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When isolated rat livers were perfused with platelet-free erythrocytes suspended in Tyrode’s solution containing 6% bovine serum albumin, the generation of factors V, XI, and XII was clearly demonstrable. On average, after 5 h of perfusion of a single liver, the concentrations in the perfusate (as a percentage of normal rat plasma) were about 6% for factor V, 8% for factor XI, and 5% for factor XII, compared with 20% for factor VII, which was used as the reference standard. When two livers were perfused, approximately twice these concentrations were achieved. When the properties of these factors in perfusate and plasma were compared, they agreed well except for differences in the celite adsorbability of factors XI and XII.

Since patients with myeloproliferative disorders may have bleeding tendencies, the surgeon, in particular, is anxious for an hemostatic evaluation if splenectomy is contemplated. It is known that platelet aggregation, particularly with epinephrine, tends to be reduced in these patients. The nucleotide content of their platelets may be deficient. Furthermore, megakaryocytic fine structure is often abnormal. We have studied, In detail, 9 patients with hemostatic disorders. Diagnoses included polycythemia vera, agnogenic myeloid metaplasia, evolving myeloproliferative disease and erythroleukemia. Ages ranged from 36 to 75 years. Bleeding tendencies, including bruising, operative or postoperative bleeding, melena, hematuria, and hemarthrosis, characterized 8 of the 9 patients; the one exception had normal platelet ADP and elevated ATP. All had abnormal platelet aggregation, but the extent of the abnormality could not be related to the ADP and ATP contents of the platelet.ADP (normal 26.7 ± 6.5 nmol/109 platelets) was reduced in 7. ATP (normal 38.6 ± 7.6 nmol/109 platelets) was reduced in 1, elevated in 2 and normal in the other 6. In no patient were both values normal. Nucleotide release induced by collagen activation was measured in 6 of the patients. In all 6 it was deficient whether platelet ADP were normal (1 case) or depressed (5) and whether platelet ADP were elevated (1) or decreased (3).