Activated platelets express CD40L on their plasma membrane and release the soluble fragment sCD40L. The interaction between platelet surface CD40L and endothelial cell CD40 leads to the activation of endothelium contributing to atherothrombosis. Few studies have directly demonstrated an increased expression of platelet CD40L in conditions of in vivo platelet activation in humans, and no data ar...

The intracellular Ca2 concentration of many nonexcitable cells is regulated by calcium store release and store-operated calcium entry (SOCE). In platelets, STIM1 was recently identified as the main calcium sensor expressed in the endoplasmic reticulum. To evaluate the role of the SOC channel moiety, Orai1, in platelet SOCE, we generated mice expressing a mutated, inactive form of Orai1 in blood...

The need for a gamma-emitting radioactive agent that will label platelets in plasma efficiently by a procedure that can be used uniformly in each laboratory is well recognized. A water soluble sodium salt of 2-Mercaptopyridine-A/-oxide (Merc) was evaluated that quantitatively chelated ln at a pH range of 0.7 to 7.4, and allowed greater than 80% incorporation of ln in platelets in plasma. This w...

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm (MPN) which characterized by proliferation of red blood cells, white cells and platelets. PV associated with the JAK2 V617F mutation. The presenting symptom variable. Headache, weakness, fatigue, pruritus, dyspepsia, dizziness, visual disturbances may be seen in patients. Severe complications such as stroke, acute myocardial infarc...

Chronic HIV-1 infection is associated with persistent viremia in most patients, but it remains unclear how free virus may survive the potential hostile effects of plasma. We investigated whether sites might exist on the surfaces of circulating blood cells for protection of infectious HIV-1 particles. Red blood cells (RBC) either from blood of uninfected normal individuals, or from blood obtaine...

By SHIRLEY EBBE,#{176} MARIO BALDINI AND JANET DONOVAN T HE ABILITY of platelets to survive in the circulation appears to be their most labile property. Platelets may function normally in blood coagulation in the presence of damage severe enough to prevent their circulation when transfused to compatible recipients.1 After storage for 2 weeks, platelets still exhibit clot retraction,2 one of the...

Background:The utility and efficacy of novel materials in tissue regeneration and antimicrobial therapy are contingent upon the employment of either blood derivatives rich in platelets or platelet-poor-plasma (PPP). This effect is largely mediated by the increased or decreased concentration of platelets in the plasma. The current study aimed t...

The need for a gamma-emitting radioactive agent that will label platelets in plasma efficiently by a procedure that can be used uniformly in each laboratory is well recognized. A water soluble sodium salt of 2-Mercaptopyridine-N-oxide (Merc) was evaluated that quantitatively chelated 111ln at a pH range of 0.7 to 7.4, and allowed greater than 80% incorporation of 111ln in platelets in plasma. T...

Platelets are formed from megakaryocytes, where they are released into the blood stream via proplatelet extensions into the blood vessel lumen.1 Being the most numerous “white blood cell” and despite lacking a nucleus, they are highly complex cells containing a surface connected canalicular and tubular system, mitochondria, granules, and bioactive mediators. Platelets are well-known for their s...

The release of potassium from platelets is a well-known cause of pseudohyperkalemia in thrombocytosis. In predicting the magnitude of pseudohyperkalemia associated with thrombocytosis, previous investigations considered only the amount of potassium released from platelets during blood clotting, although the increment in serum potassium during blood clotting depends on the quantity of potassium ...