AW: AW: [ RadSafe ] dose RATE of ANY Medicine is the decisive variable
Rainer.Facius at dlr.de
Rainer.Facius at dlr.de
Fri Sep 8 09:53:58 CDT 2006
On the atomic/molecular level there may be a certain fraction of primary lesions (altered molecules) which do not arise in 'normal' cell metabolism - though of course I would refrain from claiming that we know ALL about 'normal' metabolisms. Experimentally we know that densely ionizing radiation such as heavy ions produces qualitatively - in contrast to quantitatively - different species of altered/damaged molecules (which by the way - apart from other reasons -invalidates the concept of RBE). To the extent that some fraction of deposited energy even from 'sparsely' ionizing radiation leads to spatial and temporal dense concentrations of ionizations it is not unreasonable to claim that also under low LET radiation molecular damage may ensue which does not/cannot arise in 'normal' metabolism.
Nevertheless, the prime message of virtually all findings of the recent 'new radiobiology' in my view is:
"Abandon hope all ye target theory modelers: on the effects of low dose exposures to ionizing radiation and other carcinogens" [Jeffrey L. Schwartz, Mutation Research 568(2004)3-4]
Viz, the initial molecular damage (even that to DNA) is in NO WAY predictive for the final biological result, (already) on the cellular level, but definitely on the tissue, organ, and whole system level. So I would discard - unless SPECIFIC molecular species and their SPECIFIC pathways would be invoked - this
"Yeah, but radiation is different."
as the irrelevant hand-waving pseudo argument that is, reflecting (with hindsight) the state of knowledge 20+ years ago.
Kind regards, Rainer
Von: radsafe-bounces at radlab.nl im Auftrag von Ted Rockwell
Gesendet: Do 07.09.2006 21:43
An: Muckerheide-MA; Muckerheide-home; Facius, Rainer; Raabe, Otto; Long, Howard; radsafe at radlab.nl
Cc: Rad-Sci-L; Rad_Sci_Health at yahoogroups.com
Betreff: Re: AW: [ RadSafe ] dose RATE of ANY Medicine is the decisive variable
I understand that much (I think), but is there a real biological, and
logical, basis for saying that the processes involved in radiation damage
(and healing, or progression to cancer) are of a fundamentally different
kind than damage from metabolism or other stimuli? For if they are, then
the whole Pollycove/Feinendegen argument fails. I think a lot hangs on the
validity, or invalidity of the argument (that seems to trump all others)
that ³Yeah, but radiation is different.²
I¹d like to get really clear on that.
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