Entwicklung und Anwendung von Analysenverfahren zur Erfassung cyanobakterieller Toxine Basierend auf flüssigkeitschromatographischer Trennung und massenspektrometrischer Detektion

Die eindeutige Identifizierung und quantitative Bestimmung cyanobakterieller Toxine im Trink-, Brauch- und Badewasser sowie aus dem darin enthaltenen Phytoplankton ist hinsichtlich der Einhaltung von Grenz- und Richtwerten zum Schutz der Gesundheit des Menschen von großer Bedeutung. Die vorliegende Dissertation beschäftigt sich mit der Analytik der cyanobakteriellen Toxine unter Einsatz einer LC-MS/MS-Kopplung. Im Rahmen dieser Arbeit wurde festgestellt, dass die internationale Norm ISO 20179, zur Kontrolle der Einhaltung des WHO-Richtwertes hinsichtlich der Kontamination von Trinkwasser mit Microcystinen nur unzureichend geeignet ist. Für die Entwicklung und den routinemäßigen Einsatz einer Multikomponenten-Analysen-Methode zur simultanen Erfassung cyanobakterieller Toxine wurde eine effektive gemeinsame Extraktion der Toxine während der Probenaufarbeitung untersucht. Um die Vielzahl der cyanobakteriellen Toxine unterschiedlicher Struktur in nur einem analytischen Lauf qualitativ zu erfassen, wurde eine LC-MS/MS-Methode mit vorwiegender Detektion im Precursor-Ionen-Scan-Modus entwickelt. Die chromatographische Voraussetzung für die Anwendung dieses MS-Modus bestand in einer Gruppentrennung der cyanobakteriellen Toxine, die eine selektive Detektion mit entsprechendem Tochterfragment erlaubt. Die entwickelte Precursor-Ionen-Scan-Methode ermöglicht die Erfassung einer Reihe ungewöhnlicher, d. h. seltener Strukturvarianten cyanobakterieller Toxine neben häufig vorkommenden, wodurch die schnelle Einschätzung des toxischen Potenzials von Phytoplanktonproben unbekannter Spezieszusammensetzung gelingt

Application of a screening method for cyanobacterial toxins in natural samples

Cyanobacterial toxins as microcystins (MCs), nodularins (NODs), Paralytic Shellfish Poisoning (PSP) toxins, anatoxins (ANAs), and cylindrospermopsins (CYNs) with over 100 known varieties, occur worldwide associated with human and animal lethal poisoning.In contrast to all analytical methods for toxin determination are based on LC/MS-MS measurements with Multiple Reaction Monitoring (MRM) the application of Precursor Ion mode allows the coverage of all these structural variants. Although in MRM mode enables a higher sensitivity, a lot of information regarding structural changes is missed. The new generation of Q-TRAPs combines the advantages of quadrupoles having a high selectivity with the high sensitivity of ion-trap systems. Here we published results, showing the suitability of Precursor Ion mode for detection of cyanobacterial toxins extracted from phytoplankton

Health anxiety - An indicator of higher interoceptive sensitivity?

Background and objectives: According to cognitive-behavioral models, health anxiety arises from the misattribution of normal bodily sensations as signs of a severe illness. Consequently, higher levels of interoceptive accuracy might be critically involved in the development of health anxiety. Methods: To test this central assumption of cognitive behavioral models of health anxiety, we assessed interoceptive accuracy in a sample of college students (N = 100). Two interoceptive tasks (detection of one's own heartbeat using the Schandry paradigm and detection of nonspecific skin conductance fluctuations, NSCFs) were used. Results: We found no indication for a positive association between facets of health anxiety and a higher interoceptive accuracy in the two tasks. In fact, worse heartbeat perception was associated with higher health anxiety as measured by two questionnaires whereas perception of NSCFs was not significantly related to any facet of health anxiety. In addition, we found a bias to overestimate NSCFs in people with heightened health anxiety. Limitations: Because a sample of college students served as participants, the generalization of the findings is limited and further studies in patients with the diagnosis of hypochondriasis are necessary. Conclusions: The findings of both interoceptive paradigms suggest that health anxiety is not associated with better but rather with less accurate and biased interoceptive sensitivity. Probably, not a heightened interoceptive sensitivity but rather the bias in overestimating harmless somatic cues is more relevant for the maintenance of health anxiety. Our results are in line with recent research in other somatoform disorders. (C) 2014 Elsevier Ltd. All rights reserved

Nanomechanical Characterization of Vertical Nanopillars Using an MEMS-SPM Nano-Bending Testing Platform

Nanomechanical characterization of vertically aligned micro- and nanopillars plays an important role in quality control of pillar-based sensors and devices. A microelectromechanical system based scanning probe microscope (MEMS-SPM) has been developed for quantitative measurement of the bending stiffness of micro- and nanopillars with high aspect ratios. The MEMS-SPM exhibits large in-plane displacement with subnanometric resolution and medium probing force beyond 100 micro-Newtons. A proof-of-principle experimental setup using an MEMS-SPM prototype has been built to experimentally determine the in-plane bending stiffness of silicon nanopillars with an aspect ratio higher than 10. Comparison between the experimental results and the analytical and FEM evaluation has been demonstrated. Measurement uncertainty analysis indicates that this nano-bending system is able to determine the pillar bending stiffness with an uncertainty better than 5%, provided that the pillars’ stiffness is close to the suspending stiffness of the MEMS-SPM. The MEMS-SPM measurement setup is capable of on-chip quantitative nanomechanical characterization of pillar-like nano-objects fabricated out of different materials

Detection of harmful cyanobacteria and their toxins by both PCR amplification and LC-MS during a bloom event. Toxicon

Abstract We briefly report here the occurrence of toxic blooms in the eutrophic reservoir Billings, Sa˜o Paulo city, Brazil. Water samples were collected in May 2004, during a cyanobacterial bloom. The presence of toxic species was confirmed by using PCR amplifications of a fragment region of genes encoding microcystin synthetase-mcyB. The determination of toxins was performed by liquid chromatography coupled with mass spectrometry (LC-MS). LC-MS analyses of the toxins from the bloom revealed variants of microcystins (MC), such as MC-LR, MC-RR and MC-YR. HPLC-FLD was used to determine the paralytic shellfish poisoning (PSP) saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 (GTX2) and 3 (GTX3). GTX2, GTX3 and NEO were detected for the first time in a natural sample from Billings reservoir. These results are a contribution to the knowledge of the biogeography of toxic cyanobacteria and their toxins, specifically in Sa˜o Paulo.