Plateletpheresis with the COBE spectra single needle access option.

A group of modifications, including a reservoir bag in the return circuit, has been devised to allow single needle plateletpheresis with the COBE Spectra. We compared the number and quality of platelets collected from 10 subjects in paired donations with single and dual needle protocols. There was no evidence of hemolysis with either protocol. Mean (+/- SD) platelet yields were 3.61 +/- 1.47 x 10(11) with two needles and 3.31 +/- 1.31 x 10(11) with the single needle procedure (P = .13). Mean leukocyte levels (standard manual counting chamber) were 1.0 +/- 1.7 x 10(7) and 1.2 +/- 1.0 x 10(7), respectively (p = .78). pH values during storage were acceptable in both groups of concentrates, and there were no significant differences between the single needle and dual needle concentrates in morphology scores or beta-thromboglobulin levels at 0, 1, 3, or 5 days of storage. Thus the single needle modification produced platelets that were comparable in quantity and quality to those from the standard dual needle plateletpheresis protocol.

Differential effects of two doses of aspirin on platelets-vessel wall introduction in vivo.

Platelet cyclooxygenase appears to be more sensitive to aspirin than the arterial endothelial cell cyclooxygenase. To investigate the dose-related effects of aspirin on platelet-vessel wall interaction in acute vascular injury, male New Zealand White rabbits were treated with either (a) aspirin (150 mg/kg body wt; n = 6), (b) aspirin (30 mg/kg; n = 6), or (c) vehicle (n = 10). After treatment, autologous 111In-platelets were injected and deendothelialization of a 10-cm long segment of abdominal aorta was induced by a balloon catheter. Rabbits were killed 3 h after injury and radioactive counts and percentages of injected radioactivity per gram dry weight of tissue or blood were determined. The 30 mg aspirin group had a significantly lower radioactive count (62.13 +/- SD 6.07 x 10(3) cpm) and percentage of injected radioactivity (0.024 +/- 0.003%) per gram dry weight of damaged aortic tissue than the control (1,167.82 +/- 212.31 x 10(3) cpm/g tissue and 0.435 +/- 0.079%, respectively). By contrast, the 150-mg aspirin group had an elevation of radioactive counts (4,343.12 +/- 556.98 cpm) and percentage (1.632 +/- 0.246%) per gram dry weight of damaged tissue. Infusion of exogenous PGI2 was associated with reduction of lesion radioactivity. These findings were supported by ultrastructural findings. Examined under transmission electron microscopy, the injured aortic wall of 30-mg group was covered throughout the segment by a single layer of platelets without detectable platelet aggregates, while that of the 150-mg group was diffusely packed with multiple layers of platelets. The findings demonstrate that aspirin (30 mg/kg) prevents platelet aggregate formation at the injured arterial wall, whereas 150 mg/kg promotes platelet thrombus formation.