[ RadSafe ] Benefit from ADJACENT Low-Dose Radiation: "Bystander effect"?
HOWARD.LONG at comcast.net
HOWARD.LONG at comcast.net
Thu Aug 21 18:27:46 CDT 2008
What is the proper term to describe the disappearance of a nasal cancer following
torso irradiation with 75 rem?
Examples of such beneficial stimulation of body defences (perhaps in the spleen lymphocytes)
are in a book shown me by Cuttler on the way to Palo Verde.
------------- Original message --------------
From: <Rainer.Facius at dlr.de>
> the mechanisms responsible for - the nowadays somewhat indiscriminately so
> called - bystander effects are manifold. They comprise both genuine short-range
> cell to cell communication via specific communication channels as well as less
> specific wide range signal transfer via universal 'second messengers', e.g., of
> the humoral system.
> Personally I reserve the more recent term bystander effect to those instances
> where cells which have received (very) low radiation doses signal their
> resulting response to cells of the same organ or tissue which have not received
> any radiation at all. The - usually few - cells 'hit' do transmit their signals
> via cell and tissue specific communication channels whose ordinary function
> (conceivably) is to ensure tissue homeostasis/control.
> For such instances as described by Mancuso et al. (2008) where the signals arise
> from cells rather heavily(!) exposed and where they affect cells in distant
> organs, I prefer the term abscopal effects - effects which have been described
> since decades before the genuine bystander effect. Although much of the
> communication system involved is yet to be elucidated the general endocrine
> system almost certainly is a mayor player.
> Contrary to the quoted statement by Brenner, these results have no import
> whatsoever on radiation protection at low doses. See also the corresponding
> remark from K S Parthasarathy, Mi 20.08.2008 11:56
> Regards, Rainer
> Dr. Rainer Facius
> German Aerospace Center
> Institute of Aerospace Medicine
> Linder Hoehe
> 51147 Koeln
> Voice: +49 2203 601 3147 or 3150
> FAX: +49 2203 61970
> Von: radsafe-bounces at radlab.nl im Auftrag von NIXON, Grant
> Gesendet: Mi 20.08.2008 22:09
> An: HOWARD.LONG at comcast.net; ROY HERREN; radsafe at radlab.nl
> Betreff: RE: [ RadSafe ] Danger of ADJACENT HIGH-Dose Radiation
> To add to Howard's comment:
> Perhaps the mechanism for the DNA damage to adjoining tissue (the
> so-called "bystander effect") is nothing more than a propagated
> free-radical reaction having nothing to do with cell-to-cell
> communication. The high doses would liberate such large numbers of
> free-radicals that the affected perimeter of affected tissues would
> increase on physical grounds alone (diffusion theory coupled with target
> theory). The "chemical that blocks cell-to-cell communication" may
> simply be a free-radical scavenger.
> Grant I. Nixon, Ph.D., P.Phys.
> Science Specialist (Dosimetry/Physics/Engineering)
> BEST Theratronics
> 413 March Road
> Ottawa, ON K2K 0E9
> tel. (613) 591-2100 x2869
> fax. (613) 591-2250
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