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Content archived on 2024-04-15

PRODUCTION OF CHROMOSOME ABERRATIONS IN HUMAN LYMPHOCYTES BY IONIZING RADIATIONS

Objective

THIS RESEARCH CONTINUES THE THEME SUPPORTED BY THE COMMISSION IN THE PREVIOUS QUINQUENIUM. IT HAS THE OVERALL OBJECTIVE OF EXPLORING THE DOSE RESPONSE RELATIONSHIP BETWEEN THE PRODUCTION OF CHROMOSOME DAMAGE IN HUMAN LYMPHOCYTES AND RADIATION DOSE RATE AND QUALITY.
THE PROJECT IS AIMED AT ACCURATELY ESTIMATING THE FREQUENCIES OF DICENTRIC CHROMOSOMES IN HUMAN PERIPHERAL BLOOD LYMPHOCYTES TREATED IN VITRO WITH LOW DOSES OF X-IRRADIATION.

IN THE EVALUATION OF GENETIC RISK TO HUMANS DUE TO EXPOSURE TO IONIZING RADIATIONS, USUALLY DATA FROM HIGHER DOSES ARE EXTRAPOLATED TO LOW DOSES ASSUMING A LINEAR RESPONSE. DATA OBTAINED FOLLOWING EXPOSURE TO LOW DOSES OF RADIATION (<100 MGY), RELEVANT IN SITUATIONS OF OCCUPATIONAL EXPOSURE ARE RARE. THIS IS MAINLY DUE TO THE LARGE NUMBER OF CELLS NEEDED TO BE SCORED TO ARRIVE AT A RELIABLE ESTIMATE OF INDUCED ABERRATIONS. UNDER THE AUSPICES OF THE IAEA, A CO-ORDINATED RESEARCH PROGRAMME WAS INITIATED AND COMPLETED TO EVALUATE THE EFFECTS OF LOW DOSES OF X-RAYS IN THE DOSE RANGE OF 4.0-300 MGY. IN THIS EXPERIMENT BLOOD FROM TWO HEALTHY DONORS WAS USED AND ABOUT 70,000 CELLSWERE SCORED. INTERESTING FINDINGS WERE A REDUCTION IN THE FREQUENCIES OF ABERRATIONS AT 4.0 MGY, AND NO INCREASE IN THE FREQUENCIES OF ABERRATIONS UP TO 50 MGY. THE LATTER OBSERVATION IS ESPECIALLY INTERESTING; IT HAS IMPORTANT IMPLICATIONS FOR RADIOLOGICAL PROTECTION AND SHOULD BE CONFIRMED. SINCE THESE DATA WERE BASED ON BLOOD SAMPLES FROM TWO INDIVIDUALS, IT IS IMPORTANT TO VERIFY WHETHER THIS OBSERVATION IS UNIVERSAL. UNDER THE PRESENT PROGRAMME IT IS PLANNED TO ESTIMATE THE FREQUENCIES OF CHROMOSOMAL ABERRATIONS IN BLOOD SAMPLES FROM MORE INDIVIDUALS, INDUCED BY SIMILARLY LOW DOSES OF X-RAYS. SINCE RELIABLE SCORING OF LARGE NUMBERS OF CELLS IS ESSENTIAL, IT IS PROPOSED TO INCLUDE SEVERAL LABORATORIES WITHIN THE EEC FROM GERMANY, ITALY, BELGIUM, THE NETHERLANDS, AND THE UK IN THE PROGRAMME. THE IRRADIATION AND CHROMOSOMAL PREPARATIONS OF LYMPHOCYTES WILL BE MADE BY OUR LABORATORY AT NRPB, WHERE IRRADIATION FACILITIES, AS WELL AS ACCURATE PHYSICAL DOSIMETRY, ARE AVAILABLE. THE PREPARATIONS WILL BE CODED AND DISTRIBUTED TO THE PARTICIPATING LABORATORIES. IT IS PROPOSED TO SCREEN SEVERAL INDIVIDUALS' BLOOD IN THIS STUDY, AND IT IS ENVISAGED THAT THE WORK WILL BE COMPLETED IN TWO YEARS.
BLOOD WILL BE TAKEN FROM THE DONORS AND IRRADIATED AT 7 DOSES IN THE RANGE 3-300 MGY, TOGETHER WITH APPROPRIATE ZERO DOSE CONTROL SAMPLES. THE IRRADIATIONS WILL BE DONE AT NRPB, CHILTON USING 250 KVP X-RAYS AND BACKED UP WITH ACCURATE PHYSICAL DOSIMETRY.
THE BLOOD LYMPHOCYTES WILL BE CULTURED WITH BROMODEOXYURIDINE TO PERMIT FLUORESCENCE PLUS GIEMSA STAINING. CODED SLIDES WILL BE SENT TO THE PARTICIPATING LABORATORIES TO BE STAINED AND SCORED. 2500 CELLS PER DONOR PER DOSE WILL BE SCORED AND EACH OF THE 6 LABORATORIES WILL CONTRIBUTE 500 CELLS TO THIS TOTAL. THE DATA WILL BE COLLATED AND ANALYSED WITH COMPUTER PROGRAMMES WHICH ALREADY EXIST AT NRPB.

Topic(s)

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Call for proposal

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Coordinator

NATIONAL RADIOLOGICAL PROTECTION BOARD (NRPB)
EU contribution
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Address
CHILTON
OX11 0RQ DIDCOT
United Kingdom

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