[ RadSafe ] Benefit from ADJACENT Low-Dose Radiation: "Bystander effect"?

[HOWARD.LONG at comcast.net]

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.

Howard Long

------------- Original message -------------- 
From: <Rainer.Facius at dlr.de> 

> Grant, 
> 
> 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 
> GERMANY 
> 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 
> Canada 
> tel. (613) 591-2100 x2869 
> fax. (613) 591-2250 
>