A Brain Extract as a Substitute for Platelet Suspensions in the Thromboplastin Generation Test

Bell, Warren N.; Alton, Harold

doi:10.1038/174880a0

Cited by 473 publications

(162 citation statements)

References 1 publication

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“…"Cephalin"-fortificd clotting tihiIC, an adaptation of the partial thromboplastin time (25) (26), diluted from its stock solution 4,000-to 8,000-fold with buffer. The stock solution was stored at -25°C.…”

Section: Methodsmentioning

confidence: 99%

Studies on the Action of Hageman Factor: Evidence That Activated Hageman Factor in Turn Activates Plasma Thromboplastin Antecedent*

Ratnoff¹,

Davie²,

Mallett³

1961

J. Clin. Invest.

201

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Section: Methodsmentioning

confidence: 99%

Studies on the Action of Hageman Factor: Evidence That Activated Hageman Factor in Turn Activates Plasma Thromboplastin Antecedent*

Ratnoff¹,

Davie²,

Mallett³

1961

J. Clin. Invest.

201

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“…For modified partial thromboplastin time (modified PTT) assays, proteases to be tested (plasma FIXa␤, rFIXa␤, or rFIXa␤/ VII-Gla) were diluted to 5 g/ml in TBSA, and serial dilutions were prepared as described above. 65 l of FIX-deficient plasma, 65 l of rabbit brain cephalin prepared by the method of Bell and Alton (33), and 65 l of the protein to be tested were mixed in a fibrin cup warmed to 37°C. 30 s later, 65 l of 25 mM CaCl 2 was added, and the time to clot formation was determined on the fibrometer.…”

Section: Determination Of Specific Activities Of Zymogen and Active Rmentioning

confidence: 99%

The Factor IX γ-Carboxyglutamic Acid (Gla) Domain Is Involved in Interactions between Factor IX and Factor XIa

Aktimur

Gabriel

Gailani

et al. 2003

Journal of Biological Chemistry

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During hemostasis, factor IX is activated to factor IXa␤ by factor VIIa and factor XIa. The glutamic acidrich ␥-carboxyglutamic acid (Gla) domain of factor IX is involved in phospholipid binding and is required for activation by factor VIIa. In contrast, activation by factor XIa is not phospholipid-dependent, raising questions about the importance of the Gla for this reaction. We examined binding of factors IX and IXa␤ to factor XIa by surface plasmon resonance. Plasma factors IX and IXa␤ bind to factor XIa with K d values of 120 ؎ 11 nM and 110 ؎ 8 nM, respectively. Recombinant factor IX bound to factor XIa with a K d of 107 nM, whereas factor IX with a factor VII Gla domain (rFIX/VII-Gla) and factor IX expressed in the presence of warfarin (rFIX-des␥) did not bind. An anti-factor IX Gla monoclonal antibody was a potent inhibitor of factor IX binding to factor XIa (K i 34 nM) and activation by factor XIa (K i 33 nM). In activated partial thromboplastin time clotting assays, the specific activities of plasma and recombinant factor IX were comparable (200 and 150 units/mg), whereas rFIX/VIIGla activity was low (<2 units/mg). In contrast, recombinant factor IXa␤ and activated rFIX/VIIa-Gla had similar activities (80 and 60% of plasma factor IXa␤), indicating that both proteases activate factor X and that the poor activity of zymogen rFIX/VII-Gla was caused by a specific defect in activation by factor XIa. The data demonstrate that factor XIa binds with comparable affinity to factors IX and IXa␤ and that the interactions are dependent on the factor IX Gla domain.

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“…The assay was carried out by incubating 50 ~1 factor Xa ([8], 0.4 U/ml), 50 ~1 prothrombin (1.5 U/ml), and 50 ~1 cephalin [9] at 37°C for 1 min. After the addition of 50 ~1 test sample, and 20 ~150 mM CaCl, the incubation was continued for another 3 min.…”

Section: Factor V Assaysmentioning

confidence: 99%

Production of blood coagulation factory V and tissue thromboplastin by macrophages in vitro

et al. 1981

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A Brain Extract as a Substitute for Platelet Suspensions in the Thromboplastin Generation Test

Cited by 473 publications

References 1 publication

Studies on the Action of Hageman Factor: Evidence That Activated Hageman Factor in Turn Activates Plasma Thromboplastin Antecedent*

Studies on the Action of Hageman Factor: Evidence That Activated Hageman Factor in Turn Activates Plasma Thromboplastin Antecedent*

The Factor IX γ-Carboxyglutamic Acid (Gla) Domain Is Involved in Interactions between Factor IX and Factor XIa

Production of blood coagulation factory V and tissue thromboplastin by macrophages in vitro

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