Swiss Center for Applied Human Toxicology

Genève, Switzerland

Swiss Center for Applied Human Toxicology

Genève, Switzerland
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Dozio V.,University of Geneva | Dozio V.,Swiss Center for Applied Human Toxicology | Sanchez J.-C.,University of Geneva | Sanchez J.-C.,Swiss Center for Applied Human Toxicology
Journal of Extracellular Vesicles | Year: 2017

Little is known about the composition and functional differences between extracellular vesicle (EV) subsets, such as microvesicles (MVs) and exosomes (EXOs), nor to what extent their cargo reflects the phenotypic state of the cell of origin. Brain endothelial cells are the constitutive part of the blood-brain barrier (BBB), a selective barrier that maintains brain homeostasis. BBB impairment is associated with several neuroinflammatory diseases with the pro-inflammatory cytokine tumour necrosis factor (TNF) often playing a key role. In the present study, shotgun proteomics and parallel reaction monitoring (PRM)-based targeted mass spectrometry were used to characterise brain endothelial cell-released EVs, and to study how TNF exposure modulated EV protein cargoes. MVs were found to be enriched in mitochondrial and cytoskeletal proteins, whereas EXOs were enriched in adhesion, histone and ribosomal proteins. After stimulation with TNF, several proteins involved in TNF and NF-kB signalling pathways, that were found to be differentially expressed in cells, were also differentially expressed in both MVs and EXOs. Thus, our results revealed some novel proteins as potentially useful candidates for discriminating between MVs and EXOs, together with additional evidence that cells "package" proteins in EVs systematically and according to their phenotypic state. © 2017 The Author(s).

Jeanneret F.,University of Geneva | Tonoli D.,University of Geneva | Rossier M.F.,Swiss Center for Applied Human Toxicology | Boccard J.,University of Geneva | Rudaz S.,University of Geneva
Journal of chromatography. A | Year: 2016

This review presents the evolution of steroid analytical techniques, including gas chromatography coupled to mass spectrometry (GC-MS), immunoassay (IA) and targeted liquid chromatography coupled to mass spectrometry (LC-MS), and it evaluates the potential of extended steroid profiles by a metabolomics-based approach, namely steroidomics. Steroids regulate essential biological functions including growth and reproduction, and perturbations of the steroid homeostasis can generate serious physiological issues; therefore, specific and sensitive methods have been developed to measure steroid concentrations. GC-MS measuring several steroids simultaneously was considered the first historical standard method for analysis. Steroids were then quantified by immunoassay, allowing a higher throughput; however, major drawbacks included the measurement of a single compound instead of a panel and cross-reactivity reactions. Targeted LC-MS methods with selected reaction monitoring (SRM) were then introduced for quantifying a small steroid subset without the problems of cross-reactivity. The next step was the integration of metabolomic approaches in the context of steroid analyses. As metabolomics tends to identify and quantify all the metabolites (i.e., the metabolome) in a specific system, appropriate strategies were proposed for discovering new biomarkers. Steroidomics, defined as the untargeted analysis of the steroid content in a sample, was implemented in several fields, including doping analysis, clinical studies, in vivo or in vitro toxicology assays, and more. This review discusses the current analytical methods for assessing steroid changes and compares them to steroidomics. Steroids, their pathways, their implications in diseases and the biological matrices in which they are analysed will first be described. Then, the different analytical strategies will be presented with a focus on their ability to obtain relevant information on the steroid pattern. The future technical requirements for improving steroid analysis will also be presented. Copyright © 2015 Elsevier B.V. All rights reserved.

Chapman K.,National Center for the Replacement | Creton S.,National Center for the Replacement | Kupferschmidt H.,Swiss Toxicological Information Center | Bond G.R.,Cincinnati Drug and Poison Information Center | And 2 more authors.
Regulatory Toxicology and Pharmacology | Year: 2010

Acute toxicity studies are no longer required to support first clinical trials of pharmaceuticals in man. However, it is unclear in the wording of the revised ICH M3 whether acute toxicity studies are required later in drug development (e.g., phase 3) in order to support the management of overdose. The NC3Rs held a workshop in January 2010 with representatives from international poison centres, the pharmaceutical and chemical industries, and regulatory and government bodies to explore further whether acute toxicity studies are used to support the clinical management of overdose of pharmaceuticals and whether this work can be translated to other sectors such as the chemical industry. The consensus formed at the workshop was that acute toxicity studies are not used for managing overdose of pharmaceuticals and are of little value in treating human poisoning from chemicals. In this paper, the authors describe the key considerations in treating human overdose and poisoning, challenge the value of the classification and labelling process of chemicals for this purpose and discuss how acute toxicity studies can be improved to better inform risk assessment.1. © 2010 Elsevier Inc. All rights reserved.

Badoud F.,University of Geneva | Badoud F.,Swiss Center for Applied Human Toxicology | Grata E.,University of Geneva | Grata E.,Swiss Center for Applied Human Toxicology | And 10 more authors.
Analytical and Bioanalytical Chemistry | Year: 2011

The urinary steroid profile is constituted by anabolic androgenic steroids, including testosterone and its relatives, that are extensively metabolized into phase II sulfated or glucuronidated steroids. The use of liquid chromatography coupled to mass spectrometry (LC-MS) is an issue for the direct analysis of conjugated steroids, which can be used as urinary markers of exogenous steroid administration in doping analysis, without hydrolysis of the conjugated moiety. In this study, a sensitive and selective ultra high-pressure liquid chromatography coupled to quadrupole time-of-flight mass spectrometer (UHPLC-QTOF-MS) method was developed to quantify major urinary metabolites simultaneously after testosterone intake. The sample preparation of the urine (1 mL) was performed by solid-phase extraction on Oasis HLB sorbent using a 96-well plate format. The conjugated steroids were analyzed by UHPLC-QTOF-MSE with a single-gradient elution of 36 min (including re-equilibration time) in the negative electrospray ionization mode. MS E analysis involved parallel alternating acquisitions of both low- and high-collision energy functions. The method was validated and applied to samples collected from a clinical study performed with a group of healthy human volunteers who had taken testosterone, which were compared with samples from a placebo group. Quantitative results were also compared to GC-MS and LC-MS/MS measurements, and the correlations between data were found appropriate. The acquisition of full mass spectra over the entire mass range with QTOF mass analyzers gives promise of the opportunity to extend the steroid profile to a higher number of conjugated steroids. © 2011 Springer-Verlag.

Nussbaumer S.,University of Geneva | Nussbaumer S.,Swiss Center for Applied Human Toxicology | Geiser L.,Swiss Center for Applied Human Toxicology | Sadeghipour F.,University of Geneva | And 6 more authors.
Analytical and Bioanalytical Chemistry | Year: 2012

A simple wipe sampling procedure was developed for the surface contamination determination of ten cytotoxic drugs: cytarabine, gemcitabine, methotrexate, etoposide phosphate, cyclophosphamide, ifosfamide, irinotecan, doxorubicin, epirubicin and vincristine. Wiping was performed using Whatman filter paper on different surfaces such as stainless steel, polypropylene, polystyrol, glass, latex gloves, computer mouse and coated paperboard. Wiping and desorption procedures were investigated: The same solution containing 20% acetonitrile and 0.1% formic acid in water gave the best results. After ultrasonic desorption and then centrifugation, samples were analysed by a validated liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in selected reaction monitoring mode. The whole analytical strategy from wipe sampling to LC-MS/MS analysis was evaluated to determine quantitative performance. The lowest limit of quantification of 10 ng per wiping sample (i.e. 0.1 ng cm-2) was determined for the ten investigated cytotoxic drugs. Relative standard deviation for intermediate precision was always inferior to 20%. As recovery was dependent on the tested surface for each drug, a correction factor was determined and applied for real samples. The method was then successfully applied at the cytotoxic production unit of the Geneva University Hospitals pharmacy. © 2011 Springer-Verlag.

Nussbaumer S.,University of Geneva | Nussbaumer S.,Swiss Center for Applied Human Toxicology | Fleury-Souverain S.,University of Geneva | Antinori P.,Swiss Center for Applied Human Toxicology | And 7 more authors.
Analytical and Bioanalytical Chemistry | Year: 2010

A liquid chromatography separation with electrospray ionisation and tandem mass spectrometry detection method was developed for the simultaneous quantification of ten commonly handled cytotoxic drugs in a hospital pharmacy. These cytotoxic drugs are cytarabine, gemcitabine, methotrexate, etoposide phosphate, cyclophosphamide, ifosfamide, irinotecan, doxorubicin, epirubicin and vincristine. The chromatographic separation was carried out by RPLC in less than 21 min, applying a gradient elution of water and acetonitrile in the presence of 0.1% formic acid. MS/MS was performed on a triple quadrupole in selected reaction monitoring mode. The analytical method was validated to determine the limit of quantification (LOQ) and quantitative performance: lowest LOQs were between 0.25 and 2 ng mL-1 for the ten investigated cytotoxic drugs; trueness values (i.e. recovery) were between 85% and 110%, and relative standard deviations for both repeatability and intermediate precision were always inferior to 15%. The multi-compound method was successfully applied for the quality control of pharmaceutical formulations and for analyses of spiked samples on potentially contaminated surfaces. [Figure not available: see fulltext.] © 2010 Springer-Verlag.

Pak H.,University of Geneva | Nikitin F.,Swiss Institute of Bioinformatics | Gluck F.,University of Geneva | Gluck F.,Swiss Center for Applied Human Toxicology | And 5 more authors.
Journal of the American Society for Mass Spectrometry | Year: 2013

Data-independent mass spectrometry activates all ion species isolated within a given mass-to-charge window (m/z) regardless of their abundance. This acquisition strategy overcomes the traditional data-dependent ion selection boosting data reproducibility and sensitivity. However, several tandem mass (MS/MS) spectra of the same precursor ion are acquired during chromatographic elution resulting in large data redundancy. Also, the significant number of chimeric spectra and the absence of accurate precursor ion masses hamper peptide identification. Here, we describe an algorithm to preprocess data-independent MS/MS spectra by filtering out noise peaks and clustering the spectra according to both the chromatographic elution profiles and the spectral similarity. In addition, we developed an approach to estimate the m/z value of precursor ions from clustered MS/MS spectra in order to improve database search performance. Data acquired using a small 3 m/z units precursor mass window and multiple injections to cover a m/z range of 400-1400 was processed with our algorithm. It showed an improvement in the number of both peptide and protein identifications by 8 % while reducing the number of submitted spectra by 18 % and the number of peaks by 55 %. We conclude that our clustering method is a valid approach for data analysis of these data-independent fragmentation spectra. The software including the source code is available for the scientific community. [Figure not available: see fulltext.] © 2013 American Society for Mass Spectrometry.

Kasraee B.,University of Geneva | Nikolic D.S.,University of Geneva | Salomon D.,University of Geneva | Carraux P.,University of Geneva | And 7 more authors.
Experimental Dermatology | Year: 2012

We assessed the ability of ebselen, a glutathione peroxidase mimic, to reduce pigmentation in various models. In murine B16 melanocytes, 25μm ebselen inhibited melanogenesis and induced a depolymerisation of actin filaments. In co-cultures of B16 melanocytes with BDVII keratinocytes, a pretreatment of melanocytes with ebselen resulted in a strong inhibition of melanosome transfer to keratinocytes, as shown under optical and electron microscopy. In reconstructed epidermis, topical 0.5% ebselen led to a twofold decrease of melanin without affecting the density of active melanocytes. A similar result was obtained with topical 0.5% ebselen in black guinea pig ears. Ebselen induced a decrease of epidermal melanin parallel to a localisation of melanin and melanosomes in the basal layer. Ebselen appears as a new depigmenting compound that inhibits melanin synthesis and melanosome transfer to keratinocytes. © 2011 John Wiley & Sons A/S.

Odermatt A.,Swiss Center for Applied Human Toxicology | Nashev L.G.,Swiss Center for Applied Human Toxicology
Journal of Steroid Biochemistry and Molecular Biology | Year: 2010

The primary function of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is to catalyze the conversion of inactive to active glucocorticoid hormones and to modulate local glucocorticoid-dependent gene expression. Thereby 11β-HSD1 plays a key role in the regulation of metabolic functions and in the adaptation of the organism to energy requiring situations. Importantly, elevated 11β-HSD1 activity has been associated with metabolic disorders, and recent investigations with rodent models of obesity and type 2 diabetes provided evidence for beneficial effects of 11β-HSD1 inhibitors, making this enzyme a promising therapeutic target. Several earlier and recent studies, mainly performed in vitro, revealed a relatively broad substrate spectrum of 11β-HSD1 and suggested that this enzyme has additional functions in the metabolism of some neurosteroids (7-oxy- and 11-oxyandrogens and -progestins) and 7-oxysterols, as well as in the detoxification of various xenobiotics that contain reactive carbonyl groups. While there are many studies on the effect of inhibitors on cortisone reduction and circulating glucocorticoid levels and on the transcriptional regulation of 11β-HSD1 in obesity and diabetes, only few address the so-called alternative functions of this enzyme. We review recent progress on the biochemical characterization of 11β-HSD1, with a focus on cofactor and substrate specificity and on possible alternative functions of this enzyme. © 2010 Elsevier Ltd. All rights reserved.

Felser A.,University of Basel | Stoller A.,University of Basel | Morand R.,University of Basel | Schnell D.,University of Basel | And 7 more authors.
Toxicology | Year: 2014

Dronedarone is an amiodarone-like antiarrhythmic drug associated with severe liver injury. Since dronedarone inhibits mitochondrial respiration and β-oxidation in vitro, mitochondrial toxicity may also explain dronedarone-associated hepatotoxicity in vivo. We therefore studied hepatotoxicity of dronedarone (200mg/kg/day for 2 weeks or 400mg/kg/day for 1 week by intragastric gavage) in heterozygous juvenile visceral steatosis (jvs+/-) and wild-type mice. Jvs+/- mice have reduced carnitine stores and are sensitive for mitochondrial β-oxidation inhibitors. Treatment with dronedarone 200mg/kg/day had no effect on body weight, serum transaminases and bilirubin, and hepatic mitochondrial function in both wild-type and jvs+/- mice. In contrast, dronedarone 400mg/kg/day was associated with a 10-15% drop in body weight, and a 3-5-fold increase in transaminases and bilirubin in wild-type mice and, more accentuated, in jvs+/- mice. In vivo metabolism of intraperitoneal 14C-palmitate was impaired in wild-type, and, more accentuated, in jvs+/- mice treated with 400mg/kg/day dronedarone compared to vehicle-treated mice. Impaired β-oxidation was also found in isolated mitochondria ex vivo. A likely explanation for these findings was a reduced activity of carnitine palmitoyltransferase 1a in liver mitochondria from dronedarone-treated mice. In contrast, dronedarone did not affect the activity of the respiratory chain ex vivo.We conclude that dronedarone inhibits mitochondrial β-oxidation in and ex vivo, but not the respiratory chain. Jvs+/- mice are slightly more sensitive for the effect of dronedarone on mitochondrial β-oxidation than wild-type mice. The results suggest that inhibition of mitochondrial β-oxidation is an important mechanism of hepatotoxicity associated with dronedarone. © 2014 Elsevier Ireland Ltd.

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