A DBS method for quantitation of the new oral trypanocidal drug fexinidazole and its active metabolites.

AIM: Fexinidazole (FEX) is a nitroimidazole being developed as a new trypanocide treatment for human African trypanosomiasis/sleeping sickness. Its main metabolites, fexinidazole sulfoxide (M1) and fexinidazole sulfone (M2), show the same in vitro pharmacological activity as FEX. METHODS & RESULTS: An LC-MS/MS assay was developed for quantitation of FEX in DBS, collected via finger-prick from healthy subjects. The DBS assay was specific, accurate and reproducible for FEX, M1 and M2 when validated against the current plasma assay. DBS samples were stable for 24 h at 37°C with 95% relative humidity, and 58 weeks desiccated at room temperature. CONCLUSION: DBS finger-prick sampling offers a simple, practical method for determining FEX, M1 and M2 concentrations in clinical studies in Africa.

Model averaging inconcentration-QT analyses.

This article describes how a frequentist model averaging approach can be used for concentration-QT analyses in the context of thorough QTc studies. Based on simulations, we have concluded that starting from three candidate model families (linear, exponential, and Emax) the model averaging approach leads to treatment effect estimates that are quite robust with respect to the control of the type I error in nearly all simulated scenarios; in particular, with the model averaging approach, the type I error appears less sensitive to model misspecification than the widely used linear model. We noticed also few differences in terms of performance between the model averaging approach and the more classical model selection approach, but we believe that, despite both can be recommended in practice, the model averaging approach can be more appealing because of some deficiencies of model selection approach pointed out in the literature. We think that a model averaging or model selection approach should be systematically considered for conducting concentration-QT analyses. Copyright © 2016 John Wiley & Sons, Ltd.

Lixisenatide reduces postprandial hyperglycaemia via gastrostatic and insulinotropic effects.

BACKGROUND: Lixisenatide is a once-daily, prandial, short-acting glucagon-like peptide-1 receptor agonist. Its main antidiabetic effect is to delay gastric emptying to control postprandial plasma glucose excursions. The dose-response relationship of the integrated insulinotropic and gastrostatic response to lixisenatide in healthy volunteers after a standardized liquid meal was investigated. METHODS: Twenty healthy subjects received acetaminophen 1000 mg with a standardized liquid meal 60 min after a single subcutaneous injection of placebo or lixisenatide 2.5, 5, 10 or 20 µg in randomized order separated by a 2- to 7-day washout. Acetaminophen pharmacokinetics served as a surrogate to assess rate of gastric emptying. Postprandial plasma glucose, insulin, C-peptide and glucagon were assessed for 5 h after the meal test, and lixisenatide pharmacokinetics were determined for 6 h. RESULTS: After lixisenatide administration and prior to the standardized meal, insulin and C-peptide transiently increased, while fasting plasma glucose decreased in a dose-dependent manner. After the meal, postprandial plasma glucose, insulin and C-peptide were dose proportionally reduced with lixisenatide versus placebo for up to 6 h. Compared with placebo, glucagon levels were transiently lower after any lixisenatide dose, with more sustained reductions after the meal and no apparent dose-related trends. Acetaminophen absorption was significantly reduced and delayed compared with placebo for lixisenatide doses ≥5 µg and demonstrated dose-dependent slowing of gastric emptying. Lixisenatide displayed near dose-proportional exposure, with gastrointestinal events increasing with dose. CONCLUSIONS: Lixisenatide reduced fasting plasma glucose via stimulation of glucose-dependent insulin release and controlled postprandial plasma glucose by delaying gastric emptying, demonstrating it to be a valuable option for overall glycaemic control.

A metagenomic study highlights phylogenetic proximity of quorum-quenching and xenobiotic-degrading amidases of the AS-family.

Quorum-sensing (QS) signals of the N-acylhomoserine lactone (NAHL) class are cleaved by quorum-quenching enzymes, collectively named NAHLases. Here, functional metagenomics allowed the discovery of a novel bacterial NAHLase in a rhizosphere that was treated with γ-caprolactone. As revealed by rrs-DGGE and rrs-pyrosequencing, this treatment increased the percentage of the NAHL-degrading bacteria and strongly biased the structure of the bacterial community, among which Azospirillum dominated. Among the 29 760 fosmids of the metagenomic library, a single one was detected that expressed the qsdB gene conferring NAHL-degradation upon E. coli and decreased QS-regulated virulence in Pectobacterium. Phylogenetic analysis of the 34 orfs of the fosmid suggested that it would belong to an unknown Proteobacterium - probably a γ-proteobacterium. qPCR quantification of the NAHLase-encoding genes attM, qsdA, and qsdB revealed their higher abundance in the γ-caprolactone-treated rhizosphere as compared to an untreated control. The purified QsdB enzyme exhibited amidase activity. QsdB is the first amidase signature (AS) family member exhibiting NAHLase-activity. Point mutations in the AS-family catalytic triad K-S-S abolished the NAHLase activity of QsdB. This study extends the diversity of NAHLases and highlights a common phylogenic origin of AS-family enzymes involved in the degradation of natural compounds, such as NAHLs, and xenobiotics, such as nylon and linuron.

A haptic virtual environment for tele-echography.

Having a haptic virtual environment for tele-echography will enable the medical expert with faster adaptation and especially facilitated immersion in what we could call a "virtual echographic examination cabinet". The innovation of this haptic control is to preserve medical expert proprioception and gesture feelings, which provide the users with indications that are synchronized with the echographic images. In this paper, we will focus on the telegesture module: we will detail several issues and solutions related to this particular problem of tele-robotic scan examination.