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https://www.readbyqxmd.com/read/28645021/development-a-validated-highly-sensitive-lc-ms-ms-method-for-simultaneous-quantification-of-ledipasvir-sofosbuvir-and-its-major-metabolite-gs-331007-in-human-plasma-application-to-a-human-pharmacokinetic-study
#1
Ola M Abdallah, Ahmed M Abdel-Megied, Amira S Gouda
A highly sensitive and rapid LC-MS/MS method was developed, fully optimized and validated for the simultaneous determination of Ledipasvir (LED) and Sofosbuvir (SOF) in the presence of its major metabolite GS-331007 in human plasma using Daclatasvir as internal standard (IS). The extraction of analytes and IS from plasma was performed using liquid-liquid extraction with ethyl acetate. The chromatographic separation of these prepared samples was achieved on Xterra MS C8 column (4.6×50mm,5μm) using gradient elution with a mobile phase of ammonium formate buffer (pH 3...
June 20, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28644617/dynamic-covalent-chemistry-of-carbon-dioxide-opportunities-to-address-environmental-issues
#2
Jean Septavaux, Geoffroy Germain, Julien Leclaire
Extraction and purification of basic chemicals from complex mixtures has been a persistent issue throughout the development of the chemical sciences. The chemical industry and academic research have grown over the centuries by following a deconstruction-reconstruction approach, reminiscent of the metabolism process. Chemists have designed and optimized extraction, purification, and transformation processes of molecules from natural deposits (fossil fuels, biomass, ores), in order to reassemble them into complex adducts...
June 23, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28644616/importance-of-a-fully-anharmonic-treatment-of-equilibrium-isotope-fractionation-properties-of-dissolved-ionic-species-as-evidenced-by-li-aq
#3
Romain Dupuis, Magali Benoit, Mark E Tuckerman, Merlin Méheut
Equilibrium fractionation of stable isotopes is critically important in fields ranging from chemistry, including medicinal chemistry, electrochemistry, geochemistry, and nuclear chemistry, to environmental science. The dearth of reliable estimates of equilibrium fractionation factors, from experiment or from natural observations, has created a need for accurate computational approaches. Because isotope fractionation is a purely quantum mechanical phenomenon, exact calculation of fractionation factors is nontrivial...
June 23, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28644382/metal-ion-loaded-nanofibre-matrices-for-calcification-inhibition-in-polyurethane-implants
#4
Charanpreet Singh, Xungai Wang
Pathologic calcification leads to structural deterioration of implant materials via stiffening, stress cracking, and other structural disintegration mechanisms, and the effect can be critical for implants intended for long-term or permanent implantation. This study demonstrates the potential of using specific metal ions (MI)s for inhibiting pathological calcification in polyurethane (PU) implants. The hypothesis of using MIs as anti-calcification agents was based on the natural calcium-antagonist role of Mg(2+) ions in human body, and the anti-calcification effect of Fe(3+) ions in bio-prosthetic heart valves has previously been confirmed...
June 23, 2017: Journal of Functional Biomaterials
https://www.readbyqxmd.com/read/28643951/magnetic-graphene-oxide-modified-by-imidazole-based-ionic-liquids-for-the-magnetic-based-solid-phase-extraction-of-polysaccharides-from-brown-alga
#5
Xiaoqin Wang, Guizhen Li, Kyung Ho Row
Magnetic graphene oxide was modified by four imidazole-based ionic liquids to synthesize materials for the extraction of polysaccharides by magnetic solid-phase extraction. Fucoidan and laminarin were chosen as the representative polysaccharides owing to their excellent pharmaceutical value and availability. FTIR spectroscopy, field-emission scanning electron microscopy and thermogravimetric analysis were applied to characterize the synthesized materials. Single-factor experiments showed that the extraction efficiency of polysaccharides was affected by the amount of ionic liquids for modification, solid-liquid ratio of brown alga and ethanol, the stirring time of brown alga and ionic liquid modified magnetic graphene oxide materials, and amount of 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide materials added to the brown alga sample solution...
June 23, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28643517/a-novel-strategy-for-comprehensive-profiling-and-identification-of-acidic-glycosphingolipids-using-ultra-high-performance-liquid-chromatography-coupled-with-quadrupole-time-of-flight-mass-spectrometry
#6
Ting Hu, Zhixin Jia, Jinlan Zhang
Acidic glycosphingolipids (AGSLs), which mainly consist of ganglioside and sulfatide moieties, are highly concentrated in the central nervous system. Comprehensive profiling of AGSLs has historically been challenging because of their high complexity and the lack of standards. In this paper, a novel strategy was developed to comprehensively profile AGSLs using ultra-high-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS). Ganglioside isomers with different glycan chains such as GD1a/ GD1b were completely separated on a C18 column for the first time to our knowledge, facilitated by the addition of formic acid in the mobile phase...
June 23, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28643233/assessing-environmental-exposure-to-%C3%AE-n-methylamino-l-alanine-bmaa-in-complex-sample-matrices-a-comparison-of-the-three-most-popular-lc-ms-ms-methods
#7
Teesha C Baker, Fiona J M Tymm, Susan J Murch
β-N-Methylamino-L-alanine (BMAA) is a naturally occurring non-protein amino acid produced by cyanobacteria, accumulated through natural food webs, found in mammalian brain tissues. Recent evidence indicates an association between BMAA and neurological disease. The accurate detection and quantification of BMAA in food and environmental samples are critical to understanding BMAA metabolism and limiting human exposure. To date, there have been more than 78 reports on BMAA in cyanobacteria and human samples, but different methods give conflicting data and divergent interpretations in the literature...
June 22, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28642482/moving-bragg-grating-solitons-in-a-semilinear-dual-core-system-with-dispersive-reflectivity
#8
S A M Saddam Chowdhury, Javid Atai
The existence, stability and collision dynamics of moving Bragg grating solitons in a semilinear dual-core system where one core has the Kerr nonlinearity and is equipped with a Bragg grating with dispersive reflectivity, and the other core is linear are investigated. It is found that moving soliton solutions exist as a continuous family of solutions in the upper and lower gaps of the system's linear spectrum. The stability of the moving solitons are investigated by means of systematic numerical stability analysis, and the effect and interplay of various parameters on soliton stability are analyzed...
June 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28641835/rapid-purification-of-diastereoisomers-from-piper-kadsura-using-supercritical-fluid-chromatography-with-chiral-stationary-phases
#9
Huaxia Xin, Zhuoshun Dai, Jianfeng Cai, Yanxiong Ke, Hui Shi, Qing Fu, Yu Jin, Xinmiao Liang
Supercritical fluid chromatography (SFC) with chiral stationary phases (CSPs) is an advanced solution for the separation of achiral compounds in Piper kadsura. Analogues and stereoisomers are abundant in natural products, but there are obstacles in separation using conventional method. In this paper, four lignan diastereoisomers, (-)-Galbelgin, (-)-Ganschisandrin, Galgravin and (-)-Veraguensin, from Piper kadsura were separated and purified by chiral SFC. Purification strategy was designed, considering of the compound enrichment, sample purity and purification throughput...
June 12, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28641764/are-static-and-functional-balance-abilities-related-in-individuals-with-multiple-sclerosis
#10
Massimiliano Pau, Micaela Porta, Giancarlo Coghe, Federica Corona, Giuseppina Pilloni, Lorena Lorefice, Maria Giovanna Marrosu, Eleonora Cocco
BACKGROUND: In people with Multiple Sclerosis (pwMS), balance assessment is essential in estimating the risk of falls, monitoring disease progression and verifying the effectiveness of rehabilitative treatment. Clinical tools and instrumental techniques are available for testing static and dynamic balance, but the relationship between such abilities is still not clear. Having information about this link would be important in properly planning the type and number of tests to administer...
July 2017: Multiple Sclerosis and related Disorders
https://www.readbyqxmd.com/read/28641543/zein-based-nanocarriers-as-potential-natural-alternatives-for-drug-and-gene-delivery-focus-on-cancer-therapy
#11
Ahmed Elzoghby, May Freag, Hadeer Mamdouh, Kadria Elkhodairy
Protein nanocarriers possess unique merits including minimal cytotoxicity, numerous renewable sources, and high drug-binding capability. In opposition to delivery carriers utilizing hydrophilic animal proteins, hydrophobic plant proteins (e.g, zein) have great tendency in fabricating controlled-release particulate carriers without additional chemical modification to stiffen them, which in turn evades the use of toxic chemical crosslinkers. Moreover, zein is related to a class of alcohol-soluble prolamins and generally recognized as safe (GRAS) carrier for drug delivery...
June 22, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28641466/a-model-of-lipid-rearrangements-during-pore-formation-in-the-dppc-lipid-bilayer
#12
Artur Wrona, Krystian Kubica
CONTEXT: The molecular bases of pore formation in the lipid bilayer remain unclear, as do the exact characteristics of their sizes and distributions. To understand this process, numerous studies have been performed on model lipid membranes including cell-sized giant unilamellar vesicles (GUV). The effect of an electric field on DPPC GUV depends on the lipid membrane state: in the liquid crystalline phase the created pores have a cylinder-like shape, whereas in the gel phase a crack has been observed...
June 23, 2017: Journal of Liposome Research
https://www.readbyqxmd.com/read/28641441/the-closo-si12c12-molecule-from-cluster-to-crystal-effects-of-hydrogenation-and-oligomerization-on-excited-states
#13
Xiaofeng F Duan, Larry W Burggraf
Excited state properties of chain and cyclic oligomers of closo-Si12C12 moieties are calculated using time-dependent density functional theory methods. Ultraviolet, visible, and near-infrared photo-absorption properties are described for oligomers that form by linking closo-Si12C12 monomer moieties through Si-Si bonds. Natural transition orbitals for electron and hole states of stationary-state excitons in oligomers were compared to understand how exciton states are influenced by oligomer structure. Depending on the structure, some prominent excited states have large electron-hole charge separation while others do not; some exhibit exciton delocalization while others do not...
June 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28641428/liquid-liquid-phase-transition-in-an-ionic-model-of-silica
#14
Renjie Chen, Erik Lascaris, Jeremy C Palmer
Recent equation of state calculations [E. Lascaris, Phys. Rev. Lett. 116, 125701 (2016)] for an ionic model of silica suggest that it undergoes a density-driven, liquid-liquid phase transition (LLPT) similar to the controversial transition hypothesized to exist in deeply supercooled water. Here, we perform extensive free energy calculations to scrutinize the model's low-temperature phase behavior and confirm the existence of a first-order phase transition between two liquids with identical compositions but different densities...
June 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28641406/novel-antimicrobial-activities-of-a-peptide-derived-from-a-japanese-soybean-fermented-food-natto-against-streptococcus-pneumoniae-and-bacillus-subtilis-group-strains
#15
Manabu Kitagawa, Tsukasa Shiraishi, Soh Yamamoto, Ryosuke Kutomi, Yasuo Ohkoshi, Toyotaka Sato, Hideki Wakui, Hideaki Itoh, Atsushi Miyamoto, Shin-Ichi Yokota
We recently isolated a tumoricidal peptide from Natto, a Japanese traditional fermented food. In the present study, antimicrobial activity of the Natto peptide was examined. The peptide consisted of 45 amino acid residues, and its structure was predicted to be rich in α-helix. It excreted antimicrobial activity only against Streptococcus pneumoniae and Bacillus subtilis group (B. subtilis, Bacillus pumilus, and Bacillus licheniformis). Lesser antimicrobial activity was observed for Streptococcus species other than S...
December 2017: AMB Express
https://www.readbyqxmd.com/read/28640955/in-solution-antibody-harvesting-with-a-plant-produced-hydrophobin-protein-a-fusion
#16
Katri Kurppa, Lauri Reuter, Anneli Ritala, Markus Linder, Jussi Joensuu
Purification is a bottleneck and a major cost factor in the production of antibodies. We set out to engineer a bi-functional fusion protein from two building blocks, Protein A and a hydrophobin, aiming at low-cost and scalable antibody capturing in solutions. Immunoglobulin-binding Protein A is widely used in affinity-based purification. The hydrophobin fusion tag, on the other hand, has been shown to enable purification by two-phase separation. Protein A was fused to two different hydrophobin tags, HFBI or II, and expressed transiently in Nicotiana benthamiana...
June 22, 2017: Plant Biotechnology Journal
https://www.readbyqxmd.com/read/28640603/changes-in-light-absorptivity-of-molecular-weight-separated-brown-carbon-due-to-photolytic-aging
#17
Jenny Pui Shan Wong, Athanasios Nenes, Rodney J Weber
Brown carbon (BrC) are those organic compounds in atmospheric aerosols that absorb solar radiation and may play an important role on planetary radiative forcing and climate. However, little is known about the production and loss mechanisms of BrC in the atmosphere. Here, we study how the light absorptivity of BrC from wood smoke and secondary BrC generated from reaction of ammonium sulfate with methylglyoxal changes under photolytic aging by UVA radiation in the aqueous phase. Owing to its chemical complexity, BrC is separated by molecular weight using size exclusion chromatography and the response of each molecular weight fraction to aging is studied...
June 22, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28640585/thermally-and-electrically-triggered-triple-shape-memory-behavior-of-poly-vinyl-acetate-poly-lactic-acid-due-to-graphene-induced-phase-separation
#18
Mohammad Sabzi, Masoud Babaahmadi, Mohammadreza Rahnama
This work aimed to develop a facile and broadly applicable method for fabricating a multi-stimuli responsive triple-shape memory polymer (SMP). Hence, herein the SMPs were prepared through the simple physical blending of two commercially available biopolymers, poly(lactic acid) (PLA) and poly(vinyl acetate) (PVAc), in the presence of robust and conductive graphene nanoplatelets. Interestingly, atomic force microscopy (AFM) observations and thermal analyses revealed that the presence of nanofillers led to phase separation and appearance of two well-separated transition temperatures in the blend of these two miscible polymers...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28639647/water-mediated-proton-conduction-in-a-sulfonated-microporous-organic-polymer
#19
C Klumpen, S Gödrich, G Papastavrou, J Senker
Polymer membranes (PEMs) within fuel cells (FCs) act as separators and efficient proton conducting electrolytes. Established systems tend to microphase separation into hydrophilic and hydrophobic regions, making these materials prone to water loss at elevated temperatures. Therefore, recent approaches utilize porous materials, which promise stronger interactions between water molecules and the framework, while still providing efficient conductive pathways. Here we show, that the microporous polymer PAF-1 exhibits proton conductivities up to 10(-1) S cm(-1) under hydrous conditions, after post-synthetic sulfonation...
June 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28639381/elastin-like-polypeptide-switches-a-design-strategy-to-detect-multimeric-proteins
#20
Jugal Dhandhukia, Dab Brill, Aida Kouhi, Martha Pastuszka, John Andrew MacKay
Elastin-Like Polypeptides (ELPs) reversibly phase separate in response to changes in temperature, pressure, concentration, pH, and ionic species. While powerful triggers, biological microenvironments present a multitude of more specific biological cues, such as antibodies, cytokines, and cell-surface receptors. To develop better biosensors and bioresponsive drug carriers, rational strategies are required to sense and respond to these target proteins. We recently reported that non-covalent association of two ELP fusion proteins to a 'chemical inducer of dimerization' small molecule (1...
June 22, 2017: Protein Science: a Publication of the Protein Society
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