[ RadSafe ] Re: Universal Hormesis mechanisms in vivo?

[John Jacobus]

Jim,
Thanky you for clarifying the issue and keeping it
focused.  I wish others would do the same and not
bring in other issues not relavant to the topic.  

The reference to stress response protein I think is a
good example of the situation.  I think that is also
important to remember that a response may be neither
"good" nor "bad."  Again, the difference between a
causual relationship and a casual relationship.  

I am not sure if citing a 1920 paper is really
relivant to what we do today.  Bone marrow surpression
is a common fact.  That is one of the reason we use
focused external radiation beams.  It is still a
significant concern in chemotherapy and radionulide
therapy like I-131 ablaiton therapy.

--- "Muckerheide, James" <jimm at WPI.EDU> wrote:

> Hi John,
> 
> You are right, but this relates to the point we've
> been making for 10 years
> or so:  The biological responses to stresses are
> intrinsic to biology.  
> 
> Stress response is not unique to each stressor.  The
> stress protein HSP70
> (heat shock protein) is stimulated in many cases. 
> It is also shown to apply
> to heat, and exercise, and to many psychological
> stresses, and to heavy
> metals, etc., etc.
> 
> It would be unlikely (or unbelievable) if biology
> responded differently to
> radiation, with stimulation at low doses and
> suppression at high doses.  (Not
> all suppression is "bad," e.g., heavy exercise in
> the damage-repair regime,
> and not all stimulation is "good."  But we know that
> the specific responses
> to radiation are generally a net-positive effect on
> the biological and
> physiological functions of an organism - and why
> cellular studies are
> generally irrelevant to understand low vs. high dose
> effects to an organism,
> even though it may be informative about (some)
> mechanisms.)
> 
> It is also the case that the stimulation of specific
> genes, proteins,
> enzymes, and effects on immune cells, etc. are
> entirely DIFFERENT when
> exposed to a low dose vs. a high dose.  In some
> cases the response at a low
> dose is stimulated vs. suppressed, or the opposite;
> and in some cases totally
> different genes are stimulated at high vs. low
> doses.  This means that a
> biological "linearity" isn't possible, with
> responses 'similar' but reduced
> at low vs. high doses.  Biological and physiological
> responses are entirely
> different in immunological whole organisms at low
> vs. high doses. 
> 
> Remember Murphy (PNAS 1920) stimulating vs.
> suppressing lymphocytes at lower
> vs. higher doses? Causing dramatic decreases instead
> of increases of cancers
> vs. controls:
>
http://cnts.wpi.edu/rsh/DD3/Murphy20PNASResistMiceCa!.pdf
> 
> (just a couple of pages).
> 
> Regards, Jim 
> 
> 
> > -----Original Message-----
> > From: radsafe-bounces at radlab.nl
> [mailto:radsafe-bounces at radlab.nl] On
> > Behalf Of John Jacobus
> > Sent: Friday, November 04, 2005 1:28 PM
> > To: howard long
> > Cc: radsafe; rad-sci-l at WPI.EDU
> > Subject: [ RadSafe ] Re: Universal Hormesis
> mechanisms in vivo?
> > 
> > Howard,
> > Antigens are biological and alpha-benzene
> > hydrochloride is a chemical.  Ionizing radiation
> is a
> > form of energy.  The response may not be the same.
> > 
> > I assumed that you knew the differences.  By the
> way,
> > you do know about the placebo effect?
> > 
> > 

+++++++++++++++++++
On Oct. 5, 1947, in the first televised White House address, President Truman asked Americans to refrain from eating meat on Tuesdays and poultry on Thursdays to help stockpile grain for starving people in Europe. 

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com


		
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