X-Message-Number: 3359
From: Brian Wowk <>
Date: Thu, 27 Oct 94 01:48:29 CDT
Subject: SCI.CRYONICS Fixation, reply to Ralph Merkle

Ralph Merke:
> The use of chemical fixation is debated from time to time and would
> seem to offer definite advantages.  Current suspension methods do
> not preserve function, and the evidence that they preserve structure
> is at present based largely on light and electron microscopic images.
        I think it is a bit misleading to say current suspension
methods do not preserve function.  While they do not preserve
function of the brain as a whole, they almost certainly preserve
unit (cell) function.  Alcor's monograph, The Cryobiological Case
for Cryonics, is full of references to work where glial cells or
fetal brain tissue were successfully recovered and cultured after 
being frozen with *really lousy* cryoprotection protocols down to
-196'C.  Although adult neurons cannot be cultured because they no
longer divide, synaptosomes from adult neurons resume metabolism and
neurotransmitter uptake after thawing from -196'C.  (Aside: What is 
really amazaing is that in some of these studies, the brains had been 
dead at room temperature for serveral hours before they were frozen!)
        Just because neither freezing or fixation preserves function
of the brain *as a whole*, does not mean they are equivalently damaging. 
The havoc wrecked by fixation on the molecular level is devastating
compared to freezing.  The only possible advantage of fixation might  
be a reduction of mechanical damage from ice crystals.  However I
don't know how significant this protection would be, and more to the
point I don't think any of us know how significant such protection
would be from the standpoint of protecting memory storage.
        Present cryonics techniques preserve cellular chemistry and
functionality fairly decently.  We are also now tantalizingly close to
technology for preservation the brain without any damage at all.   
Under the circumstances, I think research oriented toward fixation 
would be a step backward.
--- Brian Wowk

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