X-Message-Number: 16556
Date: Sat, 16 Jun 2001 13:47:27 -0400 (EDT)
From: Ben Best <>
Subject: CI Protocols

On Sat, 16 Jun 2001, Olaf Henry wrote:

> >I think if CI had been more receptive to conventional cryobiology
> >research, it might have chosen to start ramping perfusion concentration
> >in 1991 rather than in 2001, just to take one obvious example.
>
> Drum roll... Charles announces the importance of ramping for the
> twenty-twelfth time here on Cryonet.  The results of CI's
> research as posted here repeatedly show very little difference.

    I agree that under the conditions in which CI performs 
cryopreparation that it probably makes (at best) a small difference
whether ramping is used or not. And I base this conclusion not 
on CI's experiments, but on my review of cryobiology literature
which I describe (with the references) in my essay "Ramping of
Cryoprotectant in Closed-Circuit Perfusion", which can be found
on my website at:

    http://www.benbest.com/cryonics/protocol.html

   On the other hand, it makes little sense for CI to do anything other
than cool as rapidly as possible to -100oC or lower (-130oC -- Tg for 
pure cryoprotectant). Only below these temperatures is there any chance
of cracking. One might make the argument that such rapid cooling above
that temperature range could increase the chewing-up of tissues. Even
if that were true (and it is only a wild speculation) such damage could
not be worse than the dissolution of structure by hydrolysis -- which 
increases as long as there is any fluid (calcium chloride salts have
a eutectic temperature of around -55oC -- off the top of my head). Future
molecular repair technology may have some chance against freezing 
damage, but would have little chance of recovering dissolved structure
from "soup".

   I take this as grounds not for beating CI over the head, but for 
strongly encouraging them to change this feature of their protocols as
soon as possible (I am a CI member). Other changes in their protocols
could involve costly equipment and trained staff. This change would be
much simpler to implement. I hope that soon after Dr. Pichugin arrives 
at CI in July, attention will be directed to making this change in the
protocols. 
                                  -- Ben Best

         --------------------------------------------
            Ben Best ()
            http://www.benbest.com/

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=16556