AW: AW: [ RadSafe ] cancer is the result of defective tissue/immunecontrol

[Rainer.Facius at dlr.de]

"By the way, why do you think microgravity causes immuncompetency? Certainly not the lack of radiation. How about the decalcification?"

Dear John:

The primary cause of impaired immunocompetence under prolonged weightlessness is supposed to be a systemic response to internal fluid shifts and associated (after an adaptation period persistent) changes of the humoral status, salt balance, ... . Mechanisms are still mostly hypothetical, e.g. regarding kidney involvement, as are putative receptors and signal chains already on a cellular level. Bone metabolism to my knowledge has not yet been causally associated with reduced immunocompetence.

Kind regards, Rainer




________________________________

Von: John Jacobus [mailto:crispy_bird at yahoo.com]
Gesendet: Fr 30.06.2006 20:10
An: Facius, Rainer; radsafe at radlab.nl
Betreff: Re: AW: [ RadSafe ] cancer is the result of defective tissue/immunecontrol



Rainer,
I do know what I should reconsider.  That the immune
system does not recognize the tumor as foreign? 

It is apparent that tumors and cancers are conditions
of old age.  One idea is that the cells that make up
the tumor change do not atrophy as they should, so the
immune system still recognizes the tumors as self.
The alternative is the immune system is weakened and
cannot attack the tumor.  Of course, in a young
person, the immune system should be "strong," but
still the tumor develops.  Interesting question, don't
you think?  COuld it be that there may be more than
one mechanisms? 

I suggest you ask your friend what he means.  I would
remind you that the Kim paper really only considers
one type on tumor in a non-human model.  It may not
represent the results in other murine tumors, or in
humans.  Biology is not like physics.  One equation
may not fit all cases. 

By the way, why do you think microgravity causes
immuncompetency?  Certainly not the lack of radiation.
How about the decalcification?

--- Rainer.Facius at dlr.de wrote:

> John:
>
> This very Thursday I was discussing with the head of
> our Institute - a medical Professor holding also the
> chair of Aerospace Medicine of our very prestigious
> University RWTH Aachen - the curriculum for a new
> Course on Space Medicine in our institute.
>
> Among the topics in physiology, the altered
> immunocompetence in microgravity was assigned to an
> extra lecture. Without thinking about my post I drew
> his attention to the fact that - according to
> recently emerging empirical evidence - such
> alterations might well affect seriously our space
> radiation cancer risk estimates, e.g. for planned
> missions to Mars if indeed - as I surmised -
> tumourigenesis were significantly controlled (also)
> by the immune system. In response he looked at me
> with an expression of astonishment and (in essence)
> said:
>
> "Well, this is really an old hat!"
>
> In other words, for him - the Professor of Medicine
> - these exciting observations by Kim et al. provide
> just an animal-experimental corroboration of matters
> of fact which for man are already established.
>
> I in turn was surprised seeing him consider this as
> a matter of course and was not prepared to argue
> against it. I certainly will pick up this topic on
> the next occasion with him and you as well might
> wish to reconsider it.
>
> Kind 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
>
> -----Ursprüngliche Nachricht-----
> Von: radsafe-bounces at radlab.nl
> [mailto:radsafe-bounces at radlab.nl] Im Auftrag von
> John Jacobus
> Gesendet: Donnerstag, 29. Juni 2006 23:20
> An: Facius, Rainer; radsafe at radlab.nl
> Betreff: Re: [ RadSafe ] cancer is the result of
> defective tissue/immunecontrol
>
> Rainer,
> As you note, at least in murine gastrointestinal
> cancer (sic) this is true.  However, I do not think
> you can say this about other cancers.  I guess you
> could, but do you think all cancers are due to
> defective tissue/immune control?  It is a question
> of recognition of "self," e.g., cancers are
> recognized as normal tissues, which they are to the
> immune system.
>
>

+++++++++++++++++++
"You get a lot more authority when the workforce doesn't think it's amateur hour on the top floor."
GEN. MICHAEL V. HAYDEN, President Bush's nominee for C.I.A. director.

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

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