Feasibility of experimental BT4C glioma models for somatostatin receptor 2-targeted therapies

<div><p></p><p>Somatostatin receptor subtype 2 (sstr₂) is regarded as a potential target in malignant gliomas for new therapeutic approaches. Therefore, visualizing and quantifying tumor sstr₂ expression in vivo would be highly relevant for the future development of sstr₂-targeted therapies. The purpose of this study was to evaluate sstr₂ status in experimental BT4C malignant gliomas.</p><p><b>Methods.</b> Rat BT4C malignant glioma cells were injected into BDIX rat brain or subcutaneously into nude mice. Tumor uptake of [⁶⁸Ga]DOTA-(Tyr³)-Octreotide ([⁶⁸Ga]DOTATOC), a somatostatin analog binding to sstr₂, was studied by positron emission tomography/computed tomography (PET/CT). Additionally, subcutaneous tumor-bearing mice underwent PET imaging with 5-deoxy-5-[¹⁸F]fluororibose-NOC ([¹⁸F]FDR-NOC), a novel glycosylated peptide tracer also targeting sstr₂. Ex vivo tissue radioactivity measurements, autoradiography and immunohistochemistry were performed to study sstr₂ expression.</p><p><b>Results.</b> Increased tumor uptake of [⁶⁸Ga]DOTATOC was detected at autoradiography with mean tumor-to-brain ratio of 68 ± 30 and tumor-to-muscle ratio of 9.2 ± 3.8 for rat glioma. High tumor-to-muscle ratios were also observed in subcutaneous tumor-bearing mice after injection with [⁶⁸Ga]DOTATOC and [¹⁸F]FDR-NOC with both autoradiography (6.7 ± 1.5 and 4.3 ± 0.8, respectively) and tissue radioactivity measurements (6.5 ± 0.8 and 4.8 ± 0.6, respectively). Furthermore, sstr₂ immunohistochemistry showed positive staining in both tumor models. However, surprisingly low tumor signal compromised PET imaging. Mean SUV_max for rat gliomas was 0.64 ± 0.28 from 30 to 60 min after [⁶⁸Ga]DOTATOC injection. The majority of subcutaneous tumors were not visualized by [⁶⁸Ga]DOTATOC or [¹⁸F]FDR-NOC PET.</p><p><b>Conclusions.</b> Experimental BT4C gliomas show high expression of sstr₂. Weak signal in PET imaging, however, suggests only limited benefit of [⁶⁸Ga]DOTATOC or [¹⁸F]FDR-NOC PET/CT in this tumor model for in vivo imaging of sstr₂ status.</p></div

新疆额尔齐斯河流域蚊虫的高效安全防控技术及应用[C]

新疆北屯地区位于额尔齐斯河下游的河岸谷盆地区,昼夜温差大,紫外线强烈,每年春夏之交上游水闸泄水漫灌草地,造成大面积的坑洼积水,遍布农田的排碱渠和漫灌林带等水体为蚊虫的滋生提供了绝好的场所,使当地人民饱受蚊虫叮咬之苦