant correlations between handheld XRF measurements of calcium and potassium and concentrations determined using MP-AES lab analysis. Pearson correlation coefficients ranged from 0.73 and 0.97. Furthermore, measuring apple and pear using handheld XRF identified spatial variability in calcium and potassium concentrations on the surface of individual fruit. This variability may contribute to the development of localized nutritional imbalances. This highlights the importance of understanding spatial and temporal variability in elemental concentrations in plant tissue. Handheld XRF is a relatively high-throughput approach for measuring calcium and potassium in plant tissue. It can be used in conjunction with traditional lab analysis to better understand spatial and temporal patterns in calcium and potassium uptake and distribution within an organ, plant or across the landscape.

  17. Potassium Permanganate Poisoning: A Nonfatal Outcome

    Directory of Open Access Journals (Sweden)

    Suzan M. Eteiwi

    2015-07-01

    Full Text Available Acute poisoning by potassium permanganate is a rare condition with high morbidity and mortality. Diagnosis of the condition relies on a history of exposure or ingestion and a high degree of clinical suspicion. Oxygen desaturation and the presence of methemoglobin are also helpful indicators. Since no specific antidote is available, treatment is mainly supportive. Few cases have been reported in the literature following potassium permanganate ingestion, whether intentional or accidental, and most of the patients in these cases had unfavorable outcomes, which was not the case in our patient. Our patient, a 73-year-old male, purchased potassium permanganate over the counter mistaking it for magnesium salt, which he frequently used as a laxative. Several hours after he ingested it, he was admitted to the endocrine department at King Hussein Medical Center, Jordan, with acute rapidly evolving shortness of breath. During hospitalization, his liver function tests deteriorated. Since he was diagnosed early and managed promptly he had a favorable outcome.

  18. In vitro effect of pH on resistance of ruminal bacteria to intracellular potassium depletion, and effect of pH and ionophores on ammonia and microbial protein production Efeito do pH in vitro sobre a resistência de bactérias do rúmen à perda de potássio intracelular e efeito do pH e de ionóforos sobre a produção de amônia e proteína microbiana

    Directory of Open Access Journals (Sweden)

    W.M. Leopoldino

    2005-12-01

    Full Text Available Ruminal fluid from steers fed on pasture was incubated with artificial media at pH 5.5 and 7.0 in two experiments. In the first, the effect of monensin level on resistance of ruminal bacteria to potassium depletion was evaluated; in the second, effects of the ionophores monensin and lasalocid on ammonia and protein production were quantified. In experiment 1, culture media affected potassium level. The monensin concentration needed to cause half maximal potassium depletion was 2.77µM at pH 5.5 but was 0.056µM at pH 7.0, showing that bacteria incubated at pH 5.5 were more tolerant to monensin than those incubated at pH 7.0. Both ionophores as well as increased acidity caused decreased ammonia production. Both ionophores inhibited ammonia production by 56%, independently of pH. In cultures incubated at pH 5.5 compared to pH 7.0, ammonia production was decreased by 50.5%, independently of the ionophores. Therefore, effects of ionophores and acidity were additive, and the maximum inhibition occurred in the presence of an ionophore at low pH (75.2%. Microbial protein production was lowest when lasalocid was present in a low pH culture medium, causing inhibition of microbial growth.Em dois estudos, o líquido ruminal de bovinos mantidos sob pastagem foi usado para incubação in vitro em diferentes meios artificiais com valores de pH 5,5 e 7,0, para avaliar a ação de níveis crescentes de monensina na resistência à perda de potássio de bactérias do rúmen e verificar o efeito de monensina e lasalocida na produção de amônia e de proteína microbiana em pH 5,5 e 7,0. O meio utilizado para determinar a perda de potássio interferiu nos valores absolutos de potássio. A concentração de monensina necessária para causar a metade da perda máxima de potássio foi de 2,77µM em pH 5,5 e 0,056µM em pH 7,0, evidenciando que as bactérias incubadas em meios com pH 5,5 foram mais resistentes à monensina que aquelas incubadas em meios com pH 7

  19. Race, Serum Potassium, and Associations With ESRD and Mortality.

    Science.gov (United States)

    Chen, Yan; Sang, Yingying; Ballew, Shoshana H; Tin, Adrienne; Chang, Alex R; Matsushita, Kunihiro; Coresh, Josef; Kalantar-Zadeh, Kamyar; Molnar, Miklos Z; Grams, Morgan E

    2017-08-01

    Recent studies suggest that potassium levels may differ by race. The basis for these differences and whether associations between potassium levels and adverse outcomes differ by race are unknown. Observational study. Associations between race and potassium level and the interaction of race and potassium level with outcomes were investigated in the Racial and Cardiovascular Risk Anomalies in Chronic Kidney Disease (RCAV) Study, a cohort of US veterans (N=2,662,462). Associations between African ancestry and potassium level were investigated in African Americans in the Atherosclerosis Risk in Communities (ARIC) Study (N=3,450). Race (African American vs non-African American and percent African ancestry) for cross-sectional analysis; serum potassium level for longitudinal analysis. Potassium level for cross-sectional analysis; mortality and end-stage renal disease for longitudinal analysis. The RCAV cohort was 18% African American (N=470,985). Potassium levels on average were 0.162mmol/L lower in African Americans compared with non-African Americans, with differences persisting after adjustment for demographics, comorbid conditions, and potassium-altering medication use. In the ARIC Study, higher African ancestry was related to lower potassium levels (-0.027mmol/L per each 10% African ancestry). In both race groups, higher and lower potassium levels were associated with mortality. Compared to potassium level of 4.2mmol/L, mortality risk associated with lower potassium levels was lower in African Americans versus non-African Americans, whereas mortality risk associated with higher levels was slightly greater. Risk relationships between potassium and end-stage renal disease were weaker, with no difference by race. No data for potassium intake. African Americans had slightly lower serum potassium levels than non-African Americans. Consistent associations between potassium levels and percent African ancestry may suggest a genetic component to these differences. Higher and

  20. Isohydric regulation of plasma potassium by bicarbonate in the rat.

    Science.gov (United States)

    Fraley, D S; Adler, S

    1976-04-01

    pH and bicarbonate affect many metabolic reactions but each may change independently. To study bicarbonate's effect onplasma potassium, blood bicarbonate in normal, hypokalemic or hyperkalemic rats was either maintained constant, lowered by hydrochloric acid or raised by sodium bicarbonate administraion. Blood pH was maintained constant by changing PCO2. In normokalemia lowering bicarbonate increased plasma potassium 2.0mEq above values obtained in the other groups. To eliminate urinary potassium losses, experiments were also performed in rats with bilateral ureteral ligation. Again, plasma potassium concentration rose significantly more in the lowered bicarbonate group. Similarly, in hypokalemia, plasma potassium rose 1.2 and 0.4mEq in the lowered and unchanged groups, but fell 0.2mEq/liter in the elevated group. Differences could not be ascribed to renal potassium losses as potassium excretion was essentially zero in each group. In hyperkalemia, plasma potassium concentration remained elevated for 150 min in the lowered bicarbonate group but fell 1.3 and 2.0mEq in the unchanged and elevated groups, respectively. Urinary potassium losses in the three groups were statistically identical. In all experiments blood pH was maintained unchanged during the experiment. The data show that bicarbonate, independent of blood pH, alters transcellular potassium distribution suggesting the usefulness of bicarbonate therapy in hyperkalemia even at a compensated blood pH.

  1. Cation-Anion Balance during Potassium and Sodium Absorption by Barley Roots

    Science.gov (United States)

    Jackson, P. C.; Adams, H. R.

    1963-01-01

    Steady-state rates of potassium ion and sodium ion absorption by excised barley roots accompanied by various anions were compared with the rates of anion absorption and the concomitant H+ and base release by the roots. The cation absorption rates were found to be independent of the identities, concentrations, and rates of absorption of the anions of the external solution, including bicarbonate. Absorption of the anion of the salt plus bicarbonate could not account for the cation absorption. H+ is released during cation absorption and base during anion absorption. The magnitude by which one or the other predominates depends on the relative rates of anion and cation absorption under various conditions of pH, cation and anion concentration, and inhibitor concentrations. The conclusion is that potassium and sodium ions are absorbed independently of the anions of the absorption solution in exchange for H+, while anions are exchanged for a base. The H+ release reflects a specificity between K+ and Na+ absorption such that it appears to be H+ exchanged in the specific rate-limiting reactions of the cation absorption. PMID:13964256

  2. Mapping the fundamental niches of two freshwater microalgae, Chlorella vulgaris (Trebouxiophyceae) and Peridinium cinctum (Dinophyceae), in 5-dimensional ion space

    Science.gov (United States)

    A five dimensional experimental design, i.e. a five component ion mixture design for nitrate, phosphate, potassium, sodium and chloride projected across a total ion concentration gradient of 1-30 mM was utilized to map the ion-based, scenopoetic, or ‘Grinnellian’, niche space for two freshwater alga...

  3. Multi-stage inhibition in breast cancer metastasis by orally active triple conjugate, LHTD4 (low molecular weight heparin-taurocholate-tetrameric deoxycholate).

    Science.gov (United States)

    Alam, Farzana; Al-Hilal, Taslim A; Park, Jooho; Choi, Jeong Uk; Mahmud, Foyez; Jeong, Jee-Heon; Kim, In-San; Kim, Sang Yoon; Hwang, Seung Rim; Byun, Youngro

    2016-04-01

    Targeting multiple stages in metastatic breast cancer is one of the effective ways to inhibit metastatic progression. To target human metastatic breast cancer as well as improving patient compliance, we developed an orally active low molecular weight heparin (LMWH)-taurocholate conjugated with tetrameric deoxycholic acid, namely LHTD4, which followed by physical complexation with a synthetic bile acid enhancer, DCK. In breast cancer, both transforming growth factor-β1 (TGF-β1) and CXCL12 exhibit enhanced metastatic activity during the initiation and progression stages of breast cancer, thus we direct the focus on investigating the antimetastatic effect of LHTD4/DCK complex by targeting TGF-β1 and CXCL12. Computer simulation study and SPR analysis were performed for the binding confirmation of LHTD4 with TGF-β1 and CXCL12. We carried out in vitro phosphorylation assays of the consecutive receptors of TGF-β1 and CXCL12 (TGF-β1R1 and CXCR4, respectively). Effects of LHTD4 on in vitro cell migration (induced by TGF-β1) and chemotaxis (mediated by CXCL12) were investigated. The in vivo anti-metastatic effect of LHTD4 was evaluated in an accelerated metastasis model and an orthotopic MDA-MB-231 breast cancer model. The obtained KD values of TGF-β1 and CXCL12 with LHTD4 were 0.85 and 0.019 μM respectively. The simulation study showed that binding affinities of LHTD4 fragment with either TGF-β1 or CXCL12 through additional electrostatic interaction was more stable than that of LMWH fragment. In vitro phosphorylation assays of TGF-β1R1 and CXCR4 showed that the effective inhibition of receptor phosphorylation was observed with the treatment of LHTD4. The expressions of epithelial to mesenchymal transition (EMT) marker proteins such as vimentin and Snail were prevented by LTHD4 treatment in in vitro studies with TGF-β1 treated MDA-MB-231 cells. Moreover, we observed that LHTD4 negatively regulated the functions of TGF-β1 and CXCL12 on migration and

  4. Activation of human ether-a-go-go-related gene potassium channels by the diphenylurea 1,3-bis-(2-hydroxy-5-trifluoromethyl-phenyl)-urea (NS1643)

    DEFF Research Database (Denmark)

    Hansen, Rie Schultz; Diness, Thomas Goldin; Christ, Torsten

    2005-01-01

    The cardiac action potential is generated by a concerted action of different ion channels and transporters. Dysfunction of any of these membrane proteins can give rise to cardiac arrhythmias, which is particularly true for the repolarizing potassium channels. We suggest that an increased repolari...

  5. Quartz crystal microbalance sensor using ionophore for ammonium ion detection.

    Science.gov (United States)

    Kosaki, Yasuhiro; Takano, Kosuke; Citterio, Daniel; Suzuki, Koji; Shiratori, Seimei

    2012-01-01

    Ionophore-based quartz crystal microbalance (QCM) ammonium ion sensors with a detection limit for ammonium ion concentrations as low as 2.2 microM were fabricated. Ionophores are molecules, which selectively bind a particular ion. In this study, one of the known ionophores for ammonium, nonactin, was used to detect ammonium ions for environmental in-situ monitoring of aquarium water for the first time. To fabricate the sensing films, poly(vinyl chloride) was used as the matrix for the immobilization of nonactin. Furthermore, the anionic additive, tetrakis (4-chlorophenyl) borate potassium salt and the plasticizer dioctyl sebacate were used to enhance the sensor properties. The sensor allowed detecting ammonium ions not only in static solution, but also in flowing water. The sensor showed a nearly linear response with the increase of the ammonium ion concentration. The QCM resonance frequency increased with the increase of ammonium ion concentration, suggesting a decreasing weight of the sensing film. The detailed response mechanism could not be verified yet. However, from the results obtained when using a different plasticizer, nitrophenyl octyl ether, it is considered that this effect is caused by the release of water molecules. Consequently, the newly fabricated sensor detects ammonium ions by discharge of water. It shows high selectivity over potassium and sodium ions. We conclude that the newly fabricated sensor can be applied for detecting ammonium ions in aquarium water, since it allows measuring low ammonium ion concentrations. This sensor will be usable for water quality monitoring and controlling.

  6. Highly accelerated lifetime testing of potassium sodium niobate thin films

    Science.gov (United States)

    Zhu, Wanlin; Akkopru-Akgun, Betul; Trolier-McKinstry, Susan

    2017-11-01

    Highly accelerated lifetime tests of 2 and 3 μm thick potassium sodium niobate [(K0.5, Na0.5)NbO3, KNN] films with different thicknesses were measured under electric fields ranging from 160 to 350 kV/cm and temperatures ranging from 90 to 210 °C. The medium time to failure (t50) was determined from a lognormal distribution plot of failure times of up to 22 electrodes per measurement condition. The activation energy (Ea) for failure was 0.74 ± 0.04 eV and 0.92 ± 0.05 eV for the 2 μm and 3 μm KNN films, respectively. The voltage acceleration factor was 3.5 ± 0.34 for the 3 μm film. But the electric field dependence of t50 for the 2 μm film showed two regions with similar N, 6.67 and 6.94 ± 0.23, respectively. Energy-dispersive X-ray spectroscopy was employed to investigate the Na+ and K+ ion distributions in KNN films.

  7. Potassium Channels in Motor Cells of Samanea saman1

    Science.gov (United States)

    Moran, Nava; Ehrenstein, Gerald; Iwasa, Kunihiko; Mischke, Charles; Bare, Charles; Satter, Ruth L.

    1988-01-01

    Leaflet movements in Samanea saman are driven by the shrinking and swelling of cells in opposing (extensor and flexor) regions of the motor organ (pulvinus). Changes in cell volume, in turn, depend upon large changes in motor cell content of K+, Cl− and other ions. We performed patch-clamp experiments on extensor and flexor protoplasts, to determine whether their plasma membranes contain channels capable of carrying the large K+ currents that flow during leaflet movement. Recordings in the “whole-cell” mode reveal depolarization-activated K+ currents in extensor and flexor cells that increase slowly (t½ = ca. 2 seconds) and remain active for minutes. Recordings from excised patches reveal a single channel conductance of ca. 20 picosiemens in both cell types. The magnitude of the K+ currents is adequate to account quantitatively for K+ loss, previously measured in vivo during cell shrinkage. The K+ channel blockers tetraethylammonium (5 millimolar) or quinine (1 millimolar) blocked channel opening and decreased light- and dark-promoted movements of excised leaflets. These results provide evidence for the role of potassium channels in leaflet movement. Images Fig. 4 PMID:16666362

  8. Cefadroxil iodometric determination by potassium hydrogenperoxomonosulfate reaction

    Directory of Open Access Journals (Sweden)

    Юлія Юріївна Сердюкова

    2015-10-01

    Full Text Available Aim. Simple methods of oxidimetric determination of β-lactam antibiotic cefadroxil in pure powder and in capsules, that are based on S-oxidation reactions by potassium hydrogenperoxomonosulphate acid in weak acid medium to S- oxide with following iodometric quantitative determination of the oxydator reagent excess were developed.Materials and methods. A triple potassium salt of caroate acid, 2KHSO5•KHSO4•K2SO4 (commercial «Oxone®» DuPont, production was used as oxidizing agent.Results. By the results of reaction kinetics using iodometric titration it was determined that redox reaction between cefadroxil and potassium hydrogenperoxomonosulfate is quantified and a stoichiometric: 1 mol of cefadroxil is per 1 mol of potassium hydrogen. Quantitative oxidation of Sulfur atom was finished in the time that is less than 1 min. The mean recovery of the main substance in the cefadroxil pure substance was 97.76%, RSD=1.33 % (δ=1.31 %, 1 mL of the standard 0.0200 mol L-1 sodium tiosulphate solution corresponds to 0.003634 g of sodium cefadroxil (C16H17N3O5S which should be 95–102 % in the pure anhydrous substance. The mean recovery of medical preparation “Cefadroxil”, 500 mg is 100.06 %, RSD=0.96 % (δ=1.01 %, which should be 92.5–107.5 %, in anhydrous preparation. The limit detection is С=0.05 mg mL-1. The advantages of the proposed procedure are the ability to assay cefadroxil by the biologically active part of the molecule (alicyclic and tiomethyl sulfur, good recovery and the accuracy of results.Conclusions. The obtained validation data meet the requirements of the State Pharmacopoeia of Ukraine, which indicates the possibility of its introduction in the practice of analytical laboratories analysis, or application during the stepwise control process or manufacturing of drugs quality control during equipment washing

  9. Pore size matters for potassium channel conductance

    Science.gov (United States)

    Moldenhauer, Hans; Pincuntureo, Matías

    2016-01-01

    Ion channels are membrane proteins that mediate efficient ion transport across the hydrophobic core of cell membranes, an unlikely process in their absence. K+ channels discriminate K+ over cations with similar radii with extraordinary selectivity and display a wide diversity of ion transport rates, covering differences of two orders of magnitude in unitary conductance. The pore domains of large- and small-conductance K+ channels share a general architectural design comprising a conserved narrow selectivity filter, which forms intimate interactions with permeant ions, flanked by two wider vestibules toward the internal and external openings. In large-conductance K+ channels, the inner vestibule is wide, whereas in small-conductance channels it is narrow. Here we raise the idea that the physical dimensions of the hydrophobic internal vestibule limit ion transport in K+ channels, accounting for their diversity in unitary conductance. PMID:27619418

  10. Modeling removal of accumulated potassium from T-tubules by inward rectifier potassium channels

    NARCIS (Netherlands)

    Wallinga, W.; Vliek, M.; Wienk, E.D.; Alberink, M.J.; Ypey, D.L.; Ypey, D.L.

    1996-01-01

    The membrane models of Cannon et al. (1993) and Alberink et al. (1995) for mammalian skeletal muscle fibers are based upon Hodgkin-Huxley descriptions of sodium, potassium delayed rectifier and leak conductances and the capacitive current taking into account fast inactivation of sodium channels. Now

  11. Expression of the two pore domain potassium channel TREK-1 in human intervertebral disc cells.

    Science.gov (United States)

    Sharma, Pankaj; Hughes, Stephen; El Haj, Alicia; Maffulli, Nicola

    2012-07-01

    Potassium channels play a major role in intracellular homeostasis and regulation of cell volume. Intervertebral disc cells respond to mechanical loading in a complex manner. Mechanical loading may play a role in disc degeneration. Lumbar intervertebral disc samples from 5 patients (average age: 47 years, range: 25-64 years) were used for this study, investigating cells from the nucleus pulposus and the annulus fibrosus duplicate samples to determine RNA expression and protein expression. Analysis of mRNA expression by RT-PCR demonstrated that TREK 1 was expressed by nucleus pulposus (n=5) and annulus fibrosus (n=5) cells. Currently, TREK-1 is the only potassium channel known to be activated by intracellular acidosis, and responds to mechanical and chemical stimuli. Whilst the precise role of potassium channels in cellular homeostasis remains to be determined, TREK-1 may be important to protect disc cells against ischaemic damage, and subsequent disc degeneration, and may also play a role in effecting mechanotransduction. Further research is required to fully elucidate the role of the TREK-1 ion channel in intervertebral disc cells.

  12. Synthesis of Analcime Crystals and Simultaneous Potassium Extraction from Natrolite Syenite

    Directory of Open Access Journals (Sweden)

    Jian Chen

    2017-01-01

    Full Text Available Analcime single crystals were successfully synthesized from natrolite syenite powder (K2O 10.89% and 92.6% of potassium was extracted simultaneously by means of soda roasting followed by alkali-hydrothermal method. Effects of NaOH concentration, reaction temperature, and holding period on the analcime formation and potassium extraction were investigated systemically. The results indicated that NaOH concentration plays an important role in determining the chemical composition of zeolites and size distribution; by turning the NaOH concentrations, three different pure zeolites (i.e., the phillipsite-Na, the analcime, and the sodalite were prepared. Besides, a higher temperature could accelerate the dissolution of K+ ions and enhance the crystallinity degree of zeolite. The reactions involved in the analcime synthesis can be summarized as follows: sodium aluminum silicate dissolution → precipitation and dissolution of metastable zeolite-P → analcime nucleation → analcime growth. The extraction ratio of K+ is associated with the types of synthesized zeolites, among which analcime is the most effective to promote potassium leaching out from zeolite lattice position. The optimal condition for analcime crystallization and K+ leaching is found to be as follows: 175°C for 4 h in 0.5 mol/L NaOH solution.

  13. Simultaneous determination of tartaric acid and potassium in wines using a multicommuted flow system with dialysis.

    Science.gov (United States)

    Oliveira, Sara M; Lopes, Teresa I M S; Tóth, Ildikó V; Rangel, António O S S

    2010-06-15

    A multicommuted flow system with the propulsion device placed before detection is proposed for the determination of tartaric acid and free potassium in table and Port wines. A dialysis unit was introduced to increase sample dilution and minimize matrix interferences. The determination of tartaric acid was based on the spectrophotometric monitorization of the complex formed by the dialyzed analyte with vanadate. Potentiometric measurement of potassium was carried out through an ion selective tubular electrode. Dynamic linear ranges of 0.500-5.00gL(-1) and 390-2000mgL(-1) were achieved for tartaric acid and potassium determinations, respectively. Detection and quantification limits of 0.1 and 0.4gL(-1) of tartaric acid were obtained, respectively. For the potentiometric determination, a detection limit of 1x10(-4)molL(-1) was achieved. The accuracy of the method was assessed by analysis of 30 wine samples by the proposed methodology and manual procedures. There were no statistical differences between the 2 sets of results, in both determinations. Relative standard deviations lower than 2.1 and 2.4% were attained by the spectrophotometric and potentiometric measurements, respectively. A determination rate of 52h(-1) was achieved.

  14. Role of hemolysis in potassium release by iodinated contrast medium

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, K.; Nakamura, T.; Shimizu, Y. [Department of Radiology, Kyoto City Hospital (Japan)

    1999-09-01

    It has been demonstrated that an iodinated contrast medium (CM) causes release of potassium into blood vessel lumina, resulting in an increase in serum potassium. The purpose of the present study was to assess whether this potassium release is due to hemolysis. Fresh human blood was mixed in vitro with CM at a ratio of 10:2. Potassium release rates were determined, and serum haptoglobin and free hemoglobin were measured after 30 min of exposure to CM. To compare the potassium release curve between CM exposure and true hemolysis induced by distilled water, fresh human blood was also mixed with distilled water. The level of serum haptoglobin decreased due to hemodilution. Changes in haptoglobin were not correlated with potassium release rates. The serum free hemoglobin level did not increase significantly, and there was no correlation between changes in the free hemoglobin level and the rate of potassium release. Hemolysis caused by water occurred instantaneously, whereas potassium release caused by CM was a slow response, which was linearly correlated with exposure time. Potassium release from blood cannot be explained by hemolysis. (orig.) With 4 figs., 4 tabs., 3 refs.

  15. The use and development of ion dispensers for laser-cooled atomic ion experiments

    Science.gov (United States)

    Hucul, David; Christensen, Justin E.; Hudson, Eric R.; Campbell, Wesley C.

    2017-04-01

    Fast, reliable, efficient loading of ions in ion traps is important for laser cooled ion trapping experiments. We utilize a simple surface ionization technique where ions are directly emitted from a platinum surface upon sublimation. This technique of direct ion production has wide applicability to ion trapping experiments and should apply to the direct production of positively charged atomic and molecular species as well as molecular anions. We experimentally demonstrate the ease and flexibility of this technique by directly producing calcium, strontium, cesium, barium, and potassium ions from a heated platinum surface. In addition, this technique is useful for loading rare isotopes into an ion trap. We experimentally demonstrate this by loading large numbers barium ions into an ion trap and distilling rare, isotopically pure ion chains through voltage control and laser heating and cooling. These techniques are directly applicable to the loading of 133Ba+ ions, a candidate qubit that combines the favorable atomic structure of 171Yb+, long-lived metastable states to ensure high fidelity detection, and visible optical transitions to leverage existing optical technologies.

  16. Electrochemical evidences and consequences of significant differences in ions diffusion rate in polyacrylate-based ion-selective membranes.

    Science.gov (United States)

    Woźnica, Emilia; Mieczkowski, Józef; Michalska, Agata

    2011-11-21

    The origin and effect of surface accumulation of primary ions within the ion-selective poly(n-butyl acrylate)-based membrane, obtained by thermal polymerization, is discussed. Using a new method, based on the relation between the shape of a potentiometric plot and preconditioning time, the diffusion of copper ions in the membrane was found to be slow (the diffusion coefficient estimated to be close to 10(-11) cm(2) s(-1)), especially when compared to ion-exchanger counter ions--sodium cations diffusion (a diffusion coefficient above 10(-9) cm(2) s(-1)). The higher mobility of sodium ions than those of the copper-ionophore complex results in exposed ion-exchanger role leading to undesirably exposed sensitivity to sodium or potassium ions.

  17. Potassium Iodide ("KI"): Instructions to Make Potassium Iodide Solution for Use During a Nuclear Emergency (Liquid Form)

    Science.gov (United States)

    ... Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products ... it Email Print Instructions to Make Potassium Iodide Solution for Use During a Nuclear ...

  18. Dialysate Potassium, Serum Potassium, Mortality, and Arrhythmia Events in Hemodialysis: Results From the Dialysis Outcomes and Practice Patterns Study (DOPPS).

    Science.gov (United States)

    Karaboyas, Angelo; Zee, Jarcy; Brunelli, Steven M; Usvyat, Len A; Weiner, Daniel E; Maddux, Franklin W; Nissenson, Allen R; Jadoul, Michel; Locatelli, Francesco; Winkelmayer, Wolfgang C; Port, Friedrich K; Robinson, Bruce M; Tentori, Francesca

    2017-02-01

    Sudden death is a leading cause of death in patients on maintenance hemodialysis therapy. During hemodialysis sessions, the gradient between serum and dialysate levels results in rapid electrolyte shifts, which may contribute to arrhythmias and sudden death. Controversies exist about the optimal electrolyte concentration in the dialysate; specifically, it is unclear whether patient outcomes differ among those treated with a dialysate potassium concentration of 3 mEq/L compared to 2 mEq/L. Prospective cohort study. 55,183 patients from 20 countries in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 1 to 5 (1996-2015). Dialysate potassium concentration at study entry. Cox regression was used to estimate the association between dialysate potassium concentration and both all-cause mortality and an arrhythmia composite outcome (arrhythmia-related hospitalization or sudden death), adjusting for potential confounders. During a median follow-up of 16.5 months, 24% of patients died and 7% had an arrhythmia composite outcome. No meaningful difference in clinical outcomes was observed for patients treated with a dialysate potassium concentration of 3 versus 2 mEq/L (adjusted HRs were 0.96 [95% CI, 0.91-1.01] for mortality and 0.98 [95% CI, 0.88-1.08] for arrhythmia composite). Results were similar across predialysis serum potassium levels. As in prior studies, higher serum potassium level was associated with adverse outcomes. However, dialysate potassium concentration had only minimal impact on serum potassium level measured predialysis (+0.09 [95% CI, 0.05-0.14] mEq/L serum potassium per 1 mEq/L greater dialysate potassium concentration). Data were not available for delivered (vs prescribed) dialysate potassium concentration and postdialysis serum potassium level; possible unmeasured confounding. In combination, these results suggest that approaches other than altering dialysate potassium concentration (eg, education on dietary potassium sources and

  19. High-Resolution Spectroscopic Observations of Potassium Emissions in the Lunar Exosphere

    Science.gov (United States)

    Robertson, Sarena D.; Oliversen, Ronald J.; Mierkiewicz, Edwin J.; Kuruppuaratchi, Dona Chathuni P.; Derr, Nicholas James; Gallant, Margaret A.; McFarland, Christina G.; Sarantos, Menelaos

    2018-01-01

    We investigate lunar exospheric potassium D1 emissions (7698.9646 Å) using high-resolution (R = 180,000 or 1.7 km/s) spectroscopy with our dual-etalon Fabry-Perot instrument to measure line widths and radial velocities. The Field of View (FOV) is 2 arcmins (~224 km at the mean lunar distance of 384,400 km) positioned tangent to the sunlit limb. The FOV placements are at cardinal directions from a variety of reference craters. All observations are collected at the National Solar Observatory McMath-Pierce Telescope in Kitt Peak, Arizona. The data are from several observations from 2014 through 2017 at various times of the year. Results are produced via a newly created automated data reduction using Python. Python was chosen as an open-source alternative to the previously used IDL and MATLAB scripts to decrease the cost of software licenses and maintenance. The potassium spectral line profiles provide a direct method to track exospheric effective temperatures and velocities. By monitoring the state of the potassium emissions over different lunar phases, solar activity, and the influx of meteor streams, we can constrain physical processes of sources and sinks at the lunar surface. Mechanisms that create the exosphere include photon-stimulated desorption, thermal evaporation, meteoroid impact vaporization, and ion sputtering via solar wind. In contrast, the exosphere is diminished due to the low lunar escape velocity, solar radiation pressure, and neutral gas being ionized and swept away by the interplanetary and terrestrial magnetic field. Preliminary analysis of 2017 data (January through June, excluding February) indicates an average potassium temperature of 1140 K but varying over the range of 550 K to 2000 K. Preliminary results from 2014 data depict a similar range of temperatures to that of 2017. Further analysis is expected for additional data from 2014 to later observations in 2017 that were not included in the initial set of models.

  20. Expression and purification of native and functional influenza A virus matrix 2 proton selective ion channel.

    Science.gov (United States)

    Desuzinges Mandon, Elodie; Traversier, Aurélien; Champagne, Anne; Benier, Lorraine; Audebert, Stéphane; Balme, Sébastien; Dejean, Emmanuel; Rosa Calatrava, Manuel; Jawhari, Anass

    2017-03-01

    Influenza A virus displays one of the highest infection rates of all human viruses and therefore represents a severe human health threat associated with an important economical challenge. Influenza matrix protein 2 (M2) is a membrane protein of the viral envelope that forms a proton selective ion channel. Here we report the expression and native isolation of full length active M2 without mutations or fusions. The ability of the influenza virus to efficiently infect MDCK cells was used to express native M2 protein. Using a Calixarene detergents/surfactants based approach; we were able to solubilize most of M2 from the plasma membrane and purify it. The tetrameric form of native M2 was maintained during the protein preparation. Mass spectrometry shows that M2 was phosphorylated in its cytoplasmic tail (serine 64) and newly identifies an acetylation of the highly conserved Lysine 60. ELISA shows that solubilized and purified M2 was specifically recognized by M2 antibody MAB65 and was able to displace the antibody from M2 MDCK membranes. Using a bilayer voltage clamp measurement assay, we demonstrate a pH dependent proton selective ion channel activity. The addition of the M2 ion channel blocker amantadine allows a total inhibition of the channel activity, illustrating therefore the specificity of purified M2 activity. Taken together, this work shows the production and isolation of a tetrameric and functional native M2 ion channel that will pave the way to structural and functional characterization of native M2, conformational antibody development, small molecules compounds screening towards vaccine treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. The Segregated Expression of Voltage-Gated Potassium and Sodium Channels in Neuronal Membranes: Functional Implications and Regulatory Mechanisms.

    Science.gov (United States)

    Duménieu, Maël; Oulé, Marie; Kreutz, Michael R; Lopez-Rojas, Jeffrey

    2017-01-01

    Neurons are highly polarized cells with apparent functional and morphological differences between dendrites and axon. A critical determinant for the molecular and functional identity of axonal and dendritic segments is the restricted expression of voltage-gated ion channels (VGCs). Several studies show an uneven distribution of ion channels and their differential regulation within dendrites and axons, which is a prerequisite for an appropriate integration of synaptic inputs and the generation of adequate action potential (AP) firing patterns. This review article will focus on the signaling pathways leading to segmented expression of voltage-gated potassium and sodium ion channels at the neuronal plasma membrane and the regulatory mechanisms ensuring segregated functions. We will also discuss the relevance of proper ion channel targeting for neuronal physiology and how alterations in polarized distribution contribute to neuronal pathology.

  2. Thanatochemistry: Study of vitreous humor potassium

    African Journals Online (AJOL)

    Nilesh Keshav Tumram

    2014-02-18

    Feb 18, 2014 ... glycolysis active membrane transport stops and the loss of selective membrane permeability and diffusion of ions and other parameters according to their concentration gradients starts. Furthermore, analytical concentrations are affected by postmortem changes like redistribution/hemoconcentration.

  3. Luminescent Properties of Cerium Doped Potassium Iodide Single Crystals in Response to γ-irradiation.

    Science.gov (United States)

    Bangaru, S; Saradha, K; Muralidharan, G

    2015-05-01

    Potassium iodide doped with cerium ions were prepared by Bridgemann Stockbarger technique and investigated by optical absorption, Photoluminescence(PL), Thermoluminescence(TL), Photostimulated Luminescence(PSL) and TL emission. The optical absorption measurement indicates that F and V centers are formed in the crystals during the γ-ray irradiation process. Optical absorption and Photoluminescence studies confirm the presence of cerium ions in the trivalent state. Spectral distribution under the Thermoluminescence Emission(TLE) and Optically Stimulated Luminescence(OSL) support the idea that the defect annihilation process to be due to thermal release of F-electron in KI:Ce(3+) crystals. Both Ce(3+) and Ce(2+) emissions were observed in the Thermoluminescence emission of the crystals. Thermoluminescence(TL) has been identified to be due to thermal release of electron produced during colouration process.

  4. Potassium Niobate Nanolamina: A Promising Adsorbent for Entrapment of Radioactive Cations from Water

    Science.gov (United States)

    Sun, Jin; Yang, Dongjiang; Sun, Cuihua; Liu, Long; Yang, Shuanglei; (Alec) Jia, Yi; Cai, Rongsheng; Yao, Xiangdong

    2014-12-01

    Processing and managing radioactive waste is a great challenge worldwide as it is extremely difficult and costly; the radioactive species, cations or anions, leaked into the environment are a serious threat to the health of present and future generations. We report layered potassium niobate (K4Nb6O17) nanolamina as adsorbent to remove toxic Sr2+, Ba2+ and Cs+ cations from wastewater. The results show that K4Nb6O17 nanolamina can permanently confine the toxic cations within the interlayer spacing via a considerable deformation of the metastable layered structure during the ion exchange process. At the same time, the nanolaminar adsorbent exhibits prompt adsorption kinetics, high adsorption capacity and selectivity, and superior acid resistance. These merits make it be a promising material as ion exchanger for the removal of radioactive cations from wastewater.

  5. Neurological disease mutations compromise a C-terminal ion pathway in the Na(+)/K(+)-ATPas

    DEFF Research Database (Denmark)

    Poulsen, Hanne; Khandelia, Himanshu; Morth, Jens Preben

    2010-01-01

    The Na(+)/K(+)-ATPase pumps three sodium ions out of and two potassium ions into the cell for each ATP molecule that is split, thereby generating the chemical and electrical gradients across the plasma membrane that are essential in, for example, signalling, secondary transport and volume regulat...

  6. Neurological disease mutations compromise a C-terminal ion pathway in the Na(+)/K(+)-ATPase

    DEFF Research Database (Denmark)

    Poulsen, Hanne; Khandelia, Himanshu; Morth, J Preben

    2010-01-01

    The Na(+)/K(+)-ATPase pumps three sodium ions out of and two potassium ions into the cell for each ATP molecule that is split, thereby generating the chemical and electrical gradients across the plasma membrane that are essential in, for example, signalling, secondary transport and volume regulat...

  7. Correlation of radiative properties of rare earth ions (Pr and Nd ) in ...

    Indian Academy of Sciences (India)

    Unknown

    elements, 'fcal' values are obtained. The experimental spectral intensities for all the transitions of Pr3+ and Nd3+ ions in 0⋅1 and 0⋅5 mol% concentrations of rare earth ion in potassium and lead chlorophosphate glasses are presented in table 3. The rms deviations which show agreement between experimental and ...

  8. Changes in erythrocyte contents of potassium, sodium and magnesium and Na, K-pump activity after the administration of potassium and magnesium salts.

    Science.gov (United States)

    Sriboonlue, Pote; Jaipakdee, Sudjai; Jirakulsomchok, Dusit; Mairiang, Eimorn; Tosukhowong, Piyaratana; Prasongwatana, Vitoon; Savok, Sompong

    2004-12-01

    Low potassium and magnesium status and decreased Na, K-pump activity is an endemic condition among rural Northeast Thais. The authors examined the effect of supplementing potassium and magnesium on erythrocyte potassium, sodium and magnesium content and on Na, K-pump activity. Rural Northeast Thai renal stone patients (62) were recruited, divided into four groups and supplemented for one month with potassium chloride (Group1, n = 16), potassium-sodium citrate (Group2, n = 15), chelated magnesium (Group 3, n =16) and potassium-magnesium citrate (Group 4, n =15) in order to achieve 40 mmol potassium, 10 mmol magnesium and 60 mmol citrate daily. After supplementation with potassium (Groups 1, 2 and 4), plasma potassium and Na, K-pump activity rose significantly in Groups 1, 2 and 4, but erythrocyte potassium rose only in Groups 2 and 4. When supplementing elemental magnesium (Groups 3 and 4), the chelated magnesium caused a significant increase in plasma potassium, erythrocyte potassium, sodium and magnesium without a significant increase in Na, K-pump activity. By contrast, potassium-magnesium citrate caused a significant increase in erythrocyte potassium and magnesium and Na, K-pump activity, but depressed erythrocyte sodium. These results suggest the forms of potassium and /or magnesium salts being supplemented should be considered because they affect erythrocyte potassium, sodium and magnesium content and Na, K-pump activity differently.

  9. Potassium cycling and losses in grassland systems : a review

    NARCIS (Netherlands)

    Kayser, M; Isselstein, J

    Cycling of potassium in grassland systems has received relatively little attention in research and practice in recent years. Balanced nutrient systems require consideration of nutrients other than nitrogen (N). Potassium (K) is needed in large amounts and is closely related to N nutrition. In

  10. A novel potassium deficiency-induced stimulon in Anabaena torulosa

    Indian Academy of Sciences (India)

    These proteins contrast with the dinitrogenase reductase of A. torulosa and the glycine betaine-binding protein of E. coli, both of which were osmo-induced to a higher level in potassium-supplemented conditions. The data demonstrate the occurrence of novel potassium deficiency-induced stimulons and a wider role of K+ in ...

  11. Sodium and potassium concentrations in floral nectars in relation to ...

    African Journals Online (AJOL)

    Sodium and potassium concentrations have been measured in nectar from a variety of flowering plants visited by honey bees (Apis mellifera capensis). In 18 plant species the mean sodium concentration was 9,8 ± 1,4 mmol (± S.E.), and the mean potassium concentration was 18,7 ± 4,3 mmol. These results are compared ...

  12. Sodium and potassium concentrations in floral nectars in relation to ...

    African Journals Online (AJOL)

    1989-08-03

    Aug 3, 1989 ... Sodium and potassium concentrations have been measured in nectar from a variety of flowering plants visited by honey bees fApis me/litera capensis). In 18 plant species the mean sodium concentration was 9,8 ± 1,4 mmol (± S.E.), and the mean potassium concentration was 18,7 ± 4,3 mmol.

  13. Potassium Concentration in Blood of Brazilian Athletes Using NAA

    Science.gov (United States)

    Kovacs, Luciana; Zamboni, Cibele B.; Lourenço, Thiago F.; Nunes, Lázaro A. S.; Macedo, Denise V.

    2011-08-01

    In this study the potassium levels in blood were determined in male athletes, age 18 to 26 years, before, during and after the tread mill exercise protocol using Neutron Activation Analyses (NAA). These data are important to check the potassium imbalance in blood during the period of competition preparation.

  14. Haemoglobin and potassium polymorphism in agro-pastoral goats ...

    African Journals Online (AJOL)

    The Chi-square test revealed that the population of goats in the study area was in Hardy- Weinberg equilibrium. The gene frequencies of potassium polymorphism were 0.844 and 0.156 for high (HK) and low potassium (LK) types, respectively. The genotypic frequencies were 0.91 for HK and 0.01 for LK in the overall ...

  15. Evaluation of in vitro antifungal activity of potassium bicarbonate on ...

    African Journals Online (AJOL)

    The effect of increased concentrations of potassium bicarbonate (KHCO3) as a possible alternative to synthetic fungicides for controlling Rhizoctonia solani AG 4 HG-I and Sclerotinia sclerotiorum was evaluated in vitro, in this study. In addition, the effect of potassium bicarbonate on Trichoderma sp., a natural antagonist on ...

  16. Relationship between serum total magnesium and serum potassium ...

    African Journals Online (AJOL)

    Introduction: Potassium and magnesium are the two most abundant intra cellular cations. They play pivotal roles in many essential biological processes. Deficiencies of these electrolytes are of clinical importance in hospitalised patients. Aim: To determine the relationship between serum total magnesium and potassium ...

  17. Potassium silicate-zinc oxide solution for metal finishes

    Science.gov (United States)

    Schutt, J. B.

    1970-01-01

    Examples of zinc dust formulations, which are not subject to cracking or crazing, are fire retardant, and have high adhesive qualities, are listed. The potassium silicate in these formulations has mol ratios of dissolved silica potassium oxide in the range 4.8 to 1 - 5.3 to 1.

  18. Potassium bromate content of some baked breads sold in Kano ...

    African Journals Online (AJOL)

    Background: Potassium bromate is an additive used by some bakers to make the bread rise rapidly, create a good texture in the finished product and to give bulkiness to the dough. Objective: The main objective of this work was to assess the potassium bromate residues of some baked breads sold in some selected local ...

  19. Determination and comparison of vitamin C, calcium and potassium ...

    African Journals Online (AJOL)

    Vitamin C content was determined by 2,6-dichloroindophenol titrimetric method while calcium and potassium were determined by atomic absorption spectroscopy. Results from the study showed inconsistent pattern with respect to vitamin C, calcium and potassium contents in the conventionally and organically grown ...

  20. 40 CFR 721.10021 - Magnesium potassium titanium oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Magnesium potassium titanium oxide... Specific Chemical Substances § 721.10021 Magnesium potassium titanium oxide. (a) Chemical substance and... titanium oxide (PMN P-01-764; CAS No. 39290-90-9) is subject to reporting under this section for the...

  1. Potassium Bromate Content of Bread Produced in Sokoto Metropolis ...

    African Journals Online (AJOL)

    Fifteen different bread samples were randomly collected from various local bakeries located in Sokoto metropolis. The samples were analysed for presence and quantity of potassium bromate. All the samples were analysed using the redox titrimetric method for the detection of potassium bromate. All the samples contained ...

  2. Accidental Potassium Bromate Poisoning Causing Acute Renal Failure

    OpenAIRE

    Adeleke SI; Asani MO

    2009-01-01

    Accidental poisoning is common in children. Potassium bromate is commonly used additive and raising agent in many edibles especially bread which is a staple food in Nigeria. This communication is that of an unusual case of acute renal failure following accidental ingestion of potassium bromate tablets.

  3. Top-dressing of Potassium Fertilizers on Safflower

    Directory of Open Access Journals (Sweden)

    Neginsadat Amir Khalili

    2016-10-01

    Full Text Available To determine the effects of potassium foliar application (with two levels, use and non-use from potassium sulphate source and top-dressing application of potassium fertilizer (with two levels, use and non-use from potassium chloride source on number of seeds per capitulum, number of side branch per plant, seed yield, seed oil content, oil yield, seed to coat ratio, plant height and shoot dry weight in three safflower, genotypes including KW.2, Padideh and Goldasht a factorial experiment based on the randomized complete block design (RCBD with three replications, was conducted during 2013 growing season at the Agricultural Research Center of Semnan province (Shahroud. Results showed that the highest average of number of seeds per capitulum (28.70, number of side branch per plant (17.83 and seed to coat ratio (1.47 were found in KW.2 genotype. The highest seed yield (2627.7 kg/ha and oil yield (1350.5 kg/ha were found from potassium sulphate foliar application in Padideh and KW.2 genotypes respectively. The interaction effect of genotype × potassium foliar application was significant for seed and oil yields. In conclusion, it was determined that potassium sulphate foliar application has better impacts on seed and oil yield of safflower genotypes than potassium top-dressing application.

  4. Accidental Potassium Bromate Poisoning Causing Acute Renal Failure

    Directory of Open Access Journals (Sweden)

    Adeleke SI

    2009-05-01

    Full Text Available Accidental poisoning is common in children. Potassium bromate is commonly used additive and raising agent in many edibles especially bread which is a staple food in Nigeria. This communication is that of an unusual case of acute renal failure following accidental ingestion of potassium bromate tablets

  5. Effects of Nitrogen, Potassium and Weed Interference on Yield of ...

    African Journals Online (AJOL)

    Parameters studied included bulb weight (g), bulb diameter (cm) and bulb heights (cm). The result indicated significant (P<0.05) effect of potassium, nitrogen and weed interference on the yield of onion. Highest bulb yield was obtained with 250 kg/ha potassium, 150 kg/ha nitrogen and the 4 WAT weeding regime. No bulbs ...

  6. The Effect Of Potassium Bromate On Some Haematological ...

    African Journals Online (AJOL)

    Summary: Potassium bromate used widely in foods has been associated with various complications in humans. However there is paucity of literature on adverse effects on haematological parameters. Thus we decided to carry out an experimental study to determine the effects of potassium bromate on some blood indices ...

  7. Extractability of Potassium from Some Organic Manures in Aqueous ...

    African Journals Online (AJOL)

    The effect of pH, time and concentration on the extractability of potassium from five types of organic manures (cow dung, local chickens, duck and commercial chickens, faeces on bedded and unbedded floor) were studied. Experiments were conducted in water at 40oC. Cumulative extraction curves of potassium resulting ...

  8. Acute toxicity studies of potassium permanganate in Swiss albino mice

    African Journals Online (AJOL)

    Acute toxicity study of potassium permanganate was carried out in Swiss albino mice. Potassium permanganate was administered at dose rate of 0.0, 500, 1000, 1500, 2000, 2500, 3000 and 3500mg/kg body weight to groups 1, 2, 3, 4, 5, 6, 7 and 8, ten per group for LD50 determination. The dead animals were posted for ...

  9. Ion channelopathies and migraine pathogenesis.

    Science.gov (United States)

    Albury, Cassie L; Stuart, Shani; Haupt, Larisa M; Griffiths, Lyn R

    2017-08-01

    Migraine is a common neurological disorder that affects approximately 12-20% of the general adult population. Migraine pathogenesis is complex and not wholly understood. Molecular genetic investigations, imaging and biochemical studies, have unveiled a number of interconnected neurological pathways which seem to have a cause and effect component integral to its cause. Much weight of migraine attack initiation can be placed on the initial trigger and the pathways involved in its neuronal counter reaction. Ion channels play a large role in the generation, portrayal and mitigation of the brains response to external triggers. Several genetic studies have identified and implicated a number of ion channelopathy genes which may contribute to this generalised process. This review will focus on the genetics of migraine with particular emphasis placed on the potentially important role genes HEPH (responsible for iron transport and homeostasis) and KCNK18 (important for the transport and homeostasis of potassium) play in migraine cause.

  10. Structures of Pseudomonas aeruginosa β-ketoacyl-(acyl-carrier-protein) synthase II (FabF) and a C164Q mutant provide templates for antibacterial drug discovery and identify a buried potassium ion and a ligand-binding site that is an artefact of the crystal form

    Energy Technology Data Exchange (ETDEWEB)

    Baum, Bernhard [Johannes Gutenberg-Universität, Staudinger Weg 5, 55128 Mainz (Germany); Lecker, Laura S. M.; Zoltner, Martin [University of Dundee, Dundee DD1 4EH, Scotland (United Kingdom); Jaenicke, Elmar [Johannes Gutenberg-Universität, Jakob Welder Weg 26, 55128 Mainz (Germany); Schnell, Robert [Karolinska Institutet, 17 177 Stockholm (Sweden); Hunter, William N., E-mail: w.n.hunter@dundee.ac.uk [University of Dundee, Dundee DD1 4EH, Scotland (United Kingdom); Brenk, Ruth, E-mail: w.n.hunter@dundee.ac.uk [Johannes Gutenberg-Universität, Staudinger Weg 5, 55128 Mainz (Germany)

    2015-07-28

    Three crystal structures of recombinant P. aeruginosa FabF are reported: the apoenzyme, an active-site mutant and a complex with a fragment of a natural product inhibitor. The characterization provides reagents and new information to support antibacterial drug discovery. Bacterial infections remain a serious health concern, in particular causing life-threatening infections of hospitalized and immunocompromised patients. The situation is exacerbated by the rise in antibacterial drug resistance, and new treatments are urgently sought. In this endeavour, accurate structures of molecular targets can support early-stage drug discovery. Here, crystal structures, in three distinct forms, of recombinant Pseudomonas aeruginosa β-ketoacyl-(acyl-carrier-protein) synthase II (FabF) are presented. This enzyme, which is involved in fatty-acid biosynthesis, has been validated by genetic and chemical means as an antibiotic target in Gram-positive bacteria and represents a potential target in Gram-negative bacteria. The structures of apo FabF, of a C164Q mutant in which the binding site is altered to resemble the substrate-bound state and of a complex with 3-(benzoylamino)-2-hydroxybenzoic acid are reported. This compound mimics aspects of a known natural product inhibitor, platensimycin, and surprisingly was observed binding outside the active site, interacting with a symmetry-related molecule. An unusual feature is a completely buried potassium-binding site that was identified in all three structures. Comparisons suggest that this may represent a conserved structural feature of FabF relevant to fold stability. The new structures provide templates for structure-based ligand design and, together with the protocols and reagents, may underpin a target-based drug-discovery project for urgently needed antibacterials.

  11. Nitric oxide regulates neuronal activity via calcium-activated potassium channels.

    Directory of Open Access Journals (Sweden)

    Lei Ray Zhong

    Full Text Available Nitric oxide (NO is an unconventional membrane-permeable messenger molecule that has been shown to play various roles in the nervous system. How NO modulates ion channels to affect neuronal functions is not well understood. In gastropods, NO has been implicated in regulating the feeding motor program. The buccal motoneuron, B19, of the freshwater pond snail Helisoma trivolvis is active during the hyper-retraction phase of the feeding motor program and is located in the vicinity of NO-producing neurons in the buccal ganglion. Here, we asked whether B19 neurons might serve as direct targets of NO signaling. Previous work established NO as a key regulator of growth cone motility and neuronal excitability in another buccal neuron involved in feeding, the B5 neuron. This raised the question whether NO might modulate the electrical activity and neuronal excitability of B19 neurons as well, and if so whether NO acted on the same or a different set of ion channels in both neurons. To study specific responses of NO on B19 neurons and to eliminate indirect effects contributed by other cells, the majority of experiments were performed on single cultured B19 neurons. Addition of NO donors caused a prolonged depolarization of the membrane potential and an increase in neuronal excitability. The effects of NO could mainly be attributed to the inhibition of two types of calcium-activated potassium channels, apamin-sensitive and iberiotoxin-sensitive potassium channels. NO was found to also cause a depolarization in B19 neurons in situ, but only after NO synthase activity in buccal ganglia had been blocked. The results suggest that NO acts as a critical modulator of neuronal excitability in B19 neurons, and that calcium-activated potassium channels may serve as a common target of NO in neurons.

  12. Effect of Patiromer on Urinary Ion Excretion in Healthy Adults

    Science.gov (United States)

    Spiegel, David M.; Gross, Coleman; Benton, Wade W.; Fogli, Jeanene; Hill Gallant, Kathleen M.; Du Mond, Charles; Block, Geoffrey A.; Weir, Matthew R.; Pitt, Bertram

    2016-01-01

    Background and objectives Patiromer is a nonabsorbed potassium-binding polymer that uses calcium as the counterexchange ion. The calcium released with potassium binding has the potential to be absorbed or bind phosphate. Because binding is not specific for potassium, patiromer can bind other cations. Here, we evaluate the effect of patiromer on urine ion excretion in healthy adults, which reflects gastrointestinal ion absorption. Design, setting, participants, & measurements We analyzed the effect of patiromer on urine potassium, sodium, magnesium, calcium, and phosphate in two studies. Healthy adults on controlled diets in a clinical research unit were given patiromer up to 50.4 g/d divided three times a day for 8 days (dose-finding study) or 25.2 g/d in a crossover design as daily or divided (two or three times a day) doses for 18 days (dosing regimen study). On the basis of 24-hour collections, urinary ion excretion during the baseline period (days 5–11) was compared with that during the treatment period (days 13–19; dose-finding study), and the last 4 days of each period were compared across regimens (dosing regimen study). Results In the dose-finding study, patiromer induced a dose-dependent decrease in urine potassium, urine magnesium, and urine sodium (P<0.01 for each). Patiromer at 25.2 g/d decreased urine potassium (mean±SD) by 1140±316 mg/d, urine magnesium by 45±1 mg/d, and urine sodium by 225±145 mg/d. Urine calcium increased in a dose-dependent manner, and urine phosphate decreased in parallel (both P<0.01). Patiromer at 25.2 g/d increased urine calcium by 73±23 mg/d and decreased urine phosphate by 64±40 mg/d. Urine potassium, urine sodium, and urine magnesium were unaffected by dosing regimen, whereas the increase in urine calcium was significantly lower with daily compared with three times a day dosing (P=0.01). Urine phosphate also decreased less with daily compared with two or three times a day dosing (P<0.05). Conclusions In healthy

  13. 75 FR 76016 - Determination That AUGMENTIN `125' (Amoxicillin; Clavulanate Potassium) Chewable Tablet and Six...

    Science.gov (United States)

    2010-12-07

    ... HUMAN SERVICES Food and Drug Administration Determination That AUGMENTIN `125' (Amoxicillin; Clavulanate Potassium) Chewable Tablet and Six Other AUGMENTIN (Amoxicillin; Clavulanate Potassium) Drug Products Were... (amoxicillin; clavulanate potassium) drug products listed in this notice were not withdrawn from sale for...

  14. Metal ions and human sperm mannose receptors.

    Science.gov (United States)

    Benoff, S; Cooper, G W; Centola, G M; Jacob, A; Hershlag, A; Hurley, I R

    2000-09-01

    Zinc and lead concentrations were measured in seminal plasma from fertile donors, infertile men with varicocoele and men undergoing work-ups for in vitro fertilization. Ejaculated spermatozoa from these subjects were incubated in vitro with various metal ions and/or dibromoethane and dibromochloropropane. Mannose receptor expression was correlated with metal and toxicant levels. Sperm distributions of potassium channels were compared with lead ions and calcium channels with zinc ions. Mannose receptor expression by capacitated spermatozoa increased linearly with seminal plasma zinc levels, and correlated inversely with lead levels. Cobalt had no effect on mannose receptor expression, but nickel had a concentration-dependent biphasic effect. Mannose receptor expression was not affected by dibromoethane and dibromochloropropane if the cholesterol content of the sperm membrane was high, but mannose receptor expression was decreased in low cholesterol spermatozoa by exposures below estimated permissive exposure limits. Potassium channels and lead ions co-localized over the entire head of human spermatozoa, while both calcium channels and zinc ions were confined to the equatorial segment of the head. Mannose receptor expression on the external surface of the human sperm plasma membrane is a biomarker for the effects of transition and heavy metals and organic toxicants on sperm fertility potential.

  15. Potassium bromide, KBr/ ε: New Force Field

    Science.gov (United States)

    Fuentes-Azcatl, Raúl; Barbosa, Marcia C.

    2018-02-01

    We propose a new force field for the Potassium Bromide, the KBr/ ε. The crystal density and structure, as well as, the density, the viscosity and the dielectric constant of the solution in water were computed and compared with the experiments and other atomistic models. Next, the transferability of the KBr/ ε and of the NaCl/ ε models is verified by creating the KCl/ ε and the NaBr/ ε models. The strategy was to employ the same parameters obtained for the NaCl/ ε and for the KBr/ ε force fields for the building up of the KCl/ ε and the NaBr/ ε models . The thermodynamic and dynamic properties of these two new models were compared with the experimental

  16. Potassium Capture by Kaolin, Part 1: KOH

    DEFF Research Database (Denmark)

    Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao

    2018-01-01

    The reaction of gaseous KOH with kaolin and mullite powder under suspension-fired conditions was studied by entrained flow reactor (EFR) experiments. A water-based slurry containing kaolin/mullite and KOH was fed into the reactor and the reacted solid samples were analyzed to quantify the K.......47 μm) and fine(D50 = 3.51 μm) kaolin powder at1100 and 1300 °C. The difference was less significant at 900°C. Mullite generated from kaolin captured KOH less effectively than kaolin at temperatures below 1100 °C. However, at 1300 and1450 °C, the amount of potassium captured by mullite became comparable...

  17. Paper-based potentiometric ion sensing.

    Science.gov (United States)

    Lan, Wen-Jie; Zou, Xu U; Hamedi, Mahiar M; Hu, Jinbo; Parolo, Claudio; Maxwell, E Jane; Bühlmann, Philippe; Whitesides, George M

    2014-10-07

    This paper describes the design and fabrication of ion-sensing electrochemical paper-based analytical devices (EPADs) in which a miniaturized paper reference electrode is integrated with a small ion-selective paper electrode (ISPE) for potentiometric measurements. Ion-sensing EPADs use printed wax barriers to define electrochemical sample and reference zones. Single-layer EPADs for sensing of chloride ions include wax-defined sample and reference zones that each incorporate a Ag/AgCl electrode. In EPADs developed for other electrolytes (potassium, sodium, and calcium ions), a PVC-based ion-selective membrane is added to separate the sample zone from a paper indicator electrode. After the addition of a small volume (less than 10 μL) of sample and reference solutions to different zones, ion-sensing EPADs exhibit a linear response, over 3 orders of magnitude, in ranges of electrolyte concentrations that are relevant to a variety of applications, with a slope close to the theoretical value (59.2/z mV). Ion-selective EPADs provide a portable, inexpensive, and disposable way of measuring concentrations of electrolyte ions in aqueous solutions.

  18. Ionic channels in plants: potassium transport Canais iônicos em plantas: o transporte de potássio

    Directory of Open Access Journals (Sweden)

    Antonio Costa de Oliveira

    1995-01-01

    Full Text Available The discovery of potassium channels on the plasma membrane has helped to elucidate important mechanisms in animal and plant physiology. Plant growth and development associated mechanisms, such as germination, leaf movements, stomatal action, ion uptake in roots, phloem transport and nutrient storage are linked to potassium transport. Studies describing potassium transport regulation by abscisic acid (ABA, Ca++, light and other factors are presented here. Also the types of channels that regulate potassium uptake and efflux in the cell, and the interaction of these channels with external signals, are discussed.A descoberta de canais iônicos presentes na membrana plasmática tem ajudado a elucidar importantes mecanismos fisiológicos em animais e plantas. Mecanismos associados ao crescimento e desenvolvimento das plantas, tais como germinação, movimento foliar, abertura e fechamento de estômatos, absorção de íons pelas raízes e armazenamento de nutrientes estão ligados ao transporte de potássio. Estudos descrevendo a regulação do transporte deste nutriente por ácido abscísico (ABA, Ca++, luz e outros fatores são apresentados. Os tipos de canais que regulam a saída e entrada de potássio na célula, e as interações destes com os sinais externos, são discutidos.

  19. Action of tributyltin (TBT) on the lipid content and potassium retention in the organotins degradating fungus Cunninghamella elegans.

    Science.gov (United States)

    Bernat, Przemysław; Słaba, Mirosława; Długoński, Jerzy

    2009-09-01

    The purpose of the presented paper was to study the effect of high concentrations of tributyltin (TBT) on the potassium retention and fatty acid (FA) composition of the fungus Cunninghamella elegans recognized as a very efficient TBT degrader. An increase in TBT had a strong influence on the potassium concentration in the fungus. In growth medium without TBT, the potassium content of the fungal cells was 5.8 mg K(+) g dry weight(-1). The maximum concentration of K(+) was 15.06 mg g(-1) dry weight at 30 mg l(-1) of TBT. The major FAs that characterized the tested strain were C16:0, C18:1, C18:2, C18:3 and C18:0. TBT in the concentration range 5-30 mg l(-1) strongly influenced the FA composition. In the presence of the organotin, the degree of saturation increased. It suggests that the observed changes promote an increase in the lipid ordering of the membrane by reducing its permeability and inhibiting potassium ion efflux.

  20. Reaction Mechanisms of Magnesium Potassium Phosphate Cement and its Application

    Science.gov (United States)

    Qiao, Fei

    Magnesium potassium phosphate cement (MKPC) is a kind of cementitious binder in which the chemical bond is formed via a heterogeneous acid-base reaction between dead burned magnesia powder and potassium phosphate solution at room temperature. Small amount of boron compounds can be incorporated in the cement as a setting retarder. The final reaction product of MgO-KH2PO4-H 2O ternary system is identified as magnesium potassium phosphate hexahydrate, MgKPO4·6H2O. However, the mechanisms and procedures through which this crystalline product is formed and the conditions under which the crystallization process would be influenced are not yet clear. Understanding of the reaction mechanism of the system is helpful for developing new methodologies to control the rapid reaction process and furthermore, to adjust the phase assemblage of the binder, and to enhance the macroscopic properties. This study is mainly focused on the examination of the reaction mechanism of MKPC. In addition, the formulation optimization, microstructure characterization and field application in rapid repair are also systematically studied. The chemical reactions between magnesia and potassium dihydrogen phosphate are essentially an acid-base reaction with strong heat release, the pH and temperature variation throughout the reaction process could provide useful information to disclose the different stages in the reaction. However, it would be very difficult to conduct such tests on the cement paste due to the limited water content and fast setting. In the current research, the reaction mechanism of MKPC is investigated on the diluted MKPC system through monitoring the pH and temperature development, identification of the solid phase formed, and measurement of the ionic concentration of the solution. The reaction process can be explained as follows: when magnesia and potassium phosphate powder are mixed with water, phosphate is readily dissolved, which is instantly followed by the dissociation of

  1. Effects of potassium peroxydiphosphate on bone resorption.

    Science.gov (United States)

    Gaffar, A; Alander, C B; Raisz, L G

    1991-10-01

    Potassium peroxydiphosphate (KPDP) is a slowly hydrolyzed pyrophosphate analog that can release hydrogen peroxide during hydrolysis. We tested its effects on the resorption of cultured fetal rat long bones as measured by the release of previously incorporated 45Ca, both by direct addition of KPDP to the medium and after preincubation of KPDP with large-molecular-weight resorbing factors followed by dialysis to reduce the KPDP concentration. With direct addition, KPDP at a concentration of 1 mM could inhibit the resortive response to bacterial lipopolysaccharide (LPS), parathyroid hormone (PTH), prostaglandin E2 (PGE2), and mouse recombinant interleukin-1 (mrIL-1). The response to LPS was partially inhibited at 0.3 mM KPDP. Control resorption in the absence of stimulators was also inhibited. Potassium pyrophosphate at 1 mM was less effective as an inhibitor of bone resorption. The inhibitory effects of KPDP did not appear to be due entirely to nonspecific toxicity since partial recovery occurred after it was removed. There was no significant decrease in [3H]thymidine or [3H]proline incorporation into bones incubated with KPDP at 1 mM for 5 days, but [3H]proline incorporation was decreased at 24 h, suggesting that KPDP may have a general inhibitory effect on bone cells. When media with and without stimulators of resorption were incubated overnight at 4 degrees C with KPDP at 5.8 mM and then dialyzed to bring the concentration to below 0.3 mM, the bone-resorbing activity of PTH, LPS, and mrIL-1 was completely lost. This may have been due to the slow release of hydrogen peroxide; however, preincubation with equimolar concentrations of H2O3 caused only partial inactivation of PTH and LPS. LPS.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Amiodarone Inhibits Apamin-Sensitive Potassium Currents

    Science.gov (United States)

    Turker, Isik; Yu, Chih-Chieh; Chang, Po-Cheng; Chen, Zhenhui; Sohma, Yoshiro; Lin, Shien-Fong; Chen, Peng-Sheng; Ai, Tomohiko

    2013-01-01

    Background Apamin sensitive potassium current (IKAS), carried by the type 2 small conductance Ca2+-activated potassium (SK2) channels, plays an important role in post-shock action potential duration (APD) shortening and recurrent spontaneous ventricular fibrillation (VF) in failing ventricles. Objective To test the hypothesis that amiodarone inhibits IKAS in human embryonic kidney 293 (HEK-293) cells. Methods We used the patch-clamp technique to study IKAS in HEK-293 cells transiently expressing human SK2 before and after amiodarone administration. Results Amiodarone inhibited IKAS in a dose-dependent manner (IC50, 2.67±0.25 µM with 1 µM intrapipette Ca2+). Maximal inhibition was observed with 50 µM amiodarone which inhibited 85.6±3.1% of IKAS induced with 1 µM intrapipette Ca2+ (n = 3). IKAS inhibition by amiodarone was not voltage-dependent, but was Ca2+-dependent: 30 µM amiodarone inhibited 81.5±1.9% of IKAS induced with 1 µM Ca2+ (n = 4), and 16.4±4.9% with 250 nM Ca2+ (n = 5). Desethylamiodarone, a major metabolite of amiodarone, also exerts voltage-independent but Ca2+ dependent inhibition of IKAS. Conclusion Both amiodarone and desethylamiodarone inhibit IKAS at therapeutic concentrations. The inhibition is independent of time and voltage, but is dependent on the intracellular Ca2+ concentration. SK2 current inhibition may in part underlie amiodarone's effects in preventing electrical storm in failing ventricles. PMID:23922993

  3. Amiodarone inhibits apamin-sensitive potassium currents.

    Directory of Open Access Journals (Sweden)

    Isik Turker

    Full Text Available Apamin sensitive potassium current (I KAS, carried by the type 2 small conductance Ca(2+-activated potassium (SK2 channels, plays an important role in post-shock action potential duration (APD shortening and recurrent spontaneous ventricular fibrillation (VF in failing ventricles.To test the hypothesis that amiodarone inhibits I KAS in human embryonic kidney 293 (HEK-293 cells.We used the patch-clamp technique to study I KAS in HEK-293 cells transiently expressing human SK2 before and after amiodarone administration.Amiodarone inhibited IKAS in a dose-dependent manner (IC50, 2.67 ± 0.25 µM with 1 µM intrapipette Ca(2+. Maximal inhibition was observed with 50 µM amiodarone which inhibited 85.6 ± 3.1% of IKAS induced with 1 µM intrapipette Ca(2+ (n = 3. IKAS inhibition by amiodarone was not voltage-dependent, but was Ca(2+-dependent: 30 µM amiodarone inhibited 81.5±1.9% of I KAS induced with 1 µM Ca(2+ (n = 4, and 16.4±4.9% with 250 nM Ca(2+ (n = 5. Desethylamiodarone, a major metabolite of amiodarone, also exerts voltage-independent but Ca(2+ dependent inhibition of I KAS.Both amiodarone and desethylamiodarone inhibit I KAS at therapeutic concentrations. The inhibition is independent of time and voltage, but is dependent on the intracellular Ca(2+ concentration. SK2 current inhibition may in part underlie amiodarone's effects in preventing electrical storm in failing ventricles.

  4. Ion regulatory function of the human kidney in prolonged space flights

    Science.gov (United States)

    Grigoriev, A. I.

    Ten cosmonauts, who performed 30-175-day space flights aboard Salyut-4 and Salyut-6, and over 60 test subjects who were exposed to bed rest of up to 182 days and immersion of up to 56 days, were examined. The renal excretion of potassium and calcium increased, reaching a maximum by the 4-6th weeks in prolonged space flights and simulation studies. During the load tests with potassium and calcium salt, excretion postflight was much higher than preflight. During potassium chloride load tests a positive correlation between the blood content of aldosterone and potassium excretion existed, whereas during calcium lactate load tests an increased calcium excretion was accompanied by a decrease in blood parathyroid hormone concentration. The most probable cause of the negative ion balance in weightlessness is the reduced capacity of tissues to retain electrolytes due to the decreased ion pool capacity. Different exercises have been shown to exert a beneficial effect on electrolyte metabolism.

  5. Voltage-dependent gating of hERG potassium channels

    Directory of Open Access Journals (Sweden)

    Yen May eCheng

    2012-05-01

    Full Text Available The mechanisms by which voltage-gated channels sense changes in membrane voltage and energetically couple this with opening of the ion conducting pore has been the source of significant interest. In voltage-gated potassium (Kv channels, much of our knowledge in this area comes from Shaker-type channels, for which voltage-dependent gating is quite rapid. In these channels, activation and deactivation are associated with rapid reconfiguration of the voltage-sensing domain unit that is electromechanically coupled, via the S4-S5 linker helix, to the rate-limiting opening of an intracellular pore gate. However, fast voltage-dependent gating kinetics are not typical of all Kv channels, such as Kv11.1 (human ether-a-go-go related gene, hERG, which activates and deactivates very slowly. Compared to Shaker channels, our understanding of the mechanisms underlying slow hERG gating is much poorer. Here, we present a comparative review of the structure-function relationships underlying voltage-dependent gating in Shaker and hERG channels, with a focus on the roles of the voltage sensing domain and the S4-S5 linker that couples voltage sensor movements to the pore. Measurements of gating current kinetics and fluorimetric analysis of voltage sensor movement are consistent with models suggesting that the hERG activation pathway contains a voltage independent step, which limits voltage sensor transitions. Constraints upon hERG voltage sensor movement may result from loose packing of the S4 helices and additional intra-voltage sensor counter charge interactions. More recent data suggest that key amino acid differences in the hERG voltage sensing unit and S4-S5 linker, relative to fast activating Shaker-type Kv channels, may also contribute to the increased stability of the resting state of the voltage sensor.

  6. Voltage-Dependent Gating of hERG Potassium Channels

    Science.gov (United States)

    Cheng, Yen May; Claydon, Tom W.

    2012-01-01

    The mechanisms by which voltage-gated channels sense changes in membrane voltage and energetically couple this with opening of the ion conducting pore has been the source of significant interest. In voltage-gated potassium (Kv) channels, much of our knowledge in this area comes from Shaker-type channels, for which voltage-dependent gating is quite rapid. In these channels, activation and deactivation are associated with rapid reconfiguration of the voltage-sensing domain unit that is electromechanically coupled, via the S4–S5 linker helix, to the rate-limiting opening of an intracellular pore gate. However, fast voltage-dependent gating kinetics are not typical of all Kv channels, such as Kv11.1 (human ether-à-go-go related gene, hERG), which activates and deactivates very slowly. Compared to Shaker channels, our understanding of the mechanisms underlying slow hERG gating is much poorer. Here, we present a comparative review of the structure–function relationships underlying activation and deactivation gating in Shaker and hERG channels, with a focus on the roles of the voltage-sensing domain and the S4–S5 linker that couples voltage sensor movements to the pore. Measurements of gating current kinetics and fluorimetric analysis of voltage sensor movement are consistent with models suggesting that the hERG activation pathway contains a voltage independent step, which limits voltage sensor transitions. Constraints upon hERG voltage sensor movement may result from loose packing of the S4 helices and additional intra-voltage sensor counter-charge interactions. More recent data suggest that key amino acid differences in the hERG voltage-sensing unit and S4–S5 linker, relative to fast activating Shaker-type Kv channels, may also contribute to the increased stability of the resting state of the voltage sensor. PMID:22586397

  7. Changes in potassium pools in Paraná soils under successive cropping and potassium fertilization

    Directory of Open Access Journals (Sweden)

    Fabio Steiner

    2015-12-01

    Full Text Available The changes in soil potassium pools under intense cropping and fertilized with potash fertilizer are still little known to the soils of Paraná State. The effects of potassium fertilization and successive cropping on changes in K pools in different soils of Paraná, Brazil, were investigated in this study. Twelve soil samples, collected from the upper layer 0–0.20 m, were fertilized or not with K and subjected to six successive cropping (i.e., soybean, pearl millet, wheat, common beans, soybean and maize. All the crops were grown for 45 days, and at the end of the second, fourth and sixth cropping, the soil from each pot was sampled to determination of the total K, non-exchangeable K, exchangeable K and solution K. The result showed that the soil potassium pools varied widely. Total K concentration ranged from 547 to 15,563 mg kg–1 (4,714 mg kg–1, on average. On the average, structural K, non-exchangeable K, exchangeable K and solution K of the soils constituted 84.0, 11.3, 4.6 and 0.1% of the total K, respectively. Soils differ in the ability to supply potassium to the plants in the short to medium term, due to the wide range of parent material and the degree of soil weathering. When the soils were not fertilized with K, the successive cropping of plants resulted in a continuous process of depletion of non-exchangeable K and exchangeable K pools; however, this depletion was less pronounced in soils with higher potential buffer capacity of K. The concentrations of K non-exchangeable and exchangeable K were increased with the addition of potassium fertilizers, indicating the occurrence of K fixation in soil. After the second cropping, the soil exchangeable K levels remained constant with values of 141 and 36 mg kg–1, respectively, with and without the addition of K fertilizer, reflecting in establishing of a new dynamic equilibrium of K in the soil.

  8. Transcriptome analysis of rice root responses to potassium deficiency

    Directory of Open Access Journals (Sweden)

    Ma Tian-Li

    2012-09-01

    Full Text Available Abstract Background Potassium (K+ is an important nutrient ion in plant cells and plays crucial roles in many plant physiological and developmental processes. In the natural environment, K+ deficiency is a common abiotic stress that inhibits plant growth and reduces crop productivity. Several microarray studies have been conducted on genome-wide gene expression profiles of rice during its responses to various stresses. However, little is known about the transcriptional changes in rice genes under low-K+ conditions. Results We analyzed the transcriptomic profiles of rice roots in response to low-K+ stress. The roots of rice seedlings with or without low-K+ treatment were harvested after 6 h, and 3 and 5 d, and used for microarray analysis. The microarray data showed that many genes (2,896 were up-regulated or down-regulated more than 1.2-fold during low-K+ treatment. GO analysis indicated that the genes showing transcriptional changes were mainly in the following categories: metabolic process, membrane, cation binding, kinase activity, transport, and so on. We conducted a comparative analysis of transcriptomic changes between Arabidopsis and rice under low-K+ stress. Generally, the genes showing changes in transcription in rice and Arabidopsis in response to low-K+ stress displayed similar GO distribution patterns. However, there were more genes related to stress responses and development in Arabidopsis than in rice. Many auxin-related genes responded to K+ deficiency in rice, whereas jasmonic acid-related enzymes may play more important roles in K+ nutrient signaling in Arabidopsis. Conclusions According to the microarray data, fewer rice genes showed transcriptional changes in response to K+ deficiency than to phosphorus (P or nitrogen (N deficiency. Thus, transcriptional regulation is probably more important in responses to low-P and -N stress than to low-K+ stress. However, many genes in some categories (protein kinase and ion transporter

  9. Potassium Silicate Foliar Fertilizer Grade from Geothermal Sludge and Pyrophyllite

    Directory of Open Access Journals (Sweden)

    Muljani Srie

    2016-01-01

    Full Text Available Potassium silicate fertilizer grade were successfully produced by direct fusion of silica (SiO2 and potasium (KOH and K2CO3 in furnaces at temperatures up to melting point of mixture. The geothermal sludge (98% SiO2 and the pyrophyllite (95% SiO2 were used as silica sources. The purposes of the study was to synthesise potassium silicate fertilizer grade having solids concentrations in the range of 31-37% K2O, and silica in the range of 48-54% SiO2. The weight ratio of silicon dioxide/potasium solid being 1:1 to 5:1. Silica from geothermal sludge is amorphous, whereas pyrophylite is crystalline phase. The results showed that the amount of raw materials needed to get the appropriate molar ratio of potassium silicate fertilizer grade are different, as well as the fusion temperature of the furnace. Potassium silicate prepared from potassium hydroxide and geothermal sludge produced a low molar ratio (2.5: 1 to 3: 1. The potassium required quite small (4:1 in weight ratio, and on a fusion temperature of about 900 °C. Meanwhile, the potassium silicate prepared from pyrophyllite produced a high molar ratio (1.4 - 9.4 and on a fusion temperature of about 1350 °C, so that potassium needed large enough to meet the required molar ratio for the fertilizer grade. The product potassium silicate solid is amorphous with a little trace of crystalline.

  10. Effects of Long-term Fertilization on Potassium Fixation Capacity in Brown Soil

    Science.gov (United States)

    Li, Na; Guo, Chunlei; Wang, Yue; Gao, Tianyi; Yang, Jinfeng; Han, Xiaori

    2018-01-01

    This study concentrated on the research of features of fixation. The objective of this study was to provide theoretical foundation of rational application of potassium fertilizer along with improving fertilizer availability ratio. A 32 years long-term experiment was conducted to evaluate the effects of fertilizer application on potassium changes and the factors affecting K fixation on brown soil by simulation in laboratory. When the concentration of exogenous potassium was in range of 400∼4000 mg·kg-1, potassium fixation capacity increased along with the rise of concentration of exogenous potassium, whereas K fixation rate reduced; Compared with no-potassium fertilizer, application of potassium fertilizer and organic fertilizer reduced soil potassium fixation capacity. Potassium rate and fixation-release of potassium character in soil should be taken into comprehensive consideration for rational fertilization to maintain or improve soil fertility for increasing potassium fertilizers efficiency in agriculture.

  11. Thanatochemistry: Study of synovial fluid potassium

    African Journals Online (AJOL)

    Nilesh Keshav Tumram

    2014-03-28

    Mar 28, 2014 ... metabolite mainly due to anaerobic glycolysis due to which ac- tive membrane transport stops and loss of selective membrane permeability and diffusion of ions and other parameters according to their concentration gradients starts.2 Further- more, analytical concentrations are influenced by postmortem.

  12. Patterns in potassium dynamics in forest ecosystems.

    Science.gov (United States)

    Tripler, Christopher E; Kaushal, Sujay S; Likens, Gene E; Walter, M Todd

    2006-04-01

    The biotic cycling of potassium (K) in forest systems has been relatively understudied in comparison with nitrogen (N) and phosphorus (P) despite its critical roles in maintaining the nutrition of primary production in forests. We investigated the ecological significance of K in forests from a literature review and data synthesis. We focused on (1) describing patterns of the effects of K availability on aboveground growth and change in foliar tissue of tree species from a variety of forests; and (2) documenting previously unreported relationships between hydrologic losses of K and N in forested watersheds from the Americas. In a review of studies examining tree growth under K manipulations/fertilizations, a high percentage (69% of studies) showed a positive response to increases in K availability in forest soils. In addition, 76% of the tree studies reviewed showed a positive and significant increase in K concentrations in plant tissue after soil K manipulation/fertilization. A meta-analysis on a subset of the reviewed studies was found to provide further evidence that potassium effects tree growth and increased tissue [K] with an effect size of 0.709 for growth and an overall effect size of 0.56. In our review of watershed studies, we observed that concentrations of K typically decreased during growing seasons in streams draining forested areas in the Temperate Zones and were responsive to vegetation disturbance in both temperate and tropical regions. We found a strong relationship (r2 = 0.42-0.99) between concentrations of K and N (another critical plant nutrient) in stream water, suggesting that similar mechanisms of biotic retention may control the flow of these nutrients. Furthermore, K dynamics appear to be unique among the base cations, e.g. calcium, magnesium, and sodium, because the others do not show similar seasonal patterns to K. We suggest that K may be important to the productivity and sustenance of many forests, and its dynamics and ecological

  13. Regulation of ion gradients across myocardial ischemic border zones: a biophysical modelling analysis.

    Directory of Open Access Journals (Sweden)

    Steven Niederer

    Full Text Available The myocardial ischemic border zone is associated with the initiation and sustenance of arrhythmias. The profile of ionic concentrations across the border zone play a significant role in determining cellular electrophysiology and conductivity, yet their spatial-temporal evolution and regulation are not well understood. To investigate the changes in ion concentrations that regulate cellular electrophysiology, a mathematical model of ion movement in the intra and extracellular space in the presence of ionic, potential and material property heterogeneities was developed. The model simulates the spatial and temporal evolution of concentrations of potassium, sodium, chloride, calcium, hydrogen and bicarbonate ions and carbon dioxide across an ischemic border zone. Ischemia was simulated by sodium-potassium pump inhibition, potassium channel activation and respiratory and metabolic acidosis. The model predicted significant disparities in the width of the border zone for each ionic species, with intracellular sodium and extracellular potassium having discordant gradients, facilitating multiple gradients in cellular properties across the border zone. Extracellular potassium was found to have the largest border zone and this was attributed to the voltage dependence of the potassium channels. The model also predicted the efflux of [Formula: see text] from the ischemic region due to electrogenic drift and diffusion within the intra and extracellular space, respectively, which contributed to [Formula: see text] depletion in the ischemic region.

  14. Role of Saccharomyces cerevisiae Trk1 in stabilization of intracellular potassium content upon changes in external potassium levels.

    Science.gov (United States)

    Herrera, Rito; Alvarez, María C; Gelis, Samuel; Kodedová, Marie; Sychrová, Hana; Kschischo, Maik; Ramos, José

    2014-01-01

    Saccharomyces cerevisiae cells are able to grow at very different potassium concentrations adapting its intracellular cation levels to changes in the external milieu. Potassium homeostasis in wild type cells resuspended in media with low potassium is an example of non-perfect adaptation since the same intracellular concentration is not approached irrespective of the extracellular levels of the cation. By using yeasts lacking the Trk1,2 system or expressing different versions of the mutated main plasma membrane potassium transporter (Trk1), we show that Trk1 is not essential for adaptation to potassium changes but the dynamics of potassium loss is very different in the wild type and in trk1,2 mutant or in yeasts expressing Trk1 versions with highly impaired transport characteristics. We also show that the pattern here described can be also fulfilled by heterologous expression of NcHAK1, a potassium transporter not belonging to the TRK family. Hyperpolarization and cationic drugs sensitivity in mutants with defective transport capacity provide additional support to the hypothesis of connections between the activity of the Trk system and the plasma membrane H(+) ATPase (Pma1) in the adaptive process. © 2013.

  15. A Phase 1 dose-ranging study examining the effects of a superabsorbent polymer (CLP) on fluid, sodium and potassium excretion in healthy subjects.

    Science.gov (United States)

    Henderson, Lee W; Dittrich, Howard C; Strickland, Alan; Blok, Thomas M; Newman, Richard; Oliphant, Thomas; Albrecht, Detlef

    2014-01-25

    CLP is an orally administered, non-absorbed, superabsorbent polymer being developed to increase fecal excretion of sodium, potassium and water in patients with heart failure and end-stage renal disease. This study was conducted to evaluate the safety of CLP, and to explore dose-related effects on fecal weight, fecal and urine sodium and potassium excretion, and serum electrolyte concentrations. This Phase 1, open-label, dose-escalation study included 25 healthy volunteers, who were administered CLP orally immediately prior to four daily meals for 9 days at doses of 7.5, 15.0, and 25.0 g/day (n = 5/group). An additional dose group received 15.0 g/day CLP under fasting conditions, and an untreated cohort (n = 5) served as control. Twenty-four-hour fecal and urinary output was collected daily. Samples were weighed, and sodium, potassium, and other ion content in stool and urine were measured for each treatment group. Effects on serum cation concentrations, other standard laboratory values, and adverse events were also determined. At doses below 25.0 g/day, CLP was well tolerated, with a low frequency of self-limiting gastrointestinal adverse events. CLP increased fecal weight and fecal sodium and potassium content in a dose-related manner. Concomitant dose-related decreases in urinary sodium and potassium were observed. All serum ion concentrations remained within normal limits. In this study, oral CLP removed water, sodium and potassium from the body via the gastrointestinal tract in a dose related fashion. CLP could become useful for patients with fluid overload and compromised kidney function in conditions such as congestive heart failure, salt sensitive hypertension, chronic kidney disease and end stage renal disease. NCT01944007.

  16. Incommensurate lattice modulations in Potassium Vanadate

    Science.gov (United States)

    Chakoumakos, Bryan; Banerjee, Arnab; Mark, Lumsden; Cao, Huibo; Kim, Jong-Woo; Hoffman, Christina; Wang, Xiaoping

    Potassium Vanadate (K2V3O8) is an S = 1/2 2D square lattice antiferromagnet that shows spin reorientation indicating a strong coupling between the magnetism and its dielectric properties with a promise of rich physics that promises multiferroicity. These tangible physical properties are strongly tied through a spin-lattice coupling to the underlying lattice and superlattice behavior. It has a superlattice (SL) onsetting below Tc = 115 K with an approximate [3 x 3 x 2] modulation. Here we present our recent experiments at TOPAZ beamline at SNS which for the first time proves conclusively that the lattice modulations are incommensurate, with an in-plane Q of 0.315. We will also show our attempts to refine the data using JANA which requires a redefinition of the lattice, as well as the temperature and Q dependence of the superlattice modulation measured using neutrons at HFIR and synchrotron x-rays at APS. Our results are not only relevant for the ongoing search of multifunctional behavior in K2V3O8 but also generally for the superlattice modulations observed in a large family of fresnoites. Work performed at ORNL and ANL is supported by U.S. Dept. of Energy, Office of Basic Energy Sciences and Office of User Facilities Division.

  17. Sea Anemone Toxins Affecting Potassium Channels

    Science.gov (United States)

    Diochot, Sylvie; Lazdunski, Michel

    The great diversity of K+ channels and their wide distribution in many tissues are associated with important functions in cardiac and neuronal excitability that are now better understood thanks to the discovery of animal toxins. During the past few decades, sea anemones have provided a variety of toxins acting on voltage-sensitive sodium and, more recently, potassium channels. Currently there are three major structural groups of sea anemone K+ channel (SAK) toxins that have been characterized. Radioligand binding and electrophysiological experiments revealed that each group contains peptides displaying selective activities for different subfamilies of K+ channels. Short (35-37 amino acids) peptides in the group I display pore blocking effects on Kv1 channels. Molecular interactions of SAK-I toxins, important for activity and binding on Kv1 channels, implicate a spot of three conserved amino acid residues (Ser, Lys, Tyr) surrounded by other less conserved residues. Long (58-59 amino acids) SAK-II peptides display both enzymatic and K+ channel inhibitory activities. Medium size (42-43 amino acid) SAK-III peptides are gating modifiers which interact either with cardiac HERG or Kv3 channels by altering their voltage-dependent properties. SAK-III toxins bind to the S3C region in the outer vestibule of Kv channels. Sea anemones have proven to be a rich source of pharmacological tools, and some of the SAK toxins are now useful drugs for the diagnosis and treatment of autoimmune diseases.

  18. Implementation and evaluation of a nurse-centered computerized potassium regulation protocol in the intensive care unit - a before and after analysis

    NARCIS (Netherlands)

    Hoekstra, Miriam; Vogelzang, Mathijs; Drost, Jose T.; Janse, Marcel; Loef, Bert G.; van der Horst, Iwan C. C.; Zijlstra, Felix; Nijsten, Maarten W. N.

    2010-01-01

    Background: Potassium disorders can cause major complications and must be avoided in critically ill patients. Regulation of potassium in the intensive care unit (ICU) requires potassium administration with frequent blood potassium measurements and subsequent adjustments of the amount of potassium

  19. Fine structures and ion images on fresh frozen dried ultrathin sections by transmission electron and scanning ion microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Takaya, K.; Okabe, M.; Sawataishi, M.; Takashima, H.; Yoshida, T

    2003-01-15

    Ion microscopy (IM) of air-dried or freeze-dried cryostat and semi-thin cryosections has provided ion images of elements and organic substances in wide areas of the tissue. For reproducible ion images by a shorter time of exposure to the primary ion beam, fresh frozen dried ultrathin sections were prepared by freezing the tissue in propane chilled with liquid nitrogen, cryocut at 60 nm, mounted on grids and silicon wafer pieces, and freeze-dried. Rat Cowper gland and sciatic nerve, bone marrow of the rat administered of lithium carbonate, tree frog and African toad spleen and buffy coat of atopic dermatitis patients were examined. Fine structures and ion images of the corresponding areas in the same or neighboring sections were observed by transmission electron microscopy (TEM) followed by sector type and time-of-flight type IM. Cells in the buffy coat contained larger amounts of potassium and magnesium while plasma had larger amounts of sodium and calcium. However, in the tissues, lithium, sodium, magnesium, calcium and potassium were distributed in the cell and calcium showed a granular appearance. A granular cell of the tree frog spleen contained sodium and potassium over the cell and magnesium and calcium were confined to granules.

  20. Evaluating status change of soil potassium from path model

    National Research Council Canada - National Science Library

    He, Wenming; Chen, Fang

    2013-01-01

    .... In this study, plot experiments were designed into different treatments, and soil samples were collected and further analyzed in laboratory to investigate soil properties influence on soil potassium forms...

  1. Effects of different cavity‑disinfectants and potassium titanyl ...

    African Journals Online (AJOL)

    disinfectants and potassium titanyl phosphate (KTP) laser on microtensile bond strength to primary dentin. Chlorhexidine (CHX), propolis (PRO), ozonated water (OW), gaseous ozone (OG) and KTP laser were used for this purpose. Methodology: ...

  2. Thermal decomposition of potassium bis-oxalatodiaqua-indate (III ...

    Indian Academy of Sciences (India)

    2] 3H2O. Thermal decomposition studies show that the compound decomposes first to the anhydrous potassium indium oxalate ... Bio-inorganic Chemistry Laboratories, School of Chemistry, Andhra University, Visakhapatnam 530 003, India ...

  3. Formulation, Characterization and Physicochemical Evaluation of Potassium Citrate Effervescent Tablets

    National Research Council Canada - National Science Library

    Fatemeh Fattahi; Abolfazl Aslani

    2013-01-01

    Purpose: The aim of this study was to design and formulation of potassium citrate effervescent tablet for reduction of calcium oxalate and urate kidney stones in patients suffering from kidney stones. Methods...

  4. Potassium Ferrate: A Novel Chemical Warfare Agent Decontaminant

    National Research Council Canada - National Science Library

    Greene, Russell; von Fahnestock, F. M; Monzyk, Bruce

    2004-01-01

    ..., and/or unsatisfactory CWA destruction efficiencies. Potassium ferrate (K2FeO4) addresses all of these issues through its high oxidation potential, stable shelf life, and benign reduced state, namely iron oxide...

  5. A Simplified Extemporaneously Prepared Potassium Chloride Oral Solution.

    Science.gov (United States)

    Tannous, Elias; Tal, Yana; Amarny, Kamal

    2016-01-01

    Although commercial preparations of oral potassium supplements are usually available, there are times when our Medical Center is faced with situations in which the oral solution of potassium chloride is not available. This solution is necessary for our pediatric outpatients who cannot swallow tablets and need an oral solution. Moreover, there are no studies available which describe an extemporaneously prepared potassium chloride oral solution on which we can rely for assigning a beyond-use date. The aim of this study was to formulate an extemporaneous pediatric oral solution of potassium chloride and to determine the physical and chemical stability of this preparation. We prepared 1 mMoL/mL by withdrawing 25 mL of potassium chloride 14.9%. Ora-Sweet SF was added to 50 mL in a metered flask. The solution was kept refrigerated (2°C to 8°C). Samples were withdrawn to measure potassium concentration, pH, and microbial overgrowth. The test was performed by our biochemical laboratory. The oral solution of potassium chloride 1 mMoL/mL stored at 2°C to 8°C maintained at least 91% of the initial concentration for 28 days. There were no notable changes in pH, and the solution remained physically stable with no visual microbial growth. The oral solution of potassium chloride 1 mMoL/mL prepared in Ora-Sweet and stored at 2°C to 8°C in amber glass bottles is expected to remain stable for 28 days. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

  6. Formulation, Characterization and Physicochemical Evaluation of Potassium Citrate Effervescent Tablets

    OpenAIRE

    Fatemeh Fattahi; Abolfazl Aslani

    2013-01-01

    Purpose: The aim of this study was to design and formulation of potassium citrate effervescent tablet for reduction of calcium oxalate and urate kidney stones in patients suffering from kidney stones. Methods: In this study, 13 formulations were prepared from potassium citrate and effervescent base in different concentration. The flowability of powders and granules was studied. Then effervescent tablets were prepared by direct compression, fusion and wet granulation methods. The prepared tabl...

  7. Optimizing potassium ferrate for textile wastewater treatment by RSM

    Directory of Open Access Journals (Sweden)

    Maryam Moradnia

    2016-08-01

    Full Text Available Background: Application of potassium ferrate is a chemical oxidation approach used for water and wastewater treatment. The aim of this study is to apply central composite design (CCD and response surface methodology (RSM to optimize potassium ferrate consumption in the treatment of wastewater from carpet industries. Methods: Samples in this experimental study were collected from wastewater, originating from a carpet factory. Wastewater sampling was carried out monthly for a period of two seasons. Ferrate oxidation experiments were conducted by means of a conventional jar-test apparatus. The time and speed for mixing were set with an automatic controller. Parameters of study were measured based on given methodologies in Standard method for examining water and wastewater. CCD and RSM were applied to optimize the operating variables including potassium ferrate dosage and pH. Results: Results showed that potassium ferrate concentration (A, pH (B, their interactions (AB and quadratic effects (A2 and B2 were significant in the removal of COD, turbidity, color and TSS from carpet industries effluents. At an optimum point (COD: 160 mg/L of potassium ferrate and pH 4, turbidity: 165 mg/L of potassium ferrate and pH 4, color and TSS: pH 4.5 and 150 mg/L of potassium ferrate removal efficiencies for COD, turbidity, color and TSS were 86, 86, 87 and 89%, respectively. Conclusion: Potassium ferrate has a significant impact on pollutants decomposition and the removal of color from wastewater produced in carpet industries. This process can be employed for the pretreatment or post treatment of wastewaters containing refractory organic pollutants. CCD and RSM are suitable tools for experimental design.

  8. Optimizing potassium ferrate for textile wastewater treatment by RSM

    OpenAIRE

    Maryam Moradnia; Masoud Panahifard; Kavoos Dindarlo; Hamzeh Ali Jamali

    2016-01-01

    Background: Application of potassium ferrate is a chemical oxidation approach used for water and wastewater treatment. The aim of this study is to apply central composite design (CCD) and response surface methodology (RSM) to optimize potassium ferrate consumption in the treatment of wastewater from carpet industries. Methods: Samples in this experimental study were collected from wastewater, originating from a carpet factory. Wastewater sampling was carried out monthly for a p...

  9. Evaluating status change of soil potassium from path model.

    Directory of Open Access Journals (Sweden)

    Wenming He

    Full Text Available The purpose of this study is to determine critical environmental parameters of soil K availability and to quantify those contributors by using a proposed path model. In this study, plot experiments were designed into different treatments, and soil samples were collected and further analyzed in laboratory to investigate soil properties influence on soil potassium forms (water soluble K, exchangeable K, non-exchangeable K. Furthermore, path analysis based on proposed path model was carried out to evaluate the relationship between potassium forms and soil properties. Research findings were achieved as followings. Firstly, key direct factors were soil S, ratio of sodium-potassium (Na/K, the chemical index of alteration (CIA, Soil Organic Matter in soil solution (SOM, Na and total nitrogen in soil solution (TN, and key indirect factors were Carbonate (CO3, Mg, pH, Na, S, and SOM. Secondly, path model can effectively determine direction and quantities of potassium status changes between Exchangeable potassium (eK, Non-exchangeable potassium (neK and water-soluble potassium (wsK under influences of specific environmental parameters. In reversible equilibrium state of [Formula: see text], K balance state was inclined to be moved into β and χ directions in treatments of potassium shortage. However in reversible equilibrium of [Formula: see text], K balance state was inclined to be moved into θ and λ directions in treatments of water shortage. Results showed that the proposed path model was able to quantitatively disclose moving direction of K status and quantify its equilibrium threshold. It provided a theoretical and practical basis for scientific and effective fertilization in agricultural plants growth.

  10. Changes in plasma potassium concentration during carbon dioxide pneumoperitoneum

    DEFF Research Database (Denmark)

    Perner, A; Bugge, K; Lyng, K M

    1999-01-01

    Hyperkalaemia with ECG changes had been noted during prolonged carbon dioxide pneumoperitoneum in pigs. We have compared plasma potassium concentrations during surgery in 11 patients allocated randomly to undergo either laparoscopic or open appendectomy and in another 17 patients allocated randomly...... to either carbon dioxide pneumoperitoneum or abdominal wall lifting for laparoscopic colectomy. Despite an increasing metabolic acidosis, prolonged carbon dioxide pneumoperitoneum resulted in only a slight increase in plasma potassium concentrations, which was both statistically and clinically insignificant...

  11. Abnormalities of the five serum ions in patients with Leber congenital amaurosis

    Directory of Open Access Journals (Sweden)

    Zhi-Zhong Wu

    2017-03-01

    Full Text Available AIM:To study the concentration changes of the serum magnesium, calcium, potassium, sodium and chloride ions of the patients of Leber congenital amaurosis(LCA.METHODS:Based on the retrospective study and the simple size in the statistics, 50 cases of LCA patients and 99 cases of normal people were tested the serum ions by professionals in hospital according to the single blind study. Data were analyzed statistically between LCA and normal groups. RESULTS: In the clinical serum ions test of LCA group, the concentration of calcium and potassium were 2.338±0.090mmol/L and 4.164±0.356mmol/L respectively, which were significantly higher than those of the normal group(all PPP>0.05. CONCLUSION: In the patients with LCA, abnormal concentration changes of magnesium, calcium and potassium will be needed to concern of the ophthalmologist, which is probably related with the occurrence of LCA.

  12. Potassium application to table grape clusters after veraison increases soluble solids by enhancing berry water loss

    Science.gov (United States)

    Potassium salt solutions were applied twice to clusters of several table grapes cultivars, after the onset of veraison and three weeks later. Potassium bicarbonate, potassium sorbate, and glycine-complexed potassium, a commercial fertilizer product, increased soluble solids content consistently, whi...

  13. Mechanisms of valence selectivity in biological ion channels.

    Science.gov (United States)

    Corry, B; Chung, S-H

    2006-02-01

    Transmembrane ion channels play a crucial role in the existence of all living organisms. They partition the exterior from the interior of the cell, maintain the proper ionic gradient across the cell membrane and facilitate signaling between cells. To perform these functions, ion channels must be highly selective, allowing some types of ions to pass while blocking the passage of others. Here we review a number of studies that have helped to elucidate the mechanisms by which ion channels discriminate between ions of differing charge, focusing on four channel families as examples: gramicidin, ClC chloride, voltage-gated calcium and potassium channels. The recent availability of high-resolution structural data has meant that the specific inter-atomic interactions responsible for valence selectivity can be pinpointed. Not surprisingly, electrostatic considerations have been shown to play an important role in ion specificity, although many details of the origins of this discrimination remain to be determined.

  14. Selection of inhibitor-resistant viral potassium channels identifies a selectivity filter site that affects barium and amantadine block.

    Directory of Open Access Journals (Sweden)

    Franck C Chatelain

    Full Text Available BACKGROUND: Understanding the interactions between ion channels and blockers remains an important goal that has implications for delineating the basic mechanisms of ion channel function and for the discovery and development of ion channel directed drugs. METHODOLOGY/PRINCIPAL FINDINGS: We used genetic selection methods to probe the interaction of two ion channel blockers, barium and amantadine, with the miniature viral potassium channel Kcv. Selection for Kcv mutants that were resistant to either blocker identified a mutant bearing multiple changes that was resistant to both. Implementation of a PCR shuffling and backcrossing procedure uncovered that the blocker resistance could be attributed to a single change, T63S, at a position that is likely to form the binding site for the inner ion in the selectivity filter (site 4. A combination of electrophysiological and biochemical assays revealed a distinct difference in the ability of the mutant channel to interact with the blockers. Studies of the analogous mutation in the mammalian inward rectifier Kir2.1 show that the T-->S mutation affects barium block as well as the stability of the conductive state. Comparison of the effects of similar barium resistant mutations in Kcv and Kir2.1 shows that neighboring amino acids in the Kcv selectivity filter affect blocker binding. CONCLUSIONS/SIGNIFICANCE: The data support the idea that permeant ions have an integral role in stabilizing potassium channel structure, suggest that both barium and amantadine act at a similar site, and demonstrate how genetic selections can be used to map blocker binding sites and reveal mechanistic features.

  15. Selection of Inhibitor-Resistant Viral Potassium Channels Identifies a Selectivity Filter Site that Affects Barium and Amantadine Block

    Science.gov (United States)

    Fujiwara, Yuichiro; Arrigoni, Cristina; Domigan, Courtney; Ferrara, Giuseppina; Pantoja, Carlos; Thiel, Gerhard; Moroni, Anna; Minor, Daniel L.

    2009-01-01

    Background Understanding the interactions between ion channels and blockers remains an important goal that has implications for delineating the basic mechanisms of ion channel function and for the discovery and development of ion channel directed drugs. Methodology/Principal Findings We used genetic selection methods to probe the interaction of two ion channel blockers, barium and amantadine, with the miniature viral potassium channel Kcv. Selection for Kcv mutants that were resistant to either blocker identified a mutant bearing multiple changes that was resistant to both. Implementation of a PCR shuffling and backcrossing procedure uncovered that the blocker resistance could be attributed to a single change, T63S, at a position that is likely to form the binding site for the inner ion in the selectivity filter (site 4). A combination of electrophysiological and biochemical assays revealed a distinct difference in the ability of the mutant channel to interact with the blockers. Studies of the analogous mutation in the mammalian inward rectifier Kir2.1 show that the T→S mutation affects barium block as well as the stability of the conductive state. Comparison of the effects of similar barium resistant mutations in Kcv and Kir2.1 shows that neighboring amino acids in the Kcv selectivity filter affect blocker binding. Conclusions/Significance The data support the idea that permeant ions have an integral role in stabilizing potassium channel structure, suggest that both barium and amantadine act at a similar site, and demonstrate how genetic selections can be used to map blocker binding sites and reveal mechanistic features. PMID:19834614

  16. Genetic control of potassium content of common bean seeds

    Directory of Open Access Journals (Sweden)

    Nerison Luís Poersch

    2011-06-01

    Full Text Available The objective of this work was to investigate possible maternal effects on potassium content of common bean seeds, as well as to estimate the heritability and selection gains in early hybrid generations for this character and to evaluate the efficiency of genetic selection to improve the nutritional quality of common bean (Phaseolus vulgaris. Crosses with four cultivars from the Mesoamerican gene pool yielded the reciprocal F1 and F2 generations and the backcrossed populations (BCP1 and BCP2. The potassium content of the progenies was measured via nitric‑perchloric digestion and flame photometry. The potassium content in the tested progenies varied from 6.0 to 14.9 g kg-1 dry matter, and no significant maternal effect was observed. The narrow-sense heritability ranged from low (33.26% to intermediate (43.05%. Partial dominance was observed for low potassium content in the seeds. No increase in potassium content was obtained through selection. Breeding common bean plants for increasing potassium content in seeds may be difficult because the local environment strongly influences the character.

  17. Potassium-doped n-type bilayer graphene

    Science.gov (United States)

    Yamada, Takatoshi; Okigawa, Yuki; Hasegawa, Masataka

    2018-01-01

    Potassium-doped n-type bilayer graphene was obtained. Chemical vapor deposited bilayer and single layer graphene on copper (Cu) foils were used. After etching of Cu foils, graphene was dipped in potassium hydroxide aqueous solutions to dope potassium. Graphene on silicon oxide was characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and Raman spectroscopy. Both XPS and EDX spectra indicated potassium incorporation into the bilayer graphene via intercalation between the graphene sheets. The downward shift of the 2D peak position of bilayer graphene after the potassium hydroxide (KOH) treatment was confirmed in Raman spectra, indicating that the KOH-treated bilayer graphene was doped with electrons. Electrical properties were measured using Hall bar structures. The Dirac points of bilayer graphene were shifted from positive to negative by the KOH treatment, indicating that the KOH-treated bilayer graphene was n-type conduction. For single layer graphene after the KOH treatment, although electron doping was confirmed from Raman spectra, the peak of potassium in the X-ray photoelectron spectroscopy (XPS) spectrum was not detected. The Dirac points of single layer graphene with and without the KOH treatment showed positive.

  18. BILAYER LIPID MEMBRANE (BLM) BASED ION SELECTIVE ELECTRODES AT THE MESO, MICRO, AND NANO SCALES

    Science.gov (United States)

    Liu, Bingwen; Rieck, Daniel; Van Wie, Bernard J.; Cheng, Gary J.; Moffett, David F.; Kidwell, David A.

    2009-01-01

    This paper presents a novel method for making micron-sized apertures with tapered sidewalls and nano-sized apertures. Their use in bilayer lipid membrane-based ion selective electrode design is demonstrated and compared to mesoscale bilayers and traditional PVC ion selective electrodes. Micron-sized apertures are fabricated in SU-8 photoresist films and vary in diameter from 10 to 40 microns. The tapered edges in SU-8 films are desired to enhance bilayer lipid membrane (BLM) formation and are fabricated by UV-light overexposure. Nanoapertures are made in boron diffused silicon film. The membranes are used as septa to separate two potassium chloride solutions of different concentrations. Lecithin BLMs are assembled on the apertures by ejecting lipid solution. Potassium ionophore, dibenzo-18-crown-6, is incorporated into BLMs by dissolving it in the lipid solution before membrane assembly. Voltage changes with increasing potassium ion concentrations are recorded with an A/D converter. Various ionophore concentrations in BLMs are investigated. At least a 1% concentration is needed for consistent slopes. Electrode response curves are linear over the 10−6 to 0.1 M range with a sub-Nernstian slope of 20 mV per Log concentration change. This system shows high selectivity to potassium ions over potential interfering sodium ions. BLMs on the three different aperture sizes at the meso, micro, and nano-scales all show similar linear ranges and limits of detection (LODs) as PVC ion selective membranes. PMID:19008091

  19. The relationship between serum potassium, potassium variability and in-hospital mortality in critically ill patients and a before-after analysis on the impact of computer-assisted potassium control

    NARCIS (Netherlands)

    Hessels, Lara; Hoekstra, Miriam; Mijzen, Lisa J.; Vogelzang, Mathijs; Dieperink, Wim; Oude Lansink, Annemieke; Nijsten, Maarten W.

    2015-01-01

    Introduction: The relationship between potassium regulation and outcome is not known. Our first aim in the present study was to determine the relationship between potassium level and variability in (ICU) stay and outcome. The second aim was to evaluate the impact of a computer-assisted potassium

  20. Potassium is a key signal in host-microbiome dysbiosis in periodontitis.

    Directory of Open Access Journals (Sweden)

    Susan Yost

    2017-06-01

    Full Text Available Dysbiosis, or the imbalance in the structural and/or functional properties of the microbiome, is at the origin of important infectious inflammatory diseases such as inflammatory bowel disease (IBD and periodontal disease. Periodontitis is a polymicrobial inflammatory disease that affects a large proportion of the world's population and has been associated with a wide variety of systemic health conditions, such as diabetes, cardiovascular and respiratory diseases. Dysbiosis has been identified as a key element in the development of the disease. However, the precise mechanisms and environmental signals that lead to the initiation of dysbiosis in the human microbiome are largely unknown. In a series of previous in vivo studies using metatranscriptomic analysis of periodontitis and its progression we identified several functional signatures that were highly associated with the disease. Among them, potassium ion transport appeared to be key in the process of pathogenesis. To confirm its importance we performed a series of in vitro experiments, in which we demonstrated that potassium levels a increased the virulence of the oral community as a whole and at the same time altering the immune response of gingival epithelium, increasing the production of TNF-α and reducing the expression of IL-6 and the antimicrobial peptide human β-defensin 3 (hBD-3. These results indicate that levels of potassium in the periodontal pocket could be an important element in of dysbiosis in the oral microbiome. They are a starting point for the identification of key environmental signals that modify the behavior of the oral microbiome from a symbiotic community to a dysbiotic one.

  1. Crystal Structure of the Sodium-Potassium Pump (Na⁺, K⁺-ATPase) with Bound Potassium and Ouabain

    National Research Council Canada - National Science Library

    Haruo Ogawa; Takehiro Shinoda; Flemming Cornelius; Chikashi Toyoshima

    2009-01-01

    The sodium-potassium pump (Na⁺,K⁺-ATPase) is responsible for establishing Na⁺ and K⁺ concentration gradients across the plasma membrane and therefore plays an essential role in, for instance, generating action potentials...

  2. Tomato yield and potassium concentrations in soil and in plant petioles as affected by potassium fertirrigation

    Directory of Open Access Journals (Sweden)

    FONTES PAULO CEZAR REZENDE

    2000-01-01

    Full Text Available Tomato (Lycopersicon esculentum Mill. cv. Santa Clara was grown on a silt clay soil with 46 mg dm-3 Mehlich 1 extractable K, to evaluate the effects of trickle-applied K rates on fruit yield and to establish K critical concentrations in soil and in plant petioles. Six potassium rates (0, 48, 119, 189, 259 and 400 kg ha-1 K were applied in a randomized complete block design with four replications. Soil and plant K critical levels were determined at two plant growth stages (at the beginning of the second and fourth cluster flowering. Total, marketable and weighted yields increased with K rates, reaching their maximum of 86.4, 73.4, and 54.9 ton ha-1 at 198, 194, and 125 kg ha-1 K , respectively. At the first soil sampling date K critical concentrations in the soil associated with K rates for maximum marketable and weighted yields were 92 and 68 mg dm-3, respectively. Potassium critical concentrations in the dry matter of the petioles sampled by the beginning of the second and fourth cluster flowering time, associated with maximum weighted yield, were 10.30 and 7.30 dag kg-1, respectively.

  3. Crown-Ether Derived Graphene Hybrid Composite for Membrane-Free Potentiometric Sensing of Alkali Metal Ions

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-01

    We report the design and synthesis of newly functionalized graphene hybrid material that can be used for selective membrane-free potentiometric detection of alkali metal ions, represented by potassium ions. Reduced graphene oxide (RGO) functionalized covalently by 18-crown[6] ether with a dense...

  4. Solvent Extraction and Ion Exchange in Radiochemistry

    Science.gov (United States)

    Skarnemark, G.

    In 1805, Bucholz extracted uranium from a nitric acid solution into ether and back-extracted it into pure water. This is probably the first reported solvent-extraction investigation. During the following decades, the distribution of neutral compounds between aqueous phases and pure solvents was studied, e.g., by Peligot, Berthelot and Jungfleisch, and Nernst. Selective extractants for analytical purposes became available during the first decades of the twentieth century. From about 1940, extractants such as organophosphorous esters and amines were developed for use in the nuclear fuel cycle. This connection between radiochemistry and solvent-extraction chemistry made radiochemists heavily involved in the development of new solvent extraction processes, and eventually solvent extraction became a major separation technique in radiochemistry. About 160 years ago, Thompson and Way observed that soil can remove potassium and ammonium ions from an aqueous solution and release calcium ions. This is probably the first scientific report on an ion-exchange separation. The first synthesis of the type of organic ion exchangers that are used today was performed by Adams and Holmes in 1935. Since then, ion-exchange techniques have been used extensively for separations of various radionuclides in trace as well as macro amounts. During the last 4 decades, inorganic ion exchangers have also found a variety of applications. Today, solvent extraction as well as ion exchange are used extensively in the nuclear industry and for nuclear, chemical, and medical research. Some of these applications are discussed in the chapter.

  5. The Effect of Potassium on the Controlling of Salt in Evening Primrose (Oenothera macrocarpa

    Directory of Open Access Journals (Sweden)

    M. Goldani

    2016-07-01

    Full Text Available Introduction: Salinity has been recognized as one of the major abiotic factors affecting crop yields in arid and semi-arid irrigated areas of the world and efforts for breeding salt-resistant crop plants have been made. Approximately one-third of the world irrigated soils and a large proportion of soils in dry land are saline. Two major effects have been identified as the probable causes of high salt toxicity in crop plant i.e., the ionic effect and the osmotic effect. The ionic effect results in alterations in enzymatic processes, disturbances in accumulation and transport of different ions or a combination of all these factors. As a result, shoot and root growing reduce and uptake of nutrient elements by plants is adversely affected. While excess Na accumulated in plants under salinity stress conditions hinders K uptake; Cl hinders NO3 uptake by plants and destroys ionic balance in plants. Evening primrose is a plant which belongs to Onagraceae. Its seed oil has a special arrangement in Glycerol molecule, so it has been used a lot in medical treatments and also feeding. Researchers showed that using the best techniques and methods in farming can increase the amount of oil in the seeds of this plant. The wrong method of agricultural activities in Iran caused increasing salt in the soil, so growing plants in this situation isn’t possible. For confronting with this phenomenon knowing and choosing kinds of plants that can resist the situation of salt is really a necessary. Materials and Methods: This study was conducted as a factorial experiment based on completely randomized design with three replicates was performed with five levels of NaCl salinity on Oenothera macrocarpa (0, 30, 60, 90 and 120 mM and potassium chloride levels (zero and 15.02 mM and three times in the Faculty of Agriculture, Ferdowsi University of Mashhad in 1390. Salt treatment to prevent osmotic shock was applied to four-leaf stage and treated with potassium was gradually

  6. Cholesterol influences potassium currents in inner hair cells isolated from guinea pig cochlea.

    Science.gov (United States)

    Kimitsuki, Takashi

    2017-02-01

    There is a correlation between serum hyperlipidemia and hearing loss. Cholesterol is an integral component of the cell membrane and regulates the activity of ion channels in the lipid bilayer. The aim of this study was to investigate the effects of cholesterol on the potassium currents in IHCs by using the cholesterol-depleting drug, MβCD, and water-soluble cholesterol. IHCs were acutely isolated from a mature guinea-pig cochlea and potassium currents were recorded. MβCD and water-soluble cholesterol were applied to IHCs under pressure puff pipettes. IHCs showed outwardly rectifying currents (IK,f and IK,s) in response to depolarizing voltage pulses, with only a slight inward current (IK,n) when hyperpolarized. In 10mM MβCD solutions, the amplitude of outward K currents reversely decreased; however, fast activation kinetics was preserved. In contrast, in solution of 1mM water-soluble cholesterol, the amplitude of outward K currents reversely increased. At the membrane potential of +110mV, relative conductances were 0.87±0.07 and 1.18±0.11 in MβCD solutions and cholesterol solutions, respectively. The amplitude of K currents in isolated IHCs was reversely changed by cholesterol-depleting drug and water-soluble cholesterol. These results demonstrated the possibility of the involvement of IHC function in hyperlipidemia-induced inner ear disorders. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Inwardly rectifying potassium channels influence Drosophila wing morphogenesis by regulating Dpp release.

    Science.gov (United States)

    Dahal, Giri Raj; Pradhan, Sarala Joshi; Bates, Emily Anne

    2017-08-01

    Loss of embryonic ion channel function leads to morphological defects, but the underlying reason for these defects remains elusive. Here, we show that inwardly rectifying potassium (Irk) channels regulate release of the Drosophila bone morphogenetic protein Dpp in the developing fly wing and that this is necessary for developmental signaling. Inhibition of Irk channels decreases the incidence of distinct Dpp-GFP release events above baseline fluorescence while leading to a broader distribution of Dpp-GFP. Work by others in different cell types has shown that Irk channels regulate peptide release by modulating membrane potential and calcium levels. We found calcium transients in the developing wing, and inhibition of Irk channels reduces the duration and amplitude of calcium transients. Depolarization with high extracellular potassium evokes Dpp release. Taken together, our data implicate Irk channels as a requirement for regulated release of Dpp, highlighting the importance of the temporal pattern of Dpp presentation for morphogenesis of the wing. © 2017. Published by The Company of Biologists Ltd.

  8. Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth.

    Science.gov (United States)

    Jackson, W F

    2017-01-01

    Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+, and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. VSM cells express multiple isoforms of at least five classes of K+ channels that contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression, and function of large conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells. © 2017 Elsevier Inc. All rights reserved.

  9. Precipitation Reaction of SDS and Potassium Salts in Flocculation of a Micronized Megestrol Acetate Suspension.

    Science.gov (United States)

    Hejazi, Seyed Mahdi; Erfan, Mohammad; Mortazavi, Seyed Alireza

    2013-01-01

    In this work attempts were made to evaluate K+-SDS and hydrocolloid polymer-SDS interactions in flocculation of megestrol acetate dispersions to enhance their stability as a part of suspension formulation. Different dispersions of micronized megestrol acetate and SDS were prepared. KCl and KH2PO4 and their corresponding sodium salts were added to the dispersions and the preparations were evaluated using general physicochemical and stability tests including appearance, sedimentation volume, sedimentation rate and redispersibility. Addition of polyols and hydrocolloid polymers to the SDS containing dispersions was also investigated for possible instabilities. SDS deflocculated the initial megestrol acetate dispersions. The use of potassium salts unlike the sodium salts flocculated the dispersion particles due to precipitation reaction of potassium ions and the adsorbed SDS. Additionally the uncharged hydrocolloid polymers MC and HPMC in contrast to the ionic polymers xanthan gum and NaCMC showed incompatibility due to their interaction with SDS. K(+)- SDS interactions have proved useful in protein and DNA analysis studies and we found this precipitation reaction to be applicable in flocculation of pharmaceutical suspensions containing SDS.

  10. The thermosensitive potassium channel TREK-1 contributes to coolness-evoked responses of Grueneberg ganglion neurons.

    Science.gov (United States)

    Stebe, Sabrina; Schellig, Katharina; Lesage, Florian; Breer, Heinz; Fleischer, Joerg

    2014-01-01

    Neurons of the Grueneberg ganglion (GG) residing in the vestibule of the murine nose are activated by cool ambient temperatures. Activation of thermosensory neurons is usually mediated by thermosensitive ion channels of the transient receptor potential (TRP) family. However, there is no evidence for the expression of thermo-TRPs in the GG, suggesting that GG neurons utilize distinct mechanisms for their responsiveness to cool temperatures. In search for proteins that render GG neurons responsive to coolness, we have investigated whether TREK/TRAAK channels may play a role; in heterologous expression systems, these potassium channels have been previously found to close upon exposure to coolness, leading to a membrane depolarization. The results of the present study indicate that the thermosensitive potassium channel TREK-1 is expressed in those GG neurons that are responsive to cool temperatures. Studies analyzing TREK-deficient mice revealed that coolness-evoked responses of GG neurons were clearly attenuated in these animals compared with wild-type conspecifics. These data suggest that TREK-1 channels significantly contribute to the responsiveness of GG neurons to cool temperatures, further supporting the concept that TREK channels serve as thermoreceptors in sensory cells. Moreover, the present findings provide the first evidence of how thermosensory GG neurons are activated by given temperature stimuli in the absence of thermo-TRPs.

  11. Protonated form: the potent form of potassium-competitive acid blockers.

    Directory of Open Access Journals (Sweden)

    Hua-Jun Luo

    Full Text Available Potassium-competitive acid blockers (P-CABs are highly safe and active drugs targeting H+,K+-ATPase to cure acid-related gastric diseases. In this study, we for the first time investigate the interaction mechanism between the protonated form of P-CABs and human H+,K+-ATPase using homology modeling, molecular docking, molecular dynamics and binding free energy calculation methods. The results explain why P-CABs have higher activities with higher pKa values or at lower pH. With positive charge, the protonated forms of P-CABs have more competitive advantage to block potassium ion into luminal channel and to bind with H+,K+-ATPase via electrostatic interactions. The binding affinity of the protonated form is more favorable than that of the neutral P-CABs. In particular, Asp139 should be a very important binding site for the protonated form of P-CABs through hydrogen bonds and electrostatic interactions. These findings could promote the rational design of novel P-CABs.

  12. Protonated form: the potent form of potassium-competitive acid blockers.

    Science.gov (United States)

    Luo, Hua-Jun; Deng, Wei-Qiao; Zou, Kun

    2014-01-01

    Potassium-competitive acid blockers (P-CABs) are highly safe and active drugs targeting H+,K+-ATPase to cure acid-related gastric diseases. In this study, we for the first time investigate the interaction mechanism between the protonated form of P-CABs and human H+,K+-ATPase using homology modeling, molecular docking, molecular dynamics and binding free energy calculation methods. The results explain why P-CABs have higher activities with higher pKa values or at lower pH. With positive charge, the protonated forms of P-CABs have more competitive advantage to block potassium ion into luminal channel and to bind with H+,K+-ATPase via electrostatic interactions. The binding affinity of the protonated form is more favorable than that of the neutral P-CABs. In particular, Asp139 should be a very important binding site for the protonated form of P-CABs through hydrogen bonds and electrostatic interactions. These findings could promote the rational design of novel P-CABs.

  13. A novel colorimetric potassium sensor based on the substitution of lead from G-quadruplex.

    Science.gov (United States)

    Sun, Huijiao; Li, Xiaohong; Li, Yunchao; Fan, Louzhen; Kraatz, Heinz-Bernhard

    2013-02-21

    Potassium ions play diverse roles in biological processes, and abnormal K(+) levels are the hallmarks of diseases. However, the potential clinical application of the developed DNA-based K(+) sensors remains a challenge due to the presence of Pb(2+) in blood samples. In this contribution, a novel colorimetric potassium sensing assay that functions in the presence of Pb(2+) is reported. This approach is based on conformational switching of a hairpin DNA structure to a G-quadruplex. Specifically, the hairpin DNA containing G-rich aptamer T30695 is exposed to successive amounts of Na(+), Pb(2+) and K(+). These cations induce formation of the corresponding metal-stabilized G-quadruplex, which acts as DNAzyme (with hemin as a cofactor) for the catalytic oxidation of ABTS by H(2)O(2). Importantly, studies presented here show that K(+) replaces Pb(2+) from the G-quadruplex to form K(+)-stabilized G-quadruplex, which differ in the catalytic behavior. With Pb(2+)-stabilized G-quadruplex as a probe, a highly sensitive and selective colorimetric detection of K(+) is achieved in the presence of Pb(2+) and excessive Na(+) (140 mM) with the detection limit of 1.9 nM. This system represents the first known DNAzyme-based colorimetric K(+) sensor, which works in the presence of Pb(2+). Finally, the sensor is successfully applied for K(+) detection in a real human serum sample containing Pb(2+).

  14. Lead removal from aqueous solutions by potassium titanate doped with silica; Remocion de plomo de soluciones acuosas por titanato de potasio dopado con silice

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar G, M. A.; Aguilar E, A. [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes No. 120, 31109 Chihuahua (Mexico); Gorokhovsky, A. V.; Escalante G, J. I. [Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Carretera Saltillo-Mty Km. 13, Apdo. Postal 663, Saltillo 25000, Coahuila (Mexico)], e-mail: mgzlz@hotmail.com

    2009-07-01

    This paper is related to elimination of Pb{sup 2+} ions from aqueous solutions by adsorption in potassium tetra titanate doped with silica. The adsorbent was prepared in the form of granules with pastes of potassium poly titanate (45 %), powdered Pyrex glass (5 %) and potato starch (50 %), which were extruded and thermally treated at 1100 C. The structural characteristic of the granulated adsorbent allows reducing the Pb concentration, from the solutions eluted through an adsorption column, to levels below the requirement of national standards. The effects of the time of saturation of the adsorbent and the ph of the solution were also investigated on the effectiveness of the adsorption of Pb. The mechanism of lead adsorption, by the developed adsorbent, is considered as a combination of adsorption, ion-exchange and co-precipitation processes. It is also shown that the lead-saturated adsorbent could be utilized to produce high-strength non-dangerous ceramic materials. (Author)

  15. Graphene Visualizes the Ion Distribution on Air-Cleaved Mica

    Science.gov (United States)

    Bampoulis, Pantelis; Sotthewes, Kai; Siekman, Martin H.; Zandvliet, Harold J. W.; Poelsema, Bene

    2017-03-01

    The distribution of potassium (K+) ions on air-cleaved mica is important in many interfacial phenomena such as crystal growth, self-assembly and charge transfer on mica. However, due to experimental limitations to nondestructively probe single ions and ionic domains, their exact lateral organization is yet unknown. We show, by the use of graphene as an ultra-thin protective coating and scanning probe microscopies, that single potassium ions form ordered structures that are covered by an ice layer. The K+ ions prefer to minimize the number of nearest neighbour K+ ions by forming row-like structures as well as small domains. This trend is a result of repulsive ionic forces between adjacent ions, weakened due to screening by the surrounding water molecules. Using high resolution conductive atomic force microscopy maps, the local conductance of the graphene is measured, revealing a direct correlation between the K+ distribution and the structure of the ice layer. Our results shed light on the local distribution of ions on the air-cleaved mica, solving a long-standing enigma. They also provide a detailed understanding of charge transfer from the ionic domains towards graphene.

  16. Coupled ion Binding and Structural Transitions Along the Transport Cycle of Glutamate Transporters

    Energy Technology Data Exchange (ETDEWEB)

    Verdon, Gregory [Weill Cornell Medical College, New York, NY (United States); Oh, SeCheol [Weill Cornell Medical College, New York, NY (United States); Serio, Ryan N. [Weill Cornell Medical College, New York, NY (United States); Boudker, Olga [Weill Cornell Medical College, New York, NY (United States)

    2014-05-19

    Membrane transporters that clear the neurotransmitter glutamate from synapses are driven by symport of sodium ions and counter-transport of a potassium ion. Previous crystal structures of a homologous archaeal sodium and aspartate symporter showed that a dedicated transport domain carries the substrate and ions across the membrane. We report new crystal structures of this homologue in ligand-free and ions-only bound outward- and inward-facing conformations. We then show that after ligand release, the apo transport domain adopts a compact and occluded conformation that can traverse the membrane, completing the transport cycle. Sodium binding primes the transport domain to accept its substrate and triggers extracellular gate opening, which prevents inward domain translocation until substrate binding takes place. Moreover, we describe a new cation-binding site ideally suited to bind a counter-transported ion. We suggest that potassium binding at this site stabilizes the translocation-competent conformation of the unloaded transport domain in mammalian homologues.

  17. Polymer Inclusion Membranes (PIM for the Recovery of Potassium in the Presence of Competitive Cations

    Directory of Open Access Journals (Sweden)

    Anna Casadellà

    2016-03-01

    Full Text Available Potassium is an important nutrient used in fertilizers but is not always naturally available  We investigated the properties of polymer inclusion membranes (PIM regarding their selective recovery of K+ over competitive ions typically present in urine (Na+ and NH4+. The greatest flux was observed when the ratio of mass 2-nitrophenyl octyl ether (2-NPOE used as plasticizer to cellulose triacetate (CTA used as polymer was 0.25. The highest flux was achieved with a content of 24.8 wt % of dicyclohexan-18-crown-6 (DCH18C6 used as carrier, although the highest selectivity was observed with a content of 14.0 wt % of DCH18C6. We also studied whether the transport mechanism occurring in our system was based on co-transport of a counter-ion or ion exchange. Two different receiving phases (ultrapure water and 100 mM HCl were tested. Results on transport mechanisms suggest that co-transport of cations and anions is taking place across our PIMs. The membrane deteriorated and lost its properties when the receiving phase was acidic; we suggested that this was due to hydrolysis of CTA. The greatest flux and selectivity were observed in ultrapure water as receiving phase.

  18. Gas Desorption and Electron Emission from 1 MeV Potassium Iion Bombardment of Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Molvik, A; Covo, M K; Bieniosek, F; Prost, L; Seidl, P; Baca, D; Coorey, A; Sakumi, A

    2004-03-25

    Gas desorption and electron emission coefficients were measured for 1 MeV potassium ions incident on stainless steel at grazing angles (between 80 and 88 degrees from normal incidence) using a new gas-electron source diagnostic (GESD). Issues addressed in design and commissioning of the GESD include effects from backscattering of ions at the surface, space-charge limited emission current, and reproducibility of desorption measurements. We find that electron emission coefficients {gamma}{sub e} scale as 1/cos({theta}) up to angles of 86 degrees, where {gamma}{sub e} = 90. Nearer grazing incidence, {gamma}{sub e} is reduced below the 1/cos({theta}) scaling by nuclear scattering of ions through large angles, reaching {gamma}{sub e} = 135 at 88 degrees. Electrons were emitted with a measured temperature of {approx}30 eV. Gas desorption coefficients {gamma}{sub 0} were much larger, of order {gamma}{sub 0} = 10{sub 4}. They also varied with angle, but much more slowly than 1/cos({theta}). From this we conclude that the desorption was not entirely from adsorbed layers of gas on the surface. Two mitigation techniques were investigated: rough surfaces reduced electron emission by a factor of ten and gas desorption by a factor of two; a mild bake to {approx}220 degrees had no effect on electron emission, but decreased gas desorption by 15% near grazing incidence. We propose that gas desorption is due to electronic sputtering.

  19. Structural basis for KCNE3 modulation of potassium recycling in epithelia

    Science.gov (United States)

    Kroncke, Brett M.; Van Horn, Wade D.; Smith, Jarrod; Kang, CongBao; Welch, Richard C.; Song, Yuanli; Nannemann, David P.; Taylor, Keenan C.; Sisco, Nicholas J.; George, Alfred L.; Meiler, Jens; Vanoye, Carlos G.; Sanders, Charles R.

    2016-01-01

    The single-span membrane protein KCNE3 modulates a variety of voltage-gated ion channels in diverse biological contexts. In epithelial cells, KCNE3 regulates the function of the KCNQ1 potassium ion (K+) channel to enable K+ recycling coupled to transepithelial chloride ion (Cl−) secretion, a physiologically critical cellular transport process in various organs and whose malfunction causes diseases, such as cystic fibrosis (CF), cholera, and pulmonary edema. Structural, computational, biochemical, and electrophysiological studies lead to an atomically explicit integrative structural model of the KCNE3-KCNQ1 complex that explains how KCNE3 induces the constitutive activation of KCNQ1 channel activity, a crucial component in K+ recycling. Central to this mechanism are direct interactions of KCNE3 residues at both ends of its transmembrane domain with residues on the intra- and extracellular ends of the KCNQ1 voltage-sensing domain S4 helix. These interactions appear to stabilize the activated “up” state configuration of S4, a prerequisite for full opening of the KCNQ1 channel gate. In addition, the integrative structural model was used to guide electrophysiological studies that illuminate the molecular basis for how estrogen exacerbates CF lung disease in female patients, a phenomenon known as the “CF gender gap.” PMID:27626070

  20. Preparation and Crystal Structure of 5-Azido-3-nitro-1H-1,2,4-triazole, Its Methyl Derivative and Potassium Salt

    Directory of Open Access Journals (Sweden)

    Thomas M. Klapötke

    2012-04-01

    Full Text Available 5-Azido-3-nitro-1H-1,2,4-triazole, its methyl derivative and potassium salt were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. The interactions between the molecules or ions were analyzed and discussed. Furthermore, all compounds were tested according to BAM (Bundesanstalt für Materialforschung und -prüfung methods.

  1. Exchange variation of hyperfine characteristics of tetrameric [Mn 3(III)Mn(IV)] and [Mn 3(IV)Mn(III)] clusters

    Science.gov (United States)

    Belinskii, M. I.

    1994-12-01

    The dependences of the cluster g-factor, the effective hyperfine constants Ai and the hyperfine structure of the EPR signal on the exchange interaction were studied for the [Mn 3(III)Mn(IV)] and [Mn 3(IV)Mn(III)] clusters - possible prototypes of the Mn center of Photosystem II in the S 2 state. The mixing of the states with different S12 intermediate spins in the Heisenberg model HB = -2[ J12s1s2 + Jα( s1s3 + s1s4) + Jβ( s2s3 + s2s4) + J34s3s4] leads to essential exchange modification of the expectation values for each manganese ion. The exchange dependence of the Ki = / coefficients results in the exchange modification and reduction of the cluster g-factor. The / variations control also the values and signs of the effective hyperfine constants Ai. The Ai( Jtm) exchange dependences for the S = 1/2 ground state of the [Mn 3(III)Mn(IV)] and [Mn 3(IV)Mn(III)] clusters with complex structures were obtained in the framework of the general Heisenberg model of tetramer. The calculated hyperfine structures show a strong dependence on the total spin, intermediate spins and on the variation of the Heisenberg exchange parameters.

  2. The Arabidopsis guard cell outward potassium channel GORK is regulated by CPK33.

    Science.gov (United States)

    Corratgé-Faillie, Claire; Ronzier, Elsa; Sanchez, Frédéric; Prado, Karine; Kim, Jeong-Hyeon; Lanciano, Sophie; Leonhardt, Nathalie; Lacombe, Benoît; Xiong, Tou Cheu

    2017-07-01

    A complex signaling network involving voltage-gated potassium channels from the Shaker family contributes to the regulation of stomatal aperture. Several kinases and phosphatases have been shown to be crucial for ABA-dependent regulation of the ion transporters. To date, the Ca2+ -dependent regulation of Shaker channels by Ca2+ -dependent protein kinases (CPKs) is still elusive. A functional screen in Xenopus oocytes was launched to identify such CPKs able to regulate the three main guard cell Shaker channels KAT1, KAT2, and GORK. Seven guard cell CPKs were tested and multiple CPK/Shaker couples were identified. Further work on CPK33 indicates that GORK activity is enhanced by CPK33 and unaffected by a nonfunctional CPK33 (CPK33-K102M). Furthermore, Ca2+ -induced stomatal closure is impaired in two cpk33 mutant plants. © 2017 Federation of European Biochemical Societies.

  3. Spatial heterogeneity of myocardial perfusion predicts local potassium channel expression and action potential duration.

    Science.gov (United States)

    Stoll, Marion; Quentin, Michael; Molojavyi, Andrej; Thämer, Volker; Decking, Ulrich K M

    2008-02-01

    In the heart, there is not only a transmural gradient of left ventricular perfusion and action potential duration (APD), but also spatial heterogeneity within each myocardial layer, where local blood flow and energy turnover vary more than three-fold between individual regions. We analysed at high spatial resolution whether a corresponding heterogeneity also extends to ion channel gene expression and APD. In the open-chest beagle dog, left ventricular 300 microL samples of very low or high flow were identified by radioactive microspheres and expression levels determined by quantitative PCR. The distribution of epicardial APD was assessed by mapping local activation repolarization intervals (ARIs) and QT interval (QT). ERG, the potassium channel mediating IKr, and KChIP2, the interacting protein modulating Ito, were increased in Low flow (3.3- and 2.5-fold, P channel expression and APD. Whenever this newly recognized intramural dispersion of APD increases, it may contribute to arrhythmogenesis.

  4. Effect of palytoxin on the sodium-potassium pump: model and simulation.

    Science.gov (United States)

    Rodrigues, Antônio M; Almeida, Antônio-Carlos G; Infantosi, Antonio F C

    2008-07-29

    We propose a reaction model for the palytoxin-sodium-potassium (PTX-Na(+)/K(+)) pump complex. The model, which is similar to the Albers-Post model for Na(+)/K(+)-ATPase, is used to elucidate the effect of PTX on Na(+)/K(+)-ATPase during the enzyme interactions with Na(+) and/or K(+) ions. Conformational substates and reactions for the pump are incorporated into the Albers-Post model to represent enzymes with or without bound PTX. A mathematical model based on the reaction scheme is used in simulations modeling experimental studies of PTX-induced ionic currents. Our simulations suggest that (i) extracellular Na(+) as well as K(+) promotes PTX-induced channel blockage; (ii) extracellular K(+) accelerates PTX unbinding; and (iii) K(+) occlusion in the PTX-pump complex is essential for describing the PTX-induced current dynamics.

  5. Combustion aerosols from potassium-containing fuels

    Energy Technology Data Exchange (ETDEWEB)

    Balzer Nielsen, Lars

    1998-12-31

    The scope of the work presented in this thesis is the formation and evolution of aerosol particles in the submicron range during combustion processes, in particular where biomass is used alone or co-fired with coal. An introduction to the formation processes of fly ash in general and submicron aerosol in particular during combustion is presented, along with some known problems related to combustion of biomass for power generation. The work falls in two parts. The first is the design of a laboratory setup for investigation of homogeneous nucleation and particle dynamics at high temperature. The central unit of the setup is a laminar flow aerosol condenser (LFAC), which essentially is a 173 cm long tubular furnace with an externally cooled wall. A mathematical model is presented which describes the formation and evolution of the aerosol in the LFAC, where the rate of formation of new nuclei is calculated using the so-called classical theory. The model includes mass and energy conservation equations and an expression for the description of particle growth by diffusion. The resulting set of nonlinear second-order partial differential equations are solved numerically using the method of orthogonal collocation. The model is implemented in the FORTRAN code MONAERO. The second part of this thesis describes a comprehensive investigation of submicron aerosol formation during co-firing of coal and straw carried out at a 380 MW{sub Th} pulverized coal unit at Studstrup Power Plant, Aarhus. Three types of coal are used, and total boiler load and straw input is varied systematically. Straw contains large amounts of potassium, which is released during combustion. Submicron aerosol is sampled between the two banks of the economizer at a flue gas temperature of 350 deg. C using a novel ejector probe. The aerosol is characterized using the SMPS system and a Berner-type low pressure impactor. The chemical composition of the particles collected in the impactor is determined using

  6. The effect factors of potassium dihydrogen phosphate crystallization in aqueous solution

    Science.gov (United States)

    Zhou, Cun; Sun, Fei; Liu, Xuzhao

    2017-01-01

    The effects of cooling rate and pH on the potassium dihydrogen phosphate crystallization process were studied by means of batch crystallization process. The experiment shows that with the increase of cooling rate, the metastable zone width increase and the induction period decrease. When the pH is 3.0, the metastable zone width and induction period are both the minimum, while the crystallization rate is the highest. The crystallization products were characterized by scanning election microscope. Potassium Dihydrogen Phosphate (KDP) is a kind of excellent nonlinear optical materials, and belongs to tetragonal system, and ideal shape is aggregate of tetragonal prism and tetragonal dipyramid, the (100) cone is alternating accumulation by double positive ions and double negative ions [1-4]. The crystals of aqueous solution method to grow have large electro-optical nonlinear coefficient and high loser-damaged threshold, and it is the only nonlinear optical crystal could be used in inertial confinement fusion (ICF), KDP crystals are the ideal system to study the native defects of complex oxide insulating material [5-7]. With the development of photovoltaic technology, KDP crystals growth and performance have become a research focus worldwide [8, 9]. The merits of the crystallization process directly affect the quality of KDP products, so the study of the effect of crystallization conditions has an important significance on industrial production. This paper studied the change rule of metastable zone width, induction period, crystallization rate and particle size distribution in crystal process, and discussed the technical condition of KDP crystallization.

  7. Differential effect of brief electrical stimulation on voltage-gated potassium channels.

    Science.gov (United States)

    Cameron, Morven A; Al Abed, Amr; Buskila, Yossi; Dokos, Socrates; Lovell, Nigel H; Morley, John W

    2017-05-01

    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 (Na V channels) that leads to action potential generation. However, several other types of voltage-gated channels are expressed that also respond to electrical stimulation. In this study, we examine the response of voltage-gated potassium channels (K V channels) to brief electrical stimulation by whole cell patch-clamp electrophysiology and computational modeling. We show that nonspiking amacrine neurons of the retina exhibit a large variety of responses to stimulation, driven by different K V -channel subtypes. Computational modeling reveals substantial differences in the response of specific K V -channel subtypes that is dependent on channel kinetics. This suggests that the expression levels of different K V -channel subtypes in retinal neurons are a crucial predictor of the response that can be obtained. These data expand our knowledge of the mechanisms of neuronal activation and suggest that K V -channel expression is an important determinant of the sensitivity of neurons to electrical stimulation. NEW & NOTEWORTHY This paper describes the response of various voltage-gated potassium channels (K V channels) to brief electrical stimulation, such as is applied during prosthetic electrical stimulation. We show that the pattern of response greatly varies between K V channel subtypes depending on activation and inactivation kinetics of each channel. Our data suggest that problems encountered when artificially stimulating neurons such as cessation in firing at high frequencies, or

  8. Urinary potassium to urinary potassium plus sodium ratio can accurately identify hypovolemia in nephrotic syndrome: a provisional study.

    Science.gov (United States)

    Keenswijk, Werner; Ilias, Mohamad Ikram; Raes, Ann; Donckerwolcke, Raymond; Walle, Johan Vande

    2018-01-01

    There is evidence pointing to a decrease of the glomerular filtration rate (GFR) in a subgroup of nephrotic children, likely secondary to hypovolemia. The aim of this study is to validate the use of urinary potassium to the sum of potassium plus sodium ratio (UK/UK+UNa) as an indicator of hypovolemia in nephrotic syndrome, enabling detection of those patients who will benefit from albumin infusion. We prospectively studied 44 nephrotic children and compared different parameters to a control group (36 children). Renal perfusion and glomerular permeability were assessed by measuring clearance of para-aminohippurate and inulin. Vaso-active hormones and urinary sodium and potassium were also measured. Subjects were grouped into low, normal, and high GFR groups. In the low GFR group, significantly lower renal plasma flow (p = 0.01), filtration fraction (p = 0.01), and higher UK/UK+UNa (p = 0.03) ratio were noted. In addition, non-significant higher plasma renin activity (p = 0.11) and aldosteron (p = 0.09) were also seen in the low GFR group. A subgroup of patients in nephrotic syndrome has a decrease in glomerular filtration, apparently related to hypovolemia which likely can be detected by a urinary potassium to potassium plus sodium ratio > 0.5-0.6 suggesting benefit of albumin infusion in this subgroup. What is Known: • Volume status can be difficult to assess based on clinical parameters in nephrotic syndrome, and albumin infusion can be associated with development of pulmonary edema and fluid overload in these patients. What is New: • Urinary potassium to the sum of urinary potassium plus sodium ratio can accurately detect hypovolemia in nephrotic syndrome and thus identify those children who would probably respond to albumin infusion.

  9. Exchange variation of hyperfine characteristics of tetrameric (Mn3(III)Mn(IV) and (Mn3(IV)Mn(III)) clusters

    Science.gov (United States)

    Belinskii, M. I.

    1994-12-01

    The dependences of the cluster g-factor, the effective hyperfine constants A(sub i) and the hyperfine structure of the EPR signal on the exchange interaction were studied for the (Mn3(III)Mn(IV) and (Mn3(IV)Mn(III)) clusters - possible prototypes of the Mn center of Photosystem II in the S2 state. The mixing of the states with different S12 intermediate spins in the Heisenberg model H(sub B) = -2(J12 s1 s2 J-alpha(s1 s3 + s1 s4) + J-beta(s2 s3 + s2 s4) + J34 s3 s4) leads to essential exchange modification of the expectation values the average value of s(sub iz) for each manganese ion. The exchange dependence of the K(sub i) = the average value of s(sub iz)/the average value of S(sub Z) coefficients results in the exchange modification and reduction of the cluster g-factor. The average value of s(sub iz)/the average value of S(sub Z) variations control also the values and signs of the effective hyperfine constants A(sub i). The A(sub i)J(sub lm) exchange dependences for the S = 1/2 ground state of the (Mn2(III)Mn(IV) and (Mn3(IV)Mn(III)) clusters with complex structures were obtained in the framework of the general Heisenberg model of tetramer. The calculated hyperfine structures show a strong dependence on the total spin, intermediate spins and on the variation of the Heisenberg exchange parameters.

  10. Soil salinity and yield of mango fertigated with potassium sources

    Directory of Open Access Journals (Sweden)

    Marcio A. Carneiro

    Full Text Available ABSTRACT Irrigated fruit crops have an important role in the economic and social aspects in the region of the Sub-middle São Francisco River Valley. Thus, the aim of this study was to evaluate soil salinity and the productive aspects of the mango crop, cv. Tommy Atkins, fertigated with doses of potassium chloride (KCl and potassium sulfate (K2SO4 during two crop cycles (from January to March 2014 and from January to March 2015. The experiment was carried out in a strip-split-plot design and five potassium doses (50, 75, 100, 125 and 150% of the recommended dose as plots and two potassium sources (KCl and K2SO4 as subplots, with four replicates. Soil electrical conductivity (EC, exchangeable sodium (Na+ and potassium (K+ contents and pH were evaluated. In addition, the number of commercial fruits and yield were determined. The fertilization with KCl resulted in higher soil EC compared with K2SO4 fertigation. Soil Na+ and K+ contents increased with increasing doses of fertilizers. K2SO4 was more efficient for the production per plant and yield than KCl. Thus, under the conditions of this study, the K2SO4 dose of 174.24 g plant-1 (24.89 kg ha-1 or 96.8% of recommendation, spacing of 10 x 7 m was recommended for a yield of 23.1 t ha-1 of mango fruits, cv. Tommy Atkins.

  11. Solid state green synthesis and catalytic activity of CuO nanorods in thermal decomposition of potassium periodate

    Science.gov (United States)

    Patel, Vinay Kumar; Bhattacharya, Shantanu

    2017-09-01

    The present study reports a facile solid state green synthesis process using the leaf extracts of Hibiscus rosa-sinensis to synthesize CuO nanorods with average diameters of 15-20 nm and lengths up to 100 nm. The as-synthesized CuO nanorods were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and selected area electron diffraction. The formation mechanism of CuO nanorods has been explained by involving the individual role of amide I (amino groups) and carboxylate groups under excess hydroxyl ions released from NaOH. The catalytic activity of CuO nanorods in thermal decomposition of potassium periodate microparticles (µ-KIO4) microparticles was studied by thermo gravimetric analysis measurement. The original size (~100 µm) of commercially procured potassium periodate was reduced to microscale length scale to about one-tenth by PEG200 assisted emulsion process. The CuO nanorods prepared by solid state green route were found to catalyze the thermal decomposition of µ-KIO4 with a reduction of 18 °C in the final thermal decomposition temperature of potassium periodate.

  12. Salinity stress induced alterations in antioxidant metabolism and nitrogen assimilation in wheat (Triticum aestivum L) as influenced by potassium supplementation.

    Science.gov (United States)

    Ahanger, Mohammad Abass; Agarwal, R M

    2017-06-01

    Experiments were conducted on two wheat (Triticum aestivum L) cultivars exposed to NaCl stress with and without potassium (K) supplementation. Salt stress induced using NaCl caused oxidative stress resulting into enhancement in lipid peroxidation and altered growth as well as yield. Added potassium led to significant improvement in growth having positive effects on the attributes including nitrogen and antioxidant metabolism. NaCl-induced stress triggered the antioxidant defence system nevertheless, the activity of antioxidant enzymes and the content of non-enzymatic antioxidants increased in K fed plants. Enhancement in the accumulation of osmolytes comprising free proline, sugars and amino acids was observed at both the developmental stages with K supplementation associated with improvement of the relative water content and ultimately yield. Potassium significantly increased uptake and assimilation of nitrogen with concomitant reduction in the Na ions and consequently Na/K ratio. Optimal K can be used as a potential tool for alleviating NaCl stress in wheat to some extent. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  13. Interactive effects of salinity and low potassium on growth, physiology response of Houttuynia cordata Thunb. W01-100

    Directory of Open Access Journals (Sweden)

    Zou Y. T.

    2012-11-01

    Full Text Available Houttuynia cordata Thunb. is a plant enrichment in potassium in plant was reported. Salinity and low potassium availability are important environmental factors restricting plant growth and productivity throughout the world. The interactive effects of salinity and potassium on growth, water content, chlorophyll content, lipid peroxidation content, ion accumulations and K+/Na+ ratio, and organic accumulations as well as oxidative enzymes were investigated in Houttuynia cordata Thunb.. Plants of three-leaf-stage were selected for uniformity, then treated with four levels of Na+ (50, 100, 200 mmol/L and K+(0, 0.6, 1.2, 2.4 mmol/L for 20 days. Plant biomass production, ratio of root and shoot, root numbers, water content and MDA content significantly declined in the combined effect of salinity and K+ deprivation, and increased with salinity. However, salinity in conjunction with K+ deprivation led to an increase on leaf chlorophyll content, which even increased with increasing salinity levels. As expected, K+ content in plant was positive correlated with supplementary K+ concentrations, while Na+ was well correlated with salinity, especially enhanced by the interactive effects of salinity and K+ deprivation. Soluble sugar and proline contents remarkable increased by the highest salinity. SOD activity also substantial increased by the highest salinity, and increased with supplementary K+ concentrations. However, elevated CAT and POD activities were not accompanied with an increase in SOD activity.

  14. A light-driven sodium ion pump in marine bacteria.

    Science.gov (United States)

    Inoue, Keiichi; Ono, Hikaru; Abe-Yoshizumi, Rei; Yoshizawa, Susumu; Ito, Hiroyasu; Kogure, Kazuhiro; Kandori, Hideki

    2013-01-01

    Light-driven proton-pumping rhodopsins are widely distributed in many microorganisms. They convert sunlight energy into proton gradients that serve as energy source of the cell. Here we report a new functional class of a microbial rhodopsin, a light-driven sodium ion pump. We discover that the marine flavobacterium Krokinobacter eikastus possesses two rhodopsins, the first, KR1, being a prototypical proton pump, while the second, KR2, pumps sodium ions outward. Rhodopsin KR2 can also pump lithium ions, but converts to a proton pump when presented with potassium chloride or salts of larger cations. These data indicate that KR2 is a compatible sodium ion-proton pump, and spectroscopic analysis showed it binds sodium ions in its extracellular domain. These findings suggest that light-driven sodium pumps may be as important in situ as their proton-pumping counterparts.

  15. Determinants of renal potassium excretion in critically ill patients: the role of insulin therapy.

    Science.gov (United States)

    Hoekstra, Miriam; Yeh, Lu; Lansink, Annemieke Oude; Vogelzang, Mathijs; Stegeman, Coen A; Rodgers, Michael G G; van der Horst, Iwan C C; Wietasch, Götz; Zijlstra, Felix; Nijsten, Maarten W N

    2012-03-01

    Insulin administration lowers plasma potassium concentration by augmenting intracellular uptake of potassium. The effect of insulin administration on renal potassium excretion is unclear. Some studies suggest that insulin has an antikaliuretic effect although plasma potassium levels were poorly controlled. Since the introduction of glycemic control in the intensive care unit, insulin use has increased. We examined the relation between administered insulin and renal potassium excretion in critically ill patients under computer-assisted glucose and potassium regulation. Prospective observational study. Twelve-bed surgical intensive care unit of a university teaching hospital. Consecutive intensive care unit patients. Potassium and glucose levels were regulated by a computer-assisted decision support system. Both potassium and insulin were continuously administered by syringe pump. Renal potassium excretion was measured daily in the 24-hr urine collections. The 24-hr urinary samples of patients with kidney failure or on renal replacement therapy were excluded. Multivariate analysis with potassium excretion as the dependent variable was performed. In 178 consecutive patients, 1,456 24-hr urinary samples, were analyzed. Mean ± SD plasma potassium was 4.2 ± 0.3 mmol/L, with 79 ± 46 mmol/d of potassium administered and a mean insulin dose of 53 ± 38 U/day. Renal potassium excretion was 126 ± 51 mmol/day. After multivariate analysis correcting for relevant variables (including diuretics, pH, potassium levels and renal sodium excretion), insulin administration was independently and positively associated with renal potassium excretion. Other significant variables were potassium levels, potassium administration, renal sodium and chloride excretion, creatinine clearance, diuretic therapy, pH, known diabetes and intensive care unit admission day (R = .52; p <. 001). Insulin administration is associated with an increase in the renal potassium excretion in critically ill

  16. Ion Exchange Properties of Georgian Natural Zeolites

    Directory of Open Access Journals (Sweden)

    Vladimer Tsitsishvili

    2017-06-01

    Full Text Available Ion-exchange properties of natural zeolites of Georgia with a relatively low Si/Al ratio have been studied: analcimes are characterized by selectivity series: Na+>K+>Ag+>NH4+>Ca+2>Sr+2>Li+; for phillipsites selectivity sequences are different for calcium- and potassium forms; selectivity sequence for scolecite is: Sr+2>Ba+2>Rb+>Ca+2>Cs+>K+>NH4+>Na+>Mg+2>Li+>Cd+2>Cu+2> Mn+2> Zn+2>Co+2>Ni+2.

  17. Potassium [(1S-1-azido-2-phenylethyl]trifluoridoborate

    Directory of Open Access Journals (Sweden)

    Tore Lejon

    2012-08-01

    Full Text Available The title compound, K+·C8H8BF3N3−, is a salt containing the chiral organic trifluoridoborate anion. The organic anions and potassium cations are tightly bound to each other by the coordination K—F [2.654 (3–3.102 (3 Å] and K—N [2.951 (4–3.338 (4 Å] interactions. Thus, the potassium cation adopts a nine-vertex coordination polyhedron, which can be described as a distorted monocapped tetragonal antiprism. In the crystal, the organic anions and potassium cations form layers parallel to (001. Weak C—H...π interactions between neighbouring phenyl rings further stabilize the crystal.

  18. Influence of potassium loading at different reaction temperatures on the NOx reduction process by potassium-containing coal pellets

    Energy Technology Data Exchange (ETDEWEB)

    Agustin Bueno-Lopez; Avelina Garcia-Garcia; Jose Antonio Caballero; A. Linares-Solano [Universidad de Alicante, Alicante (Spain). Departamento de Quimica Inorganica

    2003-02-01

    The activity of potassium-containing coal pellets and the corresponding free-metal char for NOx reduction in an oxygen-rich environment has been investigated by temperature-programmed reactions (TPRs) up to 750{sup o}C, 2 h isothermal reactions in the range of 250 475{sup o}C and lifetime tests, (until the samples were completely consumed), for selected samples and temperatures. An interesting 'reactivity window', where NOx reduction is observed, but carbon conversion is negligible, was found from TPRs experiment for a high potassium content sample, at moderate temperatures. This interval was not observed for the char. The catalytic effect of potassium is more dramatic at high temperatures, therefore, metal loading and reaction temperature are very much interrelated. Lifetime tests provide a very valuable information (average selectivity, profitable use of samples for NOx reduction, etc.), allowing us to check the whole efficiency of the samples. The progressive addition of potassium to the pellets makes samples more effective in terms of: (i) capacity to reduce higher NOx amounts; (ii) maximum NOx conversion values and (iii) higher values of average selectivity. In general, the samples studied, exhibit a maximum temperature, very much dependent on their potassium contents, that must not be exceeded with a view to practical applications. 24 refs., 6 figs., 2 tabs.

  19. Test Requirements and Conceptual Design for a Potassium Test Loop to Support an Advanced Potassium Rankine Cycle Power Conversion Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yoder, JR.G.L.

    2006-03-08

    Parameters for continuing the design and specification of an experimental potassium test loop are identified in this report. Design and construction of a potassium test loop is part of the Phase II effort of the project ''Technology Development Program for an Advanced Potassium Rankine Power Conversion System''. This program is supported by the National Aeronautics and Space Administration. Design features for the potassium test loop and its instrumentation system, specific test articles, and engineered barriers for ensuring worker safety and protection of the environment are described along with safety and environmental protection requirements to be used during the design process. Information presented in the first portion of this report formed the basis to initiate the design phase of the program; however, the report is a living document that can be changed as necessary during the design process, reflecting modifications as additional design details are developed. Some portions of the report have parameters identified as ''to be determined'' (TBD), reflecting the early stage of the overall process. In cases where specific design values are presently unknown, the report attempts to document the quantities that remain to be defined in order to complete the design of the potassium test loop and supporting equipment.

  20. The relationship between serum potassium, potassium variability and in-hospital mortality in critically ill patients and a before-after analysis on the impact of computer-assisted potassium control.

    Science.gov (United States)

    Hessels, Lara; Hoekstra, Miriam; Mijzen, Lisa J; Vogelzang, Mathijs; Dieperink, Wim; Lansink, Annemieke Oude; Nijsten, Maarten W

    2015-01-06

    The relationship between potassium regulation and outcome is not known. Our first aim in the present study was to determine the relationship between potassium level and variability in (ICU) stay and outcome. The second aim was to evaluate the impact of a computer-assisted potassium regulation protocol. We performed a retrospective before-after study including all patients >15 years of age admitted for more than 24 hours to the ICU of our university teaching hospital between 2002 and 2011. Potassium control was fully integrated with computerized glucose control (glucose and potassium regulation program for intensive care patients (GRIP-II)). The potassium metrics that we determined included mean potassium, potassium variability (defined as the standard deviation of all potassium levels) and percentage of ICU time below and above the reference range (3.5 through 5.0 mmol/L). These metrics were determined for the first ICU day (early phase) and the subsequent ICU days (late phase; that is, day 2 to day 7). We also compared potassium metrics and in-hospital mortality before and after GRIP-II was implemented in 2006. Of all 22,347 ICU admissions, 10,451 (47%) patients were included. A total of 206,987 potassium measurements were performed in these patients. Glucose was regulated by GRIP-II in 4,664 (45%) patients. The overall in-hospital mortality was 22%. There was a U-shaped relationship between the potassium level and in-hospital mortality (P <0.001). Moreover, potassium variability was independently associated with outcome. After implementation of GRIP-II, in the late phase the time below 3.5 mmol/L decreased from 9.2% to 3.9% and the time above 5.0 mmol/L decreased from 6.1% to 5.2%, and potassium variability decreased from 0.31 to 0.26 mmol/L (all P <0.001). The overall decrease in in-hospital mortality from 23.3% before introduction of GRIP-II to 19.9% afterward (P <0.001) was not related to a specific potassium subgroup. Hypokalemia, hyperkalemia and

  1. Sodium and potassium lidar system and preliminary result in Brazil

    Science.gov (United States)

    Du, Lifang

    2017-04-01

    This paper reported that the first sodium and potassium lidar was built at November, 2016 in INPE(S23°,W45°) by National Space Science Center, Chinese Academy of Sciences. This system first time realized the potassium and sodium metal layer at the same time above the detection In South America. The lidar system use a powerful pulse YAG laser to pumped two dye lasers at the same time, and join the advanced technology, such as narrow line-width grating technique, efficient laser frequency doubling technique, wavelength automatic locking technique and the double optical fiber in the focal plane for spectra separation technique and so on, which made the 589 nm and 770 nm laser line width to achieve 0.03cm-1 and the laser frequency doubling efficiency to reached above 65%. In this way, the simultaneously detecting the atmosphere at the altitude of 80 110 km by sodium and potassium fluorescence in one lidar facility has been realized. On November 20, 2016, this system began to observation for the first time in Brazil, and it has the detection data of South America about potassium and sodium at the same time. Observed data show that sodium echo photon counting rate is higher than 31874count/160s/96m, potassium echo photon counting rate is higher than 2153count/320s/96m. Comparing with both of at home or abroad, the results are a very good. In particular, the detection results level of potassium take the leading position in the international.

  2. Alkali activated fly ash binders. A comparative study between sodium and potassium activators

    Directory of Open Access Journals (Sweden)

    Criado, M.

    2006-03-01

    Full Text Available This paper shows the effect of the nature of some alkaline activators in the microstructural development of thermal-alkali activated f/y ash systems. The alkaline compounds employed in this investigation were: NaOH, KOH, Na2C03, K2C03, sodium silicate and potassium silicate. Results confirm that the main reaction product of the activation process (throughout the studied systems is the amorphous alkaline aluminosilicate gel with a three-dimensional structure already observed in earlier research. It has been proved that the type of anion and cation involved in the activation reaction of the ashes not only affects the microstructural development of the systems but the Si/Al ratio of that prezeolitic gel too. For example, in the presence of soluble silicate ions the content of Si in the final structure is notably increased (Si/Al =2.7-3.0, however carbonate ions play a different role since the formation of Sodium or Potassium carbonate/bicarbonate acidifies the system and consequently the reaction rate is considerably slowed. Finally it is evident that; when all experimental conditions are equal, sodium has a greater capacity than potassium to accelerate the setting and hardening reactions of fly ash and also to stimulate the growth of certain zeolitic crystals (reaction by-products. In general it can be affirmed that OH- ion acts as a reaction catalyst; and the alkaline metal (M+ acts as a structure-forming element.Este trabajo muestra el efecto de la naturaleza del activador alcalino en el desarrollo microestructural de sistemas de ceniza volante, activados térmica y alcalinamente. Los componentes alcalinos empleados en esta investigación fueron: NaOH, KOH, Na2C03, K2C03, silicato sódico y silicato potásico. Los resultados obtenidos confirman que el principal producto de reacción del proceso de activación (a través de los sistemas estudiados es un gel de aluminosilicato alcalino amorfo con estructura tridimensional ya observada en trabajos

  3. Preparation and Aromatic Hydrocarbon Removal Performance of Potassium Ferrate

    Directory of Open Access Journals (Sweden)

    Wei Guan

    2014-01-01

    Full Text Available This experiment adopts the hypochlorite oxidation method to constantly synthesize potassium ferrate. Under the condition of micropolluted source water pH and on the basis of naphthalene, phenanthrene, and pyrene as research objects, the effects of different systems to remove aromatic hydrocarbons were studied. Various oxidation systems to remove phenanthrene intermediate are analyzed and the detailed mechanisms for removal of phenanthrene are discussed. The study found that the main intermediate of potassium ferrate system to transform phenanthrene is 9,10-phenanthraquinone and its area percentage reached 82.66%; that is, 9,10-phenanthraquinone is the key entity to remove phenanthrene.

  4. [Quantitative determination of penicillins by iodometry using potassium hydrogen peroxymonosulfate].

    Science.gov (United States)

    Blazhevskiĭ, N E; Karpova, S P; Kabachyĭ, V I

    2013-01-01

    The kinetics and stoichiometry of S-oxidation of semisynthetic penicillins (amoxicillin trihydrate, ampicillin trihydrate, sodium salt of oxacillin and ticarcillin disodium salt) by potassium hydrogen peroxymonosulfate in aqueous solutions at pH 3-6 was studied by iodometric titration: 1 mol of KNSO5 per 1 mol of penicillin, the quantitative interaction is achieved in 1 min (time of observation). A unified method was developed and the possibility of quantification of penicillins by the iodometric method using potassium hydrogen peroxymonosulfate as an analytical reagent was shown.

  5. Effet Du Potassium Et Du Deficit Hydrique Modere Sur La ...

    African Journals Online (AJOL)

    Le comportement de 6 génotypes de cette plante, sous deux régimes hydriques, avec ou sans apport de potassium, a été suivi dans des tubes en PVC. Le potassium a été apporté sous forme de KCl ou de K2SO4. Il n\\'y a pas de différence entre les effets du KCl et du K2SO4 sur la transpiration par mg de feuilles sèches ...

  6. Superconductivity in potassium-doped few-layer graphene.

    Science.gov (United States)

    Xue, Mianqi; Chen, Genfu; Yang, Huaixin; Zhu, Yuanhua; Wang, Duming; He, Junbao; Cao, Tingbing

    2012-04-18

    Here we report the successful synthesis of superconducting potassium-doped few-layer graphene (K-doped FLG) with a transition temperature of 4.5 K, which is 1 order of magnitude higher than that observed in the bulk potassium graphite intercalation compound (GIC) KC(8) (T(c) = 0.39 K). The realization of superconductivity in K-doped FLG shows the potential for the development of new superconducting electronic devices using two-dimensional (2D) graphene as a basis material. © 2012 American Chemical Society

  7. Potassium Permanganate as an Alternative for Gold Mining Wastewater Treatment

    Science.gov (United States)

    Ordiales, M.; Fernández, D.; Verdeja, L. F.; Sancho, J.

    2015-09-01

    The feasibility of using potassium permanganate as a reagent for cyanide oxidation in wastewater was experimentally studied. Both artificial and production wastewater from two different gold mines were tested. The experiments had three goals: determine the optimum reagent concentration and reaction time required to achieve total cyanide removal, obtain knowledge of the reaction kinetics, and improve the management of the amount of reagent. The results indicate that potassium permanganate is an effective and reliable oxidizing agent for the removal of cyanide from gold mining wastewater.

  8. Noise controlled synchronization in potassium coupled neural models

    DEFF Research Database (Denmark)

    Postnov, Dmitry E; Ryazanova, Ludmila S; Zhirin, Roman A

    2007-01-01

    The paper applies biologically plausible models to investigate how noise input to small ensembles of neurons, coupled via the extracellular potassium concentration, can influence their firing patterns. Using the noise intensity and the volume of the extracellular space as control parameters, we...... show that potassium induced depolarization underlies the formation of noise-induced patterns such as delayed firing and synchronization. These phenomena are associated with the appearance of new time scales in the distribution of interspike intervals that may be significant for the spatio...

  9. Changes in plasma potassium concentration during carbon dioxide pneumoperitoneum

    DEFF Research Database (Denmark)

    Perner, A; Bugge, K; Lyng, K M

    1999-01-01

    Hyperkalaemia with ECG changes had been noted during prolonged carbon dioxide pneumoperitoneum in pigs. We have compared plasma potassium concentrations during surgery in 11 patients allocated randomly to undergo either laparoscopic or open appendectomy and in another 17 patients allocated randomly...... to either carbon dioxide pneumoperitoneum or abdominal wall lifting for laparoscopic colectomy. Despite an increasing metabolic acidosis, prolonged carbon dioxide pneumoperitoneum resulted in only a slight increase in plasma potassium concentrations, which was both statistically and clinically insignificant....... Thus hyperkalaemia is unlikely to develop in patients with normal renal function undergoing carbon dioxide pneumoperitoneum for laparoscopic surgery....

  10. Incorporating Born solvation energy into the three-dimensional Poisson-Nernst-Planck model to study ion selectivity in KcsA K+ channels

    Science.gov (United States)

    Liu, Xuejiao; Lu, Benzhuo

    2017-12-01

    Potassium channels are much more permeable to potassium than sodium ions, although potassium ions are larger and both carry the same positive charge. This puzzle cannot be solved based on the traditional Poisson-Nernst-Planck (PNP) theory of electrodiffusion because the PNP model treats all ions as point charges, does not incorporate ion size information, and therefore cannot discriminate potassium from sodium ions. The PNP model can qualitatively capture some macroscopic properties of certain channel systems such as current-voltage characteristics, conductance rectification, and inverse membrane potential. However, the traditional PNP model is a continuum mean-field model and has no or underestimates the discrete ion effects, in particular the ion solvation or self-energy (which can be described by Born model). It is known that the dehydration effect (closely related to ion size) is crucial to selective permeation in potassium channels. Therefore, we incorporated Born solvation energy into the PNP model to account for ion hydration and dehydration effects when passing through inhomogeneous dielectric channel environments. A variational approach was adopted to derive a Born-energy-modified PNP (BPNP) model. The model was applied to study a cylindrical nanopore and a realistic KcsA channel, and three-dimensional finite element simulations were performed. The BPNP model can distinguish different ion species by ion radius and predict selectivity for K+ over Na+ in KcsA channels. Furthermore, ion current rectification in the KcsA channel was observed by both the PNP and BPNP models. The I -V curve of the BPNP model for the KcsA channel indicated an inward rectifier effect for K+ (rectification ratio of ˜3 /2 ) but indicated an outward rectifier effect for Na+ (rectification ratio of ˜1 /6 ) .

  11. Incorporating Born solvation energy into the three-dimensional Poisson-Nernst-Planck model to study ion selectivity in KcsA K^{+} channels.

    Science.gov (United States)

    Liu, Xuejiao; Lu, Benzhuo

    2017-12-01

    Potassium channels are much more permeable to potassium than sodium ions, although potassium ions are larger and both carry the same positive charge. This puzzle cannot be solved based on the traditional Poisson-Nernst-Planck (PNP) theory of electrodiffusion because the PNP model treats all ions as point charges, does not incorporate ion size information, and therefore cannot discriminate potassium from sodium ions. The PNP model can qualitatively capture some macroscopic properties of certain channel systems such as current-voltage characteristics, conductance rectification, and inverse membrane potential. However, the traditional PNP model is a continuum mean-field model and has no or underestimates the discrete ion effects, in particular the ion solvation or self-energy (which can be described by Born model). It is known that the dehydration effect (closely related to ion size) is crucial to selective permeation in potassium channels. Therefore, we incorporated Born solvation energy into the PNP model to account for ion hydration and dehydration effects when passing through inhomogeneous dielectric channel environments. A variational approach was adopted to derive a Born-energy-modified PNP (BPNP) model. The model was applied to study a cylindrical nanopore and a realistic KcsA channel, and three-dimensional finite element simulations were performed. The BPNP model can distinguish different ion species by ion radius and predict selectivity for K^{+} over Na^{+} in KcsA channels. Furthermore, ion current rectification in the KcsA channel was observed by both the PNP and BPNP models. The I-V curve of the BPNP model for the KcsA channel indicated an inward rectifier effect for K^{+} (rectification ratio of ∼3/2) but indicated an outward rectifier effect for Na^{+} (rectification ratio of ∼1/6).

  12. Environmental and energy gains from using molten magnesium–sodium–potassium chlorides for electro-metallisation of refractory metal oxides

    Directory of Open Access Journals (Sweden)

    Wei Li

    2015-12-01

    Full Text Available The molten eutectic mixture of magnesium, sodium and potassium chlorides (MgCl2–NaCl–KCl has inappreciable solubility for oxide ions, and can help disengage a carbon anode from the oxide ions generated at a metal oxide cathode, and effectively avoid carbon dioxide formation. This “disengaging strategy” was successfully demonstrated in electro-reduction of solid oxides of zirconium and tantalum. It has led to significantly higher current efficiency (93%, and lower energy consumption (1.4 kW h kg−1 in electrolysis of tantalum oxide to tantalum metal compared to the conventional electrolysis in molten calcium chloride (e.g. 78% and 2.4 kW h/kg-Ta.

  13. Chemical Speciation of Some metal ions in Groundwaters of Yola ...

    African Journals Online (AJOL)

    Michael Horsfall

    bioavailability are 95.83% to 99.84% at the pH ranges of 6.1 to 7.8 of the tested wells. Iron as free Fe2+ was bioavailable at 46.53% to 79.37% of the total iron. The lower values of free Fe2+ ions are related to the organic ... calcium, magnesium, potassium and iron in groundwater using geochemical models from the.

  14. Potassium changes in trained subjects after potassium loading and during restriction of muscular activity and chronic hyperhydration.

    Science.gov (United States)

    Zorbas, Y G; Federenko, Y F; Naexu, K A

    1996-01-01

    The objective of this investigation was to determine whether urinary and plasma potassium changes developed during prolonged hypokinesia (HK) (decreased number of km/d) in endurance-trained subjects could be minimized or reversed with a daily intake of fluid and salt supplementation (FSS). The studies were performed on 30 endurance-trained male volunteers aged 23-26 yr with an average peak oxygen uptake of 65 mL/kg min during 364 d of HK. All volunteers were on an average of 13.8 km/d prior to their exposure to HK. All volunteers were randomly divided into three groups: 10 volunteers were placed continuously under an average of 14.0 km/d (control subjects), 10 volunteers were subjected continuously to an average of 2.7 km/d (unsupplemented hypokinetic subjects), and 10 volunteers were submitted continuously to an average of 2.7 km/d, and consumed daily an additional amount of 0.1 g sodium chloride (NaCl)/kg body wt and 30 mL water/kg body wt (supplemented hypokinetic subjects). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d, potassium loading tests were performed with 1.5-1.7 mEq potassium chloride/kg body wt, and potassium, sodium, and chloride excretion in urine and potassium, sodium, and chloride in plasma were determined. In the unsupplemented hypokinetic volunteers, urinary excretion of electrolytes and concentrations of electrolytes in plasma increased significantly as compared to the control and supplemented hypokinetic groups of volunteers. It was concluded that daily intake of fluid and salt supplementation had a favorable effect on regulation of urinary and plasma potassium changes in trained subjects during prolonged HK.

  15. From lattice ion ion-exchanger to ion memorizing ion-exchanger; Koshi ion ion kokantai kara ion kioku ion kokantai e

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T. [Yamanashi University, Yamanashi (Japan). Faculty of Engineering

    1996-05-05

    Introduced in this report is the lattice-ion ion exchanger and ion-memorizing ion exchanger that have of late developed into key words. The former is the name given to inorganic ion exchangers, such as hydroxyapatite (hereinafter to be shortened to HAp), which selectively exchange ions for other ions in a water solution, at the ordinary temperature and atmospheric pressure off the common knowledge in inorganic structural chemistry. HAp is an example different from the conventional counter-ion ion exchangers as represented by zeolite, in terms of the order of selectiveness it demonstrates when encountering various cations. HAp and the same with its PO4{sup 3-} ion group replaced with a CO3{sup 2-} or SiO4{sup 4-} group is effective in removing dangerous ions and in sterilizing. The ion-memorizing ion exchanger is a development from the lattice-ion ion exchanger, and is capable of very selectively collecting and removing specified ions as if it remembered the specified ions. The Li- or K-ion-memorizing ion exchanger is a typical example. 17 refs., 4 figs, 4 tabs.

  16. Intracellular ion channels and cancer.

    Science.gov (United States)

    Leanza, Luigi; Biasutto, Lucia; Managò, Antonella; Gulbins, Erich; Zoratti, Mario; Szabò, Ildikò

    2013-09-03

    Several types of channels play a role in the maintenance of ion homeostasis in subcellular organelles including endoplasmatic reticulum, nucleus, lysosome, endosome, and mitochondria. Here we give a brief overview of the contribution of various mitochondrial and other organellar channels to cancer cell proliferation or death. Much attention is focused on channels involved in intracellular calcium signaling and on ion fluxes in the ATP-producing organelle mitochondria. Mitochondrial K(+) channels (Ca(2+)-dependent BKCa and IKCa, ATP-dependent KATP, Kv1.3, two-pore TWIK-related Acid-Sensitive K(+) channel-3 (TASK-3)), Ca(2+) uniporter MCU, Mg(2+)-permeable Mrs2, anion channels (voltage-dependent chloride channel VDAC, intracellular chloride channel CLIC) and the Permeability Transition Pore (MPTP) contribute importantly to the regulation of function in this organelle. Since mitochondria play a central role in apoptosis, modulation of their ion channels by pharmacological means may lead to death of cancer cells. The nuclear potassium channel Kv10.1 and the nuclear chloride channel CLIC4 as well as the endoplasmatic reticulum (ER)-located inositol 1,4,5-trisphosphate (IP3) receptor, the ER-located Ca(2+) depletion sensor STIM1 (stromal interaction molecule 1), a component of the store-operated Ca(2+) channel and the ER-resident TRPM8 are also mentioned. Furthermore, pharmacological tools affecting organellar channels and modulating cancer cell survival are discussed. The channels described in this review are summarized on Figure 1. Overall, the view is emerging that intracellular ion channels may represent a promising target for cancer treatment.

  17. Intracellular ion channels and cancer

    Directory of Open Access Journals (Sweden)

    Luigi eLeanza

    2013-09-01

    Full Text Available Several types of channels play a role in the maintenance of ion homeostasis in subcellular organelles including endoplasmatic reticulum, nucleus, lysosome, endosome and mitochondria. Here we give a brief overview of the contribution of various mitochondrial and other organellar channels to cancer cell proliferation or death. Much attention is focused on channels involved in intracellular calcium signaling and on ion fluxes in the ATP-producing organelle mitochondria. Mitochondrial K+ channels (Ca2+-dependent BKCa and IKCa, ATP-dependent KATP, Kv1.3, two-pore TWIK-related Acid-Sensitive K+ channel-3 (TASK-3, Ca2+ uniporter MCU, Mg2+-permeable Mrs2, anion channels (voltage-dependent chloride channel VDAC, intracellular chloride channel CLIC and the Permeability Transition Pore (MPTP contribute importantly to the regulation of function in this organelle. Since mitochondria play a central role in apoptosis, modulation of their ion channels by pharmacological means may lead to death of cancer cells. The nuclear potassium channel Kv10.1 and the nuclear chloride channel CLIC4 as well as the endoplasmatic reticulum (ER-located inositol 1,4,5-trisphosphate (IP3 receptor, the ER-located Ca2+ depletion sensor STIM1 (stromal interaction molecule 1, a component of the store-operated Ca2+ channel and the ER-resident TRPM8 are also mentioned. Furthermore, pharmacological tools affecting organellar channels and modulating cancer cell survival are discussed. The channels described in this review are summarized on Figure 1. Overall, the view is emerging that intracellular ion channels may represent a promising target for cancer treatment.

  18. The effect of some ions on the muscle fibre resting potential in the cricket Acheta domesticus.

    Science.gov (United States)

    Janiszewski, L; Olszewska, E; Borkowska, M J

    1976-01-01

    Experiments were carried out on the skeletal muscle fibres of the cricket Acheta domesticus using conventional microelectrode methods. Both potassium and ammonium ions depolarized the fibres but with a considerable divergance from the slope of 58 mV. Calcium ions hyperpolarized the fibres. High concentrations of magnesium ions or dramatic increase in the osmotic pressure of the bathing medium exerted no influence on the resting potential. It seems likely that skeletal muscle fibres of Acheta domesticus at rest are multionic electrodes, but the role played by various ions needs further studies.

  19. Development and validation of models predicting the toxicity of major seawater ions to the mysid shrimp, Americamysis bahia.

    Science.gov (United States)

    Pillard, David A; DuFresne, Doree L; Mickley, Mike C

    2002-10-01

    The concentration and balance of major ions that comprise total dissolved solids (TDS) can influence the toxicity of effluents discharged to freshwater and marine environments. An additional complicating factor in waters released to saltwater systems is the effluent salinity since the toxicity of major ions changes with the salinity of the test solution. A study was conducted to evaluate the toxicity of six major seawater ions (bicarbonate, borate, calcium, magnesium, potassium, and sulfate) to the mysid shrimp, Americamysis bahia, at salinities of 10 and 20/1000. Logistic regression models were developed to predict organism survival at deficient and excess concentrations of the ions. Calcium and potassium caused significant mortality to mysid shrimp in both excess and deficient (relative to artificial seawater) solutions. Bicarbonate, borate, and magnesium displayed significant toxicity only in excess concentrations, while sulfate had no adverse impacts at any of the concentrations tested. As the salinity of the test solutions decreased, mysid shrimp tolerated increasingly lower calcium and potassium concentrations. Similarly, as salinity increased, the upper tolerance levels of calcium, potassium, and magnesium also increased. The models developed during these studies, and similar models developed by other researchers, were used to evaluate 11 actual effluents with unexplained toxicity that might be associated with TDS ions. The models correctly identified calcium as the primary toxicant in 9 of the 11 effluents. These results indicate the models can be used as an important tool to identify toxicity associated with major seawater ions.

  20. Urinary potassium excretion, renal ammoniagenesis, and risk of graft failure and mortality in renal transplant recipients

    NARCIS (Netherlands)

    Eisenga, Michele F.; Kieneker, Lyanne M.; Soedamah-Muthu, Sabita S.; van den Berg, Else; Deetman, Petronella E.; Navis, Gerjan J.; Gans, Reinold O. B.; Gaillard, Carlo A. J. M.|info:eu-repo/dai/nl/073810339; Bakker, Stephan J. L.; Joosten, Michel M.

    2016-01-01

    Background: Renal transplant recipients (RTRs) have commonly been urged to limit their potassium intake during renal insufficiency and may adhere to this principle after transplantation. Importantly, in experimental animal models, low dietary potassium intake induces kidney injury through

  1. Palytoxin and the sodium/potassium pump--phosphorylation and potassium interaction.

    Science.gov (United States)

    Rodrigues, Antônio M; Infantosi, Antonio F C; de Almeida, Antônio-Carlos G

    2009-05-21

    We proposed a reaction model for investigating interactions between K+ and the palytoxin-sodium-potassium (PTX-Na+/K+) pump complex under conditions where enzyme phosphorylation may occur. The model is composed of (i) the Albers-Post model for Na+/K+-ATPase, describing Na+ and K+ pumping; (ii) the reaction model proposed for Na+/K+-ATPase interactions with its ligands (Na+, K+, ATP, ADP and P) and with PTX. A mathematical model derived for representing the reactions was used to simulate experimental studies of the PTX-induced current, in different concentrations for the pump ligands. The simulations allow interpretation of the simultaneous action of Na+/K+-ATPase phosphorylation and K+ on the PTX-induced channels. The results suggest that(i) phosphorylation increases the PTX toxic effect, increasing its affinity and reducing the K+occlusion rate, and (ii) K+ causes channel blockage, increases the toxin dissociation rate and impedes the induced channel phosphorylation, implying reduction of the PTX toxic effect.

  2. Potassium evaluation in blood of Brazilian athletes using NAA

    Energy Technology Data Exchange (ETDEWEB)

    Kovacs, L.; Zamboni, C.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Nunes, L.A.S.; Lourenco, T.F.; Macedo, D. Vaz de [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2010-07-01

    Full text: According to nutrition sources an athlete needs per day at least one gram of potassium for keeping the correct mineral balance in the organism. Its deficiency or even instantaneous low concentration in blood can diminish the athlete performance originating nervous irritability, muscular weakness, and mental disorientation and in more several causes cardiac arrhythmias. In this study the K levels in blood were determined in athletes submitted to constant load exercise at treadmill at LABEX (Laboratorio de Bioquimica do Exercicio - UNICAMP, Brazil) using Neutron Activation Analyses (NAA). The blood samples were collected from male athletes, age 18 to 26 years, before and after the physical training. Immediately after the collection an amount of 10 micro liters of whole blood was transferred to the filter paper and dried for a few minutes using an infrared lamp. To determine the concentration of potassium each sample was irradiated in the nuclear reactor (IEA-R1, 2-4MW, pool type) at IPEN and was gamma counted using an HPGe Spectrometer of High Energy Resolution. The concentrations of the selected element, 1525keV related to the potassium activated {sup 42}K, were calculated using in -house software. The potassium levels were evaluated before and after the physical exercise and the data were compared with the normal range. (author)

  3. Extractahility of Potassium from Some Organic Manures in Aqueous ...

    African Journals Online (AJOL)

    Fig l: (imitative Pl\\1mctittn of Native it” from Marlin: Sanples. The usually high solubility and mobility of potassium in aqueous solution is a useful property in its release phenomenon with respect to fertilizer application in crop production, but which could also be a disadvantage since its effect may be short-lived. l'lowever, it is ...

  4. Effect of potassium simplex optimization medium (KSOM) and ...

    African Journals Online (AJOL)

    In this study, we produced cloned transgenic dairy goat based on dairy goat ear skin fibroblast as donor cells for nuclear transfer (NT), which were modified by human lactoferrin (hLF) gene. The developmental competence of NT embryos was compared with either between different embryo culture medium, potassium ...

  5. Formulation and evaluation of sublingual tablets of losartan potassium

    Directory of Open Access Journals (Sweden)

    Nikunj J. Aghera

    2012-05-01

    Full Text Available Objective: Sublingual tablets of Losartan Potassium were prepared to improve its bioavailability, to avoid pre-systemic metabolism in the gastrointestinal tract and hepatic first pass elimination. Methods: The Sublingual tablets were prepared by direct compression procedure using different concentration of Starch 1500 and microcrystalline cellulose. Compatibility studies of drug and polymer were performed by FTIR spectroscopy and DSC. Preformulation property of API was evaluated. Postcompressional parameters such disintegration time, wetting time, water absorption ratio, in vitro drug release and in vivo bioavailability study of optimized formulation were determined. Results: FTIR spectroscopy and DSC study revealed that there was no possible interaction between drug and polymers. The precompression parameters were in acceptable range of pharmacopoeial specification. The disintegration time of optimized formulation (F3 was upto 48 sec. The in vitro release of Losartan Potassium was upto 15 min. The percentage relative bioavailability of Losartan Potassium from optimized sublingual tablets was found to be 144.7 %. Conclusions: Sublingual tablets of Losartan Potassium were successfully prepared with improved bioavailability.

  6. Transmission spectra study of sulfate substituted potassium dihydrogen phosphate

    KAUST Repository

    LI, LIANG

    2013-04-18

    Potassium dihydrogen phosphate (KDP) crystals with different amounts of sulfate concentration were grown and the transmittance spectrum was studied. A crystal with high sulfate replacement density exhibits heavy absorption property in the ultraviolet region which confirms and agrees well with former results. © 2013 Astro Ltd.

  7. Inhibition of large conductance calcium-dependent potassium ...

    African Journals Online (AJOL)

    We tested the hypothesis that Rho-kinase inhibits the large-conductance, calcium and voltage dependent potassium (BKCa) channels thereby promoting vasoconstriction. Our results show that the Rho-kinase inhibitor, Y-27632, induced concentration-dependent relaxation in rat mesenteric artery. The selective BKCa ...

  8. Superconductivity at 18 K in potassium-doped C60

    NARCIS (Netherlands)

    Hebard, A.F.; Rosseinsky, M.J.; Haddon, R.C.; Murphy, D.W.; Glarum, S.H.; Palstra, T.T.M.; Ramirez, A.P.; Kortan, A.R.

    1991-01-01

    The synthesis of macroscopic amounts of C60 and C70 (fullerenes) has stimulated a variety of studies on their chemical and physical properties. We recently demonstrated that C60 and C70 become conductive when doped with alkali metals. Here we describe low-temperature studies of potassium-doped C60

  9. Enhanced apparatus for AC Zeeman experiments with ultracold potassium

    Science.gov (United States)

    Rotunno, Andrew; Du, Shuangli; Fancher, Charles; Pyle, Andrew; Aubin, Seth

    2016-05-01

    Ultracold atomic potassium is an excellent candidate for studies of the AC Zeeman force, due to small hyperfine splittings. These experiments require a sufficient sample of potassium near an atom chip supporting RF currents, and an RF source which can make rapid phase-continuous frequency sweeps for fast manipulation of spin states. We present progress on the construction of laser amplifier system for improved laser cooling and trapping of potassium, development of a frequency-agile RF source, and research on RF-capable atom chips. The laser amplifier system consists of two tapered amplifiers for producing 0.4 W of 767 nm light, with a goal of collecting 107 potassium atoms at 100 μK, which will then be cooled sympathetically with ultracold rubidium. We have constructed a direct digital synthesizer (DDS) to produce 1-400 MHz with Hz-level linewidth and noise level below -60dBc, and the ability to produce fast 100 μs frequency sweeps. We are investigating atom chip designs for supporting large RF currents. Immediate applications include AC Zeeman potentials and traps for atom interferometry, and quantum many-body physics. Work supported by AFOSR, W&M, and in part by AFRL.

  10. Performance Evaluation of Refractory Composite Coatings in Potassium Rich Environment

    Directory of Open Access Journals (Sweden)

    Kristina BRINKIENĖ

    2016-09-01

    Full Text Available A laboratory scale method was used to study the performance of reinforced cement composites in potassium rich environment of biomass combustion. Buckwheat husk (BH was used as potential source of unexploited biomass product applicable as biomass derived fuel. In order to enhance the alkali effect on the properties of the investigated materials, the solution of potassium carbonate (K2CO3 was selected as potassium rich aggressive environment. Two reinforced cement composites as potential repair coatings for restoration of damaged refractory surfaces with different composition of aggregate were used in corrosion tests. Performance of refractory coatings was evaluated by analysing the microstructure of the treated composites as well as mechanical properties. Energy-dispersive X-ray spectroscopy (SEM/EDS and optical microscopy were used to study the microstructure in the corroded region of the refractory coatings. Long term studies in the solution of 1M K2CO3 for 56 months have demonstrated that composite with the additive of fluid cracking catalyst of oil refinery and petrochemical industries is more durable in the potassium rich environment.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.8348

  11. Toward a consensus model of the HERG potassium channel.

    NARCIS (Netherlands)

    Stary, A.; Wacker, S.J.; Boukharta, L.; Zachariae, U.G.; Karimi-Nejad, Y.; Aqvist, J.; Vriend, G.; Groot, B.L. de

    2010-01-01

    Malfunction of hERG potassium channels, due to inherited mutations or inhibition by drugs, can cause long QT syndrome, which can lead to life-threatening arrhythmias. A three-dimensional structure of hERG is a prerequisite to understand the molecular basis of hERG malfunction. To achieve a consensus

  12. Histopathologic effect of potassium bromate on the kidney of adult ...

    African Journals Online (AJOL)

    Objective: We aimed to demonstrate the histopathologic effects of potassium bromate (KBrO ) on the kidney tissues of rats following 3 short-term and long-term exposures. Method: Twenty young wistar rats of weights 180-250g were divided into three groups. The control group A was sub-divided into two groups of three rats ...

  13. Elevated potassium levels in patients with chronic kidney disease

    DEFF Research Database (Denmark)

    Thomsen, Reimar W; Nicolaisen, Sia K; Hasvold, Pål

    2018-01-01

    Background: Data on the true burden of hyperkalemia (HK) in patients with chronic kidney disease (CKD) in a real-world setting are scarce. Methods: The incidence rate of HK [first blood test with an elevated blood potassium level level >5.0 mmol/L] in primary or hospital care was assessed...

  14. Effect of different concentrations of potassium and magnesium on ...

    African Journals Online (AJOL)

    The rate of root colonization by mycorrhizal fungi largely depends on the concentration of nutrient elements in roots and soil. In this study, the effects of different concentrations of potassium and magnesium on mycorrhizal colonization of maize grown in pot cultures were studied. This experiment was performed using natural ...

  15. New nonabsorbable potassium-exchange resins in hyperkalaemia

    NARCIS (Netherlands)

    Roscioni, Sara S.; Lambers Heerspink, Hiddo

    New data suggest that treatment with patiromer or sodium zirconium cyclosilicate for up to 8 weeks reduces plasma potassium levels in hyperkalaemic patients. If proven safe and effective for long-term use, these therapies might be administered together with intensive renin-angiotensin-aldosterone

  16. Does Electroconvulsive therapy aggravate the rise in potassium and ...

    African Journals Online (AJOL)

    Background: Potassium and creatine kinase levels increase after the administration of suxamethonium. This rise may be exaggerated by the combination of suxamethonium fasciculation and the modified tonic/clonic convulsion induced by electroconvulsive therapy. This study compared the magnitude of increase in ...

  17. Effect of nitrogen and potassium fertilization on morpho-agronomic ...

    African Journals Online (AJOL)

    Elephant grass has been proposed for the energy sector as a possible source of renewable energy, because of its high biomass production. The aim of this study was to evaluate the effect of the mineral nutrients nitrogen and potassium on the morpho-agronomic traits (dry mater yield (DMY), percentage of DM (%DM), ...

  18. Characterization of verdete rock as a potential source of potassium

    Directory of Open Access Journals (Sweden)

    Wedisson Oliveira Santos

    2015-08-01

    Full Text Available Potassium is a nutrient found at low levels in Brazilian soils, requiring large inputs of fertilizers to achieve satisfactory crop yields. Brazil has high external dependence and limited reserves of soluble K mineral, which is traditionally exploited for the production of fertilizers. On the other hand, it is common the occurrence in the country of potassium-rich silicate minerals which are not commercially exploited. This study aimed to characterize mineralogically and chemically samples of verdete rock separated into size fractions and evaluate its potential as potassium fertilizer. The mineral composition of verdete rock is based on glauconite, quartz and feldspar. The total K2O content in verdete rock ranged from 5.18 to 9.0 dag/kg. The K content extracted in water or 2% citric acid was 2.4% below the total of K, indicating low reactivity of verdete rock and limitations for direct use as K source. The processes of physical fractionation and sedimentation in water are inefficient to promote the concentration of K in the different verdete rock fractions. The total K content in some samples are considerable and may enable the use of this rock as raw material for production of more reactive potassium fertilizers.

  19. 21 CFR 520.1696d - Penicillin V potassium tablets.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Penicillin V potassium tablets. 520.1696d Section 520.1696d Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES.... Treatment of respiratory, urogenital, skin and soft tissue infections and septicemia caused by pathogens...

  20. Effect of gibberellic acid and potassium nitrate on seed germination ...

    African Journals Online (AJOL)

    Ramonda serbica and Ramonda nathaliae are rare resurrection plants, endemic and relict species from Balkan Peninsula. The effect of gibberellic acid (GA3) and potassium nitrate (KNO3) were conducted to determine the seed germination response for these two species. An experiment was conducted with four ...

  1. 40 CFR 721.638 - Silyl amine, potassium salt (generic).

    Science.gov (United States)

    2010-07-01

    ...). 721.638 Section 721.638 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... subject to reporting. (1) The chemical substance identified generically as silyl amine, potassium salt... A of this part apply to this section except as modified by this paragraph. (1) Recordkeeping...

  2. Effects of potassium behaviour in soils on crop absorption | Lin ...

    African Journals Online (AJOL)

    Potassium (K) is one of the three major elements that play important roles in plants, such as maintaining turgor of cells, promoting activation of enzymes, and improving efficiency of photosynthesis. The types of K in soil may affect the plant absorption of K. K in soils includes K minerals, K in layered silicates (clay minerals), ...

  3. The mutagenic potentials of potassium bromate and some ...

    African Journals Online (AJOL)

    GREGO

    2007-04-16

    Apr 16, 2007 ... This revealed that potassium bromate is mutagenic in bacteria and could be said to possess carcinogenic potentials. Key words: Food additives, E.coli, Ames spot assay, Mutant strains. INTRODUCTION. Food additives are substances added to preserve flavour or improve the taste and appearance of food.

  4. Characterization of potassium glycinate for carbon dioxide absorption purposes

    NARCIS (Netherlands)

    Portugal, A. F.; Derks, P. W. J.; Versteeg, G. F.; Magalhaes, F. D.; Mendes, A.

    2007-01-01

    Aqueous solutions of potassium glycinate were characterized for carbon dioxide absorption purposes. Density and viscosity of these solutions, with concentrations ranging from 0.1 to 3 M, were determined at temperatures from 293 to 313 K. Diffusivity of CO2 in solution was estimated applying the

  5. the effect of potassium bromate on some haematological parameters ...

    African Journals Online (AJOL)

    Daniel Owu

    wave hair solution (Ueno 2000). Potassium bromate is a substance that has a vapour density of 5.8 (air=1) and density of 3.27. (gcm3) and when in contact with combustible material may cause fire. It is incompatible with organics, reducing agents, aluminum, and finely powdered metals (USEPA 1993). When heated, it.

  6. Yield response of soybeans to levels of nitrogen and potassium ...

    African Journals Online (AJOL)

    A field trail was conducted at the University of Uyo Teaching and Research Farm in a high rainfall area of South eastern Nigeria to assess the yield response soybeans [ Glycine max (L.) Merrill ] to different levels of nitrogen and potassium fertilizers. The results showed that the number of pods/ plant, threshing percentage ...

  7. Syntheses, characterization and crystal structures of potassium and ...

    Indian Academy of Sciences (India)

    Syntheses, characterization and crystal structures of potassium and barium complexes of a Schiff base ligand with different anions. Bhavesh Parmar Kamal Kumar Bisht Pratyush Maiti Parimal Paul Eringathodi Suresh. Special issue on Chemical Crystallography Volume 126 Issue 5 September 2014 pp 1373-1384 ...

  8. Luminescence from potassium feldspars stimulated by infrared and green light

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Bøtter-Jensen, L.

    1993-01-01

    A series of experiments are reported which investigate stimulated luminescence from potassium feldspar. The aim is to provide a basic phenomenological description of the response of the material to stimulation by heat, infrared radiation (875 DELTA 80 nm) and a green light wavelength band from 5 15...

  9. Synthesis and crystal structure of trinuclear potassium(I) complex ...

    African Journals Online (AJOL)

    A furazan-based trinuclear potassium(I) complex derived from the oxy-bridged bis(gem-dinitro)furazan (OBNF) and triaminoguanidinium (TGA) units was synthesized and characterized by elemental analyses, nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The single crystal X-ray structure of the ...

  10. Response of Cassava Variety TMS/98/0505 to Potassium ...

    African Journals Online (AJOL)

    Two field experiments were used to study the response of a low cyanide cassava variety TMS/98/0505 to potassium fertilizer and time of harvest in a tropical ultisol in south eastern Nigeria in 2005/06 and 2006/07. In each year, a split plot design was adopted for the experiment with treatments arranged in a randomized ...

  11. Syntheses, characterization and crystal structures of potassium and ...

    Indian Academy of Sciences (India)

    Syntheses, characterization and crystal structures of potassium and barium complexes of a Schiff base ligand with different anions. BHAVESH PARMARa, KAMAL KUMAR BISHTa,b, PRATYUSH MAITIc, PARIMAL PAULa,b, and ERINGATHODI SURESHa,b,∗. aAnalytical Discipline and Centralized Instrument Facility, ...

  12. ( Leveillula taurica ) on tomato by foliar sprays of liquid potassium ...

    African Journals Online (AJOL)

    A foliar application of soluble silicon (liquid potassium silicate) was tested for the control of powdery mildew of tomato for 2 years in the field conditions on susceptible cultivar Alida F1. Powdery mildew in field-grown staked tomato, caused by Leveillula taurica was significantly controlled by a foliar spray of either K2SiO3 or ...

  13. Acute toxicity of potassium permanganate to fingerlings of the ...

    African Journals Online (AJOL)

    Laboratory static bioassays were conducted to determine the 96-h LC50 and the lethal levels of concentrations of the aquaculture therapeutant, potassium permanganate (KMnO4) on fingerlings (mean weight, 6.24 ± 0.15 g and mean length, 4.25 ± 0.07 cm) of the African catfish, Clarias gariepinus. A total number of one ...

  14. Effect of Metformin on Potassium-adapted and Nonadapted Diabetic ...

    African Journals Online (AJOL)

    Purpose: To assess the effects of potassium adaptation on some biochemical parameters in diabetic rats treated with metformin. Methods: Diabetes was induced via intraperitoneal administration of streptozotocin in potassiumadapted and non-adapted rats and, then metformin (350 mg/kg) was administered orally.

  15. Mechanism of Proarrhythmic Effects of Potassium Channel Blockers

    DEFF Research Database (Denmark)

    Skibsbye, Lasse; Ravens, Ursula

    2016-01-01

    Any disturbance of electrical impulse formation in the heart and of impulse conduction or action potential (AP) repolarization can lead to rhythm disorders. Potassium (K(+)) channels play a prominent role in the AP repolarization process. In this review we describe the causes and mechanisms...

  16. Late termination of pregnancy by intracardiac potassium chloride ...

    African Journals Online (AJOL)

    Objectives. To report our experience with intracardiac potassium chloride (KCl) injection as a method of feticide for severe congenital abnormalities beyond 24 weeksf gestation. Method. A retrospective chart review. Patient demographics and types of fetal anomalies were analysed according to the groups that accepted

  17. ION VATAMANU

    Directory of Open Access Journals (Sweden)

    l. Povar

    2012-12-01

    Full Text Available Ion Vatamanu was a chemist, writer and public figure. He was equally passionate about both his chosen fields of activity: chemistry and poetry. Chemistry, with its perfect equilibrium of logic and precision, provided inspiration for lyrical creativity, whereas poetry writing enlivened his imagination and passion for chemistry. He loved his parents. He adored his wife Elena, whom he often gifted a sea of flowers. He loved his daughters Mihaela, Mariana, and Leontina. He loved life, and he loved people.

  18. Urinary sodium and potassium excretion, mortality, and cardiovascular events.

    Science.gov (United States)

    O'Donnell, Martin; Mente, Andrew; Rangarajan, Sumathy; McQueen, Matthew J; Wang, Xingyu; Liu, Lisheng; Yan, Hou; Lee, Shun Fu; Mony, Prem; Devanath, Anitha; Rosengren, Annika; Lopez-Jaramillo, Patricio; Diaz, Rafael; Avezum, Alvaro; Lanas, Fernando; Yusoff, Khalid; Iqbal, Romaina; Ilow, Rafal; Mohammadifard, Noushin; Gulec, Sadi; Yusufali, Afzal Hussein; Kruger, Lanthe; Yusuf, Rita; Chifamba, Jephat; Kabali, Conrad; Dagenais, Gilles; Lear, Scott A; Teo, Koon; Yusuf, Salim

    2014-08-14

    The optimal range of sodium intake for cardiovascular health is controversial. We obtained morning fasting urine samples from 101,945 persons in 17 countries and estimated 24-hour sodium and potassium excretion (used as a surrogate for intake). We examined the association between estimated urinary sodium and potassium excretion and the composite outcome of death and major cardiovascular events. The mean estimated sodium and potassium excretion was 4.93 g per day and 2.12 g per day, respectively. With a mean follow-up of 3.7 years, the composite outcome occurred in 3317 participants (3.3%). As compared with an estimated sodium excretion of 4.00 to 5.99 g per day (reference range), a higher estimated sodium excretion (≥ 7.00 g per day) was associated with an increased risk of the composite outcome (odds ratio, 1.15; 95% confidence interval [CI], 1.02 to 1.30), as well as increased risks of death and major cardiovascular events considered separately. The association between a high estimated sodium excretion and the composite outcome was strongest among participants with hypertension (P=0.02 for interaction), with an increased risk at an estimated sodium excretion of 6.00 g or more per day. As compared with the reference range, an estimated sodium excretion that was below 3.00 g per day was also associated with an increased risk of the composite outcome (odds ratio, 1.27; 95% CI, 1.12 to 1.44). As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was associated with a reduced risk of the composite outcome. In this study in which sodium intake was estimated on the basis of measured urinary excretion, an estimated sodium intake between 3 g per day and 6 g per day was associated with a lower risk of death and cardiovascular events than was either a higher or lower estimated level of intake. As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was

  19. Potassium fulvate-modified graft copolymer of acrylic acid onto cellulose as efficient chelating polymeric sorbent.

    Science.gov (United States)

    Mohamed, Magdy F; Essawy, Hisham A; Ammar, Nabila S; Ibrahim, Hanan S

    2017-01-01

    Acrylic acid (AA) was graft copolymerized from cellulose (Cell) in presence of potassium fulvate (KF) in order to enhance the chemical activity of the resulting chelating polymer and the handling as well. Fourier transform infrared (FTIR) proved that KF was efficiently inserted and became a permanent part of the network structure of the sorbent in parallel during the grafting copolymerization. Scanning electron microscopy (SEM) revealed intact homogeneous structure with uniform surface. This indicates improvement of the handling, however, it was not the case for the graft copolymer of acrylic acid onto cellulose in absence of KF, which is known to be brittle and lacks mechanical integrity. Effective insertion of this co-interpenetrating agent provided more functional groups, such as OH and COOH, which improved the chelating power of the produced sorbent as found for the removal of Cu(2+) ions from its aqueous solutions (the removal efficiency reached ∼98.9%). Different models were used to express the experimental data. The results corroborated conformity of the pseudo-second order kinetic model and Langmuir isotherm model to the sorption process, which translates into dominance of the chemisorption. Regeneration of the chelating polymers under harsh conditions did not affect the efficiency of copper ions uptake up to three successive cycles. A thermodynamic investigation ensured exothermic nature of the adsorption process that became less favourable at higher temperatures. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Specific effect of zinc ions on DNA polymerase activity of avian myeloblastosis virus.

    Science.gov (United States)

    Palan, P R; Eidinoff, M L

    1978-11-01

    The effect of selected cations on DNA synthesis by DNA-polymerase of avian myeloblastosis virus (AMV) was studied. Zinc ions at low concentration (0.2mM) in the assay system enhanced the activity about 2 x fold and at higher concentration (2.0 mM) inhibited the activity completely. In contrast, addition of lithium and potassium salts produced inhibitory effects in this ionic concentration range. Replacement of K+ ion had an inhibitory effect on the activity.