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Concept

Coagulation sanguine

Résumé

La coagulation sanguine est un processus complexe aboutissant à la formation de caillots sanguins. C’est une partie importante de l’hémostase où la paroi endommagée d’un vaisseau sanguin est couverte d’un caillot de fibrine, ce qui a pour conséquence d'arrêter l’hémorragie. Les troubles de la coagulation qui mènent à des risques de saignements plus importants sont appelés hémophilie. D'autres troubles de la coagulation peuvent mener à un plus grand risque de thrombose. La coagulation est remarquablement préservée d'une espèce à l'autre : chez tous les mammifères, elle repose sur la formation d'un clou plaquettaire et sur une composante protéique de coagulation (ce sont les facteurs de coagulation). Dans les années 1960 Davie, Ratnoff et Macfarlane décrivent le concept de la coagulation en la nommant ou . Ils décrivent le principe fondamental de la cascade de proenzymes menant à l'activation des enzymes en aval. La coagulation débute presque instantanément après une brèche au nive

Source officielle

https://fr.wikipedia.org/wiki/Coagulation_sanguine

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La thrombose est la formation d'un caillot (thrombus) dans une veine ou une artère obstruant la circulation du sang dans le système circulatoire. Articles connexes

Thrombose veineuse

thumb|300px|De gauche à droite : érythrocyte (globule rouge), thrombocyte activé (noter les spiculations) (plaquette), leucocyte (globule blanc), en microscopie électronique à balayage en fausse coule

Thrombin (, fibrinogenase, thrombase, thrombofort, topical, thrombin-C, tropostasin, activated blood-coagulation factor II, blood-coagulation factor IIa, factor IIa, E thrombin, beta-thrombin, gamma

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Ce cours décrit le fonctionnement du système immunitaire humain et les bases immunologiques de la vaccination, de la transplantation, de l'immunothérapie, et de l'allergie. Il présente aussi le rôle des cellules souches dans la formation des tissus, notamment la lignée hématopoïétique.

This course on water and wastewater treatment shows how to implement and design different methods and techniques to eliminate organic matter, nitrogen and phosporous from wastewater, and how to apply physical and chemical methods and techniques to produce drinking water.

Ce cours permet aux étudiants ayant suivi Morphologie I de réviser et d'approfondir leurs connaissances par l'étude de l'anatomie radiologique et du développement. L'origine de malformations fréquentes est décrite. Divers sujets requis pour l'examen d'entrée à la Passerelle sont aussi traités.

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Patchy Amphiphilic Dendrimers Bind Adenovirus and Control Its Host Interactions and in Vivo Distribution

Weina Liu, Francesco Stellacci

The surface of proteins is heterogeneous with sophisticated but precise hydrophobic and hydrophilic patches, which is essential for their diverse biological functions. To emulate such distinct surface patterns on macromolecules, we used rigid spherical synthetic dendrimers (polyphenylene dendrimers) to provide controlled amphiphilic surface patches with molecular precision. We identified an,. I optimal spatial arrangement of these patches on certain dendrimers that enabled their interaction with human adenovirus 5 (Ads). Patchy dendrimers bound to the surface of Ads formed a synthetic polymer corona that greatly altered various host interactions of Ads as well as in vivo distribution. The dendrimer corona (1) improved the ability of Ad5-derived gene transfer vectors to transduce cells deficient for the primary Ad5 cell membrane receptor and (2) modulated the binding of Ads to blood coagulation factor X, one of the most critical virus host interactions in the bloodstream. It significantly enhanced the transduction efficiency of Ad5 while also protecting it from neutralization by natural antibodies and the complement system in human whole blood. Ads with a synthetic dendrimer corona revealed profoundly altered in vivo distribution, improved transduction of heart, and dampened vector sequestration by liver and spleen. We propose the design of bioactive polymers that bind protein surfaces solely based on their amphiphilic surface patches and protect against a naturally occurring protein corona, which is highly attractive to improve Ad5-based in vivo gene therapy applications.

2019

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Tissue Factor-Independent Coagulation Correlates with Clinical Phenotype in Factor XI Deficiency and Replacement Therapy

Alessandro Aliotta, Vanessa Carle, Christian Heinis

Background In factor XI (FXI) deficiency, bleeding cannot be predicted by routine analyses. Since FXI is involved in tissue factor (TF)-independent propagation loop of coagulation, we hypothesized that investigating the spatiotemporal separated phases of coagulation (TF-dependent and -independent) could improve diagnostics. Objectives This article investigates the correlation of parameters describing TF-dependent and -independent coagulation with the clinical phenotype of FXI deficiency and their ability to assess hemostasis after FXI replacement. Methods We analyzed: (1) plasma from healthy controls ( n =53); (2) normal plasma ( n =4) spiked with increasing concentrations of a specific FXI inhibitor (C7P); (3) plasma from FXI-deficient patients ( n =24) with different clinical phenotypes (13 bleeders, 8 non-bleeders, 3 prothrombotics); (4) FXI-deficient plasma spiked with FXI concentrate ( n =6); and (5) plasma from FXI-deficient patients after FXI replacement ( n =7). Thrombin generation was measured with the reference method calibrated automated thrombogram and with Thrombodynamics (TD), a novel global assay differentiating TF-dependent and -independent coagulation. Results C7P dose-dependently decreased FXI activity, prolonged activated partial thromboplastin time, and hampered TF-independent coagulation. In FXI-deficient bleeders, TD parameters describing TF-independent propagation of coagulation and fibrin clot formation were reduced compared with controls and FXI-deficient nonbleeders and increased in FXI-deficient patients with prothrombotic phenotype. Receiver operating characteristic analysis indicated that TF-independent parameters were useful for discriminating FXI-deficient bleeders from non-bleeders. In FXI-deficient plasma spiked with FXI concentrate and in patients receiving FXI replacement, TD parameters were shifted toward hypercoagulation already at plasma FXI levels around 20%. Conclusion TF-independent coagulation parameters assessed by TD have the potential to identify the clinical phenotype in FXI-deficient patients and to monitor FXI replacement therapy.

GEORG THIEME VERLAG KG2020

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Bioprinting of Cartilaginous Auricular Constructs Utilizing an Enzymatically Crosslinkable Bioink

Nicolas Antoine Vincent Broguiere, Philipp Fisch

Bioprinting of functional tissues could overcome tissue shortages and allow a more rapid response for treatments. However, despite recent progress in bioprinting, and its outstanding ability to position cells and biomaterials in a precise 3D manner, its success has been limited, due to insufficient maturation of constructs into functional tissue. Here, a novel calcium-triggered enzymatic crosslinking (CTEC) mechanism for bioinks based on the activation cascade of Factor XIII is presented and utilized for the biofabrication of cartilaginous constructs. Hyaluronan transglutaminase (HA-TG), an enzymatically crosslinkable material, has shown excellent characteristics for chondrogenesis and builds the basis of the CTEC bioink. The bioink supports tissue maturation with neocartilage formation and stiffening of constructs up to 400 kPa. Bioprinted constructs remain stable in vivo for 24 weeks and bioprinted auricular constructs transform into cartilaginous grafts. A major limitation of the current study is the deposition of collagen I, indicating the maturation toward fibrocartilage rather than elastic cartilage. Shifting the maturation process toward elastic cartilage will therefore be essential in order for the developed bioinks to offer a novel tissue engineered treatment for microtia patients. CTEC bioprinting furthermore opens up use of enzymatically crosslinkable biopolymers and their modularity to support a multitude of tissues.

WILEY-V C H VERLAG GMBH2021

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Tissue Factor-Independent Coagulation Correlates with Clinical Phenotype in Factor XI Deficiency and Replacement Therapy

Alessandro Aliotta, Vanessa Carle, Christian Heinis

GEORG THIEME VERLAG KG2020