SARS-CoV-2 spike glycoprotein mediates receptor binding and subsequent membrane fusion. It exists in a range of conformations, including a closed state unable to bind the ACE2 receptor, and an open state that does so but displays more exposed antigenic surface. Spikes of variants of concern (VOCs) acquired amino acid changes linked to increased virulence and immune evasion. Here, using HDX-MS, we identified changes in spike dynamics that we associate with the transition from closed to open conformations, to ACE2 binding, and to specific mutations in VOCs. We show that the RBD-associated subdomain plays a role in spike opening, whereas the NTD acts as a hotspot of conformational divergence of VOC spikes driving immune evasion. Alpha, beta and delta spikes assume predominantly open conformations and ACE2 binding increases the dynamics of their core helices, priming spikes for fusion. Conversely, substitutions in omicron spike lead to predominantly closed conformations, presumably enabling it to escape antibodies. At the same time, its core helices show characteristics of being pre-primed for fusion even in the absence of ACE2. These data inform on SARS-CoV-2 evolution and omicron variant emergence.

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A liquid chromatography-tandem mass spectrometry method was developed and used to simultaneously detect 19 small peptide hormones prohibited in sport and their main metabolites in urine after solid-phase extraction. Detection was achieved using a triple-quadrupole mass spectrometric detector coupled with an electrospray ionization interface after chromatographic separation with an octadecyl column based on fused-core particle technology. Sample pretreatment was performed by solid-phase extraction. The extraction procedure was optimized by comparison of different sorbents and washing/elution protocols. The best results were obtained using a mixed-mode weak cation exchange sorbent, two washing steps (ultrapurified water and methanol), and elution using 300 mM ammonium formate in 25 % ammonia/methanol (10/90) or 25 % ammonia/10 % formic acid/methanol (8/12/80). The procedure was validated in terms of sensitivity (lower limits of detection: 0.05-2.0 ng/ml depending on the target analyte), specificity, recovery [[60 %, coefficient of variation (CV) \15 % except for TB500 17-23 fragment, AOD9604, and ARA290 for which recovery was \50 %), ion suppression/enhancement (\35 %), robustness, carryover, stability of the target analytes [stable for at least for 2 days (25°C, 2 weeks (4°C), 2 months (-20°C)], and repeatability of retention times (CV \0.1 %) and relative abundances of the selected ion transitions (CV \15 %).The suitability of the method was confirmed by analyzing spiked and excreted urines, the latter collected after intravenous injection of 0.1 mg of GHRP-2.

This study provides evidence of proven fetal exposure to ethanol during the second and third trimesters of pregnancy by linking detection of ethanol biomarkers (EtG) in maternal hair segments and EtG in neonatal meconium.

In a prospective sample of 80 mother-infant dyads, we investigated whether drugs of abuse in maternal hair measured during the pregnancy trimesters were also present in neonatal meconium. Principal drugs of abuse were analyzed in the three consecutive maternal hair segments and meconium samples by ultra-performance liquid chromatography tandem mass spectrometry assay. Of the 80 mothers, 32 (40%) presented one or more hair shafts with at least one of the analyzed drugs of abuse and/or its metabolites. The drug of abuse with a higher prevalence in our study population was methamphetamine: 19 mothers had methamphetamine in one or more hair segments (59.4%). The second most detected drug of abuse was cocaine; nine mothers presented cocaine in one or more hair segments (28.1%). Nineteen pregnant women consumed at least one drug of abuse during the first trimester, ten continued consuming drugs of abuse during the second trimester; and nine consumed until the end of pregnancy. Five of the nine newborns from mothers who consumed drugs during the whole pregnancy showed drugs of abuse in meconium samples. Newborns from the 23 remaining mothers with one or two hair shafts positive to drugs of abuse did not present drugs in their meconium. Indeed from these results, it seems that discontinuous and/or sporadic consumption during pregnancy could produce a negligible transplacental passage and hence negative results in meconium. Furthermore, the role of placenta in the metabolism and excretion of drugs of abuse is still to be precisely investigated. Copyright © 2015 John Wiley & Sons, Ltd.