X-Message-Number: 13850
Date: Tue, 6 Jun 2000 10:09:34 -0700
Subject: re: Higher Temp Storage
From: Ivan Snyder <>

Hi Mike and all,

>Message #13843
>Date: Mon, 05 Jun 2000 07:31:31 -0700
>From: Mike Perry <>
>In view of Doug Skrecky's posting, #13841, we can ask of the higher
>temperature storage that has been proposed as an accompaniment of a new
>suspension protocol would really be best for longterm preservation of
>identity-critical information. The higher-temperature storage may indeed
>lead to reversible cryopreservation, yet over many decades it could
>promote degradation of memory information in the brain that would not
>at liquid nitrogen temperature. The cracking that occurred in lowering
>this temperature might still be a favorable tradeoff. Something to
>investigate. Actually, though, I am inclined to optimism about storage
>brain tissue at -130, in view of the successes Suda had with brainwave
>recovery at the much higher storage temperature of -20.

Ivan here,
I offer my perspective as one who studies biology. I find it most easy to
infer from nature to deduce what is feasible. We already know what
cryosuspension protocol works; that which mimics already working systems.
There are many creatures which naturally undergo seasonal freezing. These
range from the most simple organisms to the more complex. The most
complex and most similar physiologically to us which freeze and revive
are I believe frogs. I can't recall for sure now what sort of
cryoprotectant the frogs have, but I know that insects produce glycerol,
which is what is also used in human cryosuspensions. I have read that
although alot of insects do survive freezing and thawing, there is a
minimum temperature limit which they can tolerate, lower and they are
killed. This is because glycerol, like any other substance, has a
freezing point. Glycerol merely lowers the freezing point. I think the
insects would sustain internal freeze fractures at temps even higher than
that at which dry ice sublimes.

Considering the freezing point of glycerol, it seems to me that immersion
in liquid nitrogen defeats the purpose. I imagine that the vitrification
process is meant to get around this, but I understand that the chemicals
involved are toxic. I see a benefit in the use of liquid nitrogen; the
system is more easily maintained, less fear of breakdown, and is cheaper
than with a refrigerator. Still, temperatures regulated by a refrigerator
at -20 most closely matches the natural *working* cryosuspension systems
seen in the insects. These seem like good reasons for re-examining

Ivan Snyder
Hermosa Beach
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