Objective To construct the eukaryotic expression vector of pprI gene from Deinococcus radiodurans R1 and investigate its radioresistant effects in eukaryotic cells.Methods A recombinant vector pEGFP-c1-pprI was constructed by DNA recombinant technique.The empty vector pEGFP-c1 and the pEGFP-c1-pprI were transferred into human lung epithelial cells Beas-2B by LipofectamineTM 2000,respectively.Then the infected cells were screened in order to develop a cell line with stable expression of pprI gene.Cell survival rate was tested by clone-forming assay.Cell cycle distribution and apoptosis were detected by a flow cytometry.The fluorescence intensity of reactive oxygen species (ROS) was observed by a fluorescent microscope.γ-H2AX foci in the irradiated cell was detected by immunofluorescence.Results The eukaryotic expression plasmid of pprI prokaryotic gene was constructed and PprI fusion protein was expressed in human lung epithelial cells successfully,and the cell line (2BG) with a stable pprI gene expression was established.After irradiation,the cell survival fraction of 2BG cells was significantly higher than Beas-2B cells so that the value of D0 、Dq and N of the survival curve were increased.Moreover,the fluorescence intensity of ROS and the number of γ-H2AX foci in 2BG cells were also lower than those of B eas-2B cells(F =16.73,19.47,6.94,P ＜ 0.05).Between these two cell lines,the apoptosis rate and cell cycle G2 arrest also had significant difference (F =139.73,237.92,P ＜ 0.05).Conclusions The pprI gene from Deinococcus radiodurans RI can be stably expressed in the eukaryotic cells and it allows the transferred cells to have a radioresistant function.

Objective To observe the protective effects of different doses of hydrogen-rich water on radiation injury in mice,so as to provide scientific basis for the application of hydrogen-rich water.Methods The ICR mice were randomly divided into control group,irradiation group,amifostine group and hydrogen-rich water of low,medium and high dose groups.The 30 days survival rate,body weight,hematology parameters,serum biochemical parameters,organ weight and coefficient,bone marrow micronucleus rate,bone marrow nucleated cell count were observed after total body irradiation with 9.0 Gy gamma rays.Results After 30 d of irradiation,the hydrogen-rich water showed obvious protective effect on the survival rate and body weight in a dose dependent manner so that the survival was significantly higher than that of irradiation group (t =-2.67,P ＜ 0.05).The biochemical index,such as TP,ALB and CRE in the low dose group,TP,ALB,TBIL and CRE in the medium dose group,and TP,ALB,GLU,TBIL,BUN,GRE and UA in the high dose group also indicated the protective effects of hydrogen-rich water (t =-2.04--4.11,P ＜ 0.05).But the protective effect of hydrogen-rich water was not observed in hematology,organ weight and coefficient,and bone marrow micronucleus induction.Conclusions The hydrogen-rich water has anti-radiation effect,which may depend on the dose of hydrogen.

Objective To investigate the effects of curcumin on UVB-induced elevation of cellular ROS level and cell death and to explore the involvement of transcription factor Nrf2.Methods Mouse embryonic fibroblasts (MEFs) were pretreated with or without curcumin then irradiated with UVB.The cell viability,cellular ROS level and protein levels of Nrf2 and HO1 were determined by MTT assay,DCFH fluorescence and Western blotting,respectively.These measurements were also performed in Nrf2 (-/-) MEFs.Results UVB irradiation elevated cellular ROS level and decreased cell viability of MEFs(t =16.65,15.89,P ＜ 0.05),while the curcumin pretreatment significantly attenuated the deleterious effects of UVB(t =11.88,3.77,P ＜ 0.05).UVB irradiation moderately increased the protein levels of Nrf2 and HO1 and activated JNK and ERK.The curcumin pretreatment led to more remarked elevation of Nrf2 and HO1 proteins,while inhibited UVB-activated JNK and ERK,but it had little effect on p38MAPK.In contrast,Nrf2 (-/-) MEFs showed significantly decrease in Nrf2 and HO1 expressions and were more susceptible to UVB-induced damages.Interestingly,the protective effects of curcumin were also greatly compromised in Nrf2 (-/-) MEFs (t =16.73,-8.23,P ＜ 0.05).Conclusions Curcumin can attenuate UVB-induced oxidative damages in MEFs by activating Nrf2 signaling.

Objective To compare the dosimetric difference of volumetric modulated arc therapy (VMAT) plans for the loco-regionally advanced nasopharyngeal carcinoma (NPC) patients using 6 MV X-ray flattening filter-free (FFF) and flattening filter (FF) modes.Methods Ten previously treated patients with loco-regionally advanced nasopharyngeal carcinoma were retrospectively included and replanned using FFF and FF VMAT,respectively.Meeting all clinical criteria,the dose-volume histograms (DVH),dose distribution of target volume and organs at risk (OARs),target conformity index (CI),total monitor unites (MUs) and treatment time were compared across the plans.Results VMAT plans suing either FFF and FF modes can meet the clinical objectives.The maximum and mean target dose of FFF VMAT plans were significantly higher than that of FF VMAT plans (t =-0.31,-O.35,P ＜ O.05).Yet the planning target volume (PTV) CI of FF mode was slightly better than of FFF mode (t =5.42,P ＜0.05).The maximum doses of lenses in FFF VMAT plans were lower than that of FF VMAT plans (t =25.87,17.45,P ＜ 0.05),and other OARs displayed no significant difference.The mean total MUs of FFF and FF VMAT plans were (699 ± 16) and (628 ± 12) MUs respectively.The mean treatment time of two modes were consistent (about 2 min).Conclusions The plan qualities of FFF and FF VMAT plans were comparable and both clinically acceptable.The OARs at the edge of radiation field,such as lens,could be spared better using FFF VMAT mode.The total MUs of FFF VMAT plans were higher than FF VMAT plans,yet were delivered within the same time.

Objective To analyze radiation induced alterations of vitronectin and collagen expressions in fibroblasts at different times post-irradiation,so as to evaluate the potential to apply vitronectin as a biomarker of radiation-induced lung fibrosis.Methods The human fibroblast cells WI-38 and IMR-90 were irradiated with 137Cs γ-rays at doses of 0 (control),4,6,8,10 and 12 Gy,respectively.The cells and its supernatant were collected at 6,12,24,36,48 and 60 h post-irradiation.The expressions of vitronectin and collagen Ⅰ and Ⅲ were analyzed by Western blot,PCR and ELISA.Results After irradiation,the expressions of vitronectin and collagen Ⅰ and Ⅲ were positively correlated (r=0.40-0.79,P＜0.05) and were all significantly higher than that in control group (t =3.04-25.45,P ＜0.05) and reached the highest expression levels at 48 h after 8-10 Gy of irradiation (t =2.92-18.86,P ＜ 0.05).Analyses of Real-time PCR and ELISA assay showed that expressions of vitronectin mRNA and its protein level in the cell lysis were significantly increased by radiation (F =27.09-42.62,P ＜ 0.05).Conclusions The expressions of vitronectin in cellular supernatant and its mRNA may be a potential biomarker of radiation-induced fibrosis,and 48 h after 8 Gy irradiation may be an optimum condition of measurement.

Objective To investigate the effects of EMP exposure to male BABL/c mice on the reproduction and its sex ratio.Methods Thirty-three male BALB/c mice were randomly divided into sham-exposed group,10 000 pulses/d exposed group,and 100 000 pulses/d exposed group with 50 Hz static magnetic field of 35 kV/m for 2 weeks consecutively,then the male mice were mated with unexposed females (1 male vs.2 female).Mated males were sacrificed to examine the exposure effects on sperm number and testis index after 7 days of mating.The sex ratio of embryos collected from unexposed mated females was investigated by PCR.Results The sex ratio of offspring was 0.298 (14/47) in the 10 000 pulses/d exposed group,significantly lower than 0.871 (27/31) in the sham-exposed group.No statistical changes were observed in the sex ratio of offspring,sperm number,the weights of testis and testis index after 100 000 pulses/d exposure.Conclusions The exposure of male mice to 35 kV/m EMP at 10 000 pulses/d for 2 weeks consecutively may change the sex ratio of mice's offspring.

Objective To investigate the variations of the spatial position and overlap ratio of the internal target volume (ITV) and planning target volume (PTV) of primary thoracic esophagus carcinoma using repeated four-dimensional computed tomography (4D-CT) scanning during conventional fractionated radiotherapy.Methods Thirty patients with thoracic esophageal carcinoma were included whose 4D-CT scans were conducted before radiotherapy and between every ten fractions.The gross tumor volumes (GTVs) were delineated by the same radiation oncologist on each 4D-CT image phase,and the ITV and PTV were constructed afterwards.Results No significant difference of the isocenters was observed for the ITV and PTV during the treatment course,yet both the volumes of the ITV and PTV decreased.The median DI (the degree of inclusion) of the target acquired subsequently in the original target were 0.85,0.77 (Z=-3.10,P ＜0.05) for ITV and 0.86、0.82(Z =-2.49,P ＜0.05)for PTV respectively during entire treatment.The variation of volume ratio correlated strongly with the variation of DI (the DI of the target acquired subsequent in the original target) (rITV =0.71,rPTV =0.77,P ＜0.05).The variation of volume ratio and the variation of the matching index (MI) were positively correlated (rITV =0.47,rPTV =0.59,P ＜ 0.05).The 3D vectors of ITV and PTV motions were negatively correlated with the corresponding MI (rITV =--0.52,rPTV =-0.36,P ＜ 0.05).If the initial PTV was used for treatment planning,8.80％ and 6.37％ of the target volume would be missed at the tenth and twentieth fraction (Z =-0.55,P ＞ 0.05),respectively.In the meanwhile,11.45％ and 18.49％ of the normal tissues would be wrongly irradiated at the corresponding time points (Z =-2.49,P ＜ 0.05).Conclusions The variations of the spatial position of all targets were all less than 0.6 cm.The DI and the MI of the target decrease by various degrees during the treatment course,which lead to target mispositioning and normal tissue irradiation at different levels.

Objective To select an efficient ion exchange resin to purify the 60Co contaminated well-water for storing radioactive source and to ensure the radioactivity of 60Co in treated well-water below 10 Bq/L.Methods The radioactivity of 60Co in the water samples was measured by using the potassium cobaltinitrite coprecipitation-β counting method.The treatment efficiencies of two different ion exchange resins for the simulated 60Co-bearing waste water were compared to select a better one to dispose of the 60Co contaminated well-water.Results The treatment efficiency of MBD-15-SC mixed ion exchange resin was about 5.8 times higher than ZGCNR50 strong-acid cation exchange resin.The radioactivity of 60Co in the contaminated well-water could be reduced from 4.16 × 105 Bq/L to 1.16 Bq/L by two-stage sorption of MBD-15-SC mixed ion exchange resin.Conclusions Using several times of two-stage MBD-15-SC mixed ion exchange resin could effectively purify the 60Co contaminated well-water.The quality of the treated well-water could meet the sewage discharge standards.

Objective To determine the activity concentration of radionuclides for 137Cs and 40K in edible wild mushrooms,and to evaluate the extent of radioactive contamination and ingestion doses to adults from consumption of these wild mushrooms.Methods A total of 33 samples for 18 edible wild mushroom species were collected from natural forest Mangshi,Yunnan province.The activity concentrations of 137Cs and 40K were analyzed by using high-purity germanium (HPGe) gamma spectrometry.Results Except.for one sample that was below the MDA,137Cs artificial radionuclides were detected in other 32 samples,with activity concentration of 137Cs in the range of 0.45-339.58 Bq/kg (dry weight) and an average of 25.47 Bq/kg (dry weight).In regards to 40K in edible mushrooms,all species presented the activity concentrations for this radionuclide and the levels varied from 453.4 to 1 882.6 Bq/kg (dry weight),with an average of 815.1 Bq/kg (dry weight).After species of mushroom with only one sample were eliminated,there was significant difference for 137Cs(F =21.13,P ＜ 0.05) among 6 species of mushroom named Gomphus floccosus (Schw.) Sing.,Boletus edulis bull,Boletus edulis bull,Tylopllus bolloul (Peck) Sing.,Lentinus edodes (Berk.) Sing.and Boletus brunneissimus W.F.Chin,but without significant difference for 40K.Conclusions These 6 different mushroom species have different capacity to retain radionuclides of 137Cs in soil.These wild mushrooms,such as Gomphus floccosus (Schw.) Sing.and Lentinus edodes (Berk.) Sing.have large affinity ability for radionuclides137Cs.The effective dose to adults attributable to consuming these kinds of mushrooms is small and below the level that could cause harm.

Objective To compare the dosimetric differences of target and organs at risk (OAR) induced by the tangential and non-coplanar multi-fields used in the dynamic intensity modulated radiotherapy (IMRT) plans for breast cancer patients after breast-conserving surgery.Methods Forty patients with early-stage left breast cancer after breast-conserving surgery were included.Based on the CT anatomy of the same patient,dynamic IMRT treatment plans using two tangential fields,3,4 and 5 non-coplanar fields were designed respectively utilizing the same optimization objects.The plans were compared by means of target dose distribution,the doses and irradiated volumes of heat,left lung,right breast,and total monitor units (MUs).Results The conformal index (CI) and homogeneity index (HI) of planning target volume (PTV) in the plans using 4 and 5 fields were better than that using 2 fields (P ＜ 0.05).Maximum doses (Dmax) in PTV were significantly lower in the plans of 4 and 5 fields than of 2 fields (P ＜0.05).Yet the plans of 4 and 5 fields generated significant higher minimum doses (Dmin) in PTV than that of 2 fields (P ＜ 0.05).No significant difference was observed between plans of 2 or 3 fields.Across the four plans,the differences of right breast V5 (relative volume acquired at least 5 Gy of dose),heart V30,heart mean dose (D),left lung V20,V5 and D were not significant.Yet the disparities of total MUs were statistically significant (F =25.63,P ＜ 0.05).The least MUs were used by the 2 fields and the most MUs were observed in the 5-field plans.Conclusions Comparing with IMRT plans of 2 fields,using 4 or 5 non-coplanar fields can improve the target dose distribution without increasing OAR doses.As a tradeoff,more MUs are needed for multi-fields plans.