Les politiques de régulation de la profession enseignante et leurs effets sur les enseignants

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0272: Unfractionated heparin addition during percutaneous coronary intervention in acute coronary syndrome patients previously treated with enoxaparin: biological impact

BackgroundThe benefit of anticoagulants (AC) to prevent thrombotic complications during percutaneous coronary intervention (PCI) is well established. In acute coronary syndrome (ACS) patients previously treated with enoxaparin, an additional bolus of AC is not recommended if the last injection was realized within 8 h. In this setting, many interventional cardiologists use unfractionated heparin (UFH) at the time of sheath insertion.ObjectivesThe aim of our study was to describe local current practices for AC use during PCI in patients already treated with enoxaparin and admitted for ACS and to assess the biological impact of UFH addition at the beginning of the procedure.MethodsA standardized survey was sent to the interventional cardiologists of the southwest of France to investigate their practice in terms of periprocedural AC use. In 2 centers, ACS patients previously treated with subcutaneous injection of enoxaparin within 8 h and who received intravenous UFH at the time of sheath insertion were prospectively included and their plasma anti-Xa activity was assessed at the sheath insertion and 30 min after UFH bolus. In-hospital bleeding and ischemic events were collected. The adequate therapeutic window was defined by anti Xa activity (range 0.5 to 0.9 IU/mL). Results: Among the 41 interventional cardiologists who replied, a large majority (75,6%) considered the addition of UFH in patients who received enoxaparin within 8 h as a valid option. 47 ACS patients were enrolled. The dose of the bolus of UFH was highly variable from 20 to 90 UI / kg. Anti-Xa activities were above 0.9 IU/mL in 14,9% of patients at the sheath insertion and in 72,3% of patients 30 min after UFH injection. 2 bleeding complications occurred, both in over-coagulated patients. No ischemic events were reported.ConclusionThe use of UFH in patients who already received enoxaparin may result in over-anticoagulation and lead to bleeding complications

The MHC class I peptide repertoire is molded by the transcriptome

Under steady-state conditions, major histocompatibility complex (MHC) I molecules are associated with self-peptides that are collectively referred to as the MHC class I peptide (MIP) repertoire. Very little is known about the genesis and molecular composition of the MIP repertoire. We developed a novel high-throughput mass spectrometry approach that yields an accurate definition of the nature and relative abundance of unlabeled peptides presented by MHC I molecules. We identified 189 and 196 MHC I–associated peptides from normal and neoplastic mouse thymocytes, respectively. By integrating our peptidomic data with global profiling of the transcriptome, we reached two conclusions. The MIP repertoire of primary mouse thymocytes is biased toward peptides derived from highly abundant transcripts and is enriched in peptides derived from cyclins/cyclin-dependent kinases and helicases. Furthermore, we found that ∼25% of MHC I–associated peptides were differentially expressed on normal versus neoplastic thymocytes. Approximately half of those peptides are derived from molecules directly implicated in neoplastic transformation (e.g., components of the PI3K–AKT–mTOR pathway). In most cases, overexpression of MHC I peptides on cancer cells entailed posttranscriptional mechanisms. Our results show that high-throughput analysis and sequencing of MHC I–associated peptides yields unique insights into the genesis of the MIP repertoire in normal and neoplastic cells

Analysis of the cell surface layer ultrastructure of the oral pathogen Tannerella forsythia

The Gram-negative oral pathogen Tannerella forsythia is decorated with a 2D crystalline surface (S-) layer, with two different S-layer glycoprotein species being present. Prompted by the predicted virulence potential of the S-layer, this study focused on the analysis of the arrangement of the individual S-layer glycoproteins by a combination of microscopic, genetic, and biochemical analyses. The two S-layer genes are transcribed into mRNA and expressed into protein in equal amounts. The S-layer was investigated on intact bacterial cells by transmission electron microscopy, by immune fluorescence microscopy, and by atomic force microscopy. The analyses of wild-type cells revealed a distinct square S-layer lattice with an overall lattice constant of 10.1 ± 0.7 nm. In contrast, a blurred lattice with a lattice constant of 9.0 nm was found on S-layer single-mutant cells. This together with in vitro self-assembly studies using purified (glyco)protein species indicated their increased structural flexibility after self-assembly and/or impaired self-assembly capability. In conjunction with TEM analyses of thin-sectioned cells, this study demonstrates the unusual case that two S-layer glycoproteins are co-assembled into a single S-layer. Additionally, flagella and pilus-like structures were observed on T. forsythia cells, which might impact the pathogenicity of this bacterium