Activated Blood Coagulation Factor Research Articles

Hemostasis disorders in patients with systemic AL-amyloidosis

To analyze the frequency and nature of hemorrhagic and thrombotic complications in patients with systemic AL-amyloidosis and compare with laboratory changes in the hemostasis system. The prospective study included 40 patients with newly diagnosed AL-amyloidosis. To detect amyloid, all patients underwent bone marrow trephine biopsy and duodenal biopsy, and 28 (70%) patients underwent biopsy of the affected organ. Before the start of therapy, all patients were determined the platelet count, activated partial thromboplastin time, thrombin time, fibrinogen concentration, time of XIIa-dependent fibrinolysis, antithrombin III, D-dimer, activity of blood coagulation factors VIII, X and vWF. The statistical part of the study was carried out using the IBM SPSS Statistics 2017 system software (SPSS, Chicago, IL, USA). In 20 (50%) patients, hemorrhages on the skin and mucous membranes were diagnosed as vascular purpura. Before the start of therapy, 7 (17.5%) patients had thrombosis, including leg vein thrombosis (5 patients), ischemic stroke (2 patients). There was a direct correlation between thrombotic complications and cutaneous hemorrhagic syndrome (p=0.007). In 15 (75%) cases, cutaneous hemorrhagic syndrome was accompanied by hypercoagulable shifts in the hemostasis system. Of the 20 patients with cutaneous hemorrhagic syndrome, 19 (95%) patients had kidney damage, including 15 patients with nephrotic syndrome. Hematoma type of bleeding, as well as heavy bleeding was not observed, including after a biopsy of the internal organs. According to the totality of hemostasis indicators, hypercoagulation syndrome was more often observed (in 23; 56% of patients). Hypocoagulation was diagnosed only in 2 (5%) patients with liver damage, 16 (39%) patients had normocoagulation. Cutaneous hemorrhagic syndrome is the most common clinical manifestation of disorders in the hemostasis system in patients with AL-amyloidosis. The relationship of hemorrhages on the skin with nephrotic syndrome has been established, which may indicate a single pathogenetic mechanism. Cutaneous hemorrhagic syndrome is associated with hypercoagulable shifts in hemostasis and a high risk of thrombotic complications.

Characteristics of FXa-storing platelets in hemophilia B mice and the influence of alcohol on the platelets

Platelet-stored activated blood coagulation factor X (FXa) has great potential in the gene therapy of hemophilia B (HB). However, we still need to understand more about the properties of FXa-storing platelets and how dietary factors affect them. We created transgenic mice called 2bFXa-HB, which had stable expression and storage of FXa in their platelets, resulting in the alleviation of the bleeding disorder in these mice. Even after inducing anti-factor IX (FIX) inhibitors in 2bFXa-HB mice, the hemorrhage phenotype could still be rescued by the expression of FXa. The activation capacity of 2bFXa-HB platelets remained unchanged, and there were no signs of elevated thrombotic risk in these mice. In an acute alcohol exposure mouse model, a single administration of alcohol reduced both the number of platelets and their activation capacity, as well as impaired coagulation function. However, it did not increase the markers of thrombotic risk in either 2bFXa-HB or HB mice. These results suggest that FXa storage in platelets is safe and effective for treatment of HB, but alcohol could impair the therapeutic effect of FXa-containing platelets.

Perioperative coagulation activation after permanent pacemaker placement.

Bradyarrhythmias are typically treated with permanent pacemakers (PM). The elimination of bradyarrhythmia by PM implantation improves the patient's quality of life and prognosis, but it can also result in a number of sequalae. It is still unclear how PM implantation affects the hemostasis system's parameters and how such parameters relate to different consequences after PM placement. To assess the blood coagulation factor activity in PM patients throughout the perioperative period. Patients treated in the Department of Surgical Therapy of Cardiac Arrhythmias and Pacing at the Ryazan State "Regional Clinical Cardiology Dispensary" from April 2020 to December 2021 were included in the study. Before surgery, 7 and 30 d after PM placement, peripheral venous blood samples were withdrawn to measure the level of blood coagulation factor I (FI) and the activity of blood coagulation factors II (FII), V (FV), VII (FVII), VIII (FVIII), IX (FIX), X (FX), XI (FXI), XII (FXII). We used an automatic coagulometer Sysmex CA 660 (Sysmex Europe, Germany) and reagents from Siemens (Siemens Healthcare Diagnostics Products GmbH, Germany). The study included 146 patients. The activity of factors FV [147.7 (102.1-247.55)% vs 103.85 (60-161.6)% vs 81.8 (67.15-130.65)%, P = 0.002], FVIII [80.4 (60.15-106.25)% vs 70.3 (48.5-89.1)% vs 63.7 (41.6-88.25)%, P = 0.039], FIX [86.2 (70.75-102.95)% vs 75.4 (59.2-88.3)% vs 73.9 (56.45-93.05)%, P = 0.014], FX [188.9 (99.3-308.18)% vs 158.9 (83.3-230)% vs 127.2 (95.25-209.35)%, P = 0.022], FXI [82.6 (63.9-103.6)% vs 69.75 (53.8-97.6)% vs 67.3 (54.25-98.05)%, P = 0.002], FXII [87.6 (67.15-102.3)% vs 78.9 (63.4-97.05)% vs 81.2 (62.15-97.4)%, P < 0.001] decreased at 7 and 30 d after surgery; FII activity [157.9 (109.7-245.25)% vs 130 (86.8-192.5)% vs 144.8 (103.31-185.6)%, P = 0.021] decreased at 7 d and increased at 30 d postoperatively. There were no statistically significant changes in the FVII activity within 30 d after PM placement [182.2 (85.1-344.8)% vs 157.2 (99.1-259)% vs 108.9 (74.9-219.8)%, P = 0.128]. Subgroup analysis revealed similar changes only in patients on anticoagulant therapy. FXII activity decreased in patients on antiplatelet therapy [82 (65.8-101.9)% vs 79.9 (63.3-97.1)% vs 89.7 (75.7-102.5)%, P = 0.01] 7 d after surgery, returning to baseline values at 30 d postoperatively. PM placement and anticoagulant therapy were associated with decreased activity of clotting factors FV, FVIII, FIX, FX, FXI, FXII in the postoperative period. FVII activity did not decrease within 30 d after PM placement, which may indicate endothelial injury caused by lead placement.

Venous Thrombosis Due to Duplication of the Inferior Vena Cava with Decreased Protein C Activity: A Case Report

Introduction: Duplication of the inferior vena cava (IVC) is a congenital venous malformation that occurs in 0.2%-3% of the population as a result of persistent left and right supracardinal veins. The IVC duplication is prone to deep vein thrombosis due to endothelial dysfunction and associated venous stasis. This is a rare case of recurrent venous thrombosis due to IVC duplication and decreased protein C activity. Case: A 57-year-old male presented with swelling of the left lower limb that gradually developed over a one-week period preceding his visit. He reported a history of superior mesenteric vein thrombosis, approximately three years ago, for which he received anticoagulation therapy for three months. Thoracoabdominal contrast-enhanced computed tomography (CT) revealed thrombi in the locations of the bilateral main pulmonary arteries, IVC duplication, left common iliac vein, left IVC, and left renal vein. Blood work confirmed protein C activity of 21% (baseline 64%-146%), that could have contributed to the recurrent IVC thrombosis and formation of pulmonary artery thrombus. Subsequently, the patient was hospitalized and started on anticoagulation therapy. The swelling in the left lower extremity gradually improved, and the patient was instructed to continue anticoagulation therapy permanently. Conclusion: When investigating venous thrombosis of unknown or recurrent origin, it is necessary to include venous malformations and abnormal activity of blood coagulation factors in differential diagnosis.

Effect of allogeneic blood transfusion on neutrophil functional activity and lymphocyte cytotoxicity in recipient rabbits

The relevance of this paper is that transfusion of allogeneic blood to recipient animals is always associated with immunological risks. In this regard, the purpose of this study was to assess the state of phagocytic activity of blood neutrophils by indicators of phagocytic index, phagocytic number, and oxygen-dependent bactericidal activity, as well as to establish changes in antibody-dependent cytotoxic activity of lymphocytes in recipient rabbits during allogeneic whole blood transfusion. Modelling of blood transfusions was performed on five clinically healthy rabbits by intravenous administration of whole blood at the rate of 5.5 ml/kg of body weight. Blood samples were taken from animals on Days 3, 7, and 23 after blood transfusion. Neutrophil populations were obtained from blood samples by centrifugation on a double density gradient of 1.077 and 1.093 Ficoll-Verografin. The absorption activity of phagocytes was determined in a microscopic test. To investigate the oxygen-dependent bactericidal activity of neutrophils, a spontaneous test with nitroblue tetrazolium was performed. Antibody-dependent cytotoxic activity of lymphocytes was investigated by colorimetric method. It was found that after the transfusion of whole blood, the phagocytic activity of neutrophils increases with a simultaneous decrease in their absorption capacity. On Days 3 and 7, the results of the spontaneous test with nitroblue tetrazolium decreased. This indicates inactivation of the oxygen-dependent bactericidal activity of neutrophil granulocytes during the first phase of post-transfusion immunological reactions. On Day 23, there was an increase in the values of the indicators of the spontaneous test with nitroblue tetrazolium, which indicates the activation of the bactericidal properties of phagocytes. It was found that on Day 3, the antibody-dependent cytotoxic activity of lymphocytes significantly decreased relative to the initial state, and on Days 7 and 23, it increased. An increase in the antibody-dependent cytotoxic activity of lymphocytes should be associated with the active synthesis of antibodies of the late phase of the immune response. Consequently, transfusion of allogeneic blood causes an immune response in recipient rabbits, without causing immediate and long-term transfusion reactions (changes in heart rate, respiratory rate, body temperature). The obtained results are of practical value both for scientists and practising doctors who use transfusion of whole blood and its components to animals with acute anaemia, impaired functional activity of blood coagulation factors, parasitic, and oncological diseases

Hemostasis system in patients with bradycardias after the implantation of dual-chamber pacemakers

Introduction: As with many other surgical interventions, the implantation of a pacemaker may be associated with adverse outcomes in the immediate or distant period. The search for probable risk factors of adverse outcomes may promote the development of effective and safe management methods of patients with pacemaker postoperatively. One of the important directions in this field is the investigation of the effect of pacemaker implantation on the hemostasis system of these patients.&#x0D; Aim: To evaluate the effect of the implantation of dual-chamber pacemaker on the hemostasis system of patients with different kinds of bradyarrhythmias and to determine probable risk factors for unfavorable outcomes in this groupof patients.&#x0D; Materials and methods: The study was performed with the financial support of the Russian Foundation for Basic Research within the Scientific Project No. 19-315-90109. The prospective study (ClinicalTrials.gov ID, NCT04499612) enrolled 61 patients (men, 45.9%) with a mean age of 71.5 8.8 years. The groupwho received surgical treatment included 23 patients with atrioventricular (AV) block and 25 patients with sick sinus syndrome (SSS), and the groupwith conservative treatment included 13 patients with AV blocks and SSS, but without indications for pacemaker implantation. Anticoagulant therapy was given to one patient with AV block, 12 patients with SSS, and five patients with conservative therapy. All the remaining patients received antiplatelet therapy. The surgical groupunderwent ultrasound examination of the veins of the upper and lower extremities and sampling of peripheral venous blood before and 7 days after pacemaker implantation to determine the level of fibrinogen (FI) and activity of blood coagulation factors VIII (FVIII) and IX (FIX), antithrombin III (AT III), and protein C. In the conservative group, a similar examination was conducted only on inclusion in the study.&#x0D; Results: In patients with AV block, a significant increase in blood fibrinogen was noted at 7 days after surgery (р=0.042). In the intergroupcomparison, the activity of AT III after the implantation was higher in the surgical groupthan in the conservative group(р=0.018 and р=0.006, respectively). After surgery, the activity of FVIII and FIX was lower in patients with SSS on anticoagulant therapy than in patients with antiplatelet therapy (р=0.048 and р=0.015, respectively). Based on the receiver operating characteristics analysis, the risk factors for lethal outcomes were reduced activity of AT III in patients with AV block and increased activity of FIX in patients with SSS.&#x0D; Conclusions: The balance of the hemostasis system in patients with AV blocks on antiplatelet therapy was shifted toward hypercoagulation within at least 7 days after pacemaker implantation. The use of anticoagulants in patients with SSS caused a shift toward hypocoagulation. The reduced activity of AT III in patients with AV block and increased activity of FIX in patients with SSS are prognostic factors for lethal outcomes.

Structural insights into the activation of blood coagulation factor XI zymogen by thrombin: A computational molecular dynamics study

Activation of human blood coagulation factor XI zymogen to factor XIa plays a significant role in the upstream coagulation pathway, in which factor XIa activates factor IX zymogen. The mechanistic details of the proteolytic activation of factor XI by the activating enzyme thrombin are not well-understood at atomic level. In this study, we employed a combination of molecular docking and microsecond time-scale molecular dynamics simulations to identify the key regions of interaction between fXI and thrombin. The activating complex between the substrate and enzyme was modeled to represent the initial acylation step of the serine-protease hydrolysis mechanism. The proposed solution structural complex, fIX:fIIa, obtained from 3 microseconds of MD refinement, suggests that the activation of factor XI is mediated by thrombin's anion binding exosite-II interactions with A3 and A4 domains. We predict that the two positively charged arginine residues (Arg409 and Arg413) in the exosite-2 region, the β- and γ-insertion loops of thrombin play an important structural role in the initial activating complex between fXI and thrombin.

Age-dependent possible role of contact-activated blood coagulation factor XII as a potential contributor to the “bradykinin storm” in COVID-19 patients

Bradykinin was implicated in a new complex model of pathomechanism leading to the symptoms of COVID-19 created by a computer-assisted association analysis. According to this model, the decrease in angiotensin-converting enzyme expression leads to impaired bradykinin elimination and subsequent enrichment in the lungs. However, there is no mentioning of the importance of blood coagulation factor XII in increased bradykinin production, in spite of its age-dependent activation and the lower level of C1-esterase inhibitor (C1INH). Activated factor XII may be an important contributor to the "bradykinin storm" in elder cardiovascular patients. Literature review. 1) Activation of the coagulation factor XII on the surface of SARS-CoV-2 infected endothelial cells may trigger the prekallikrein/kallikrein/kinin system producing bradykinin. Such process is taking place in hantavirus infections causing severe lung and kidney damages. 2) The endothelial system is dysregulated in elderly patients, resulting in potentially higher factor XII activities on the surface of damaged endothelial cells in the stiffened arteries. This can contribute to the higher mortality rates in the elderly. The targeted inhibition of activated blood coagulation factor XII may represent a new therapeutic target for COVID-19, especially for elder patients. Recently, beneficial results have already been observed by the clinical applications of recombinant C1INH and bradykinin receptor antagonists. Orv Hetil. 2020; 161(50): 2099-2103.

Pathogenetically differentiated management of pregnancy in patients with retrochorial hematoma

Introduction. Intrauterine hematomas commonly found in routine ultrasound examinations represent one of causes resulting in early pregnancy loss. The most common is retrochorial hematoma resulting from fetal egg detachment from the uterine wall. Retrochorial hematoma often leads to pregnancy complications and affects gestational process. Aim: to develop a personalized approach to the diagnosis, prevention and management of pregnancy with retrochorial hematomas in the early stages. Materials and methods. A prospective examination of 70 females, aged 22 to 37 years old, with retrochorial hematoma was performed at gestational age ranging from 5 to 12 weeks. Here, we examined serum level for lupus anticoagulant, antiphospholipid antibodies (AFA), antibodies to cardiolipin, fi2-glycoprotein I, to annexin V and prothrombin, and ADAMTS-13. All women were examined for genetic mutations linked to high thrombogenic risk and low thrombogenic risk polymorphisms. Patients were also examined for urinary tract infections. Results. It was found that 43 (61 %) females had aggravated obstetric anamnesis (non-developing pregnancy, spontaneous miscarriage in early stages, antenatal fetal death), whereas 13 (18.5 %) subjects had burdened familial thrombotic history (heart attack, stroke, and thrombosis occurred before the age of 55 years in first-line relatives). In addition, 22 (31.4 %) females were found to have genetic and acquired forms of thrombophilia; 6 (8.5 %) were detected to have circulatory ADAMTS-13 inhibitor; 5 females were confirmed to have decreased blood coagulation factor activity; and 38 (54.2 %) had vaginal dysbiosis. Conclusion. Our work demonstrates that a personified and pathogenetically differentiated algorithm for diagnostics and management of pregnant women with chorionic detachments in early stages allows to lower frequency of early abortions and increases the therapeutic effectiveness.

Фармакокинетика и фармакогенетика эдоксабана

Edoxaban is a new generation of oral anticoagulant; it is selective, direct and reversible inhibitor of activated blood coagulation factor X (F Xa), serine protease responsible for thrombin formation. Edoxaban is used to prevent stroke in non-valvular atrial fibrillation, to treat deep vein thrombosis and pulmonary embolism. The purpose of the review is to analyze the associative studies of OHB of CYP3A4 / 5 and ABCB1 genes, as well as to search for new candidate genes reflecting the efficacy and safety of edoxaban. The search for full-text publications in Russian and English over the past two decades was carried out in eLibrary, PubMed, Web of Science, OMIM databases using the following keywords: edoxaban, pharmacokinetics, pharmacogenetics, efficacy, and safety. The review covers pharmacokinetics of edoxaban, as well as pharmacogenetic features of the drug metabolism in details. Candidate genes influencing concentration of edoxaban are genes encoding key enzymes of its metabolism – CES1, CYP3A4 / 5, ABCB1, and, to a lesser extent, SLCO1B1. By present day, numerous NVS of candidate genes have been identified. They potentially affect pharmacokinetics of edoxaban, but their role in real clinical practice requires further study

Edoxaban Exerts Antioxidant Effects Through FXa Inhibition and Direct Radical-Scavenging Activity.

The interplay between oxidative stress, inflammation, and tissue fibrosis leads to the progression of chronic kidney disease (CKD). Edoxaban, an activated blood coagulation factor Xa (FXa) inhibitor, ameliorates kidney disease by suppressing inflammation and tissue fibrosis in animal models. Interestingly, rivaroxaban, another FXa inhibitor, suppresses oxidative stress induced by FXa. Thus, FXa inhibitors could be multitargeted drugs for the three aforementioned risk factors for the progression of CKD. However, the exact mechanism responsible for eliciting the antioxidant effect of FXa inhibitors remains unclear. In this study, the antioxidant effect of edoxaban was evaluated. First, the intracellular antioxidant properties of edoxaban were evaluated using human proximal tubular cells (HK-2 cells). Next, direct radical scavenging activity was measured using the electron spin resonance and fluorescence analysis methods. Results show that edoxaban exhibited antioxidant effects on oxidative stress induced by FXa, indoxyl sulfate, and angiotensin II in HK-2 cells, as well as the FXa inhibitory activity, was involved in part of the antioxidant mechanism. Moreover, edoxaban exerted its antioxidative effect through its structure-specific direct radical scavenging activity. Edoxaban exerts antioxidant effects by inhibiting FXa and through direct radical-scavenging activity, and thus, may serve as multitargeted drugs for the three primary risk factors associated with progression of CKD.

An Inhibitor of Activated Blood Coagulation Factor X Shows Anti-Endothelial Senescence and Anti-Atherosclerotic Effects

Background: Coagulant factor Xa inhibitors (XaIs) are prescribed for patients with atrial fibrillation for years. Methods: Human umbilical venous endothelial cells (HUVECs) were cultured with or without (w/wo) a XaI (rivaroxaban) under high glucose (HG: 22 mM). Endothelial senescence was investigated by assessing senescence-associated-β-galactosidase (SA-β-gal), p53, and telomere length. Endothelial function and atherosclerosis were examined by nitric oxide-related-products (NOx: NO₂^– and NO₃^–), O₂^–, endothelial NO synthase (eNOS), NADPH oxidase (p22^phox), and ICAM1. PAR1 (protease-activated receptor 1) and PAR2, which were reported to regulate eNOS phosphorylation, were inhibited by small interfering RNAs (siRNAs). Thirty-two male dyslipidemic type 2 diabetic rats (ZFDM LepR^fa/fa) were fed a high-cholesterol diet w/wo XaI (50 µg/day/kg) for 1–4 weeks. Results: SA-β-gal, p53, p21, and p16^INK4a were increased by HG and restored by XaI (50 nM) in HUVECs. XaI restored telomerase activity and preserved telomere length. XaI suppressed O₂^–, p22^phox, and ICAM1 and restored NOx and eNOS. XaI decreased PAR1 following elevation by HG, which was confirmed by PAR1 siRNA and PAR2 siRNA. In in vivo experiments, plasma glucose, total cholesterol, and triglycerides were increased for 4 weeks but were not changed by XaI. XaI decreased SA-β-gal and telomerase and preserved telomere length in the aortic endothelium. XaI activated eNOS, inhibited p22^phox, increased plasma NOx, and decreased O₂^–. Conclusion: Rivaroxaban prevents replicative senescence in HUVECs and aortic endothelial cells in dyslipidemic diabetic mice. It restores endothelial function and prevents the progression of atherosclerosis.

Structural Insights into the Activation of Blood Coagulation Factor XI Zymogen by Thrombin: A Computational Molecular Dynamics Study

Activation of human blood coagulation factor XI zymogen into fXIa plays a significant role in the upstream coagulation pathway in which fXIa activates fIX zymogen into active fIX. The mechanistic details of how fXI gets activated by the key activating enzyme thrombin are not well-understood at atomic level, despite a wealth of reported experimental biochemical data. In this study, we provide a structural model for the interactions of thrombin enzyme with FXI zymogen that represent the initial acylation step of the serine-protease hydrolysis by employing protein-protein docking and explicit-solvent MD simulations for 2 microseconds. The proposed complex model between the thrombin enzyme and FXI substrate reveals that the activation of FXI is mediated by thrombin's anion binding exosite-2 (ABE2) interactions with A3 and A4 domains. We predict that Arg409 and Arg413 of ABE2 play critical role in mediating the interaction of thrombin with FXI. The insertion loop 60 of thrombin is also seen to interact with both apple and SP domains of FXI. The binding free-energy of interaction of the wild-type and four mutants of FXI with thrombin are also estimated to ascertain the relative importance of ABE2 of thrombin.

Nanoparticles Can Wrap Epithelial Cell Membranes and Relocate Them Across the Epithelial Cell Layer.

Although the link between the inhalation of nanoparticles and cardiovascular disease is well established, the causal pathway between nanoparticle exposure and increased activity of blood coagulation factors remains unexplained. To initiate coagulation tissue factor bearing epithelial cell membranes should be exposed to blood, on the other side of the less than a micrometre thin air-blood barrier. For the inhaled nanoparticles to promote coagulation, they need to bind lung epithelial-cell membrane parts and relocate them into the blood. To assess this hypothesis, we use advanced microscopy and spectroscopy techniques to show that the nanoparticles wrap themselves with epithelial-cell membranes, leading to the membrane’s disruption. The membrane-wrapped nanoparticles are then observed to freely diffuse across the damaged epithelial cell layer relocating epithelial cell membrane parts over the epithelial layer. Proteomic analysis of the protein content in the nanoparticles wraps/corona finally reveals the presence of the coagulation-initiating factors, supporting the proposed causal link between the inhalation of nanoparticles and cardiovascular disease.

Perioperative Management of Patients with Hemophilia during Spinal Surgery.

Study DesignSingle-center retrospective study.PurposeTo optimize the perioperative management of patients with hemophilia who are undergoing spinal surgery.Overview of LiteratureHemophilia is a rare disease in which there is a tendency of bleeding because of a congenital deficiency in blood coagulation factor activity. There has been no previous report on spinal surgery in patients with hemophilia.MethodsThe subjects were five patients (all males) with hemophilia who underwent spinal surgery at Nagoya University Hospital. Two patients had hemophilia A (deficiency of factor VIII) and three had hemophilia B (deficiency of factor IX). The mean age at the time of surgery was 63 years (range, 46–73 years). The following surgeries were performed: posterior lumbar interbody fusion (PLIF) in two patients, and lumbar fenestration, cervical laminoplasty and lumbar fenestration, and cervical laminoplasty and PLIF in one patient each.ResultsCoagulation factor at a mean dose of 4.8 ×103 U (range, 3–6 ×103 U) was intravenously injected before surgery, and a mean dose of 5.2 ×103 U (rang, 4–6 ×103 U) was continuously administered for 24 hours after surgery. Factor activity was maintained at ≥80% until postoperative day 14 and at ≥50% thereafter. The average duration of surgery was 178 minutes (range, 133–233 minutes), the estimated blood loss was 661 mL (range, 272–1,344 mL), and a drain tube was left subfascially in place for 2 days in all patients. Reoperation due to postoperative surgical site infection was required in one patient, but there were no complications due to hemorrhagic diathesis. The total dose of coagulation factor administered during hospitalization was 102 ×103 U (range, 46–198 ×103 U).ConclusionsCoordination with a hematologist and dose adjustment of the coagulation factor preparation to maintain a target level of coagulation factor activity facilitated a smooth postoperative course with perioperative control of bleeding during spinal surgery for patients with hemophilia.

Adaptive release of heparin from anticoagulant hydrogels triggered by different blood coagulation factors.

Feedback-controlled anticoagulant hydrogels were formed by crosslinking the anticoagulant heparin with star-shaped poly(ethylene glycol) using peptide linkers, which are selectively cleaved by different activated blood coagulation factors acting as proteolytic enzymes. Various cleavable peptide units, differing either in their thrombin turnover rates or in their responsiveness to factors activated earlier in the course of blood coagulation, were used for the formation of the biohybrid materials. Release triggered by the early coagulation factors Xa (FXa) or FXIIa/kallikrein was shown to enhance the efficiency of the released anticoagulant. Furthermore, FXa-cleavable gels enabled a faster release of heparin, which was attributed to the lower affinity of the factor for heparin. Combining early and fast responses, FXa-cleavable gels were shown to provide anticoagulant protection of biomaterial surfaces at low levels of released heparin in human whole-blood incubation experiments. The results demonstrate the potential for employing biomolecular circuits in the design of functional biomaterials to tailor the adaptive delivery of bioactive molecules.

Novel enzymatically cross-linked hyaluronan hydrogels support the formation of 3D neuronal networks

Hyaluronan (HA) is an essential component of the central nervous system's extracellular matrix and its high molecular weight (MW) form has anti-inflammatory and anti-fibrotic properties relevant for regenerative medicine. Here, we introduce a new hydrogel based on high MW HA which is cross-linked using the transglutaminase (TG) activity of the activated blood coagulation factor XIII (FXIIIa). These HA-TG gels have significant advantages for neural tissue engineering compared to previous HA gels. Due to their chemical inertness in the absence of FXIIIa, the material can be stored long-term, is stable in solution, and shows no cytotoxicity. The gelation is completely cell-friendly due to the specificity of the enzyme and the gelation rate can be tuned from seconds to hours at physiological pH and independently of stiffness. The gels are injectable, and attach covalently to fibrinogen and fibrin, two common bioactive components in in vitro tissue engineering, as well as proteins present in vivo, allowing the gels to covalently bind to brain or spinal cord defects. These optimal chemical and bioactive properties of HA-TG gels enabled the formation of 3D neuronal cultures of unprecedented performance, showing fast neurite outgrowth, axonal and dendritic speciation, strong synaptic connectivity in 3D networks, and rapidly-occurring and long-lasting coordinated electrical activity.

Snake Venom Metalloproteinases

Abstract As more data are generated from proteome and transcriptome analysis revealing that metalloproteinases represent most of the Viperid and Colubrid venom components authors decided to describe in a short review a classification and some of the multiple activities of snake venom metalloproteinases. SVMPs are classified in three major classes (P-I, P-II and P-III classes) based on the presence of various domain structures and according to their domain organization. Furthermore, P-II and P-III classes were separated in subclasses based on distinctive post-translational modifications. SVMPs are synthesized in a latent form, being activated through a Cys-switch mechanism similar to matrix metalloproteinases. Most of the metalloproteinases of the snake venom are responsible for the hemorrhagic events but also have fibrinogenolytic activity, poses apoptotic activity, activate blood coagulation factor II and X, inhibit platelet aggregation, demonstrating that SVMPs have multiple functions in addition to well-known hemorrhagic function.

The characteristic features of the relationship of thyroid, hemostasis and lipid peroxidation

In recent years, it is experimentally confirmed the change of activity of blood coagulation factors in hypothyroidism, connection of lipid peroxidation-thyroid (LP-T) with hemostasis: T3 inhibits peroxidation in microsomal fraction of hepatocytes thyroliberyn limits the accumulation of LP products, concentration of enzymes-antioxidant varies at different stages of thyroid lesions, especially in thyroid oncology - accumulation of LP products. This indicates that the thyroid regulates the LP processes and its operation depends on the LP

Cluster III of low-density lipoprotein receptor-related protein 1 binds activated blood coagulation factor VIII.

Low-density lipoprotein receptor-related protein 1 (LRP) mediates clearance of blood coagulation factor VIII (FVIII). In LRP, FVIII binds the complement-type repeats (CRs) of clusters II and IV, which also bind a majority of other LRP ligands. No ligand is known for LRP cluster I, and only three ligands, including the LRP chaperone alpha-2 macroglobulin receptor-associated protein (RAP), bind cluster III. Using surface plasmon resonance, we found that in addition to clusters II and IV, activated FVIII (FVIIIa) binds cluster III. The specificity of this interaction was confirmed using an anti-FVIII antibody fragment, which inhibited the binding. Recombinant fragments of cluster III and its site-directed mutagenesis were used to localize the cluster's site for binding FVIIIa to CR.14-19. The interactive site of FVIIIa was localized within its A1/A3'-C1-C2 heterodimer (HDa), which is a major physiological remnant of FVIIIa. In mice, the clearance of HDa was faster than that of FVIII and prolonged in the presence of RAP, which is known to inhibit interactions of LRP with its ligands. In accordance with this, the cluster III site for RAP (CR.15-19) was found to overlap that for FVIIIa. Altogether, our findings support the involvement of LRP in FVIIIa catabolism and suggest a greater significance of the biological role of cluster III compared to that previously known.