Leucocyte

Conclusions: Peripheral blood leucocyte ratios are useful infection biomarkers, with the most evidence related to diagnosis of bacteraemia and influenza virus infection. In critical illness due to sepsis, a signal towards an association with NLR and outcomes exists, and NLR should be evaluated in future stratification models. Longitudinal measurement of ratios during infection could be informative. Overall, these biomarkers warrant further recognition and study in infectious diseases.

leucocyte

The selectins are transmembrane, Ca(2+)-dependent lectins that mediate leucocyte rolling on vascular surfaces, the first adhesive step during inflammation and immune surveillance. Leucocytes express L-selectin, activated platelets express P-selectin, and activated endothelial cells express E- and P-selectin. Rolling involves force-regulated, rapidly reversible interactions of selectins with a limited number of glycosylated cell surface ligands. Rolling permits leucocytes to interact with immobilized chemokines that convert β2 integrins to high-affinity conformations, which mediate arrest, post-arrest adhesion strengthening, and transendothelial migration. However, rolling leucocytes also transduce signals through selectin ligands, the focus of this review. These signals include serial activation of kinases and recruitment of adaptors that convert integrins to intermediate-affinity conformations, which decrease rolling velocities. In vitro, selectin signalling enables myeloid cells to respond to suboptimal levels of chemokines and other agonists. This cooperative signalling triggers effector responses such as degranulation, superoxide production, chemokine synthesis, and release of procoagulant/proinflammatory microparticles. In vivo, selectin-mediated adhesion and signalling likely contributes to atherosclerosis, arterial and deep vein thrombosis, ischaemia-reperfusion injury, and other cardiovascular diseases.

The topical use of platelet concentrates is recent and its efficiency remains controversial. Several techniques for platelet concentrates are available; however, their applications have been confusing because each method leads to a different product with different biology and potential uses. Here, we present classification of the different platelet concentrates into four categories, depending on their leucocyte and fibrin content: pure platelet-rich plasma (P-PRP), such as cell separator PRP, Vivostat PRF or Anitua's PRGF; leucocyte- and platelet-rich plasma (L-PRP), such as Curasan, Regen, Plateltex, SmartPReP, PCCS, Magellan or GPS PRP; pure plaletet-rich fibrin (P-PRF), such as Fibrinet; and leucocyte- and platelet-rich fibrin (L-PRF), such as Choukroun's PRF. This classification should help to elucidate successes and failures that have occurred so far, as well as providing an objective approach for the further development of these techniques.

White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multipotent cells in the bone marrow known as hematopoietic stem cells.[1] Leukocytes are found throughout the body, including the blood and lymphatic system.[2]

Some leucocytes migrate into the tissues of the body to take up a permanent residence at that location rather than remaining in the blood. Often these cells have specific names depending upon which tissue they settle in, such as fixed macrophages in the liver, which become known as Kupffer cells. These cells still serve a role in the immune system.

THE many pathophysiological effects produced by endotoxins are subject to considerable variation. Such variation may serve as a useful tool for analysing the mechisms of endotoxin activity, if different strains of highly inbred animals raised in the same environmental conditions can be found to differ in their responses to the same materials. Previous observations have indicated that this might be so with regard to the intraperitoneal leucocyte response to endotoxin in mice1. The investigation reported here was initiated to determine the extent of the intraspecies variation in this type of cellular response and eventually the degree of genetic control involved.

Microcirculatory, leucocyte/endothelium interaction and survival time effects of dobutamine in the dose of 5 μg/kg/minute associated or not with volume resuscitation were studied in the hamster window chamber model during resuscitation from nonhypotensive endotoxemia [1, 2].

Dobuta had lower arteriolar diameter than Control (51 10 and 114 10% from baseline). LPS and Dobuta had lower FCD than Control and baseline values (18 15; 16 18; and 88 6% from baseline, in LPS, Dobuta and Control, respectively). VR and VR/Dobuta restored FCD from baseline (382 19 and 476 30% from baseline in VR and VR/Dobuta, respectively). FCD in VR and VR/Dobuta were lower than Control. LPS and Dobuta had higher leucocytes adhesion than Control (42.2 10; 32.2 31; and 4.0 7.1 leucocytes/mm2 in LPS, Dobuta and Control groups, respectively). There was no significant difference in survival time between VR and Control, and VR/Dobuta and Control. Survival time was significantly lower in LPS and Dobuta than Control.

Dobutamine associated or not with volume resuscitation did not improve microcirculatory parameters, leucocyte adhesion or survival time during resuscitation from nonhypotensive endotoxemia while volume resuscitation restored microcirculatory parameters and improved survival time.

In addition to the mandatory and other tests required for blood donations described in Chapter 9, and leucocyte counting (see sections 6.3 and 7.1), a minimum of 75% of those components tested for the parameters shown in Table 7.7 shall meet the specified values.

Les leucocytes constituent les éléments cellulaires sanguins les moins nombreux, après les érythrocytes et les plaquettes. Ils sont caractérisés par une taille en général plus grande, et par la présence d'un noyau. Leur durée de vie dans le sang est de quelques jours en moyenne.

Les leucocytes, aussi appelés globules blancs, sont des cellules produites par notre moelle osseuse. Elles ont une importance capitale dans le bon fonctionnement de nos défenses naturelles. 041b061a72