Sur une publication de P. Ribenboim

Sans résumé     

Isoguanosine derivatives from the Northeastern Atlantic sponge Clathria (Microciona) strepsitoxa

After a chemical screening of subtidal sponges from the Northeastern Atlantic, Clathria (Microciona) strepsitoxa (Poecilosclerida: Microcionidae) was selected for deeper investigation. This first chemical study led to the identification of two new 8-oxoisoguanosine derivatives. The structure elucidation was performed after extensive analyses of spectroscopic (1D and 2D NMR) and HR-ESIMS data and no significant antimicrobial or cytotoxic activity was detected.     

A new method to study the fiber-matrix interface in unidirectional composite materials: Application for carbon fiber-epoxy composites

Numerous studies have been done on the nature of the fiber-matrix interface and on the role of this interface in mechanical properties of epoxy-carbon fiber composite materials. In this study, we describe a new test to study the fiber-matrix interface in unidirectional composites by dynamic shear testing along the fiber axis. This method, based on three scans with increased dynamic displacement amplitude, enables us to study the recovery of mechanical properties and appearance of damage in the material. For carbon fiber-epoxy unidirectional composite materials, it is possible to distinguish two ranges in the amplitude of dynamic displacement: a first for which a recovery for G′ and tan σ is observed and a second for which permanent damage appears. The influences of fiber surface treatments such as oxidation and/or sizing on dynamic behavior are clearly displayed by this test.     

Growth kinetic of single and double-walled aluminogermanate imogolite-like nanotubes: an experimental and modeling approach

Atomic Force Microscopy (AFM) and in situ Small Angle X-ray Scattering (SAXS) were used to investigate the evolution of the aluminogermanate imogolite-like nanotubes concentration and morphology during their synthesis. In particular, in situ SAXS allowed quantifying the transformation of protoimogolite into nanotubes. The size distribution of the final nanotubes was also assessed after growth by AFM. A particular attention was focused on the determination of the single and double walled nanotube length distributions. We observed that the two nanotube types do not grow with the same kinetic and that their final length distribution was different. A model of protoimogolites oriented aggregation was constructed to account for the experimental growth kinetic and the length distribution differences.     

Development and validation of a multiplex UHPLC‐MS/MS assay with stable isotopic internal standards for the monitoring of the plasma concentrations of the antiretroviral drugs bictegravir,cabotegravir, doravirine,and rilpivirine in people living with HIV

The widespread use of highly active antiretroviral treatments has dramatically changed the prognosis of people living with HIV (PLWH). However, such treatments have to be taken lifelong raising issues regarding the maintenance of both therapeutic effectiveness and long‐term tolerability. Recently approved or investigational antiretroviral drugs present considerable advantages, allowing once daily oral dosage along with activity against resistant variants (eg, bictegravir and doravirine) and also parenteral intramuscular administration that facilitates treatment adherence (eg, long‐acting injectable formulations such as cabotegravir and rilpivirine). Still, there remains a risk of insufficient or exaggerated circulating exposure due to absorption issues, abnormal elimination, drug‐drug interactions, and others. In this context, a multiplex ultra‐high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC‐MS/MS) bioassay has been developed for the monitoring of plasma levels of bictegravir, cabotegravir, doravirine, and rilpivirine in PLWH. A simple and convenient protein precipitation was performed followed by direct injection of the supernatant into the UHPLC‐MS/MS system. The four analytes were eluted in less than 3 minutes using a reversed‐phase chromatography method coupled with triple quadrupole mass spectrometry detection. This bioassay was fully validated following international guidelines and achieved good performances in terms of trueness (94.7%‐107.5%), repeatability (2.6%‐11%), and intermediate precision (3.0%‐11.2%) over the clinically relevant concentration ranges (from 30 to 9000 ng/mL for bictegravir, cabotegravir, and doravirine and from 10 to 1800 ng/mL for rilpivirine). This sensitive, accurate, and rapid UHPLC‐MS/MS assay is currently applied in our laboratory for routine therapeutic drug monitoring of the oral drugs bictegravir and doravirine and is also intended to be applied for the monitoring of cabotegravir/rilpivirine levels in plasma from PLWH receiving once monthly or every 2‐month intramuscular injection of these long‐acting antiretroviral drugs.     

Sur le dosage de chlorure en présence d'hypochlorite,chlorite et chlorate alcalins

A method has been developed for determining the chloride anion with silver nitrate in presence of the hypochlorite, chlorite and chlorate anions.The chlorate anion does not interfere with the determination. In the presence of chlorite anions the figures for Cl' are too low in acid media.The hypochlorite anion should be reduced to the Cl' anion by PENOT'S solution.