Chromosome analysis for calibration curve creation for potential...
Transcript of Chromosome analysis for calibration curve creation for potential...
Chromosome analysis for calibration curve
creation for potential retrospective dose estimation
Joint Institute for Nuclear Research
Laboratory of Radiation Biology
Students Gijana S.
Ngoepe PNM.
Seepei LE.
Supervisor Dr. Kutsalo P.
OUTLINE
Aim
Introduction
Methodology
Results
Conclusion
Acknowledgements
AIM
Creating calibration curve for retrospective dose estimation, on
the basis of the frequencies of unstable chromosomal aberrations
induced by the proton beam used in cancer therapy at the
Laboratory of Nuclear Problems at JINR.
INTRODUCTION
Introduction
There have been numerous radiation accidents:
• Hiroshima & Nogasaki, Japan, 1945
• Semipalatinsk, USSR, 1949-1963
• Chernobyl, USSR, 1986
• Tokia-Mura, Japan, 1999
• Byalujstok, Poland, 2001
Application of ionising radiation has increased.
Biological dosimetry allows assessing of dose of radiation by
analysis of damages induced in chromosomes of human peripheral
blood lymphocytes.
Lymphocytes Close correspondence between aberrations induced
in lymphocytes in vivo and in vitro.
Lymphocytes are type of cells found mainly in a DNA
presynthetic stage of a cell cycle.
Lymphocyte
Chromosomes
Chromosomes-
contain genetic
material, which makes
organisms what they
are.
DNA - main cell
target for the action of
ionising radiation.
Cell cycle
Cell cycle - events
that occur from the
completion of one
division until the
next completion of
one division of a cell.
In metaphase, centromeres are clearly visible and
analysis of dicentrics is possible.
(a) S-phase (b) Early G2-phase (c) Late G2-phase
(d) Metaphase (e) Anaphase (f) G1-phase
Chromosomal aberrations Different aberrations that can be observed on metaphase
analysis are dicentrics, centric rings, acentric rings,
chromosome fragments, chromatid breaks, etc.
Centric ring
Acentric
ring
Dic
METHODOLOGY
EQUIPMENT
Lithium
heparin tubes
Proton
irradiator
Incubator
Laminar
air flow
cabinet Pipette Centrifuge Light microscope
Isolation of lymphocytes
• Studies can be done on either whole blood or isolated
peripheral blood lymphocytes
Isolation of lymphocytes Checking the spread of chromosomes before staining
Working under sterile conditions
SCHEME OF EXPERIMENT Standard Metaphase Analysis (unstable aberrations)
Colcemid
47h
Fixation
48-50h
Observation using
light microscope
Culture of
Irradiated
blood
PHA
0h
RESULTS AND DISCUSSION
RESULTS
Results as measured by students
RESULTS
Results as measured by Dr. Kutsalo
CONCLUSION
The number of aberrations is dependent on the radiation dose
The retrospective dose can be determined from the number of
aberrations using the calibration curves that we have created
ACKNOWLEDGEMENTS
Dr. Mkaza
Prof. Lekala
Mr. Malaza
Dr. Kutsalo
National Research Foundation
Department of Science and Technology
Joint Institute for Nuclear Research
Thank you!