Blood-Coagulation Factor VIII: Genetics, Physiological Control, and Bioassay

Ingram, G. I. C.

doi:10.1016/s0065-2423(08)60415-1

Cited by 24 publications

(30 citation statements)

References 90 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Each sample dilution was tested in duplicate. Percent FVIII activity was calculated in patient samples by the parallel curves method [20]. The index of parallelism was calculated as the ratio between slopes (normal value 0.8–1.2).…”

Section: Methodsmentioning

confidence: 99%

A multicenter pharmacokinetic study of the B-domain deleted recombinant factor VIII concentrate using different assays and standards

Morfini

Cinotti

Bellatreccia³

et al. 2003

Journal of Thrombosis and Haemostasis

View full text Add to dashboard Cite

To cite this article: Mor®ni M, Cinotti S, Bellatreccia A, Paladino E, Gringeri A, Mannucci PM and the ReFacto-AICE Study Group. A multicenter pharmacokinetic study of the B-domain deleted recombinant factor VIII concentrate using different assays and standards. J Thromb Haemost 2003; 1: 2283±9.See also Lollar P. The factor VIII assay problem neither rhyme nor reason. This issue, pp. 2275±9.Summary. When the one-stage clotting assay is used in comparison with the chromogenic and immunological assays, plasma levels of factor (F)VIII are underestimated by 40±50% after infusion of B-domain deleted recombinant FVIII (BDD-rFVIII) in patients with hemophilia. A possible way to counteract the underestimation of FVIII levels by the one-stage assay is the adoption of a recombinant FVIII reference standard instead of a plasma standard. To evaluate the usefulness of such a standard [ReFacto 1 Laboratory Standard (RLS)], the pharmacokinetic parameters of a single dose of BDD-rFVIII (25 U kg À1 ) were evaluated in a multicenter study carried out in 18 patients with severe hemophilia A. The very low in vivo recovery, obtained with the combination of the one-stage assay and plasma reference standard, was increased up to the values obtained by the chromogenic assay when the results were expressed in terms of RLS. When the plasma standard was used, the one-stage/ chromogenic ratio was 0.82 AE 0.12 for FVIII levels above 25 U dL À1 and 1.42 AE 0.99 for FVIII levels below 25 U dL À1 . Using the RLS, the one-stage/chromogenic ratio increased to 1.01 AE 0.19 at FVIII levels above 25 U dL À1 , as a consequence of a complete overlap of the two decays; however, at FVIII levels below 25 U dL À1 , the one-stage/chromogenic ratio was still 1.6 AE 0.85. After the twelfth hour, FVIII concentrations obtained by chromogenic assay were always lower than those resulting from the one-stage clotting assay, independently of the standard used. Results obtained by chromogenic assay were not affected by the type of standard used. Compared with those obtained by the one-stage assay, higher values of clearance, lower volume of distribution area and shorter plasma half-life or mean residence time were obtained by chromogenic assay because of a shape change of the decay curve due to a shift to higher values in the ®rst part (time interval 0±12 h) and to lower values in the second part of the decay curve (time interval 12±48 h). As a consequence, the slope of the decay curve obtained by means of chromogenic assay was steeper. In conclusion, the more homogeneous results of in vivo recovery and pharmacokinetic analysis, due to the decrease of discrepancy between the two methods when RLS was used, make the cheaper and more widely used one-stage assay preferable to the more expensive chromogenic assay, on condition that the ReFacto speci®c standard has used.

show abstract

Section: Methodsmentioning

confidence: 99%

A multicenter pharmacokinetic study of the B-domain deleted recombinant factor VIII concentrate using different assays and standards

Morfini

Cinotti

Bellatreccia³

et al. 2003

Journal of Thrombosis and Haemostasis

View full text Add to dashboard Cite

show abstract

“…The blood glucose measurements were performed by the method of Morley et al (1968), using an autoanalyser, the serumfreefatty acids (FFA) by a modification (Kurien & Oliver, 1966) of the colorimetric method of Mosinger (1965) and the one stagefactor-VIII assay as directed by Hardisty & Macpherson (1962) and modified by Veltkamp (1967). The factor-VIII activity was calculated on a K.D.F.9 computer using a programme based on the methods used by Ingram (1965) and Hardisty & (1962).…”

Section: Methods Of Estimationmentioning

confidence: 99%

Adrenergic Mechanisms in the Systemic Plasminogen Activator Response to Adrenaline in Man

1970

View full text Add to dashboard Cite

Summary. The effect of propranolol, ICI 50172 and a combination of propranolol and phentolamine, on the plasminogen activator response to a 30 mm intravenous infusion of adrenaline hydrochloride (0.1 μg/kg/min) has been studied in five healthy subjects. Plasma factor VIII, serum free fatty acids, blood glucose and pulse rate changes were also monitored to confirm the efficacy of adrenergic blockade. Propranolol blocked the plasminogen activator response by a factor of 29% whereas ICI 50172 had no effect. The addition of phentolamine to propranolol failed to influence further the degree of blockade already present with propranolol alone. It is postulated that the plasminogen activator response to adrenaline is derived from two separate components, and that the relatively minor one may be secondary to vasoactive changes whereas the second and major component is quite independent of this phenomenon. It is also proposed that both components may share a common adrenergic receptor site.

show abstract

“…When low concentrations of VIIIR: AG are tested, the logit transformation of percentage bound radioactivity, which gives a straight line for dilutions of normal plasma from I in 300 to I in 4000, is more conveniently used for calculation of the results. Each test sample was assayed at two dilutions at Ieast (but usually three) and VII1R:AG values were calculated as described by Ingram (1965) to avoid the arbitrary and subjective procedure of fitting by eye the dose-response curves. The first step is to determine by calculation the sloyc indices of the curves and to confirm that they are parallel.…”

Section: Ruggeri Et Nlmentioning

confidence: 99%

Immunoradiometric Assay of Factor VIII Related Antigen, with Observations in 32 Patients with von Willebrand's Disease

et al. 1976

View full text Add to dashboard Cite

A solid phase non-competitive immunoradiometric assay (IRMA) has been developed which allows measurement of factor VIII related antigen (VIIIR:AG) levels in normal plasma as low as 2.5 x 10(-4) U/ml. The assay is based on the extraction of VIIIR:AG from test plasma by means of polystrene tubes coated with a specific unlabelled anti-VIIIR:AG rabbit antiserum and subsequent labelling of the extracted antigen with 125I-labelled anti-VIIIR:AG rabbit IgG.

show abstract

Blood-Coagulation Factor VIII: Genetics, Physiological Control, and Bioassay

Cited by 24 publications

References 90 publications

A multicenter pharmacokinetic study of the B-domain deleted recombinant factor VIII concentrate using different assays and standards

A multicenter pharmacokinetic study of the B-domain deleted recombinant factor VIII concentrate using different assays and standards

Adrenergic Mechanisms in the Systemic Plasminogen Activator Response to Adrenaline in Man

Immunoradiometric Assay of Factor VIII Related Antigen, with Observations in 32 Patients with von Willebrand's Disease

Contact Info

Product

Resources

About