potassium-cyanate and Anemia--Hemolytic

During advanced renal failure, and particularly in patients with end-stage renal disease, proteins are carbamylated as a result of a reaction with cyanate. If the carbamylation of proteins adversely alters their biologic activities and structures, then urea must be viewed as an uremic toxin, rather than a surrogate. Therefore, we studied in this paper the role of cyanate as a hemolytic factor of erythrocytes to explain anemia observed in patients with high blood urea levels due to inadequate dialysis. Cyanate was added to make the final concentration 150, 300 and 600 nmol to each test tube containing the final concentration of 140 x 10(6) with human erythrocytes per mL of phosphate buffered saline solution. And they were incubated at 37 degrees C for 24, 48 and 72 hours. The extent of hemolysis and carbamylation was monitored. The levels of hemolysis and carbamylated erythrocytes increased as the time of exposure to cyanate increased from 24 hours to 72 hours. Furthermore, those increased as cyanate concentration in the incubation media rose from 150 nmol to 600 nmol. Cyanate can induce hemolysis by carbamylation of erythrocytes. Urea, through cyanate, may contribute to hemolysis. If one extrapolates these results to patients with end-stage renal disease, it may help explain one of the reasons for the anemia in patients with high levels of BUN due to inadequate dialysis.

Topics: Anemia, Hemolytic; Blood Urea Nitrogen; Cyanates; Erythrocytes; Hemolysis; Humans; Kidney Failure, Chronic

Red cell survival was studied with use of Chromium-51 isotope and standard haematologic tests of haemolysis. The study comprised 30 patients with normally functioning single artificial heart valves of various types. They were investigated on 2 or 3 occasions. Red cells labelled with Cr-51 were treated for 30 min with potassium cyanate (0.5 mg/100 ml) in 5% invertose or with only 5% invertose. The mean red cell survival without cyanate treatment was 25 (+/- 4.2) days. Following cyanate treatment this figure improved to 31 (+/-4.8) days. Low-grade chronic intravascular haemolysis was associated with all the valve types. Abnormal results were found in 67% and 62% of the tests in patients with ball-type valve (deBakey and Starr-Edwards, respectively). The figures for tilting disc values (Lillehei-Kaster and Björk-Shiley) were 51 and 45.5%, while Carpentier-Edwards bioprosthetic valves gave 15.5% abnormal test results. The findings thus suggested that ball valves are more haemolytic than tilting disc valves, which in turn are more haemolytic than tissue valves.

Topics: Anemia, Hemolytic; Aortic Valve; Chromium Radioisotopes; Cyanates; Erythrocyte Aging; Heart Valve Prosthesis; Humans; Mitral Valve; Prosthesis Design