Listen
16 Ergebnisse
Bereich: Suchergebnisse
Publikation Determination of active ingredients in formulated plant protection products by UHPLC-UV/MS(Springer, 04.10.2022) Erdin, Yves; Schlotterbeck, Götz; Mink, ChristianThe market for plant protection products (PPPs) is one of the most regulated. With increasing regulations for registering PPPs, its requirements take more effort and more testing. Meanwhile, there is also an increasing market for illegal PPPs. While legally registered PPPs are thoroughly tested and documented, illegal PPPs are sold upfront without any testing (e.g., tox, aqua tox, eco tox). This bears additional risk for the users, the ecosystem and the public. There are many well established analytical methods and protocols to analyse soil, plant products as well as for food and beverage, but less for PPPs. Many methods need laborious sample preparation and extraction steps like QuEChERS and/or advanced mass spectrometry techniques. Here we present a method developed to identify active ingredients (AIs) which is easy to apply at relatively cheap costs and widely available instrumentation. It provides a straightforward set-up for sample preparation and analysis, without the need for elaborative sample preparation. The method validation showed sufficient linearity, repeatability and specificity to use this method for screening of samples taken from market control for counterfeit or cross contamination checks.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Automated chiral method screening. Evaluation of generated chromatographic data sets to further optimize screening efficiency(Elsevier, 10.05.2021) Freund, Ernst; Meyer, Daniel; Schneider, Nadine; Lozach, Marie-Anne; Schröder, Harald; Cinar, Catagay; Schlotterbeck, Götz; Wagner, TrixieWe set up an automated screening process to routinely test 10 chiral supercritical fluid chromatography (SFC) methods - five columns combined with two co-solvents - as part of a chiral separation lab workflow. Proprietary software tools enabled automated method screening of racemates, parallel evaluation of the resulting chromatograms for enantiomer separation and report generation. This process is largely automated and resulted in an efficient and reliable lab process with a minimum requirement for human intervention. Screenings were conducted on a test set of 756 racemates that were selected with focus on structural variation and on 2667 proprietary samples from lab routines. Statistical analysis revealed that up to 92% of the tested racemic mixtures could be successfully separated with at least one of the tested conditions of the screening. Process efficiency was further increased by identification of optimal method screening sequence, re-definition of the optimal column set and project-specific adaptations considering reduced structural variation of the analytes. This study illustrates the usefulness of consistent chromatographic data sets to accelerate and facilitate the identification of chiral methods to separate enantiomers by automated processing and statistical analysis.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Extended and Fully Automated Newborn Screening Method for Mass Spectrometry Detection(MDPI, 12/2017) Gaugler, Stephan; Rykl, Jana; Wagner, Irene; von Däniken, Tamara; Fingerhut, Ralph; Schlotterbeck, GötzA new and fully automated newborn screening method for mass spectrometry was introduced in this paper. Pathological relevant amino acids, acylcarnitines, and certain steroids are detected within 4 min per sample. Each sample is treated in an automated and standardized workflow, where a mixture of deuterated internal standards is sprayed onto the sample before extraction. All compounds showed good linearity, and intra- and inter-day variation lies within the acceptance criteria (except for aspartic acid). The described workflow decreases analysis cost and labor while improving the sample traceability towards good laboratory practice.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation GABAA receptor activity modulating piperine analogs: In vitro metabolic stability, metabolite identification, CYP450 reaction phenotyping, and protein binding(Elsevier, 12/2017) Zabela, Volha; Hettich, Timm; Schlotterbeck, Götz; Wimmer, Laurin; Mihovilovic D., Marko; Guillet, Fabrice; Belkacem, Bouaita; Shevchenko, Bénédicte; Hamburger, Matthias; Oufir, MouhssinIn a screening of natural products for allosteric modulators of GABAA receptors (γ-aminobutyric acid type A receptor), piperine was identified as a compound targeting a benzodiazepine-independent binding site. Given that piperine is also an activator of TRPV1 (transient receptor potential vanilloid type 1) receptors involved in pain signaling and thermoregulation, a series of piperine analogs were prepared in several cycles of structural optimization, with the aim of separating GABAA and TRPV1 activating properties. We here investigated the metabolism of piperine and selected analogs in view of further cycles of lead optimization. Metabolic stability of the compounds was evaluated by incubation with pooled human liver microsomes, and metabolites were analyzed by UHPLC-Q-TOF-MS. CYP450 isoenzymes involved in metabolism of compounds were identified by reaction phenotyping with Silensomes™. Unbound fraction in whole blood was determined by rapid equilibrium dialysis. Piperine was the metabolically most stable compound. Aliphatic hydroxylation, and N- and O-dealkylation were the major routes of oxidative metabolism. Piperine was exclusively metabolized by CYP1A2, whereas CYP2C9 contributed significantly in the oxidative metabolism of all analogs. Extensive binding to blood constituents was observed for all compounds.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation A UHPLC–MS/MS method for the quantification of 7α-hydroxy-4-cholesten-3-one to assist in diagnosis of bile acid malabsorption(Elsevier, 01/2017) Prost, Jean-Christophe; Brunner, Félix; Grob, Christian; Berchtold, Christian; Schlotterbeck, Götz; Bovet, Cédric; Largiadèr, Carlo R.; Fiedler, Georg Martin; Juillerat, PascalBile acids malabsorption (BAM) is encountered in numerous gastrointestinal pathologies and is a good example of a treatable cause of watery diarrhea after ileal resection. The gold standard for diagnosing BAM is the selenium homocholic acid taurine test (SeHCAT), an expensive and complex analysis. An alternative method is the quantification of 7α-hydroxy-4-cholesten-3-one (C4). Here, we present a simple, ultra high-performance liquid chromatography–tandem mass spectrometry method to measure C4 in human serum. To avoid time consuming sample preparation (e.g., derivatization, solid phase extraction), we used absorption chemistry-based extraction plates. This method demonstrates a lower limit of quantification of 5 ng/mL and is linear over a concentration range from 5 to 300 ng/mL (R2 = 0.9977). Inaccuracy and imprecision were less than 15%. The validated method is currently used for routine measurement of C4 from serum in patients to confirm BAM diagnosis.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Altered (neo-) lacto series glycolipid biosynthesis impairs α2-6 sialylation on N-glycoproteins in ovarian cancer cells(Nature, 30.03.2017) Alam, Shahidul; Anugraham, Merrina; Huang, Yen-Lin; Kohler, Reto; Hettich, Timm; Winkelbach, Katharina; Grether, Yasmin; Nunez Lopez, Monica; Khasbiullina, Nailia; Bovin, Nicolai V.; Schlotterbeck, Götz; Jacob, FrancisThe (neo-) lacto series glycosphingolipids (nsGSLs) comprise of glycan epitopes that are present as blood group antigens, act as primary receptors for human pathogens and are also increasingly associated with malignant diseases. Beta-1, 3-N-acetyl-glucosaminyl-transferase 5 (B3GNT5) is suggested as the key glycosyltransferase for the biosynthesis of nsGSLs. In this study, we investigated the impact of CRISPR-Cas9 -mediated gene disruption of B3GNT5 (∆B3GNT5) on the expression of glycosphingolipids and N-glycoproteins by utilizing immunostaining and glycomics-based PGC-UHPLC-ESI-QTOF-MS/MS profiling. ∆B3GNT5 cells lost nsGSL expression coinciding with reduction of α2-6 sialylation on N-glycoproteins. In contrast, disruption of B4GALNT1, a glycosyltransferase for ganglio series GSLs did not affect α2-6 sialylation on N-glycoproteins. We further profiled all known α2-6 sialyltransferase-encoding genes and showed that the loss of α2-6 sialylation is due to silencing of ST6GAL1 expression in ∆B3GNT5 cells. These results demonstrate that nsGSLs are part of a complex network affecting N-glycosylation in ovarian cancer cells.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Antimicrobial Polyethylene through Melt Compounding with Quaternary Ammonium Salts(Hindawi Publishing Corporation, 04/2017) Rossetti, Fernanda; Siegmann, Konstantin; Köser, Joachim; Wegner, Irene; Keskin, Ismail; Schlotterbeck, Götz; Winkler, MartinSelected mono- and bicationic quats were compounded with polyethylene. The physicochemical surface properties, leaching behavior, and antibacterial activity of such modified samples were investigated. Contact angle measurements and fluorescein binding assays showed the presence of quaternary ammonium groups at the surface. After storing the samples in 50°C warm water for 30 days, several were still antimicrobially active. No correlation between the number of exposed N+ head groups after leaching and the antibacterial activity was observed. There is however a qualitative correlation of the antibacterial activity with the contact angles and surface concentrations of N+ before leaching/storing in warm water.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation An Acute Ocfentanil Fatality: A Case Report with Postmortem Concentrations(Oxford University Press, 2016) Dussy, Franz; Hangartner, Sarah; Hamberg, Cornelia; Berchtold, Christoph; Scherer, Ulrich; Schlotterbeck, Götz; Wyler, David; Briellmann, ThomasA 24-year-old man known to consume illegal drugs was found dead in his apartment. A reclosable plastic zipper bag containing several hundred milligrams of a brown powder was found close to the dead body and the first assumption of the investigators was death due to heroin intoxication. Therefore, a legal autopsy was ordered. The following toxicological analysis revealed ocfentanil in urine and in the brown powder. Four different approaches for the determination of the ocfentanil concentrations in peripheral whole blood are described. Enrichment of ocfentanil from the powder was realized. With this reference, it was possible to determine the ocfentanil concentration in the seized powder to be 0.91%. Concentrations of ocfentanil were also determined in the sampled body fluids using the standard addition procedure. In peripheral blood 9.1 µg/L, in heart blood 27.9 µg/L and in urine 480 µg/L were measured. In addition, the antidepressant citalopram, the neuroleptic quetiapine and cannabinoids were found in urine and subsequently quantified in peripheral blood.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Epigenetic activation of MGAT3 and corresponding bisecting GlcNAc shortens the survival of cancer patients(Impact Journals LLC, 12.07.2016) Kohler, Reto; Anugraham, Merrina; Nunez Lopez, Monica; Xiao, Christina; Schoetzau, Andreas; Hettich, Timm; Schlotterbeck, Götz; Fedier, André; Jacob, Francis; Heinzelmann-Schwarz, ViolaBisecting GlcNAc on N-glycoproteins is described in E-cadherin-, EGF-, Wnt- and integrin- cancer-associated signaling pathways. However, the mechanisms regulating bisecting GlcNAc expression are not clear. Bisecting GlcNAc is attached to N-glycans through beta 1-4 N-acetylglucosaminyl transferase III (MGAT3), which is encoded by two exons flanked by high-density CpG islands. Despite a recently described correlation of MGAT3 and bisecting GlcNAc in ovarian cancer cells, it remains unknown whether DNA methylation is causative for the presence of bisecting GlcNAc. Here, we narrow down the regulatory genomic region and show that reconstitution of MGAT3 expression with 5-Aza coincides with reduced DNA methylation at the MGAT3 transcription start site. The presence of bisecting GlcNAc on released N-glycans was detected by mass spectrometry (LC-ESI-qTOF-MS/MS) in serous ovarian cancer cells upon DNA methyltransferase inhibition. The regulatory impact of DNA methylation on MGAT3 was further evaluated in 18 TCGA cancer types (n = 6118 samples) and the results indicate an improved overall survival in patients with reduced MGAT3 expression, thereby identifying long-term survivors of high-grade serous ovarian cancers (HGSOC). Epigenetic activation of MGAT3 was also confirmed in basal-like breast cancers sharing similar molecular and genetic features with HGSOC. These results provide novel insights into the epigenetic regulation of MGAT3/bisecting01A - Beitrag in wissenschaftlicher Zeitschrift
