| Coronary heart disease is the one of the major cause of death in the world. Percutaneous transluminal coronary angioplasty has become the preferred method for treating coronary artery stenosis. However, the major drawback of this technique is the relatively high rate of restenosis that occurs within 6 months in 40%~60% of all case, and the problem of restenosis hasn't been solved in clinic up to now. Among the various means at overcoming restenosis, endovascular brachytheray is a promising approach. In this study, we mainly performed the endovascular brachythreapy studies in animal restenosis model. The results of this study can provide theoretic guide for clinical trials and applications.Part â… Generator Elution and Concentration of Rhenium-188 The aim of this part of study is to investigate the producer of generator elution and concentration of 188Re in order that high specific activity of 188Re was available for animal experiment. Elution curve revealed almost total available 188Re could be removed by 20ml saline and the highest specific activity occurred in the ninth millilitre (2.43GBq ). Daily elution provided about 58.4% of total available 188Re and more than 90% of total available 188Re could be obtained 72 hours after removal of 188Re. By using silver cation and anion exchange column, the desired specific activity of 188Re could reach more than 9.25GBq/ml,which could meet the need of clinical intravascular brachytheray use. The flow rate of 1ml/min and the 15ml volume of saline is the optimum condition for concentration.Part â…¡ Preparation of RadiopharmaceuticalRhenium-188-labelled DTPA and Its Biodistribution in RatsThe purpose of this part of article is establishing a useful and stable method for the prepareation of 188Re-DTPA and investigating biodistribution of 188Re-DTPA and 188ReO4- in rats to assess the resulting organ dose values in the event of balloon rupture if these agents are used for the clinical inhibition of restenosis after PTCA .Thirty male SD rats were divided into two groups at random. After injecting 188Re-DTPA or 188ReO4- (18.5MBq/0.1ml) intravenously, rats were sacrificed at 10min, 30min, 60min, 2h, 6h (n=3 per group). Tissue concentrations were calculated and expressed as percent injected dose per gram or per ml (%ID/g or %ID/ml). From distribution data of two agents in rats, the radiation absorbed doses for various tissues in human were estimated. Our data showed the labeling efficiency of 188Re - DTPA was higher than 95% by varying the parameters and in vitro stability of 188Re-DTPA was good under the optimized condition. The optimum concentrations of SnCl2 and DTPA for preparation of 188Re-DTPA were both 10mg/ml and the optimum conditions were pH0.5, a reaction time of 30min at temperature of 100OC. The results of biodistribution studies demonstrated that radioactivity levels of Re-188 perrhenate in the thyroid gland and stomach were higher than that of 188Re-DTPA, furthermore, the excretion of 188Re-DTPA was much faster than that of 188Re perrhenate. The data of estimated doses to various tissue in human revealed the estimated radiation doses to thyroid gland, stomach, kidney is 0.041, 0.043, 0.789 mGy/MBq respectively in 188Re-DTPA group and 0.563, 0.118, 0.111 mGy/MBq respectively in 188ReO4- group. The data of estimated doses showed the same results as that of biodistribution studies. Our study suggested that Re-188-DTPA was superior over 188ReO4- for use in endovascular brachytherapy.Part â…¢ Establishment of Rabbit Iliac ArteryRestenosis Model by Balloon Endothelial DenudationEndovascular brachytherapy study highlight the need for a reliable experimental model for investigating the pathophysiology of restenosis and evaluating irradiational means of preventing its occurrence. An animal model was established by using 2.5-mm balloon catheter to denude endothelium in rabbits iliac artery. Twenty eight days after operation, the tissue cuts were stained with HE (hemalaune hematoxylin and eosin) and Van Gieson for morphologic e... |
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