| Project 1 Synthesis and Abnormal Toxicity Text of 18F-MyoZoneObjective:18F-MyoZone was a new type of 18F labbled myocardial perfusion imaging agent.This study reports the synthesis of 18F-MyoZone based on the pervious study.Quality contral and abnormal toxicity text were then conduced which were aimed to evaluate the clinical safety of 18F-MyoZone.Methods:The Sterile 18F-MyoZone was synthesis mainly by nucleophilic substitution,which included 18F replacings the precursor of MyoZone-OTs,HPLC separation,and sterile filtration membrane purification.The properties,radiochemical purity and impurity content of 18f-myozone solution were determined by visual detection,analytical HPLC and chromatography methed.The biosafety of synthesised 18F-MyoZone solution was evaluated by abnormal toxicity test in mice.Results:The total synthesis yields were stable at 39.2%combined with a radiosynthesis time of 70min by the method of 2.0 mg K2CO3,3.0mg K2.2.2,37MBq 18F-F-and 2.0 mg MyoZone-OTs after 100? sealing reaction for 20 min.The contents of ethanol,acetonitrile and amino polyether in 18f-myozone solution were not exceeded the requirements by quality detection,no abnormal impurities were found,no obvious bacterial growth or endotoxin was observed,and it reached the clinical application requirements.Abnormal toxicity text in mice proved that 18f-myozone was highly safe in vivo appication.Conclusion:In this paper,18F-MyoZone solution was successfully prepared by nucleophilic substitution method,with high synthesis efficiency(39.2%)and good specific activity(31 GBq/? mol).The quality of products was stable between different batches by quality detection.Abnormal toxicity text in mice convinced the safety of 18F-MyoZone application in vivo,which provided a favorable reference for further biological performance evaluation.Project 2 Mechanism of 18F-MyoZone in CardiomyocytesObjective:The purpose of this study is to investigate the mechanism of myocardial uptake and retention.Methods:A sequence of 19F-MyoZone solution was interacted with inhibited mitochondrial complex-I(MC-I).Myocardial tissue section of neonatal rat was inhibited firstly by 19F-MyoZone,19F-Flurpiridaz,rotenone and deguelin,or normal saline.18F-MyoZone was added for the autoradiography experiment to test whether 18F-MyoZone can bind with MC-I complex and the relevant binding activity.Separately,myocardial tissue section of neonatal rat incubated with rotenone or 19F-MyoZone and then added 18F-MyoZone solution to study the inhibition rate with autoradiography under different levels of inhibitors.In vitro,cardiomyocytes of rat were cultured and added different levels of 19F-MyoZone or equivalent rotenone.After lysing cells,photon counts were measured,and IC50 was calculated.Separately,cultured cardiomyocytes of rat were interacted with 18F-MyoZone to measure photon counts at time points of 0,10min,20min,30min,60min,90min,120min and 150min.The ratio of cell outflow rate was then calculated.Results:19F-MyoZone couled effectively inhibite the activity of MC-I enzyme with a dose dependence.The IC50 of 19F-MyoZone on MC-I enzyme activity was calculated to be 229.9nmol/L.Autoradiography study found that the myocardial tissue slices added with 19F-MyoZone or MC-I inhibitors(19F-Flurpiridaz,rotenone and acaridin,respectively)showed a reduction in the radioactive uptake of 19F-MyoZone,which conviced that 19F-MyoZone can interact with MC-I as its binding site that behaved as an inhibitor similar to rotenone,19F-Flurpiridaz and deguelin.In vitro cultured cardiomyocyte study showed that the radiation uptake of 19F-MyoZone was dose-dependent with the concentration of rotenone,the IC50 was 7nmol/L.Cardiomyocyte outflow experiment showed that cardiomyocytes of rat can uptake 18F-MyoZone and stay stably over time.Within 0-30 min,the outflow rate gradually increased and maintained constantly from 60 to 150 min.The retention was 20%of entire uptake.Conclusion:The vitro experiment demonstrated that 19F-MyoZone can be specifically reacted with MC-I in cardiomyocytes of rat.The retention time can be prolonged reaching 150 min.These characteristics allow 18F-MyoZone fast and sustained accumulation in the heart as an attractive myocardial perfusion agent.Project 3 PET imaging of 18F-MyoZone in AnimalsObjective:To study the tissue distribution of 18F-MyoZone in mini-swine,and to evaluate its potential as a PET myocardial perfusion imaging(MPI)agent.Methods:Approximately 3 mCi of 18F-MyoZone was injected into 6 mini-swines intravenously.The whole body PET scans were performed at 5 min,20min,40 min,60 min and 120 min after injection.Standardized Uptake Value(SUV)of organs,heart/liver and heart/lung SUV ratios were measured over time.PET/CT rest MPI was conducted in 3 healthy mini-swines at 5 min,20min,40 min,60 min and 120 min after 3 mCi of 18F-MyoZone injection.Three acute myocardial infarction mini-swines were prepared,and the rest MPI was performed as before.Three mini-swines with chronic myocardial ischemia were prepared,and ATP stress/rest MPI was performed as before.Results:In the biodistribution study of healthy mini-swines,18F-MyoZone showed a high initial heart uptake(SUV=10.40±2.40 at 5mm after injectioin)and remarkable heart retention within 120 min(SUV=9.20±2.00).The adjacent organs(like live and lung)indicated low uptake and rapid clearance.The heart/liver and heart/lung SUV ratios were 4.73 and 14.86 respectively at 5 min post-injection,with an increase to 11.20 and 20.67 at 120 min post-injection.Early significant uptake of radioactivity in the kidney was followed by rapid reduction,then the bladder gradually developped a concentration of radioactivity,which suggested that 18F-MyoZone is metabolized and excreted mainly through the urinary system.All PET images of MPI ware highly satisfactory within 5min-120min post-injection of 18F-MyoZone.In the MPI study of mini-swine,normal myocardium was clear with well-proportioned uptake,the infarct myocardium and severe ischemia myocardium performed defects,reversible defect by stress/rest MPI was observed in partially ischemia myocardium.Conclusion:PET/CT imaging of 18F-MyoZone exhibited high initial heart uptake,good stability and almost no interference from adjacent organs.Myocardial perfusioin imaging of 18F-MyoZone could not only display normal myocardium clearly,but also the ischemic myocardium and the infarcted myocardium could be well presented.Advantages in early imaging and wide diagnostic time window made 18F-MyoZone a promising myocardial perfusion agent. |
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