To compare property in anti-platelet effects of aspirin (a cyclooxygenase inhibitor), cilostazol (a phosphodiesterase III inhibitor) and ramatroban (a specific thromboxane A2 receptor antagonist), we measured human platelet-rich plasma (PRP) aggregation induced by adenosine diphosphate (ADP), collagen and arachidonic acid, and whole blood (WB) aggregation induced by ADP. The release of P-selectin, transforming growth factor-beta 1, and the formation of thromboxane A2 in response to agonists were also investigated. Inhibitory effects of 100 micromol/l aspirin, 10 micromol/l cilostazol and 1 micromol/l ramatroban on 5 micromol/l ADP-induced PRP aggregation were similar. However, aspirin strongly inhibited thromboxane A2 formation in response to 5 micromol/l ADP compared with other drugs. Inhibitory effects of 10 micromol/l cilostazol on PRP aggregation and the release of molecules were quite similar in responsiveness induced by the three agonists. Aspirin and cilostazol inhibited platelet aggregation in a concentration-dependent, non-linear fashion, while ramatroban inhibited linearly with increasing concentration. Anti-platelet effects of drugs having different pharmacological mechanisms were demonstrated clearly by measuring PRP aggregation induced by the three agonists, and by measuring WB aggregation that most probably reflects not only platelet-platelet interactions, but also platelet-leukocyte interactions, as well as the release of intraplatelet molecules.
In the production and management of beef and dairy cattle, controlling diarrhea is one of the important concerns. Pathogenic agents of the disease, protozoan parasites including Cryptosporidium spp., are difficult to control, making prevention, diagnoses, and treatment of diarrhea. In the present study, we investigated a farm with a history of calf deaths over a period of 10 years in order to determine the cause of disease and to clarify the detailed distribution of the pathogens. In four examined calves that were reared in calf pens, all were positive with Cryptosporidium and/or Giardia, while the other breeding stock and adult cattle were negative. Molecular analyses revealed that the isolates from calves were C. parvum subtype IIaA15G2R1 as a zoonotic and G. intestinalis assemblage E. Other pathogenic bacteria and diarrhea-causing viruses were not detected. After treating the calf pens with boiling water and milk of lime (Ca[OH]2), oocysts of C. parvum and cysts of G. intestinalis were not found and no additional calves died. This is the first report to describe the mixed infection of both parasites in Japan.
To investigate platelet responsiveness during cold storage of whole blood, we examined platelet aggregation, expression of CD40 ligand (CD40L) on platelets, the plasma levels of soluble form of CD40L (sCD40L) as well as platelet-leukocyte aggregates. Flow cytometry analysis was performed to investigate platelet-leukocyte aggregate formation using antibodies against CD42b and CD45 and platelet activation using antibodies against P-selectin and PAC-1. Blood samples were collected from healthy volunteers, patients with cardiovascular diseases, or both. In the healthy volunteers' blood samples stored at 4 degrees C for 6 h, platelet aggregation in response to 1 micromol/l ADP was enhanced, and released levels of soluble form of P-selectin and thromboxane B2 in response to 1 micromol/l ADP markedly increased. In the samples stored at 4 degrees C for 6 h but not stimulated by any agonists, CD40L expression on the platelets was increased, and plasma levels of sCD40L were also elevated. Under the same condition, the increase in simultaneous expression of CD45 and CD42b was observed. In patients with cardiovascular diseases, the platelet aggregability, coexpression of P-selectin and PAC-1, expression of CD40L on platelets and both CD45-bound and CD42b-bound subsets were all comparable to those of healthy volunteers' samples stored at 4 degrees C for 6 h. Plasma levels of sCD40L in patients were higher than those in healthy volunteers' control. Taken together, storage of whole blood at 4 degrees C for 6 h caused platelet activation comparable to that of patients with cardiovascular diseases, and enhanced platelet activity in such patients may be involved in increased risk for thromboembolic events.
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