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Background: Blood coagulation abnormalities play a major role in COVID-19 pathophysiology. However, the specific details of hypercoagulation and anticoagulation treatment require investigation. The aim of this study was to investigate the status of the coagulation system by means of integral and local clotting assays in COVID-19 patients on admission to the hospital and in hospitalized COVID-19 patients receiving heparin thromboprophylaxis. Methods: Thrombodynamics (TD), thromboelastography (TEG), and standard clotting assays were performed in 153 COVID-19 patients observed in a hospital setting. All patients receiving treatment, except extracorporeal membrane oxygenation (ECMO) patients (n = 108), were administered therapeutic doses of low molecular weight heparin (LMWH) depending on body weight. The ECMO patients (n = 15) were administered unfractionated heparin (UFH). Results: On admission, the patients (n = 30) had extreme hypercoagulation by all integral assays: TD showed hypercoagulation in ~75% of patients, while TEG showed hypercoagulation in ~50% of patients. The patients receiving treatment showed a significant heparin response based on TD; 77% of measurements were in the hypocoagulation range, 15% were normal, and 8% remained in hypercoagulation. TEG showed less of a response to heparin: 24% of measurements were in the hypocoagulation range, 59% were normal and 17% remained in hypercoagulation. While hypocoagulation is likely due to heparin treatment, remaining in significant hypercoagulation may indicate insufficient anticoagulation for some patients, which is in agreement with our clinical findings. There were 3 study patients with registered thrombosis episodes, and all were outside the target range for TD parameters typical for effective thromboprophylaxis (1 patient was in weak hypocoagulation, atypical for the LMWH dose used, and 2 patients remained in the hypercoagulation range despite therapeutic LMWH doses). Conclusion: Patients with COVID-19 have severe hypercoagulation, which persists in some patients receiving anticoagulation treatment, while significant hypocoagulation is observed in others. The data suggest critical issues of hemostasis balance in these patients and indicate the potential importance of integral assays in its control. [ABSTRACT FROM AUTHOR]

There are a number of pathological situations in which ammonia levels increase leading to hyperammonemia, which may cause neurological alterations and can lead to coma and death. Currently, there are no efficient treatments allowing rapid and sustained decrease of ammonia levels in these situations. A way to increase ammonia detoxification would be to increase its incorporation in glutamine by glutamine synthetase. The aim of this work was to develop a procedure to encapsulate glutamine synthetase in mouse erythrocytes and to assess whether administration of these erythrocytes containing glutamine synthetase (GS) reduce ammonia levels in hyperammonemic mice. The procedure developed allowed the encapsulation of 3 ± 0.25 IU of GS/mL of erythrocytes with a 70% cell recovery. Most metabolites, including ATP, remained unaltered in glutamine synthetase-loaded erythrocytes (named ammocytes by us) compared with native erythrocytes. The glutamine synthetase-loaded ammocytes injected in mice survived and retained essentially all of their glutamine synthetase activity for at least 48 h in vivo. Injection of these ammocytes into hyperammonemic mice reduced ammonia levels in the blood by about 50%. The results reported indicate that ammocytes are able to keep their integrity, normal energy metabolism, the inserted glutamine synthetase activity, and can be useful to reduce ammonia levels in hyperammonemic situations. Key words: ammonia, ammocytes, erythrocytes, hyperammonemia, glutamine synthetase. Il existe un nombre de situations pathologiques dans lesquelles les niveaux d'ammoniac augmentent, conduisant a une hyperammoniemie qui peut causer des dommages neurologiques et conduire au coma et a la mort. Il n'y a encore aucun traitement efficace qui permette une diminution rapide et soutenue des niveaux d'ammoniac dans ces situations. Un moyen d'augmenter la detoxication de l'ammoniac serait d'augmenter son incorporation dans la glutamine par la glutamine synthase. Le but de ce travail etait de developper une methode d'encapsulation de la glutamine synthase dans des erythrocytes de souris et d'evaluer si l'administration de ces erythrocytes contenant la glutamine synthase reduit les niveaux d'ammoniac chez des souris hyperammoniemiques. Cette methode a permis d' encapsuler 3 ± 0.25 UI GS / mL d' erythrocytes avec un taux de recuperation cellulaire de 70 %. La plupart des metabolites, incluant f ATP, etaient intacts dans les erythrocytes charges de glutamine synthase (que nous avons appele ammocytes), comparativement aux erythrocytes naturels. Les ammocytes charges de glutamine synthase injectes dans les souris survivaient et conservaient essentiellement toute leur activite glutamine synthase pendant au moins 48 h in vivo. L'injection de ces ammocytes dans les souris hyperammoniemiques a reduit les niveaux d'ammoniac du sang d'environ 50 %. Les resultats rapportes indiquent que les ammocytes peuvent conserver leur integrite, un metabolisme energetique normal et l'activite glutamine synthase ajoutee et qu'ils pourraient etre utiles pour diminuer les niveaux d'ammoniac dans des cas d'hyperammoniemie. Mots-cles : ammoniac, ammocytes, erythrocytes, hyperammoniemie, glutamine synthase. [Traduit par la Redaction], Introduction Ammonia is a product of the degradation of proteins and other nitrogenated compounds. However, at high levels, ammonia is neurotoxic, leading to functional disturbances of the central nervous system, [...]

In this work, we present a new method—Thrombodynamics-4D—for the assessment of both plasma and platelet contributions to clotting. Thrombodynamics-4D potentially allows for the determination of plasma or platelet disorders and the effects of various drugs on plasma clotting or on platelet procoagulant function. In this assay, clot formation in platelet-rich plasma or platelet-free plasma supplemented with phospholipids is activated with tissue factor immobilized on a surface. Spatial fibrin clot growth and thrombin concentration dynamics are registered by measuring light scattering of the fibrin clot and fluorescence of the product formed by cleavage of the synthetic fluorogenic substrate by thrombin, respectively. Here, we describe the preanalytical requirements, measurement methodology and calculation principles of assay parameters. Preanalytical and analytical variability and reference ranges of the assay are given. Additionally, we show some clinical examples, which determine the effect of anticoagulants, measure clotting dysfunction in patients with platelet or coagulation disorders and evaluate the effect of surgery. [ABSTRACT FROM AUTHOR]