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In order to establish signaling mechanisms of platelet dysfunction among patients with acute gastroduodenal ulcer bleeding the assessment of agonist-induced platelet aggregation was performed by means of the spectrophotometric method and inhibitory method at the time of hospitalization of patients and the third day after. It has been shown that on the first day of hospitalization the level of collagen- and ADP- induced platelet aggregation was decreased among patients with acute gastroduodenal ulcer bleeding in comparison with the controlgroup. In cases of medium/high level of platelet aggregation, the reverse aggregation graph was recorded that was associated with the risk of recurrent bleeding. On the third day after hospitalization, the rise of ADP-induced platelet aggregation was found on account of PKA becomes a positive regulator of platelet intracellular signaling system. The assessment of induced platelet aggregation among patients with acute gastroduodenal ulcer bleeding compared with the control group allowed to discover a double decreased platelet aggregation to ADP (p=0.004) and 4.5-times decreased platelet aggregation to collagen (p=0.0001). The characteristics of aggregation graphs to ADP have shown partially inverse and inverse platelet aggregation, that was widely spread among patients with medium/high level of platelet aggregation. The previous issue has been associated with reverse and partially reverse aggregation graphs to collagen. Moreover, the highest rate of recurrent bleeding was found among patients with medium/high level of platelet aggregation to collagen (p=0.02) which was featured by a long latency period. The scrutiny also has revealed the correlation between ADP and collagen-induced platelet aggregation (r=0.28; p=0.01), which indicates that platelet disfunction takes place in the intracellular signaling system. On the first day of hospitalization no effect of PK A inhibitor on ADP-induced platelet aggregation was detected (p=0.71). The examination of effect of PK C inhibitor on ADP-induced platelet aggregation also has revealed no effect (p=0.57). In addition to the level of platelet aggregation inhibitors did not influence the characteristics of aggregation graphs. The comparison of ADP- and collagen-induced platelet aggregation in dynamics (on the first and the third days of hospitalization) has shown 2-times growth of platelet aggregation to ADP (p

The uncontrolled parenchymatic bleeding is still a cause of serious complications in surgery and require new effective hemostatic materials. In recent years, numerous chitosan-based materials have been intensively studied for parenchymatic bleeding control but still require to increased safety and effectiveness. The current research is devoted to new hemostatic materials made of natural polymer (chitosan) developed using electrospinning and microwave-assisted methods. Hemostatic performance, biocompatibility, degradation, and in-vivo effectiveness were studied to assess functional properties of new materials. Chitosan-based agents demonstrated considerable hemostatic performance, moderate biodegradation pace and high biocompatibility in vitro. Using the electrospinning-made chitosan-copolymer significantly improved in vivo biocompatibility and degradation of Chitosan-based agents that provides opportunities for its implementation for visceral bleeding management. Chitosan aerogel could be effectively applied in hemostatic patch development due to high antibacterial activity but it is not recommended for visceral application due to moderate inflammatory effect and slow degradation. Unlabelled Image • Chitosan aerogel and electrospun membrane have considerable hemostatic performance. • Chitosan electrospun membrane demonstrate high pore area and advanced interaction with whole blood. • Chitosan aerogel was associated with moderate inflammatory reaction and revealed slow degradation. • Electrospinning-made Ch-copolymer demonstrated high in vivo biocompatibility and degradation pace. [ABSTRACT FROM AUTHOR]