X-Message-Number: 3899
From: Eugen Leitl <>
Newsgroups: sci.cryonics
Subject: Re: glycerol questions
Date: Thu, 23 Feb 1995 18:06:06 +0100
Message-ID: <>
References: <> <>


On Wed, 22 Feb 1995, Michael Clive Price wrote:

> I am trying to see how Suda's experiments with cryopreservation of cat
> brains [*] relates to cryopreservation as performed today (on humans). 
> Suda states that he perfused his brains (the cats', not his, that is)
> with 15% glycerol by volume.  How does this translate into terms of
> molarity?  If someone knows and can explain the answers that would be
> great.

Polyol/water mixes volumes are not additive. But volume % is refered
to the volumes before mixing. Look up the density of glycerol, compute
the mass from volume, compute molarity from it and the glycerol molar 
mass. Concentration units are mol/l. (If you don't have the numbers at
hand (try rubber book) I can look them up for you.)

Apropos glycerol, is dimethylsulfoxide used in modern commercial
cryoprotecting agents? Maybe DMSO/glycerol mixes? Additionally,
it would be extremely interesting to learn what methods/sequences
are used by commercial cryosuspension companies. I hope this isn't
classified or any such thing? A simple outline would suffice.
Especially, the following issues are of interest:

1) Is the blood removed during cryoprotectant infusion?
2) Must the body be precooled? (say, 4 degree Celsius).
3) Is oxygene/glycose provided during cryoflood to counteract 
   brain damage? What is the maximum tolerable process time?
4) What is the temperature program for whole body/brain only
   freeze?
5) Is brain tissue frozen en block? (Would cutting up
   introduce too many artefacts?)
6) Is process/result monitored? Are freeze damage estimations
   done? (xRay diffraction, bioactivity of a thawed sample, etc.)
7) Is liquid nitrogen temperature enough? Is an inert gas blanket
   used against tissue oxidation?
8) Is the current policy to minimize preprocessing or vice versa
   and are the deviations protocolled? Is a copy stored with the
   the tissue?
9) Is there any noticeable research on cryomethods going on
   in the companies? How is it financed? Any breakthroughs?
10) Are legal problems real problems? _Is_ the legal status
   of cryosuspended person "deseased"? Any indications of
   change?

Yes, these are a lot of hard questions. Yet I think that by answering
them the cryosuspension firms would show a greater transparency
and thus gain a higher credulity level.

> 
> Ta.
> 
> Michael Price                        
> 
> [(] Isamu Suda, Kyoko Kito and Chizuko Adachi _Viability of Long Term
> Frozen Cat Brain in vitro_ in Nature, Vol 212, 268-270 (1966) and
> _Bioelectric discharges of isolated cat brain after revival from years
> of frozen storage_ in Brain Research Vol 70, 527-531 (1974)



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