A Non-Stasis Rabbit Model for the Detection of Factor IX Concentrate Thrombogenicity.

1979 ◽  
Author(s):  
C.V. Prowse ◽  
A.R. Williams
Keyword(s):  
Platelet Count ◽  
Factor Viii ◽  
Partial Thromboplastin Time ◽  
Rabbit Model ◽  
Factor Ix ◽  
In Vitro Activity ◽  
Blood Samples ◽  
Intravascular Coagulation

A method has been developed whereby aerial blood samples can be obtained from a rabbit over a period of four hours following infusion of potentially thrombogenic solutions. Infusion of 50 uAg thrombin over JO minutes produced intravascular coagulation for up to three hours after infusion as demonstrated by a decrease in factor VIII, increase in partial thromboplastin time and fibrin(ogen) degradation producta and a positive ethanol gelation teat. No change in fibrinogen, factor DC or platelet count was found. Saline infusion produced no change in any of these parameters.Infusion of a variety of factor IX concentrates at 100 u/kg shewed that those concentrates active in in vitro thrombogenicity teste produced a similar effect to thrombin in vivo and in addition may result in a drop in platelet count. Infesion of concentrates with low in vitro activity did not induce intravascular coagulation.

scholarly journals A mutated factor X activatable by thrombin corrects bleedings in vivo in a rabbit model of antibody-induced hemophilia A

Haematologica ◽  
2019 ◽  
Vol 105 (9) ◽  
pp. 2335-2340
Author(s):  
Toufik Abache ◽  
Alexandre Fontayne ◽  
Dominique Grenier ◽  
Emilie Jacque ◽  
Alain Longue ◽  
...  
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
Factor Viia ◽  
Rabbit Model ◽  
Coagulation Factor ◽  
Factor Ix ◽  
Factor X ◽  
Factor Viiia

Rendering coagulation factor X sensitive to thrombin was proposed as a strategy that can bypass the need for factor VIII. In this paper, this non-replacement strategy was evaluated in vitro and in vivo in its ability to correct factor VIII but also factor IX, X and XI deficiencies. A novel modified factor X, named Actiten, was generated and produced in the HEK293F cell line. The molecule possesses the required post-translational modifications, partially keeps its ability to be activated by RVV-X, factor VIIa/tissue factor, factor VIIIa/factor IXa and acquires the ability to be activated by thrombin. The potency of the molecule was evaluated in respective deficient plasmas or hemophilia A plasmas, for some with inhibitors. Actiten corrects dose dependently all the assayed deficient plasmas. It is able to normalize the thrombin generation at 20 μg/mL showing however an increased lagtime. It was then assayed in a rabbit antibody-induced model of hemophilia A where, in contrast to recombinant factor X wild-type, it normalized the bleeding time and the loss of hemoglobin. No sign of thrombogenicity was observed and the generation of activated factor X was controlled by the anticoagulation pathway in all performed coagulation assays. This data indicates that Actiten may be considered as a possible non replacement factor to treat hemophilia's with the advantage of being a zymogen correcting bleedings only when needed.

In Vitro Thrombogenicity Tests of Factor IX Concentrates

1979 ◽  
Vol 42 (05) ◽  
pp. 1355-1367 ◽  
Author(s):  
C V Prowse ◽  
A Chirnside ◽  
R A Elton
Keyword(s):  
Factor Viii ◽  
Partial Thromboplastin Time ◽  
Generation Time ◽  
Activated Partial Thromboplastin Time ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Factor Viii Inhibitor ◽  
Factor Ixa ◽  
Viii Inhibitor

SummaryVarious factor IX concentrates have been examined in a number of in vitro tests of thrombogenicity. The results suggest that some tests are superfluous as in concentrates with activity in any of these tests activation is revealed by a combination of the non-activated partial thromboplastin time, the thrombin (or Xa) generation time and factor VIII inhibitor bypassing activity tests. Assay of individual coagulant enzymes revealed that most concentrates contained more factor IXa than Xa. However only a small number of concentrates, chiefly those that had been purposefully activated, contained appreciable amounts of either enzyme.

scholarly journals Platelet Alterations Caused by Antiplatelet Antibodies in the Circulation

1977 ◽  
Author(s):  
T. Nagasawa ◽  
B.K. Kim ◽  
M.G. Baldini
Keyword(s):  
Platelet Count ◽  
Specific Activity ◽  
Rabbit Model ◽  
Antiplatelet Antibodies ◽  
Large Numbers ◽  
Severe Reduction ◽  
Series Of Experiments ◽  
Specific Activities

It is known that antiplatelet antibodies cause loss of platelet cytoplasmic and granular contents in vitro. It is, however, unknown whether similar platelet changes occur in vivo, in the circulation, leading to destruction and phagocytosis of platelets in the R.E. system. To study this possibility a rabbit model was devised. Severe and stable thrombocytopenia was first produced in rabbits by one intravenous injection of Adriamycin. Large numbers of allogenic platelets labeled in vitro with 51Cr and 14C-serotonin were then infused to raise the circulating platelet count to 180-250 × 103/mm3. A dilute heteroimmune antiplatelet serum prepared in the guinea pig was infused intravenously and platelet samples were collected four times during the subsequent 30 minutes to 24 hours. Platelet hexokinase and β-glucuronidase, 14C-serotonin and 51Cr were measured. Within the first 60 min the specific activity of 51Cr in platelets decreased by 21%, 14C-serotonin declined by 30%, hexokinase by 5% and β-glucuronidase by 29%. During the subsequent 24 hours only 51Cr and hexokinase registered a mild decrease but 51C-serotonin and β-glucuronidase remained essentially unchanged. In a second series of experiments the effect of platelet alloantibodies was studied in rabbits previously immunized with allogenic platelets. The decline in the specific activities of the enzymes and 14C-serotonin was similar to that observed in animals treated with heteroimmune sera but loss of 51Cr was more severe. These results demonstrate that the platelets remaining in the circulation after the disappearance of the immediate effect of hetero- or alloantibodies were qualitatively altered with a severe reduction of their granular and cytoplasmic contents.

In Vitro and In Vivo Efficacy of the Triazole TAK-187 against Cryptococcus neoformans

1998 ◽  
Vol 42 (10) ◽  
pp. 2630-2632 ◽  
Author(s):  
Wiley A. Schell ◽  
Gisele Madeira Duboc De Almeida ◽  
Richard K. Dodge ◽  
Kenji Okonogi ◽  
John R. Perfect
Keyword(s):  
Cerebrospinal Fluid ◽  
Cryptococcus Neoformans ◽  
Cryptococcal Meningitis ◽  
Rabbit Model ◽  
Intermittent Therapy ◽  
In Vitro Activity ◽  
Fluconazole Resistance ◽  
In Vivo Efficacy

ABSTRACT Multiple isolates of Cryptococcus neoformans, including those with fluconazole resistance, were tested to assess the in vitro activity of the new triazole TAK-187. MICs of TAK-187 were at least eightfold lower than those of fluconazole, and fungicidal concentrations for most isolates were 4 μg/ml or less. TAK-187 also was evaluated as intermittent therapy using two dosages in a rabbit model of experimental cryptococcal meningitis. Compared to daily treatment with fluconazole, as little as two doses of TAK-187 given 7 days apart were found to be effective. Plasma and cerebrospinal fluid TAK-187 concentrations were many times higher than MICs and fungicidal concentrations. Based upon its therapeutic efficacy and long half-life in the rabbit model, TAK-187 should be investigated for intermittent dosing in treatment or suppression of cryptococcal infections in humans.

scholarly journals A Single Chain Variant of Factor VIII Fc Fusion Protein Retains Normal In Vivo Efficacy but Exhibits Altered In Vitro Activity

PLoS ONE ◽  
2014 ◽  
Vol 9 (11) ◽  
pp. e113600 ◽  
Author(s):  
Yang Buyue ◽  
Tongyao Liu ◽  
John D. Kulman ◽  
Garabet G. Toby ◽  
George D. Kamphaus ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Factor Viii ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Single Chain ◽  
In Vivo Efficacy ◽  
Fc Fusion Protein ◽  
Chain Variant

scholarly journals Experimental Hemostasis in Normal Dogs and Dogs with Congenital Disorders of Blood Coagulation

Blood ◽  
1967 ◽  
Vol 30 (5) ◽  
pp. 636-668 ◽  
Author(s):  
T. HOVIG ◽  
H. C. ROWSELL ◽  
W. J. DODDS ◽  
L. JØRGENSEN ◽  
J. F. MUSTARD
Keyword(s):  
Factor Viii ◽  
Blood Coagulation ◽  
Bleeding Time ◽  
Light And Electron Microscopy ◽  
Factor Ix ◽  
Surrounding Tissue ◽  
Factor Vii ◽  
Congenital Defects

Abstract Hemostasis was examined after transection of vessels, 50-200 microns in diameter, both in normal dogs and in dogs with congenital defects of either factor VII, factor IX, or factor VIII. The formation of the hemostatic platelet plugs was observed by direct microscopy in vivo, and sections of the plugs were prepared for both light and electron microscopy 10 to 30 minutes after transection. Furthermore, the reaction of platelets from normal and abnormal dogs with adenosine diphosphate, collagen and thrombin was tested in vitro by a turbidimetric technic. In normal and factor VII deficient dogs the initial arrest of bleeding took place about 3 minutes after transection, and rebleeding was infrequently observed. Their platelet plugs were composed of densely packed platelets, anchored to the vascular and perivascular tissue and surrounded by a cap of fibrin. In factor IX deficient dogs there was no definite prolongation of the initial bleeding time, but rebleedings were frequent. In factor VIII deficient dogs the initial bleeding time was prolonged and the intensity of the bleeding had a wave-like characteristic. The plugs in the hemophilic dogs were larger than normal, were rich in channels, and had areas of loosely packed platelets and an incomplete fibrin cap. Treatment of factor IX deficient dogs with Dicumarol did not further impair hemostatic plug formation in the doses used. Treatment of factor VII deficient dogs with heparin, or factor IX deficient dogs with phenylbutazone, prolonged the bleeding time markedly, delayed the building up of the plug, and gave fragile, loosely packed plugs. Treatment of normal dogs with phenylbutazone did not alter the hemostatic process at the dosage used. In the in vitro studies, platelets from the dogs with congenital coagulation defects reacted normally with the aggregating stimuli. It is concluded that the initial platelet interaction wih the vessel wall and surrounding tissue is not dependent upon blood coagulation. An intact intrinsic pathway of coagulation is necessary for the stabilization of the hemostatic plug after it is formed.

The Influence of Infusions of 1-Desamino-8-D-Arginine vasopressin (DDAVP) In Vivo on the Anticoaguhht Effect of Recombinant Hirudin (CGP39393) In Vitro

1991 ◽  
Vol 65 (01) ◽  
pp. 064-066 ◽  
Author(s):  
S H Ibbotson ◽  
P J Grant ◽  
R Kerry ◽  
V S Findlay ◽  
C R M Prentice
Keyword(s):  
Factor Viii ◽  
Arginine Vasopressin ◽  
Potent Inhibitor ◽  
Antithrombotic Agent ◽  
Recombinant Hirudin ◽  
Blood Samples ◽  
Normal Volunteers ◽  
Coagulation Defect

SummaryHirudin is a specific, potent inhibitor of thrombin that may be a valuable antithrombotic agent. The aim of this study was to investigate the hypothesis that the haemostatic effects of DDAVP counteract the coagulation defect induced by hirudin. The effect of DDAVP was studied in vivo on the anticoagulant action of recombinant hirudin (CGP39393) in vitro. Blood samples were taken at intervals from 10 normal volunteers infused with DDAVP. Factor VIII: C rose from (mean) 0.68 IU/ml before DDAVP to 2.L9 and 2.16 IU/ml after 30 and 60 min infusion, respectively. Samples taken during DDAVP infusion showed a dose related decrease in the hirudin (0.5 and 1.0 αM) induced prolongation of the APTT that occurred at FVIII: C concentrations of up to twice normal. At higher concentrations of hirudin no effect on the APTT occurred. These results demonstrate that DDAVP infusion elevates factor VIII: C levels with an associated significant reduction in the anticoagulant effect of hirudin in vitro.

Heated Lyophilized Factor VIII And Factor IX Concentrate Preliminary In Vitro Studies

1981 ◽  
Author(s):  
A Rubinstein
Keyword(s):  
Factor Viii ◽  
Hepatitis Virus ◽  
Heating Time ◽  
Significant Loss ◽  
Factor Ix ◽  
Factor Viii Activity ◽  
Viii And Ix ◽  
Plasma Protein Fraction

It has been known that albumin and plasma protein fraction (PPF) do not transmit hepatitis since these products are heated at 60°C for 10 hours. This heating is sufficient for inactivation of hepatitis virus. It has been previously tried to heat the Cohn Fractions leading to Factor VIII and Factor IX Concentrates in solution, however, this has resulted in significant loss of Factors VIII and IX.We have taken lyophilized Factor VIII Concentrate powder and heated it in a waterbath at 60°C for 10 hours and have demonstrated no significant change in in vitro recovery of Factor VIII activity four hours following the heating. The same was shown for recovery of Factor IX activity after heating lyophilized Factor IX concentrate for 10 hours at 60°C. In addition Factor IX activity was not destroyed following heating of the lyophilized powder for 20-30 minutes at 100°C. This is significant because now potentially this heated lyophilized powder of Factor VIII and Factor IX is free of previous risk of transmission of hepatitis. However, the effect of heating on the thrombogenic effects in vivo of the concentrates and complications was not assessed in this study. Chimpanzee studies are planned to determine whether the heating has inactivated the hepatitis virus.It is possible that a longer heating time will be needed to sufficiently inactivate the hepatitis virus in the lyophilized state.

scholarly journals In vitro and in vivo efficacies of the azole SCH56592 against Cryptococcus neoformans.

1996 ◽  
Vol 40 (8) ◽  
pp. 1910-1913 ◽  
Author(s):  
J R Perfect ◽  
G M Cox ◽  
R K Dodge ◽  
W A Schell
Keyword(s):  
Central Nervous System ◽  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Central Nervous System Infection ◽  
Rabbit Model ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Drug Concentrations

Multiple isolates of Cryptococcus neoformans were tested to compare the in vitro activity of a new triazole, SCH56592, with those of amphotericin B, fluconazole, and itraconazole, MICs of each drug were determined, and minimum fungicidal concentrations of SCH56592 and amphotericin B were measured. MICs of SCH56592 were lower than those of amphotericin B and fluconazole but not those of itraconazole. Minimum fungicidal concentrations of SCH56592 were lower than those of amphotericin B. SCH56592 in the presence of human serum produces an in vitro fungicidal effect for Cryptococcus neoformans. The data indicate that SCH56592 might exert fungicidal as well as inhibitory properties in vivo. On the basis of these results, SCH56592 was evaluated with a rabbit model of experimental cryptococcal meningitis; SCH56592 treatment was compared with treatment with fluconazole. Despite no detectable drug concentrations in the cerebrospinal fluid, the activity of SCH56592 against C. neoformans infection was equivalent to that of fluconazole. SCH56592 has potent in vitro activity against C. neoformans and compares favorably to treatment with fluconazole for a central nervous system infection. SCH56592 should be studied for use in humans with cryptococcal infections.

In Vivo Evidence of Modulation of the Hemophilia Phenotype by the Factor V Leiden.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 693-693
Author(s):  
Alexander Schlachterman ◽  
Jianhua Liu ◽  
Yi-Lin Liu ◽  
Katherine High ◽  
Valder Arruda
Keyword(s):  
Factor Viii ◽  
Thrombus Formation ◽  
Factor V Leiden ◽  
Factor Ix ◽  
Platelet Glycoprotein ◽  
Factor V ◽  
Severe Hemophilia ◽  
Fvl Mutation

Abstract The amelioration of hemophilia phenotype or delayed onset of the bleeding episodes in subjects with severe hemophilia A (FVIII deficiency) has been associated with inherited resistance to activated protein C due to factor V Leiden (R506Q), FVL. These observations were confirmed by in vitro systems in which homozygous phenotype of FVL increased thrombin formation in presence of < 1% FVIII by nearly 5-fold (Blood 90:3067). Here we provide in vivo evidence of the beneficial interaction of FVL on the hemophilia phenotype in mice. Animals with severe deficiency of factor VIII due to deletion of intron 16 of factor VIII gene (HA) or large gene deletion of factor IX (HB) were crossed with FVL homozygous mice [+/+] on C57Bl6 strain [Cui et al. (Blood 96:4222)] We used a modified activated partial thromboplastin time (aPTT) assay to compared clotting times among male HA (n=30), HA/FVL [+/+] (n=7), FVL [+/+] (n=5), and litermate WT mice (n=6) with age ranging from 6–12 weeks. Blood samples were collected by tail vein transection into 3.8% sodium citrate. Values for the aPTT in male HA were 67.3 ± 4 sec, and among WT or FVL [+/+] values were 37 ± 4 sec or 31± 2 sec, respectively. Whereas intermediate aPTT values of 53 ± 3.7 sec were determined in HA/FVL [+/+], which differs from HA mice (p<0.0001) but also from WT or FVL (p<0.0001). A similar shortening of aPTT was also determined among HB/FVL[+/+] which were compared to HB, 55 ± 7 sec vs. 64 ± 0.9. Hemostatic challenge by tail clipping assay failed to revealed differences in bleeding times/blood loss among hemophilia animals with or without FVL mutation. To test whether a more sensitive technique would provide further evidence of the improved hemostasis in HA/FVL mice, we assessed real-time in vivo thrombus formation by confocal and widefield microscopy. Mice were anesthetized and the cremaster muscle was exposed for intravital microscopy. Infusion of fluorescently labeled antibody to murine platelet glycoprotein IIb/IIIa complex via the jugular vein allowed monitoring of platelet deposition upon laser-mediated endothelial injury at several sites of the arterial vessel wall. No thrombus formation was observed in severe HA mice following successive vascular injuries, a finding also common in severe HB mice. However, infusion of factor VIII concentrated clearly induced the thrombi formation upon vascular injury. HA/FVL mice tested presented thrombus formation in a comparable fashion of HA-FVIII transfused mice. These in vivo data provide support to the hypothesis that the FVL mutation has the potential to improve the phenotype of severe hemophilia and may offer a novel therapeutic target for hemophilia.

Sign in / Sign up

Export Citation Format

Share Document