Further Evidence for a Humoral Control of Factor VIII Plasma Levels

1973 ◽  
Vol 30 (03) ◽  
pp. 460-470
Author(s):  
Ricardo H. Landaburu ◽  
Delicia E. Castellanos
Keyword(s):  
Factor Viii ◽  
Adrenal Cortex ◽  
Plasma Levels ◽  
Adrenergic Stimulation ◽  
Negative Results ◽  
Plasma Factor ◽  
Humoral Control ◽  
Acth Release

SummaryFactor VIII increase after stress or adrenergic stimulation appears to be justified by ACTH release, which in turn liberates a principle other than steroids, from the adrenal cortex. A substance isolated from adrenal cortex and denominated S3 increase, when injected, the level of plasma factor VIII. The rise in factor VIII after S3 also occurs in adrenalectomized animals where ACTH or catecholamines administration gives negative results.

scholarly journals Effect of danazol on clotting factor levels, bleeding incidence, factor infusion requirements, and immune parameters in hemophilia

Blood ◽  
1986 ◽  
Vol 68 (3) ◽  
pp. 673-679 ◽  
Author(s):  
P Saidi ◽  
BZ Lega ◽  
HC Kim ◽  
K Jr Raska
Keyword(s):  
Factor Viii ◽  
Plasma Levels ◽  
Fibrinolytic Activity ◽  
Clotting Factor ◽  
Clotting Factors ◽  
Double Blind ◽  
Immune Parameters ◽  
Plasma Factor ◽  
Viii And Ix ◽  
Mucosal Bleeding

Abstract Several recent studies have reported conflicting results on the effectiveness of danazol, an attenuated androgen, in raising plasma levels of clotting factors VIII and IX in patients with hemophilia. We undertook a randomized, double-blind cross-over trial using 8 weeks' administration of danazol (D), 600 mg/d, and 8 weeks' administration of placebo (P) separated by 2 weeks of rest in 12 patients with hemophilia A and four patients with hemophilia B. Plasma factor VIII and IX levels, frequency and type of bleeding episodes, amount of factor concentrate infused, fibrinogen, fibrinolysis assays, antithrombin III, liver function, and immune parameters were followed. During the danazol phase a minimal increase was noted in the average clotting factor levels, an increase that, although statistically significant, was of hemostatically marginal magnitude. Significant increases in protein C and plasminogen levels, however, were observed during the danazol period, suggestive of danazol-mediated enhanced fibrinolysis. Clinically, bleeding frequency was significantly increased, and more clotting factor was consumed during the danazol period. Furthermore, eight episodes of hematuria and oral mucosal bleeding was reported during the danazol phase in contrast to only one episode of hematuria during the placebo phase, consistent with an enhancement of fibrinolytic activity with danazol. We conclude that danazol does not have a hemostatically significant effect on plasma levels of factor VIII and IX but may be associated with enhancement of fibrinolytic activity, resulting in increased bleeding frequency and requiring more clotting factor infusions. Therefore, danazol is not a viable alternative in the treatment of hemophilia.

scholarly journals Effect of danazol on clotting factor levels, bleeding incidence, factor infusion requirements, and immune parameters in hemophilia

Blood ◽  
1986 ◽  
Vol 68 (3) ◽  
pp. 673-679
Author(s):  
P Saidi ◽  
BZ Lega ◽  
HC Kim ◽  
K Jr Raska
Keyword(s):  
Factor Viii ◽  
Plasma Levels ◽  
Fibrinolytic Activity ◽  
Clotting Factor ◽  
Clotting Factors ◽  
Double Blind ◽  
Immune Parameters ◽  
Plasma Factor ◽  
Viii And Ix ◽  
Mucosal Bleeding

Several recent studies have reported conflicting results on the effectiveness of danazol, an attenuated androgen, in raising plasma levels of clotting factors VIII and IX in patients with hemophilia. We undertook a randomized, double-blind cross-over trial using 8 weeks' administration of danazol (D), 600 mg/d, and 8 weeks' administration of placebo (P) separated by 2 weeks of rest in 12 patients with hemophilia A and four patients with hemophilia B. Plasma factor VIII and IX levels, frequency and type of bleeding episodes, amount of factor concentrate infused, fibrinogen, fibrinolysis assays, antithrombin III, liver function, and immune parameters were followed. During the danazol phase a minimal increase was noted in the average clotting factor levels, an increase that, although statistically significant, was of hemostatically marginal magnitude. Significant increases in protein C and plasminogen levels, however, were observed during the danazol period, suggestive of danazol-mediated enhanced fibrinolysis. Clinically, bleeding frequency was significantly increased, and more clotting factor was consumed during the danazol period. Furthermore, eight episodes of hematuria and oral mucosal bleeding was reported during the danazol phase in contrast to only one episode of hematuria during the placebo phase, consistent with an enhancement of fibrinolytic activity with danazol. We conclude that danazol does not have a hemostatically significant effect on plasma levels of factor VIII and IX but may be associated with enhancement of fibrinolytic activity, resulting in increased bleeding frequency and requiring more clotting factor infusions. Therefore, danazol is not a viable alternative in the treatment of hemophilia.

Studies on the Characterization of Factor VIII and a Co-factor VIII

1974 ◽  
Vol 31 (02) ◽  
pp. 328-338
Author(s):  
M. M. P Paulssen ◽  
H. L. M. A Vandenbussche-Scheffers ◽  
P. B Spaan ◽  
T de Jong ◽  
M. C Planje
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
The Body ◽  
Haemophilia A ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Polysaccharide Content ◽  
Plasma Factor ◽  
Two Factors

SummaryFactor VIII occurs in the body in two different forms. In lymph factor VIII is bound to chylomicra. In plasma, factor VIII is bound to a protein.After delipidation of chylomicra we obtained a glycoprotein with a high polysaccharide content and a molecular weight of approx. 160,000.In plasma, factor VIII is attached to a protein which is present in normal concentrations in plasma of patients with haemophilia A and in serum (co-factor VIII).This factor is deficient in both the plasma and the serum of patients with von Willebrand’s disease.The binding between factor VIII and co-factor VIII is reversible.Some properties of these two factors are described.

The Fractionation Properties of Human Factor VIII (Antihaemophilic Factor)

1960 ◽  
Vol 04 (02) ◽  
pp. 253-260 ◽  
Author(s):  
Franco Gobbi
Keyword(s):  
Factor Viii ◽  
Human Factor ◽  
Maximum Yield ◽  
Factor Vii ◽  
Precipitation Method ◽  
Salting Out ◽  
Human Factor Viii ◽  
Plasma Factor ◽  
Two Factors ◽  
Thromboplastic Activity

SummaryThe fractionation properties of human Factor VIII (antihaemophilic factor, AHF, antihaemophilic globulin) have been studied using a plasma of congenital afibrinogenaemia as a starting material.From a fibrinogen-free plasma, Factor VIII does not precipitate with ethanol at a final concentration of 8%; on the contrary the maximum yield is reached at an ethanol concentration of 25%.With a precipitation method carried out by a one to ten dilution of plasma with distilled water and acidification by N/10 hydrochloric acid to a pFI 5.2, Factor VIII does not precipitate with the euglobulin fraction; when normal plasma is used, such a precipitation is almost complete.With the salting-out fractionation method by ammonium sulphate, Factor VIII precipitates at a concentration between 25 and 33% of saturation either from fibrinogen-free and from normal human plasma.A non-specific thromboplastic activity appears in the fractions prepared by every method. This activity, which is probably due to the activation of seric accelerators, is easily removed by Al(OH)s adsorption. Thus, in order to insure the specificity of Factor VIII assays, the preliminary adsorption of the fractions is indispensable before testing their antihaemophilic activity.Fibrinogen and Factor VIII have different and definite precipitation patterns. When these two factors are associated the fractionation properties of AHF appear quite modified, showing a close similarity to those of fibrinogen. This fact can explain the technical difficulties encountered in the attempt to purify the antihaemophilic factor, and the lack of reproducible procedures for removing fibrinogen without affecting Factor VII.

Vampire Bat Salivary Plasminogen Activator Evokes Minimal Bleeding Relative to Tissue-Type Plasminogen Activator as Assessed by a Rabbit Cuticle Bleeding Time Model

1995 ◽  
Vol 73 (03) ◽  
pp. 478-483 ◽  
Author(s):  
Michael J Mellott ◽  
Denise R Ramjit ◽  
Inez I Stabilito ◽  
Timothy R Hare ◽  
Edith T Senderak ◽  
...  
Keyword(s):  
Factor Viii ◽  
Plasminogen Activator ◽  
Intravenous Administration ◽  
Bleeding Time ◽  
Bleeding Risk ◽  
Tissue Type ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator ◽  
Plasma Factor ◽  
Vampire Bat

SummaryCuticle bleeding time (CBT) measurements in anesthetized rabbits were performed to assess the potential bleeding risks which may accompany the administration of tissue-type plasminogen activator (tPA) or vampire bat salivary plasminogen activator (BatPA). The dose of BatPA or tPA used in this study, 42 nmol/kg, was previously shown to be efficacious using a rabbit femoral artery thrombosis model (Gardell et al, Circulation 84:244, 1991). CBT was determined by severing the apex of the nail cuticle and monitoring the time to cessation of blood flow. CBT was minimally elevated (1.6-fold, p<NS) following bolus intravenous administration of BatPA; in contrast, bolus intravenous administration of tPA dramatically elevated CBT (6.2-fold, p<0.05). Rabbits treated with tPA, but not BatPA, displayed profound activation of systemic plasminogen and consequent degradation of Factor VIII and fibrinogen. Elevations in CBT after the administration of tPA were reversed by the replenishment of plasma Factor VIII activity to 40% of control, but were unaffected by complete replenishment of plasma fibrinogen. The results of this study suggest that the administration of BatPA, at a dose that promotes thrombolysis, may evoke a minimal bleeding risk, relative to an equi-efficacious dose of tPA. In addition, the tPA-provoked proteolytic consumption of Factor VIII may be a key contributor to the heightened bleeding risk.

The Basis for the Increase in Factor VIII Procoagulant Activity During Exercise

1983 ◽  
Vol 49 (01) ◽  
pp. 053-057 ◽  
Author(s):  
Robert G Kopitsky ◽  
Mary Ellen P Switzer ◽  
R Sanders Williams ◽  
Patrick A McKee
Keyword(s):  
Factor Viii ◽  
Acute Exercise ◽  
Post Exercise ◽  
Fviii Activity ◽  
Plasma Factor ◽  
The Subject ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Healthy Males ◽  
Related Increase

SummaryWe studied the effect of acute exercise on the ability of thrombin to activate plasma factor VIII (FVIII) activity in 20 healthy males. The subject showed an average exercise-related increase in FVIII activity of 54.5±8.2% over pre-exercise FVIII activity (p<0.001). When exposed to the same concentration of thrombin, post-exercise FVIII activity showed greater enhancement than pre-exercise FVIII activity: 157.1±12.8% increase in activity versus 117.3±9.9%, respectively (p<0.01). The degree of the potentiated thrombin effect in post-exercise samples relative to pre-exercise samples was linearly correlated with the degree of the exercise-related increase in FVIII activity. Taken together with our previous observations that the extent of thrombin enhancement of FVIII activity varies inversely with the mole ratio of FVIII/von Willebrand factor subunits to thrombin, these findings imply that release of FVIII does not occur during exercise, and that the exercise-related increase in FVIII activity results primarily, if not completely, from activation of already circulating but inactive FVIII.

scholarly journals Human megakaryocytes. II. Expression of platelet proteins in early marrow megakaryocytes.

1981 ◽  
Vol 154 (1) ◽  
pp. 88-100 ◽  
Author(s):  
E M Rabellino ◽  
R B Levene ◽  
L L Leung ◽  
R L Nachman
Keyword(s):  
Factor Viii ◽  
Fc Receptors ◽  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Ia Antigen ◽  
Plasma Factor ◽  
Factor Viii Antigen ◽  
Megakaryocyte Differentiation ◽  
Marrow Cells ◽  
Platelet Proteins

Analysis of various platelet proteins by immunofluorescence demonstrated that platelet glycoproteins Ib, IIb, and IIIa, as well as plasma factor VIII antigen (factor VIII:AGN), platelet factor 4, and fibronectin are present in the vast majority of morphologically recognizable megakaryocytes. In addition, a small number of lymphoid-like mononuclear marrow cells, representing approximately 1.4--2.9/10(4) marrow cells, was found to express the same platelet proteins. This population of early marrow megakaryocytes is analogous to small acetylcholinesterase-positive rat and mouse marrow cells. Fc receptors for IgG were expressed in all megakaryocytes and megakaryocyte precursors, whereas the Ia antigen was detected only on a proportion of mature megakaryocytes and not on only early or precursor megakaryocytes. Platelet glycoproteins Ib, IIb, and IIIa, as well as factor VIII:AGN, and platelet factor 4 were established as distinct markers for marrow megakaryocytes and may be helpful for identifying megakaryocytic cells as well as for monitoring events of megakaryocyte differentiation.

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