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51.
52.
In an attempt to gain further information on a stereo-structural model for activity of prostaglandins,2 we undertook the synthesis of a number of new analogues.3 In particular, 17,17-dimethyl-F2α was chosen as a good test of the “hairpin” conformation because the two 17-methyl groups would prevent side chain alignment in the particular sense of the “hairpin” model.4 相似文献
53.
Andreas Klitgaard Anita Iversen Mikael R. Andersen Thomas O. Larsen Jens Christian Frisvad Kristian Fog Nielsen 《Analytical and bioanalytical chemistry》2014,406(7):1933-1943
In natural-product drug discovery, finding new compounds is the main task, and thus fast dereplication of known compounds is essential. This is usually performed by manual liquid chromatography-ultraviolet (LC-UV) or visible light-mass spectroscopy (Vis-MS) interpretation of detected peaks, often assisted by automated identification of previously identified compounds. We used a 15 min high-performance liquid chromatography–diode array detection (UHPLC–DAD)–high-resolution MS method (electrospray ionization (ESI)+ or ESI?), followed by 10–60 s of automated data analysis for up to 3000 relevant elemental compositions. By overlaying automatically generated extracted-ion chromatograms from detected compounds on the base peak chromatogram, all major potentially novel peaks could be visualized. Peaks corresponding to compounds available as reference standards, previously identified compounds, and major contaminants from solvents, media, filters etc. were labeled to differentiate these from compounds only identified by elemental composition. This enabled fast manual evaluation of both known peaks and potential novel-compound peaks, by manual verification of: the adduct pattern, UV–Vis, retention time compared with log D, co-identified biosynthetic related compounds, and elution order. System performance, including adduct patterns, in-source fragmentation, and ion-cooler bias, was investigated on reference standards, and the overall method was used on extracts of Aspergillus carbonarius and Penicillium melanoconidium, revealing new nitrogen-containing biomarkers for both species. 相似文献
54.
S. Greilich L. Grzanka N. Bassler C.E. Andersen O. J?kel 《Radiation measurements》2010,45(10):1406-1409
We present an open-source code library for amorphous track modelling which is suppose to faciliate the application and numerical comparability as well as serve as a frame-work for the implementation of new models. We show an example of using the library indicating the choice of submodels has a significant impact on the modelling outcome. 相似文献
55.
Ditte C. Andersen Ida Skovrind Marlene Louise Christensen Charlotte H. Jensen Søren P. Sheikh 《Analytical and bioanalytical chemistry》2013,405(29):9585-9591
Stem cell therapy has opened up the possibility of treating numerous degenerating diseases. However, we are still merely at the stage of identifying appropriate sources of stem cells and exploring their full differentiation potential. Thus, tracking the stem cells upon in vivo engraftment and during in vitro co-culture is very important and is an area of research embracing many pitfalls. 5-Ethynyl-2′-deoxyuridine (EdU), a rather new thymidine analog incorporated into DNA, has recently been suggested to be a novel highly valid alternative to other dyes for labeling of stem cells and subsequent tracing of their proliferation and differentiation ability. However, our results herein do not at any stage support this recommendation, since EdU severely reduces the viability of stem cells. Accordingly, we found that transplanted EdU-labeled stem cells hardly survive upon in vivo transplantation into regenerating muscle, whereas stem cells labeled in parallel with another dye survived very well and also participated in myofiber formation. Similar data were obtained upon in vitro myogenic culture, and further analysis showed that EdU reduced cell numbers by up to 88 % and increased the cell volume of remaining cells by as much as 91 %. Even at low EdU concentrations, cell survival and phenotype were substantially compromised, and the myogenic differentiation potential was inhibited. Since we examined both primary derived cells and cell lines from several species with the same result, this appears to be a common trait of EdU. We therefore suggest that EdU labeling should be avoided (or used with precaution) for stem cell tracing purposes. Figure
Myoblasts were marked with DiI (red) and EdU (purple), and injected into lesioned skeletal muscle. At day 9 following transplantation, only DiI positive cells were observed and had participated in myofibre formation as (indicated by arrowheads) visualized by red fluorescence signals inside laminin (green) positive multinucleated myofibres. EdU was toxic to the engrafted cells, suggesting that this reagent is non-applicaple for tracing of stem cells. 相似文献
56.
Marie Kjærgaard Bjørk Kirsten Wiese Simonsen David Wederkinck Andersen Petur Weihe Dalsgaard Stella Rögn Sigurðardóttir Kristian Linnet Brian Schou Rasmussen 《Analytical and bioanalytical chemistry》2013,405(8):2607-2617
An efficient method for analyzing illegal and medicinal drugs in whole blood using fully automated sample preparation and short ultra-high-performance liquid chromatography–tandem mass spectrometry (MS/MS) run time is presented. A selection of 31 drugs, including amphetamines, cocaine, opioids, and benzodiazepines, was used. In order to increase the efficiency of routine analysis, a robotic system based on automated liquid handling and capable of handling all unit operation for sample preparation was built on a Freedom Evo 200 platform with several add-ons from Tecan and third-party vendors. Solid-phase extraction was performed using Strata X-C plates. Extraction time for 96 samples was less than 3 h. Chromatography was performed using an ACQUITY UPLC system (Waters Corporation, Milford, USA). Analytes were separated on a 100 mm?×?2.1 mm, 1.7 μm Acquity UPLC CSH C18 column using a 6.5 min 0.1 % ammonia (25 %) in water/0.1 % ammonia (25 %) in methanol gradient and quantified by MS/MS (Waters Quattro Premier XE) in multiple-reaction monitoring mode. Full validation, including linearity, precision and trueness, matrix effect, ion suppression/enhancement of co-eluting analytes, recovery, and specificity, was performed. The method was employed successfully in the laboratory and used for routine analysis of forensic material. In combination with tetrahydrocannabinol analysis, the method covered 96 % of cases involving driving under the influence of drugs. The manual labor involved in preparing blood samples, solvents, etc., was reduced to a half an hour per batch. The automated sample preparation setup also minimized human exposure to hazardous materials, provided highly improved ergonomics, and eliminated manual pipetting. Figure
Robotic setup for fully automated solid-phase extraction of whole blood 相似文献
57.
Development of an automated dual‐mode supercritical fluid chromatography and reversed‐phase liquid chromatography mass‐directed purification system for small‐molecule drug discovery
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Kanaka Hettiarachchi May Kong Andersen Yun John R. Jacobsen Qifeng Xue 《Journal of separation science》2014,37(7):775-781
We report the development of a dual‐mode mass‐directed supercritical fluid chromatography and reversed‐phase liquid chromatography purification system. The addition of a third pump allows for flexible mobile phase control between the two techniques, and enables operation of either chromatography mode within minutes by activation of a set of switching valves on a single system. Software control, fluidic pathways, interface to the mass spectrometer, and fraction collection have been modified for compatibility between both separation methods. The conditioning solvent and tuning parameters for the mass spectrometer were adjusted to achieve an ideal signal trace in either mode with good linearity (r2 > 0.970) over a range of concentrations and minimal noise for accurate peak detection and isolation. The registration success rate is 90% and overall sample recovery for either technique is 80?90%. Combining two orthogonal separation and purification modes in one single system has improved the purification throughput of complex mixtures and has been a valuable, cost‐saving tool in our laboratory. 相似文献
58.
Maj-Britt Schmidt Andersen Mette Kristensen Claudine Manach Estelle Pujos-Guillot Sanne Kellebjerg Poulsen Thomas Meinert Larsen Arne Astrup Lars Dragsted 《Analytical and bioanalytical chemistry》2014,406(7):1829-1844
While metabolomics is increasingly used to investigate the food metabolome and identify new markers of food exposure, limited attention has been given to the validation of such markers. The main objectives of the present study were to (1) discover potential food exposure markers (PEMs) for a range of plant foods in a study setting with a mixed dietary background and (2) validate PEMs found in a previous meal study. Three-day weighed dietary records and 24-h urine samples were collected three times during a 6-month parallel intervention study from 107 subjects randomized to two distinct dietary patterns. An untargeted UPLC-qTOF-MS metabolomics analysis was performed on the urine samples, and all features detected underwent strict data analyses, including an iterative paired t test and sensitivity and specificity analyses for foods. A total of 22 unique PEMs were identified that covered 7 out of 40 investigated food groups (strawberry, cabbages, beetroot, walnut, citrus, green beans and chocolate). The PEMs reflected foods with a distinct composition rather than foods eaten more frequently or in larger amounts. We found that 23 % of the PEMs found in a previous meal study were also valid in the present intervention study. The study demonstrates that it is possible to discover and validate PEMs for several foods and food classes in an intervention study with a mixed dietary background, despite the large variability in such a dataset. Final validation of PEMs for intake of foods should be performed by quantitative analysis. Figure
Examples of two urinary exposure markers for cabbage (left) and beetroot (right) found in the study from an untargeted LC‐MS metabolomics analysis of urine samples and self‐reported food intake data 相似文献
59.
Priyanka Michael Espen Hansen Johan Isaksson Jeanette H. Andersen 《Natural product research》2020,34(14):2059-2064
AbstractThe new guanidine alkaloid Dendrobeaniamine A (1) was isolated from the organic extract of the Arctic marine bryozoan Dendrobeania murrayana. The chemical structure of 1 was elucidated by spectroscopic experiments, including 1D and 2D NMR and HRESIMS analysis. Compound 1 is a lipoamino acid, consisting of a C12 fatty acid anchored to the amino acid arginine. The bioactivity of 1 was evaluated using cellular and biochemical assays, but the compound did not show cytotoxic, antimicrobial, anti-inflammatory or antioxidant activities 相似文献
60.
Stephan Christgau Jette Odderhede Kenny Stahl Jens E. T. Andersen 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):m259-m262
[Sr(C5H7NO4)]·6H2O, (I), and [Sr(C5H8NO4)2]·5H2O, (II), both crystallize with similar strontium–glutamate–water layers. In (I), the neutral layers are connected through hydrogen bonds by water molecules, while in (II), the positively charged layers are connected through hydrogen bonds and electrostatic interactions by interleaving layers of hydrogen glutamate anions and water molecules. 相似文献