The implementation of liquid chromatography tandem mass spectrometry for the official control of lipophilic toxins in seafood: Single-laboratory validation under four chromatographic conditions

We performed a comprehensive study to assess the fit for purpose of four chromatographic conditions for the determination of six groups of marine lipophilic toxins (okadaic acid and dinophysistoxins, pectenotoxins, azaspiracids, yessotoxins, gymnodimine and spirolides) by LC-MS/MS to select the most suitable conditions as stated by the European Union Reference Laboratory for Marine Biotoxins (EURLMB). For every case, the elution gradient has been optimized to achieve a total run-time cycle of 12 min. We performed a single-laboratory validation for the analysis of three relevant matrices for the seafood aquaculture industry (mussels, pacific oysters and clams), and for sea urchins for which no data about lipophilic toxins have been reported before. Moreover, we have compared the method performance under alkaline conditions using two quantification strategies: the external standard calibration (EXS) and the matrix-matched standard calibration (MMS). Alkaline conditions were the only scenario that allowed detection windows with polarity switching in a 3200 QTrap mass spectrometer, thus the analysis of all toxins can be accomplished in a single run, increasing sample throughput. The limits of quantification under alkaline conditions met the validation requirements established by the EURLMB for all toxins and matrices, while the remaining conditions failed in some cases. The accuracy of the method and the matrix effects where generally dependent on the mobile phases and the seafood species. The MMS had a moderate positive impact on method accuracy for crude extracts, but it showed poor trueness for seafood species other than mussels when analyzing hydrolyzed extracts. Alkaline conditions with EXS and recovery correction for OA were selected as the most proper conditions in the context of our laboratory. This comparative study can help other laboratories to choose the best conditions for the implementation of LC-MS/MS according to their own necessities.

Control of pancreatic β-cell mass and function by gluco-incretin hormones : identification of novel regulatory mechanisms for the treatment of diabetes

Summary : Control of pancreatic ß-cell mass and function by gluco-incretin hormones: Identification of novel regulatory mechanisms for the treatment of diabetes The ß-cells of islets of Langerhans secrete insulin to reduce hyperglycemia. The number of pancreatic islet ß-cells and their capacity to secrete insulin is modulated in normal physiological conditions to respond to the metabolic demand of the organism. A failure of the endocrine pancreas to maintain an adequate insulin secretory capacity due to a reduced ß-cell number and function underlies the pathogenesis of both type 1 and type 2 diabetes. The molecular mechanisms controlling the glucose competence of mature ß-cells, i.e., the magnitude of their insulin secretion response to glucose, ß-cell replication, their differentiation from precursor cells and protection against apoptosis are poorly understood. To investigate these mechanisms, we studied the effects on ß-cells of the gluco-incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) which are secreted by intestinal endocrine cells after food intake. Besides acutely potentiating glucose-stimulated insulin secretion, these hormones induce ß-cell differentiation from precursor cells, stimulate mature ß-cell replication, and protect them against apoptosis. Therefore, understanding the molecular basis for gluco-incretin action may lead to the uncovering of novel ß-cell regulatory events with potential application for the treatment or prevention of diabetes. Islets from mice with inactivation of both GIP and GLP-1 receptor genes (dK0) present a defect in glucose-induced insulin secretion and are more sensitive than control islets to cytokine-induced apoptosis. To search for regulatory genes, that may control both glucose competence and protection against apoptosis, we performed comparative transcriptomic analysis of islets from control and dK0 mice. We found a strong down-regulation of the IGF1 Rexpression in dK0 islets. We demonstrated in both a mouse insulin-secreting cell line and primary islets, that GLP-1 stimulated IGF-1R expression and signaling. Importantly, GLP-1induced IGF-1R-dependent Akt phosphorylation required active secretion, indicating the presence of an autocrine activation mechanism. We further showed that activation of IGF-1R signaling was dependent on the secretion of IGF-2 and IGF-2 expression was regulated by nutrients. Finally, we demonstrated that the IGF-Z/IGF-1R autocrine loop was required for GLP-1 i) to protect ß-cells against cytokine-induced apoptosis, ii) to enhance their glucose competence and iii) to increase ß-cell proliferation. Résumé : Contrôle de la masse des cellules ß pancréatiques et de leur fonction par les hormones glucoincrétines: Identification de nouveaux mécanismes régulateurs pour le traitement du diabète Les cellules ß des îlots de Langerhans sécrètent l'insuline pour diminuer l'hyperglycémie. Le nombre de cellules ß et leur capacité à sécréter l'insuline sont modulés dans les conditions physiologiques normales pour répondre à la demande métabolique de l'organisme. Un échec du pancréas endocrine à maintenir sa capacité sécrétoire d'insuline dû à une diminution du nombre et de la fonction des cellules ß conduit au diabète de type 1 et de type 2. Les mécanismes moléculaires contrôlant la compétence au glucose des cellules ß matures, tels que, l'augmentation de la sécrétion d'insuline en réponse au glucose, la réplication des cellules ß, leur différentiation à partir de cellules précurseurs et la protection contre l'apoptose sont encore peu connus. Afin d'examiner ces mécanismes, nous avons étudié les effets sur les cellules ß des hormones gluco-incrétines, glucose-dépendent insulinotropic polypeptide (G1P) et glucagon-like peptide-1 (GLP-1) qui sont sécrétées par les cellules endocrines de l'intestin après la prise alimentaire. En plus de potentialiser la sécrétion d'insuline induite par le glucose, ces hormones induisent la différentiation de cellules ß à partir de cellules précurseurs, stimulent leur prolifération et les protègent contre l'apoptose. Par conséquent, comprendre les mécanismes d'action des gluco-incrétines permettrait de découvrir de nouveaux processus régulant les cellules ß avec d'éventuelles applications dans le traitement ou la prévention du diabète. Les îlots de souris ayant une double inactivation des gènes pour les récepteurs du GIP et du GLP-1 (dK0) présentent un défaut de sécrétion d'insuline stimulée par le glucose et une sensibilité accrue à l'apoptose induite par les cytokines. Afin de déterminer les gènes régulés, qui pourraient contrôler à la fois la compétence au glucose et la protection contre l'apoptose, nous avons effectué une analyse comparative transcriptomique sur des îlots de souris contrôles et dKO. Nous avons constaté une forte diminution de l'expression d'IGF-1R dans les îlots dKO. Nous avons démontré, à la fois dans une lignée cellulaire murine sécrétant l'insuline et dans îlots primaires, que le GLP-1 stimulait l'expression d'IGF-1R et sa voie de signalisation. Par ailleurs, la phosphorylation d'Akt dépendante d'IGF1-R induite parle GLP-1 nécessite une sécrétion active, indiquant la présence d'un mécanisme d'activation autocrine. Nous avons ensuite montré que l'activation de la voie de signalisation d'IGF-1R était dépendante de la sécrétion d'IGF-2, dont l'expression est régulée par les nutriments. Finalement, nous avons démontré que la boucle autocrine IGF-2/IGF-1R est nécessaire pour le GLP-1 i) pour protéger les cellules ß contre l'apoptose induite par les cytokines, ii) pour améliorer la compétence au glucose et iii) pour augmenter la prolifération des cellules ß. Résumé tout public : Contrôle de la masse des cellules ß pancréatiques et de leur fonction par les hormones gluco-incrétines: Identification de nouveaux mécanismes régulateurs pour le traitement du diabète Chez les mammifères, la concentration de glucose sanguine (glycémie) est régulée et maintenue à une valeur relativement constante d'environ 5 mM. Cette régulation est principalement contrôlée par 2 hormones produites par les îlots pancréatiques de Langerhans: l'insuline sécrétée par les cellules ß et le glucagon sécrété par les cellules a. A la suite d'un repas, l'augmentation de la glycémie entraîne la sécrétion d'insuline ce qui permet le stockage du glucose dans le foie, les muscles et le tissu adipeux afin de diminuer le taux de glucose circulant. Lors d'un jeûne, la diminution de la glycémie permet la sécrétion de glucagon favorisant alors la production de glucose par le foie, normalisant ainsi la glycémie. Le nombre de cellules ß et leur capacité sécrétoire s'adaptent aux variations de la demande métabolique pour assurer une normoglycémie. Une destruction complète ou partielle des cellules ß conduit respectivement au diabète de type 1 et de type 2. Bien que l'augmentation de la glycémie soit le facteur stimulant de la sécrétion d'insuline, des hormones gluco-incrétines, principalement le GLP-1 (glucagon-like peptide-1) et le GIP (glucose-dependent insulinotropic polypeptide) sont libérées par l'intestin en réponse aux nutriments (glucose, acides gras) et agissent au niveau des cellules ß, potentialisant la sécrétion d'insuline induite par le glucose, stimulant leur prolifération, induisant la différentiation de cellules précurseurs en cellules ß matures et les protègent contre la mort cellulaire (apoptose). Afin d'étudier plus en détail ces mécanismes, nous avons généré des souris déficientes pour les récepteurs du GIP et du GLP-l. Les îlots pancréatiques de ces souris présentent un défaut de sécrétion d'insuline stimulée par le glucose et une sensibilité accrue à l'apoptose par rapport aux îlots de souris contrôles. Nous avons donc cherché les gènes régulés pas ces hormones contrôlant la sécrétion d'insuline et la protection contre l'apoptose. Nous avons constaté une forte diminution de l'expression du récepteur à l'IGF-1 (IGF-1R) dans les îlots de souris déficientes pour les récepteurs des gluco-incrétines. Nous avons démontré dans un model de cellules ß en culture et d'îlots que le GLP-1 augmentait l'expression d'IGF-1R et la sécrétion de son ligand (IGF-2) permettant l'activation de la voie de signalisation. Finalement, nous avons montré que l'activation de la boucle IGF-2/IGF-1R induite par le GLP-1 était nécessaire pour la protection contre l'apoptose, l'augmentation de la sécrétion et la prolifération des cellules ß.

Confirmation of natural gas explosion from methane quantification by headspace gas chromatography-mass spectrometry (HS-GC-MS) in postmortem samples: a case report.

A new analytical approach for measuring methane in tissues is presented. For the first time, the use of in situ-produced, stably labelled CDH(3) provides a reliable and precise methane quantification. This method was applied to postmortem samples obtained from two victims to help determine the explosion origin. There was evidence of methane in the adipose tissue (82 nmol/g) and cardiac blood (1.3 nmol/g) of one victim, which corresponded to a lethal methane outburst. These results are discussed in the context of the available literature to define an analysis protocol for application in the event of a gas explosion.

Main Street Messenger, Summer 2001

Newsletter for Economic Development

Main Street Messenger, Spring, 2002

Newsletter for Economic Development

Main Street Messenger, Autumn 2002

Newsletter for Economic Development

Non-medical prescription drug and illicit street drug use among young Swiss men and associated mental health issues.

Non-medical use of prescription drugs (NMUPD) is increasing among the general population, particularly among teenagers and young adults. Although prescription drugs are considered safer than illicit street drugs, NMUPD can lead to detrimental consequences. The aim of the present study was to investigate the relationship between drug use (NMUPD on the one side, illicit street drugs on the other side) with mental health issues and then compare these associations. A representative sample of 5719 young Swiss men aged around 20 years filled in a questionnaire as part of the ongoing baseline Cohort Study on Substance Use Risk Factors (C-SURF). Drug use (16 illicit street drugs and 5 NMUPDs, including sleeping pills, sedatives, pain killers, antidepressants, stimulants) and mental health issues (depression, SF12) were assessed. Simple and multiple linear regressions were employed. In simple regressions, all illicit and prescription drugs were associated with poorer mental health. In multiple regressions, most of the NMUPDs, except for stimulants, were significantly associated with poorer mental health and with depression. On the contrary, the only associations that remained significant between illicit street drugs and mental health involved cannabis. NMUPD is of growing concern not only because of its increasing occurrence, but also because of its association with depression and mental health problems, which is stronger than the association observed between these problems and illicit street drug use, excepted for cannabis. Therefore, NMUPD must be considered in screening for substance use prevention purposes.

Review of Alternative Distribution Methodologies for the Street Construction Fund of the Cities, December 26, 2003

Review of Alternative Distribution Methodologies for the Street Construction Fund of the Cities

Response-to-comments about: "Is it really the method for carbon dioxide determination in human postmortem cardiac gas samples using Headspace-Gas Chromatography-Mass Spectrometry valid?" from T. Saffaj and B. Ihssane

Saffaj et al. recently criticized our method of monitoring carbon dioxide in human postmortem cardiac gas samples using Headspace-Gas Chromatography-Mass Spectrometry. According to the authors, their demonstration, based on the latest SFSTP guidelines (established after 2007 [1,2]) fitted for the validation of drug monitoring bioanalytical methods, has put in evidence potential errors. However, our validation approach was built using SFSTP guidelines established before 2007 [3-6]. We justify the use of these guidelines because of the post-mortem context of the study (and not clinical) and the gaseous state of the sample (and not solid or liquid). Using these guidelines, our validation remains correct.

Suboptimal access to primary healthcare among street-based sex workers in southwest Switzerland.

OBJECTIVES: Street-based sex workers (SSWs) in Lausanne, Switzerland, are poorly characterised. We set out to quantify potential vulnerability factors in this population and to examine SSW healthcare use and unmet healthcare requirements. METHODS: We conducted a cross-sectional questionnaire-based survey among SSWs working in Lausanne's red light district between 1 February and 31 July 2010, examining SSW socio-demographic characteristics and factors related to their healthcare. RESULTS: We interviewed 50 SSWs (76% of those approached). A fifth conducted their interviews in French, the official language in Lausanne. 48 participants (96%) were migrants, of whom 33/48 (69%) held no residence permit. 22/50 (44%) had been educated beyond obligatory schooling. 28/50 (56%) had no health insurance. 18/50 (36%) had been victims of physical violence. While 36/50 (72%) had seen a doctor during the preceding 12 months, only 15/50 (30%) were aware of a free clinic for individuals without health insurance. Those unaware of free services consulted emergency departments or doctors outside Switzerland. Gynaecology, primary healthcare and dental services were most often listed as needed. Two individuals (of 50, 4%) disclosed positive HIV status; of the others, 24/48 (50%) had never had an HIV test. CONCLUSIONS: This vulnerable population comprises SSWs who, whether through mobility, insufficient education or language barriers, are unaware of services they are entitled to. With half the participants reporting no HIV testing, there is a need to enhance awareness of available facilities as well as to increase provision and uptake of HIV testing.

Urinary analysis of four testosterone metabolites and pregnanediol by gas chromatography-combustion-isotope ratio mass spectrometry after oral administrations of testosterone.

The most frequently used method to demonstrate testosterone abuse is the determination of the testosterone and epitestosterone concentration ratio (T/E ratio) in urine. Nevertheless, it is known that factors other than testosterone administration may increase the T/E ratio. In the last years, the determination of the carbon isotope ratio has proven to be the most promising method to help discriminate between naturally elevated T/E ratios and those reflecting T use. In this paper, an excretion study following oral administration of 40 mg testosterone undecanoate initially and 13 h later is presented. Four testosterone metabolites (androsterone, etiocholanolone, 5 alpha-androstanediol, and 5 beta-androstanediol) together with an endogenous reference (5 beta-pregnanediol) were extracted from the urines and the delta(13)C/(12)C ratio of each compound was analyzed by gas chromatography-combustion-isotope ratio mass spectrometry. The results show similar maximum delta(13)C-value variations (parts per thousand difference of delta(13)C/(12)C ratio from the isotope ratio standard) for the T metabolites and concomitant changes of the T/E ratios after administration of the first and the second dose of T. Whereas the T/E ratios as well as the androsterone, etiocholanolone and 5 alpha-androstanediol delta(13)C-values returned to the baseline 15 h after the second T administration, a decrease of the 5 beta-androstanediol delta-values could be detected for over 40 h. This suggests that measurements of 5 beta-androstanediol delta-values allow the detection of a testosterone ingestion over a longer post-administration period than other T metabolites delta(13)C-values or than the usual T/E ratio approach.

Conférence des alliés à Downing street, résidence de M. Lloyd George, le maréchal Foch et le général Weygand quittant Downing street : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57998