X-Message-Number: 3812
Date: Tue, 07 Feb 1995 12:33:20 GMT
From:  (Michael Clive Price)
Subject: Re: CryoNet #3787 - #3793

I have some questions for Robert Ettinger and others about the sheep
head experiments that CI have been conducting, in particular about how
their experimental procedures differ from Alcor's.

Robert mentions that CI used a slower cool-down (a week to get down to
dry-ice temperatures) and warm-up than usual and speculates that the
apparent lack of cracking (to be confirmed shortly, it seems, on slides
coming over from the Ukraine) may be due to this.  In Robert's most
interesting presentation, covering the past and looking to the future
of cryonics, to the Sixth Annual Venturist Festival, reprinted in
Alcor's _Cryonics_ (3rd quarter 1994) Robert also says that CI had
previously experimented with using a different cryoperfusion technique
-
- namely loading in the glycerol-based cryoprotectant all in one go (if
I may phrase it so) rather than slowly building up the concentration,
which I believe is more conventional -- and that the Ukraine experiments
were designed to replicate this particular feature as well.  Since there
was only mention of the slower cool-down and warm-up in Robert's latest
report my first question is to ask whether the Ukraine sheep head
experiments also used the "all in one go" approach to loading up the
glycerol-based cryoprotectants.  If so I wonder whether Robert could
comment on the possibility that this may be the (putative) cause of the
lack of cracking?  (Admittedly the slow cool-down sounds the more likely
cause, but I wonder if there is any evidence for this plausible
explanation.)  What was the molarity of the cryoprotectant used?

Another question relates more to my ignorance about cryo-perfusion and
is a general point.  Glycerol, with its high molecular weight, I
understand, permeates tissues more slowly than water so that in rapidly
perfusing a patient/animal with glycerol there is a period during which
the glycerol osmotically extracts (some of) the water from the tissues,
before the glycerol is able to replace the missing water.  The effect
is that the tissues first shrink though dehydration, later swelling as
the glycerol moves into the tissues from the blood-stream.  Is this
correct and is there some way around this?  Could Robert comment on the
whether the Ukraine experiments observed this or how they circumvented
the problem?  If indeed it is a problem.

Michael Price                        

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