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Kristen Healy
The goal of this study was to evaluate the use of stable isotope labeled compounds to better understand factors influencing energy turnover in larval Culex quinquefasciatus (Say; Diptera: Culicidae). Three isotope labeled compounds were evaluated in this study, including 15N-labeled potassium nitrate, 13C-labeled glucose, and 13C-labeled leucine. Conditions were first optimized in the laboratory to determine the most appropriate concentration of isotope, as well as the half-life of enrichment. Once optimum conditions were established we used standard equations to predict and determine temperature and density-dependent energy turnover rates...
March 14, 2018: Journal of Medical Entomology
Julian C Berengut, Dmitry Budker, Cédric Delaunay, Victor V Flambaum, Claudia Frugiuele, Elina Fuchs, Christophe Grojean, Roni Harnik, Roee Ozeri, Gilad Perez, Yotam Soreq
We explore a method to probe new long- and intermediate-range interactions using precision atomic isotope shift spectroscopy. We develop a formalism to interpret linear King plots as bounds on new physics with minimal theory inputs. We focus only on bounding the new physics contributions that can be calculated independently of the standard model nuclear effects. We apply our method to existing Ca^{+} data and project its sensitivity to conjectured new bosons with spin-independent couplings to the electron and the neutron using narrow transitions in other atoms and ions, specifically, Sr and Yb...
March 2, 2018: Physical Review Letters
Debasis Banerjee, Xianyin Chen, Sergey Lobanov, Anna M Plonka, Xiaojun Chan, John Daly, Taejin Kim, Praveen K Thallapally, John Parise
Used nuclear fuel reprocessing represents a unique challenge when dealing with radionuclides such as isotopes of85 Kr and129 I2 due to their volatility and long half-life. Efficient capture of129 I2 (t1/2 = 15.7 ×106 million years) from the nuclear waste stream can help reduce the risk of releasing I2 radionuclide into the environment and/or potential incorporation into the human thyroid. Metal organic frameworks have the reported potential to be I2 adsorbents but the effect of water vapor, generally present in the reprocessing off-gas stream, is rarely taken into account...
March 16, 2018: ACS Applied Materials & Interfaces
Ling-Zhen Cao, Xiao-Wei Fu, Chao-Xing Hu, Kong-Ming Wu
Pantala flavescens (Fabricius 1798) (Odonata: Libellulidae) is one of the most common species of migratory dragonflies. P. flavescens adults were captured by a searchlight trap on Beihuang Island (BH Island; 38°24'N, 120°55'E) from 2003 to 2016, where there is no freshwater. This inspired our research to analyze the pattern of seasonal migration and population dynamics. Stable hydrogen isotope measurement and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) were used to simulate the migration pathway of P...
March 12, 2018: Environmental Entomology
Heike Bittersohl, Björn Schniedewind, Uwe Christians, Peter B Luppa
Therapeutic drug monitoring (TDM) of the immunosuppressive drug tacrolimus is essential to avoid side effects and rejection of the allograft after transplantation. In the blood circulation, tacrolimus is largely located inside erythrocytes or bound to plasma proteins and less than 0.1% is protein-unbound (free). One basic principle of clinical pharmacology is that only free drug is pharmacologically active and monitoring this portion has the potential to better reflect the drug effect than conventional measurements of total tacrolimus in whole blood...
March 7, 2018: Journal of Chromatography. A
Oliver C C Paine, Abigale Koppa, Amanda G Henry, Jennifer N Leichliter, Daryl Codron, Jacqueline Codron, Joanna E Lambert, Matt Sponheimer
Discussions about early hominin diets have generally excluded grass leaves as a staple food resource, despite their ubiquity in most early hominin habitats. In particular, stable carbon isotope studies have shown a prevalent C4 component in the diets of most taxa, and grass leaves are the single most abundant C4 resource in African savannas. Grass leaves are typically portrayed as having little nutritional value (e.g., low in protein and high in fiber) for hominins lacking specialized digestive systems. It has also been argued that they present mechanical challenges (i...
April 2018: Journal of Human Evolution
Brendan Joyce, Danny Lee, Alex Rubio, Aleksey Ogurtsov, Gelio Alves, Yi-Kuo Yu
OBJECTIVE: RAId is a software package that has been actively developed for the past 10 years for computationally and visually analyzing MS/MS data. Founded on rigorous statistical methods, RAId's core program computes accurate E-values for peptides and proteins identified during database searches. Making this robust tool readily accessible for the proteomics community by developing a graphical user interface (GUI) is our main goal here. RESULTS: We have constructed a graphical user interface to facilitate the use of RAId on users' local machines...
March 15, 2018: BMC Research Notes
Masahiko Machida, Koichiro Kato, Motoyuki Shiga
The isotopologs of liquid water, H2 O, D2 O, and T2 O, are studied systematically by first principles PIMD simulations, in which the whole entity of the electrons and nuclei are treated quantum mechanically. The simulation results are in reasonable agreement with available experimental data on isotope effects, in particular, on the peak shift in the radial distributions of H2 O and D2 O and the shift in the evaporation energies. It is found that, due to differences in nuclear quantum effects, the H atoms in the OH bonds more easily access the dissociative region up to the hydrogen bond center than the D (T) atoms in the OD (OT) bonds...
March 14, 2018: Journal of Chemical Physics
E Curotto, M Mella
We have computed ground state energies and analyzed radial distributions for several gas phase and adsorbed D2 (H2 )n and HD(H2 )n clusters. An external model potential designed to mimic ionic adsorption sites inside porous materials is used [M. Mella and E. Curotto, J. Phys. Chem. A 121, 5005 (2017)]. The isotopic substitution lowers the ground state energies by the expected amount based on the mass differences when these are compared with the energies of the pure clusters in the gas phase. A similar impact is found for adsorbed aggregates...
March 14, 2018: Journal of Chemical Physics
Yang Xu, Kai Song, Qiang Shi
The hydride transfer reaction catalyzed by dihydrofolate reductase is studied using a recently developed mixed quantum-classical method to investigate the nuclear quantum effects on the reaction. Molecular dynamics simulation is first performed based on a two-state empirical valence bond potential to map the atomistic model to an effective double-well potential coupled to a harmonic bath. In the mixed quantum-classical simulation, the hydride degree of freedom is quantized, and the effective harmonic oscillator modes are treated classically...
March 14, 2018: Journal of Chemical Physics
Pablo E Videla, Peter J Rossky, D Laria
We present a path-integral-molecular-dynamics study of the thermodynamic stabilities of DOH⋯ X- and HOD⋯ X- (X = F, Cl, Br, I) coordination in aqueous solutions at ambient conditions. In agreement with experimental evidence, our results for the F- case reveal a clear stabilization of the latter motif, whereas, in the rest of the halogen series, the former articulation prevails. The DOH⋯ X- preference becomes more marked the larger the size of the ionic solute. A physical interpretation of these tendencies is provided in terms of an analysis of the global quantum kinetic energies of the light atoms and their geometrical decomposition...
March 14, 2018: Journal of Chemical Physics
Massimo Boninsegni
The momentum distribution and atomic kinetic energy of the two isotopes of helium in a liquid mixture at temperature T = 2 K are computed by quantum Monte Carlo simulations. Quantum statistics is fully included for4 He, whereas3 He atoms are treated as distinguishable. Comparison of theoretical estimates with a collection of the most recent experimental measurements shows reasonable agreement for the energetics of4 He and pure3 He. On the other hand, a significant discrepancy (already observed in previous studies) is reported between computed and measured values of the3 He kinetic energy in the mixture, especially in the limit of low3 He concentration...
March 14, 2018: Journal of Chemical Physics
Evelina Cardoso, Thomas Mercier, Anna Dorothea Wagner, Krisztian Homicsko, Olivier Michielin, Kim Ellefsen-Lavoie, Laurène Cagnon, Manuel Diezi, Thierry Buclin, Nicolas Widmer, Chantal Csajka, Laurent Decosterd
A sensitive and selective method of high performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS/MS) has been developed for the simultaneous quantification of six anticancer protein kinase inhibitors (PKIs), dabrafenib, trametinib, vemurafenib, cobimetinib, pazopanib, regorafenib, and two active metabolites (regorafenib-M2 and regorafenib-M5) in human plasma. Plasma protein precipitation with methanol enables the sample extraction of 100 μL aliquot of plasma. Analytes are detected by electrospray triple-stage quadrupole mass spectrometry and quantified using the calibration curves with stable isotope-labeled internal standards...
February 8, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Heejung Kim, Dugin Kaown, Bernhard Mayer, Jin-Yong Lee, Kang-Kun Lee
Hyporheic zones are considered hot spots for numerically vast and phylogenetically diverse microbial communities. However, biogeochemical effects of hyporheic zones have rarely been investigated in detail because of the difficulty in accurately measuring denitrification in these zones. To date, little is known about the hydroecology of hyporheic zones. The effect of changes in hydraulic conditions on the community variations of indigenous microorganisms and water quality was examined based on the depth of the hyporheic zone...
March 12, 2018: Science of the Total Environment
John K Fallon, Nicole Houvig, Catherine L Booth-Genthe, Philip C Smith
Information is needed on the expression of transporters in lung to inform drug development and therapeutic decisions. Much of the information currently available is from semiquantitative gene expression or immunometric densitometry studies reported in the literature. NanoLC-MS/MS (MRM mode) isotope dilution targeted quantitative proteomics was used here to quantify twelve selected transporters in fresh human lung membrane fraction samples and in the membrane fraction of selected immortalized human lung epithelial cell line samples...
February 22, 2018: Journal of Pharmaceutical and Biomedical Analysis
Li Chen, Nathchar Naowarojna, Heng Song, Shu Wang, Jianyun Wang, Zixin Deng, Changming Zhao, Pinghua Liu
Ovothiol is a histidine thiol derivative. The biosynthesis of ovothiol involves an extremely efficient trans-sulfuration strategy. The non-heme iron enzyme OvoA catalyzed oxidative coupling be-tween cysteine and histidine is one of the key steps. Besides catalyzing the oxidative coupling between cysteine and histidine, OvoA also catalyzes the oxi-dation of cysteine to cysteine sulfinic acid (cysteine dioxygenase activity). Thus far, very little mecha-nistic information is available for OvoA-catalysis. In this report, we measured the kinetic isotope effect (KIE) in OvoA-catalysis using the isotopically sensitive branching method...
March 15, 2018: Journal of the American Chemical Society
Jinxu Gao, Adelphe Mfuh, Yuka Amako, Christina M Woo
Many therapeutics elicit cell-type specific polypharmacology that is executed by a network of molecular recognition events between a small molecule and the whole proteome. However, measurement of the structures that underpin the molecular associations between the proteome and even common therapeutics, such as the nonsteroidal anti-inflammatory drugs (NSAIDs), is limited by the inability to map the small molecule interactome. To address this gap, we developed a platform termed small molecule interactome mapping by photoaffinity labeling (SIM-PAL) and applied it to the in cellulo direct characterization of specific NSAID binding sites...
March 15, 2018: Journal of the American Chemical Society
Teklab Gebregiworgis, Christopher Boyd Marshall, Tadateru Nishikawa, Nikolina Radulovich, María-José Sandi, Zhenhao Fang, Robert Rottapel, Ming-Sound Tsao, Mitsuhiko Ikura
Small GTPases (sGTPases) are critical switch-like regulators that mediate several important cellular functions and are often mutated in human cancers. They are activated by guanine nucleotide exchange factors (GEFs), which specifically catalyze the exchange of GTP for GDP. GEFs coordinate signaling networks in normal cells, and are frequently deregulated in cancers. sGTPase signaling pathways are complex and interconnected; however, most GEF assays do not reveal such complexity. In this communication, we describe the development of a unique real-time NMR-based multiplexed GEF assay that employs distinct isotopic labeling schemes for each sGTPase protein to enable simultaneous observation of six proteins of interest...
March 15, 2018: Journal of the American Chemical Society
David B Medeiros, Leonardo Perez de Souza, Werner C Antunes, Wagner L Araújo, Danilo M Daloso, Alisdair R Fernie
Sucrose has long been thought to play an osmolytic role in stomatal opening. However, recent evidence supports the idea that the role of sucrose in this process is primarily energetic. Here we used a combination of stomatal aperture assays coupled with kinetic [U-13 C]-sucrose isotope labelling experiments to confirm that sucrose is degraded during light-induced stomatal opening and to define the fate of the C released from sucrose breakdown. We additionally show that addition of sucrose in the medium did not enhance light-induced stomatal opening...
March 15, 2018: Plant Journal: for Cell and Molecular Biology
Lawrence Mj Best, Yemisi Takwoingi, Sulman Siddique, Abiram Selladurai, Akash Gandhi, Benjamin Low, Mohammad Yaghoobi, Kurinchi Selvan Gurusamy
BACKGROUND: Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain...
March 15, 2018: Cochrane Database of Systematic Reviews
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