Púrpura fulminante posvaricelosa: potencialmente mortal / Post-varicella purpura fulminans: Potentially fatal

Aunque la varicela suele ser una enfermedad benigna, algunas complicaciones pueden ser mortales, como la púrpura fulminante posvaricelosa. Su mecanismo fisiopatogénico se explica por la producción de anticuerpos para las proteínas C y S de la cascada de la coagulación, lo que puede tener consecuencias funestas con la producción de coagulopatía de consumo en personas con déficits parciales de estas proteínas. El tratamiento es sintomático y consiste básicamente en la administración de plasma fresco congelado (para suplir las proteínas que se consumen), de antitrombina III y heparinización (para tratar la producción de trombos) y de antiinflamatorios, como los corticoides; sin embargo, se están introduciendo tratamientos nuevos, como la prostaglandina E1 intravenosa y la prostaciclina (AU)

Although varicella is usually a benign disease, some of its complications, such as post-varicella purpura fulminans, can be fatal. Its pathophysiological mechanism is caused by the production of antibodies to protein C and protein S in the coagulation cascade. This could have fatal consequences for those patients with partial deficiency of these proteins that develop disseminated intravascular coagulation. Treatment is symptomatic: fresh frozen plasma to treat protein depletion, antithrombin III and heparinization against thrombus formation, and anti-inflammatory drugs (steroids). However, new therapies, such as prostaglandin E1 IV and prostacyclin, are being introduced (AU)

Syk expression in endothelial cells and their morphologic defects in embryonic Syk-deficient mice.

Mice deficient in the Syk tyrosine kinase showed severe petechiae in utero and died shortly after birth. The mechanism of this bleeding, however, remains unknown. Here it is shown that this bleeding is caused by morphologic defects of Syk-deficient endothelial cells during embryogenesis. Immunoblot and reverse transcriptase-polymerase chain reaction Northern blot analysis indicated that Syk is expressed in several endothelial cell lines. Immunocytochemical analysis also confirmed that Syk is expressed in the normal embryonic endothelial cells and is absent in Syk-deficient mice. Furthermore, electron microscopic analysis of Syk-deficient mice revealed an abnormal morphogenesis and a decreased number of endothelial cells. The results indicate a critical role for Syk in endothelial cell function and in maintaining vascular integrity in vivo.

Perinatal lethality and blocked B-cell development in mice lacking the tyrosine kinase Syk.

The tyrosine kinase Syk (relative molecular mass 72,000), which is widely expressed in haematopoietic cells, becomes associated with and activated by engagement of the B-cell antigen receptor. Furthermore, it has been implicated in signalling through the receptors for interleukin-2 (IL-2), granulocyte colony-stimulating factor (G-CSF) and Fc, the T cell receptor, as well as through receptors for several platelet agonists. A homologous kinase, ZAP-70, is crucial in signalling through the T-cell receptor and in T-cell development. Using homologous recombination in embryonic stem cells, we created mice null for the syk gene which showed petechiae in utero and died shortly after birth. Irradiated mice reconstituted with Syk-deficient fetal liver showed a block in B-cell development at the pro-B to pre-B cell transition, consistent with a key role for Syk in pre-B-cell receptor signalling. Despite the production of small numbers of immature B cells, Syk-deficient radiation chimaeras failed to accumulate mature B cells, indicating a possible role for this protein in the production or maintenance of mature B cells. In addition, whereas the development of alpha beta T cells proceeded normally, Syk-deficient mice showed impaired development of thymocytes using the V gamma 3 variable region gene (V gamma 3+ thymocytes). Finally, we show that Syk is not required for signalling through the IL-2 and G-CSF receptors.