Patients with severe uremia may have a bleeding tendency associated with a prolonged bleeding time and an adequate platelet count. We have tested the effects on platelet aggregation of three compounds that are found in increased concentration in the blood of patients with renal failure. The addition of urea was followed by an immediate, but transient, increase in optical density of platelet-rich plasma. This precluded the use of turbidimetric techniques for the measurement of platelet aggregation after addition of urea, until the optical density became stable. Adenosine diphosphate-, collagen-, and norepinephrine-induced platelet aggregation were shown to be inhibited 1 hr after urea was added to platelet-rich plasma to produce urea nitrogen increments of 100-300 mg/ 100 ml. Increasing concentrations of creatinine by 10 or 20 mg/100 ml did not inhibit platelet aggregation. Guanidinosuccinic acid, in a concentration in the range found in uremic plasma, also had no effect on platelet aggregation. Through inhibition of platelet aggregation, elevated blood concentrations of urea may be one of the causes of the bleeding tendency of uremic platients.
SummaryThe composition of plasma non-esterified fatty acids was investigated during glucose tolerance tests to determine changes in individual fatty acid concentrations after glucose administration and to determine whether differences existed between the individual fatty acid concentrations of maturity-onset diabetic and non-diabetic men. The mean fasting total nonesterified fatty acid concentration of the 9 diabetics was greater than that of the 12 non-diabetics studied. After glucose ingestion, the mean total non-esterified fatty acid concentrations of both groups decreased. Gas chromatographic analysis of the plasma nonesterified fatty acids of 6 diabetic and 6 non-diabetic men revealed that the concentrations of palmitic, stearic and oleic acids were significantly higher in the diabetic men in the fasting state. With the sole exception of stearic acid in the non-diabetic patients, the mean concentration of each of the 6 plasma nonesterified fatty acids determined decreased in both groups after glucose ingestion. At 1, 2 and 3 hr after glucose ingestion, there were no longer any significant differences between the mean concentrations of individual plasma non-esterified fatty acids of the non-diabetic and diabetic men.
IntroductionIt is well established that ingestion of glucose or of a high carbohydrate meal by normal humans is followed by a decrease in plasma total non-esterified fatty acid (NEFA) concentration. However, the changes of concentrations of individual NEFA are much less studied, and information on the effect of glucose ingestion on the plasma individual NEFA of diabetic subjects, who are known to have high levels of plasma total NEFA (Schrade et al., 1963),
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