We have previously demonstrated a low-affinity (0.8 µM, non-covalent complex formation between high-molecular-mass kininogen (HK) and plasminogen (Plg) which prevented Plg interaction with glioma and endothelial cells. We have now extended our previous observations by exploring the potential complex formation between Plg and low-molecular-mass kininogen (LK) and between LK and HK with Plg cleaved with human neutrophil elastase (HNE). Plg cleavage by HNE (Plg HNE) yielded kringles 1Ϫ3, kringle 4 and mini-plasminogen. Plg HNE was subjected to SDS/PAGE under non-reducing conditions, followed by western blotting, and incubated with either 125 I-HK or 125 I-LK. Autoradiograms revealed that 125 I-HK bound to miniplasminogen and to kringles 1Ϫ3 but not to kringle 4 and the presence of 10 mM 6-aminohexanoic acid (Ahx) disrupted only the interaction with kringles 1Ϫ3. In contrast, 125 I-LK bound to miniplasminogen but not to kringles 1Ϫ3 or 4 and Ahx had no effect at all. The complex formation of either HK (0.67 µM) or LK (3 µM) with Plg (1.5 µM) did not affect its conversion to plasmin by tissue plasminogen activator (t-PA) (10 U/ml) in the presence of a tissue plasminogen stimulator (0.14 µM). However, the rate of conversion of plasminogen to plasmin by t-PA was affected when platelets were added to the reaction mixture. Since HK (0.83 µM) has been shown to inhibit plasmin-induced platelet aggregation, we investigated whether this inhibitory property is found within the heavy chain shared by HK and LK. We found that LK inhibited plasmin-induced platelet aggregation, but a 4-fold molar excess was required when compared to HK. Compared to plasmin, 3Ϫ5-fold molar excess of miniplasmin is required to induce platelet aggregation, indicating the important role of kringles 1Ϫ3 for plasmin interactions with these cells. These results indicate that HK and LK-mediated inhibition of plasmin-induced platelet aggregation is likely due to complex formation with kringle 5 without interfering with plasmin's active site. We found an additional interaction between HK and kringles 1Ϫ3 enhancing the inhibitory effect, presumably by interfering with plasmin's interaction with platelets. This HK and LK-associated modulation of plasmin-induced platelet aggregation may serve as a template to develop synthetic peptides as novel therapeutic agents to prevent some of the plasmin-associated thrombocytopenia seen during thrombolytic therapy.

Background/Aims: Data from previous reports, addressing the significance of genotype-guided dosing of warfarin in Egyptian patients, are infrequent and controversial. This study is aimed at demonstrating the validity of genetic dosing algorithms in Egyptian patients on warfarin therapy. Methods: A total of 100 Egyptian patients on a stable maintenance daily dose of warfarin were enrolled. The predicted warfarin dose for each patient was calculated using the warfarin dosing table, the Gage and the International Warfarin Pharmacogenetics Consortium (IWPC) clinical algorithms and the Gage and the IWPC genetic algorithms and compared to the actual dose. The accuracy of warfarin dosing algorithms was assessed by using the linear regression analysis. Results: The most accurate model in predicting the ideal dose was the Gage genetic algorithm by R² of 50.4% and the IWPC genetic algorithm by R² of 42.3%, followed by the warfarin dosing table by R² of 19.1%, and the Gage clinical algorithm by R² of 18.9% and the least accurate was the IWPC clinical algorithm by R² of 9.4%. Conclusions: The Gage ­genetic warfarin dosing algorithm is the best model that could be implemented in Egyptian patients starting warfarin therapy.

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Background:  Several studies reported the role platelet activation, platelet volume (MPV) and other  Indices in breast cancer but the data is inconsistent and/or diverse. The aim of this study was to systematically evaluate the role of platelet activation and platelet volume indices in women with BC as predictors for cancer progression and poor prognosis. Methods: Patients were recruited from our local oncology center between 2019 to 2020 following ethics approval. 80 patients with locally invasive BC, 20 metastatic and 100 controls were recruited. ADP-induced platelet activation was assessed by light-transmission aggregometry. Platelet P-selectin (CD62P) expression with and without ADP stimulation was assessed by flow cytometry. A comprehensive analysis of platelet count and platelet volume indices (PVIs) (MPV, PDW, MPV/P and PDW/P) was conducted. Data were analyzed in relation to tumor pathology, hormone receptors (ER, PR, HER-2) and proliferation index Ki-67. Regression analyses were conducted for the prediction of poor prognosis, tumor aggression and metastatic potential. Results: We found a significant increase in platelet aggregation (MA), CD62P expression, CD62P+ADP, MPV, PDW, MPV/P and PDW/P in the metastatic group compared to the locally invasive group.  Univariate regression analysis showed significance for  ADP, MA,  CD62P+ADP,   MPV   and   PDW/P.  Conclusion: MPV/P and PDW/P can be used as simple low-cost predictors for cancer progression and poor prognosis. We conclude platelet activation and specific platelet indices can help predict prognosis in females with BC.

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