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https://www.readbyqxmd.com/read/27914283/binding-pattern-of-intermediate-udp-4-keto-xylose-to-human-udp-xylose-synthase-synthesis-and-std-nmr-of-model-keto-saccharides
#1
Claudia Puchner, Thomas Eixelsberger, Bernd Nidetzky, Lothar Brecker
Human UDP-xylose synthase (hUXS1) exclusively converts UDP-glucuronic acid to UDP-xylose via intermediate UDP-4-keto-xylose (UDP-Xyl-4O). Synthesis of model compounds like methyl-4-keto-xylose (Me-Xyl-4O) is reported to investigate the binding pattern thereof to hUXS1. Hence, selective oxidation of the desired hydroxyl function required employment of protecting group chemistry. Solution behavior of synthesized keto-saccharides was studied without enzyme via (1)H and (13)C NMR spectroscopy with respect to existent forms in deuterated potassium phosphate buffer...
November 5, 2016: Carbohydrate Research
https://www.readbyqxmd.com/read/27913841/membranes-and-the-origin-of-life-a-century-of-conjecture
#2
REVIEW
David Deamer
Cells are the units of all life today, and are defined by their membranous boundaries. The membranes have multiple functions; the most obvious being that, in the absence of a boundary, the systems of functional macromolecular components of the cytosol would spill into the environment and disperse. Membranes also contain the pigments essential for photosynthesis, electron transport enzymes that pump and maintain proton gradients, the ATP synthase that uses proton gradients to produce energy for the cell, and enzymes that use ATP to maintain ion gradients essential for life...
December 2, 2016: Journal of Molecular Evolution
https://www.readbyqxmd.com/read/27912180/radicals-formed-from-proton-loss-of-carotenoid-radical-cations-a-special-form-of-carotenoid-neutral-radical-occurring-in-photoprotection
#3
A Ligia Focsan, Lowell D Kispert
In an organized assembly in Arabidopsis thaliana plant, proton loss from the radical cation of zeaxanthin (Zea(+)) was found to occur under intense illumination, a possible component in photoprotection. A stable neutral radical is formed because of the favorable proton loss at C4(4') position(s) of the terminal ends of Zea(+) that extends the unpaired spin density distribution (notation Zea(4) or Zea(4') by symmetry). Proton loss from the radical cation of β-carotene (β-car(+)) to available proton acceptors was also detected in a PSII sample upon irradiation...
November 19, 2016: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/27912143/coupling-of-helix-e-f-motion-with-the-o-nitrito-and-2-nitrovinyl-coordination-in-myoglobin
#4
Androulla Ioannou, Alexandra Lambrou, Vangelis Daskalakis, Eftychia Pinakoulaki
Myoglobin (Mb) is known to react slowly with nitirite to form the green pigment by NO2(-) cordination to the heme Fe in the O-binding nitrito (O1NO2) mode and to the heme 2-vinyl position. Nitrite is a powerful oxidizing agent and a biological reservoir for NO that has been implicated in a variety of aerobic biological systems. Accordingly, it is important to elucidate the nature and variety of NO2(-) reaction mechanisms with Mb. We have performed principal component analysis (PCA, or essential dynamics) on Molecular Dynamics trajectories of all MbNO2 coordination states to resolve the most important motions in the protein at 298K...
November 25, 2016: Biophysical Chemistry
https://www.readbyqxmd.com/read/27912063/structure-of-mammalian-respiratory-supercomplex-i1iii2iv1
#5
Meng Wu, Jinke Gu, Runyu Guo, Yushen Huang, Maojun Yang
The mammalian respiratory chain complexes assemble into supercomplexes (SCs) and reside in the inner mitochondrial membrane to transfer electrons and establish the proton gradient for complex V to synthesize ATP. The precise arrangement of SCs is largely unknown. Here, we report a 4.0-Å cryo-electron microscopy (cryo-EM) structure of the major SC in porcine heart, the 1.7-MDa SCI1III2IV1. The complex III (CIII) dimer and complex IV (CIV) bind at the same side of the L-shaped complex I (CI). Several accessory or supernumerary subunits of CI, such as NDUFA11, NDUFB4, NDUFB8, and NDUFB9, directly contribute to the oligomerization of CI, CIII, and CIV...
December 1, 2016: Cell
https://www.readbyqxmd.com/read/27911973/prevalence-of-osteopenia-and-osteoporosis-in-patients-with-noncystic-fibrosis-bronchiectasis
#6
Nathan Diehl, Margaret M Johnson
OBJECTIVE: The objective of our study was to define the prevalence of osteoporosis and osteopenia in patients with noncystic fibrosis bronchiectasis (NCFB). METHODS: We conducted a retrospective chart review of all patients with physician-diagnosed NCFB evaluated at Mayo Clinic Florida between January 1, 2011 and June 3, 2013. RESULTS: A total of 113 patients with physician-diagnosed NCFB and confirmatory findings on computed tomography scan were identified...
December 2016: Southern Medical Journal
https://www.readbyqxmd.com/read/27911811/the-structure-of-the-catechin-binding-site-of-human-sulfotransferase-1a1
#7
Ian Cook, Ting Wang, Mark Girvin, Thomas S Leyh
We are just beginning to understand the allosteric regulation of the human cytosolic sulfotransferase (SULTs) family-13 disease-relevant enzymes that regulate the activities of hundreds, if not thousands, of signaling small molecules. SULT1A1, the predominant isoform in adult liver, harbors two noninteracting allosteric sites, each of which binds a different molecular family: the catechins (naturally occurring flavonols) and nonsteroidal antiinflammatory drugs (NSAIDs). Here, we present the structure of an SULT allosteric binding site-the catechin-binding site of SULT1A1 bound to epigallocatechin gallate (EGCG)...
November 23, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27911737/the-conservation-of-phosphate-binding-residues-among-pht1-transporters-suggests-that-distinct-transport-affinities-are-unlikely-to-result-from-differences-in-the-phosphate-binding-site
#8
REVIEW
S Antony Ceasar, Alison Baker, Stephen P Muench, S Ignacimuthu, Stephen A Baldwin
The plant PHosphate Transporter 1 (PHT1) family of membrane proteins belongs to the major facilitator super family and plays a major role in the acquisition of inorganic phosphate (Pi) from the soil and its transport within the plant. These transporters have been well characterized for expression patterns, localization, and in some cases affinity. Furthermore, the crystal structure of a high-affinity eukaryotic phosphate transporter from the fungus Piriformospora indica (PiPT) has revealed important information on the residues involved in Pi transport...
October 15, 2016: Biochemical Society Transactions
https://www.readbyqxmd.com/read/27911450/uveal-melanoma-relatively-rare-but-deadly-cancer
#9
REVIEW
S Kaliki, C L Shields
Although it is a relatively rare disease, primarily found in the Caucasian population, uveal melanoma is the most common primary intraocular tumor in adults with a mean age-adjusted incidence of 5.1 cases per million per year. Tumors are located either in iris (4%), ciliary body (6%), or choroid (90%). The host susceptibility factors for uveal melanoma include fair skin, light eye color, inability to tan, ocular or oculodermal melanocytosis, cutaneous or iris or choroidal nevus, and BRCA1-associated protein 1 mutation...
December 2, 2016: Eye
https://www.readbyqxmd.com/read/27911262/magnetic-resonance-elastography-vs-transient-elastography-in-detection-of-fibrosis-and-noninvasive-measurement-of-steatosis-in-patients-with-biopsy-proven-nonalcoholic-fatty-liver-disease
#10
Charlie C Park, Phirum Nguyen, Carolyn Hernandez, Ricki Bettencourt, Kimberly Ramirez, Lynda Fortney, Jonathan Hooker, Ethan Sy, Mosab H Alquiraish, Mark A Valasek, Emily Rizo, Lisa Richards, David Brenner, Claude B Sirlin, Rohit Loomba
BACKGROUND & AIMS: Magnetic-resonance-imaging (MRI) techniques and ultrasound-based transient elastography (TE) can be used in noninvasive diagnosis of fibrosis and steatosis in patients with nonalcoholic fatty liver disease (NAFLD). We performed a prospective study to compare the performance of magnetic resonance elastography (MRE) vs TE for in diagnosis of fibrosis, and MRI-based proton density fat fraction (MRI-PDFF) analysis vs TE-based controlled attenuation parameter (CAP) for diagnosis of steatosis in patients undergoing biopsy to assess NAFLD...
October 27, 2016: Gastroenterology
https://www.readbyqxmd.com/read/27911139/volumetric-response-of-intracranial-meningioma-after-photon-or-particle-irradiation
#11
Petra Mozes, Jan Oliver Dittmar, Daniel Habermehl, Eric Tonndorf-Martini, Katalin Hideghety, Anne Dittmar, Jürgen Debus, Stephanie E Combs
BACKGROUND: Meningiomas are usually slow growing, well circumscribed intracranial tumors. In symptom-free cases observation with close follow-up imaging could be performed. Symptomatic meningiomas could be surgically removed and/or treated with radiotherapy. The study aimed to evaluate the volumetric response of intracranial meningiomas at different time points after photon, proton, and a mixed photon and carbon ion boost irradiation. PATIENTS AND METHODS: In Group A 38 patients received proton therapy (median dose: 56 GyE in 1...
December 2, 2016: Acta Oncologica
https://www.readbyqxmd.com/read/27911033/regioselective-synthesis-of-%C3%AE-fluorinated-cyclopentenones-via-organocatalytic-difluorocyclopropanation-and-fluorine-directed-and-activated-nazarov-cyclization
#12
Kohei Fuchibe, Ryo Takayama, Takaharu Yokoyama, Junji Ichikawa
Silyl dienol ethers, prepared from α,β-unsaturated ketones, underwent proton sponge-catalyzed difluorocyclopropanation with trimethylsilyl 2,2-difluoro-2-fluorosulfonylacetate (TFDA) in a regioselective manner, leading to 1,1-difluoro-2-siloxy-2-vinylcyclopropanes in good yields. The cyclopropanes thus obtained were in turn subjected to fluoride ion-catalyzed ring opening to afford 1-fluorovinyl vinyl ketones (i.e., Nazarov precursors). Treatment of the precursors with Me3Si+ B(OTf)4- regioselectively promoted the Nazarov cyclization, whose rate and regioselectivity were drastically enhanced by the fluorine substituent, thereby facilitating efficient synthesis of biologically promising α-fluorocyclopentenone derivatives...
December 2, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27910848/a-grand-unified-model-for-liganded-gold-clusters
#13
Wen Wu Xu, Beien Zhu, Xiao Cheng Zeng, Yi Gao
A grand unified model (GUM) is developed to achieve fundamental understanding of rich structures of all 71 liganded gold clusters reported to date. Inspired by the quark model by which composite particles (for example, protons and neutrons) are formed by combining three quarks (or flavours), here gold atoms are assigned three 'flavours' (namely, bottom, middle and top) to represent three possible valence states. The 'composite particles' in GUM are categorized into two groups: variants of triangular elementary block Au3(2e) and tetrahedral elementary block Au4(2e), all satisfying the duet rule (2e) of the valence shell, akin to the octet rule in general chemistry...
December 2, 2016: Nature Communications
https://www.readbyqxmd.com/read/27910821/reply-to-comment-on-imaging-of-prompt-gamma-rays-emitted-during-delivery-of-clinical-proton-beams-with-a-compton-camera-feasibility-studies-for-range-verification
#14
Jerimy C Polf, Stephen Avery, Dennis S Mackin, Sam Beddar
A reply is provided to the points raised in the comment by Dr Sitek (2016 Phys. Med. Biol. 61 8941) on Polf et al (2015 Phys. Med. Biol. 60 7085).
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910819/comment-on-imaging-of-prompt-gamma-rays-emitted-during-delivery-of-clinical-proton-beams-with-a-compton-camera-feasibility-studies-for-range-verification
#15
Arkadiusz Sitek
The origin ensemble (OE) algorithm is a new method used for image reconstruction from nuclear tomographic data. The main advantage of this algorithm is the ease of implementation for complex tomographic models and the sound statistical theory. In this comment, the author provides the basics of the statistical interpretation of OE and gives suggestions for the improvement of the algorithm in the application to prompt gamma imaging as described in Polf et al (2015 Phys. Med. Biol. 60 7085).
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910684/a-stretch-compress-scheme-for-a-high-temporal-resolution-detector-for-the-magnetic-recoil-spectrometer-time-mrst
#16
T J Hilsabeck, J A Frenje, J D Hares, C W Wink
A time-resolved detector concept for the magnetic recoil spectrometer for time-resolved measurements of the NIF neutron spectrum is presented. The measurement is challenging due to the time spreading of the recoil protons (or deuterons) as they transit an energy dispersing magnet system. Ions arrive at the focal plane of the magnetic spectrometer over an interval of tens of nanoseconds. We seek to measure the time-resolved neutron spectrum with 20 ps precision by manipulating an electron signal derived from the ions...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910618/faraday-cup-type-lost-fast-ion-detector-on-heliotron-j
#17
S Yamamoto, K Ogawa, M Isobe, D S Darrow, S Kobayashi, K Nagasaki, H Okada, T Minami, S Kado, S Ohshima, G M Weir, Y Nakamura, S Konoshima, N Kemmochi, Y Ohtani, T Mizuuchi
A Faraday-cup type lost-fast ion probe (FLIP) has been designed and installed in Heliotron J for the purpose of the studies of interaction between fast ions and MHD instabilities. The FLIP can measure the co-going fast ions whose energy is in the range of 1.7-42.5 keV (proton) and pitch angle of 90(∘)-140(∘), especially for fast ions having the injection energy of neutral beam injection (NBI). The FLIP successfully measured the re-entering passing ions and trapped lost-fast ions caused by fast-ion-driven energetic particle modes in NBI heated plasmas...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910586/a-novel-method-to-recover-dd-fusion-proton-cr-39-data-corrupted-by-fast-ablator-ions-at-omega-and-the-national-ignition-facility
#18
G D Sutcliffe, L M Milanese, D Orozco, B Lahmann, M Gatu Johnson, F H Séguin, H Sio, J A Frenje, C K Li, R D Petrasso, H-S Park, J R Rygg, D T Casey, R Bionta, D P Turnbull, C M Huntington, J S Ross, A B Zylstra, M J Rosenberg, V Yu Glebov
CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910571/a-collimated-neutron-detector-for-rfp-plasmas-in-mst
#19
W J Capecchi, J K Anderson, P J Bonofiglo, J Kim, S Sears
The neutron emissivity profile in the Madison Symmetric Torus is being reconstructed through the use of a collimated neutron detector. A scintillator-photomultiplier tube (PMT) system is employed to detect the fusion neutrons with the plasma viewing volume defined by a 55 cm deep, 5 cm diameter aperture. Effective detection of neutrons from the viewing volume is achieved through neutron moderation using 1300 lbs of high density polyethylene shielding, which modeling predicts attenuates the penetrating flux by a factor of 10(4) or more...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910557/a-storage-ring-experiment-to-detect-a-proton-electric-dipole-moment
#20
V Anastassopoulos, S Andrianov, R Baartman, S Baessler, M Bai, J Benante, M Berz, M Blaskiewicz, T Bowcock, K Brown, B Casey, M Conte, J D Crnkovic, N D'Imperio, G Fanourakis, A Fedotov, P Fierlinger, W Fischer, M O Gaisser, Y Giomataris, M Grosse-Perdekamp, G Guidoboni, S Hacıömeroğlu, G Hoffstaetter, H Huang, M Incagli, A Ivanov, D Kawall, Y I Kim, B King, I A Koop, D M Lazarus, V Lebedev, M J Lee, S Lee, Y H Lee, A Lehrach, P Lenisa, P Levi Sandri, A U Luccio, A Lyapin, W MacKay, R Maier, K Makino, N Malitsky, W J Marciano, W Meng, F Meot, E M Metodiev, L Miceli, D Moricciani, W M Morse, S Nagaitsev, S K Nayak, Y F Orlov, C S Ozben, S T Park, A Pesce, E Petrakou, P Pile, B Podobedov, V Polychronakos, J Pretz, V Ptitsyn, E Ramberg, D Raparia, F Rathmann, S Rescia, T Roser, H Kamal Sayed, Y K Semertzidis, Y Senichev, A Sidorin, A Silenko, N Simos, A Stahl, E J Stephenson, H Ströher, M J Syphers, J Talman, R M Talman, V Tishchenko, C Touramanis, N Tsoupas, G Venanzoni, K Vetter, S Vlassis, E Won, G Zavattini, A Zelenski, K Zioutas
A new experiment is described to detect a permanent electric dipole moment of the proton with a sensitivity of 10(-29) e ⋅ cm by using polarized "magic" momentum 0.7 GeV/c protons in an all-electric storage ring. Systematic errors relevant to the experiment are discussed and techniques to address them are presented. The measurement is sensitive to new physics beyond the standard model at the scale of 3000 TeV.
November 2016: Review of Scientific Instruments
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