673
subsequent intracellular reduction and liberation of a thiol into the extracellular spaceExtracellular reoxidation of the thiol may then lead to univalent reduction of oxygen to give superoxide. Consistent with this view, reduced sulphur-containing aminoacids have been reported to modify LDL in cell-free systems, producing all of the changes observed in LDL modified by cells.4 In addition to its function as a sulphydryl donor, NAC is a free oxygen radical scavenger, and inhibits human monocyte superoxide and chemotaxisTherefore, NAC may influence atherogenesis by several mechanisms.
generation
Department of Medicine B, Division of Cardiology, University of Copenhagen, 2100 Copenhagen, Denmark
PETER RIIS HANSEN
1 Mitchinson MJ, Ball RY. Macrophages and atherogenesis. Lancet 1987; ii: 146-49. 2. Steinberg D, Parthasarathy S, Carew TE, Khoo JC, Witztum JL. Beyond cholesterol-modifications of low density lipoprotein that increase its atherogenicity. N Engl J Med 1989; 320: 915-24. 3. Hiramatsu K, Rosen H, Heinecke JW, Wolfbauer G, Chait A. Superoxide initiates oxidation of low density lipoprotein by human monocytes. Arteriosclerosis 1987; 7:
55-60. 4. Heinecke JW, Rosen H, Suzuki LA, Chait A. The role of sulphur-containing amino acids in superoxide production and modification of low density lipoprotein by arterial smooth muscle cells. J Biol Chem 1987; 262: 10098-103. 5. Aruma OI, Halliwell B, Hoey BM, Butler J. The antioxidant action of Nacetylcysteine: its reaction with hydrogen peroxide, hydroxyl radical, superoxide and hypochlorous acid. Free Rad Med Biol 1989; 6: 593-97.
Low-dose aprotinin for reduction of blood loss after cardiopulmonary bypass SIR,-Several studies have shown that high-dose aprotinin significantly reduces both blood loss and blood transfusion requirements in patients who have undergone cardiac surgery with cardiopulmonary bypass.1,2 We have investigated, in a double-blind randomised trial, the effects of a reduced dosage of aprotinin on blood loss and blood transfusion requirements in patients who received elective coronary artery bypass grafting. All patients were operated on by standard techniques that included cardiopulmonary bypass (CPB) with moderate hypothermia. Group A (n = 13) was a control group. Patients in group B (n = 11) were given 2 x 106 KIU aprotinin as an intravenous injection during induction of anaesthesia over 30 min. Patients in group C (n = 12) received the same dose, but in the priming volume of the extracorporeal circulation only. Group D patients (n=20) received high-dose aprotinin (2 x 1()6 KIU aprotinin as an intravenous bolus with 2 x 106 KIU in the priming volume of the extracorporeal circulation and 500 000 KIU intravenously per hour during operation). Results are shown in the figure. Significant differences were found between groups A and C (p
subsequent intracellular reduction and liberation of a thiol into the extracellular spaceExtracellular reoxidation of the thiol may then lead to univalent reduction of oxygen to give superoxide. Consistent with this view, reduced sulphur-containing aminoacids have been reported to modify LDL in cell-free systems, producing all of the changes observed in LDL modified by cells.4 In addition to its function as a sulphydryl donor, NAC is a free oxygen radical scavenger, and inhibits human monocyte superoxide and chemotaxisTherefore, NAC may influence atherogenesis by several mechanisms.
generation
Department of Medicine B, Division of Cardiology, University of Copenhagen, 2100 Copenhagen, Denmark
PETER RIIS HANSEN
1 Mitchinson MJ, Ball RY. Macrophages and atherogenesis. Lancet 1987; ii: 146-49. 2. Steinberg D, Parthasarathy S, Carew TE, Khoo JC, Witztum JL. Beyond cholesterol-modifications of low density lipoprotein that increase its atherogenicity. N Engl J Med 1989; 320: 915-24. 3. Hiramatsu K, Rosen H, Heinecke JW, Wolfbauer G, Chait A. Superoxide initiates oxidation of low density lipoprotein by human monocytes. Arteriosclerosis 1987; 7:
55-60. 4. Heinecke JW, Rosen H, Suzuki LA, Chait A. The role of sulphur-containing amino acids in superoxide production and modification of low density lipoprotein by arterial smooth muscle cells. J Biol Chem 1987; 262: 10098-103. 5. Aruma OI, Halliwell B, Hoey BM, Butler J. The antioxidant action of Nacetylcysteine: its reaction with hydrogen peroxide, hydroxyl radical, superoxide and hypochlorous acid. Free Rad Med Biol 1989; 6: 593-97.
Low-dose aprotinin for reduction of blood loss after cardiopulmonary bypass SIR,-Several studies have shown that high-dose aprotinin significantly reduces both blood loss and blood transfusion requirements in patients who have undergone cardiac surgery with cardiopulmonary bypass.1,2 We have investigated, in a double-blind randomised trial, the effects of a reduced dosage of aprotinin on blood loss and blood transfusion requirements in patients who received elective coronary artery bypass grafting. All patients were operated on by standard techniques that included cardiopulmonary bypass (CPB) with moderate hypothermia. Group A (n = 13) was a control group. Patients in group B (n = 11) were given 2 x 106 KIU aprotinin as an intravenous injection during induction of anaesthesia over 30 min. Patients in group C (n = 12) received the same dose, but in the priming volume of the extracorporeal circulation only. Group D patients (n=20) received high-dose aprotinin (2 x 1()6 KIU aprotinin as an intravenous bolus with 2 x 106 KIU in the priming volume of the extracorporeal circulation and 500 000 KIU intravenously per hour during operation). Results are shown in the figure. Significant differences were found between groups A and C (p
