OBJECTIVE: To explore the effect of genomic stability of PTEN-deficient mice embryonic fibroblasts after transfection with RAD51，an important homologous recombination repair gene. METHODS： Immunofluorescence assay was used to observe the number of spontaneous γ-H2AX foci. Neutral single cell gel electrophoresis was applied to detect spontaneous and radiation-induced DNA double-strand breaks in both PTEN-deficient and PTEN wild-type cells. RESULTS：PTEN deletion led to an increase of spontaneous γ-H2AX foci and the length of tail moment， indicating DNA double-strand breaks. Transfection with RAD51 increased cell survival and decreased radiation-induced DNA double-strand breaks of PTEN-deficient cells. CONCLUSION：Homologous recombination gene RAD51 could increase genomic stability of PTEN-deficient cells.

OBJECTIVE: To study the variation of the levels of antioxidant proteins，active oxygen radicals and DNA double-strand breaks in the malignantly transformed human bronchial epithelial cell line BEP2D induced by α-particles. METHODS：Western blot was applied for the detection of the protein expressions of catalase (CAT)，glutathione peroxidase (GPXs)，Cu/Zn superoxide dismutase (Cu/Zn-SOD) and Mn superoxide dismutase (Mn-SOD) in BEP2D，RH22，and BERP35T-1 cells. SOD assay kit was employed to measure total SOD (T-SOD)，Cu/Zn-SOD and Mn-SOD enzyme activities in BEP2D，RH22 and BERP35T-1 cells. Using 2’，7’-dichlorofluorescein diacetate (DCHF-DA) and dihydroethidium (DHE)，the generation of H2O2 and superoxide anion (O2－.) in BEP2D，RH22 and BERP35T-1 cells was monitored by flow cytometry. Neutral single cell gel electrophoresis (SCGE) was used to compare the differences of the levels of DNA double-strand breaks in BEP2D，RH22 and BERP35T-1 cells. RESULTS：Compared to BEP2D cells，CAT and GPX1 were down-regulated，but GPX3，Cu/Zn-SOD and Mn-SOD were up-regulated at protein level in RH22 and BERP35T-1 cells (P＜0.05 or P＜0.01). Corresponding to their protein expression levels，RH22 and BERP35T-1 showed increased T-SOD，Cu/Zn-SOD and Mn-SOD enzyme activities (P＜0.05 or P＜0.01). Decreased basal level of O2－. and increased basal levels of H2O2 and DNA double-strand breaks were observed in RH22 and BERP35T-1 cells compared to BEP2D cells (P＜0.05). CONCLUSION： Oxidant/antioxidant imbalance promoting oxidative DNA damage which may result in genomic instability could contribute to the acceleration of cellular malignant transforming process in human bronchial epithelial cell line BEP2D induced by α-particles.

OBJECTIVE: To provide gene-level evidence for hepatic early damage of staff exposed to irradiation. METHODS：The study analyzed the differential gene experession profile of normal human hepatocytes and human hepatocytes irradiated at 2 different doses (0.5 and 1.0 Gy γ- rays) using whole genome chip after 4 and 24 h. RESULTS：There were 218 differentially expressed genes irradiated with 2 doses after 4 h，and there were 1 475 differentially expressed genes irradiated with 2 doses after 24 h. There were 235 differentially expressed genes irradiated with 0.5 Gy in 2 time-points. There were 170 differentially expressed genes irradiated with 1.0 Gy in 2 time points. There were 129 differentially expressed genes irradiated with 0.5 Gy and 1.0 Gy at 4 h and 24 h. Some interesting pathways such as insulin synthesis and secretion were found. The quantities of IGF2BP3 and EGR1 mRNA analyzed with real-time PCR were consisitent with gene chip. CONCLUSION：There were 129 differentially expressed genes identified. Irradiation caused early damage to human hepatocytes at many targets，many levels and through many pathways .

OBJECTIVE: To study the expression changes of Arp2，Arp3 and cofilin genes of lymphocytic microfilament in thymus gland induced by different doses of γ-rays in BALB/c mice. METHODS：40 BALB/c mice were divided into five groups. Four groups were separately exposed toγ-rays with 0.02，0.1，1 and 6 Gy in whole body. One group was control. Every group had 8 mice. After 3 hours induced byγ-rays，the mice were given cervical dislocation，chests and thymuses were collected. Thymus cells were flowed out by PBS immited. mRNA and proteins of Arp2，Arp3 and cofilin genes were extracted from thymus cells. Their mRNA expressions proteins were detected by fluorescent quantitation PCR. The Arp2，Arp3 and cofilin proteins were measured by western-blot. RESULTS： Compared with control， mRNA expressions of Arp2 gene induced by γ-rays with different doses were not statistically significant，but Arp2 protein expressions induced byγ-rays with 1Gy were upward (H=2.33， P<0.05)；mRNA expressions of Arp3 gene induced by γ-rays with 1 Gy were downward (t =-12.77，P<0.01)，mRNA expression of Arp3 gene induced by 6 Gyγ-rays were upward (t = 3.39，P<0.05)，differences of Arp3 protein expressions induced by γ-rays with different doses were not statistically significant；mRNA expressions of cofilin gene of groups induced seperately byγ-rays with 0.02，0.1 and 1 Gy were upward (t =6.38-9.41，P<0.01)，while differences of cofilin protein expressions induced by γ-rays with different doses were not statistically significant. CONCLUSION：Afterγ-rays induced with different doses，the expressions changes of Arp2，Arp3 and cofilin genes took place in thymus gland of BALB/c mice. Characteristics of the their changes were associated with doses of γ-rays. These results provided experimental evidences for the mechanism of changes of lymphocyteic microfilament meshwork induced by γ-rays.

OBJECTIVE: To identify the specific tumor markers of lung cancer induced by irradiation for diagnose and therapy by proteomics．METHODS：Samples of BEP2D cells irradiated with 0，1.5 and 3.0 Gy γ-rays for 24 h were cultivated and collected，and total protein was separated with the two-dimensional gel electrophoresis. The peptide mass fingerprints were obtained using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS)for differentially expressed proteins. RESULTS：10 peptide mass fingerprinting were revealed in the mass spectra identification，8 of them approved in the database (2 null)，and 1 duplicated．There were 7 points identified in the initial tests by Mascot software in the NCBInr databates，such as cyclophilin A，myosin light chain 2，cytokeratin 9，α-enolase，triosephosphate isomerase 1，makorin ring finger protein 1，c-myc promoter-binding protein 1. CONCLUSION：The 7 proteins probably were the special proteins related to lung cancer induced by irradiation，which might be used for further study of the functions of the proteins．

OBJECTIVE: To investigate effects of urinary metabolites from single exposure to γ radiation and to screen urinary metabolites related close to γ radiation damage in rats. METHODS：15 male adult SD rats were exposed to 60Coγ-rays whole body once at 6.0 Gy，0.7 Gy/min. Urine was collected from rats one day before irradiation and 1 d，2 d，3 d，4 d，8 d，18 d，30 d and 45 d after irradiation. Urine 1H NMR spectra were acquired，principal component analysis (PCA) and partial least-squares-discriminant analysis (PLS-DA) methods are utilized to analyze 1H NMR spectra data. Then we looked for the metabolites that contributed more in the difference between urine 1H NMR spectra before exposure and every time after exposure( abbreviateed as common difference metabolites) and analyzed relation between the change of their relative contents and post-irradiation time. RESULTS：60Coγ irradiation could cause visible change of urine 1H NMR spectra. Common difference metabolites were taurine，trimethylamine-N-oxide，proline，creatinine，citrate，succinate，acetate and lactate that coutributed more in change of 1H NMR spectra of urine collected at different times after exposure. For 1-45 d after exposure，the relative contents of proline and taurine were markedly higher than before irradiation，and citrate and succinate were lower. However，the relative contents of trimethylamine-N-oxide，acetate and lactate first increased 1 d after irradiation and then decreased for 2-45 d after irradiation. CONCLUSION：The disorder of metabolism in rats induced by high-dose γ radiation did not completely recover for 45 days after irradiation，that showed persistent changes of the relative contents of urine taurine， proline，creatinine，citrate，succinate，acetate and lactate in exposed rats. Taurine and proline could become potential combined metabolic markers of acute high-dose radiation injury.

OBJECTIVE: To investigate the changes of COX II gene expression in lymphoblastoid cells induced by ionizing radiation，in order to provide scientific evidence for gene expression as a biomarker in radiobiodosimetry. METHODS：Lymphoblastoid cells were irradiated by 60Co γ-rays at doses of 0-15 Gy，and then cultured for different periods of 0-72 h. The levels of COX II gene expression were measured by real-time PCR and Western blot. RESULTS：Real-time PCR results showed there were no significant changes in COX II gene expression at the transcriptional level after irradiation by 0-15 Gy 60Co γ-rays (P>0.05). While，at the translation level，COX II gene expression levels were significantly increased 24-72 h after being irradiated by 60Co γ-rays (P﹤0.05). In particular at two post-irradiation time-points，48 h and 72 h，COX II gene expression level correlated with radiation dose. The radiation-induced changes of COX II gene expression between the mRNA and protein levels in human lymphoblastoid cells were not identical. CONCLUSION：At the translation level，radiation could significantly increase COX II gene expression 24-72 h after irradiation in human lymphocytes，and showed good dose- response relationships at 48 h and 72 h. COX II has the potential of becoming a sensitive biomarker and biodosimeter for radiation damage.

OBJECTIVE: To explore the feasibility of single cell gel electrophoresis (SCGE) in estimation of radiation biological dose. METHODS：Normal peripheral blood samples from two healthy males were exposed to different doses 60Co γ-rays，ranged from 0 to 16 Gy. Immediately and 1 h later，tail moment (TM) of the peripheral blood cells were analyzed with casp software in order to establish dose-effect relationship. RESULTS：The TMs immediately after radiation of peripheral blood cells increased with the irradiation doses，and its relationship can be fitted as：Y＝0.836 7＋0.530 9D＋0.079 9 D2 (R2＝0. 9962，P＜0.05) from 0 to 16 Gy，and Y＝0.400 3＋1.129 1D (R2＝0.9963，P＜0.05) from 0 to 8 Gy. The TMs of peripheral blood cells 1 h after radiation increased with the irradiation doses，and its relationship can be fitted as：Y ＝0.461 6 ＋ 0.656 0D＋0.062 1 D2 (R2＝0.998 4，P＜0.05) from 0 to 16 Gy，and Y＝0.107 1＋1.128 3D (R2＝0.999 5， P＜0.05) from 0 to 8 Gy. CONCLUSION：The TM of peripheral blood cells analyzed with SCGE is a promising radiation biological dosimeter at high doses.

OBJECTIVE: To explore the feasibility of rapidly estimating biological dose under shortened incubation time and establish dose-effect curve of premature chromosome condensation rings (PCC-R) in human lymphocytes induced by γ-rays. METHODS： Human peripheral blood was irradiated in vitro by 60Co γ- rays at 0，1，3，6，10，15 and 20 Gy. PCC-R was counted after 44 h and 48 h incubation with Okadaic acid added 1 h before harvest. Both 44 h and 48 h dose-effect curves were established and compared. RESULTS：Cells obtained from 44 h incubation was slightly decreased，and PCC rings rate was slightly lowered compared with 48 h incubation ( P>0.05). PCC rings rate increased with dose and demonstrated a perfect linear relationship (0-15 Gy) ，with a linear equation Y= - 0.015 2+ 0.062 5D (R2=0.983 9). CONCLUSION：After shortening the incubation time to 44 h，PCC rings could still be used in dose estimation of high dose radiation incidents within 15 Gy.

OBJECTIVE: To establish dose-response relationship between prematurely condensed chromosome (PCC) rings of human peripheral lymphocytes and neutron radiation. METHODS：Heparinized peripheral blood was taken from two healthy adult females and irradiated by 0，1.0，2.5，5.0，7.5 and 10.0 Gy of neutron (dose rate 0.2 Gy/min). Blood was kept in incubator (37 ℃) for 3 h for cell repair. Then blood was cultured with RPMI 1640 for 48 hrs. 1 hr before the end of culture，Okadaic acid，at final concentration of 500 nmol/L， was added into culture medium to induce PCC rings. Yield of PCC rings at each dose point after staining with Giemsa was counted and the relationship between PCC rings of human peripheral lymphocytes induced by neutron radiation was examined. RESULTS：In 500 nmol/L Okadaic-acid-induced prematurely condensed chromosomes of human peripheral lymphocytes， the yield of PCC rings increased with the dose of radiation and showing a linear correlation (y=0.097 6x+0.000 3， R2=0.980 5). CONCLUSION： A good dose-response relationship was found between the yield of PCC rings and radiation dose from 0 to 10 Gy. The yield of PCC rings could be used as a biodosimeter in neutron irradiation，especially for high dose.

OBJECTIVE: To identify the changes of the percentage of reticulocytes and Th-to-Ts ratios (rTh/Ts) from peripheral blood in mice following total body irradiation(TBI) in order to confirm the feasibility of bio-dosimeter about radiation damage. METHODS：Seven to eight weeks-old C57BL/6 mice were treated with TBI at doses ranging from 1 Gy to 7Gy. Peripheral blood was collected for flow cytometric analysis，percentage of reticulocytes and rTh/Ts were acquired. RESULTS：Reduced reticulocyte percentages were observed with the doses in the range of 0～7 Gy post-irradiation，minimal reticulocyte percentages were observed at 3 d，and the recovery of reticulocytes was increasingly delayed with higher radiation doses. RTh/Ts increased with doses in the range of 0～7 Gy within 72 h post-irradiation. Percentage of reticulocytes declined with the doses in the range of 1～3 Gy at 24，48 and 72 h post-irradiation. rTh/Ts increased with doses in the range of 1～7 Gy at 6，24 and 72 h after TBI. The dose-response relationships of both reticulocyte percentage and rTh/Ts fitted to the lineal model. CONCLUSION：Percentage of reticulocytes and rTh/Ts ratios analyzed with flow cytometry，could be an early，rapid and high-throughput radiation bio-dosimeter.

OBJECTIVE: To study the dose and time effects of X-rays on the expressions of Bmi-1 gene and protein in human lung adenocarcinoma cell line A549. METHODS：A549 cell line was exposed to different doses of X-rays (2，4，6 Gy )and the relative level of Bmi-1 mRNA and protein was detected by using quantitative real-time PCR and Western blot at 6，12，24，48，72 h after irradiation. The untreated A549 cells were used as control. RESULTS： Bmi-1 mRNA in A549 cells was highly regulated after irradiated with 2，4，6 Gy and the peaked at 6 h，12 h and 24 h respectively. The expression of Bmi-1 mRNA，except for 2 Gy group，after 48 h showed statistical difference compared with the untreated group(P<0.05). After radiation， the expression of Bmi-1 protein was significant at most time points (P<0.05)，increased during 48 h，but was decreased after 48 h，and approached level of the untreated at 72 h. CONCLUSION：Under our experimental conditions，2-6 doses of X-rays radiation could increase the expressions of Bmi-1 mRNA and protein in A549 cells .

OBJECTIVE: To observe the damage of target organs of rats exposed to radon，especially the pathological changes of lung tissue，as well as the expressions of RAGE and S100A6 proteins，and to provide information for exploring the mechanisms of potential carcinogenic effects of radon on the lungs. METHODS：16 male rats were randomly divided into 4 groups ，i. e. control group，low (64WLM)、middle (121 WLM) and high (236 WLM) dose groups，with 4 rats in each group. The Wistar rats were exposed to radon in a multifunction ecological radon room at a constant level of 10 0 000 Bq/m3，12 h each day. Pulmonary pathological changes were examined，then the organ coefficients and the rate of bone marrow micronucleus were calculated，8-OHdG in peripheral blood lymphocytes was assessed by ELISA and T-AOC in serum was determined by ultraviolet spectrophotometer. The RAGE and S100A6 proteins were measured by western blot. RESULTS：In the high dose group，inflammatory cell infiltration and thickening of alveolus septa were observed. The liver coefficient increased and the testis coefficient decreased. Rate of bone marrow micronucleus significantly increased. Level of 8-OHdG in peripheral blood lymphocytes was elevated and that of T-AOC declined. The expressions of RAGE and S100A6 in lung tissue were up-regulated in a dose-response relationship. CONCLUSION：Chronic exposure to radon may induce multi-organ damage，especially pathological alterations of lung tissue at high exposure dose.

OBJECTIVE: To assess the radiotherapy damage using hprt gene mutation in cervical cancer patients. METHOD：Blood samples were collected from 15 cervical cancer patients exposed to radiation at the accumulated dose of 0-60 Gy. hprt gene mutation was studied by multinucleated cell assay. RESULT：Mutation frequency of hprt gene increased after radiation. The frequency increased significantly at dose 30，40 and 50 Gy compared to 0 Gy (P＜0.05 ). At the accumulated dose of 60 Gy，the mutation frequency was also higher than 0 Gy，but not statistically significant. The increase of hprt gene mutation frequency was linear from 0-40 Gy. There was a good dose-response effect between mutation frequency of hprt gene and accumulated dose ( r＝0.900，P＜0.05 ). Analysis showed a linear dose-response with an equation of y＝0.459＋0.014 x ( r＝0.900， P＜0.05). CONCLUSION：Mutation frequency of hprt gene increased after radiation from 0-40 Gy. There was a good dose-response relationship between mutation frequency and accumulated dose. Mutation frequency of hprt gene could be a valuable biodosimeter.