Based on an overreview of Chinese radiological health standards, the Chinese radiological health standards currently in effect for biodosimetry were analyzed with respect to their current status, application and existing problems. Furthermore the improvement measures and development trends were put forward.

Objective:To study the influence of circular RNA hsa_circZDHHC21_004 on the proliferation of human small intestinal epithelial cells HIEC-6 after 60Co γ-rays exposure. Methods:HIEC-6 cells were exposed to 60Co γ-rays at 0, 5, 10, and 15 Gy with a dose rate of 1 Gy/min. The expression level of hsa_circZDHHC21_004 in the irradiated HIEC-6 cell was detected. Hsa_circZDHHC21_004 was knocked-down to investigate the influences of hsa_circZDHHC21_004 on the proliferation of irradiated HIEC-6 cells by CCK-8 assay and colony formation assay. Results:The expression level of hsa_circZDHHC21_004 in HIEC-6 cells was upregulated by (1.00±0.24), (1.34±0.28), (1.85±0.31), and (2.80±0.64) times of control after 0, 5, 10, and 15 Gy irradiation, respectively and there were significant difference between 10 or 15 Gy group and 0 Gy group ( F=10.86, P=0.008). Knockdown of hsa_circZDHHC21_004 significantly increased the proliferation rate of HIEC-6 cells at 24, 48, and 72 h after 10 Gy irradiation compared with non-irradiated control ( t=-6.25, -5.83, -7.75, P < 0.001). Under 2 and 5 Gy irradiation, the clone formation rates of the hsa_circZDHHC21_004 knockdown cells were significantly higher than those of the control ( t=-7.45, -8.83, P<0.01). Conclusions:Hsa_circZDHHC21_004 is increased after irradiation and influenced the proliferation of irradiated HIEC-6 cells.

Objective:To explore the characteristics of lipid metabolism in rat plasma after total body irradiation(TBI) in order to provide scientific evidence of radiation biomarkers.Methods:For the non-targeted lipidomics study, 50 SD rats were divided into 6 groups and irradiated with 0, 1, 2, 3, 5 or 8 Gy 60Co γ-rays, respectively. For the targeted lipidomics study, 25 rats were divided into 5 groups and irradiated with 0, 0.5, 2.5, 4 or 6 Gy. Venous blood samples were collected and plasma were separated 4 h after TBI. Radiation-sensitive lipids were screened and their concentrations were determined. Receiver operating characteristic curve (ROC) and dose-response were analyzed. Results:A total of 15 radiation differential lipids were screened out based on non-targeted lipidomics study and 7 of them were identified as radiosensitive lipids by targeted lipidomics analysis. The ROC of radiosensitive lipids distinguished area under curve (AUC) of samples in 0 Gy group and > 0 Gy group, < 2 Gy group and ≥ 2 Gy group were all > 0.75. The AUC values were increased to 0.96 and 0.94 after the panel of radiation sensitive lipids ROC analysis. The concentrations of LysoPC(18: 2), LysoPC(22: 0), PC(18: 0/18: 2), PE(18: 2/16: 0) and PE(18: 2/18: 0) decreased with irradiation dose within 0-6 Gy.Conclusions:A total of 7 plasma radiosensitive lipids in rat plasma were identified 4 h after TBI, and the panel of them could be used for specific dose classification. Five of the lipids had good dose-response relationship.

Objective:To explore the influence of dose-rate on radiation-induced gene expression in human peripheral blood.Methods:Human peripheral blood ex vivo was irradiated with 0, 1, 2, 4 and 6 Gy of 60Co γ-rays with different dose-rates of 0.2, 1 and 2 Gy/min. Human blood cells were harvested at 24 h post-irradiation. Following RNA isolation, the mRNA expression levels ofCDKN1A, MDM2, PCNA, FDXR, GADD45A, PHPT1, ASTN2, TNFSF4, POLH, GDF-15 and PPM1D were measured by quantitative real-time PCR. The stepwise regression method was used to establish the gene combination models. Results:The relative mRNA expression levels of 11 genes significantly increased in a dose-dependent manner within the dose range of 0-6 Gy with three dose-rates of irradiation ( R2=0.744-0.998, P< 0.05). Following the exposure to 2 Gy(0.2 Gy/min) 60Co γ-rays, the expression levels of CDKN1A, FDXR, PHPT1 and TNFSF4 genes were significantly higher than that of the 1 and 2 Gy/min groups ( t=3.73, 5.73, 2.44, 2.77, 3.53, 2.68, 2.43, 2.05, P< 0.05). With 6 Gy irradiation, the changes of radiation-induced PPM1D expression level under a dose rate of 2 Gy/min were significantly higher than other two dose-rates( t=3.82, 2.54, P< 0.05). The combined expression model at different dose rates was composed of 2-3 genes, and the R2values of regression equations were 0.976, 0.964 and 0.951, respectively. Conclusions:In a certain range, the dose-rate may affect the changes of radiation-induced gene expression in human peripheral blood.

Objective:To screen radiosensitive lipid metabolites in rat small intestine and analyze their metabolic pathways, in order to provide scientific basis for radiation enteropathy biomarkers.Methods:The total body irradiation of 60Co γ rays was performed to rats with different doses of 0, 1, 2, 3, 5 and 8 Gy. The changes of lipids in small intestine were studied by targeted lipidomics method based on liquid chromatography coupled mass spectrometry (LC-MS). Results:Fifteen lipids in small intestine were screened as radiosensitive metabolites at 3 d after irradiation, including 4 up-regulated lipids and 11 down-regulated lipids( t=-6.395, 5.998, 5.836, -5.503, -5.449, -5.422, 4.841, 4.802, 4.621, 4.457, 4.426, 4.373, 4.110, 3.945, 3.902, P< 0.05 and FDR < 0.05). The metabolic pathways of sphingolipid, glycerophosphoplipid were significantly enriched. Four phosphatidyl serines (PS)increased while 1 phosphatidic acid(PA), 2 sphingomyelins(SM) and 4 fatty acids(FA)decreased in a good dose-response manner( R2> 0.80, P< 0.05), which were more potential radiation enteropathy biomarkers. Conclusions:Lipid metabolites in rat small intestine were significantly changed after the rat was total body irradiated with 60Co γ-rays.Eleven lipids with good dose-response relationship were more potential to be radiation enteropathy biomarkers.

Objective:To explore the feasibility of the optimized cytokinesis-block (CB) assay on radiation-induced nucleoplasmic bridge (NPB), and to provide a scientific basis for the application of NPB in biological dose estimation.Methods:Human peripheral blood in vitro was irradiated with 2 Gy 60Co γ-rays at a dose rate of 1 Gy/min (0 Gy control group). According to the culture time after irradiation, blood samples were divided into group 48, 56, 68 and 72 h. Cytochalasin-B (Cyt-B) with a concentration of 6 μg/ml was added into the samples at 28 h and harvested at 48, 56, 68 and 72 h after irradiation, respectively. On the other hand, the blood samples were treated with different concentration of Cyt-B i. e., 0.6, 1, 2, 6 and 10 μg/ml at the beginning of culture (0 h) and harvested at 68 h after irradiation. The proportion of mononucleated, binucleated and multinucleated cells, radiation-induced NPB and micronucleus (MN) frequencies were analyzed. Results:The nuclear division index (NDI) and proportion of binucleated cells at 2 Gy and 0 Gy had tendency of increasing with cell culture time. NPB frequencies (0.023 0-0.033 0/cell) and MN frequencies had no significantly difference ( P> 0.05). With the increase of Cyt-B concentration, NDI and the proportion of binucleated cells in group 2 Gy and 0 Gy also increased, but NPB frequencies (0.023 0-0.047 0/cell) had no significant difference ( P> 0.05). MN frequencies of group 10 μg/ml were significantly lower than that of group 6 μg/ml ( U=2.74, P< 0.01). Conclusions:Cell culture time and Cyt-B concentration had no significant influence on radiation-induced NPB frequencies, suggesting that NPB could be obtained by appropriately reducing cell culture time and Cyt-B could be added into blood samples at the beginning of culture. But this protocol reduced the number of cells for further analysis, and thus its feasibility for dose estimation still need to be studied.

Objective: To study the effects of sex, age, length of service, type of work and annual effective radiation dose on nucleoplasmic bridge (NPB) in the peripheral blood lymphocytes of radiation workers. Methods: The peripheral blood samples of 100 radiation workers in Henan province were collected and the NPB in peripheral blood lymphocytes were measured by CBMN assay. The frequencies of NPB formation and NPB-containing cells were calculated, and the effects of various factors on NPB incidence were analyzed statistically. Results: The NPB frequency in radiation workers was higher than that in healthy people (Z=-8.123, P<0.01). Except for sex, the factors of age, length of service, type of work and annual effective dose had significant influences on NPB (χ²= 7.202-45.571, P<0.05). Conclusions NPB reflects the effect of low-dose long-term chronic irradiation on the occupational radiation workers.

Objective:To screen the indicators of retrospective dose estimation, based on 5 cytogenetic methods to assess the victim followed-up at 4 year after 192Ir radiation accident in Nanjing. Methods:The chromosome aberration (dic + r) assay, cytokinesis block micronucleus (MN) and nucleoplasmic bridge (NPB) assay, fluorescence in situ hybridization (FISH)-based and G banding-based translocation analysis were used to retrospective biological dose estimation. Results:The estimated doses of FISH-based and G banding -based analysis were 1.45 and 1.21 Gy respectively, which was similar to the biological dose estimated short time after the accident. However, the estimated doses by chromosome aberration, micronucleus and nucleoplasmic bridge method were 0.56, 0.45 and 0.41 Gy respectively, which were lower than the corresponding biodose. Correction factors were used to adjust the biodose.Conclusions:In the 4th years after exposure, the estimated biological doses by FISH-based and G banding-based translocation were consistent with the biodose.Therefore, the two methods were suitable for retrospective dose estimation, while correction factors should be considered in chromosome aberration method for retrospective dose estimation.

Objective:To investigate the feasibility of dose estimation based on the dose-response curves established by different types of dicentrics (dic).Methods:Human peripheral blood samples were irradiated by 60Co γ-rays at the doses of 0, 0.5, 1, 2, 3, 4, 5 and 6 Gy with the dose rate of 0.27 Gy/min, and chromosome preparation was carried out. The different types of dics were analyzed. The dose-response curves were fitted with software of Chromosomal Aberration Calculation Software (CABAS). Two samples were used to validate the dose-response curves. Results:The aberration rates of different types of dics increased with the exposure doses ( R2=0.886-0.943, P<0.01). The proportion of typical and single-ended dic components accounted for more than 92% of all types of dic, while the proportion of short-range dic and double-ended dic components was less than 4% at each dose point. The dose-response curves based on different types of dics were established ( R2=0.998, P<0.01). There was no significant difference in the doses estimated by four different dose-response curves ( P>0.05). The relative deviations between actual and predict doses were less than 13.08% by using dose-response curve based on typical dics. Conclusions:Dose-response curves based on different types of dics have the feasibility of dose estimation.

Objective:To explore the effects of ultraviolet B (UVB) on the premature senescence of human immortalized keratinocytes HaCaT cells and the possible underlying molecular mechanism.Methods:HaCaT cells were exposed with UVB of different doses (20, 50, 80 and 100 mJ/cm 2). At 72 h after exposure, cellular morphology was observed by Giemsa staining, cell proliferation was detected by clone formation assay, and the proportion of premature senescence cells was detected by β-galactosidase staining. The number change of lysosomes was detected by Lyso-Tracker Red fluorescence probe at 24, 48 and 72 h after exposure. Cell migration was measured by scratch test at 24 h and 48 h after exposure. The protein expressions of p53 and p16 related to premature senescence were detected by Western blot assay at 72 h after exposure. Results:After UVB exposure, HaCaT cells showed a premature senescence phenotype. At 72 h after exposure, the cell volume increased ( F=115.18, P<0.05), the cell proliferation ability decreased ( F=410.32, P<0.05), the activity of β-galactosidase increased ( F=16.31, P<0.05), and the expressions of P53 and P16 increased. In addition, the number of lysosomes increased at 24, 48, and 72 h after exposure ( F=17.65, 38.36, 13.66, P<0.05), and cell migration capacity was inhibited at 24 and 48 h after exposure ( F=8.21, 11.48, P<0.05). Conclusions:UVB exposure can induce premature senescence of HaCaT cells by increasing the expression of p53 and p16 proteins.