scholarly journals Increased histone-DNA complexes and endothelial-dependent thrombin generation in severe COVID-19

2021 ◽  
pp. 106950
Author(s):  
Beth A. Bouchard ◽  
Christos Colovos ◽  
Michael A. Lawson ◽  
Zachary T. Osborn ◽  
Adrian M. Sackheim ◽  
...  
Keyword(s):  
Thrombin Generation ◽  
Dna Complexes

Critical role of neutrophil extracellular traps (NETs) in patients with Behcet’s disease

2019 ◽  
Vol 78 (9) ◽  
pp. 1274-1282 ◽  
Author(s):  
Alexandre Le Joncour ◽  
Raphael Martos ◽  
Stephane Loyau ◽  
Nicolas Lelay ◽  
Antoine Dossier ◽  
...  
Keyword(s):  
Behçet’S Disease ◽  
Thrombin Generation ◽  
Behcet’S Disease ◽  
Behçet's Disease ◽  
Neutrophil Extracellular Traps ◽  
Dna Complexes ◽  
Thrombotic Risk ◽  
Behcet's Disease ◽  
Extracellular Traps

ObjectivesBehçet’s disease (BD) is a chronic systemic vasculitis. Thrombosis is a frequent and life-threatening complication. The pathogenesis of BD is poorly understood and evidence supporting a role for primed neutrophils in BD-associated thrombotic risk is scant. To respond to inflammatory insults, neutrophils release web-like structures, known as neutrophil extracellular traps (NETs), which are prothrombotic. We evaluated the role of NETs and markers of NETs in BD.MethodsBlood samples were collected from patients with BD, according to the International Study Group Criteria for Behçet's disease, and healthy donors (HD). NET components, including cell-free DNA (CfDNA) and neutrophil enzymes myeloperoxidase (MPO), were assessed in serum or in purified neutrophils from patients with BD and HD.ResultsPatients with active BD had elevated serum cfDNA levels and MPO-DNA complexes compared with patients with inactive BD and to HD. In addition, levels of cfDNA and MPO-DNA complexes were significantly higher in patients with BD with vascular involvement compared with those without vascular symptoms. Purified neutrophils from patients with BD exhibited spontaneous NETosis compared with HD. Thrombin generation in BD plasma was significantly increased and positively correlated with the levels of MPO-DNA complexes and cfDNA. Importantly, DNAse treatment significantly decreased thrombin generation in BD plasma but not in HD plasma. In addition, biopsy materials obtained from patients with BD showed NETs production in areas of vasculitic inflammation and thrombosis.ConclusionsOur data show that NETs and markers of NETS levels are elevated in patients with BD and contribute to the procoagulant state. Targeting NETs may represent a potential therapeutic target for the reduction or prevention of BD-associated thrombotic risk.

scholarly journals Increased Histone-DNA Complexes and Endothelial-Dependent Thrombin Generation in Severe COVID-19

2021 ◽  
Author(s):  
Beth A. Bouchard ◽  
Christos Colovos ◽  
Michael Lawson ◽  
Adrian Sackhiem ◽  
Kara J. Mould ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Lag Time ◽  
Healthy Controls ◽  
Plasma Samples ◽  
Dna Complexes ◽  
Endogenous Thrombin Potential ◽  
Lag Times ◽  
Fibrin Structure

Objective: Coagulopathy in severe COVID-19 is common but poorly understood. The purpose of this study was to determine how SARS-CoV-2 infection impacts histone levels, fibrin structure, and endogenous thrombin potential in the presence and absence of endothelial cells. Approach: We studied individuals with SARS-CoV-2 infection and acute respiratory distress syndrome at the time of initiation of mechanical ventilation compared to healthy controls. Blood samples were assayed for levels of histone-DNA complexes. Confocal microscopy was used to evaluate fibrin structure in clots formed from recalcified plasma samples using fluorescently-labeled fibrinogen. Endogenous thrombin potential was measured by calibrated automated thrombin assays in the presence of tissue factor and phospholipid (PCPS) or cultured human endothelial cells. Results: Circulating nucleosomes were elevated in the plasma of COVID-19 patients relative to healthy controls (n=6, each group). COVID-19 patient plasma thrombin generation was also altered. Despite having an increased endogenous thrombin potential, patient plasma samples exhibited prolonged lag times and times to peak thrombin in the presence of added tissue factor and PCPS. Strikingly different results were observed when endothelial cells were used in place of tissue factor and PCPS. Control plasma samples did not generate measurable thrombin (lag time >60 min); in contrast, plasma samples from COVID-19+ patients generated thrombin (mean lag time ~20 min). Consistent with the observed alterations in thrombin generation, clots from COVID-19 subjects exhibited a denser fibrin network, thinner fibers and lower fibrin resolvability. Conclusions: Elevated histones, aberrant fibrin formation, and increased endothelial-dependent thrombin generation in COVID-19 may contribute to coagulopathy.

Torus Circumference and Thickness Parameters From a Linear DNA Size Series Suggest How Toruses Self-Assemble

1985 ◽  
Vol 43 ◽  
pp. 522-523
Author(s):  
George C. Ruben ◽  
Kenneth A. Marx
Keyword(s):  
Tertiary Structure ◽  
Dna Complexes ◽  
Tertiary Structures ◽  
Self Assembling ◽  
Double Stranded Dna ◽  
Calf Thymus ◽  
Dna Organization ◽  
Condensed Dna ◽  
Dna Size

Certain double stranded DNA bacteriophage and viruses are thought to have their DNA organized into large torus shaped structures. Morphologically, these poorly understood biological DNA tertiary structures resemble spermidine-condensed DNA complexes formed in vitro in the total absence of other macromolecules normally synthesized by the pathogens for the purpose of their own DNA packaging. Therefore, we have studied the tertiary structure of these self-assembling torus shaped spermidine- DNA complexes in a series of reports. Using freeze-etch, low Pt-C metal (10-15Å) replicas, we have visualized the microscopic DNA organization of both calf Thymus( CT) and linear 0X-174 RFII DNA toruses. In these structures DNA is circumferentially wound, continuously, around the torus into a semi-crystalline, hexagonal packed array of parallel DNA helix sections.

Thrombin generation and inhibition in the mediation of ischemic neuronal death

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S19-S19
Author(s):  
Marlise de Castro Ribeiro ◽  
Jerome Badaut ◽  
Melanie Price ◽  
Marita Meins ◽  
Julien Bogousslavsky ◽  
...  
Keyword(s):  
Neuronal Death ◽  
Thrombin Generation

Thrombin generation in paediatric patients with congenital heart disease

2008 ◽  
Vol 28 (S 01) ◽  
pp. S61-S66 ◽  
Author(s):  
G. Cvirn ◽  
A. Rosenkranz ◽  
B. Leschnik ◽  
W. Raith ◽  
W. Muntean ◽  
...  
Keyword(s):  
Congenital Heart Disease ◽  
Heart Disease ◽  
Negative Correlation ◽  
Congenital Heart ◽  
Thrombin Generation ◽  
Significant Negative Correlation ◽  
Peak Height ◽  
Global Test ◽  
Paediatric Patients ◽  
Age Range

SummaryThrombin generation was studied in paediatric patients with congenital heart disease (CHD) undergoing cardiac surgery using the calibrated automated thrombography (CAT) in terms of the lag time until the onset of thrombin formation, time to thrombin peak maximum (TTP), endogenous thrombin potential (ETP), and thrombin peak height. The suitability to determine the coagulation status of these patients was investigated. Patients, material, methods: CAT data of 40 patients with CHD (age range from newborn to 18 years) were compared to data using standard coagulation parameters such as prothrombin (FII), antithrombin (AT), tissue factor pathway inhibitor (TFPI), prothrombin fragment 1.2 (F 1.2), thrombin-antithrombin (TAT), activated partial thromboplastin time (aPTT), and prothrombin time (PT). Results: A significant positive correlation was seen between ETP and FII (p < 0.01; r = 0.369), as well as between peak height and F II (p < 0.01; r = 0.483). A significant negative correlation was seen between ETP and TFPI values (p < 0.05; r = –0.225) while no significant correlation was seen between peak height and TFPI. A significant negative correlation was seen between F 1.2 generation and ETP (p < 0.05; r = –0.254) and between F 1.2 generation and peak height (p < 0.05; r = –0.236). No correlation was seen between AT and ETP or peak. Conclusions: CAT is a good global test reflecting procoagulatory and inhibitory factors of the haemostatic system in paediatric patients with CHD.

Ancylostoma caninum Anticoagulant Peptide Blocks Metastasis In Vivo and Inhibits Factor Xa Binding to Melanoma Cells In Vitro

1998 ◽  
Vol 79 (05) ◽  
pp. 1041-1047 ◽  
Author(s):  
Kathleen M. Donnelly ◽  
Michael E. Bromberg ◽  
Aaron Milstone ◽  
Jennifer Madison McNiff ◽  
Gordon Terwilliger ◽  
...  
Keyword(s):  
Active Site ◽  
Thrombin Generation ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Melanoma Cells ◽  
Factor V ◽  
Ancylostoma Caninum ◽  
Metastatic Activity

SummaryWe evaluated the in vivo anti-metastatic activity of recombinant Ancylostoma caninum Anticoagulant Peptide (rAcAP), a potent (Ki = 265 pM) and specific active site inhibitor of human coagulation factor Xa originally isolated from bloodfeeding hookworms. Subcutaneous injection of SCID mice with rAcAP (0.01-0.2 mg/mouse) prior to tail vein injection of LOX human melanoma cells resulted in a dose dependent reduction in pulmonary metastases. In order to elucidate potential mechanisms of rAcAP’s anti-metastatic activity, experiments were carried out to identify specific interactions between factor Xa and LOX. Binding of biotinylated factor Xa to LOX monolayers was both specific and saturable (Kd = 15 nM). Competition experiments using antibodies to previously identified factor Xa binding proteins, including factor V/Va, effector cell protease receptor-1, and tissue factor pathway inhibitor failed to implicate any of these molecules as significant binding sites for Factor Xa. Functional prothrombinase activity was also supported by LOX, with a half maximal rate of thrombin generation detected at a factor Xa concentration of 2.4 nM. Additional competition experiments using an excess of either rAcAP or active site blocked factor Xa (EGR-Xa) revealed that most of the total factor Xa binding to LOX is mediated via interaction with the enzyme’s active site, predicting that the vast majority of cell-associated factor Xa does not participate directly in thrombin generation. In addition to establishing two distinct mechanisms of factor Xa binding to melanoma, these data raise the possibility that rAcAP’s antimetastatic effect in vivo might involve novel non-coagulant pathways, perhaps via inhibition of active-site mediated interactions between factor Xa and tumor cells.

Fibrinogen and its Derivatives: Cofactors in the Intrinsic Generation of Thrombin

1976 ◽  
Vol 35 (02) ◽  
pp. 305-313 ◽  
Author(s):  
D.C Triantaphyllopoulos ◽  
L.T Ryan
Keyword(s):  
Factor Viii ◽  
Vitamin K ◽  
Bovine Serum ◽  
Thrombin Generation ◽  
Factor V ◽  
Simultaneous Addition ◽  
Lower Effect

SummaryThe simultaneous addition of suboptimal concentrations of factor VIII and intact or plas-min-lysed fibrinogen into mixtures of the vitamin K dependent factors, phospholipids, adsorbed bovine serum (supplier of factor V) and calcium, increased the amount of thrombin which was generated three to twenty times over the sum of the amounts which were generated when factor VIII, or fibrinogen, or its derivatives were added separately into the thrombin generating mixture. When factor VIII was added together with both fibrinogen and its derivatives, the amount of thrombin generated was even greater, about 130% larger than the amount which was generated in the presence of equal concentrations of only intact fibrinogen plus factor VIII. Addition of albumin instead of fibrinogen or its derivatives has a similar but significantly lower effect on thrombin generation. It appears, therefore, that both intact fibrinogen and its plasminolytic derivatives, singly or in combination, and to a lesser extent albumin, act as cofactors in the reaction which is regulated by factor VIII.

Investigation of the Interaction of Blood Platelets with the Coagulation System at the Site of Plug Formation In Vivo in Man - Effect of Low-Dose Aspirin

1987 ◽  
Vol 57 (01) ◽  
pp. 062-066 ◽  
Author(s):  
P A Kyrle ◽  
J Westwick ◽  
M F Scully ◽  
V V Kakkar ◽  
G P Lewis
Keyword(s):  
Platelet Activation ◽  
Thrombin Generation ◽  
Low Dose ◽  
Bleeding Time ◽  
Blood Platelets ◽  
Dose Aspirin ◽  
Low Dose Aspirin ◽  
Plug Formation ◽  
Granule Release

SummaryIn 7 healthy volunteers, formation of thrombin (represented by fibrinopeptide A (FPA) generation, α-granule release (represented by β-thromboglobulin [βTG] release) and the generation of thromboxane B2 (TxB2) were measured in vivo in blood emerging from a template bleeding time incision. At the site of plug formation, considerable platelet activation and thrombin generation were seen within the first minute, as indicated by a 110-fold, 50-fold and 30-fold increase of FPA, TxB2 and PTG over the corresponding plasma values. After a further increase of the markers in the subsequent 3 minutes, they reached a plateau during the fourth and fifth minute. A low-dose aspirin regimen (0.42 mg.kg-1.day-1 for 7 days) caused >90% inhibition of TxB2formation in both bleeding time blood and clotted blood. At the site of plug formation, a-granule release was substantially reduced within the first three minutes and thrombin generation was similarly inhibited. We conclude that (a) marked platelet activation and considerable thrombin generation occur in the early stages.of haemostasis, (b) α-granule release in vivo is partially dependent upon cyclo-oxygenase-controlled mechanisms and (c) thrombin generation at the site of plug formation is promoted by the activation of platelets.

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