Abstracts 903 crossed immunoelectrophoresis in some patients with von Willebrand's disease (vWd) and these investigations have now been extended to a study of over 14 patients. In those with reduced levels of FVIIIRP, concentrates were prepared by precipitation with 3% ethanol at -3° C. The results showed that in three cf the patients with "typical vWd" in whom levels of procoagulant factor VIII and FVIIIRP were parallel and both always reduced the latter had abnormal electrophoretic mobility indistinguishable from that of the "atypical" cases. In all patients in whom abnormal FVIIIRP was demonstrated the time was grossly prolonged and ristocetin aggregation grossly impaired. In patients in whom the mobility of FVIIIRP was indistinguishable from normal the bleeding times and ristocetin platelet aggregation were sometimes less severely impaired despite gross reduction of the circulating level of FVIIIRP. It is suggested that in vvVd synthesis of abnonnal variants cfFVIIIRP is relatively common but that in some patients there is reduced syntehsis of normal FVIIIRP.

L. Holmberg ( Laboratory, Allmanna Sjukhuset, Malmo, Sweden): Variants of von Willebrand's Disease in Sweden. (395) In a recent Swedish investigation we could assign 39 families with all together 100 affected members to the classical type of von Willebrand's disease with low f VIII antigen ( < 50%), low f VIII activity, prolonged BT, decreased platelet retention and ristocetin aggregation and typical response to infusion. A second type was found in 4 families (8 affected members). F VIII antigen was in the normal range and fVIII activity was slightly low or low normal. The other diagnostic criteria were present. A third variant was charac- terized by low f VIII antigen, prolonged BT and reduced platelet retention but normal f VIII activity and only slightly reduced ristocetin aggregation. The disease was sympto- matic only in homozygous form. A fottrth variant characterized by low f VIII activity, prolonged BT, normal f VIII antigen and normal ristocetin aggregation, was found in 7 families. As some of the pedigrees strongly suggests X-chromosomal inheritance, a variant should rather be considered. In addition to the Swedish material some descendants of von Willebrand's original families on Aland (Finland) have been examined.

M . .Aberg, U. Hedne1·, L. Holmberg and S. E. Bergentz (Allmanna Sjukhuset 21401 Malmo, Sweden): Dextran Induced Changes of the Factor VIII Molecule. (396) 500 ml of dextran -70 (6% in saline) was given during 30 min to 10 healthy young men. This had no effect on factor VIII-activity (one-stage clotting assay), but r esulted in an immediate decrease of factor VIII-related (imm. chem. assay). The decrease was maximal 2-4 hours after infusion (initial mean value lll.1%; mean after 4 hours 85.9%; p < 0.001). There was a parallel decrease in platelet adhesiveness (method of Salzman) in two analysed subjects (16% and 14% ; initial values 50% and 60% resp.), and a significantly decreased ristocetin aggregation of plasma from all analysed subjects (5) was seen. Factor VIII-activity after gel filtration of plasma showed a different elution pattern after dextran infusion. These findings are in accordance with those seen in a variant fo v. Willebrand's disease in which an abnormal factor VIII-related protein was demonstra of v. Willebrand's disease in which an abnormal factor VIII-related protein was de- monstrated (Holmberg et al, 1975). Dextran is therefore suggested to interfere with the This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. factor VIII molecule resulting in a defect primary haemostasis.

W. V. Humphreys, A. W allcer and D. Charlesworth, University Hospital of South Manchester, Nell Lane, Manchester 20, England: Abnormal Blood Yield Stress as an Aetiolog·ical Factor in Postoperative Deep Venous . (397) An elevated blood viscosity could lead to increased venous stasis and a higher incidence of post-operative . Immediately preoperatively we have measured, using a Contraves low shear 2 viscometer, blood yield stress and viscosity at high and low shear rate in 28 general surgical patients. These patients were then screened by the 904 Abstracts standard P 25 technique to detect the development of deep vein thrombosiR post-operatively. 13 patients developed a deep vein thrombosis. These patients had a significantly higher blood yield stress, corrected to a standard haemocrit of 45%, than the others (P < 0.01 students t). All other viscosity parameters were normal in these patients. Patients with malignant disease had a very high incidence of thrombosis (90% : 30%) and significantly higher yield stress values (mean 0.26 dynes/cm 2 : mean 0.194 dynes/em", P < 0.0001) students t) compared to patients with benign disease. We conclude that a high blood yield stress could be an important aetiological factor in thrombosis and the high values obtained in patients with malignant disease could partly explain the high incidence in these patients.

W. T . Millar and J. F. B. Smith (West of Scotland Health Boards, Department of Clinical Physics and Bio-Engineering, ll West Graham Street, Glasgow and Falkirk and District Royal Infirmary, Major's Loan, Falkirk): The Detection of Deep Using Labelled . (398) The use of 125I-labelled fibrinogen in the detection of venous thrombosis in the lower limbs is well established. However, the technique is limited in applicability since only actively forming thrombi may be detected efficiently. Urokinase, a fibrinolytic enzyme, has been labelled with 99mTc and found to be suitable for the detection and localisation of venous thrombi. Iodinated urokinase has also been investigated. The use of "mTc-labelled urokinase allows the lower limbs and the pelviR to be scanned using either a rectilinear scanner or a gamma camera, whereas with iodinated urokinase the hand monitor method used in the fibrinogen technique is used. The fibrinolytic activity of the labelled urokinase was evaluated using the plate technique in order to verify that the urokinase was not denatured in the labelling process. In the series of patients studied, venography was undertaken when possible for comparison with the urokinase scan. The time between the onset of clinical symptoms and urokinase scanning ranged frorn two days to several months suggesting that both active and formed thrombi may be detected. In order to exclude non-specific uptake by the thrombi, several patients with unilateral calf thrombosis were scanned with ••mTc-labelled human serum albumen. The labelled urokinase was injected intravenously and scanning initiated after 15 minutes in order to allow the circulating blood level to stabilise.

J. Plante, B. Boneu and J. Gaillard (Lab. Hemostase, Centre de Transfusion Sanguine, Hopital Purpan, B. P. 3210-31052 Toulouse Cedex France): lnaccurancies of Clotting Tests in Early Diagnosis of Post-Operative Deep Vein Thrombosis (D. V. T.). (399) Two groups of pneum.onectomized patients with diagnosis of pulmonary carcimona were successively studied to assess the diagnostic and predictive values of some clotting test in post-operative D. V. T. The incidence of D. V. T. was determined by the 125I fibrinogen method. Simultaneously blood clotting tests including thromboelastography (T. E. G.), P. T. T. platelet count, fibrinogen level, F. D.P. assay, ethanol test were on the 2d, 4th, and 7th post-operative performed both before and after the surgical procedure This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. days. The first group (32 patients) received subcutaneous Heparin begiru1ing on the third post-operative day. The dose (5000 to 10000 u T. I. D.) was adapted according to the results of the T. E . G. in an efford to obtain an isocoagulable state. The second group (45 patients) received 5000 u of heparin subcutaneously (B. I. D.) with the first injection two hours before the surgical procedure; the dose was adapted on the third day according to the T. E. G. The results of this study show: ( 1) The frequency of blood clotting disturbances is similar in both groups in spite of pre-operative heparinotherapy. (2) The first group presented :five D. V. T . and two fatal pulmonary embolisms whereas the seccnd group