Jerry Koutts

Variant patterns in von Willebrand's Disease

Abstract Investigation of a group of patients with classical von Willebrands disease by the additional techniques of ristocetin induced platelet aggregation and quantitative immunoelectrophoresis for factor VIII related antigen, indicate that there is considerable heterogeneity in this condition. On the basis of the results presented, it appears that there could be at least five separate subpatterns in von Willebrands disease. At present this condition should not be considered a single disease entity, but a syndrome with features which may be the common expression of a number of separate genetic disturbances.

Circulating platelet aggregates in ischaemic heart disease and their correlation to platelet life span

Abstract The platelet survival time and the presence of circulating platelet aggregates have been studied in patients with ischaemic heart disease (IHD). Platelet aggregates were detected in patients with recent myocardial infarcts and not in patients with asymptomatic ischaemic heart disease. A highly significant correlation was found between the presence of circulating platelet aggregates and the shortening in platelet survival. The significance of these findings on the overall prognosis is as yet uncertain but the recognition of two groups of patients with or without aggregates could influence the choice and effectiveness of antiplatelet therapy.

The dynamic inter-relationship between factor VIII and von Willebrand factor.

Abstract A monospecific heterologous antibody which specifically inhibited von Willebrand factor (W.F.) but had no factor VIII procoagulant (VIIIc) neutralising properties was insolubilised by attachement to sepharose beads. When fresh normal plasma was mixed with such beads, VIIIc, W.F. and factor VIII related antigen (VIIIAg) were removed in equal proportions, with the VIIIc lost from the plasma being detectable attached to the sepharose. This VIIIc was removed from the sepharose and largely recovered in the eluate after treatment with 0.2M calcium chloride. Subsequent addition of plasma resulted in a high transfer of VIIIc from the plasma onto the sepharose beads without accompanying W.F. and VIIIAg. Similar experiments, with initial treatment of antibody attached sepharose beads with serum, resulted in no independent segregation of VIIIc on subsequent addition of plasma. It is suggested that VIIIc and W.F. exist in plasma as separate, but attached molecules in a dynamic equilibrium. In serum, W.F. loses its ability to attach VIIIc.

Simplified immunoradiometric assay for factor VIII coagulant antigen

A simplified, non‐competitive, solid phase immunoradiometric assay has been developed for the quantitation of factor VIII coagulant antigen (VIII:CAg)—the antigenic counterpart of FVIII coagulant activity (VIII:C). Both homologous and heterologous antibodies to human factor VIII (FVIII) were used in this assay. Initially, FVIII in a test sample was attached to immobilized, human IgG obtained from a polytransfused haemophilia A patient with a high titre antibody to VIII:C. The bound FVIII was then detected using rabbit 125I‐IgG specific for human FVIII. The concentration of VIII:CAg correlated well with VIII:C levels in the plasma from normal donors (r= 0.84, n= 15).

The aggregation of human platelets by ascitic fluid. a mechanism for the disseminated intravascular coagulation (DIC) complicating leveen shunts

Disseminated intravascular coagulation (DIC) is a common problem in patients with LeVeen shunts. There is little doubt that this is caused by the infusion of ascitic fluid into the systemic circulation since ligation of the shunt is associated with cessation of DIC and patients who do not develop this complication usually have non-functioning shunts. The factor in the ascitic fluid responsible for the precipitation of DIC has not been previously recognized. This study is concerned with the effects of ascitic fluid on human platelets and offers an explanation for the mechanism of DIC post-LeVeen shunts. The addition of ascitic fluid concentrated 5-fold to platelet rich plasma resulted in marked platelet aggregation which was inhibited by EDTA and adenosine. No aggregation was observed when aspirin treated platelets were used. The aggregating activity could be precipitated by high-speed ultracentrifugation at 100,000xa0g for 60 min. The pre-incubation of the aggregating fluid with collagenase resulted in . complete loss of aggregation. These findings suggested that the aggregating factor was collagen. This was confirmed by a hydroxyproline assay and the finding of a brand corresponding to type I collagen on SDS polyacrylamide gel electrophoresis. Besides its ability to activate platelets, collagen can also activate the contact clotting factors, namely factors XI and XII. This dual activation would result in significant thrombin generation with the development of DIC in vivo . Preliminary experiments in rabbits indicate that the infusion of collagen obtained from ascitic fluid precipitates DIC which is prevented by the prior use of aspirin. The role of aspirin in the prevention or modification of DIC post-LeVeen shunts in man needs to be explored.

Investigation of a coagulation accelerating factor (CAF) in glomerulonephritis.

Summary A coagulation accelerating factor was purified from the plasma of two patients with glomerulonephritis (GN) who suffered from thrombotic complications. The factor co‐purified with factor VIII/von Willebrand factor complex (FVIII/vWf) and under dissociating conditions remained associated with the factor VIII coagulant activity (FVIII). Control purified FVIII/vWf showed no coagulation accelerating activity under the experimental conditions used. The levels of coagulation accelerating factor, FVIII and von Willebrand factor (vWf) were reduced by incubation with rabbit anti‐human FVIII/vWf or human anti‐FVIII serum indicating a close association of these three activities. Multimeric analysis of the plasma FVIII/vWf complex from the two patients demonstrated a reduction in the high molecular weight multimers and the presence of an additional band not present on analysis of normal FVIII/vWf. It is sugggested that the coagulation accelerating factor represents an active form of FVIII which has different in vitro properties to thrombin activated FVIII.