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Contrast kinetics

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https://www.readbyqxmd.com/read/29334019/chemical-stabilization-of-polymers-implications-for-dermal-exposure-to-additives
#1
N Bartsch, M Girard, L Schneider, V Van De Weijgert, A Wilde, O Kappenstein, B Vieth, C Hutzler, A Luch
Technical benefits of additives in polymers stand in marked contrast to their associated health risks. Here, a multi-analyte method based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) was developed to quantify polymer additives in complex matrices such as low-density polyethylene (LDPE) and isolated human skin layers after dermal exposure ex vivo. That way both technical aspects and dermal exposure were investigated. The effects of polymer additivation on the material were studied using the example of LDPE...
January 15, 2018: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
https://www.readbyqxmd.com/read/29333858/mineral-and-base-catalyzed-hydrolysis-of-organophosphate-flame-retardants-a-potential-major-fate-controlling-sink-in-soil-and-aquatic-environments
#2
Yida Fang, Erin Kim, Timothy J Strathmann
The ubiquitous occurrence of organophosphate flame retardants (OPFRs) in aquatic and soil environments poses significant risks to human health and ecosystems. Here, we report on the hydrolysis of six OPFRs and three structural analogues in the absence and presence of metal (hydr)oxide minerals. Eight of the target compounds showed marked degradation in alkaline solutions (pH 9-12) with half-lives ranging from 0.02 - 170 d. Kinetics follow a second-order rate law with apparent rate constants for base-catalyzed hydrolysis (kB) ranging from 0...
January 15, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29332951/soil-seal-development-under-simulated-rainfall-structural-physical-and-hydrological-dynamics
#3
Elena Armenise, Robert W Simmons, Sujung Ahn, Amin Garbout, Stefan H Doerr, Sacha J Mooney, Craig J Sturrock, Karl Ritz
This study delivers new insights into rainfall-induced seal formation through a novel approach in the use of X-ray Computed Tomography (CT). Up to now seal and crust thickness have been directly quantified mainly through visual examination of sealed/crusted surfaces, and there has been no quantitative method to estimate this important property. X-ray CT images were quantitatively analysed to derive formal measures of seal and crust thickness. A factorial experiment was established in the laboratory using open-topped microcosms packed with soil...
January 2018: Journal of Hydrology
https://www.readbyqxmd.com/read/29330188/germination-outgrowth-and-vegetative-growth-kinetics-of-dry-heat-treated-individual-spores-of-bacillus-species
#4
Lin He, Zhan Chen, Shiwei Wang, Muying Wu, Peter Setlow, Yong-Qing Li
DNA damage kills dry-heated spores of Bacillus subtilis, but dry heat-treatment effects on spore germination and outgrowth have not been studied. This is important, since if dry heat-killed spores germinate and undergo outgrowth, toxic proteins could be synthesized. Here, Raman spectroscopy and differential interference contrast microscopy were used to study germination and outgrowth of individual dry heat-treated B. subtilis and Bacillus megaterium spores. Major findings in this work were as follows. 1) Spores dry heat-treated at 140°C for 20 min nearly all lost viability but retained their Ca2+-dipicolinic acid (CaDPA) depot...
January 12, 2018: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29329012/oxidative-transformation-kinetics-and-pathways-of-albendazole-from-reactions-with-manganese-dioxide
#5
Sin-Yi Liou, Wan-Ru Chen
Albendazole (ABZ) is a benzimidazole-based veterinary anthelmintic used extensively in the treatment of intestinal parasites. Due to its high hydrophobicity, ABZ tends to accumulate in soils and sediments in the environment. This study aims to investigate ABZ's possible degradation by manganese oxides. Minor effects from ionic strength and metal cations on ABZ degradation were observed. By contrast, decrease of pH greatly enhanced the reaction rate. Surface complexation between ABZ and MnO2 was indicated to be the dominant control in the reaction kinetics...
December 29, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29325119/mir-96-is-required-for-normal-development-of-the-auditory-hindbrain
#6
Tina Schlüter, Christina Berger, Elena Rosengauer, Pascal Fieth, Constanze Krohs, Kathy Ushakov, Karen P Steel, Karen B Avraham, Alexander Hartmann, Felix Felmy, Hans Gerd Nothwang
The peripheral deafness gene Mir96 is expressed in both the cochlea and central auditory circuits. To investigate whether it plays a role in the auditory system beyond the cochlea, we characterized homozygous Dmdo/Dmdo mice with a point mutation in miR-96. Anatomical analysis demonstrated a significant decrease in volume of auditory nuclei in Dmdo/Dmdo mice. This decrease resulted from decreased cell size. Non-auditory structures in the brainstem of Dmdo/Dmdo mice or auditory nuclei of the congenital deaf Cldn14-/- mice revealed no such differences...
January 9, 2018: Human Molecular Genetics
https://www.readbyqxmd.com/read/29324781/neuraminidase-inhibitor-susceptibility-and-neuraminidase-enzyme-kinetics-of-human-influenza-a-and-b-viruses-circulating-in-thailand-in-2010-2015
#7
Nipaporn Tewawong, Bindumadhav M Marathe, Yong Poovorawan, Sompong Vongpunsawad, Richard J Webby, Elena A Govorkova
Amino acid substitutions within or near the active site of the viral neuraminidase (NA) may affect influenza virus fitness. In influenza A(H3N2) and B viruses circulating in Thailand between 2010 and 2015, we identified several NA substitutions that were previously reported to be associated with reduced inhibition by NA inhibitors (NAIs). To study the effect of these substitutions on the enzymatic properties of NA and on virus characteristics, we generated recombinant influenza viruses possessing either a wild type (WT) NA or an NA with a single I222V, S331G, or S331R substitution [in influenza A(H3N2) viruses] or a single D342S, A395T, A395V, or A395D NA substitution (in influenza B viruses)...
2018: PloS One
https://www.readbyqxmd.com/read/29321534/mitochondrial-network-complexity-emerges-from-fission-fusion-dynamics
#8
Nahuel Zamponi, Emiliano Zamponi, Sergio A Cannas, Orlando V Billoni, Pablo R Helguera, Dante R Chialvo
Mitochondrial networks exhibit a variety of complex behaviors, including coordinated cell-wide oscillations of energy states as well as a phase transition (depolarization) in response to oxidative stress. Since functional and structural properties are often interwinded, here we characterized the structure of mitochondrial networks in mouse embryonic fibroblasts using network tools and percolation theory. Subsequently we perturbed the system either by promoting the fusion of mitochondrial segments or by inducing mitochondrial fission...
January 10, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29317433/improved-evaluation-of-antivascular-cancer-therapy-using-constrained-tracer-kinetic-modeling-for-multi-agent-dynamic-contrast-enhanced-mri
#9
Stefanie Hectors, Igor Jacobs, Jasper Lok, Johannes Peters, Johan Bussink, Freek J M Hoeben, Henk Keizer, Henk M Janssen, Klaas Nicolay, Matthias Schabel, Gustav Strijkers
Dynamic contrast-enhanced MRI (DCE-MRI) is a promising technique for assessing the response of tumor vasculature to anti-vascular therapies. Multi-agent DCE-MRI employs a combination of low and high molecular weight contrast agents, which potentially improves the accuracy of estimation of tumor hemodynamic and vascular permeability parameters. In this study, we employed multi-agent DCE-MRI to assess changes in tumor hemodynamics and vascular permeability after vascular-disrupting therapy. Multi-agent DCE-MRI (sequential injection of G5 dendrimer, G2 dendrimer, and Gd-DOTA) was performed in tumor-bearing mice before, 2 h and 24 h after treatment with vascular disrupting agent DMXAA or placebo...
January 9, 2018: Cancer Research
https://www.readbyqxmd.com/read/29316403/microsolvated-model-for-the-kinetics-and-thermodynamics-of-glycosidic-bond-dissociative-cleavage-of-nucleoside-d4g
#10
Yang Jiang, Ying Xue, Yi Zeng
Using the microsolvated model that involves explicit water molecules and implicit solvent in the optimization, two proposed dissociative hydrolysis mechanisms of 2',3'-didehydro-2',3'-dideoxyguanosine (d4G) have been firstly investigated by means of M062X(CPCM, water)/6-31++G(d,p) method. The glycosidic bond dissociation for the generation of oxacarbenium ion intermediate is the rate-determining step (RDS). The subsequent nucleophilic water attack from different side of the oxacarbenium ion intermediate gives either the α-product [(2S,5S)-5-(hydroxymethyl)-2,5-dihydrofuran-2-ol] or β-product [(2R,5S)-5-(hydroxymethyl)-2,5-dihydrofuran-2-ol], and is thus referred to as α-path (inversion) and β-path (retention)...
January 9, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29316393/reversible-and-efficient-light-induced-molecular-switching-on-an-insulator-surface
#11
Simon Jaekel, Antje Richter, Robert Lindner, Ralf Bechstein, Christophe Nacci, Stefan Hecht, Angelika Kuhnle, Leonhard Grill
Prototypical molecular switches such as azobenzenes exhibit two states, i.e. trans and cis, with different characteristic physical properties. In recent years various derivatives were investigated on metallic surfaces. However, bulk insulators as supporting substrate reveal important advantages since they allow electronic decoupling from the environment, which is key to control the switching properties. Here, we report on the light-induced isomerization of an azobenzene derivative on a bulk insulator surface, in this case calcite (101 ̅4), studied by atomic force microscopy with submolecular resolution...
January 9, 2018: ACS Nano
https://www.readbyqxmd.com/read/29314060/dynamic-field-of-view-imaging-to-increase-temporal-resolution-in-the-early-phase-of-contrast-media-uptake-in-breast-dce-mri-a-feasibility-study
#12
Federico D Pineda, Ty O Easley, Gregory S Karczmar
PURPOSE: To increase diagnostic accuracy of breast MRI by increasing temporal resolution and more accurately sampling the early kinetics of contrast media uptake. We tested the feasibility of accelerating bilateral breast DCE-MRI by reducing the FOV, allowing aliasing, and unfolding the resulting images. METHODS: Previous experience with an 'ultrafast' protocol for bilateral breast DCE-MRI (6s-10s temporal resolution) showed that the number of significantly enhancing voxels is very low in the first 30 to 45 seconds after contrast media injection...
January 3, 2018: Medical Physics
https://www.readbyqxmd.com/read/29311654/bidirectional-modulation-between-infiltrating-cd3-t-lymphocytes-and-astrocytes-in-the-spinal-cord-drives-the-development-of-allodynia-in-monoarthritic-rats
#13
Ya-Lan Zhou, Shu-Zhuan Zhou, Hao-Ling Li, Man-Li Hu, Hui Li, Qing-Huan Guo, Xiao-Ming Deng, Yu-Qiu Zhang, Hua Xu
Increasing evidence suggests that T cells and glia participate in the process of neuropathic pain. However, little is known about the involvement of T cells or the interaction between glia and T cells at the molecular level. Here we investigated the phenotype of T cell infiltration into the spinal cord in inflammatory pain and explored potential crosstalk between glia and T cells. The establishment of monoarthritis produced T cell infiltration and astrocyte activation, exhibiting similar kinetics in the spinal cord...
January 8, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29306966/efficient-synthesis-of-%C3%AE-lactam-antibiotics-with-very-low-product-hydrolysis-by-a-mutant-providencia-rettgeri-penicillin-g-acylase
#14
Xin Pan, Li Wang, Jiajie Ye, Song Qin, Bingfang He
Penicillin G acylase (PGA) was isolated from Providencia rettgeri PX04 (PrPGApx04) and utilized for the kinetically controlled synthesis of β-lactam antibiotics. Site-directed mutagenesis was performed to increase the process efficiency. Molecular docking was carried out to speculate the key mutant positions corresponding with synthetic activity, which resulted in the achievement of an efficient mutant, βF24G. It yielded higher conversions than the wild-type enzyme in the synthesis of amoxicillin (95 versus 17...
January 6, 2018: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29306199/effect-of-composting-and-soil-type-on-dissipation-of-veterinary-antibiotics-in-land-applied-manures
#15
Chaoqi Chen, Partha Ray, Katharine F Knowlton, Amy Pruden, Kang Xia
The objective of this study was to determine the fate of commonly used veterinary antibiotics in their naturally excreted form when manure-based amendments are applied to soil. Beef cattle were administered sulfamethazine, tylosin, and chlortetracycline and dairy cows were treated with pirlimycin. The resulting manure was composted for 42 d under static or turned conditions and applied at agronomic N rates to sandy, silt, and silty clay loam soils and compared with amendment with corresponding raw manures in sacrificial microcosms over a 120-day period...
December 26, 2017: Chemosphere
https://www.readbyqxmd.com/read/29305053/structure-kinetics-molecular-and-redox-properties-of-a-cytosolic-and-developmentally-regulated-fungal-catalase-peroxidase
#16
Vanessa Vega-García, Adelaida Díaz-Vilchis, Juan-Pablo Saucedo-Vázquez, Alejandro Solano-Peralta, Enrique Rudiño-Piñera, Wilhelm Hansberg
CAT-2, a cytosolic catalase-peroxidase (CP) from Neurospora crassa, which is induced during asexual spore formation, was heterologously expressed and characterized. CAT-2 had the Met-Tyr-Trp adduct required for catalase activity. Its KM for H2O2 was micromolar for peroxidase and millimolar for catalase activity. A Em = -158 mV reduction potential value was obtained and the Soret band shift suggested a mixture of low and high spin ferric iron. CAT-2 EPR spectrum at 10 K indicated an axial and a rhombic component...
January 2, 2018: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/29303258/direct-photolysis-of-sulfamethoxazole-using-various-irradiation-sources-and-wavelength-ranges-insights-from-degradation-product-analysis-and-compound-specific-stable-isotope-analysis
#17
Sarah Willach, Holger Volker Lutze, Kevin Eckey, Katja Löppenberg, Michelle Lueling, Jens-Benjamin Wolbert, Dorothea M Kujawinski, Maik A Jochmann, Uwe Karst, Torsten Claus Schmidt
The environmental micropollutant sulfamethoxazole (SMX) is susceptible to phototransformation by sunlight and UV-C light which is used for water disinfection. Depending on the environmental pH conditions SMX may be present as neutral or anionic species. This study systematically investigates the phototransformation of these two relevant SMX species using four different irradiation scenarios, i.e. a low, medium and high pressure Hg lamp and simulated sunlight. The observed phototransformation kinetics are complemented by data from compound-specific stable isotope and transformation product analysis using isotope-ratio and high-resolution mass spectrometry (HRMS)...
January 5, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29301983/insights-into-the-effect-of-minor-groove-interactions-and-metal-cofactors-on-mutagenic-replication-by-human-dna-polymerase-%C3%AE
#18
Myong-Chul Koag, Seongmin Lee
DNA polymerases accommodate various base pair conformations in the event of incorrect insertions. In particular, Watson-Crick-like dG:dTTP base pair has been observed at the insertion site of human DNA polymerase β (pol β). A potential factor contributing to the diverse conformations of base pair mismatches is minor groove interactions. To gain insight into the effect of minor groove interactions on base pair conformations, we generated an Asn279Ala polβ mutant that cannot make minor groove contacts with incoming nucleotide...
January 4, 2018: Biochemical Journal
https://www.readbyqxmd.com/read/29297692/comparison-of-the-expression-kinetics-and-immunostimulatory-activity-of-replicating-mrna-non-replicating-mrna-and-pdna-after-intradermal-electroporation-in-pigs
#19
Bregje Leyman, Hanne Huysmans, Séan Mc Cafferty, Francis Combes, Eric Cox, Bert Devriendt, Niek N Sanders
Synthetic mRNA is becoming increasingly popular as an alternative to pDNA-based gene therapy. Currently, multiple synthetic mRNA platforms have been developed. In this study we investigated the expression kinetics and the changes in mRNA encoding cytokine and chemokine levels following intradermal electroporation in pigs of pDNA, self-replicating mRNA, modified- and unmodified mRNA. The self-replicating mRNA tended to induce the highest protein expression, followed by pDNA, modified mRNA and unmodified mRNA...
January 3, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29297686/structural-and-kinetic-studies-of-intermediates-of-a-biomimetic-diiron-proton-reduction-catalyst
#20
Shihuai Wang, Alexander Aster, Mohammad Mirmohades, Reiner Lomoth, Leif Hammarström
One-electron reduction and subsequent protonation of a biomimetic proton-reduction catalyst [FeFe(μ-pdt)(CO)6] (pdt = propanedithiolate), 1, were investigated by UV-vis and IR spectroscopy on a nano- to microsecond time scale. The study aimed to provide further insight into the proton-reduction cycle of this [FeFe]-hydrogenase model complex, which with its prototypical alkyldithiolate-bridged diiron core is widely employed as a molecular, precious metal-free catalyst for sustainable H2 generation. The one-electron-reduced catalyst was obtained transiently by electron transfer from photogenerated [Ru(dmb)3]+ in the absence of proton sources or in the presence of acids (dichloro- or trichloroacetic acid or tosylic acid)...
January 3, 2018: Inorganic Chemistry
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