ptFVa ( Pseudonaja Textilis Venom-Derived Factor Va) Retains Structural Integrity Following Proteolysis by Activated Protein C

Objective: The Australian snake ptFV ( Pseudonaja textilis venom-derived factor V) variant that retains cofactor function despite APC (activated protein C)-dependent proteolysis. Here, we aimed to unravel the mechanistic principles by determining the role of the absent Arg306 cleavage site that is required for the inactivation of Fva (mammalian factor Va). Approach and Results: Our findings show that in contrast to human FVa, APC-catalyzed proteolysis of ptFVa at Arg306 and Lys507 does not abrogate ptFVa cofactor function. Remarkably, the structural integrity of APC-proteolyzed ptFVa is maintained indicating that stable noncovalent interactions prevent A2-domain dissociation. Using Molecular Dynamics simulations, we uncovered key regions located in the A1 and A2 domain that may be at the basis of this remarkable characteristic. Conclusions: Taken together, we report a completely novel role for uniquely adapted regions in ptFVa that prevent A2 domain dissociation. As such, these results challenge our current understanding by which strict regulatory mechanisms control FVa activity.

Ước lượng cự ly truyền dẫn trong mạng LoRa hai chặng dưới ảnh hưởng của nhiễu giữa các thiết bị đầu cuối

Mạng diện rộng công suất thấp truyền cự ly dài LoRaWan (long range wide area networks) được triển khai và phát triển nhanh chóng trong những năm gần đây. Với các ưu điểm nổi bật như giá thành thấp, tiết kiệm năng lượng, độ tin cậy cao, số lượng các thiết bị kết nối đến mạng lớn và phạm vi mạng rộng, LoRaWan đặc biệt phù hợp cho các ứng dụng IoT (Internet-of-things). Bài báo thực hiện ước lượng khoảng cách truyền dẫn lớn nhất và vị trí đặt trạm lặp của mạng LoRa hai chặng. Không giống như các nghiên cứu khác chỉ xét đến suy hao và nhiễu tạp âm khi ước lượng cự ly truyền, bài báo phân tích các loại nhiễu trong mạng LoRa gồm nhiễu giữa các thiết bị trong cùng một vùng SF (Spreading Factor) và giữa các vùng SF khác nhau đều được tính đến khi đánh giá chất lượng hệ thống. Các chỉ tiêu kỹ thuật của mạng gồm tỷ lệ tín hiệu trên nhiễu SNR (Singal-to-Noise Ratio) và SIR (Singal-to-Interference Ratio) được tính toán dùng mô hình kênh Rayleigh có xét đến suy hao truyền dẫn, hiệu ứng che khuất và hiệu ứng đa đường. Dựa vào ngưỡng yêu cầu của các chỉ số này trong quy hoạch mạng LoRa, cự ly truyền tối đa và vị trí trạm lặp được tính toán. Kết quả của bài báo có thể được áp dụng trong quy hoạch và thiết kế mạng LoRa.

Thrombotic events in rare kinds of genetic thrombophilias

Цель исследования: изучить лабораторный фенотип редких мутаций Лейдена [FVL А(1961)A] и гена протромбина [FII А(20210)A] при их клинической реализации в виде тромбозов. Материалы и методы. Проведено многоцентровое проспективное наблюдательное исследование, включающее 80 носителей редких генетических форм тромбофилий: FVL А(1961)A (n = 31), FII А(20210)A (n = 10) и компаунд FII G(20210)A + FVL G(1691)A (n = 39). У всех пациентов исследована резистентность фактора Va к активированному протеину С (APC-R) по нормализованному отношению (НО) и уровень активности протромбина в плазме крови в состоянии физического здоровья и в случае эпизода тромботического события. Результаты. Определена ассоциативная связь развития тромботических событий со снижением НО при оценке APC-R как у гомозиготных носителей мутации Лейден (Ме = 0,35; 95% ДИ = 0,31–0,37 по НО), так и гетерозиготных компаундов (Ме = 0,43; 95% ДИ = 0,42–0,45 по НО). Заключение. Лабораторный мониторинг пациентов с редкими формами генетических тромбофилий позволяет выделить группу высокого тромбогенного риска, нуждающуюся в пролонгированной тромбопрофилактике. Objectives: to study the laboratory phenotype of rare Leiden mutation [FVL A(1961)A] and the prothrombin gene mutation [FII А(20210)A] implementating clinically as thrombosis. Patients / Methods. A multicenter prospective observational study included 80 carriers of rare genetic kinds of thrombophilia: FVL A(1961)A (n = 31), prothrombin FII А(20210)A (n = 10) and the compound FII G(20210)A + FVL G(1691)A (n = 39). All patients were tested for the factor Va resistance to activated protein C (APC-R), normalized ratio (NR), and the plasma prothrombin activity (%) in healthy conditions and in the case of thrombotic event. Results. An associative relation between the development of thrombotic events and a decrease in NR was determined when assessing APC-R, both in homozygous carriers of the Leiden mutation (Me = 0.35; 95% CI = 0.31–0.37 in NR) and heterozygous compounds (Me = 0.43; 95% СI = 0.42–0.45 in NR). Conclusions. Laboratory follow up for patients with rare kinds of genetic thrombophilias allows to identify a group at high thrombogenic risk requiring prolonged thromboprophylaxis.

An engineered factor Va prevents bleeding induced by direct-acting oral anticoagulants by different mechanisms

Control of bleeding with direct-acting oral anticoagulants (DOACs) remains an unmet clinical need. Activated superFactor V (superFVa) is an engineered activated protein C (APC)–resistant FVa variant with enhanced procoagulant activity resulting from an A2/A3 domain disulfide bond and was studied here for control of DOAC-induced bleeding. SuperFVa reversed bleeding induced by FXa inhibitors (rivaroxaban, apixaban), and the FIIa inhibitor dabigatran in BalbC mice. The blocking anti-protein C and APC [(A)PC] antibody SPC-54 also reduced FXa inhibitor induced bleeding similar to superFVa, whereas dabigatran-induced bleeding was not affected. This indicated that sufficient APC was generated to contribute to bleeding in the presence of FXa inhibitors, but not in the presence of dabigatran, suggesting that mechanisms contributing to bleeding differed for FXa and FIIa inhibitors. Despite different mechanisms contributing to bleeding, superFVa effectively reduced bleeding for all DOACs, indicating the versatility of superFVa’s properties that contribute to its universal prohemostatic effects for DOAC associated bleeding. Supported by thrombin generation assays on endothelial cells in normal plasma spiked with DOACs and patient plasma anticoagulated with DOACs, 3 complementary mechanisms were identified by which superFVa achieved DOAC class-independent prohemostatic efficiency. These mechanisms are resistance to inactivation by APC, overcoming the FV activation threshold, and maximizing the efficiency of the prothrombinase complex when the available FXa is increased by FVIIa-based prohemostatics. In summary, it is this versatility of superFVa that delineates it from other prohemostatic agents as a promising class-independent rescue agent in bleeding situations associated with DOACs.

Acquiring and Geo-Visualizing Aviation Carbon Footprint among Urban Agglomerations in China

This paper had two main purposes. One was to estimate annual total aviation CO2 emissions from/among all key urban agglomerations (UAs) in China and its changes patterns from 2007 to 2014. The second one was to visualize the aviation carbon footprints among the UAs by using a chord diagram plot. This study also used Kaya identity to decompose the contribution of potential driving forces behind the aviation CO2 emissions using Kaya identity. Especially, it decomposed factor CO2/gross domestic product (GDP), which is wildly used in Kaya identity analysis, into factor CO2/value-added (VA) and factor VA/GDP. Here, VA represents the tourism value added of the corresponding flights. The main results were: (1) The UAs developed a much bigger and stronger carbon network among themselves. (2) There was also an expanding of the flows to less densely populated or less developed UAs. However, the regional disparity increased significantly. (3) Compared with the driving factor of population, the GDP per capita impacted the emission amount more significantly. Our contribution had two folds. First, it advances current knowledge by fulfilling the research gap between transport emissions and UA relationship. Second, it provides a new approach to visualizing the aviation carbon footprints as well as the relationships among UAs.

APC-RESISTANCE ASSOCIATED WITH FACTOR V LEIDEN GENE MUTATION (GENOTYPE GA): CLINICAL OCCURRENCE IN PREGNANCY

Цель исследования: изучить связь феномена резистентности фактора Vа к активированному протеину С (АПС-резистентность) при носительстве мутации гена FVL (1691) GA с клинической реализацией во время беременности тромботических событий и гестационных осложнений, таких как преэклампсия, задержка развития плода и невынашивание беременности. Материалы и методы. Проведено проспективное клиническое когортное исследование 1100 беременных. Выделено 2 когорты: основная группа – 500 пациенток с генотипом FVL (1691) GA и группа контроля – 600 женщин с генотипом FVL (1691) GG. Результаты. Медиана нормализованного отношения (НО) АПС-резистентности в контрольной группе у беременных с генотипом FVL (1691) GG колебалась в диапазоне 1,0→0,86. У беременных – носителей генотипа FVL (1691) GA этот показатель был достоверно ниже – 0,55→0,48 (р < 0,05). У пациенток при НО > 0,5 течение беременности было благоприятным. Более выраженная АПС-резистентность (НО ≤ 0,49) ассоциировалась с гестационными осложнениями. Заключение. Полученные данные по АПС-резистентности позволяют относить в группу высокого риска по тромботическим и акушерским осложнениям женщин – носительниц мутации фактора V Лейден (1691) не только с генотипом АА, но и с генотипом GA. AПС-резистентность ≤ 0,49 (по показателю НО) при носительстве мутации фактора V Лейден (1691) GA может рассматриваться как прогностический маркер развития гестационных осложнений с наибольшей точностью при сроке 7-8 недель беременности. Aim: to study during pregnancy the relationship between factor Va resistance to activated protein C (APC-resistance) in carriers of FVL gene mutation (1691) GA with clinical realization of thrombotic events and gestational complications such as preeclampsia, fetal growth retardation and miscarriage. Materials and methods. A prospective clinical cohort study of 1100 pregnant women was performed. Two cohorts were identified: main group – 500 patients with FVL genotype (1691) GA and control group – 600 women with FVL genotype (1691) GG. Results. The median of normalized ratio (NR) of APC resistance in the control group with FVL genotype (1691) GG ranged from 1.0→0.86. In pregnant women – the carriers of FVL genotype (1691) GA this parameter was significantly lower – 0.55→0.48 (р < 0.05). In patients with HO > 0.5 the course of pregnancy was favorable. More expressed APS-resistance (НО ≤ 0,49) was associated with gestational complications. Conclusion. The obtained data on APC-resistance allow to classify women – the carriers of Factor V Leiden (1691) mutation, not only with the AA genotype but also with GA genotype as the group of high risk for thrombotic and obstetric complications. APC resistance ≤ 0.49 (according NR) with the carriage of Factor V Leiden mutation (1691) GA can be considered as a prognostic marker for the development of gestational complications with the greatest accuracy at a period of 7-8 weeks of gestation.