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At least 19 recordsLinked to original sources
PubMed1979

Synthesis of procoagulant factor VIII, factor VIII related antigen and other coagulation factors by the isolated perfused rat liver.

The synthesis of factor VIII and other coagulation factors has been studied using an isolated, perfused rat liver. Synthetic function of the liver was validated by adding [35S]L-methionine to the perfusion medium and performing two-dimensional crossed immunoelectrophoresis and autoradiography on samples obtained during perfusion. Progressive incorporation of radioactivity into plasma proteins was demonstrated. This was inhibited by cycloheximide. Coagulation factor assays demonstrated synthesis of factors II, IX and X and of factor V and procoagulant factor VIII (VIIIC). Synthesis of factor VIII related antigen (VIIIRAg), measured in an immunoradiometric assay, was not significantly demonstrated. Addition of warfarin to the perfusion medium inhibited the synthesis of factors II, IX and X but not of factors V and VIII. Cycloheximide completely inhibited synthesis of all coagulation factors but actinomycin acted only after a latent period. Reticuloendothelial cell blockade was attempted by adding ethionine to the perfusion medium or by administration of Indian ink to the donor animals prior to removal of the livers. In these instances synthesis of factor V and factor VIIIC was inhibited but not that of factors II, IX and X. The results confirmed the functional capacity of the isolated liver for synthesizing proteins and the vitamin K dependent coagulation factors, and suggested similar kinetic features for the synthesis of factors V and VIIIC. Failure to detect significant VIIIRAg synthesis in these experiments is consistent with the hypothesis that this protein is released by vascular endothelial cells throughout the body and is activated or joined to VIIIC or stimulates its production in the liver.

Animals↗
PubMed1978

Factor VIII activity and factor VIII related antigen in newborns.

Factor VIII procoagulant activity and factor VIII related antigen were examined in 20 full-term and preterm newborn infants during the first days of life. The control group involved 15 adults volunteers. Factor VIII activity was estimated by a one-stage test and factor VIII related antigen was determined by immunelectrophoresis according to Laurell, using our own rabbit antiserum. The following results were obtained:--Factor VIII activity during the first 3 days of life did not differ from the normal range of the adult controls.--The concentration of factor VIII related antigen in newborns was markedly higher than in adults on the first, and to a lesser extent on the second, day of life.--The antigen concentration decreases on the second and following days of life to adult levels. The cause of this discrepancy cannot be completely explained but possible reasons are discussed.

Age Factors↗
PubMed1979

Factor VIII procoagulant activity, factor VIII related antigen and von Willebrand factor in newborn cord blood.

The mean level of factor VIII procoagulant acitivity (VIII:C) and factor VIII related antigen (VIIIR:AG) was normal in 100 newborn cord plasmas, whereas that of von Willebrand factor (VIIIR:WF) activity was slightly lower than normal. On crossed immunoelectrophoresis, 20 of 50 newborn infants had an increased anodal mobility of VIIIR:AG. When the cord plasma showing an abnormal electrophoretic pattern was mixed with normal plasma, two precipitation peaks with a broad base were found. Similar mixing experiments with the abnormal cord plasma and plasma from a patient with atypical von Willebrand's disease did not normalize the electrophoretic mobility of VIIIR:AG. Gel filtration of the cord plasma with an abnormal electrophoretic pattern of VIII:AG, showed that the three activities were all detected at the position corresponding to a molecular weight of about 800 000. The results suggest the presence of qualitative abnormalities of the factor VIII molecule in half of full-term newborn cord plasma.

Adult↗
PubMed1977

[Factor VIII activity and factor VIII associated antigen in newborns (author's transl)].

Factor VIII activity and factor VIII associated antigen were determined in healthy term newborns. On the first day of life factor VIII activity was higher than in adults. The activity reached the adult level at about the tenth day. The factor VIII associated antigen was found higher than the activity and did not decrease in the first ten days. Studies of the factor VIII associated antigen of newborns by the two-dimensional immunoelectrophoresis showed the same pattern as compared to adults.

Antigens↗
PubMed1979

Effect of dextran on factor VIII (antihemophilic factor) and platelet function.

Three different properties of factor VIII (antihemophilic globulin) were studied after infusion of 500 ml of six per cent Dextran 70 to healthy volunteers. This dose caused no change in the factor VIII coagulant activity while there was a significant but temporary decrease of factor VIII related antigen. The Ristocetin induced platelet aggregation analysed with native as well as with formalin-fixed platelets, also decreased significantly. The maximal decrease was found a few hours after the infusion. The decrease was seen only if Dextran was infused in vivo and not if Dextran was added to blood in vitro. The dysfunction of factor VIII caused by Dextran resembles that found in one variant of von Willebrand's disease. This finding probably explains the platelet function inhibiting properties of Dextran, and may be of significance for its antithrombotic effects.

Adolescent↗
PubMed1979

Fatal iron intoxication with multiple coagulation defects and degradation of factor VIII and factor XIII.

A severe iron intoxication in a 15-year-old girl resulted in profound damage to vital organs and multiple clotting defects, but no haemorrhagic diathesis. Investigation revealed not only impaired synthesis of coagulation factors but also abnormal proteolysis by plasmin as well as by other proteolytic enzymes liberated from leucocytes and damaged tissue cells affecting especially factor VIII and factor XIII.

Adolescent↗
PubMed1979

Detection of Haemophilia A carriers by replicate factor VIII activity and factor VIII antigenicity determinations.

Factor VIII (fVIII) activity and antigenicity were determined on replicate fresh blood samples drawn on three separate occasions in 48 normal females and 37 obligatory haemophilia A carriers, in an attempt to improve the detection rate. fVIII activity was assayed by a one-stage method and fVIII antigenicity by the Laurell's technique employing an anti-fVIII antiserum prepared in rabbits. The mean results for the individual subjects were analysed after establishing a discriminant function. The probability of being a carrier was determined on the basis of laboratory data and family history. The probability data were translated into more simple terms applicable for genetic counselling by defining three categories: Definite carriers, doubtful carriers and definite normals. Of the obligatory carriers, 83.8% were classified definite carriers, 13.5% doubtful carriers and 2.7% as definite normals. Of the normal females, 4.2% were classified as definite carriers, 18.7% doubtful carriers and 77.1% as definite normals. Adjustment of the results according to age was found unnecessary. The precision of the determinations of fVIII antigenicity and fVIII activity in individual subjects was calculated for different numbers of replicate tests performed in the same individual. It was found that if only one test is performed, a substantial error might occur. Three replicate tests considerably diminish this error, although it is still in the range of +/- 16--29%. For suspected carriers who fall in the doubtful category it is suggested that six or even more tests are performed.

Adolescent↗
PubMed1977

Effects of amidination and chemical cross-linking on human factor VIII (antihemophilic factor).

The bifunctional reagent dimethyl suberimidate, reacting with primary amino groups of proteins, was used to cross-link highly purified human factor VIII. Reaction products were reduced with beta-mercaptoethanol or treated with Rhizopus arrhizus triglyceride lipase. The proportions of the dissociated subunits and their oligomers were calculated from the relative staining intensities of individual bands following polyacrylamide electrophoresis in the presence of sodium dodecyl sulfate. Low concentrations of dimethyl suberimidate (up to 0.5 mM) produced covalently linked dimers which retained full functional (coagulant and von Willebrand factor) activities. Treatment with increasing concentrations of dimethyl suberimidate resulted in an almost simultaneous appearance of both trimeric and tetrameric species, suggesting the existence of specific intra-dimer contacts. A parallel decrease of functional activities was observed at higher concentrations of dimethyl suberimidate. A monofunctional reagent (ethyl acetimidate), reacting similarly with primary amino groups, amidinated factor VIII at rates similar to dimethyl suberimidate. Up to 40% amidinated factor VIII retained full biological activities. We conclude that the most reactive lysine residues are not involved in the active sites responsible for either coagulant or von Willebrand activity.

Blood Coagulation↗
PubMed1978

Severe factor VIII and factor IX deficiency in females.

A survey of 11 hemophilia centers produced data concerning 28 females with extremely low levels of factor VIII or IX coagulant activity. Ten of the 28 have hemophilia A, six have hemophilia B, and 12 have severe von Willebrand's disease. The 16 females who have severe factor VIII or factor IX deficiency as an isolated defect exemplify several of the possible genetic explanations for the occurrence of hemophilia in females. All 16 bruise excessively, and several have had recurrent hemarthroses. Three of these girls, ages five, 10 and 23 years, have evidence of chronic hemophilic arthropathy. The 12 females with severe von Willebrand's disease are either homozygous for von Willebrand's disease or severely affected heterozygotes. All 12 have mucous membrane bleeding. In addition, five of the 12 have recurrent hemarthroses and three have evidence of chronic joint disease. However, the major problem in the adult females with von Willebrand's disease has been extreme menorrhagia. One of the seven adults underwent irradiation sterilization and another had a hysterectomy because of menorrhagia. The others have been managed with anovulatory drugs or plasma infusions and EACA. Despite menorrhagia, five pregnancies and deliveries have been uneventful in three of these women.

Adolescent↗
PubMed1977

Platelet adhesiveness and aggregation in combined factor V and factor VIII deficiency and in combined factor VII and factor VIII deficiency.

Platelet aggregation and adhesiveness were studied in 3 patients with combined factor V and factor VIII deficiency and in 3 patients with combined factor VII and factor VIII deficiency. The first three patients belonged to three different kindreds whereas the second group belonged to the same kindred. Serotonin C14 uptake and release was also found to be normal in these patients. These studies indicate that platelet function is normal in combined defects of factor VIII. These findings were in agreement with the presence of a normal bleeding time and a normal factor VIII antigen level in all these patients.

Blood Coagulation Disorders↗
PubMed1977

Stabilization of factor VIII in plasma by the von Willebrand factor. Studies on posttransfusion and dissociated factor VIII and in patients with von Willebrand's disease.

In normal plasma, the ratio of the procoagulant activity of factor VIII (VIII(AHF)) to that of the von Willebrand factor activity (ristocetin cofactor, VIII(VWF)) or factor VIII antigen (VIII(AGN)) is approximately 1, but ratios > 1 (e.g., VIII(AHF) > VIII(VWF) or VIII(AGN)) may be observed in some patients with von Willebrand's disease and in the "late" posttransfusion plasmas of patients with this disorder. The lability of VIII(AHF) was studied by incubating plasma, diluted 1:10 in imidazole buffer pH 7.1, for 6 h at 37 degrees C. With normal plasmas, 77+/-12% (SD) of the original VIII(AHF) activity remained after incubation. VIII(AHF) was labile (e.g., 35-55% residual activity) in the "late" posttransfusion plasmas (VIII(AHF) >> VIII(VWF)) of a patient with von Willebrand's disease, but not in the "early" posttransfusion plasmas (VIII(AHF) approximately VIII(VWF)). VIII(AHF) was also labile in the (base-line) plasmas of three patients with von Willebrand's disease in whom the ratios of VIII(AHF) to VIII(VWF) were 4.4 to 8.1, but not in the plasmas of four other patients in whom the ratio was approximately 1. The electrophoretic mobility of factor VIII antigen was increased in two of the three patients with labile VIII(AHF). In both of these patients, and in the late posttransfusion plasmas, labile VIII(AHF) activity could be stabilized by the addition of purified von Willebrand factor (lacking VIII(AHF) activity) or by hemophilic plasma, but not by plasmas of patients with severe von Willebrand's disease. Thus, VIII(VWF) may serve to stabilize VIII(AHF) and this might explain the posttransfusion findings in von Willebrand's disease.

Blood Coagulation Factors↗
PubMed1977

Inherited combined deficiency of factor V and factor VIII: report of a case with normal factor VIII antigen and ristocetin-induced platelet aggregation.

A patient with inherited combined deficiency of factor V and factor VIII is reported, who demonstrated normal levels of factor VIII antigen and plasma cofactor for ristocetin-induced platelet aggregation. The relationship of this condition to classical hemophilia and von Willebrand's disease is discussed. The data presented suggest that multiple loci on at least 2 chromosomes are necessary for the normal expression of factor VIII activity.

Adult↗