RE: Stable Reciprocal Translocation Blood Test

["Pickett, Bruce D" <Bruce.Pickett@PSS.Boeing.com>]

Sara,

Thanks for the terriffic information.

I understand that dicentric chromosomal tests can detect doses greater
than about 15 Rad (0.15 Gy) whole body at a 95% confidence level. Do you
know what the sensitivity for the translocation test is? Is there any
reason for choosing the dicentric test over the translocation test, or
vice versa?

Thanks,

Bruce Pickett
bruce.d.pickett@boeing.com

> ----------
> From: 	Carlisle, Sara[SMTP:carlisles@aecl.ca]
> Sent: 	Monday, March 02, 1998 8:28 AM
> To: 	'radsafe@romulus.ehs.uiuc.edu'
> Cc: 	'Bruce.Pickett@PSS.Boeing.com'
> Subject: 	RE: Stable Reciprocal Translocation Blood Test
> 
> Bruce:
> 
> A stable reciprocal translocation blood test looks at the frequency of
> "reciprocal translocations" in circulating white blood cells.  In
> cells,
> the genetic material, DNA, is packaged into sub-units called
> chromosomes. When DNA is damaged there can be rearrangement of these
> sub-units, leading to events collectively known as chromosomal
> aberrations. Certain classes of chromosomal aberrations (i.e.
> reciprocal
> translocations) are stable and can be used to determine lifetime
> cumulative radiation exposures. Other chromosomal aberrations, such as
> dicentric chromosomes, can be used to assess recent exposures - these
> aberrations are not stably inherited, since they affect partitioning
> of
> genetic material between daughter cells during cell division.
> Chromosomal aberrations are the end-points traditionally measured in
> biological dosimetry and have, for example, been used extensively in
> studies of the Japanese Atomic Bomb survivors. 
> 
> To measure chromosomal aberrations, white blood cells are isolated
> from
> a blood sample, stimulated to divide (with PHA - phytohaemagglutanin)
> and then treated with a chemical (colcemid) to stop cell division at a
> point where individual chromosomes can be seen (metaphase).  The
> chromosomes are stained with dyes, and examined by a cytogeneticist
> who
> looks for abnormal chromosomes. Recent advances in molecular biology
> allow specific chromosome pairs to be stained with dyes that
> differentiate them from the remaining chromosomes (chromosome
> painting),
> which makes detection of reciprocal translocations much easier than
> traditional non-specific staining techniques, which relied on
> recognition of changes in complex banding patterns on the chromosomes
> for detection of chromosomal abnormalities - a very tedious exercise
> that required a very experienced cytogeneticist.
> 
> Hope this helps. I'm not actually doing these assays myself, but staff
> here at AECL are doing research involving reciprocal translocation
> assays on blood samples.  If my explanation is too full of molecular
> biological jargon, let me know and I'll give it another shot.
> 
> Sara Carlisle
> Radiation Biology and Health Physics Branch
> Chalk River Laboratories
> 
> phone (613) 584-8811 extn. 3667
> email carlisles@aecl.ca
> 
> > ----------
> > From: 	Pickett, Bruce D[SMTP:Bruce.Pickett@PSS.Boeing.com]
> > Sent: 	March 2, 1998 10:42 AM
> > To: 	Multiple recipients of list
> > Subject: 	Stable Reciprocal Translocation Blood Test
> > 
> > Does anyone know what a "stable reciprocal translocation blood test"
> > is?
> > Please provide any details which you can think of in your response.
> > 
> > Bruce Pickett
> > bruce.d.pickett@boeing.com
> > 
>