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/)

Sequence properties of certain GC rich avian genes, their origins and absence from genome assemblies: case studies

International audienceBackground More and more eukaryotic genomes are sequenced and assembled, most of them presented as a complete model in which missing chromosomal regions are filled by Ns and where a few chromosomes may be lacking. Avian genomes often contain sequences with high GC content, which has been hypothesized to be at the origin of many missing sequences in these genomes. We investigated features of these missing sequences to discover why some may not have been integrated into genomic libraries and/or sequenced. Results The sequences of five red jungle fowl cDNA models with high GC content were used as queries to search publicly available datasets of Illumina and Pacbio sequencing reads. These were used to reconstruct the leptin, TNF alpha, MRPL52, PCP2 and PET100 genes, all of which are absent from the red jungle fowl genome model. These gene sequences displayed elevated GC contents, had intron sizes that were sometimes larger than non-avian orthologues, and had non-coding regions that contained numerous tandem and inverted repeat sequences with motifs able to assemble into stable G-quadruplexes and intrastrand dyadic structures. Our results suggest that Illumina technology was unable to sequence the non-coding regions of these genes. On the other hand, PacBio technology was able to sequence these regions, but with dramatically lower efficiency than would typically be expected. Conclusions High GC content was not the principal reason why numerous GC-rich regions of avian genomes are missing from genome assembly models. Instead, it is the presence of tandem repeats containing motifs capable of assembling into very stable secondary structures that is likely responsible

An Assessment of Fixed and Native Chromatin Preparation Methods to Study Histone Post-Translational Modifications at a Whole Genome Scale in Skeletal Muscle Tissue

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Cleavage of Occludin by Cigarette Smoke-Elicited Cathepsin S Increases Permeability of Lung Epithelial Cells

Background. Chronic obstructive pulmonary disease (COPD) is an irreversible disease mainly caused by smoking. COPD is characterized by emphysema and chronic bronchitis associated with enhanced epithelial permeability. Hypothesis. Lung biopsies from smokers revealed a decreased expression level of occludin, which is a protein involved in the cohesion of epithelial tight junctions. Moreover, the occludin level correlated negatively with smoking history (pack-years), COPD grades, and cathepsin S (CatS) activity. Thus, we examined whether CatS could participate in the modulation of the integrity of human lung epithelial barriers. Methods and results. Cigarette smoke extract (CSE) triggered the upregulation of CatS by THP-1 macrophages through the mTOR/TFEB signaling pathway. In a co-culture model, following the exposure of macrophages to CSE, an enhanced level of permeability of lung epithelial (16HBE and NHBE) cells towards FITC-Dextran was observed, which was associated with a decrease in occludin level. Similar results were obtained using 16HBE and NHBE cells cultured at the air–liquid interface. The treatment of THP-1 macrophages by CatS siRNAs or by a pharmacological inhibitor restored the barrier function of epithelial cells, suggesting that cigarette smoke-elicited CatS induced an alteration of epithelial integrity via the proteolytic injury of occludin. Conclusions. Alongside its noteworthy resistance to oxidative stress induced by cigarette smoke oxidants and its deleterious elastin-degrading potency, CatS may also have a detrimental effect on the barrier function of epithelial cells through the cleavage of occludin. The obtained data emphasize the emerging role of CatS in smoking-related lung diseases and strengthen the relevance of targeting CatS in the treatment of emphysema and COPD

Analyse bioinformatique des marques d'histone chez le poulet exposé à la chaleur pendant l'incubation

National audienc

Analyse bioinformatique des modifications post-traductionnelles des histones chez le poulet thermomanipulé durant l'embryogenèse

National audienc

Etude de l’impact de l’acclimatation embryonnaire à la chaleur du poulet de chair sur des modifications épigénétiques

Broilers genetically selected for their performance suffer from heat exposure at slaughter age (D35). In a contextof global warming, it is possible to enhance heat tolerance by heat acclimation during embryogenesis. Thetreatment consists in increasing cyclically the incubation temperature of the eggs during the embryonic days E7to E16. This heat acclimation modifies physiology, metabolism and gene expression in the long term. Thealteration of the early environment can impact gene expression by epigenetic modifications. Therefore the geneexpression variations observed at D35 could be linked to a modification of the epigenome induced by theembryonic treatment, which persists throughout development. Two post-translational modifications could beimplicated, the tri-methylation of lysine 27 on the histone H3 (H3K27me3) involved in epigenetic memory underan environmental stimulus and the tri-methylation of lysine 4 on the histone H3 (H3K4me3) linked to genetranscriptional activation. To study these marks we have adjusted the chromatin immunoprecipitation (ChIP)technique to the hypothalamus, which is the center of thermoregulation. ChIP was followed by high throughputsequencing to study without bias the differentially enriched regions between the controls and the heat acclimatedchicken. Preliminary sequencing results for the hypothalamus will be presented.Les poulets sélectionnés pour leurs performances de croissance sont sensibles aux variations de température. Le traitement d’acclimatation embryonnaire à la chaleur permet de rendre les animaux plus tolérants à la chaleur à l’âge d’abattage (J35). Ce traitement consiste à augmenter de façon cyclique la température d’incubation desoeufs entre les jours E7 et E16 de l’embryogenèse. Il modifie la physiologie, le métabolisme et l’expression desgènes à long terme. L’altération de l’environnement précoce peut avoir un impact à long terme sur l’expressiondes gènes notamment par le biais de modifications épigénétiques. Les modifications d’expression de gènesobservées chez les poulets à J35 pourraient être dues à une altération de l’épigénome induite par le traitementlors de l’embryogenèse et persistant au cours du développement. Nous étudions deux modifications posttraductionnelles des histones, la triméthylation de la lysine 27 sur l’histone H3 (H3K27me3) décrite commeayant un rôle dans la mémoire épigénétique sous l’influence de l’environnement et la triméthylation de la lysine4 sur l’histone H3 (H3K4me3) associée à des gènes transcriptionnellement actifs. Afin de caractériser cesmarques nous avons mis au point la technique d’immuno-précipitation de la chromatine (ChIP) pourl’hypothalamus, centre de la thermorégulation. Le ChIP a été suivi d’un séquençage haut débit afin dedéterminer sans a priori les régions différentiellement enrichies en ces deux marques entre les individus témoinset acclimatés. Les premiers résultats issus du séquençage sur l’hypothalamus seront présentés