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Dynamic nuclear polarization

Ying Zhang, Xiaoyu Guo, Juan Dong
Cell polarization is commonly used for the regulation of stem cell asymmetric division in both animals and plants. Stomatal development in Arabidopsis, a process that produces breathing pores in the epidermis, requires asymmetric cell division to differentiate highly specialized guard cells while maintaining a stem cell population [1, 2]. The BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE (BASL) protein exhibits a polarized localization pattern in the cell and is required for differential cell fates resulting from asymmetric cell division [3]...
October 5, 2016: Current Biology: CB
Björn Corzilius
Correction for 'Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids' by Björn Corzilius et al., Phys. Chem. Chem. Phys., 2016, DOI: .
October 13, 2016: Physical Chemistry Chemical Physics: PCCP
Tanya K Todorova, Xavier Rozanska, Christel Gervais, Alexandre Legrand, Linh N Ho, Pierrick Berruyer, Anne Lesage, Lyndon Emsley, David Farrusseng, Jérôme Canivet, Caroline Mellot-Draznieks
We use density functional theory, newly parameterized molecular dynamics simulations, and last generation (15) N dynamic nuclear polarization surface enhanced solid-state NMR spectroscopy (DNP SENS) to understand graft-host interactions and effects imposed by the metal-organic framework (MOF) host on peptide conformations in a peptide-functionalized MOF. Focusing on two grafts typified by MIL-68-proline (-Pro) and MIL-68-glycine-proline (-Gly-Pro), we identified the most likely peptide conformations adopted in the functionalized hybrid frameworks...
October 11, 2016: Chemistry: a European Journal
Yaewon Kim, Mengxiao Liu, Christian Hilty
Protein-ligand interactions are frequently screened using nuclear magnetic resonance (NMR) spectroscopy. The dissociation constant (KD) of a ligand of interest can be determined via a spin-spin relaxation measurement of a reporter ligand, in a single scan when using hyperpolarization by means of dissolution dynamic nuclear polarization (D-DNP). Despite nearly instantaneous signal acquisition, a limitation of D-DNP for the screening of protein-ligand interactions is the required polarization time on the order of tens of minutes...
October 10, 2016: Analytical Chemistry
Yixun Xing, Ashish K Jindal, Martín Regueiro-Figueroa, Mariane Le Fur, Nelly Kervarec, Piyu Zhao, Zoltan Kovacs, Laura Valencia, Paulo Pérez-Lourido, Raphaël Tripier, David Esteban-Gómez, Carlos Platas-Iglesias, A Dean Sherry
Recently developed dynamic nuclear polarization (DNP) technology offers the potential of increasing the NMR sensitivity of even rare nuclei for biological imaging applications. Hyperpolarized (89) Y is an ideal candidate because of its narrow NMR linewidth, favorable spin quantum number (I=1/2 ), and long longitudinal relaxation times (T1 ). Strong NMR signals were detected in hyperpolarized (89) Y samples of a variety of yttrium complexes. A dataset of (89) Y NMR data composed of 23 complexes with polyaminocarboxylate ligands was obtained using hyperpolarized (89) Y measurements or (1) H,(89) Y-HMQC spectroscopy...
October 10, 2016: Chemistry: a European Journal
P Goossens, C Martineau-Corcos, F Saïdi, J A Martens, F Taulelle
Nafion proton exchange membranes (PEMs) for fuel cell applications are extensively studied and commercially applied, but their unique proton conduction capabilities are still somewhat unexplained. For studying proton dynamics in situ, molecular level spectroscopic techniques have been of limited utility so far. By solid-state (1)H and (19)F double resonance nuclear magnetic resonance (NMR) spectroscopy using the recently revived multiple contact cross-polarization (MC-CP) pulse sequence along with double-quantum (1)H-(1)H filtering, high resolution proton populations distinct from the dominant water resonance were observed in Nafion for the first time...
October 7, 2016: Physical Chemistry Chemical Physics: PCCP
Nathalie Nielsen, Christoffer Laustsen, Lotte Bonde Bertelsen
Endothelial progenitor cells (EPCs) represent a heterogeneous cell population that is believed to be involved in vasculogenesis. With the purpose of enhancing endothelial repair, EPCs could have a potential for future cell therapies. Due to the low amount of EPCs in the peripheral circulating blood, in vitro expansion is needed before administration to recipients and the effects of in vitro culturing is still an under-evaluated field with little knowledge of how the cells change over time in culture. The aim of this study was to use hyperpolarised carbon-13 magnetic resonance spectroscopy to profile important metabolic pathways in a population of progenitor cells and to show that cell culturing in 3D scaffolds seem to block the metabolic processes that leads to cell senescence...
October 5, 2016: Experimental Cell Research
Vladimir V Zhivonitko, Kristina Sorochkina, Konstantin Chernichenko, Bianka Kótai, Tamás Földes, Imre Pápai, Ville-Veikko Telkki, Timo Repo, Igor Koptyug
The parahydrogen-induced polarization (PHIP) phenomenon, observed when parahydrogen is used in H2 addition processes, provides a means for substantial NMR signal enhancements and mechanistic studies of chemical reactions. Commonly, noble metal complexes are used for parahydrogen activation, whereas metal-free activation is rare. Herein, we report a series of unimolecular metal-free frustrated Lewis pairs based on an ansa-aminoborane (AAB) moiety in the context of PHIP. These molecules, which have a "molecular tweezers" structure, differ in their substituents at the boryl site (-H, -Ph, -o-iPr-Ph, and -Mes)...
October 12, 2016: Physical Chemistry Chemical Physics: PCCP
Johannes Niskanen, Kuno Kooser, Jaakko Koskelo, Tanel Käämbre, Kristjan Kunnus, Annette Pietzsch, Wilson Quevedo, Mikko Hakala, Alexander Föhlisch, Simo Huotari, Edwin Kukk
In this paper we report an experimental and computational study of liquid acetonitrile (H3C-C[triple bond, length as m-dash]N) by resonant inelastic X-ray scattering (RIXS) at the N K-edge. The experimental spectra exhibit clear signatures of the electronic structure of the valence states at the N site and incident-beam-polarization dependence is observed as well. Moreover, we find fine structure in the quasielastic line that is assigned to finite scattering duration and nuclear relaxation. We present a simple and light-to-evaluate model for the RIXS maps and analyze the experimental data using this model combined with ab initio molecular dynamics simulations...
September 21, 2016: Physical Chemistry Chemical Physics: PCCP
Filippo Caracciolo, Marta Filibian, Pietro Carretta, Alberto Rosso, Andrea De Luca
In dynamic nuclear polarization (DNP) experiments, the compound is driven out-of-equilibrium by the microwave (MW) irradiation of the radical electron spins. Their stationary state has been recently probed via electron double resonance (ELDOR) techniques showing, at low temperature, a broad depolarization of the electron paramagnetic resonance (EPR) spectrum under microwave irradiation. In this theoretical manuscript, we develop a numerical method to compute exactly the EPR spectrum in the presence of dipolar interactions...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
David A Hirsh, Aaron J Rossini, Lyndon Emsley, Robert W Schurko
In this work, we show how to obtain efficient dynamic nuclear polarization (DNP) enhanced (35)Cl solid-state NMR (SSNMR) spectra at 9.4 T and demonstrate how they can be used to characterize the molecular-level structure of hydrochloride salts of active pharmaceutical ingredients (APIs) in both bulk and low wt% API dosage forms. (35)Cl SSNMR central-transition powder patterns of chloride ions are typically tens to hundreds of kHz in breadth, and most cannot be excited uniformly with high-power rectangular pulses or acquired under conditions of magic-angle spinning (MAS)...
September 21, 2016: Physical Chemistry Chemical Physics: PCCP
Ronja M Malinowski, Kasper W Lipsø, Mathilde H Lerche, Jan H Ardenkjær-Larsen
Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden of the hyperpolarized product is by use of a closed fluid path that constitutes a barrier to contamination. The fluid path can be filled with the pharmaceuticals, i.e. imaging agent and solvents, in a clean room, and then stored or immediately used at the polarizer...
September 22, 2016: Journal of Magnetic Resonance
Diptesh Dey, Ashwani Kumar Tiwari
Quantum dynamical behaviour of H2(+) in the presence of linearly polarized, ultrashort, intense, infrared laser pulse has been studied by numerically solving the time-dependent Schrödinger equation with nuclear motion restricted in one-dimension along the direction of laser polarization and electronic motion in three-dimensions. Based on time-dependent Born-Oppenheimer approximation, we have constructed time-dependent potentials for the ground electronic state 1sσg of H2(+). Subsequent nuclear dynamics is then carried out on these field-dressed potential energy surfaces and the dissociation dynamics is investigated...
October 3, 2016: Journal of Physical Chemistry. A
Kasper Wigh Lipsø, Esben Søvsø Szocska Hansen, Rasmus Stilling Tougaard, Christoffer Laustsen, Jan Henrik Ardenkjaer-Larsen
PURPOSE: To study hyperpolarized water as an angiography and perfusion tracer in a large animal model. METHODS: Protons dissolved in deuterium oxide (D2 O) were hyperpolarized in a SPINlab dissolution dynamic nuclear polarization (dDNP) polarizer and subsequently investigated in vivo in a pig model at 3 Tesla (T). Approximately 15 mL of hyperpolarized water was injected in the renal artery by hand over 4-5 s. RESULTS: A liquid state polarization of 5...
September 30, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Guannan Zhang, Franz Schilling, Steffen J Glaser, Christian Hilty
Off-resonance decoupling using the method of Scaling of Heteronuclear Couplings by Optimal Tracking (SHOT) enables determination of heteronuclear correlations of chemical shifts in single scan NMR spectra. Through modulation of J-coupling evolution by shaped radio frequency pulses, off resonance decoupling using SHOT pulses causes a user-defined dependence of the observed J-splitting, such as the splitting of (13)C peaks, on the chemical shift offset of coupled nuclei, such as (1)H. Because a decoupling experiment requires only a single scan, this method is suitable for characterizing on-going chemical reactions using hyperpolarization by dissolution dynamic nuclear polarization (D-DNP)...
September 14, 2016: Journal of Magnetic Resonance
C Gainaru, E W Stacy, V Bocharova, M Gobet, A P Holt, T Saito, S Greenbaum, A P Sokolov
Combining broadband impedance spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance we analyzed charge and mass transport in two polymerized ionic liquids and one of their monomeric precursors. In order to establish a general procedure for extracting single-particle diffusivity from their conductivity spectra, we critically assessed several approaches previously employed to describe the onset of diffusive charge dynamics and of the electrode polarization in ion conducting materials...
October 14, 2016: Journal of Physical Chemistry. B
Mor Mishkovsky, Arnaud Comment
The advent of dissolution dynamic nuclear polarization (DNP) led to the emergence of a new kind of magnetic resonance (MR) measurements providing the opportunity to probe metabolism in vivo in real time. It has been shown that, following the injection of hyperpolarized substrates prepared using dissolution DNP, specific metabolic bioprobes that can be used to differentiate between healthy and pathological tissue in preclinical and clinical studies can be readily detected by MR thanks to the tremendous signal enhancement...
September 22, 2016: Analytical Biochemistry
Elisa Lehnert, Jiafei Mao, Ahmad Reza Mehdipour, Gerhard Hummer, Rupert Abele, Clemens Glaubitz, Robert Tampé
The human transporter associated with antigen processing (TAP) is a 150 kDa heterodimeric ABC transport complex that selects peptides for export into the endoplasmic reticulum and subsequent loading onto major histocompatibility complex class I molecules to trigger adaptive immune responses against virally or malignantly transformed cells. To date, no atomic-resolution information on peptide-TAP interactions has been obtained, hampering a mechanistic understanding of the early steps of substrate translocation catalyzed by TAP...
October 17, 2016: Journal of the American Chemical Society
Cristal Cerqueira-Coutinho, Elisabete P Dos Santos, Claudia Regina E Mansur
Nanosystems used in the pharmaceutical field aim to guarantee a controlled release and efficacy boost with dose reduction of the drug. The same active ingredient could be vehiculated in different concentrations in distinct nanosystems. Among these nanostructures, the vesicular ones present a versatile delivery system that could be applied to encapsulate lipophilic, amphiphilic, and hydrophilic compounds. Liposomes are the most well-known vesicular nanosystems; however, there are others, such as niosomes, that are composed of nonionic surfactants that are polymeric or conventional...
2016: Critical Reviews in Therapeutic Drug Carrier Systems
Adel Sepsi, James D Higgins, J S Pat Heslop-Harrison, Trude Schwarzacher
During meiosis, centromeres in some species undergo a series of associations, but the processes and progression to homologous pairing is still a matter of debate. Here, we aimed to correlate meiotic centromere dynamics and early telomere behaviour to the progression of synapotonemal complex (SC) construction in hexaploid wheat (2n=42) by triple immunolabelling of CENH3 protein marking functional centromeres, and SC proteins ASY1 (unpaired lateral elements) and ZYP1 (central elements in synapsed chromosomes)...
September 14, 2016: Plant Journal: for Cell and Molecular Biology
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