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https://www.readbyqxmd.com/read/28340472/characterization-of-an-unknown-impurity-in-doxofylline-using-lc-ms-and-nmr
#1
Peixi Zhu, Jingxian Lu, Liya Hong, Weike Su, Ann Van Schepdael, Erwin Adams
During quality control of doxofylline, a novel impurity was detected, which was above the identification threshold defined by ICH. First, a liquid chromatographic method compatible with mass spectrometric (MS) detection was developed. Based on tandem multistage MS and high resolution MS data, the unknown impurity was found to consist of two theophylline groups connected by a methylene group. The structure was further confirmed by 1D and 2D nuclear magnetic resonance (NMR) experiments after semi-preparative isolation...
March 18, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28340407/transmission-of-persistent-ionizing-radiation-induced-foci-through-cell-division-in-human-primary-cells
#2
Aurelie Vaurijoux, Pascale Voisin, Amelie Freneau, Joan Francesc Barquinero, Gaetan Gruel
Unrepaired DNA double-strand breaks (DSBs) induced by ionizing radiation are associated with lethal effects and genomic instability. After the initial breaks and chromatin destabilization, a set of post-translational modifications of histones occurs, including phosphorylation of serine 139 of histone H2AX (γH2AX), which leads to the formation of ionizing radiation-induced foci (IRIF). DSB repair results in the disappearance of most IRIF within hours after exposure, although some remain 24h after irradiation...
March 10, 2017: Mutation Research
https://www.readbyqxmd.com/read/28340349/structure-reveals-mechanisms-of-viral-suppressors-that-intercept-a-crispr-rna-guided-surveillance-complex
#3
Saikat Chowdhury, Joshua Carter, MaryClare F Rollins, Sarah M Golden, Ryan N Jackson, Connor Hoffmann, Lyn'Al Nosaka, Joseph Bondy-Denomy, Karen L Maxwell, Alan R Davidson, Elizabeth R Fischer, Gabriel C Lander, Blake Wiedenheft
Genetic conflict between viruses and their hosts drives evolution and genetic innovation. Prokaryotes evolved CRISPR-mediated adaptive immune systems for protection from viral infection, and viruses have evolved diverse anti-CRISPR (Acr) proteins that subvert these immune systems. The adaptive immune system in Pseudomonas aeruginosa (type I-F) relies on a 350 kDa CRISPR RNA (crRNA)-guided surveillance complex (Csy complex) to bind foreign DNA and recruit a trans-acting nuclease for target degradation. Here, we report the cryo-electron microscopy (cryo-EM) structure of the Csy complex bound to two different Acr proteins, AcrF1 and AcrF2, at an average resolution of 3...
March 23, 2017: Cell
https://www.readbyqxmd.com/read/28340334/advances-in-phase-plate-cryo-em-imaging-of-dna-and-nucleosomes
#4
Eugene Y D Chua, Sara Sandin
Contrast in electron cryo-microscopy (cryo-EM) is limited by the weak phase and radiation sensitive nature of biologic samples embedded in vitrified ice. We have recently shown that a new contrast enhancement technique utilizing the Volta phase plate can be combined with single particle analysis to determine the structure of a small chromatin complex, the nucleosome core particle, at near-atomic resolution. Here, we discuss advantages and limitations of the technique in terms of data collection, particle detection, and visualization of individual DNA molecules and higher-order chromatin structure...
February 7, 2017: Nucleus
https://www.readbyqxmd.com/read/28340294/a-well-defined-osmium-cupin-complex-hyperstable-artificial-osmium-peroxygenase
#5
Nobutaka Fujieda, Takumi Nakano, Yuki Taniguchi, Haruna Ichihashi, Hideki Sugimoto, Yuma Morimoto, Yosuke Nishikawa, Genji Kurisu, Shinobu Itoh
Thermally stable TM1459 cupin superfamily protein from Thermotoga maritima was repurposed as an osmium (Os) peroxygenase by metal-substitution strategy employing the metal-binding promiscuity. This novel artificial metalloenzyme bears a datively bound Os ion supported by the 4-histidine motif. The well-defined Os center is responsible for not only the catalytic activity but also the thermodynamic stability of the protein folding, leading to the robust biocatalyst (Tm ≈ 120 °C). The spectroscopic analysis and atomic resolution X-ray crystal structures of Os-bound TM1459 revealed two types of donor sets to Os center with octahedral coordination geometry...
March 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28339630/mr-tractography-in-short-lasting-unilateral-neuralgiform-headache-attacks-with-conjunctival-injection-and-tearing-sunct-patients-case-reports
#6
Ozlem Coskun, Murat Ucar, Doga Vuralli, Funuzar Yildirim, Rumeysa Cetinkaya, Suna Akin Takmaz, Serap Ucler
Background. : Short-lasting unilateral neuralgiform headache attack with conjunctival injection and tearing (SUNCT) is one of the trigeminal autonomic cephalalgias where neurovascular compression was detected in neuroimaging in recent years. Case. : We report two cases, a 52-year-old adult and a 69-year-old elderly patient with short-lasting and recurrent headache combined with cranial autonomic features. Diffusion tensor imaging (DTI) and magnetic resonance (MR) tractography of both patients outlined structural changes of the trigeminal nerve revealing neurovascular compression...
February 11, 2017: Pain Medicine: the Official Journal of the American Academy of Pain Medicine
https://www.readbyqxmd.com/read/28338100/hyperspectral-imaging-using-the-single-pixel-fourier-transform-technique
#7
Senlin Jin, Wangwei Hui, Yunlong Wang, Kaicheng Huang, Qiushuai Shi, Cuifeng Ying, Dongqi Liu, Qing Ye, Wenyuan Zhou, Jianguo Tian
Hyperspectral imaging technology is playing an increasingly important role in the fields of food analysis, medicine and biotechnology. To improve the speed of operation and increase the light throughput in a compact equipment structure, a Fourier transform hyperspectral imaging system based on a single-pixel technique is proposed in this study. Compared with current imaging spectrometry approaches, the proposed system has a wider spectral range (400-1100 nm), a better spectral resolution (1 nm) and requires fewer measurement data (a sample rate of 6...
March 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28338048/reconfigurable-superconducting-vortex-pinning-potential-for-magnetic-disks-in-hybrid-structures
#8
Estefani Marchiori, Peter J Curran, Jangyong Kim, Nathan Satchell, Gavin Burnell, Simon J Bending
High resolution scanning Hall probe microscopy has been used to directly visualise the superconducting vortex behavior in hybrid structures consisting of a square array of micrometer-sized Py ferromagnetic disks covered by a superconducting Nb thin film. At remanence the disks exist in almost fully flux-closed magnetic vortex states, but the observed cloverleaf-like stray fields indicate the presence of weak in-plane anisotropy. Micromagnetic simulations suggest that the most likely origin is an unintentional shape anisotropy...
March 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28338011/towards-sub-nanometer-real-space-observation-of-spin-and-orbital-magnetism-at-the-fe-mgo-interface
#9
Thomas Thersleff, Shunsuke Muto, Mirosław Werwiński, Jakob Spiegelberg, Yaroslav Kvashnin, Björgvin Hjӧrvarsson, Olle Eriksson, Ján Rusz, Klaus Leifer
While the performance of magnetic tunnel junctions based on metal/oxide interfaces is determined by hybridization, charge transfer, and magnetic properties at the interface, there are currently only limited experimental techniques with sufficient spatial resolution to directly observe these effects simultaneously in real-space. In this letter, we demonstrate an experimental method based on Electron Magnetic Circular Dichroism (EMCD) that will allow researchers to simultaneously map magnetic transitions and valency in real-space over interfacial cross-sections with sub-nanometer spatial resolution...
March 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28337915/nano-raman-scattering-microscopy-resolution-and-enhancement
#10
Satoshi Kawata, Taro Ichimura, Atsushi Taguchi, Yasuaki Kumamoto
Raman scattering microscopy is becoming one of the hot topics in analytical microscopy as a tool for analyzing advanced nanomaterials, such as biomolecules in a live cell for the study of cellular dynamics, semiconductor devices for characterizing strain distribution and contamination, and nanocarbons and nano-2D materials. In this paper, we review the recent progress in the development of Raman scattering microscopy from the viewpoint of spatial resolution and scattering efficiency. To overcome the extremely small cross section of Raman scattering, we discuss three approaches for the enhancement of scattering efficiency and show that the scattering enhancement synergistically increases the spatial resolution...
March 24, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28337516/exploring-the-potential-of-high-resolution-mass-spectrometry-for-the-investigation-of-lignin-derived-phenol-substitutes-in-phenolic-resin-syntheses
#11
Tobias K F Dier, Marco Fleckenstein, Holger Militz, Dietrich A Volmer
Chemical degradation is an efficient method to obtain bio-oils and other compounds from lignin. Lignin bio-oils are potential substitutes for the phenol component of phenol formaldehyde (PF) resins. Here, we developed an analytical method based on high resolution mass spectrometry that provided structural information for the synthesized lignin-derived resins and supported the prediction of their properties. Different model resins based on typical lignin degradation products were analyzed by electrospray ionization in negative ionization mode...
March 23, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28336403/broad-analysis-of-vicinal-disulfides-occurrences-conformations-with-cis-or-with-trans-peptides-and-functional-roles-including-sugar-binding
#12
Jane S Richardson, Lizbeth L Videau, Christopher J Williams, David C Richardson
Vicinal disulfides between sequence-adjacent cysteine residues are very rare and rather startling structural features which play a variety of functional roles. Typically discussed as an isolated curiosity, they have never received a general treatment covering both cis and trans forms. Enabled by the growing database of high-resolution structures, required deposition of diffraction data, and improved methods for discriminating reliable from dubious cases, we here identify and describe distinct protein families with reliably genuine examples of cis or trans vicinal disulfides and discuss their conformations, conservation, and functions...
March 20, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28336292/structural-elucidation-and-physiologic-functions-of-specialized-pro-resolving-mediators-and-their-receptors
#13
REVIEW
Nan Chiang, Charles N Serhan
The acute inflammatory response is host protective to contain foreign invaders. Many of today's pharmacopeia that block pro-inflammatory chemical mediators can cause serious unwanted side effects such as immune suppression. Uncontrolled inflammation is now considered a pathophysiologic basis associated with, many widely occurring diseases such as cardiovascular disease, neurodegenerative diseases, diabetes, obesity and asthma, as well as the classic inflammatory diseases, e.g. arthritis, periodontal diseases...
March 20, 2017: Molecular Aspects of Medicine
https://www.readbyqxmd.com/read/28336213/transient-and-permanent-changes-in-dna-methylation-patterns-in-inorganic-arsenic-mediated-epithelial-to-mesenchymal-transition
#14
Meredith Eckstein, Matthew Rea, Yvonne N Fondufe-Mittendorf
Chronic low dose inorganic arsenic exposure causes cells to take on an epithelial-to-mesenchymal phenotype, which is a crucial process in carcinogenesis. Inorganic arsenic is not a mutagen and thus epigenetic alterations have been implicated in this process. Indeed, during the epithelial-to-mesenchymal transition, morphologic changes to cells correlate with changes in chromatin structure and gene expression, ultimately driving this process. However, studies on the effects of inorganic arsenic exposure/withdrawal on the epithelial-to-mesenchymal transition and the impact of epigenetic alterations in this process are limited...
March 20, 2017: Toxicology and Applied Pharmacology
https://www.readbyqxmd.com/read/28336066/construction-of-protein-based-biosensors-using-ligand-directed-chemistry-for-detecting-analyte-binding
#15
Kei Yamaura, Shigeki Kiyonaka, Itaru Hamachi
Protein-based fluorescent biosensors are powerful tools for quantitative detection of biomolecules or drugs with high sensitivity under physiological conditions. However, conventional methods for construction of biosensors require structural data with high resolution or amino acid sequence information in most cases, which hampers applicability of this method to structurally complicated receptor proteins. To sidestep such limitations, we recently developed a new method that employs ligand-directed chemistry coupled with a bimolecular fluorescence quenching and recovery system, which enabled the conversion of various kinds of membrane-bound receptors to "turn-on" type fluorescent sensors...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28335969/design-synthesis-and-application-of-a-new-class-of-stimuli-responsive-separation-materials
#16
Roshanak Sepehrifar, Reinhard I Boysen, Basil Danylec, Yuanzhong Yang, Kei Saito, Milton T W Hearn
A new class of efficient stationary phase has been investigated for use in the liquid chromatographic separation of low molecular weight analytes and high molecular weight biomolecules, based on the application of immobilised stimuli-responsive polymers (SRPs). To this end, two polymeric units, namely poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(acrylic acid) (PAA) were tethered to a triazine core. The derived poly(2-dimethyl-aminoethyl methacrylate)-block-poly(acrylic acid) (PDMAEMA-b-PAA), as a diblock co-polymer, was then immobilised onto the surface of porous silica particles...
April 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28335724/a-genetic-chronology-for-the-indian-subcontinent-points-to-heavily-sex-biased-dispersals
#17
Marina Silva, Marisa Oliveira, Daniel Vieira, Andreia Brandão, Teresa Rito, Joana B Pereira, Ross M Fraser, Bob Hudson, Francesca Gandini, Ceiridwen Edwards, Maria Pala, John Koch, James F Wilson, Luísa Pereira, Martin B Richards, Pedro Soares
BACKGROUND: India is a patchwork of tribal and non-tribal populations that speak many different languages from various language families. Indo-European, spoken across northern and central India, and also in Pakistan and Bangladesh, has been frequently connected to the so-called "Indo-Aryan invasions" from Central Asia ~3.5 ka and the establishment of the caste system, but the extent of immigration at this time remains extremely controversial. South India, on the other hand, is dominated by Dravidian languages...
March 23, 2017: BMC Evolutionary Biology
https://www.readbyqxmd.com/read/28335513/bioactive-potential-of-marine-macroalgae-from-the-central-red-sea-saudi-arabia-assessed-by-high-throughput-imaging-based-phenotypic-profiling
#18
Stephan Kremb, Constanze Müller, Philippe Schmitt-Kopplin, Christian R Voolstra
Marine algae represent an important source of novel natural products. While their bioactive potential has been studied to some extent, limited information is available on marine algae from the Red Sea. This study aimed at the broad discovery of new bioactivities from a collection of twelve macroalgal species from the Central Red Sea. We used imaging-based High-Content Screening (HCS) with a diverse spectrum of cellular markers for detailed cytological profiling of fractionated algal extracts. The cytological profiles for 3 out of 60 algal fractions clustered closely to reference inhibitors and showed strong inhibitory activities on the HIV-1 reverse transcriptase in a single-enzyme biochemical assay, validating the suggested biological target...
March 20, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28335436/photonic-low-cost-micro-sensor-for-in-line-wear-particle-detection-in-flowing-lube-oils
#19
Jon Mabe, Joseba Zubia, Eneko Gorritxategi
The presence of microscopic particles in suspension in industrial fluids is often an early warning of latent or imminent failures in the equipment or processes where they are being used. This manuscript describes work undertaken to integrate different photonic principles with a micro- mechanical fluidic structure and an embedded processor to develop a fully autonomous wear debris sensor for in-line monitoring of industrial fluids. Lens-less microscopy, stroboscopic illumination, a CMOS imager and embedded machine vision technologies have been merged to develop a sensor solution that is able to detect and quantify the number and size of micrometric particles suspended in a continuous flow of a fluid...
March 14, 2017: Sensors
https://www.readbyqxmd.com/read/28335324/dna-origami-reorganizes-upon-interaction-with-graphite-implications-for-high-resolution-dna-directed-protein-patterning
#20
Masudur Rahman, David Neff, Nathaniel Green, Michael L Norton
Although there is a long history of the study of the interaction of DNA with carbon surfaces, limited information exists regarding the interaction of complex DNA-based nanostructures with the important material graphite, which is closely related to graphene. In view of the capacity of DNA to direct the assembly of proteins and optical and electronic nanoparticles, the potential for combining DNA-based materials with graphite, which is an ultra-flat, conductive carbon substrate, requires evaluation. A series of imaging studies utilizing Atomic Force Microscopy has been applied in order to provide a unified picture of this important interaction of structured DNA and graphite...
October 31, 2016: Nanomaterials
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