Membrane-derived microvesicles: important and underappreciated mediators of cell-to-cell communication.

Normal and malignant cells shed from their surface membranes as well as secrete from the endosomal membrane compartment circular membrane fragments called microvesicles (MV). MV that are released from viable cells are usually smaller in size compared to the apoptotic bodies derived from damaged cells and unlike them do not contain fragmented DNA. Growing experimental evidence indicates that MV are an underappreciated component of the cell environment and play an important pleiotropic role in many biological processes. Generally, MV are enriched in various bioactive molecules and may (i) directly stimulate cells as a kind of 'signaling complex', (ii) transfer membrane receptors, proteins, mRNA and organelles (e.g., mitochondria) between cells and finally (iii) deliver infectious agents into cells (e.g., human immuno deficiency virus, prions). In this review, we discuss the pleiotropic effects of MV that are important for communication between cells, as well as the role of MV in carcinogenesis, coagulation, immune responses and modulation of susceptibility/infectability of cells to retroviruses or prions.

High fever (greater than 39 degrees C) as a clinical manifestation of pulmonary embolism.

This is a review of seven patients with pulmonary emboli manifested as high fever (temperature greater than 39 degrees C) seen over a 3 year period by an infectious disease consultant for unexplained fever. The patients' ages ranged from 16 to 81 years. Bed confinement was the underlying condition of all but one patient. Fever resolved with intravenous heparin therapy in three patients and one patient recovered without heparin therapy. Three patients died. Regardless of the degree of fever, pulmonary emboli should be among the list of differential diagnoses in patients with unexplained fever, especially in those who are confined to bed.