title: [Effect of radiation dose and dose rate on pulmonary fibrosis in mice].
abstract: OBJECTIVE
  To study the effect of radiation dose and dose rate on radiation-induced pulmonary fibrosis in mice.
  
  
  METHODS
  Twenty-four C57BL/6 mice were randomly divided into a control group (n=6) and an irradiation group(n=18). The irradiation group was further assigned to 3 subgroups according to the whole lung radiation with 15 Gy at 400 cGy/min, 20 Gy at 400 cGy/min and 20 Gy at 100 cGy/min, while the control group received sham-irradiation. All mice were scanned with computed tomograph (CT) 20 weeks post-irradiation, and then they were sacrificed and lung tissues were collected. H&E staining, sirius red staining, lung fibrosis scored and hydroxyproline content analysis were used to assess lung fibrosis and collagen deposition. Real time PCR was used to measure the mRNA expression of type Ⅰ collagen. Immunohistochemical staining was used to detect the activatin and distribution of a-SMA(+) -myofibroblasts.
  
  
  RESULTS
  Compared to the control group, mice from irradiation groups exhibited significant pulmonary consolidation and collagen deposition.At the same dose rate, the higher irradiated dose used, the more severe pulmonary fibrosis was.On the other hand, with the same dose, the dose rate had less effect on pulmonary fibrosis.
  
  
  CONCLUSIONS
  The effect of radiation dose on the degree of pulmonary fibrosis in mice is more than effect of the dose rate.
authors.affiliation: Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer.
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Chen
authors.affiliation: Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, College of Life Sciences, Nankai University, Tianjin 300071, China.
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: Y S
authors.initials: YS
authors.lastname: Fang
authors.forename: A X
authors.initials: AX
authors.lastname: Zhang
authors.forename: Z F
authors.initials: ZF
authors.lastname: Yang
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Yuan
authors.forename: W
authors.initials: W
authors.lastname: Ning
mesh_terms: D000818:Animals; D024042:Collagen Type I / Q000378:metabolism; D006909:Hydroxyproline / Q000032:analysis; D008168:Lung / Q000473:pathology* / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D011658:Pulmonary Fibrosis / Q000473:pathology*; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000473:pathology*; D011897:Random Allocation
chemical_list: D024042:Collagen Type I; D006909:Hydroxyproline