Evaluation of N8-GP Activity Using a One-Stage Clotting Assay: A Single-Center Experience

2019 ◽  
Vol 143 (5) ◽  
pp. 504-508 ◽  
Author(s):  
Inga Hegemann ◽  
Karin Koch ◽  
Wan Hui Ong Clausen ◽  
Mirella Ezban ◽  
Brigitte Brand-Staufer
Keyword(s):  
Human Plasma ◽  
One Stage ◽  
Single Center Experience ◽  
Fviii Activity ◽  
Previously Treated Patients ◽  
Normal Human ◽  
Previously Treated ◽  
Aptt Reagent ◽  
Few Data ◽  
Good Agreement

N8-GP (ESPEROCT®; turoctocog alfa pegol; Novo Nordisk A/S, Bagsvaerd, Denmark) is an extended half-life recombinant factor VIII (FVIII) molecule. FVIII-deficient plasma spiked with N8-GP can be accurately measured using many activated partial thromboplastin time (aPTT)-based one-stage clotting assay reagents with normal human plasma calibrators. To date, there are few data on the measurement accuracy of samples from patients treated with N8-GP. Here, we measure patient samples during routine treatment monitoring. Three previously treated patients with severe hemophilia A (HA) without inhibitors (baseline FVIII activity <0.01 IU/mL) received 50 IU/kg N8-GP every fourth day or twice weekly over 5 years as part of the pathfinder2 trial. Patient samples were monitored using the Pathromtin® SL aPTT reagent (Siemens Healthcare GmbH, Erlangen, Germany), a BCS® XP System analyzer (Siemens), and Standard Human Plasma (Siemens) or product-specific calibrators. Patient age ranged from 36 to 62 years. Overall, measurements performed using product-specific or Standard Human Plasma calibrators were in good agreement, with ratios randomly distributed around 1.0. Peak ratios tended to be closer to 1.0 than trough samples. Pathromtin® SL with Standard Human Plasma calibrator consistently and accurately measured FVIII activity in samples from severe HA patients receiving N8-GP prophylaxis.

Performances of an Artificial Reagent for the One-stage Factor IX Assay

1975 ◽  
Vol 33 (03) ◽  
pp. 547-552 ◽  
Author(s):  
L Meunier ◽  
J. P Allain ◽  
D Frommel
Keyword(s):  
Human Plasma ◽  
Factor Ix ◽  
Severe Haemophilia ◽  
Normal Human Plasma ◽  
Haemophilia B ◽  
One Stage ◽  
Normal Human ◽  
The One

SummaryA mixture of adsorbed normal human plasma and chicken plasma was prepared as reagent for factor IX measurement using a one-stage method. The substrate was found to be specific for factor IX. Its performances tested on samples displaying factor IX activity ranging from <l%–2,500% compared favorably with those obtained when using the plasma of severe haemophilia B patients as substrate.

Plasma Components which Interfere with Ristocetin-induced Platelet Aggregation

1975 ◽  
Vol 33 (03) ◽  
pp. 540-546 ◽  
Author(s):  
Robert F Baugh ◽  
James E Brown ◽  
Cecil Hougie
Keyword(s):  
Platelet Aggregation ◽  
Human Plasma ◽  
Plasma Proteins ◽  
Binding Protein ◽  
Plasma Heating ◽  
Protein S ◽  
Fold Increase ◽  
Normal Human Plasma ◽  
Preliminary Examination ◽  
Normal Human

SummaryNormal human plasma contains a component or components which interfere with ristocetin-induced platelet aggregation. Preliminary examination suggests a protein (or proteins) which binds ristocetin and competes more effectively for ristocetin than do the proteins involved in ristocetin-induced platelet aggregation. The presence of this protein in normal human plasma also prevents ristocetin-induced precipitation of plasma proteins at levels of ristocetin necessary to produce platelet aggregation (0.5–2.0 mg/ml). Serum contains an apparent two-fold increase of this component when compared with plasma. Heating serum at 56° for one hour results in an additional 2 to 4 fold increase. The presence of a ristocetin-binding protein in normal human plasma requires that this protein be saturated with ristocetin before ristocetin-induced platelet aggregation will occur. Variations in the ristocetin-binding protein(s) will cause apparent discrepancies in ristocetin-induced platelet aggregation in normal human plasmas.

Analysis of Intrinsic Fibrinolysis in Human Plasma Induced by Dextran Sulfate

1992 ◽  
Vol 67 (04) ◽  
pp. 440-444 ◽  
Author(s):  
Hiroko Tsuda ◽  
Toshiyuki Miyata ◽  
Sadaaki Iwanaga ◽  
Tetsuro Yamamoto
Keyword(s):  
Molecular Weight ◽  
Human Plasma ◽  
Dextran Sulfate ◽  
Tissue Type ◽  
Factor Xii ◽  
Normal Human Plasma ◽  
High Molecular Weight Kininogen ◽  
Single Chain ◽  
Major Pathway ◽  
Normal Human

SummaryThe analysis of normal human plasma by fibrin autography revealed four species of plasminogen activator (PA) activity related to tissue-type PA, factor XII, prekallikrein and urokinase-type PA (u-PA). The u-PA activity increased significantly by incubating plasma with dextran sulfate. This increase was coincident with both the cleavage of factor XII and the complex formation of activated factor XII with its plasma inhibitors, which were determined by immunoblotting procedure. The dextran sulfate-dependent activation of u-PA required both factor XII and prekallikrein, but did not require either plasminogen or factor XI. High molecular weight kininogen was required only at a low concentration of dextran sulfate. Thus the results indicate that the factor XII and prekallikrein-mediated activation of single chain u-PA (scu-PA) operates as a major pathway of scu-PA activation in whole plasma in contact with dextran sulfate.

Presence and Possible Origin of ɛ(γ-Glutamyl)Lysine Isodipeptide in Human Plasma

1992 ◽  
Vol 67 (01) ◽  
pp. 060-062 ◽  
Author(s):  
J Harsfalvi ◽  
E Tarcsa ◽  
M Udvardy ◽  
G Zajka ◽  
T Szarvas ◽  
...  
Keyword(s):  
Human Plasma ◽  
Fibrinolytic Therapy ◽  
Normal Human Plasma ◽  
Normal Human ◽  
Hplc Technique ◽  
Significant Change

Summaryɛ(γ-glutamyl)lysine isodipeptide has been detected in normal human plasma by a sensitive HPLC technique in a concentration of 1.9-3.6 μmol/1. Incubation of in vitro clotted plasma at 37° C for 12 h resulted in an increased amount of isodipeptide, and there was no further significant change when streptokinase was also present. Increased in vivo isodipeptide concentrations were also observed in hypercoagulable states and during fibrinolytic therapy.

Studies on the Thromboplastic Effect of Human Plasma Lipoproteins

1976 ◽  
Vol 35 (01) ◽  
pp. 178-185 ◽  
Author(s):  
Helena Sandberg ◽  
Lars-Olov Andersson
Keyword(s):  
High Density Lipoprotein ◽  
Human Plasma ◽  
Platelet Rich Plasma ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Plasma Lipoproteins ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Free Plasma ◽  
Good Agreement

SummaryHuman plasma lipoprotein fractions were prepared by flotation in the ultracentrifuge. Addition of these fractions to platelet-rich, platelet-poor and platelet-free plasma affected the partial thromboplastin and Stypven clotting times to various degrees. Addition of high density lipoprotein (HDL) to platelet-poor and platelet-free plasma shortened both the partial thromboplastin and the Stypven time, whereas addition of low density lipoprotein and very low density lipoprotein (LDL + VLDL) fractions only shortened the Stypven time. The additions had little or no effect in platelet-rich plasma.Experiments involving the addition of anti-HDL antibodies to plasmas with different platelet contents and measuring of clotting times produced results that were in good agreement with those noted when lipoprotein was added. The relation between structure and the clot-promoting activity of various phospholipid components is discussed.

Investigations on the Nature of Hemophilia A

1963 ◽  
Vol 09 (01) ◽  
pp. 030-052 ◽  
Author(s):  
Eberhard Mammen
Keyword(s):  
Factor Viii ◽  
Human Plasma ◽  
Barium Sulfate ◽  
Freeze Drying ◽  
Room Temperature ◽  
Hemophilia A ◽  
Normal Human Plasma ◽  
Normal Human ◽  
And Storage ◽  
Prothrombin Activation

SummaryIn this paper an inhibitor is described that is found in hemophilic plasma and serum different from any till now described inhibitor. The inhibitor only inhibits prothrombin activation in the “intrinsic clotting systems”. This inhibitor is probably not present in normal human plasma or serum. It is destroyed by ether and freeze drying, is labile to acid and storage at room temperature. It is stable upon dialysis and has not been adsorbed on barium sulfate, aluminum hydroxide or kaolin. It precipitates at 50% v/v saturation with alcohol. The nature of this inhibitor seems to be a protein or lipoprotein.Factor VIII was isolated from hemophilic plasma. The amount isolated was the same as from normal plasma and the activity properties were not different. Hemophiliacs have normal amounts of factor VIII.

A Chromogenic Factor X Assay With New Standardized Reagents

1979 ◽  
Author(s):  
P Friberger ◽  
C Lenne
Keyword(s):  
Human Plasma ◽  
Suitable Method ◽  
Chromogenic Substrate ◽  
Factor X ◽  
Normal Human Plasma ◽  
Normal Plasma ◽  
Normal Human

A recently published method for Factor X (FX) assay (1) utilizing Russel's Viper Venom (RVV) and a chromogenic substrate has been further investigated by testing a large number of parameters. This method has been considered as a suitable method for monitoring coumarol treatment (Bergström et al).The conditions for the activation of FX by purified preparations of the RVV have been studied as well as the conditions for FXa determination with a new chromogenic substrate Bz-Ile-Glu(γ-piperidyl)-Gly-Arg-pNA (S-2337). Both purified factors and normal plasma have been used. The effect of plasma inhibitors as well as the selectivity of the method has been studied.The reproducibility and stability of the different reagents and standards have been studied and found to be good.The amount of FXa activity obtained from normal human plasma has been titrated with FXa inhibitors of known purity.1) Aurell L. et al, Thromb. Res., 11, 595 (1977)2) Bergström et al, Thromb. Res., 12, 531 (1978)

A Multicenter Pharmacosurveillance Study for the Evaluation of the Efficacy and Safety of Recombinant Factor VIII in the Treatment of Patients with Hemophilia A

1997 ◽  
Vol 78 (05) ◽  
pp. 1352-1356 ◽  
Author(s):  
Emel Aygören-Pürsün ◽  
Inge Scharrer ◽  
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
Parvovirus B19 ◽  
Subjective Evaluation ◽  
Recombinant Factor Viii ◽  
Fviii Inhibitor ◽  
Previously Treated Patients ◽  
Previously Treated ◽  
Bleeding Episodes ◽  
Recombinant Fviii

SummaryIn this open multicenter study the safety and efficacy of recombinant factor VIII (rFVIII) was assessed in 39 previously treated patients with hemophilia A (factor VIII basal activity ≤15%).Recombinant FVIII was administered for prophylaxis and treatment of bleeding episodes and for surgical procedures. A total of 3679 infusions of rFVIII were given. Efficacy of rFVIII as assessed by subjective evaluation of response to infusion and mean annual consumption of rFVIII was comparable to that of plasma derived FVIII concentrates. The incremental recovery of FVIII (2.4 ± 0,83%/IU/kg, 2.12 ± 0.61%/IU/kg, resp.) was within the expected range. No clinical significant FVIII inhibitor was detected in this trial. Five of 16 susceptible patients showed a seroconversion for parvovirus B19. However, the results are ambiguous in two cases and might be explained otherwise in one further case. Thus, in two patients a reliable seroconversion for parvovirus B19 was observed.

A Hitherto Undescribed Naturally Occurring Plasma Antagonist of Activated Factor X Inhibitor (Antithrombin III)

1979 ◽  
Author(s):  
E. T. Yin ◽  
W. J. Salsgiver ◽  
O. Tangen
Keyword(s):  
Equilibrium State ◽  
Human Plasma ◽  
Antithrombin Iii ◽  
Circumstantial Evidence ◽  
Incubation Mixture ◽  
Factor X ◽  
Normal Human Plasma ◽  
Plasma Component ◽  
Naturally Occurring ◽  
Normal Human

Circumstantial evidence suggested that normal human plasma contained a substance regulating the neutralization of F.Xa by F.Xa inhibitor(XaI), (Yin et.al.,Adv.Exper. Med. & Biol., 52 : 239, 1975, Plenum Press, N.Y.).This plasma component has now been isolated and partially purified in our laboratory, and tentatively designated as “Anti-XaI”.In experiments employing purified components, when Anti-XaI was incubated at 37°C with F.Xa, Xal and heparin for two minutes at pH7.5, the amount of F.Xa inhibited was inversely proportional to the Anti-XaI concentration. But, when the F.Xa was replaced by thrombin in the incubation mixture, the neutralization of thrombin clotting activity was undisturbed.Anti-XaI was found to be neither PF3 nor PF4.These and other data strongly suggest that the “Antithrombin III pathway” is more complex than currently believed to be. In circulating blood an equilibrium state must exist between Anti-XaI and XaI.Under certain conditions when the Anti-XaI activity is predominant the rate of F.Xa neutralization bv XaI then becomes slower than the activation of prothrombin to thrombin by F.Xa.

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