The Standardized Normal Ivy Bleeding Time and Its Prolongation by Aspirin

A standardized, reproducible Ivy bleeding time technic has been describedwhich permits one to obtain accurate bleeding time data in man. Thetechnic was used to standardize an aspirin tolerance test in which 60 normal males had a control bleeding time; were given, on a double blind basis,either placebo or 1 Gm. of aspirin, and had a second bleeding time 2 hourslater. The control values were: mean, 5 min.; mean ± 2 st. dev., 2 min.,30 sec. to 10 min. The values after placebo were: mean, 5 min., 30 sec.;mean ± 2 st. dev., 2 min., 30 sec. to 11 min. The values after aspirin were:mean, 9 min., 30 sec.; mean ± 2 st. dev., 4 min. to 21 min. The differencebetween the mean bleeding time after placebo and after aspirin was highlysignificant (p < 0.001). The distribution of the bleeding times after aspirinsuggested that normal subjects do not respond to aspirin as a single population. The degree of prolongation of the bleeding time and the large size ofthe drops of blood observed in some subjects suggested to us that smallamounts of aspirin may exert a significant effect upon hemostasis in normalindividuals.

Submitted on January 10, 1969 Accepted on April 23, 1969     

Increased Hemolysis after Intramuscular Iron Administration in Patients with Paroxysmal Nocturnal Hemoglobinuria: Report of Six Occurrences in Four Patients, and Speculations on a Possible Mechanism

Four patients with PNH were described who developed accelerated activityof their disease after the intramuscular administration of iron-dextran fortreatment of iron deficiency. This was considered to reflect a unique effect ofiron on PNH erythrocytes. It was postulated that this effect resulted from celldamage caused by iron catalyzed peroxidation of erythrocyte lipids, a reaction to which PNH erythrocytes could be unusually susceptible by virtue ofan increased content of unsaturated fatty acids or pro-oxidants or decreasedcontent of antioxidants.

Submitted on August 13, 1964 Accepted on November 11, 1964     

DFP Labeling of Platelets During Recovery from Thrombocytopenia

Rat platelets were labeled with tritiated diisopropylfluorophosphate(³H-DFP) during recovery from acute thrombocytopenia. The results indicated that there was significant labeling of megakaryocytes by ³H-DFPwhich, in the presence of an increased rate of platelet production, resulted inmaintenance of relatively constant values for platelet-bound radioactivity during the period of maximum platelet production and reactive thrombocytosis.Significant random loss of platelets was apparent, and, when a cohort ofyoung platelets was transfused to normal recipients, they were destroyed at anormal rate.