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Biomedical subjects

C V Prowse

Publications and source records attributed to C V Prowse.

86 records · Page 5Linked to original sources
PubMed1980

In vitro thrombogenicity tests of factor IX concentrates. II: effects of phospholipids and heparin.

Measurement of the total phospholipid (and that portion active in coagulation) in factor IX concentrates revealed no correlation with in vitro tests of potential thrombogenicity, except in the case of the recalcification time and the thrombin generation test which may detect coagulant phospholipid as well as the presence of thrombogenic enzymes. This is probably due to separation of the prothrombin complex proteins from most phospholipid during ion-exchange chromatography. Although low levels of phospholipid remain in the final product these are apparently insufficient to effect appreciable activation of factor IX concentrates despite low levels of antithrombin III. Two tests which measure the formation of thrombin and factor Xa after recalcification of concentrates were affected by the addition of exogenous phospholipid. However this is a relative effect such that differences are quantitative rather than qualitative. Heparin addition during production of factor IX concentrate was found to have only minor effects on the results of in vitro thrombogenicity tests of the final product. This was confirmed in the laboratory by incubation of unheparinised products with heparin for periods of up to 6 hr.

Blood Coagulation Tests↗
PubMed1980

Plasma beta-thromboglobulin in diabetes mellitus.

Plasma beta-thromboglobulin was measured, using the Edinburgh radioimmunoassay technique and anticoagulant mixture (containing prostaglandin E1) in 61 normal subjects, 67 diabetics with and 54 diabetics without microangiopathic complications. Plasma beta-thromboglobulin was significantly higher in the diabetic patients (p < 0.01) but there was no significant difference between the two diabetic groups. Twenty-six normal subjects, 27 diabetics with and 39 diabetics without complications were studied further by measuring beta-thromboglobulin in four different ways using two different radioimmunoassay techniques and two anticoagulant mixtures (with and without prostaglandin E1). The Edinburgh assay gave a value 1.97 times that obtained with the Amersham assay, and the Edinburgh anticoagulant a value 0.78 times that with the Amersham anticoagulant. Beta-thromboglobulin concentration in the meniscus layer was approximately twice that in the middle layer. The lower beta-thromboglobulin values obtained with the Edinburgh anticoagulant may result from a different sampling technique or from prevention of in vitro beta-thromboglobulin release, after venepuncture, by prostaglandin E1. Abnormal platelet behaviour in diabetes was confirmed although its role in the pathogenesis of microangiopathic complications remains unclear.

Adult↗
PubMed1980

Effect of different resuspension media on the post-thaw characteristics of frozen blood.

Red blood cells frozen by the low-glycerol fast-freezing technique were thawed, deglycerolized and resuspended in various media. The use of ACD-saline for resuspension markedly reduced in vitro haemolysis such that the red cells could be transfused up to 5 d after thawing. At this time the cells contained satisfactory levels of potassium and organic phosphates, while bacterial contamination was negligible. For the past 4 years we have operated a small bank of previously frozen red blood cells which were thawed and resuspended in this way. Over 3500 units have been transfused after 1--5 d post-thaw storage without untoward effects.

Anticoagulants↗
PubMed1980

Haemostatic effects of lysine vasopressin and triglycyl lysine vasopressin infusion in patients with cirrhosis.

Eight patients with cirrhosis were infused with lysine vasopressin (10 microgram LVP) and triglyclylysine vasopressin (750 microgram and 2000 microgram Glypressin, GVP) on separate occasions. LVP infusion resulted in an increase in factor VIII, factor VIII-related antigen and plasminogen activator (PA). The factor VIII antigen: activity ratio decreased following infusion, but factor VIII electrophoretic mobility and in vitro decay rate were unchanged. GVP infusion produced no change in factor VIII or PA. Assay of vasopressin-like antigen and antidiuretic activity showed that GVP is cleaved to LVP in vivo. The low levels of LVP formed by this reaction might explain the prolonged vasometer effects of GVP, as well as its inability to cause release of factor VIII or PA. Compared to LVP, GVP has a longer pressor effect in vivo, has no effect on fibronolysis and exhibits no cardiotoxic effects and may therefore be the treatment of choice in bleeding oesophageal varices.

Antigens↗
PubMed1979

Specificity in the factor VIII response to vasopressin infusion in man.

Structural requirements of the systemic factor VIII response to intravenous vasopressin in man has been investigated using vasopressin analogues. With the analogues available the receptor specificity of this phenomenon could not be distinguished from those associated with the previously described plasminogen activator release or antidiuretic effects of this hormone. Further studies using 1-desamino-[8-D-arginine]vasopressin showed a dose-related release of both procoagulant and antigenic components of the factor VIII complex. The newly released factor VIII could not be distinguished from circulating factor VIII on the basis of molecular size, electrophoretic mobility or in vitro stability despite apparent differences in the duration of response of the procoagulant and antigenic components in vivo.

Adult↗
PubMed1979

Evaluation of the 'Mason' (continuous-thaw-siphon) method for cryoprecipitate production.

A comparison was made of the factor VIII recovery in cryoprecipitate made by the continuous-thaw-siphon technique of Mason [1], by our routine method of overnight thawing at 4 degrees C and by a fast-thaw method. The siphon method resulted in a mean recovery of 71% of the factor VIII. This is at least double the yield obtained by the routine method and could not be solely attributed to the faster processing as cryoprecipitate prepared by the fast-thaw method gave a factor VIII yield of 53%, which was significantly less than the Mason product. This product also contained increased amounts of factor VIII-related antigen and fibrinogen. Characterisation of the thaw-siphon cryoprecipitate factor VII by gel filtration, electrophoretic mobility, stability and measurement of isoagglutinin titre did not reveal any significant qualitative differences from cryoprecipitate produced by other methods.

Antigens↗
PubMed1979

Effects of lysine vasopressin and glypressin on the fibrinolytic system in cirrhosis.

In eight patients with cirrhosis of the liver and portal hypertension an intravenous infusion of lysine vasopressin induced a rapid increase in the plasma level of the fibrinolytic proenzyme plasminogen activator. In contrast, triglycyl lysine vasopressin (glypressin; GVP), in a dose known to lower portal venous pressure, produced no fibrinolytic response. This lack of fibrinolytic response represents an advantage of GVP over lysine vasopressin in addition to its longer in vivo half-life and lower cardiotoxicity. Clinical trials of GVP in the treatment of bleeding oesophageal varices are needed.

Aged↗
PubMed1977

The gamma-carboxy glutamic acid content of human and bovine prothrombin following warfarin treatment.

A form of prothrombin induced by Warfarin therapy, has been isolated which is adsorbed onto insoluble barium salts, but has a reduced biological activity. This protein contains, on average, seven out of a possible ten gamma-carboxy glutamic acid residues. A second form of prothrombin is also described, which is not adsorbed into barium slats, and has less than 1% the activity of the normal protein, contains only four gamma-carboxy glutamic acid residues. The significance of these results is discussed.

Amino Acid Sequence↗
PubMed1976

A variant of prothrombin induced in cattle by prolonged administration of warfarin.

Cows on long term Warfarin therapy produce a form of prothrombin which, although it binds to barium citrate, has a low biological activity. Activation experiments on this form of prothrombin show that it is only slowly converted to thrombin in the presence of Ca2+, although the thrombin produced has normal activity. Further experiments show that the Fragment 1 region of the molecule has a reduced calcium binding capacity. The results indicate the existance of a partially carboxylated form of prothrombin.

Animals↗
PubMedDate not supplied

Thrombogenicity of a factor IX concentrate quantitated in a canine model.

Dose-ranging studies with a batch of factor IX concentrate have been performed in a canine non-stasis model of thrombogenicity. Doses between 50 and 200 IU/kg were infused over a 30 min period, and beagles were found to be more sensitive than greyhounds with regard to subsequent alterations in haemostatic parameters over a 150 min period. In beagles we detected significant increases in plasma fibrin(ogen) degradation products and reduction in fibrinogen concentrations in a dose-related manner after infusion of factor IX concentrate over the range 50-150 IU/kg. Plasma fibrinopeptide A was the most sensitive marker of activation of coagulation with significantly increased levels after factor IX at 50 IU/kg compared with control infusions of albumin. Recovery of infused factor IX was similar to values reported in man. In these experiments, measurement of urinary fibrinopeptide A did not prove to be a useful indicator of thrombogenicity. In conclusion, the beagle non-stasis model will provide a sensitive method to quantify the unwanted thrombogenic activities associated with the use of high doses of certain factor IX concentrates.

Animals↗