Quantificação e caracterização de óleos de canola, carinata e crambe produzidos no Centro-Oeste brasileiro.

As oleaginosas da família Brassicaceae, como canola (Brassica napus), carinata (Brassica carinata) e crambe (Crambe abyssinica), apresentam alto teor de óleo e composições de ácidos graxos que têm atraído o interesse de diferentes segmentos industriais. O cultivo dessas espécies no Cerrado, em safrinha, é uma alternativa para a rotação de culturas e diversificação da matriz produtiva do Brasil na oferta de óleos vegetais. Este trabalho teve como objetivo quantificar e caracterizar os óleos dessas três espécies a partir de grãos produzidos na região de Cerrado, em safrinha. Os materiais de canola Nuola 300, de carinata e de crambe variedade FMS 1 Brilhante foram produzidos em Planaltina, DF, de março a junho, na safra de 2022, e seus teores de óleo foram determinados pelo método de Ankom. Os óleos foram caracterizados quanto ao perfil de ácidos graxos, acidez e estabilidade oxidativa. A canola apresentou 37,4% de óleo, sendo composto majoritariamente de ácido oleico (62,1%); a carinata teve 35,4% de óleo e 42,1% de ácido erúcico; e o crambe apresentou 35,13% de óleo e 56,3% de ácido erúcico. A maior estabilidade oxidativa foi observada no óleo de crambe, que teve 25,5 horas, seguido da carinata, 9,6 horas, e da canola, 8,7 horas. Todos os óleos apresentaram baixa acidez: óleo de canola, 0,6%; óleo de crambe, 0,42%; óleo de carinata, 0,21%

A microengineered vascularized bleeding model that integrates the principal components of hemostasis

Hemostasis encompasses an ensemble of interactions among platelets, coagulation factors, blood cells, endothelium, and hemodynamic forces, but current assays assess only isolated aspects of this complex process. Accordingly, here we develop a comprehensive in vitro mechanical injury bleeding model comprising an “endothelialized” microfluidic system coupled with a microengineered pneumatic valve that induces a vascular “injury”. With perfusion of whole blood, hemostatic plug formation is visualized and “in vitro bleeding time” is measured. We investigate the interaction of different components of hemostasis, gaining insight into several unresolved hematologic issues. Specifically, we visualize and quantitatively demonstrate: the effect of anti-platelet agent on clot contraction and hemostatic plug formation, that von Willebrand factor is essential for hemostasis at high shear, that hemophilia A blood confers unstable hemostatic plug formation and altered fibrin architecture, and the importance of endothelial phosphatidylserine in hemostasis. These results establish the versatility and clinical utility of our microfluidic bleeding model

Microvasculature on a chip: study of the Endothelial Surface Layer and the flow structure of Red Blood Cells

International audienceMicrovasculatures-on-a-chip, i.e. in vitro models that mimic important features of microvessel networks, have gained increasing interest in recent years. Such devices have allowed investigating pathophysiological situations involving abnormal biophysical interactions between blood cells and vessel walls. Still, a central question remains regarding the presence, in such biomimetic systems, of the endothelial glycocalyx. The latter is a glycosaminoglycans-rich surface layer exposed to blood flow, which plays a crucial role in regulating the interactions between circulating cells and the endothelium. Here, we use confocal microscopy to characterize the layer expressed by endothelial cells cultured in microfluidic channels. We show that, under our culture conditions, endothelial cells form a confluent layer on all the walls of the circuit and display a glycocalyx that fully lines the lumen of the microchannels. Moreover, the thickness of this surface layer is found to be on the order of 600 nm, which compares well with measurements performed ex or in vivo on microcapillaries. Furthermore, we investigate how the presence of endothelial cells in the microchannels affects their hydrodynamic resistance and the near-wall motion of red blood cells. Our study thus provides an important insight into the physiological relevance of in vitro microvasculatures. Interactions between circulating blood components and vessel walls are central to the immune 1,2 and inflamma-tory 3,4 response, and to processes such as angiogenesis 5,6 or hemostasis 7. These interactions result from a complex and highly regulated interplay between specific biomolecular adhesion mechanisms at cell/wall interfaces 1,3,8 , chemoattractant expression 2,9 , mechanical properties of the cells 10,11 , and fluid stresses arising from hemody-namics 10–13. Anomalous interactions between blood cells and the endothelium, i.e. the cellular layer lining the internal lumen of blood vessels, are known to be associated with a number of blood and vascular disorders such as thrombosis, atherosclerosis, diabetes mellitus, or sickle cell anemia 3,14. In vitro studies have proven to be extremely useful in order to unravel the respective roles of mechanical, biochemical and biophysical factors that govern some vascular pathologies 15–18. These studies typically rely on microfluidic tools to create networks of channels that recapitulate the microvasculature properties. Such in vitro investigations present several important advantages for the rational studies of blood dynamics, cell trafficking and microvascular functions: (i) they solve technical and ethical issues encountered when working on animal models 19 , (ii) microchannels are made from transparent materials and facilitate the use of advanced and high-resolution microscopy techniques, and (iii) experiments are performed under tightly controlled fluid composition and flow conditions. However, these advantages often come at the cost of a partial loss of physiological relevance, in particular regarding cell/wall interactions. To overcome this limitation, several works have proposed designs of in vitro microvasculatures that mimic not only the architecture, but also the surface properties of blood microvessels: endothelial cells have been cultured in microcircuits, made of silicone elastomer or hydrogels, in order to form a confluent monolayer on their walls, thus providing perfusable channels bearing a model endothe-lium, while displaying two-or three-dimensional network architectures 20–31. Such in vitro microvasculatures have 1 Univ