Objective To study the effect of γ-rays irradiation on the differentiation potential of the human peripheral blood monocytes (PBMCs) into osteoclast-like cells (OCLs) in vitro.Methods PBMCs were isolated by density gradient centrifugation,treated by receptor activator of nuclear factor-κ B ligand (RANKL) and macrophage-colony stimulating factor (M-CSF) and exposed to 137Cs γ-rays with different radiation doses (0,0.75,2 Gy).After seven days of incubation,the cells were stained for tartrate resistant acid phosphatase (TRAP) and bone slices were stained by toluidine blue on the tenth day.Meanwhile,the characteristic osteoclast markers including Cathepsin K and integrin β3 were analyzed by real-time PCR.Tartrate resistant acid phosphatase 5b (TRAcP-5b) in the culture supernatant wasdetermined by ELISA.Results PBMCs were differentiated into OCLs by the treatments of RANKL and MCSF.The number of TRAP positive multinucleated OCLs was significantly higher in the dose of 0.75 Gy group than in control (0 Gy) group (t =3.451,P ＜ 0.05).Compared with the control group,the expression levels of Cathepsin K and integrin β3 and the concentration of TRAcP-5b were significantly elevated (t =2.343,2.728,3.631,P ＜ 0.05).However,in the 2 Gy group,there was a decrease in the number of osteoclasts,mRNA expression level of osteoclast characteristic markers and TRAcP-Sb,but no statistically significant differences compared with the control group.Conclusions Ionizing radiation may influence the osteoclastogenesis during the PBMCs differentiation to OCLs.At low dosage,ionizing radiation promotes osteoclastogenesis and enhances the resorptive activity of osteoclasts,but a decline of differentiation potential was observed at high dosage of radiation.

Objective To explore the feasibility of using glycophorin A somatic mutation in peripheral erythrocytes,in order to evaluate the cancer risk of occupational medical exposure to ionizing radiation.Methods Totally 336 medical radiation workers were recruited as three groups (general radiation group,computer tomography group,intervention and radiation treatment group) and 112 healthy adults were selected as control by using stratified random cluster sampling method,where 176 medicalradiation workers and 58 health controls had a MN-heterozygous type.The erythrocytes were fixed and bound with fluorescent-labeled monoclonal antibody,and the glycophorin A somatic mutation frequency was assayed by a modified BR6-1W1 method using a FACScan flow cytometer.The individual susceptibility to radiation was investigated using micronuclei test and 3-Aminobenzamide index test.Results The GPA somatic mutation frequency of medical-radiation workers was significantly higher than that of healthy control ( t =2.29 - 11.48,P ＜ 0.05 ).In particular,the NO GPA aberration frequency of interventional radiology workers was much higher than that of the general medical diagnostic workers (t =2.01,P ＜ 0.05).In addition,the NO GPA variant frequency changed significantly with the years of radiation service,cumulative doses,and 3AB index.However,the NN GPA variant frequency was only associated with the years of radiation service,and no significant correlations were found between NN GPA variant frequency and cumulative dose of radiation exposure or 3AB index. Conclusions GPA mutation frequency,especially NO GPA mutation frequency could be used as a sensitive biomarker to predict the DNA damage and individual susceptibility for the population exposed to professional low-dose ionizing radiation.

Objective To observe the expression of serine/threonine kinase 31 (STK31) in osteosarcoma and its effect on the malignant biological behavior of osteosarcoma.Methods Fifteen cases of osteosarcoma specimens and adjacent normal tissue were collected.The expression of STK31 in tumor tissues and normal tissue were detected by immunohistochemistry,real-time quantitative PCR and Western blot.The STK31 knockout plasmids PGenesil-STK31-shRNA or control plasmid pGenesil-1 were transfected into osteosarcoma cell line MG63 cells.The effect of STK31 on the proliferation of MG63 cells was detected by CCK8 cell activity assay.Tanswell experiment was used to observed the effect of STK31 on the migration ability of osteosarcoma cells.Results Immunohistochemical showed that STK31 expressed in the tumor tissue,and it was significantly higher than the adjacent normal tissues;Real time quantitative PCR[(3.65±0.83)vs.(1.05±0.14),P＜0.05] and Western blot also revealed that STK31 expression in tumor tissue were significantly higher than adjacent normal tissues(P＜0.05);CCK8 experiments showed that knockdown STK31 inhibited proliferation of MG63 cell when compared with the control group after 36 h[(1.71±0.17)vs.(1.39±0.11),P＜0.05],72 h[(2.15±0.21)vs.(1.54±0.14),P＜0.05];Tansewell experiments showed that transfection of pGenesil-STK31-shRNA could suppress MG63 cell's migration[(13±4)vs.(55±8),P＜0.05].Conclusion STK31 is overexpression in osteosarcoma with increased biological activity of osteosarcoma cells.

Objective To investigate whether mild hypothermia can promote neurogenesis in the dentate gyrus of hippocampus and cognitive function recovery after traumatic brain injury ( TBI) through inhibiting apoptosis of hippocampal neurons. Methods A total of 66 healthy adult Sprague-Dawley rats were randomly divided into sham group, TBI group and TBI+hypothermia group, with 22 rats in each group. The rat TBI model was established using the fluid percussion device. The rats in TBI +hypothermia group received 4-hour hypothermia therapy immediately after injury, with the target temperature of 33. 5℃. Bromodeoxyuridine (BrdU) was injected into the rats' abdominal cavity to label the mitotic cells. The test of Morris water maze was used to evaluate the rats' spatial learning and memory capabilities. Immunofluorescence staining was used to observe the expression levels of BrdU, doublecortin (DCX), neuron specific nuclear protein (NeuN), cysteinyl aspartate specific proteinase 3 (caspase-3) and cleaved caspase-3 expressions in dentate gyrus of hippocampus at 7 days and 28 days after injury. Expressions apoptosis-related proteins including the factor associated suicide ( FAS )/factor associated suicide ligand (FASL), B-cell lymphoma-2 (Bcl-2), caspase-3 and cleaved caspase-3 expressions were detected by Western blot assay. Results The water maze tests at 28 days after injury showed that compared with TBI group, the escape latency in TBI+hypothermia group was significantly shorter [(24. 2 ± 5. 9)s:(18 ± 4. 1)s], and both the time in the target quadrant and the number of platform crossing were increasedsignificantly[(24.9±6.5)s:(31.7±5.2)s; (1.9±0.8) times:(3.5±1.2)times](P<0. 05). Compared with the sham group, in TBI group and TBI+hypothermia group, the BrdU+ new-born cells in the dentate gyrus of hippocampus were significantly increased at 7 days after injury [(9. 4 ± 4. 1):(33. 4 ± 3. 8);(9. 4 ± 4. 1):(45. 8 ± 5. 6)], the BrdU+ /DCX+ new-born neurons were increased at 7 days after injury [(2. 0 ± 0. 6):(9. 6 ± 1. 6);(2. 0 ± 0. 6):(19. 2 ± 3. 7)], and the BrdU+ /NeuN+mature neurons were increased at 28 days after injury [(2. 6 ± 1. 0) :(17. 2 ± 3. 9); (2. 6 ± 1. 0) :(33. 6 ± 9. 1)] (P<0. 01). TBI group showed more obvious increase than the TBI+hypothermia group (P<0. 01). Moreover, compared with 7 days after injury, the number of BrdU+ cells at 28 days after injury was further increased in TBI +hypothermia group but decreased in TBI group [(45. 8 ± 5. 6) :(58. 8 ± 9. 2);(33. 4 ± 3. 8):(22. 0 ± 3. 5)](P<0. 05 or <0. 01). Compared with the sham group, the caspase-3 +NeuN+ and caspase-3 +NeuN+ apoptotic neurons were significantly increased at 7 days after injury in TBI group [(2. 0 ± 0. 9):(11. 6 ± 2. 6); (2. 6 ± 1. 0):(10. 2 ± 2. 9)] (P<0. 05). Compared with the TBI group, the cleaved caspase-3 +NeuN+ apoptotic neurons were decreased in TBI+hypothermia group [(6. 6 ± 2. 0):(11. 6 ± 2. 6)](P<0. 05). Furthermore, compared with the TBI group, mild hypothermia might down-regulate the expression of FAS, FASL, cleaved caspase-3 and caspase-3 and up-regulate the expression of Bcl-2 in the hippocampus [(1. 54 ± 0. 15) :(1. 14 ± 0. 12);(1. 06 ± 0. 04):(0. 80 ± 0. 09); (0. 84 ± 0. 03):(0. 62 ± 0. 08); (0. 93 ± 0. 06):(0. 86 ± 0. 09);(0. 71 ± 0. 01):(1. 58 ± 0. 18)](P<0. 05). Conclusions Mild hypothermia might inhibit apoptosis of hippocampal neurons through cleaved caspase-3, FAS/FASL and Bcl-2 pathways, thus improving the neurogenesis and maturation of neurons in the dentate gyrus of hippocampus and facilitating cognitive function recovery in rats. It indicates that the function of hypothermia in anti-apoptosis and neurogenesis and maturity of hippocampal neurons may have a potential role in predicting the prognosis of TBI patients.