====== Annexin A5 ======
 

[[Annexin A5]] (or [[annexin]] V) is a cellular protein in the [[annexin]] group. In [[flow cytometry]], annexin V is commonly used to detect apoptotic cells by its ability to bind to phosphatidylserine, a marker of [[apoptosis]] when it is on the outer leaflet of the plasma membrane. The function of the protein is unknown; however, annexin A5 has been proposed to play a role in the inhibition of blood [[coagulation]] by competing for phosphatidylserine binding sites with [[prothrombin]] and also to inhibit the activity of phospholipase A1. These properties have been found by in vitro experiments.

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[[Primary brain tumor]]s are associated with an increased risk of [[pulmonary embolism]] (PE), particularly in the early post-operative period. The pathophysiological mechanisms of PE are poorly understood. 
A study aimed to describe prospectively [[extracellular vesicle]]s (EVs) levels and investigate whether or not their variations allow to identify patients at increased risk of post-operative PE. Consecutive [[meningioma]] or [[glioma]] patients candidate to [[tumor resection]] were included in the study if a pulmonary perfusion scan ([[V/Q scan]]) performed before surgery ruled out PE. EVs derived from [[platelet]]s ([[CD41]]+) or endothelial cells ([[CD144]]+), tissue factor-bearing EVs ([[CD142]]+) and their procoagulant subtype ([[Annexin A5]]) were analyzed by [[flow cytometry]] before surgery (T0), within 24 h (T1), two (T2) and seven days (T7) after surgery. Q-scan was repeated at T2. Ninety-three patients with meningioma, 59 with glioma and 76 healthy controls were included in the study. CD142+ and annexin V+/CD142+ EVs were increased at T0 in meningioma and glioma patients compared to healthy controls. Twenty-nine meningioma (32%) and 16 glioma patients (27%) developed PE at T2. EVs levels were similar in meningioma patients with or without PE, whereas [[annexin]] V+ and annexin V+/CD142+ EVs were significantly higher at T1 and T2 in glioma patients with PE than in those without. Procoagulant EVs, particularly [[annexin]] V+/CD142+, increase after surgery and are more prevalent in glioma patients who developed PE after surgery than in those who did not
((Passamonti SM, Artoni A, Carrabba G, Merati G, Abbattista M, Capecchi M, Castellani M, Marenghi C, Trombetta E, Giammattei L, Caroli M, Bucciarelli P, Scalambrino E, Peyvandi F, Martinelli I. Plasma levels of [[extracellular vesicle]]s and the risk of post-operative [[pulmonary embolism]] in patients with [[primary brain tumor]]s: a prospective study. J Thromb Thrombolysis. 2021 Apr 10. doi: 10.1007/s11239-021-02441-3. Epub ahead of print. PMID: 33837918.)).