Basics of Biodosimetry Part 2 Lecture Module 3

Basics of Biodosimetry Part 2 Lecture Module 3 IAEA International Atomic Energy Agency

What aberrations do we analyse • • Dicentrics (and rings) Micronuclei in binucleate cells Translocations by the FISH method Fragments and rings in prematurely condensed chromosomes IAEA 2

The dicentric F D IAEA A dicentric and its fragment 3

Essential features Dicentric • Most experience – the ‘gold standard’ • Ideal for use soon after the accident • Needs 48 h cultures • Needs skill in analysis IAEA 4

The centric ring R D R IAEA 5

Essential features Centric ring • Seen in the dicentric preparations • Induced too rarely to be used alone as a biodosemeter • Can be combined with the dicentrics during analysis IAEA 6

The micronucleus Binucleate cells with zero, one and two micronuclei IAEA 7

Essential features Micronucleus • Needs 72 h cultures • Less skill required in analysis • Faster analysis than dicentric • Not so accurate at low doses as dicentric • Unless combined with FISH centromere probe but slower and more expensive slide processing IAEA 8

The translocation IAEA A reciprocal translocation 9

Essential features Translocation • Better for older exposures • Better for delayed discovery high doses • Needs 48 h cultures • More expensive than dicentric • Slide processing more complicated • Needs skill in analysis IAEA 10

Premature Chromosome Condensation (PCC) Purpose: To cause the chromosomes to condense at stages of the cell cycle when the chromatin is normally diffuse. Why: Because aberrations can only be observed in the condensed state How: Two methods: • fusion to a mitotic cell • chemically induced IAEA 11

Fusion PCC The condensed human chromosomes are single stranded IAEA 12

Fusion PCC Stained to highlight centromeres and thus dicentrics IAEA 13

Essential features Fusion PCC • Very rapid- results ready in ~5 h from receipt of sample • No culturing needed • Technically difficult • Needs skill in analysis • Images can be equivocal IAEA 14

PCC rings IAEA 15

Essential features PCC ring • Needs culturing • Technically as easy as the dicentric • Suited for exceptionally high doses >10 Gy IAEA 16

Summary of the assays IAEA 17

Blood sampling for biodosimetry (1) Basics: • A 10 ml blood sample • In lithium heparin anticoagulant IAEA 18

Blood sampling for biodosimetry (2) Timing: • 24 hours after the exposure is best • If later, as soon as possible • Before any confounding treatments such as transfusion IAEA 19

Blood sampling for biodosimetry (3) Transporting blood: • Transit times of 2 -3 days are OK • Avoid excessive temperatures during transit • Avoid security x-rays during transit IAEA 20

Blood sampling for biodosimetry (4) Packaging: • Blood is considered as a bio-hazard • National regulations may apply for mailing • International regulations exist for air transport IAEA 21

Blood sampling for biodosimetry (5) Packaging that conforms to the UN regulations is available commercially IAEA 22

Blood sampling for biodosimetry (6) IAEA 23

Conclusions This lecture has introduced: • Various types of aberrations that are used for biodosimetry • will be addressed more fully later in the course • Essential features of different aberration assays • Correct blood samples needed for biodosimetry • Packaging requirements for transporting blood IAEA 24