Minipool PCR testing after virus enrichment was sensitive enough to identify HBsAg-negative donors who had seroconverterd and HBsAg-negative, anti-HBc-positive chronic HBV carriers. HBV NAT in conjunction with anti-HBc screening would reduce the residual risk of transfusion-transmitted HBV infection.
The yield of NAT in central European Red Cross blood donors was less than expected from theoretical calculations for American and German multiple-time donors. Look-back procedures for HCV and HIV indicated that no donation given before seroconversion of the donor was missed by minipool PCR. Sensitivity of minipool PCR testing after virus enrichment seems to be sufficiently high to close the diagnostic window almost completely.
A method to induce microthrombi in small mesenteric arteries (ø 15–25 μm) has been developed to study platelet reactions and to investigate antithrombotic drugs. A high power water immersion interference contrast system, based on a Leitz Orthoplan microscope, was used. In Nembutal-anesthetized male Wistar rats and in fawn hooded bleeder rats, vascular lesions were produced with a Hadron-512-Ruby-bio-laser or with a Coherent CR-2 supergraphite ion laser (Argon laser). The ruby laser produced intravascular precipitates consisting of proteins and erythrocytes which usually stuck to the vessel wall and on which platelets immediately adhered, transformed with pseudopode formation and formed loose aggregates. The Argon laser induced vascular damage, usually without intravascular heat precipitates which also led to platelet adhesion, transformation and aggregation. Fibrin threads rarely formed in the early platelet thrombi. Thrombus formation was significantly reduced in this model by dipyridamole (10 mg/kg orally), by Ditazole (50 mg/kg orally), heparin (100 IU/kg i.v.), Molsidomine (50 mg/kg orally), Nafazatrom (Bay G 6575, 10 mg/kg i.v. and orally), Ticlopidine (100 and 200 mg/kg orally) and Tioxaprofen (EMD 26644, 10 mg/kg orally). Thrombus formation was also significantly reduced in fawn hooded bleeder rats.
Laser-induced thrombi have been frequently produced in rat mesenteric vessels to investigate the effect of antithrombotic drugs. We have tested low molecular heparins in comparison to unfractionated heparin. The investigations were carried out on male Wistar rats weighing 200–300 g; the animals were anesthetized with pentobarbital sodium (Nembu-tal®) 60 mg/kg i.p. Vascular lesions were induced with a Coherent CR-2 supergraphite ion laser (argon laser) mounted on a Leitz Orthoplan microscope. An intestinal loop was spread on a self-constructed object stage, mounted on the microscope table. The laser beam was directed through the optical path of the microscope on small mesenteric vessels in the fat-free portion of the mesentery. For the evaluation of thrombus formation the number of laser injuries needed to induce a defined thrombus was used. All low-molecular-weight heparins (preparation B, Braun; BR-Z-0601, Braun; CY 216, Choay; Fragmin, Kabi; low molecular heparin, Sandoz and Org 10172, Organon) or unfractionated heparin (Liquemin®; Hoffmann-La Roche) showed a significant and dose-dependent antithrombotic effect after subcutaneous injection, if venules had been damaged. The effect lasted for 48 h, partly for over 48 h. If thrombus formation was studied after intravenous injection into arterioles as well as into venules 8 h after injection, no antithrombotic effect could be demonstrated under the influence of CY 216 or unfractionated heparin.
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