Corn trypsin inhibitor in fluorogenic thrombin-generation measurements is only necessary at low tissue factor concentrations and influences the relationship between factor VIII coagulant activity and thrombogram parameters.
Blood Coagul Fibrinolysis
; 19(3): 183-9, 2008 Apr.
Article
em En
| MEDLINE
| ID: mdl-18388496
ABSTRACT
The fluorogenic calibrated automated thrombin-generation assay is influenced by contact pathway activation in platelet-rich and platelet-poor plasma. This influence lessens with increasing tissue factor (TF) concentrations and is inhibited by corn trypsin inhibitor (CTI). CTI is expensive and at what TF concentration its influence becomes irrelevant is unclear. Spiking of factor VIII (FVIII)-depleted plasma with FVIII, in samples without CTI, shows a plateau of thrombin generation at low normal FVIII levels. Given the association with thrombosis at high levels, a continuing increase in thrombin generation would be expected. We studied the effect of CTI on this relation by spiking experiments up to 4.8 IU/ml at 1 pmol/l TF and compared the influence of CTI at 1 and 5 pmol/l in platelet-poor plasma. CTI significantly influences thrombin generation in platelet-poor plasma at 1 pmol/l TF (difference of means for endogenous thrombin potential of 232.5 nmol/l per min, P<0.0001) and peak of 48 nmol/l (P<0.0001)) but not at 5 pmol/l. Spiking experiments without CTI confirm the hyperbolic relation between FVIII coagulant activity (FVIIIC) and endogenous thrombin potential with a plateau at 0.70-1.40 IU/ml. With CTI, a near-linear response up to 1.0 IU/ml was found with a plateau at 2.4-4.8 IU/ml. For peak thrombin, no plateau was reached with CTI. The present study confirms and extends previous data on CTI and the relationship between FVIIIC and thrombin generation. CTI is not necessary at 5 pmol/l TF, and thrombin generation remains dependent on FVIIIC up to 4.8 IU/ml at 1 pmol/l with CTI. Higher levels than previously thought may be needed to normalize thrombin generation.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Plantas
/
Fator VIII
/
Trombina
/
Corantes Fluorescentes
Limite:
Humans
Idioma:
En
Revista:
Blood Coagul Fibrinolysis
Assunto da revista:
ANGIOLOGIA
/
HEMATOLOGIA
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Reino Unido