分类: 生物学 >> 生物物理学 提交时间: 2016-05-05
摘要: We have designed and synthesized a series of cyclopentadienyl tricarbonyl rhenium complexes containing a 5,6-dimethoxyisoindoline or a 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline pharmacophore as sigma(2) receptor ligands. Rhenium compound 20a possessed low nanomolar sigma(2) receptor affinity (K-i = 2.97 nM) and moderate subtype selectivity (10-fold). Moreover, it showed high selectivity toward vesicular acetylcholine transporter (2374-fold), dopamine D-2L receptor, NMDA receptor, opiate receptor, dopamine transporter, norepinephrine transporter, and serotonin transporter. Its corresponding radiotracer [Tc-99m]20b showed high uptake in a time- and dose-dependent manner in DU145 prostate cells and C6 glioma cells. In addition, this tracer exhibited high tumor uptake (5.92% ID/g at 240 min) and high tumor/blood and tumor/muscle ratios (21 and 16 at 240 min, respectively) as well as specific binding to sigma receptors in nude mice bearing C6 glioma xenografts. Small animal SPECT/CT imaging of [Tc-99m]20b in the C6 glioma xenograft model demonstrated a clear visualization of the tumor at 180 min after injection.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-05
摘要: We describe herein dual-modality imaging of intraperitoneal colon tumor using an avidin/biotin pretargeting system. A novel dual-modality probe,Tc-99m-HYNIC-lys(Cy5.5)-PEG4-biotin,was designed, synthesized and characterized. Single-photon emission computed tomography/computed tomography (SPECT/CT) imaging and near infrared fluorescence (NIRF) imaging were developed using intraperitoneal LS180 human colon adenocarcinoma xenografts. Following avidin preinjection for 4 hours, 99mTc-HYNIC-lys(Cy5.5)-PEG4-biotin could successfully detect colon tumors of different sizes inside the abdominal region using both modalities, and the imaging results showed no differences. Biodistribution studies demonstrated that the tumors had a very high uptake of the probe (TcHYNIC)-Tc-99m-lys(Cy5.5)-PEG4-biotin(12.74 +/- 1.89% ID/g at 2 h p.i.), and the clearance from blood and other normal tissues occured very fast. The low tumor uptake in the non-pretargeted mice (1.63 +/- 0.50% ID/g at 2 h p.i.) and tumor cell staining results showed excellent tumor binding specificity of the pretargeting system. The ability of the novel probe to show excellent imaging quality with high tumor-to-background contrast, a high degree of binding specificity with tumors and excellent in vivo biodistribution pharmacokinetics should prove that the avidin/biotin based dual-modality pretargeting probe is a promising imaging tool during the entire period of tumor diagnosis and treatment.