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Background and purpose:Integrinαvβ3 receptor plays an important role in promoting, sustaining and regulating the angiogenesis. It is overexpressed on neovascular endothelial cells and tumor cells. RGD peptide specifically binds to integrinαvβ3, which could evaluate growth status and invasiveness of tumor. This study aimed to investigate the biodistribution in healthy KM mice and micro PET/CT imaging in U87MG tumor-bearing mice of 18F-E[c(RGDfK)2]. Methods: 18F-E[c(RGDfK)2] was produced using an automated synthesis module via a simple one-step 18F-labeling strategy of the precursor 4-NO2-3-TFMBz-E[c(RGDfK)2]. The percentage activity of injection dose per gram of tissue (%ID/g) was calculated at 0.5, 1, 2, 4 h post injection of the probe. Micro PET/CT images of U87MG tumor-bearing nude mice with or without 18F-E[c(RGDfK)2] blocking were acquired at each time point. Results: The labeling efficiency and radiochemical purity of 18F-E[c(RGDfK)2] were 10% and 98%, respectively. 18F-E[c(RGDfK)2] was excreted via renal route, with a high blood clearance. The other organs had background-level activity accumulation. At 1 h, the%ID/g of kidney, liver, intestine, muscle and blood was (1.02±0.16)%ID/g,(0.24±0.06)%ID/g, (0.35±0.03)%ID/g, (0.13±0.03)%ID/g and (0.11±0.03)%ID/g 18F-E[c(RGDfK)2] had initial high tumor uptake [(5.2±0.56)%ID/g] and good tumor-to-background contrast (5.36) at 1 h post injection. Tumor uptake for blocking group was lower than those without blocking, and T/M reduced to 1.57. Conclusion: 18F-E[c(RGDfK)2] appears a promising PET molecular imaging probe targeting integrin αvβ3, with high tumor uptake. It could be suitable for prognosis evaluation of integrin-positive tumor, selection of vascular targeting therapy and therapy effect monitoring.
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Objective To investigate the application value of early evaluation and monitoring of 125Ⅰ interstitial implantation in a pancreatic cancer xeuograft.Methods Xenograft models were created by subcutaneous injection of Sw 1990 human pancreatic cancer cell suspensions into the right hind limbs of the immunodeficient BABL/c nude mice.The tumors size were about 8-10 mm after two weeks.The mice were randomly divided into 3 groups,including control group (n = 4) ,empty seed implantation group (n = 4)and 125Ⅰ implantation group (n = 4).Before treatment and one week after treatment,18F-FDG Micro-PET/CT scan was performed and then maximum standardized uptake values (SUVmax),mean standardized uptake values (SUVmean),tumor size and necrosis rate were measured.HE staining and TK1 immunohistochemistry examination were carried out in the paraffin-embedded sample.Results Before treatment the SUVmax and SUVmean values of three groups did not reach statistical significance.One week after treatment the SUVmax and SUV values of three groups were 3.53 + 1.20 and 0.57±0.26 vs.3.83±2.13 and0.59 ±0.24vs.0.29±0.23 and0.016±0.001,respectively,with a significant difference (F =7.62,P =0.01 ; F = 10.34,P =0.005).The SUVmax and SUVmean values of 125Ⅰ implant group were significantly lower than empty seed implant group and control group and were significantly lower than before treatment.Before treatment,tumor necrosis rate of three groups were not significantly different.Immunohistochemical staining found the TK1 positive staining index of three groups were respectively (64.25±1.71) % ,(62.25±2.22) % and (38.25±1.71) % with statistically significant difference (F =233.67,P < 0.001).The TK1 positive staining index of 125Ⅰ implant group was significantly lower than empty seed implant group and control group.The SUVmax values had some positive correlation with TK1 positive staining index (r = 0.85,P = 0.001).Conclusions 18F-FDG Micro-PET/CT may be useful as a noninvasive imaging modality to assess early response to 125Ⅰ seed brachytherapy in a pancreatic cancer xenograft.
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In conventional pharmacological research in the field of mental disorders, pharmacological effect and dose have been estimated by ethological approach and in vitro data of affinity to the site of action. In addition, the frequency of administration has been estimated from drug kinetics in blood. However, there is a problem regarding an objective index of drug effects in the living body. Furthermore, the possibility that the concentration of drug in blood does not necessarily reflect the drug kinetics in target organs has been pointed out. Positron emission tomography (PET) techniques have made progress for more than 20 years, and made it possible to measure the distribution and kinetics of small molecule components in living brain. In this article, we focused on rational drug dosing using receptor occupancy and proof-of-concept of drugs in the drug development process using PET.
Subject(s)
Brain , Central Nervous System , Drug Evaluation , Electrons , Kinetics , Mental Disorders , Norepinephrine Plasma Membrane Transport Proteins , Positron-Emission Tomography , Receptors, Dopamine D2 , Serotonin Plasma Membrane Transport ProteinsABSTRACT
Objective To explore the feasibility of detecting atherosclerosis with 7.0T MR and Micro-PET. Methods Ten 46-week-old ApoE-/- mice with high lipid diet for 6 months were selected to establish atherosclerosis models. Among them, 5 mice underwent MRI before and 12 h, 24 h, 36 h after injection of SPIO, respectively, and the other 5 mice were injected with ~(18)F-fluorodeoxyglucose (~(18)F-FDG) through tail vein and observed with Micro-PET after 1 h, 2 h and 3 h. The specimens of abdominal aorta were taken for pathologic examination. Results Atherosclerotic plaques were observed in all animals with 7.0T MRI after 6 months high lipid diet. Thirty-six hours after the injection of SPIO, the high signal rings were thinner and the lumen of blood vessels were wider than those before injection on T2WI. Radioactive concentration was observed in abdominal aorta and both sides of iliac artery 3 h after the injection of ~(18)F-fluorodeoxyglucose (~(18)F-FDG). Pathological examination showed the formation of atherosclerotic plaques and the aggregation of the macrophages. Conclusion 7.0T MRI and Micro-PET can be used to observe the macrophage-rich plaque and to judge the vulnerability of plaque, thus provide theoretical basis for early detection, diagnosis and treatment of atherosclerosis.