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SummaryTwelve different mutations in the WASP gene were found in twelve unrelated families with Wiskott-Aldrich syndrome (WAS) or X-linked thrombocytopenia (XLT). Four frameshift, one splice, one nonsense mutation, and one 18-base-pair deletion were detected in seven patients with WAS. Only missense mutations were found in five patients diagnosed as having XLT. One of the nucleotide substitutions in exon 2 (codon 86) results in an Arg to Cys replacement. Two other nucleotide substitutions in this codon, R86L and R86H, have been reported previously, both giving rise to typical WAS symptoms, indicating a mutational hot spot in this codon. The finding of mutations in the WASP gene in both WAS and XLT gives further evidence of these syndromes being allelic. The relatively small size of the WASP gene facilitates the detection of mutations and a reliable diagnosis of both carriers and affected fetuses in families with WAS or XLT.

SummaryThe Stormorken syndrome is a multifacetted syndrome including a bleeding tendency. No deviations were found in the coagulation- or fibrinolytic systems. Platelet number was low normal, and size abnormal, whereas EM findings were unremarkable. Survival time was half normal. Clot retraction was initially rapid, but clearly decreased, whereas prothrombin consumption was also initially rapid, but complete. Membrane GP’s were normal, so was AA metabolism, PI-cycle, granule storage and secretion, and c-AMP function, whereas 5-HT uptake and storage was decreased. Optical platelet aggregation was low normal with all physiological agonists. The only clearly abnormal finding was that coagulant activity was present on non stimulated platelets at the same level as kaolin-stimulated normal platelets. This indicated a platelet abnormality which should lead to a thrombogenic, not to a haemorrhagic trait. This paradox may have its origin in rheology, because when challenged with in vivo shear rates in an ex vivo perfusion chamber, platelet cohesion was abnormally low. Further studies to better delineate the membrane abnormality are underway.

SummaryDetailed studies on the rare disorder X-linked thrombocytopenia showed that it resembles the Wiskott-Aldrich syndrome (WAS) in inheritance, clinical bleeding tendency, platelet morphology, marked thrombocytopenia and microplatelets. The calculated platelet mass was 5% of normal. Functional and biochemical studies indicated qualitatively normal aggregation and release mechanisms, whereas a moderate storage pool defect was present. The classical platelet membrane glycoproteins and lymphocyte sialophorin (CD 43) were normal.The reason for the bleeding tendency was concluded to be deficient hemostatic plug formation resulting from the low platelet mass and a moderate storage pool defect.The only clear distinction from WAS was the normal immunofunctional tests, the moderate tendency to infections and the absence of eczema. We therefore consider the trait as an attenuated form of WAS. That women are affected may indicate a particular variant.

SummaryA novel mutation in the factor VII gene resulting in procoagulant activity of 7.5% and antigen levels of 23% is presented. Single-stranded conformational polymorphism and DNA sequencing analysis revealed heterozygous shifts, and mutations were detected in exons 5, 7 and 8. The mutant L204P in exon 7 was novel, while the common polymorphisms, H115H and R353Q, were located in exons 5 and 8, respectively.The molecular effect of the L204P mutation was characterized using recombinant mammalian expression in Chinese hamster ovary cells. Low levels (4 ng/ml) of secreted mutant protein were found in transiently transfected cells compared to wild-type factor VII (83 ng/ml). Metabolic labeling demonstrated that the rate of mutant protein synthesis was similar to that of wild-type FVII, and the mutant protein accumulated intracellularly with no signs of increased degradation during a four-hour chase. No interaction between secreted P204 protein and immobilized soluble tissue factor was detected using surface plasmon resonance. The activation rate of recombinant mutant FVII protein was strongly reduced compared to wild-type FVII. A 9-fold reduction in the rate of FX activation was detected whereas Km was nearly the same for wild-type and the mutant. This slow rate was caused by a correspondingly lowered rate of P204 activation. A synthetic peptide sequence comprising amino acids 177−206 blocked binding of FVIIa to the TF-chip, and the subsequent factor X activation with an IC50 value of 0.5 μM in a chromogenic factor Xa assay. Additionally, evaluation of the peptide by surface plasmon resonance analysis resulted in inhibition of complex formation with an apparent Ki of 7 μM.

SummaryA missense mutation at codon 100 in the second epidermal growth factor-like domain, resulting in Gln100→Arg, was detected in 19 out of 21 available severely factor VII (FVII) deficient patients in Norway. Seventeen patients were homozygous, and the two remaining were compound heterozygotes. In the homozygous patients, FVII antigen was measured to 10-28%, and activity to 0.6-6.5% of that in normal pooled plasma. Recombinant FVII containing the mutation was expressed transiently in CHO cells to a mean antigen level of 57% of the wild type FVII protein, and with a specific activity of 6% of wild type. The mutant protein had a 14-fold reduction in affinity for tissue factor (TF), whereas binding of FX seemed unaffected. In line with the experimental data, molecular modelling of the mutation based on the coordinates of the tissue factor/FVIIa complex showed that substituting arginine for glutamine disrupts the interface between the catalytic and second epidermal growth factor-like domains.

The Stormorken syndrome is a multifacetted syndrome including a bleeding tendency. No deviations were found in the coagulation- or fibrinolytic systems. Platelet number was low normal, and size abnormal, whereas EM findings were unremarkable. Survival time was half normal. Clot retraction was initially rapid, but clearly decreased, whereas prothrombin consumption was also initially rapid, but complete. Membrane GP's were normal, so was AA metabolism, PI-cycle, granule storage and secretion, and c-AMP function, whereas 5-HT uptake and storage was decreased. Optical platelet aggregation was low normal with all physiological agonists. The only clearly abnormal finding was that coagulant activity was present on non stimulated platelets at the same level as kaolin-stimulated normal platelets. This indicated a platelet abnormality which should lead to a thrombogenic, not to a haemorrhagic trait. This paradox may have its origin in rheology, because when challenged with in vivo shear rates in an ex vivo perfusion chamber, platelet cohesion was abnormally low. Further studies to better delineate the membrane abnormality are underway.

SummaryIn 386 men aged 40–49 years the number of platelets was related to differences in smoking habits. “Platelet adhesiveness” (retention) was estimated by a glass bead filter method in 376 of these men. The estimation of “adhesiveness” was performed in native blood without anticoagulants at least 12 hr after the last cigarette smoked. A small but statistically highly significant increase in platelet count, in number of “adhesive platelets” and percentage of “adhesive platelets” was found in smokers as compared with non-smokers, the highest values being found in the heaviest smokers and vice versa. Such smoking-related changes in platelet count and reactiveness might unfavourably influence the tendency towards coronary thrombosis, and might in part explain the deleterious effects of smoking on coronary heart disease morbidity and mortality.

SummaryThe view based on epidemiological and laboratory data that blood group A subjects (=A) have clinically significant higher thrombotic potential than blood group 0 subjects (= O), is supported by the present finding of a significantly higher platelet retention in A than 0.The completely normal ABO distribution found among 71 cases of proven latent CHD, and the disproportionate excess of 0 vs. A in a consecutive series of 191 coronary artery bypass candidates apparently conflict with epidemiological data indicating a higher risk of achieving CHD in A than 0. The conflict may be solved by suggestinga) that the »thrombotic proneness« in A compared with 0 causes a poorer prognosis in CHD among the former, leaving a disproportionate excess of 0 among longterm CHD survivors, and b) that AB0-related factors have had an insignificant, independent impact on the evolution of preclinical coronary artery disease in our 71 men with latent CHD.

SummaryA study of a family with a propositus suffering from classical thrombasthenia type I has shown that the new immunochemical methods detect heterozygotes with high reliability. There was no overlapping between heterozygotes and normals, and the concentration of the glycoprotein IIb-IIIa-complex is remarkably constant around 50–60% in the heterozygotes. Furthermore, heterozygotes as a group show an increased bleeding tendency.

SummaryIn a prospective study on latent coronary heart disease (CHD) in 2,014 presumably healthy men aged 40–59 years, 115 had strong clinical evidence of CHD never diagnosed nor suspected prior to the survey. Coronary angiography was performed in 105 of these. In 80 of them – whereof 57 were angiopositive and 23 angionegative – AT III and factor VIII Ag were assayed as well as in 35 normals from the same material. The results showed that:1. AT III was significantly lower in the angiopositive than in the normal controls.2. Subdivision of the angiopositive into those with and those without angina pectoris revealed significantly lower level of AT III in the former.3. Within blood group A only did the angiopositive subjects have significantly lower AT III than the remaining subjects in the group, and this was entirely due to the low values in those with angina pectoris.4. Blood group 0 individuals had significantly lower factor VIII Ag level than all other blood groups.The significance of these findings for the possible relation to development of atheromatosis is briefly discussed.

Summary and Conclusions1. Moderate doses of heparin often prolonged the bleeding time in men, rats and mice. The bleeding was wavelike, and a sensitive method was necessary to demonstrate the prolongation.2. Large doses gave a prolonged bleeding time, and the bleeding was often profuse and continuous.3. Heparin did not produce thrombocytopenia. Moderate doses probably prevent viscous metamorphosis and fibrin formation, resulting in large but inefficient platelet plugs. Large doses may also interfere with the aggregation of platelets, preventing the formation of platelet plugs.

SummaryA family with dysfibrinogenemia is described. The abnormal fibrinogen occurred in three successive generations indicating a dominant hereditary pattern. Thrombin and reptilase times were about twice the normal value. This was shown to be caused by a polymerization defect, fibrinopeptide release being normal. Platelet aggregation was undisturbed, indicating normal platelet-fibrinogen binding. The bleeding time was normal and there was no bleeding tendency. However, an obscure recurrent pulmonary ailment may, or may not, be related to the dysfibrinogenemia. The abnormal fibrinogen was tentatively termed Oslo IV.

SummaryA method for visualization of the multimeric forms of von Willebrand Factor (vWF) in plasma and platelets is described. The method is based upon: 1) Separation of the vWF multimers by SDS-agarose electrophoresis, 2) Subsequent blotting of the vWF multimers onto nitrocellulose, 3) Immunolocalization and visualization of the vWF pattern by the sequential incubation of the blot with a) primary vWF antiserum, b) peroxidase- or beta-galactosidase-conjugated secondary antibodies and a relevant chromogenic substrate.

Plasma factor 7 was found increased to 5-20 times normal in the plasma stored overnight between -5 and 0 degrees C in women using oral contraceptives. This might cause the observed shortening of thrombotest time in stored plasma. The activation of factor 7 is dependent on facto r 12. The system was inhibited by trasylol and soybean trypsin inhibitor (STI). Epsilon aminocaproic acid (EACA) or aminomethyl cyclohexane-carboxylic acid (AMCA) had no effect.

A method for visualization of the multimeric forms of von Willebrand Factor (vWF) in plasma and platelets is described. The method is based upon: 1) Separation of the vWF multimers by SDS-agarose electrophoresis, 2) Subsequent blotting of the vWF multimers onto nitrocellulose, 3) Immunolocalization and visualization of the vWF pattern by the sequential incubation of the blot with primary vWF antiserum, peroxidase- or beta-galactosidase-conjugated secondary antibodies and a relevant chromogenic substrate.

The view based on epidemiological and laboratory data that blood group A subjects (=A) have clinically significant higher thrombotic potential than blood group 0 subjects (=O), is supported by the present finding of a significantly higher platelet retention in A than 0. The completely normal AB0 distribution found among 71 cases of proven latent CHD, and the disproportionate excess of 0 vs. A in a consecutive series of 191 coronary artery bypass candidates apparently conflict with epidemiological data indicating a higher risk of achieving CHD in A than 0. The conflict may be solved by suggesting a) that the "thrombotic proneness" in A compared with 0 causes a poorer prognosis in CHD among the former, leaving a disproportionate excess of 0 among longterm CHD survivors, and b) that AB0-related factors have had an insignificant, independent impact on the evolution of preclinical coronary artery disease in our 71 men with latent CHD.