INFLUENCE OF VARIOUS THROMBIN FORMATION RATES ON THE FIBRIN STABILIZATION PROCESS

SummaryClinical trials suggest that the risk of thrombosis during coronary angioplasty is lower with ionic contrast agents than with nonionic contrast agents. However, the molecular mechanisms underlying this effect are unknown. This study examined the effects of contrast agents on thrombin formation and its interaction with substrates, inhibitors, and ligands to define potential mechanisms by which contrast agents affect thrombus formation. Two ionic agents, diatrizoate and ioxaglate, and one nonionic agent, ioversol, were studied. Ionic agents inhibited factor X activation by the tissue factor-factor VIIa complex more potently than ioversol (53 ± 3.7, 43.0 ± 1.9, and 26.5 ± 2.4% inhibition by diatrizoate, ioxaglate, and ioversol, respectively, at concentrations of 5%). Ionic contrast agents were potent inhibitors of prothrombinase function, inhibiting thrombin formation by >75% at contrast concentrations of 0.6% (p <0.005). Ioversol inhibited prothrombinase to a significantly lesser extent than ionic agents. Clotting assays suggested that ioxaglate was the most potent inhibitor of thrombin generation in plasma despite having the least effect on fibrin polymerization. Contrast agents inhibited binding of thrombin to fibrin, with ionic agents producing a more potent effect than ioversol (p <0.02). However, contrast agents did not inhibit thrombin-mediated platelet activation, had only a minor effect on inhibition of thrombin by antithrombin III, and did not affect thrombin-hirudin interactions. In summary, these studies identify specific mechanisms by which radiographic contrast agents inhibit thrombin formation and function – i.e. inhibition of tissue factor-dependent factor Xa generation, inhibition of the prothrombinase complex, and inhibition of thrombin binding to fibrin. These findings may help to explain the reduced risk of thrombosis during coronary angioplasty associated with ionic contrast agents.

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Anticoagulant Activity of β2-Glycoprotein I Is Potentiated by a Distinct Subgroup of Anticardiolipin Antibodies

Thrombosis and Haemostasis ◽

10.1055/s-0038-1656368 ◽

1992 ◽

Vol 68 (03) ◽

pp. 297-300 ◽

Cited By ~ 130

Author(s):

Monica Galli ◽

Paul Comfurius ◽

Tiziano Barbui ◽

Robert F A Zwaal ◽

Edouard M Bevers

Keyword(s):

Human Plasma ◽

Anticoagulant Activity ◽

Factor Xa ◽

Type A ◽

Lipid Vesicles ◽

Dependent Manner ◽

Type B ◽

Distinct Subgroup ◽

Glycoprotein I ◽

Thrombin Formation

SummaryPlasmas of 16 patients positive for both IgG anticardiolipin (aCL) antibodies and lupus anticoagulant (LA) antibodies were subjected to adsorption with liposomes containing cardiolipin. In 5 of these plasmas both the anticardiolipin and the anticoagulant activities were co-sedimented with the liposomes in a dose-dependent manner, whereas in the remaining cases only the anticardiolipin activity could be removed by the liposomes, leaving the anticoagulant activity (LA) in the supernatant plasma. aCL antibodies purified from the first 5 plasmas were defined as aCL-type A, while the term aCL-type B was used for antibodies in the other 11 plasmas, from which 2 were selected for this study.Prolongation of the dRVVT was produced by affinity-purified aCL-type A antibodies in plasma of human as well as animal (bovine, rat and goat) origin. aCL-type B antibodies were found to be devoid of anticoagulant activity, while the corresponding supernatants containing LA IgG produced prolongation of the dRVVT only in human plasma.These anticoagulant activities of aCL-type A and of LA IgG's were subsequently evaluated in human plasma depleted of β2-glycoprotein I (β2-GPI), a protein which was previously shown to be essential in the binding of aCL antibodies to anionic phospholipids. Prolongation of the dRVVT by aCL-type A antibodies was abolished using β2-GPI deficient plasma, but could be restored upon addition of β2-GPI. In contrast, LA IgG caused prolongation of the dRVVT irrespective of the presence or absence of β2-GPI.Since β2-GPI binds to negatively-charged phospholipids and impedes the conversion of prothrombin by the factor Xa/Va enzyme complex (Nimpf et al., Biochim Biophys Acta 1986; 884: 142–9), comparison was made of the effect of aCL-type A and aCL-type B antibodies on the rate of thrombin formation in the presence and absence of β2-GPI. This was measured in a system containing highly purified coagulation factors Xa, Va and prothrombin and lipid vesicles composed of 20 mole% phosphatidylserine and 80 mole% phosphatidylcholine. No inhibition on the rate of thrombin formation was observed with both types of aCL antibodies when either β2-GPI or the lipid vesicles were omitted. Addition of β2-GPI to the prothrombinase assay in the presence of lipid vesicles causes a time-dependent inhibition which was not affected by the presence of aCL-type B or non-specific IgG. In contrast, the presence of aCL-type A antibodies dramatically increased the anticoagulant effect of β2-GPI. These data indicate that the anticoagulant activity of aCL-type A antibodies in plasma is mediated by β2-GPI.

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Strength Changes in Peat-Polymer Stabilization Process

International Journal of Integrated Engineering ◽

10.30880/ijie.2018.10.09.007 ◽

2018 ◽

Vol 10 (9) ◽

Cited By ~ 1

Author(s):

Siti Nooraiin Mohd Razali ◽

◽

Adnan Zainorabidin ◽

Ismail Bakar ◽

Habib Musa Mohamad ◽

...

Keyword(s):

Stabilization Process ◽

Polymer Stabilization

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Civil Military Relation and Stabilization in Federally Administered Tribal Areas (FATA), Pakistan

NUST Journal of International Peace and Stability ◽

10.37540/njips.v2i2.35 ◽

2019 ◽

Author(s):

Tughral Yamin

Keyword(s):

Paper Briefly ◽

Conflict Zones ◽

Stabilization Process ◽

Civil Military Relations ◽

Salient Points ◽

Military Relations ◽

The Military ◽

Tribal Areas

The importance of civil military relations assumes seminal importance in ensuring the success of all phases of a counter insurgency campaign. In the true tradition of the Clausewitzian dictum that war is the continuation of policy and vice versa; Pakistan Army has been employed as a matter of policy in counter insurgency operations in the erstwhile tribal areas. They have also been used in the stabilization operations to bring about normality in the insurgency ridden areas. In fact the employment of Pakistan Army in the stabilization process defies any previous example in any other country. In all phases of the conflict cycle, the military has worked hand in glove with its civilian counterparts. The civil-military coordination (CIMIC) in the insurgency ridden areas has taken place within the framework of the established ground rules of an organized counter insurgency campaign. It would not be unfair to say that the return to normality in the erstwhile FATA has only been possible because of a well-knit CIMIC architecture. This paper briefly explicates the salient points of the CIMIC aspect of the counter and post-insurgency part of the operations in the conflict zones and highlights the importance of this aspect of dealing with insurgencies.

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The Stabilization Process Then and Now

10.1093/oso/9780190698980.003.0008 ◽

2018 ◽

Author(s):

Ben Epstein

Keyword(s):

Political Communication ◽

Status Quo ◽

The Political ◽

The Internet ◽

Stabilization Process ◽

The Third ◽

Stabilization Phase ◽

Over Time

This chapter shifts the focus to the third and final stabilization phase of the political communication cycle (PCC). During the stabilization phase, a new political communication order (PCO) takes shape through the building of norms, institutions, and regulations that serve to fix the newly established status quo in place. This status quo occurs when formerly innovative political communication activities become mundane, yet remain powerful. Much of the chapter details the pattern of communication regulation and institution construction over time. In particular, this chapter explores the instructive similarities and key differences between the regulation of radio and the internet, which offers important perspectives on the significance of our current place in the PCC and the consequences of choices that will be made over the next few years.

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Ouput Voltage Stabilization Process Simulation in Generator with Hybrid Excitation at Variable Drive Speed

2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) ◽

10.1109/ukrcon.2019.8879781 ◽

2019 ◽

Cited By ~ 2

Author(s):

Mykola Ostroverkhov ◽

Vadim Chumack ◽

Eugene Monakhov

Keyword(s):

Process Simulation ◽

Voltage Stabilization ◽

Stabilization Process ◽

Hybrid Excitation ◽

Drive Speed

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The procoagulant effects of factor V Leiden may be balanced against decreased levels of factor V and do not reflect in vivo thrombin formation in newborns

Thrombosis and Haemostasis ◽

10.1160/th05-05-0375 ◽

2006 ◽

Vol 95 (03) ◽

pp. 434-440 ◽

Cited By ~ 4

Author(s):

Satu Hyytiäinen ◽

Ulla Wartiovaara-Kautto ◽

Veli-Matti Ulander ◽

Risto Kaaja ◽

Markku Heikinheimo ◽

...

Keyword(s):

Tissue Factor ◽

Platelet Rich Plasma ◽

Venous Blood ◽

Factor V Leiden ◽

Factor V ◽

Cord Plasma ◽

Adult Plasma ◽

Thrombin Formation

SummaryThrombin regulation in newborns remains incompletely understood.We studied tissue factor-initiated thrombin formation in cord plasma in vitro, and the effects of Factor VLeiden (FVL) heterozygosity on thrombin regulation both in vitro and in vivo in newborns. Pregnant women with known thrombophilia (n=27) were enrolled in the study. Cord blood and venous blood at the age of 14 days were collected from 11 FVL heterozygous newborns (FVL-positive) and from 16 FVL-negative newborns. Prothrombin fragment F1+2 and coagulation factors were measured. Tissue factor-initiated thrombin formation was studied in cord platelet-poor plasma (PPP) of FVL-negative and -positive newborns, and in both PPP and platelet-rich plasma (PRP) of healthy controls. The endogenous thrombin potential (ETP) in cord PPP or PRP was ∼60% of that in adult plasma, while thrombin formation started ∼55% and ∼40% earlier in cord PPP and PRP, respectively. Further, in FVL-positive newborns thrombin formation started significantly earlier than in FVL-negative newborns. Exogenous activated protein C (APC) decreased ETP significantly more in cord than in adult PRP. In FVL-negative cord plasma 5nM APC decreased ETP by 17.4±3.5% (mean±SEM) compared with only 3.5±3.8% in FVL-positive cord plasma (p=0.01). FVL-positive newborns showed similar levels of F1+2 but significantly decreased levels of factor V compared with FVL negative newborns both in cord plasma (FV 0.82±0.07 U/ml vs. 0.98±0.05 U/ml, p=0.03) and at the age of two weeks (FV 1.15±0.04 U/ml vs. 1.32±0.05 U/ml, p=0.03). In conclusion, newborn plasma showed more rapid thrombin formation and enhanced sensitivity to APC compared with adult plasma. FVL conveyed APC resistance and a procoagulant effect in newborn plasma. Lack of elevated F1+2 levels in FVL-positive infants, however, suggested the existence of balancing mechanisms; one could be the observed lower level of factor V in FVL heterozygous newborns.

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