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排序方式: 共有378条查询结果,搜索用时 15 毫秒
371.
Edna Bode Antje K. Heinrich Merle Hirschmann Desalegne Abebew Yan‐Ni Shi Tien Duy Vo Frank Wesche Yi‐Ming Shi Peter Grün Svenja Simonyi Nadine Keller Yvonne Engel Sebastian Wenski Reuel Bennet Sophie Beyer Iris Bischoff Anthony Buaya Sophie Brandt Ibrahim Cakmak Harun imen Simone Eckstein Denia Frank Robert Fürst Martin Gand Gerd Geisslinger Selcuk Hazir Marina Henke Ralf Heermann Virginie Lecaudey Wilhelm Schfer Susanne Schiffmann Anja Schüffler Rebecca Schwenk Marisa Skaljac Eckhard Thines Marco Thines Thomas Ulshfer Andreas Vilcinskas Thomas A. Wichelhaus Helge B. Bode 《Angewandte Chemie (International ed. in English)》2019,58(52):19114-19114
372.
Vo TD Himmelsbach M Haunschmidt M Buchberger W Schwarzinger C Klampfl CW 《Journal of chromatography. A》2008,1213(1):83-87
An improved method based on capillary zone electrophoresis (CZE) coupled to either ion-trap (IT) mass spectrometry (MS) or quadrupole-time-of-flight (Q-TOF) MS for the analysis of melamine-formaldehyde condensates is presented. Employing a formic acid-based electrolyte containing 50% acetonitrile (ACN) and MS detection up to 13 compounds could be determined in lab-made resins, synthesized by mixing formaldehyde and melamine in different ratios ranging from 1:1.5 to 1:4. The use of a Q-TOF-MS for detection allowed the assignment of molecular formulas for all 13 substances with high accuracy. 相似文献
373.
Beyer J Vo TN Gerostamoulos D Drummer OH 《Analytical and bioanalytical chemistry》2011,400(1):189-196
Detection of the alcohol metabolites ethylglucuronide (EtG) and ethylsulfate (EtS) has become routine in many forensic laboratories
over the last few years. Most previously published methods using liquid chromatography coupled with electrospray tandem mass
spectrometry require a post-chromatographic addition of solvent and/or extensive sample preparation prior to analysis. The
aim of the study was to develop a simplified method. To 20 μL urine, internal standard containing EtG-d5 and EtS-d
5
was added and the mixture was treated with elution buffer internal standard. EtG and EtS were separated using a Shimadzu
Prominence high performance liquid chromatography (HPLC) system with a C18 separation column (Restek Ultra Aqueous C18, 4.6 × 150 mm,
5 μm), using isocratic elution with a mobile phase consisting of 10 mM ammonium acetate buffer pH 7 (total run time, 6 min).
The compounds were detected using an Applied Biosystems API 5000 liquid chromatography tandem mass spectrometry system (atmospheric
pressure chemical ionization, multiple-reaction monitoring mode). The method was fully validated according to international
guidelines. The assay was found to be selective for the compounds of interest. It was linear from 0.1 to 10 mg/L for all analytes
(R
2 > 0.99). Matrix effects studies showed the presence of a slight but consistent ion enhancement (n = 10 different urine samples) at low concentrations and no effects at higher concentrations. Accuracy data were between 0.75%
and 8.1% bias for EtG and between −5.0% and −11.3% bias for EtS. Precision data were between 4.3% and 6.9% relative standard
deviations (RSD) for EtG and between 6.0% and 7.5% RSD for EtS. No instability was observed after repeated freezing and thawing.
This fast, reliable, and accurate method enables the detection and quantification of alcohol metabolites in urine. The method
is easier to use and more sensitive than previously published methods. 相似文献
374.
Dr. Nicolas Panel Dr. Duc Duy Vo Nour Aldin Kahlous Dr. Harald Hübner Dr. Stephanie Tiedt Dr. Pierre Matricon Dr. Jody Pacalon Dr. Oliver Fleetwood Dr. Stefanie Kampen Andreas Luttens Dr. Lucie Delemotte Prof. Jan Kihlberg Prof. Peter Gmeiner Prof. Jens Carlsson 《Angewandte Chemie (International ed. in English)》2023,62(22):e202218959
G-protein-coupled receptors (GPCRs) play important roles in physiological processes and are modulated by drugs that either activate or block signaling. Rational design of the pharmacological efficacy profiles of GPCR ligands could enable the development of more efficient drugs, but is challenging even if high-resolution receptor structures are available. We performed molecular dynamics simulations of the β2 adrenergic receptor in active and inactive conformations to assess if binding free energy calculations can predict differences in ligand efficacy for closely related compounds. Previously identified ligands were successfully classified into groups with comparable efficacy profiles based on the calculated shift in ligand affinity upon activation. A series of ligands were then predicted and synthesized, leading to the discovery of partial agonists with nanomolar potencies and novel scaffolds. Our results demonstrate that free energy simulations enable design of ligand efficacy and the same approach can be applied to other GPCR drug targets. 相似文献
375.
Dorota Turoňová Lenka Kujovská Krčmová Milan Vošmik Bohuslav Melichar František Švec 《Journal of separation science》2023,46(19):2300392
Challenges and pitfalls in the application of diethyldithiocarbamate derivatization for LC analysis of cisplatin and oxaliplatin, as well as the suitability of this method for different biological matrices with implications for use in routine practice have been identified. The LC of platinum drugs presents a significant challenge. They are polar compounds with poor retention on reverse phase packings. Cisplatin also exhibits poor absorption in UV and ionization in mass spectrometry. Therefore, we developed and optimized a derivatization approach for the LC analysis of total platinum in plasma, plasma ultrafiltrate, peritoneal fluid, and urine. Derivatization in urine proved to be difficult due to the complexity of the matrix, and extended testing was required. Our results highlight the important issues affecting the efficiency, reliability, and suitability of platinum drug derivatization. Although precolumn derivatization is less selective than its postcolumn counterpart, the application of precolumn derivatization is a simple, rapid, and universal approach for the determination of platinum drugs by HPLC. One of its major advantages is that it allows a more affordable analysis using UV detection without the need for additional high-end instrumentation such as a MS detector. 相似文献
376.
Keke Hu Kim Long Le Vo Amir Hatamie Andrew G. Ewing 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202113406
Understanding the regulatory mechanisms of exocytosis is essential for uncovering the pathologies of neuronal disorders and developing related pharmaceuticals. In this work intracellular vesicle impact electrochemical cytometry (IVIEC) measurements with different-sized (50–500 nm radius) open carbon nanopipettes (CNPs) were performed to quantify the vesicular content and release kinetics of specific vesicle populations grouped by orifice sizes. Intracellular vesicles with radius below 100 nm were captured and narrowed between 50 and 100 nm. On the basis of this, single vesicular catecholamine concentrations in the intracellular environment were quantified as 0.23–1.1 M. Our results with L-3,4-dihydroxyphenylalanine (L-DOPA)-exposure indicate that L-DOPA regulates exocytosis by increasing the dense core size and vesicular content while catecholamine concentrations did not show obvious alterations. These were all achieved simultaneously and relatively noninvasively with open CNPs. 相似文献
377.
Dr. Yetsedaw A. Tsegaw Dr. Hongmin Li Prof. em. Dr. Dr. h. c. Lester Andrews Prof. Dr. Han-Gook Cho Patrick Voßnacker Dr. Helmut Beckers Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103142
An investigation of pulsed-laser-ablated Zn, Cd and Hg metal atom reactions with HCN under excess argon during co-deposition with laser-ablated Hg atoms from a dental amalgam target also provided Hg emissions capable of photoionization of the CN photo-dissociation product. A new band at 1933.4 cm−1 in the region of the CN and CN+ gas-phase fundamental absorptions that appeared upon annealing the matrix to 20 K after sample deposition, and disappeared upon UV photolysis is assigned to (Ar)nCN+, our key finding. It is not possible to determine the n coefficient exactly, but structure calculations suggest that one, two, three or four argon atoms can solvate the CN+ cation in an argon matrix with C−N absorptions calculated (B3LYP) to be between 2317.2 and 2319.8 cm−1. Similar bands were observed in solid krypton at 1920.5, in solid xenon at 1935.4 and in solid neon at 1947.8 cm−1. H13CN reagent gave an 1892.3 absorption with shift instead, and a 12/13 isotopic frequency ratio–nearly the same as found for 13CN+ itself in the gas phase and in the argon matrix. The CN+ molecular ion serves as a useful infrared probe to examine Ng clusters. The following ion reactions are believed to occur here: the first step upon sample deposition is assisted by a focused pulsed YAG laser, and the second step occurs on sample annealing: (Ar)2++CN→Ar+CN+→(Ar)nCN+. 相似文献
378.
Patrick Pröhm Willi R. Berg Susanne M. Rupf Patrick Voßnacker Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17676-17681
A systematic study of halogenate(I/III) anions with polyatomic ligands is presented. The bis(perfluoro-tert-butoxy) halogenates(I) [X(OC4F9)2]−, X=Cl, Br, I, of chlorine, bromine, and iodine are prepared as their tetraethylammonium salts and characterized with IR, Raman, and NMR spectroscopic methods, as well as single-crystal X-ray diffraction analyses. Spectroscopical data are supported by quantum-chemical calculations. Additionally, the bonding situation of the species in question are analyzed and discussed. Furthermore, the oxidation to the corresponding halogenate(III) derivatives was studied. For [Br(OC4F9)2]−, oxidation with elemental fluorine gave [BrF2(OC4F9)2]−. Iodide was directly oxidized by ClOC4F9 to the IIII species [I(OC4F9)4]−, which is a surprisingly inert anion that might be used as a weakly coordinating anion (WCA) in the future. For [Cl(OC4F9)2]−, the decomposition products of the synthetic approaches towards a chlorine(III) system were analyzed. 相似文献