1. Laboratory of Radiation Biology

2. Chromosomal analysis for calibration curve creation for potential retrospective dose estimation

3. Egyptian Candidates
Nadia Abdrabo Samak Fayrouz Sayed Ahmed

4. Supervised by
Dr. Polina Kutsalo
Dr. Anna Rzjanina

5. Contents Aim of our work Introduction Methodology Results Conclusion
References

6. 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.

7. Introduction

8. 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.

9. Chromosome structure

10. DNA and Histone proteins are packaged into structures called chromosomes.

11. Cell Cycle

12. Shapes of different stages of chromosomes under microscope

13. (a) S-phase (b) Early G2-phase (c) Late G2-phase
(d) Metaphase (e) Anaphase (f) G1-phase
The problem is that PCC method worsens the appearance of chromosomes. Centromeres are invisible and analyze of dicentrics is impossible. Therefore there are excess fragments or only rings can be scored.
Calyculina induced PCC in cells within all cell stages, therefore the most important is to recognize cells in G2 and M stages. The M cells look quite normally and even dicentrics can be visible but in G2 cells we can see only DNA fragments and only distinct rings can be analyze.
Courtesy of R.Lee (Ph.D thesis, 2005)

14. Chromosomal aberrations
Ionising radiation
Primary lesions
analysis of the frequencies
of unstable aberrations
by Giemsa staining
acentric
fragments
Fluorescence in situ
hybridyzation (FISH)
translocation
dicentric
Micronuclei assay

15. Biological dosimetry allows to asses an accidental dose of ionising radiation by analysis of changes induced in chromosomes of peripheral blood human lymphocytes.
Lymphocyte

16. 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.

17. 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: , 2007.

18. Methodology

19. SCHEME OF THE EXPERIMENT
for the standard metaphase analysis (dicentric assay)
PHA
Culture of Irradiated blood
BrdU
colcemid
46h
Fixation
0-24 h
48-50h
Staining with Fluorescence Plus Giemsa (FPG)
Reference: Cytogenetic analysis for radiation dose assessment.
A manual. (2001) International Atomic Energy Agency. Vienna.
light microscope

20. Results
We established dose calibration curve for unstable chromosomal aberrations induced by therapeutic proton beam in the dose range from 0 to 3 Gy.

21. Conclusion
The calibration curve may be useful to retrospective dose estimation in case of accidental exposure to protons.

22. 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.

23. Thank You