Integrative parameter of platelet aggregation in intensive care of COVID-19 patients

Objective. To conduct a comparative analysis of changes in platelet aggregation parameters in COVID-19 patients which are related to anticoagulant therapy and to determine the effectiveness of the integrative parameter of platelet aggregation.Materials and methods. 34 patients with confirmed COVID-19 (group 1) were included into the study. To compare the obtained results, healthy females were included into group 2 (n = 30). The following parameters of aggregation were determined: degree, time, rate and area of aggregation (until its maximum degree).Results. The area of aggregation is the best among all the parameters of platelet aggregation to diagnose COVID-19 in patients according to the Hosmer-Lemeshow test: with an ADP inducer — 0.3 μg/ml (Chi-square = 9.481, p = 0.303); ADP — 1.25 μg/ml (Chi square = 12.577, p = 0.127); ADP — 2.5 μg/ml (Chi-square = 6.226, p = 0.622); adrenaline — 2.5 μM (Chi-square = 7.367, p = 0.498); adrenaline — 5 μM (Chi-square = 6.824, p = 0.556).Conclusion. The area of aggregation is an informative integrative parameter that allows to quantify the degree of aggregation in the treatment of hypercoagulation syndrome in COVID-19 patients.

On the Identifiability of Hierarchical Decision Models

Interpretability is a desirable property for machine learning and decision models, particularly in the context of safety-critical applications. Another most desirable property of the sought model is to be unique or {\em identifiable} in the considered class of models: the fact that the same functional dependency can be represented by a number of syntactically different models adversely affects the model interpretability, and prevents the expert from easily checking their validity. This paper focuses on the Choquet integral (CI) models and their hierarchical extensions (HCI). HCIs aim to support expert decision making, by gradually aggregating preferences based on criteria; they are widely used in multi-criteria decision aiding {and are receiving interest from the} Machine Learning {community}, as they preserve the high readability of CIs while efficiently scaling up w.r.t. the number of criteria. The main contribution is to establish the identifiability property of HCI under mild conditions: two HCIs implementing the same aggregation function on the criteria space necessarily have the same hierarchical structure and aggregation parameters. The identifiability property holds even when the marginal utility functions are learned from the data. This makes the class of HCI models a most appropriate choice in domains where the model interpretability and reliability are of primary concern.

The viscosity and thrombocytic-aggregation disorders in patients, suffering myocardial infarction with the ST segment elevation

Objective. Analysis of changes in viscosity and disorders of the thrombocytes-aggregation process under impact of various tactical, diagnostic and intervention approaches in patients, suffering myocardial infarction with persistent elevation of ST segment in presence of multivascular affection of coronary arteries. Materials and methods. In the investigation four tactical and treatment-diagnostic approaches were used through year of observation. Results. In patients, suffering myocardial infarction and persistent elevation of ST segment the hyperviscosity and hypercoagulation syndromes were revealed, which have manifested in first weeks by compensatory growth of thrombocytes quantity, the blood viscosity, level of fibrinogen and aggregation properties of thrombocytes. Conduction of additional more profound examination of coronary blood circulation and further application of postponed stenting of the infarction-dependent arteries have promoted lesser amplitude of fluctuations of all laboratory indices, than in other tactical and treatment approaches. Conclusion. Standard tactical and treatment-diagnostic principles in management of such category of patients do not permit to improve the state of the viscosity and coagulation-aggregation parameters principally, even while application of double antiaggregation therapy.

Viscose and thrombocytic-aggregation disorders on patients with myocardial infarction with stable elementation of ST segment

Clinical studies indicate a significant role in the pathogenesis of acute myocardial infarction, the functional state of platelet aggregation and blood viscosity, which determine the nature of blood flow in the vessels at the level of macro– and microcirculation. The aim of the study was to analyze changes in viscosity and platelet-aggregation disorders under the influence of different tactical, diagnostic and interventional approaches in patients with myocardial infarction and stable elevation of the ST segment in the presence of multivascular coronary artery disease. The study used 4 tactical and treatment-diagnostic approaches during the year of observation. Patients with myocardial infarction with persistent ST-segment elevation were found to have hyperviscosity and hypercoagulability syndromes, manifested in the first weeks by a compensatory increase in platelet count, blood viscosity, fibrinogen levels, and an increase in platelet aggregation. Carrying out additional in-depth examination of coronary circulation (coherent tomography and intravascular sonography) as the main methods of detailed assessment of atheromatous process and further application of delayed stenting of infarct-independent arteries in group 1, contributed to lower amplitude of fluctuations, due to the systemic step-by-step improvement of arterial blood supply, to optimize the state of viscosity and processes of adhesion / aggregation of platelets. Traditional tactical and medical-diagnostic principles of this category of patients do not allow to fundamentally improve the state of viscosity and coagulation-aggregation parameters, even with the use of dual antiplatelet therapy.

Synthesis and Properties of Alkyl Bis-Guanidinium Acetates Surfactants

Novel surfactants with double hydrophilic groups (cocopropane and tallowpropane bis-guanidinium acetates), were synthesized and tested to evaluate both the basic surfactant properties and the unique application performance. Surface tension, conductivity and contact angle measurements were used to study the self-aggregation behavior in aqueous solution. Aggregation parameters were calculated such as adsorption efficiency and effectiveness (pC20 and CAC/C20), the maximum surface excess concentration (Гmax) and minimum surface area permolecule (Amin). The thermodynamic parameters of aggregation based conductivity measurements revealed that the aggregation process was spontaneous and entropy-driven. Compared to DTAC and CTAC, the alkyl bis-guanidinium acetates showed a higher emulsification capacity with both liquid kerosene and soybean oil. The evaluation of antimicrobial activity showed that the alkyl bisguanidinium acetates exhibited strong antibacterial activity against the tested strains at a concentration of 50 ppm.

A PRELIMINARY STUDY OF THE EFFECT OF ANESTHETIC AGENTS ON THE RHEOLOGICAL PARAMETERS OF GLYCATED ERYTHROCYTES

This paper presents a preliminary study of the effects of the anesthetics propofol, remifentanil, and vecuronium bromide on the rheological properties of glycated erythrocytes in vitro, modeling the glycation by hyperglycemia observed in diabetes. Viscoelastic and aggregation kinetic parameters of erythrocytes were determined using an erythrocyte rheometer and an optical chip aggregometer developed in our laboratory. The results showed significant alterations in the membrane surface viscosity, the elastic modulus, and the erythrocyte deformability index for the different anesthetics studied. Also, the kinetics aggregation parameters showed different types of alterations due to the effect of anesthetics. This preliminary study suggests that the use of these anesthetics in diabetic patients could induce hemorheological alterations that disturb the microcirculation. For this reason, it is recommended to deepen these investigations to prevent complications in surgical procedures.

Viscose and Thrombocytic-Aggrega-Tion Disorders On Patients With Myocardial Infarction With Stable Elementation of ST Segment

Clinical studies indicate a significant role in the pathogenesis of acute myocardial infarction, the functional state of platelet aggregation and blood viscosity, which determine the nature of blood flow in the vessels at the level of macro- and microcirculation. The aim of the study was to analyze changes in viscosity and platelet-aggregation disorders under the influence of different tactical, diagnostic and interventional approaches in patients with myocardial infarction and stable elevation of the ST segment in the presence of multivascular coronary artery disease. Materials and methods. The study used 4 tactical and treatment-diagnostic approaches during the year of observation. Results. Patients with myocardial infarction with persistent ST-segment elevation were found to have hyperviscosity and hypercoagulability syndromes, manifested in the first weeks by a compensatory increase in platelet count, blood viscosity, fibrinogen levels, and an increase in platelet aggregation. Conclusions. Carrying out additional in-depth examination of coronary circulation (coherent tomography and intravascular sonography) as the main methods of detailed assessment of atheromatous process and further application of delayed stenting of infarct-independent arteries in group 1, contributed to lower amplitude of fluctuations, due to the systemic step-by-step improvement of arterial blood supply, to optimize the state of viscosity and processes of adhesion / aggregation of platelets. Traditional tactical and medical-diagnostic principles of this category of patients do not allow to fundamentally improve the state of viscosity and coagulation-aggregation parameters, even with the use of dual antiplatelet therapy.

STUDY OF THE PLASMA COMPONENT OF THE BLOOD AGGREGATION REGULATORY SYSTEM IN SUBJECTS IN THE EXPERIIMENT WITH 120-DAY ISOLATION INSIDE PRESSURIZED MODULE SIRIUS-19

Citrate plasma samples gathered 31 days prior to, on days 37, 63, 120 in and on days 7 and 14 after isolation (project Sirius-19) were analyzed for blood aggregation parameters including fibrinogen (FBG), D-dimer (DD), plasminogen (PG), antithrombin III (АТ3), protein C (PC) and α2-antiplasmin (AP), thrombin time (TT), activated partial thromboplastin time (APTT), and prothrombin time (PT). DD was lowered in all samples gathered during isolation. The complex of isolation factors combined with physical exercise reduced levels of fibrin formation and fibrinolysis. However, after isolation the procoagulent activity showed an increase manifested by elevated DD and reduced APTT. Appears that in the absence of insertion and reentry effects (redistribution of body fluids in microgravity) and high psychophysiological stresses it is the appropriate use of physical countermeasures that ensures plasma efficiency within the blood aggregation control system, and good body tolerance of the spaceflight factors.

Increased Cardiovascular Risk Associated with Chemical Sensitivity to Perfluoro–Octanoic Acid: Role of Impaired Platelet Aggregation

Perfluoro–alkyl substances (PFAS), particularly perfluoro–octanoic acid (PFOA), are persisting environmental chemicals showing bioaccumulation in human tissues. Recently, exposure to PFAS has been associated with increased prevalence of cardiovascular diseases (CVDs). However, a causal role of PFAS in atherosclerosis pathogenesis is under-investigated. Here, we investigated the effect of PFOA exposure on platelets’ function, a key player in atherosclerosis process. PFOA accumulation in platelets was evaluated by liquid chromatography-mass spectrometry. Changes in platelets’ membrane fluidity and activation after dose-dependent exposure to PFOA were evaluated by merocyanine 540 (MC540) and anti P-Selectin immune staining at flow cytometry, respectively. Intracellular calcium trafficking was analyzed with Fluo4M probe, time-lapse live imaging. Platelets’ aggregation state was also evaluated with Multiplate® aggregometry analyzer in 48 male subjects living in a specific area of the Veneto region with high PFAS environmental pollution, and compared with 30 low-exposure control subjects. Platelets’ membrane was the major target of PFOA, whose dose-dependent accumulation was associated in turn with increased membrane fluidity, as expected by a computational model; increased activation at resting condition; and both calcium uptake and aggregation upon activation. Finally, exposed subjects had higher serum and platelets levels of PFOA, together with increased aggregation parameters at Multiplate®, compared with controls. These data help to explain the emerging association between PFAS exposure and CVD.