Increasing the effectiveness of intracerebral injections in adult and neonatal mice: a neurosurgical point of view

International audienceIntracerebral injections of tracers or viral constructs in rodents are now commonly used in the neurosciences and must be executed perfectly. The purpose of this article is to update existing protocols for intracerebral injections in adult and neonatal mice. Our procedure for stereotaxic injections in adult mice allows the investigator to improve the effectiveness and safety, and save time. Furthermore, for the first time, we describe a two-handed procedure for intracerebral injections in neonatal mice that can be performed by a single operator in a very short time. Our technique using the stereotaxic arm allows a higher precision than freehand techniques previously described. Stereotaxic injections in adult mice can be performed in 20 min and have >90% efficacy in targeting the injection site. Injections in neonatal mice can be performed in 5 min. Efficacy depends on the difficulty of precisely localizing the injection sites, due to the small size of the animal. We describe an innovative, effortless, and reproducible surgical protocol for intracerebral injections in adult and neonatal mice

Caractérisation, identification et quantification de biomarqueurs et principes actifs dans des compléments alimentaires ou des phytopréparations

Les compléments alimentaires ne sont pas soumis à des contrôles qualités stricts et sont facilement accessibles. Partant de ces constatations, le Service de la consommation et des affaires vétérinaires de Genève fait régulièrement des campagnes d'analyses pour vérifier la qualité et l'innocuité de ces produits, en particulier les produits à base de plantes. Pour limiter le nombre d'analyses, une méthode LC-MS/MS générique et évolutive a été développée afin d'identifier un maximum de végétaux (90 plantes en juin 2014) en une seule analyse de 15 minutes. Pour cela, chaque plante a été associée à un ou plusieurs biomarqueurs, caractérisés par un temps de rétention, deux transitions de masse et trois spectres de masse générés à trois énergies de collision. Parallèlement à cette méthode générique, plusieurs méthodes spécifiques ont été mises au point et validées afin de détecter et quantifier des toxines naturelles. Des alcaloïdes pyrrolizidiniques hépatotoxiques ont été recherchés dans des thés et infusions dans le but d'étayer une évaluation des risques menée par l'Office fédéral de la sécurité alimentaire et des affaires vétérinaires. Une autre méthode a été développée pour extraire et quantifier une toxine naturelle dans des anis étoilés. Différentes techniques de séparations chromatographiques et de détection (TOF-HRMS, TOF-HSMS, MS/MS) ont été utilisées pour confirmer la présence de caféine, et la quantifier dans des infusions à base de tilleul. Enfin, une technique de détection et de quantification par HPTLC couplée à la spectrophotométrie UV a été développée pour doser la sibutramine dans des compléments amaigrissants

Unexpected Occurrence of Caffeine in Sleep-Inducing Herbal Teas

Caffeine acts as a weak psychostimulant and is known to cause trouble with sleeping. Therefore, the presence of caffeine in sleep-aid herbal teas was somewhat surprising, and confirmatory investigations were conducted to exclude any possible misidentification. The botanicals of the sedative mixtures were analysed individually by ultra performance liquid chromatography (UPLC) coupled with a time-of-flight high-resolution mass spectrometer (TOF-HRMS), and caffeine was detected in linden (Tilia spp.) extracts. The presence of caffeine was unambiguously confirmed by means of its characteristic mass spectrum acquired during direct analyses of powdered linden by thermal desorption coupled to a GC×GC-TOF-MS. Caffeine content was determined in 11 linden-based samples, with a validated UPLC-MS/MS method using two mass transitions. Concentrations were between traces and 110 mg kg–1 in the herbal material while those in the corresponding prepared sleep-inducing hot beverages ranged from traces to 226 μg per cup

Survey of pyrrolizidine alkaloids in teas and herbal teas on the Swiss market using HPLC-MS/MS

Pyrrolizidine alkaloids (PAs) are a large class of natural compounds amongst which the esterified 1,2-unsaturated necine base is toxic for humans and livestock. In the present study, a method was developed and validated for the screening and quantification of nine PAs and one PA N-oxide in teas (Camellia sinensis (L.) O. Kuntze) and herbal teas (camomile, fennel, linden, mint, rooibos, verbena). Samples were analysed by HPLC on a RP-column, packed with sub-2 μm core-shell particles, and quantified using tandem mass spectrometry operating in the positive electrospray ionisation mode. These PAs and some of their isomers were detected in a majority of the analysed beverages (50/70 samples). In 24 samples, PA concentrations were above the limit of quantification and the sum of the nine targeted PAs was between 0.021 and 0.954μg per cup of tea. Thus, in some cases, total concentrations exceed the maximum daily intake recommended by the German Federal Institute for Risk Assessment and the UK’s Committee On Toxicity (i.e. 0.007 μgkg−1 bw)

Iron‐biomineralizing organelle in magnetotactic bacteria: function, synthesis and preservation in ancient rock samples

International audienc

HPTLC determination of sibutramine in adulterated herbal slimming supplements

To detect and quantify sibutramine in herbal slimming supplements an HPTLC-UV densitometry method was developed. This method allows for simple, fast and accurate analysis of complex mixtures. For confirmation of positive results by mass spectrometry a TLC-MS interface was used to elute target zones from the HPTLC plate; this was especially useful for samples with low sibutramine concentration

Screening and determination of sibutramine in adulterated herbal slimming supplements by HPTLC-UV densitometry

The adulteration of herbal supplements is of growing importance, especially when they contain undeclared compounds like sibutramine that are unsafe drugs. Sibutramine was withdrawn from US and European markets in 2010. In this study, an HPTLC-UV densitometric method was developed for the quantification of sibutramine in herbal diet foods. Sample extracts were directly applied onto HPTLC silica gel plates and separated with a mobile phase made of a toluene-methanol mixture. Sibutramine was quantified at 225 nm and its unequivocal identification was confirmed by mass spectrometry using a TLC-MS interface. During two surveys, 52 weight loss supplements obtained via the Internet were screened. Half of those were adulterated with sibutramine at amounts reaching up to 35 mg per capsule. The results of this validated HPTLC method were compared with those obtained by HPLC-UV and HPLC-MS/MS. The concentrations were not significantly different with the three methods

Analysis of the neurotoxin anisatin in star anise by LC-MS/MS

The aim of this work was to develop an analytical method capable of determining the presence of anisatin in star anise. This neurotoxin may induce severe side effects such as epileptic convulsions. It is therefore of prime importance to have rapid and accurate analytical methods able to detect and quantify anisatin in samples that are purportedly edible star anise. The sample preparation combined an automated accelerated solvent extraction with a solid-supported liquid-liquid purification step on EXtrelut®. Samples were analysed on a porous graphitic carbon HPLC column and quantified by tandem mass spectrometry operating in the negative ionisation mode. The quantification range of anisatin was between 0.2 and 8 mg kg−1. The applicability of this validated method was demonstrated by the analysis of several Illicium species and star anise samples purchased on the Swiss market. High levels of anisatin were measured in Illicium lanceolatum, I. majus and I. anisatum, which may cause health concerns if they are misidentified or mixed with edible Illicium verum