Enhanced radiation damage caused by iodinated contrast agents during CT examination.

OBJECTIVE: To access the effect of iodinate contrast agent (ICA) on DNA double-stand breaks (DSBs) in human peripheral blood lymphocytes during computed tomography (CT) examinations. MATERIALS AND METHODS: This present study was approved by the institutional ethics committee; written informed patient consent was obtained from 70 patients. A total of 48 patients underwent computed tomography urography (CTU), in which only one time CT scanning was examined after injecting ICA, and 22 patients received unenhanced whole abdominal CT, among them 10 patients were selected to get ICA injection immediately after irradiation. Blood samples were taken from all patients prior to and immediately after CT scan, as well as 8min after the injection of ICA. The lymphocytes in these blood samples were separated by using density-gradient centrifugation, fixed and immunostained with γH2AX antibody. The average number of phosphorylated histone H2AX (γH2AX) foci per lymphocyte was counted under a fluorescence microscopy. Differences in the number of γH2AX-foci were statistically analyzed using independent sample t test and one way ANOVA. RESULT: The three patient groups had no significant differences in the baseline foci numbers(P>0.05). The γH2AX-focus levels increased in both groups after CT scan. Patients who underwent CTU examinations had a greater DSBs level (mean±standard error of mean, 0.945±0.184 foci per cell) than those who received unenhanced whole abdominal CT scan (mean±standard error of mean, 0.700±0.112 foci per cell), increasing by about 37.9%; The ICA injected before CT scan itself had an effect on the DSBs, which increased DSBs level by approximately 90.3% (0.059±0.018vs 0.031±0.025, P<0.05), but no significant difference was found if added after irradiation, increasing DSBs level only by 3.2% approximately (0.711±0.091vs 0.689±0.108, P=0.499). CONCLUSION: The iodinated contrast agent itself can lead to an increase in the level of DSBs as assessed with γH2AX foci formation, and the application of ICA can amplify DNA damage induced by diagnostic x-ray procedures such as whole abdominal CT.

Lack of association of common polymorphisms in MUC1 gene with H. pylori infection and non-cardia gastric cancer risk in a Chinese population.

Several lines of evidence support the notion that MUC1 is often aberrantly expressed in gastric cancer, and it is a ligand for Helicobacter pylori. Genetic variation in MUC1 gene may confer susceptibility to H. pylori infection and gastric cancer. We assessed the association of common polymorphisms in MUC1 gene with H. pylori infection and non-cardia gastric cancer using an LD-based tag SNP approach in north-western Chinese Han population. A total of four SNPs were successfully genotyped among 288 patients with non-cardia gastric cancer and 281 age- and sex-matched controls. None of the tested SNPs was associated with H. pylori infection. SNP rs9426886 was associated with a decreased risk of non-cardia gastric cancer, but lost significance after adjustment for multiple testing. Overall, our data indicated that common genetic variations in MUC1 gene might not make a major contribution to the risk of H. pylori infection and non-cardia gastric cancer in our studied population.