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"Organische Chemie"
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The detection of EpCAM+ and EpCAM– circulating tumor cells
by
Lenferink, Aufried T. M.
,
Wit, Sanne de
,
Tibbe, Arjan G. J.
in
14/1
,
14/34
,
631/1647/245/2225
2015
EpCAM expressing circulating tumor cells, detected by CellSearch, are predictive of short survival in several cancers and may serve as a liquid biopsy to guide therapy. Here we investigate the presence of EpCAM
+
CTC detected by CellSearch and EpCAM
–
CTC discarded by CellSearch, after EpCAM based enrichment. EpCAM
–
CTC were identified by filtration and fluorescent labelling. This approach was validated using different cell lines spiked into blood and evaluated on blood samples of 27 metastatic lung cancer patients. The majority of spiked EpCAM
+
cells could be detected with CellSearch, whereas most spiked cells with EpCAM
low
or EpCAM
–
expression were detected using filtration. Five or more CTC were detected in 15% of the patient samples, this increased to 41% when adding the CTC detected in the discarded blood. The number of patients with CTC and the number of CTC detected were doubled by the presence of EpCAM
–
CTC. In this pilot study, the presence of EpCAM
+
CTC was associated with poor outcome, whereas the EpCAM
–
CTC were not. This observation will need to be confirmed in larger studies and molecular characterization needs to be conducted to elucidate differences between EpCAM
–
and EpCAM
+
CTC.
Journal Article
Mycotoxin profiling of 1000 beer samples with a special focus on craft beer
2017
Currently beer is booming, mainly due to the steady rise of craft breweries worldwide. Previous surveys for occurrence of mycotoxins in beer, were mainly focussed on industrial produced beer. The present survey reports the presence of mycotoxins in craft beer and how this compares to industrial produced beer. More than 1000 beers were collected from 47 countries, of which 60% were craft beers. A selection of 1000 samples were screened for the presence of aflatoxin B1, ochratoxin A (OTA), zearalenone (ZEN), fumonisins (FBs), T-2 and HT-2 toxins (T-2 and HT-2) and deoxynivalenol (DON) using a mycotoxin 6-plex immunoassay. For confirmatory analysis, a liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and applied. The 6-plex screening showed discrepancies with the LC-MS/MS analysis, possibly due to matrix interference and/or the presence of unknown mycotoxin metabolites. The major mycotoxins detected were DON and its plant metabolite deoxynivalenol-3-β-D-glucopyranoside (D3G). The 6-plex immunoassay reported the sum of DON and D3G (DON+D3G) contaminations ranging from 10 to 475 μg/L in 406 beers, of which 73% were craft beers. The popular craft beer style imperial stout, had the highest percentage of samples suspected positive (83%) with 29% of all imperial stout beers having DON+D3G contaminations above 100 μg/L. LC-MS/MS analysis showed that industrial pale lagers from Italy and Spain, predominantly contained FBs (3-69 μg/L). Besides FBs, African traditional beers also contained aflatoxins (0.1-1.2 μg/L). The presence of OTA, T-2, HT-2, ZEN, β-zearalenol, 3/15-acetyl-DON, nivalenol and the conjugated mycotoxin zearalenone 14-sulfate were confirmed in some beers. This study shows that in 27 craft beers, DON+D3G concentrations occurred above (or at) the Tolerable Daily Intake (TDI). Exceeding the TDI, may have a health impact. A better control of brewing malts for craft beer, should be put in place to circumvent this potential problem.
Journal Article
Proteomics as a new tool to study fingermark ageing in forensics
2018
Fingermarks are trace evidence of great forensic importance, and their omnipresence makes them pivotal in crime investigation. Police and law enforcement authorities have exploited fingermarks primarily for personal identification, but crucial knowledge on when fingermarks were deposited is often lacking, thereby hindering crime reconstruction. Biomolecular constituents of fingermark residue, such as amino acids, lipids and proteins, may provide excellent means for fingermark age determination, however robust methodologies or detailed knowledge on molecular mechanisms in time are currently not available. Here, we address fingermark age assessment by: (i) drafting a first protein map of fingermark residue, (ii) differential studies of fresh and aged fingermarks and (iii), to mimic real-world scenarios, estimating the effects of donor contact with bodily fluids on the identification of potential age biomarkers. Using a high-resolution mass spectrometry-based proteomics approach, we drafted a characteristic fingermark proteome, of which five proteins were identified as promising candidates for fingermark age estimation. This study additionally demonstrates successful identification of both endogenous and contaminant proteins from donors that have been in contact with various bodily fluids. In summary, we introduce state-of-the-art proteomics as a sensitive tool to monitor fingermark aging on the protein level with sufficient selectivity to differentiate potential age markers from body fluid contaminants.
Journal Article
Identification of Chaoborus kairomone chemicals that induce defences in Daphnia
by
Schmitz, Oliver J
,
Leo, Markus
,
Albada, Bauke
in
Aquatic ecosystems
,
Bioassays
,
Biological activity
2018
Infochemicals play important roles in aquatic ecosystems. They even modify food web interactions, such as by inducing defenses in prey. In one classic but still not fully understood example, the planktonic freshwater crustacean Daphnia pulex forms specific morphological defenses (neckteeth) induced by chemical cues (kairomones) released from its predator, the phantom midge larva Chaoborus. On the basis of liquid chromatography, mass spectrometry, and chemical synthesis, we report here the chemical identity of the Chaoborus kairomone. The biologically active cues consist of fatty acids conjugated to the amino group of glutamine via the N terminus. These cues are involved in Chaoborus digestive processes, which explains why they are consistently released despite the disadvantage for its emitter. The identification of the kairomone may allow in-depth studies on multiple aspects of this inducible defense system.
Journal Article
Kauniolide synthase is a P450 with unusual hydroxylation and cyclization-elimination activity
2018
Guaianolides are an important class of sesquiterpene lactones with unique biological and pharmaceutical properties. They have been postulated to be derived from germacranolides, but for years no progress has been made in the elucidation of their biosynthesis that requires an unknown cyclization mechanism. Here we demonstrate the isolation and characterization of a cytochrome P450 from feverfew (
Tanacetum parthenium
), kauniolide synthase. Kauniolide synthase catalyses the formation of the guaianolide kauniolide from the germacranolide substrate costunolide. Unlike most cytochrome P450s, kauniolide synthase combines stereoselective hydroxylation of costunolide at the C3 position, with water elimination, cyclization and regioselective deprotonation. This unique mechanism of action is supported by in silico modelling and docking experiments. The full kauniolide biosynthesis pathway is reconstructed in the heterologous hosts
Nicotiana benthamiana
and yeast, paving the way for biotechnological production of guaianolide-type sesquiterpene lactones.
Guaianolides are pharmaceutically interesting molecules. Here, the authors isolate the enzyme kauniolide synthase from feverfew, show that it converts constunolide into a guaianolide via an unusual mechanism of action, and reconstruct the full kauniolide biosynthesis pathway in host organisms.
Journal Article
Calling Biomarkers in Milk Using a Protein Microarray on Your Smartphone
by
Ozcan, Aydogan
,
Tokarski, Christian
,
Nielen, Michel W. F.
in
Analytical chemistry
,
Animals
,
Antibodies
2015
Here we present the concept of a protein microarray-based fluorescence immunoassay for multiple biomarker detection in milk extracts by an ordinary smartphone. A multiplex immunoassay was designed on a microarray chip, having built-in positive and negative quality controls. After the immunoassay procedure, the 48 microspots were labelled with Quantum Dots (QD) depending on the protein biomarker levels in the sample. QD-fluorescence was subsequently detected by the smartphone camera under UV light excitation from LEDs embedded in a simple 3D-printed opto-mechanical smartphone attachment. The somewhat aberrant images obtained under such conditions, were corrected by newly developed Android-based software on the same smartphone, and protein biomarker profiles were calculated. The indirect detection of recombinant bovine somatotropin (rbST) in milk extracts based on altered biomarker profile of anti-rbST antibodies was selected as a real-life challenge. RbST-treated and untreated cows clearly showed reproducible treatment-dependent biomarker profiles in milk, in excellent agreement with results from a flow cytometer reference method. In a pilot experiment, anti-rbST antibody detection was multiplexed with the detection of another rbST-dependent biomarker, insulin-like growth factor 1 (IGF-1). Milk extract IGF-1 levels were found to be increased after rbST treatment and correlated with the results obtained from the reference method. These data clearly demonstrate the potential of the portable protein microarray concept towards simultaneous detection of multiple biomarkers. We envisage broad application of this 'protein microarray on a smartphone'-concept for on-site testing, e.g., in food safety, environment and health monitoring.
Journal Article
Dynamic stereochemistry of chiral compounds
2007,2008
In this book, the reader is presented with a comprehensive overview of fundamental concepts of asymmetric synthesis along with in-depth discussion of strategies for the synthesis and stereoselective interconversion of compounds exhibiting central axial and planar chirality, numerous racemization, and diastereomerization reactions. Details of analytical methods are provided and discussed as well as topics relating to the design of fascinating topologically chiral assemblies and molecular technomimetic devices in the context of dynamic stereochemistry. Strategies and recent developments that address important synthetic challenges are presented and highlighted with hundreds of examples, applications and detailed mechanisms.
TiO2 Photocatalyzed Oxidation of Drugs Studied by Laser Ablation Electrospray Ionization Mass Spectrometry
by
Ritala, Mikko
,
van Geenen, Fred A. M. G.
,
Kostiainen, Risto
in
Analytical Chemistry
,
Bioinformatics
,
Biotechnology
2019
In drug discovery, it is important to identify phase I metabolic modifications as early as possible to screen for inactivation of drugs and/or activation of prodrugs. As the major class of reactions in phase I metabolism is oxidation reactions, oxidation of drugs with TiO
2
photocatalysis can be used as a simple non-biological method to initially eliminate (pro)drug candidates with an undesired phase I oxidation metabolism. Analysis of reaction products is commonly achieved with mass spectrometry coupled to chromatography. However, sample throughput can be substantially increased by eliminating pretreatment steps and exploiting the potential of ambient ionization mass spectrometry (MS). Furthermore, online monitoring of reactions in a time-resolved way would identify sequential modification steps. Here, we introduce a novel (time-resolved) TiO
2
-photocatalysis laser ablation electrospray ionization (LAESI) MS method for the analysis of drug candidates. This method was proven to be compatible with both TiO
2
-coated glass slides as well as solutions containing suspended TiO
2
nanoparticles, and the results were in excellent agreement with studies on biological oxidation of verapamil, buspirone, testosterone, andarine, and ostarine. Finally, a time-resolved LAESI MS setup was developed and initial results for verapamil showed excellent analytical stability for online photocatalyzed oxidation reactions within the set-up up to at least 1 h.
Graphical Abstract
Journal Article
Radiation processing of polymer materials and its industrial applications
by
Makuuchi, Keizo
,
Cheng, Song
in
Chemical & Biochemical
,
Effect of radiation on
,
Industrial applications
2011
Up-to-date, comprehensive coverage on radiation-processed polymer materials and their applications Offering a unique perspective of the industrial and commercial applications of the radiation processing of polymers, this insightful reference examines the fundamental scientific principles and cutting-edge developments advancing this diverse field. Through a variety of case studies, detailed examples, and economic feasibility analysis, Radiation Processing of Polymer Materials and Its Industrial Applications systematically explains the commercially viable ways to process and use radiation-processed polymeric materials in industrial products. In addition, this one-of-kind text: Covers important chemistry and processing fundamentals, while emphasizing their translation into practical applications of radiation-processed polymers Incorporates new applications in nanotechnology, biomaterials, and recycling Systematically discusses new developments in the field and summarizes past achievements By helping readers—from students to scientists, engineers, technicians, and sales and marketing professionals—understand and solve problems associated with radiation processing of polymers, Radiation Processing of Polymer Materials and Its Industrial Applications serves as an essential reference and fills an important gap in the literature.