Peter Muschick

Reduction of Intimal Hyperplasia withRe-188-labeled Stents in a Rabbit Model at 7and 26 Weeks: An Experimental Study

The aim of this study was to analyze the feasibility of 188Re-labeled stents to reduce neointimal formation in a rabbit atherosclerosis model and to test the long-term effects at 7 and 26 weeks. Fifty-nine male New Zealand White rabbits were fed a 0.5% cholesterol diet for 4 weeks before balloon angioplasty and insertion of Palmaz stents in the infrarenal aorta. The animals were sacrificed 7 and 26 weeks after stent implantation. Control stents were compared with 188Re stents: (dose 1) 11.3u2009±u20091.8 MBq; (dose 2) 37.3u2009±u20094.2 MBq, and (dose 3) 80.1u2009±u20097.8 MBq. Each activity group consisted of a short-term (7 weeks) and a long-term group (26 weeks), resulting in a total of eight study groups. No thrombotic occlusion was observed. The neointimal formation in the control group was 2.11 [95% confidence interval (CI): 0.68–6.52] mm2 at 7 weeks and 2.10 (0.62–7.11) at 26 weeks. In the treatment groups, neointima reduction was detectable at 7 weeks [dose 1: 0.33 (0.09–1.22) mm2; dose 2: 0.17 (0.05–0.57) mm2; dose 3: 0.03 (0.01–0.13) mm2]. After 26 weeks, a catch-up of neointimal formation in the radioactive groups was most obvious in the low-dose group [dose 1: 0.80 (0.28–2.29) mm2; dose 2: 0.18([0.06–0.52) mm2; dose 3: 0.50 (0.17–1.42) mm2]. Compared to the long-term control group, neointimal reduction was still >60%. No induction of neointimal formation was observed at the edges of the stents. Radiation resulted in delayed re-endothelialization. 188Re stents were capable to reduce intimal hyperplasia and did not cause thrombosis. The edge effect, which was the major limitation of 32P stents, was not observed in 188Re stents.

Lipid Dependent Cardio- Haemodynamic Tolerability of Liposomes in Rats

AbstractRationale and Objectives:The use of contrast-carrying liposomes in diagnostic applications (1) or of haemoglobin liposomes in blood replacement therapy (2) requires infusion of large lipid doses. Saturated lipids like HSPC are often used in these formulations to render the liposomes more stable (3). Previous studies have indicated that intravenous injection of such liposome preparations can result in significant haemodynamic changes in rats (14). The purpose of this study was to systematically evaluate cardio- and haemodynamic effects of liposomes prepared from saturated and unsaturated phosphatidylcholine alone or in combination with other lipid components.Methods;Liposomes made from SPC, HSPC, DSPC, DSPC/CH, DSPC/DSPG, DSPC/CH/DSPG were infused in anaesthetized rats (total lipid dose: 300 mg lipid/kg BW) and cardio-heamodynamic parameters were measured.Results:DSPC-liposomes significantly reduced blood pressure (BP) and total peripheral resistance (TPR) by -53.7 % and -45.7 % of prevalue, respec...