Characteristics of 99Tcm-MIBI hepatobiliary scintigraphy in biliary atresia model and its association with the expression of P-glycoprotein in intestinal tissues / 中华核医学与分子影像杂志

Objective To establish rat models of extrahepatic biliary atresia,and to observe the characteristics of 99Tcm-MIBI hepatobiliary scintigraphy and evaluate its association with the expression Pglycoprotein (P-gp) in intestinal tissues.Methods A total of 12 SD rats were randomly divided into the normal control group (3 rats) and the group of common bile duct ligation (CBDL;9 rats).CBDL was used to establish the rat model of extrahepatic biliary atresia.99Tcm-MIBI hepatobiliary scintigraphy was performed at 2,3 and 4 weeks after ligation in the CBDL group and normal control group with continuous dynamic acquisition (3 min/frame) for 30 min and then delaying imaging at 30 min,1,2 and 3 h.After that,all rats were sacrificed,and the blood samples were taken out for the determination of serum ALT,AST,TBIL,DBIL,IBIL,ALP,γ-GT and TBA,and the tissues of duodenum,jejunum,ileum,colon and cecum were taken out for analyzing the expression level of P-gp by immunohistochemistry.Two-sample t test and one-way analysis of variance were used.Results Compared with the normal control group,the serum levels of ALT,AST,TBIL,DBIL,IBIL,ALP,γ-GT and TBA were significantly increasing at 2,3,4 weeks after ligation in CBDL group (t:-3.04 to-44.54,all P＜0.05).99Tcm-MIBI hepatobiliary imaging showed that there was radioactive accumulation in colon or cecum area,excluding the duodenum,jejunum and ileum area,at 3 h after intravenous injection of 99Tcm-MIBI in CBDL group.The results of immunohistochemistry showed that with the obstruction time prolonged,the expression levels of P-gp in duodenum,jejunum and ileum segments were gradually decreased (F=5.17,9.07,23.52;all P＜0.05),while the expression levels in the colon and cecum segments were not changed obviously (F=2.00,3.17;both P＞0.05).Conclusion 99Tcm-MIBI can be excreted through intestinal mucosa,and this process may be associated with P-gp expression.

Effect of the two-step pretargeting radioimmunotherapy of CD45 monoclonal antibody and 188Re-Avidin on lymphoma Raji cell line / 中华放射医学与防护杂志

Objective To study the effect of two-step pretargeting radioimmunotherapy of CD45 McAb and 188Re-Avidin on lymphoma Raji cell line.Methods The CD45 McAb and Avidin were directly labeled with 188Re,and the labeling efficiency and radiochemical purity were measured by the paper chromatography.The specific binding test and competition binding test between 188 Re-CD45 McAb and Raji cells in vitro were also performed.CCK-8 assay was used to determine the inhibition effect on Raji cell proliferation in the pretargeted group,188Re-CD45 McAb,188Re-Avidin and 188ReO4 groups,then the cell survival and proliferation inhibition rate were calculated.Results The specific cell binding rate of 188Re-CD45 McAb with Raji cells was (70.92 ± 1.91) ％,in the competition group,the binging rate of 188Re-CD45 McAb with Raji cells was only (7.96 ± 0.87)％.The Raji cells proliferation was inhibited in all groups with 188Re radiolabel,and the inhibition rate was positively correlated with the radioactivity dose (r=0.907-0.992,P ＜0.05).However,at the same dose,the inhibition effect in the group of two-step pretargeting at each time point were all stronger than those of 188Re-CD45 McAb,188Re-Avidin and 188 ReO4-alone (t =124.76-607.98,P ＜ 0.05).But there was no significantly statistical difference in the inhibitory effect between the groups of 188Re-Avidin and 188ReO4-(P ＞ 0.05).Conclusions It is confirmed that 188Re-CD45 McAb could be specifically bound to Raji cells,and the two-step pretargeting of CD45 McAb and 188Re-Avidin has obvious inhibitory effect on the Raji cell proliferation.

Radioimmunoimaging of lymphoma in mice with a two-step pretargeting strategy using biotinyled CD45 monoclonal antibody and (188)Re-avidin / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a two-step pretargeting approach to lymphoma radioimmunoimaging in mice using biotinynaled CD45 monoclonal antibody (McAb) and (188)Re-avidin in a tumor-bearing mouse model.</p><p><b>METHODS</b>Six Nod-Scid mice bearing lymphoma cell xenograft were randomized to receive either an intravenous injection of 50 µg/200 µL biotinyled CD45 McAb followed 24 h later by an intraperitoneal injection of 3.7 MBq (50 µg/100 µL) (188)Re-avidin (two-step pretargeting group), or a single intravenous injection of 3.7 MBq (100 µg/100 µL) (188)Re-CD45 McAb (control group). SPECT was performed at 0.5, 1, 6 and 23 h post-injection to characterize (188)Re isotope biodistribution. At 24 h pos-injection, the mice were sacrificed for measurement of radioactivity uptake in the tumor and normal tissues and calculation of the tumor-to-non-tumor (T/NT) ratios.</p><p><b>RESULTS</b>SPECT showed that the two-step pretargeting method resulted in a low radioactivity in the blood pool during the imaging and a concentrated radioactivity in the liver and spleen. The transplanted tumor began to be displayed at 1 h post-injection and was clearly displayed at 1-6 h; the images were clear even at 23 h. With the two-step pretargeting method, the radioactive uptake at 24 h post-injection were (1.34∓0.52)%, (6.77∓2.32)%, and (2.81∓1.25)% in the tumor, kidney and liver, respectively, with low radioactivity levels in other organs and high tumor/blood and tumor/muscle ratios (4.28∓0.82 and 8.00∓0.88, respectively). In the control group, SPECT revealed intense radioactivity in the liver, spleen, and kidneys with obscure display of the tumor; at 20 h, the radioactivity in the blood pool remained high but that in the tumor was low, and the tumor/blood and tumor/muscle ratios at 24 h were only 0.58∓0.06 and 3.21∓0.24, respectively.</p><p><b>CONCLUSION</b>Compared with (188)Re-CD45 McAb, the two-step pretargeting approach exhibits a good specificity in targeting lymphoma with an increased T/NT ratio in mice and allows early tumor display at 1 h post-injection.</p>

Radiolabelling of a lung cancer-targeting small molecule polypeptide with (131)I and its radioactivity distribution in normal rabbits / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a labeling method for a specific lung cancer-targeting small molecule peptide cNGQGEQc with ¹³¹I and observe the radioactivity distribution of the labeled peptide in rabbits using single-photon emission computed tomography (SPECT).</p><p><b>METHODS</b>Chloramine-T method was used for ¹³¹I labeling of the tyrosine amino group on cNGQGEQc, and the labeling efficiency and radiochemical purity of ¹³¹I-cNGQGEQc were determined with paper chromatography. The stability of ¹³¹I-cNGQGEQc in saline and human serum was assessed after incubation in water bath at 37 degrees celsius; for 24 h. The octanol-water partition coefficient lg P (the radioactivity counting ratio of ¹³¹I-cNGQGEQc dissolved in 100 µl octanol or in 100 µl saline) was calculated. SPECT was performed in 3 male New Zealand white rabbits after intravenous injection of ¹³¹I-cNGQGEQc to observe the dynamic distribution of the peptide with the time-radioactivity curve (T-A curve) of the region of interest (ROI).</p><p><b>RESULTS</b>With a labeling efficiency of 90%, ¹³¹I-cNGQGEQc showed a radiochemical purity of was 95% after purification with HPLC. The radiochemical purity of ¹³¹I-cNGQGEQc was (93.12 ± 1.18)% and (88.34 ± 5.43)% after intubation in saline and human serum for 24 h, respectively. The octanol-water partition coefficient lg P of ¹³¹I-cNGQGEQc was -1.75, suggesting its hydrosolubility. In rabbits with intravenous injection of ¹³¹I-cNGQGEQc, SPECT visualized the kidneys at 1 min after the injection; the imaging of the heart and liver became attenuated at 5 min when the bladder was visualized with an increasing radioactivity. The radioactivity of the soft tissues began to fade at 30 min. No gallbladder visualization was detected, and the radioactivity of the abdomen remained low. No obvious radioactivity concentration was observed in the thyroid and stomach. The T-A curves of the ROI of all the tissues and organs descended over time.</p><p><b>CONCLUSION</b>Radiolabeling of cNGQGEQc with ¹³¹I is simple and highly efficient. ¹³¹I-cNGQGEQc has good stability in vitro and good distribution characteristics for in vivo imaging, and is cleared mainly by renal excretion due to its hydrosolubility. These results provide experimental basis for further studies of diagnosis and therapy of lung cancer with targeting polypeptide.</p>

(99m)Tc radiolabeling of a novel polypeptide molecular probe for lung cancer and its biodistribution in animals / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a method for (99m)Tc radiolabeling of a small molecular peptide targeting lung carcinoma and observe the biokinetics and biodistribution of the labeled peptide in normal mice and rabbits.</p><p><b>METHODS</b>MAG3-peptide (cNGQGEQc) was labeled with (99m)Tc and the labeling rate was determined with paper chromatography. In vitro stability test, cysteine challenge test and serum incubation test were performed for radiochemical evaluation of the labeled peptide. Blood (99m)Tc-peptide clearance in rabbits was evaluated by determining blood radioactive concentrations at different time points after injection of 37 MBq (99m)Tc-peptide, and its dynamic distribution was investigated by SPECT imaging. The percent injected dose per gram of tissue was calculated for each organ of mice injected intravenously with 7.4 MBq (99m)Tc-peptide based on gamma counter readings.</p><p><b>RESULTS</b>The labeling rate of (99m)Tc-peptide exceeded 90%, and the radiochemical purity was 91% after placing for 12 h at room temperature and 85% after incubation at 37 degrees celsius; with human serum. The cysteine replacement rate was less than 7%, and the binding rate of (99m)Tc-peptide with serum proteins was below 5%. SPECT imaging showed that the labeled peptide could be quickly cleared from the blood in normal animals primarily through the kidneys, and the radioactivity in other tissues and organs remained low.</p><p><b>CONCLUSION</b>(99m)Tc-peptide can be easily prepared with a high labeling yield. With good stability both in vitro and in vivo, (99m)Tc-peptide can be quickly cleared from the blood and excreted though the kidney with ideal biodistribution and biokinetics in vivo.</p>