Two hours after injection of 0.2 ml of the prepared 99mTc-HYNIC annexin (4-8 MBq), whole body planar imaging was performed on tumor bearing mice which had received different single-doses of radiation. As shown in Figures 2 and 3, without radiation (0 Gy), the radioactivity uptake in EL4 lymphoma and S180 sarcoma was GSK458 purchase similar to that of the background; the tumors were not clearly

shown in99mTc-HYNIC-annexinV imaging. Moreover, the images in control animals (0 Gy) demonstrated a high concentration of radio-labelled annexin V in the heart and bladder, with a lesser distribution in other organs (Figures 2A and 3A). The tracer uptake shows accumulation in the head and neck and thymus region in EL4 lymphoma irradiated with 4 Gy and 8 Gy (Figures 2C and 2D). The increased density of tracer in the tail (Figures 2A and 3B) was due to the tracer at Selleckchem MLN0128 the site of injection. The liver and kidneys were not visualized as separate structures. It demonstrated

(Figures 2B to 2D) that for EL4 lymphoma, as the radiation dose was escalated from 2 to 4 and 8 Gy, there was a marked increase in tumor uptake of99mTc-HYNIC annexin V. The irradiated tumor image became clearer. However, in S180 sarcoma bearing mice, even with 8 Gy irradiation, the tumor uptake of99mTc-HYNIC- annexin V was similar to that of the background; and the tumor was not clearly shown in imaging. The99mTc-HYNIC- annexin V uptake concentration was high in bladder, liver and kidney. Figure 2 Representative 99m Tc-HYNIC-annexin V scintigraphy (TAVS) images of EL4 lymphoma bearing mice treated with irradiation. Mice were injected 4-8 MBq radiolabeled annexin V 24 hours post-radiation and imaged 2 h later. The images Erastin supplier show increased annexin V uptake in tumor as radiation dose increased. The white arrow indicates the implanted tumor. A: 0 Gy; B:2 Gy; C:4 Gy; D:8 Gy. Figure 3 Annexin V imaging of S180 sarcoma bearing mice treated with

irradiation. The images show insignificant annexin V uptake in tumor with radiation dose of 8 Gy comparing to 0 Gy control. The white arrow indicates the implanted tumor. A: 0 Gy; B:8 Gy. Biodistribution of99mTc-HYNIC- annexin V and tumor apoptosis after irradiation The control and irradiated mice were sacrificed immediately after99mTc-HYNIC-annexin V imaging. Biodistribution assays were performed with a well-type γ-counter. The radioactivity parameters measured (T/M and T/B ratios) are shown in Tables 2 and 3. Table 2 Biodistribution of99mTc-HYNIC-Annexin-V in EL4 lymphoma and the number of apoptotic cells after single-dose irradiations     Dose (Gy)     p     0 2 4 8 0 vs.2 2 vs.4 4 vs.8 %ID/g 0.160 ± 0.013 0.272 ± 0.021 0.312 ± 0.020 0.355 ± 0.025 <0.001 0.017 0.009 T/B 0.729 ± 0.037 1.252 ± 0.086 1.396 ± 0.021 1.661 ± 0.072 <0.001 0.005 <0.001 T/M 2.575 ± 0.154 4.522 ± 0.554 5.191 ± 0.511 7.138 ± 0.266 <0.001 0.039 <0.001 Apoptotic cells 1.405 ± 0.191 2.459 ± 0.370 4.364 ± 0.778 6.