Preliminary Basic And Clinical Studies On Positron Emission Tomography

Alzheimer's disease, one of the most important causes of disability in the elderly, is a common neurodegenerative disorder characterized by the progressive degeneration of memory, and finally threats the life of patients. The disease has been a great burden to patients and their families, also to the communities, and has been the fourth disease to threat seriously the life of the elderly followed by heart disease,tumor and stroke. The prevalence of dementia among the elderly (aged 65 and over) in the western developed countries has been reported to be around 5-6%. With the increasing of the proportion of the elderly in China, the problem will become more and more serious. The study of prevalence of dementia in China dates from 1980's and the results were very different, and up to now there was still not a large-scale investigation. According to the data surveyed in the regions of 11 rural and urban in China, the prevalence of AD was 238 per 100,000 populations over 60 years old. It is estimated that the number of the dementia populalation in China aged 65 and over was more than 5,000, 000, which the prevalence was 10.1%, among which AD was 3,100,000 according to the relative experts introduced in the wrold dementia day in 2004 . Zhang Mingyuan et al has ever surveyed a community twice during five years in Shanghai, and showed that the incidence of AD was 0.89%(95%CI: 0.88% -1.42%). In order to pay more attention to the disease, it is urgent to focus on the dementia and should take action to change the situation.The effective elements of Chinese traditional medicine, such as ginsenosides, Huperzine-A and Sarsasapogenin (ZMS), has already been used to treat Alzheimer's disease, among which ZMS can significantly improve the learning and memory ability and increase the brain muscarinic receptor density of the model, and has get the inventive patent of China. The effective rate of ZMS (70. 8%) was higher than that of Huperzine-A in clinical experiment.The important application of positron radionuclide such as ¹⁸F, ¹¹C, ¹³N can reflect the physiological, biochemical, pathological process in vivo. If the effectiveelements of Chinese traditional herbs can be radiolabeled by the positron radionuclide, the study will be of significance and creativity because it can improve the development of the Chinese traditional pharmaceuticals. The purposes of the study were to explore the feasible method of positron radionuclide radiolabeling the effective element of Chinese traditional pharmaceuticals; to explore the method of ¹⁸F-radiolabeled the effective element (ZMS) of anemarrhena and its pharmacokinetics and distribution in vivo,and its mechanism of action in the brain of dementia animal model.Part â… . Synthesis and quality control of ¹⁸F-radiolabeled the effective element (ZMS) of anemarrhena (¹⁸F-FZMS)Objective: To expore the method and quality control of ¹⁸F-radiolabeled the effective element (ZMS) of anemarrhena (¹⁸F-FZMS). Methods: Firstly the tosyl-ZMS was synthesized. ZMS was dissolved in dry pyridine and sulfonyl chloride which was dissolved in dichloromethane was added with constant stirring in ice bath (0℃) for 2h and then at room temperature for 72h, and the tosyl-ZMS was checked by ¹H-NMR and MS. Radiolabeled product [¹⁸F] FZMS was prepared by fluorination of the tosyl-ZMS with [¹⁸F] KF and kryptofix 2.2.2. The labeled product was analyzed by HPLC on a reverse-phase C18 column, and eluted with 100% acetonitrile at a flow rate of 0.3 ml/min. Contents and analytical methods of quality control for ¹⁸F-FZMS were investigated and the main quality criteria were achieved through strict control of the determining parameters by standard procedures. Results: The tosyl — ZMS was obtained in 51.23% yield. Radiochemical yield was 20～44.11% with an average of 32% (corrected for decay). Synthesis time was 50 to 70 min with radiochemical purity >95%, and average specific activity of 69.3GBq/mmol. All quality criteria of ¹⁸F-FZMS met the requirements of the positron radionuclide-radiolabeled pharmaceuticals. Conclusion: ¹⁸F-FZMS injections can be used to further study in the animal or human study.Part â…¡. Pharmacokinetics and biodistribution of ¹⁸F-FZMS in the normal animalObjective: To exolpre the pharmacokinetics and biodistribution of the new agent, ¹⁸F-FZMS, in vivo. Methods: Take the sample of blood and organs in different time, 2 min, 5 min, 10 min, 15 min, 30 min, 60 min, 120 min, after injecting ¹⁸F-FZMS by vail in mice and measure the cpm, then the % ID/g was calculated. Analysed thepharmacokinetics by taking the blood sample from tail of rats and analysed the biodistribution in the different regions of brain such as cerebellum, brain stem , thalamencephalon, striatum, occipital lobe, apical lobe, hippcamp and temporal lobe in the rats. Results: ¹⁸F-FZMS is of the charicteristic that quickly discharge from the blood, which is 9.496±2.123%ID/g at 2 min and 0.146±0.041%ID/g at 60 min. Liver and kidney are the main organ to discharge the ¹⁸F-FZMS, especial in the liver and gallbladder system which is 28.923±4.357%ID/g at 2 min and decreasing graduately. Until 60 min the discharging of ¹⁸F-FZMS was keeping in a relative higher level and was 2.413±0.749%ID/g at 2min in kidney. Pharmacokinetics of ¹⁸F-FZMS in the rats corresponded to two-compartment model and C=1.895e ^-0.7567t+0.0169e^-0.0044t. The ditribution half-time T1/2α =0.9158min and clearance half-time (T1/2β)was T1/2 β =157.5min. Concisions: ¹⁸F-FZMS can quickly discharge and decrease to the low level from background of issues in vivo. There is no significant difference of ¹⁸F-FZMS that distribute in the different brain regions.Part â…¢.The preliminary exploring the distribution of ¹⁸F-FZMS in the brain of dementia rats by autoradiographObjective: To explore the distribution of ¹⁸F-FZMS in the brain of dementia rats by autoradiograph. Methods:The Aβ1-40 dementia model, aged rats (20month) and scopolamine model was established, and Morris Water Maze including place navigation and spatial probe tests were performed to measure the changes of the rats' learning and emory capacities. ¹⁸F-FZMS was evaluated in the brain of the dementia model by autoradiograph. Results: The rats' learning and memory capacities of the Aβ1-40 dementia model, aged rats and scopolamine model was decreased compared with control rats. Autoradiograph showed that there is no different PSL value in the brain of Aβ1-40 dementia model, aged rats and scopolamine model (F=1.04, P=0.4095>0.05, F=2.06, P=0.0753>0.05 and F=1.05, P=0.406>0.05, respectively). Conclusion: There is no specific brain region that uptake higher ¹⁸F-FZMS, and confirmed that the treatment mechanism of ZMS in a slowly process to treat dementia.Part â…£. The prevalence of dementia in Chinese people: a systematic analysis of 1985—2004 studyingObjectives: To explore prevalence of dementia in Chinese senile people from1985-2004 and provide evidence for decision-making. Methods: systematic analysis was performed to evaluate the data extracted from the papers published in 1985～2004 on the prevalence of dementia in China. Results: 22 papers were included, the prevalence of dementia for the senile people aged 60 and over was 2.818%, and that of Alzheimer's disease(AD) and vascular dementia(VD),which were two major types of dementia in China, was 1.587%, 0.756%, respectively. There was higher prevalence of AD in illiterate (3.160%) than those who have had received education; From 1985 to 2004 the prevalence of dementia and AD increased significantly, and was 5.727%, 4.805% respectively from 2001 to 2004; The prevalence of AD increased with aging and peaked in the group of senile population aged 90 and over (21.39%). The prevalence of dementia in southern China and northern China was 2.729%, 2.651%, respectively, and the prevalence of AD was 1.965%, 1.187%, respectively, VD was 0.570%, 1.036%, respectively. Conclusions: The prevalence of AD was associated with age, sex, education and occupation and difference of urban and rural, the prevalence of VD in northern China was higher.Conclusions( Part â…  -Part　Ⅳ):â‘  Synthesis of ¹⁸F-FZMS is of high radiochemical purity and good stability in vitro. All quality criteria of ¹⁸F-FZMS met the requirements of the positron radionuclide-radiolabeled pharmaceutical, and can be used to further study.â‘¡ ¹⁸F-FZMS can quickly discharge and decrease to the low level in vivo. Pharmacokinetics of ¹⁸F-FZMS in the rats corresponded to two-compartment model and there is no significant difference of ¹⁸F-FZMS that distributes in the different brain regions of both normal and dementia rats. And confirm that the mechanism of ZMS to treat dementia is in a slow progress.â‘¢The prevalence of AD were associated with age, sex, education and occupation and difference of urban and rural, and the prevalence of VD in northern China was higher and AD higher in southern China.