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Essentials of Biodosimetry Aberrations Analysis Techniques

Learn about dicentrics, micronuclei, translocations, and PCC rings used in biodosimetry analysis. Understand their features and requirements for accurate results. Proper blood sampling and packaging for transportation are also covered in this lecture module.

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Essentials of Biodosimetry Aberrations Analysis Techniques

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  1. Basics of BiodosimetryPart 2 Lecture Module 3

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

  3. The dicentric F D A dicentric and its fragment

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

  5. The centric ring R D R

  6. 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

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

  8. Essential features Micronucleus • Needs 72h 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

  9. The translocation A reciprocal translocation

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

  11. 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

  12. Fusion PCC The condensed human chromosomes are single stranded

  13. Fusion PCC Stained to highlight centromeres and thus dicentrics

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

  15. PCC rings

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

  17. Summary of the assays

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

  19. 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

  20. 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

  21. 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

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

  23. Blood sampling for biodosimetry (6)

  24. 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

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