X-Message-Number: 12487
Date: Fri, 1 Oct 1999 08:43:59 -0700 (PDT)
From: Doug Skrecky <>
Subject: for Thomas Donaldson

In Message #12479 Thomas Donaldson wrote:

> I think that the earliest technology to be used
> in cryonics in a widespread way will be cryopreservation, that this will
> be followed by the vitrification methods developed by 21st Century 
> Medicine,
>
 I think it likely not a coincidence that 21CM seems to be focusing 
on ether derivatives of ethylene glycol. As I have mentioned before
ethylene glycol is the conventional cryoprotectant with the highest
permeation into tissue, and as a result is the most promising agent 
for whole organ cryopreseration discussed on Medline.

> and that someday we will have a fixative which preserves us 
> without any need to keep the bodies especially cold.
>
 I'd just like to mention again that chemical fixation by itself is not
sufficiant for long term stable storage. This can only be obtained 
by reducing storage temperature below its glass transition.
Reversible fixation would be of great value as a means to allowing 
sufficient time for high molecular weight lyoprotectants to penetrate 
tissue, without significant deterioration occurring in the meantime. 
I expect some techniques for increasing the permeability at least
temporarily would also need to be used.
 If sugars such as sucrose are used storage temperatures could be at room
temperature. Is sugar alcohols such as sorbitol are used, (which are
easier to get into cells), storage temperature will need to be below -9 C,
but even here dry ice temperatures would not be needed. Of course to
maintain stable glasses complete dehydration is needed, and the addition
of moisture scavengers such as calcium oxide inside storage containers
would be required as a safety precaution.
 However unlike at liquid nitrogen temperatures, even glasses are not
completely stable in the presence of oxygen gas, so the same precautions
about moisture need to be repeated for oxygen as well.

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