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Background C-X-C motif chemokine receptor 4 (CXCR4) plays a prominent role in inflammation, atherosclerosis, and cancer biology. Therefore, CXCR4 represents a promising target for molecular imaging in cardiovascular diseases such as atherosclerosis and arterial wall injury. CXCR4 and its cognate ligand, stromal cell–derived factor 1α (SDF-1α), induced monocyte recruitment to the injured endothelium and subsequent plaque formation is the crucial progression of atherosclerosis. CXCR4 was been proved to be intensively expressed on monocytes/macrophage. [68Ga]-APD, based on the structure of CXCR4 antagonists TIQ-15, had designed by computer simulation as a PET tracer for imaging activated macrophages within the atherosclerotic lesions. The aim of this study was to evaluate the biological characteristics of [68Ga]-APD, and compared with the PET tracers targeting atherosclerotic lesion such as [18F]-FDG, [18F]-NaF, and [68Ga]-Pentixafor in apolipoprotein-E-deficient (ApoE−/−) mice. Results The specification and quality of APD was identified by Mass, NMR and HPLC. After being labeled with Ga-68 under acetate buffer (pH≒5.5), radiochemical purity was over 90% and stable for more than 4 hours in 37℃human serum. After being injected from tail vein on ApoE−/− atherosclerotic mice model, hydrophilic [68Ga]-APD was quickly eliminate from the kidney and bladder. [68Ga]-APD could accumulate in the atherosclerotic aorta site and CXCR4 expression organs. The highest target/background ratio (TBR) on atherosclerotic sites were 17.68 ± 0.71 (n = 3) on high-fat diet ApoE−/− mice for 12 weeks after [68Ga]-APD injection within 1 hour. However, [68Ga]-Pentixafor was only 2.06 ± 0.67 (n = 3) on the same mice model. Competitive study represented that CXCR4 antagonist AMD3465 could effectively block the uptake of [68Ga]-APD on the atherosclerotic site and CXCR4 expression organs. Comparing with [18F]-FDG and [18F]-NaF, [68Ga]-APD represented relatively better TBR and specificity on the imaging of atherosclerotic lesions. Conclusion In vivo evaluation of CXCR4 expression in ApoE−/− mice revealed the uptake of [68Ga]-APD mainly accumulated in the atherosclerotic aorta site. Moreover, the TBR of [68Ga]-APD was 8 times higher than [68Ga]-Pentixafor, a radiotracer targeting CXCR4 and under phase II clinical trial, indicating this novel tracer [68Ga]-APD is more feasible as a surrogate marker for inflammatory atherosclerosis.

// Kai-Lin Yang 1, 2, 3 , Cheng-Chung Huang 1 , Mau-Shin Chi 1 , Hsin-Chien Chiang 1 , Yu-Shan Wang 1 , Chien-Chung Hsia 4 , Gabor Andocs 5 , Hsin-Ell Wang 2 , Kwan-Hwa Chi 1, 2, 6 1 Department of Radiation Therapy and Oncology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan 2 Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan 3 School of Medicine, Fu Jen Catholic University, New Taipei, Taiwan 4 Institute of Nuclear Energy Research, Taoyuan, Taiwan 5 Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Japan 6 Institute of Veterinary Clinical Science, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan Correspondence to: Kwan-Hwa Chi, email: M006565@ms.skh.org.tw Hsin-Ell Wang, email: hewang@ym.edu.tw Keywords: modulated electro-hyperthermia, conventional capacitive coupling hyperthermia, water bath, cytotoxicity, cell membrane Received: May 03, 2016 Accepted: August 11, 2016 Published: August 20, 2016 ABSTRACT Radiofrequency-induced hyperthermia (HT) treatments for cancer include conventional capacitive coupling hyperthermia (cCHT) and modulated electro-hyperthermia (mEHT). In this study, we directly compared these methods with regard to in vitro cytotoxicity and mechanisms of action under isothermal conditions. Hepatoma (HepG2) cells were exposed to HT treatment (42°C for 30 min) using mEHT, cCHT or a water bath. mEHT produced a much higher apoptosis rate (43.1% ± 5.8%) than cCHT (10.0% ± 0.6%), the water bath (8.4% ± 1.7%) or a 37°C control (6.6% ± 1.1%). The apoptosis-inducing effect of mEHT at 42°C was similar to that achieved with a water bath at 46°C. mEHT also increased expression of caspase-3, 8 and 9. All three hyperthermia methods increased intracellular heat shock protein 70 (Hsp70) levels, but only mEHT greatly increased the release of Hsp70 from cells. Calreticulin and E-cadherin levels in the cell membrane also increased after mEHT treatment, but not after cCHT or water bath. These results suggest that mEHT selectively deposits energy on the cell membrane and may be a useful treatment modality that targets cancer cell membranes.

Purpose: Several studies have reported significant renal toxicity after the use of a high dose of90Y-DOTATOC. Thus, renal protection is necessary in treatments with90Y-DOTA Tyr3-octroetide (DOTATOC). The infusion of certain positively charged amino acids has been shown to effectively reduce renal uptake of DOTATOC. In this study, we compared the effectiveness of three kinds of amino acids, D-lysine (lysine),L-arginine (arginine) and histidine, on renal protection in healthy rats and tried to determine which one was the most effective.Methods: Twenty SD healthy male rats were divided into 4 groups: lysine, histidine, arginine, and control. The rats were injected with a dose of 400 mg/kg of amono acid or 2 ml of phosphate-buffered saline (PBS) (as control) intraperitoneally. All rats were sacrificed at 4 hrs after the injection of 1 MBq111In-DOTATOC. Samples of the kidney were taken and weighed carefully. The counts of radioactivity were measured by a gamma counter and renal concentrations were calculated and expressed as percent injected dose per gram (% ID/g).Results: The renal uptake of111In-DOTATOC was significantly lower for all three kinds of amino acids when compared to the control group. The renal uptake of111In-DOTATOC in the lysine group was significantly lower than those in the histidine and arginine groups. The renal uptake of111In-DOTATOC in the histidine group was lower than that in the arginine group, but no statistical difference was noted.Conclusion: Among these three amino acids, lysine had the best reduction rate of renal uptake of DOTATOC. Histidine was more effective than arginine but no statistical difference was noted.

111In-DTPA octreotide (DTPAOC) has been used for detecting somatostatin receptor positive tumor for years. In-111 DOTA-Tyr3-octreotide (DOTATOC) is newly developed for diagnostic and therapeutic purposes. In this study, we compared the biodistribution and tumor uptake ratio after injection of In-111 DTPAOC and In-111 DOTATOC in rats. Twelve rats bearing pancreatic tumors were divided into two groups: six rats were sacrificed at 4 hr after injection of 3.7 MBq of In-111 DTPAOC and another 6 rats were sacrificed at the same time after injection of 3.7 MBq of In-111 DOTATOC. Samples of various organs were obtained and counted to calculate the tissue concentration. In addition, 12 rats bearing pancreatic tumors were scanned at 4, 24, and 48 hr after injection of 37 MBq of In-111 DTPAOC or In-111 DOTATOC. The tumor uptake ratios (T/N ratio) were calculated. The biodistribution data showed that the activity in the tumor as well as in the kidney was significantly higher in the In-111 DOTATOC group than in the In-111 DTPAOC group, although both radiopharmaceuticals had the expected high affinity to the tumor. The T/N ratios in the In-111 DOTATOC group were also significantly higher than those in the In-111 DTPAOC group at 24 hr after injection. We conclude that In-111 DOTATOC showed lower clearance than In-111 DTPAOC in the rats bearing pancreatic tumors, although both of these radiopharmaceuticals showed expected high tumor uptake.