Transcript الشريحة 1
Laboratory of Radiation Biology Chromosomal analysis for calibration curve creation for potential retrospective dose estimation Egyptian Candidates Nadia Abdrabo Samak Fayrouz Sayed Ahmed Supervised by • Dr. Polina Kutsalo • Dr. Anna Rzjanina Contents • Aim of our work • Introduction • Methodology • Results • Conclusion • References Aim of our work Establishing calibration curve for unstable chromosomal aberrations induced by the proton beam used in cancer therapy at Laboratory of Nuclear Problems at JINR. Introduction What are chromosomes? • Chromosomes are the things that make organisms what they are. • They carry all of the genetic information used to help cell growth and reproduction. Chromosome structure DNA and Histone proteins are packaged into structures called chromosomes. Shapes of different stages of chromosomes under microscope (a) S-phase (b) Early G2-phase (c) Late G2-phase (d) Metaphase (e) Anaphase (f) G1-phase Courtesy of R.Lee (Ph.D thesis, 2005) Chromosomal aberrations Ionising radiation Primary lesions analysis of the frequencies of unstable aberrations by Giemsa staining translocation dicentric Fluorescence in situ hybridyzation (FISH) acentric fragments Micronuclei assay Biological dosimetry allows to asses an accidental dose of ionising radiation by analysis of changes induced in chromosomes of peripheral blood human lymphocytes. Lymphocyte Calibration curve • Established on the basis of the level of cytogenetic damage (chromosomal aberrations) induced by ionising radiation under in vitro conditions in human peripheral blood lymphocytes (PBL). • Used in biological dosimetry for retrospective dose estimation in case of accidental overexposure of people. CABAS Software designed for the purpose of biological dosimetry based on the analysis of chromosomal aberrations - dicentrics and rings, scored on Giemsa stained slides. Reference: Deperas J. et. al. (2007) CABAS - a freely available PC program for fitting calibration curves in chromosome aberration dosimeter. Radiat Prot Dosimetry 124:115-123, 2007. Methodology SCHEME OF THE EXPERIMENT for the standard metaphase analysis (dicentric assay) PHA Culture of Irradiated blood BrdU colcemid Fixation 0-24 h 46h 48-50h Reference: Cytogenetic analysis for radiation dose assessment. light microscope A manual. (2001) International Atomic Energy Agency. Vienna. Results 140 Number of dic+R per 100 cells 120 Mean values of aberration frequencies Fitted curves 100 80 60 40 20 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Dose [Gy} We established dose calibration curve for unstable chromosomal aberrations induced by therapeutic proton beam in the dose range from 0 to 3 Gy. Conclusion The calibration curve may be useful to retrospective dose estimation in case of accidental exposure to protons. References: • IAEA (1986) Biological dosimetry: chromosome aberrations analysis for dose assessment. International Atomic Energy Agency Technical Report No 260.Vienna. • IAEA (2001) Cytogenetic analysis for radiation dose assessment. A manual. International Atomic Energy Agency. Vienna.