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We have investigated the influence of dietary n-6/n-3 (ù-6/ù-3) polyunsaturated fatty acid-balance on the tendency to arterial thrombosis and the progress of atherosclerosis in apoE-/- LDLR-/- double knockout mouse. Homozygous apoE-/- LDLR-/- double knockout mouse (DKO mice, 129XC57BL/6J background) and male C57BL/6 mice aged 6 weeks were divided into four groups. Each group was fed a diet containing a different n-6/n-3 ratio (Group l: 0.29; Group 2: 1.43; Group 3: 5.00; Group 4: 8), prepared with high linolenic (LNA) flaxseed oil (n-3 rich) and high linoleic (LA) safflower oil (n-6 rich). There were no statistical differences in the gain in body weight between the four groups. After 16 weeks, plasma triglyceride and LDL levels in Group 1 were significantly lower than in the other groups. Conversely, HDL was the highest. After 8 and 16 weeks, the tendency to arterial thrombosis was assessed using a He-Ne laser-induced thrombosis model. The degree of atherosclerosis was measured using the entire aorta method employing image analysis software. The n-6/n-3 ratio had a dose-dependent antithrombotic effect (thrombus volume decreased 23%, Group 1 vs. Group 4), In addition, the extent of atherosclerosis was less in the animals fed a low n-6/n-3 ratio compared with the high n-6/n-3 ratio group (atherosclerotic area decreased 40%, Group 1 vs. Group 4). The lowest n-6/n-3 ratio tested (0.29) was the most effective in suppressing the thrombotic and atherosclerotic parameters in these DKO mice.

In spite of recent advances in knowledge concerning the detailed biochemistry of blood coagulation, the diagnosis of haemostatic disturbances remains an important problem of clinical judgement in many instances. Laboratory support relies initially on a series of screening tests designed to investigate the general nature of blood clotting. Recent interest in these aspects is centred on standardization and quality assurance of methods and results. Procedures have been recommended in an attempt to unify data. Several aspects of conventional laboratory investigations have been modified and the reliability of diagnostic information has been improved. Some relatively recent findings have extended the application to coagulation studies. For example, the discovery of protein C, a potent physiological inhibitor of blood coagulation, has clarified the nature of the clotting disorder in some patients with hereditary thrombosis disease. In addition, close analysis of plasma from patients with systemic lupus erythematosus has stimulated interest in the association between the haemostatic, neurological and immunological abnormalities recorded in these patients. More recently, sophisticated techniques for the diagnosis of many coagulation factor defects have been developed. Carrier detection of the sex-linked disorders is undertaken widely with reasonable success and reliable prenatal diagnosis procedures have been established in specialized centres. Unequivocal information regarding the diagnosis of carrier status in some families is obtained by the use of gene analysis and linked polymorphisms. Precise details of the genes for several clotting factors have been recorded. Future development in this field is likely to improve the clinical course of many coagulation disorders.

The levels of procoagulant factor VIII activity in the plasma of four patients with von Willebrand's disease (v Wd) obtained 24 hours after treatment with cryoprecipitate or fresh-frozen plasma were higher than those of factor-VIII-related antigen. Analysis of the plasma by gel chromatography on sepharose 60 showed two peaks of factor-VIII procoagulant activity. A lower-molecular weight peak was not seen in normal plasma or that of treated haemophiliacs. In one patient hitherto diagnosed as v Wd an intermediate pattern of results was observed but this patient was otherwise not typical and may have been suffering from a variant of haemophilia or v Wd. In the patients tested the lower-molecular weight procoagulant factor VIII did not precipitate with rabbit antiserum to factor-VIII-related antigen and a plasma sample which contained excess lower-molecular weight procoagulant activity did not neutralise the precipitating capacity of rabbit antiserum. It did however neutralise the procoagulant inhibitory activity of rabbit antiserum and human inhibitor. The findings are consistent with the hypothesis that “factor VIII” consists of a high-molecular weight unit (HMW) and a lower-molecular weight unit (LMW). It is suggested that HMW, autosomally controlled, gives precipitin reactions with the rabbit antisera and stimulates the formation or release of LMW. It is further suggested that LMW, controlled by the X-chromosome, is complexed to or carried by HMW. The evidence indicates that LMW has procoagulant activity alone or when carried by HMW and the appearance of free LMW in treated v Wd supports the proposed hypothesis.

Five different antisera raised against “factor VIII” have been compared with respect to their activity in inhibiting procoagulant factor VIII, in immunofluorescent studies and by immunoelectrophoretic techniques. A method for titrating precipitating antibody to factor-VIII related protein using counter-immuno-electrophoresis is described. Four of the antisera possessed both precipitating antibody to factor VIII related protein and inhibitory activity against procoagulant factor VIII. These antisera reacted by immunofluorescence or immunoprecipitation methods with a factor VIII related antigen or antigens in normal platelets and in the platelets of a patient with severe von Willebrand's disease although antigen could not be detected in the patient's plasma. The other antiserum had specific precipitating activity against factor VIII related protein but it did not inhibit procoagulant factor VIII. It reacted with normal platelets by both immunoprecipitation and immunofluorescent techniques but it did not react with the severe von Willebrand's disease platelets. The results show that although the antisera appeared to contain a single antibody giving reactions of identity when examined by simple immunodiffusion some of them in fact contained antibodies with different characteristics.