X-Message-Number: 3208
From: Brian Wowk <>
Date: Tue, 4 Oct 94 16:15:59 CDT
Subject: SCI.CRYONICS.Fixation,etc.

Ian Taylor:

>Recently Steve Bridge wrote:

>>My personal, non-official guess, is that within 50 years it will be
>>possible for a living, healthy human being to be placed in some form of
>>very-long term (if not technically "permanent") biostasis and be revived
>>with no ill effects.
>Thanks for for non-official guess Steve ;) and for such a unexpectedly
>full response. With all respect Steve your answer was not to the question I
>was trying to ask. Let me clarify. My question is far less demanding on our
>technology. I am not requiring initially a reversible process; only damage-
>free entry into biostasis, the critical first step as I see it. We then rely
>on future technology to restore function etc. To me this is *the* question:
>how far away is our current technology from an ideal biostasis technique.

	I realize your questions are directed at Steve Bridge, but I 
thought I'd take a stab at them anyway.  I agree completely with 
Steve's estimate of 50 years as the likely timeline for achieving 
demonstrably reversible suspended animation, and I suspect we 
agree on most other issues here as well.

	You ask about achieving "damage-free" entry into biostasis.  
This is a bit of an oxymoron because human beings (as currently 
designed) with stopped metabolism are inherently damaged, and 
have no way of spontaneously regaining function.  I assume you 
are really asking when will we have a technique that we are certain 
is reversible with future technology.  The answer is that we really 
won't know for *certain* until we can actually revive the person.

	 The above point is very relevant to your questions about 
fixation.  There are some good arguments in favor of 
supplementing freezing or vitrification with chemical fixation.  
The problem with fixation is the lack of feedback.  Frozen or 
vitrified cells will often spontaneously recover function after 
rewarming.  The extent of functional recovery is a direct measure 
of the success of your preservation procedure.  In fact, we are 
probably less than 5 years and a million dollars or so away from 
achieving full functional recovery of *entire brains* from -130'C 
using vitrification only.  What happens now if you chemically fix?  
Well, you lose all possibility of using function to measure 
preservation integrity, and virtually guarantee that your patient 
will need full-blown nanotechnology for recovery.  This is why 
fixation is not used in cryonics.  It's too risky, with too little 
feedback.

> A table like this would help me to understand the current
> state of practice, perhaps you can correct and complete it:

>    Biostasis       Damage due      Duration of
>    Technique       to technique    Biostasis       Notes
 
>    Cremation       100%            N/A             For completeness ;)
>   Burial          99%             100 years?      Bones, DNA only ... ?
>    Dry Ice         5%?             1 year?         Old technique
>    Vitrification   1%?             Indefinite?     Current technique?
>   Fixation & Vit. 0.1%?               "           Proposed    "
>   Ideal           0%              Indefinite      Complete preservation
 
>WARNING the above table is for discussion purposes only, and 
>most likely has no resemblance to fact.

	Damage mechanisms in any of the above procedures are 
multi-dimensional and cannot be characterized by a single 
number.  Cryoprotected (glycerolized) freezing is the current state 
of the art in cryonics.  Resulting damage includes cell dehydration, 
disruption of cell-to-cell relationships, torn membranes, protein 
denaturation and possibly macroscopic fractures.  The literature 
and sign-up paperwork of Alcor and CryoCare contain extensive 
discussions of these effects.  Most of these problems go away if 
vitrification is used instead of freezing.  However vitrification is at 
least a decade away from practical implementation, and even then 
will only be used on a single organ (the brain).   

	Thank you for your interest.


					--- Brian Wowk
					    Patient Care Director
					    CryoCare Foundation

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