Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Nano-détection du fipronil et de ses métabolites dans des matices agroalimentaires

LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Nano-détection du fipronil et de ses principaux métabolites dans diverses matrices apicoles

National audienceLe fipronil, substance active du Régent TS est utilisé pour l'enrobage des semences, notamment de maïs et de tournesol. Neurotoxique puissant, ses principaux métabolites sont également toxiques. Nous avons mis au point et validé des méthodes qui permettent de détecter et quantifier, de manière très spécifique et très sensible, le fipronil et trois de ses principaux métabolites à l'état de traces et ultra-traces dans diverses matrices du monde apicole (pollen, abeilles, miel). Après des étapes d'extraction et de purification, l'analyse a été conduite par GC-MS (seuils de détection et quantification inférieur au ng/g

Molecular characterization of petroleum mixtures using multiple ionization modes and GC×GC-HRTOFMS

Introduction: Comprehensive two-dimensional gas chromatography (GC×GC) has become a method of choice for complex mixture characterization, especially in the petroleum industry. Indeed, the high resolving power of the 2D separations offers structured separation allowing pattern recognition and group type classification of sample composition. For years, the technique was relying on electron ionization (EI) fragmentogram and chromatographic-based identification due to practical limitations on the detector side, mainly the high acquisition frequency required. The development of high-speed high-resolution time-of-flight mass spectrometers (TOFMS) offers opportunities to go deeper in the sample characterization. To obtain the most of the HRMS dimension, there is a growing interest to combine EI with softer ionization techniques, which preserve the molecular ion. Method: In this study, different base oil samples and standard mixtures were analyzed by GC×GC-HRTOMS. Three different soft-ionization techniques including photo ionization (PI), chemical ionization (CI), and field ionization (FI) were compared against EI to elucidate their relative capabilities to reveal different base oil hydrocarbon classes. Deeper investigations were also conducted on the PI fragmentation process for different chemical families. All the experiments were performed on a single system, a JEOL AccuTOF GCv 4G with modular ionization technologies. A low-polar (ZB-XLB-HT Inferno, 15.0 m, 0.25 mm ID, 0.1 μm, Phenomenex ) and polar (ZB-50HT, 2.0 m, 0.1 mm ID, 0.1 μm, Phenomenex) columns were used for base oil analysis for first and second dimension separation respectively. Preliminary Data: Compared to EI (70 eV), capabilities and limitations of PI were tested using an authentic mixture of compounds of several chemical classes. Ionization energy exhibited by PI, equivalent to 10.8 eV, resulted in significant retention of molecular ion information; [M]+• for alkanes, ketones, FAMEs, aromatics, [M−H]+• for chloroalkanes, and [M−H2O]+• for alcohols. In addition, considering the potential of PI for hydrocarbons, base oils, complex mixtures of saturated and unsaturated hydrocarbons blended for finished lubricant formulations, were extensively evaluated. PI retained significant molecular ion (M+‧) information for a large number of isomeric species including branched-alkanes and saturated mono-cyclic hydrocarbons along with unique fragmentation patterns. However, for bi-/poly cyclic naphthenic and aromatic compounds, EI played upper hand by retaining molecular as well as fragment ions to identify the species, whereas PI exhibited mainly molecular ion signals. CI revealed selectivity towards different base oil groups, particularly for steranes, sulfur-containing thiophenes, and esters; yielding protonated molecular ions (M+H) + for unsaturated and hydride abstracted ions (M-H+) for saturated hydrocarbons. FI, as expected, generated intact molecular ions (M+‧) irrespective to the base oil chemical classes. It allowed elemental composition by TOFMS with a mass resolving power up to 8,000 (FWHM) and a mass accuracy of 1 mDa, leading to the calculation of heteroatomic content, and carbon number of the compounds. The qualitative and quantitative results presented herein offer a unique perspective into the detailed comparison of different ionization techniques corresponding to several chemical classes. Novel aspect: The GC×GC field is ongoing a paradigm shift in which the MS dimension is even further contributing than before

Bees and systemic insecticides (imidacloprid, fipronil) in pollen: subnano-quantification by HPLC/MS/MS and GC/MS

International audienceImidacloprid and fipronil are two insecticides acting on the central nervous system. They are used worldwide, from the mid nineties, especially for seed coating of crops. Concomitantly to their introduction and their increasing use in French fields, honeybee populations decreased. Bee problems are nowadays reported in other countries (also called disappearing disease, desplobación de las colmenas, trouble des abeilles, deperimento degli apiari or colony collapse disorder). Bee problems have certainly several origins. Contamination of pollen and nectar by such chemicals appeared as one of the most probable cause, since subletal effects and chronic intoxications were observed on bees, at very low concentrations. We developed fully validated methods to measure contamination in pollen (sunflower and maize) for imidacloprid (HPLC/MS/MS) and for fipronil and 3 of its derivatives (GC/MS). For imidacloprid LOD and LOQ are 0.3 and 1 ng/g, respectively. For fipronil and each derivative (fiprole), LOD and LOQ are 0.07 and 0.2 ng/g, respectively. The averaged level of imidacloprid in pollen was 2-3 ng/g, which is 20-30 times higher than the concentration inducing significant mortality by chronic intoxication. Fiproles were detected in 48% of pollens issuing from treated crops. Fipronil and its sulfone derivative represented 77% and 17% of contaminants, respectively. The averaged fiprole sum Σf was 0.3 - 0.4 ng/g, which is 30-40 times higher than the concentration inducing significant mortality of bees by chronic intoxication

Combining Fourier Transform-Ion Cyclotron Resonance/Mass Spectrometry Analysis and Kendrick Plots for Silicon Speciation and Molecular Characterization in Petroleum Products at Trace Levels

A new method combining FT-ICR/MS analysis and Kendrick plots for the characterization of silicon species at trace levels in light petroleum products is presented. The method provides efficient instrumental detection limits ranging from 80 ng/kg to 5 μg/kg and reliable mass accuracy lower than 0.50 ppm for model silicon molecules in spiked gasoline. More than 3000 peaks could be detected in the <i>m</i>/<i>z</i> 50–500 range depending on the nature of the gasoline sample analyzed. An in-house software program was used to calculate Kendrick plots. Then, an algorithm searched, selected, and represented silicon species classes (O₂Si, O₃Si, and O₄Si classes) in Kendrick plots by incorporating model molecules' information (i.e., exact mass and intensity). This procedure allowed the complete characterization of more than 50 new silicon species with different degrees of unsaturation in petroleum products

Hydrothermal conversion of glucose in a batch reactor. A detailed study of an experimental key-parameter : the heating time

n this study, conversions of an aqueous solution of glucose (2 wt%) were performed at 370 °C and 25 MPa in subcritical water during different heating times. The original batch reactor used for this study allowed the introduction of the glucose solution directly in the hot and compressed aqueous medium. In this work, an original analytical approach combining chromatographic (SEC, GC, HPLC) and mass spectrometric techniques (FT-ICR/MS) has been also developed in order to provide more information about the chemical and molecular weights polydispersity of the products. From our experiments, it has been shown that the glucose conversion occurs via a complex reaction pathway implying competitive fragmentation and condensation reactions. Yields of product resulting from condensation reactions can be limited mainly by both short heating time and reaction time