Sample Entropy as a Tool to Assess Lumbo-Pelvic Movements in a Clinical Test for Low-Back-Pain Patients

Low back pain (LBP) obviously reduces the quality of life but is also the world’s leading cause of years lived with disability. Alterations in motor response and changes in movement patterns are expected in LBP patients when compared to healthy people. Such changes in dynamics may be assessed by the nonlinear analysis of kinematical time series recorded from one patient’s motion. Since sample entropy (SampEn) has emerged as a relevant index measuring the complexity of a given time series, we propose the development of a clinical test based on SampEn of a time series recorded by a wearable inertial measurement unit for repeated bending and returns (b and r) of the trunk. Twenty-three healthy participants were asked to perform, in random order, 50 repetitions of this movement by touching a stool and another 50 repetitions by touching a box on the floor. The angular amplitude of the b and r movement and the sample entropy of the three components of the angular velocity and acceleration were computed. We showed that the repetitive b and r “touch the stool” test could indeed be the basis of a clinical test for the evaluation of low-back-pain patients, with an optimal duration of 70 s, acceptable in daily clinical practice.     

Design of Oligourea-Based Foldamers with Antibacterial and Antifungal Activities

There is an urgent need to develop new therapeutic strategies to fight the emergence of multidrug resistant bacteria. Many antimicrobial peptides (AMPs) have been identified and characterized, but clinical translation has been limited partly due to their structural instability and degradability in physiological environments. The use of unnatural backbones leading to foldamers can generate peptidomimetics with improved properties and conformational stability. We recently reported the successful design of urea-based eukaryotic cell-penetrating foldamers (CPFs). Since cell-penetrating peptides and AMPs generally share many common features, we prepared new sequences derived from CPFs by varying the distribution of histidine- and arginine-type residues at the surface of the oligourea helix, and evaluated their activity on both Gram-positive and Gram-negative bacteria as well as on fungi. In addition, we prepared and tested new amphiphilic block cofoldamers consisting of an oligourea and a peptide segment whereby polar and charged residues are located in the peptide segment and more hydrophobic residues in the oligourea segment. Several foldamer sequences were found to display potent antibacterial activities even in the presence of 50% serum. Importantly, we show that these urea-based foldamers also possess promising antifungal properties.     

Rapid access to structured triacylglycerols acylated with n-3 polyunsaturated fatty acids for nutritional applications

In order to better understand the metabolic fate of n-3 polyunsaturated fatty acids (PUFAs), an efficient access to symmetrical and unsymmetrical triacylglycerols (TGs), esterified with PUFAs, with known high purity, is required. In this context, we optimized the esterification of a mixture of glycerols protected as dioxane and dioxolane with PUFAs. The kinetics of this reaction depends on various factors, such as the fatty acid chain length and the stereochemistry of the dioxane. Then, one-pot acetal hydrolysis and esterification of hydroxyl groups led to the desired structured TGs without either double bond isomerization or acyl migration (except when symmetrical TGs are acylated with long-chain saturated fatty acids in external positions). PUFAs location on the glycerol backbone was assayed by NMR, HPLC and pancreatic lipase hydrolysis.     

Synthesis and evaluation of an Iejimalide-archazolid chimera

Even though the macrolides of the iejimalide family are of marine origin, whereas those of the archazolid series derive from terrestrial myxobacteria, a comparison of their constitution, stereochemistry, and biological activity suggests that these natural products are close structural and functional relatives. Guided by this perception, compound 5 was prepared, which hybridizes the macrolactone core of iejimalide B (2) with the tail of archazolid A (3). The cytotoxicity profile of this chimera, as determined with a panel of 12 human cancer cell lines, corresponds to that of the parent compound 2, although its potency is lower. This outcome may be interpreted on the basis of molecular dynamics calculations, which suggest that the low energy conformations of 2 and 5 are similar but the energetic barriers between the relevant conformers are distinctly higher for the hybrid structure. The synthesis of 5 hinged on a regioselective functionalization of 2,4-dibromothiazole 6, a highly selective CBS-reduction of ketone 8, a Suzuki cross coupling of vinyl boronate 17 with the elaborate alkenyl iodide 16, and a productive closure of the macrocycle by RCM, which requires the selective activation of two out of eight double bonds present in the cyclization precursor 20 by the second-generation Grubbs catalyst 21.     

Combined analysis by GC (RI), GC-MS and 13C NMR of the supercritical fluid extract of Abies alba twigs

Two samples (leaves and twigs) of Abies alba Miller from Corsica were extracted using supercritical CO2 and their chemical compositions were compared with those of the essential oils obtained from the same batch of plant material. In total 45 components were identified using combined analysis by GC (RI), GC-MS and 13C NMR. It was observed that the contents of monoterpenes (mainly represented by limonene, alpha-pinene and camphene) were significantly lower in the supercritical fluid extract (SFE) than in the essential oil (EO). Conversely, the proportions of sesquiterpenes were much higher in CO2 extracts than in essential oils (around 30% vs 4%). Cis-abienol, a diterpene alcohol, was identified only in SFE, and the proportions of this constituent (7.5% and 17.3%) were determined using quantitative 13C NMR since it was under estimated using the standard conditions of GC.     

Extended triphenylamine conjugated systems derivatized by perfluorophenyl groups

Two triphenylamine derivatives bearing terminal perfluorophenyl groups have been synthesized. Their HOMO, LUMO levels and electronic band gap have been evaluated by spectroscopic and electrochemical measurements and rationalized with theoretical calculations. X-ray structure analysis of crystals allowed the observation of multiple intermolecular interactions due to the presence of the perfluorophenyl pendant groups. The multiplication of these interactions explains the differences between calculated (in gas phase) and observed (in solid states) structures.     

Non-invasive vibrational SFG spectroscopy reveals that bacterial adhesion can alter the conformation of grafted "brush" chains on SAM

Understanding bacterial adhesion on a surface is a crucial step to design new materials with improved properties or to control biofilm formation and eradication. Sum Frequency Generation (SFG) vibrational spectroscopy has been employed to study in situ the conformational response of a self-assembled monolayer (SAM) of octadecanethiol (ODT) on a gold film to the adhesion of hydrophilic and hydrophobic ovococcoid model bacteria. The present work highlights vibrational SFG spectroscopy as a powerful and unique non-invasive biophysical technique to probe and control bacteria interaction with ordered surfaces. Indeed, the SFG vibrational spectral changes reveal different ODT SAM conformations in air and upon exposure to aqueous solution or bacterial adhesion. Furthermore, this effect depends on the bacterial cell surface properties. The SFG spectral modeling demonstrates that hydrophobic bacteria flatten the ODT SAM alkyl chain terminal part, whereas the hydrophilic ones raise this ODT SAM terminal part. Microorganism-induced alteration of grafted chains can thus affect the desired interfacial functionality, a result that should be considered for the design of new reactive materials.     

Fluorescent nanocrystals grown in sol–gel thin films for generic stable and sensitive sensors

Through the sol–gel route, we have well-controlled the preparation of fluorescent organic nanocrystals grown in silicate thin films. This process is based on the confined nucleation and growth of dyes in the pores of wet gels. The resulting nanocomposite sol–gel thin films, coated onto low-cost substrates, exhibit coupled properties: transparency, stability, easy shaping of sol–gel thin films and high fluorescence intensity coming from organic nanocrystals. The sensitivity of the fluorescence intensity of nanocrystals to their environments can be exploited for the development of optical sensors. Indeed, Förster Resonance Energy Transfer can inhibit nanocrystal fluorescence when probe molecules are adsorbed or grafted on the nanocrystal surface after their diffusion through the pores of the sol–gel matrix. We investigated by time-resolved fluorescence spectroscopy the effect of nanocrystal size and probe concentration on the fluorescence quenching in presence of Methylene Blue used in this study as molecular probe. As strong fluorescence quenchings can be achieved, even for low probe concentrations, these hybrid organic–inorganic nanocoposites are promising for the development of sensor devices by increasing their fluorescence contrasts under specific chemical or biological environments.