X-Message-Number: 1485
From:	Ben Best <>
Date:	Mon, 21 Dec 1992 19:00:00 -0500
Subject: more on cryoprotectants


ERRATA AGAIN: Garret Smyth is correct, I meant "emulsion", not
              "suspension". (Double-entendres cloud the mind.)

     Canada Remote Systems, my network host, periodically delays
my USENET messages several days and then sends them to me in a
batch -- which slows down my response time. (This is an excuse, not
an apology.) In any case, my CRYONET dialogue about cryopreservation
seems to be winding-down. I need to study the literature more and
formulate my thoughts before doing any more mouthing-off -- and I will
attempt to crystallize this effort in an article in the Winter issue
of CANADIAN CRYONICS NEWS. But a few parting thoughts:

    REPLY TO MIKE DARWIN

     I am not suggesting that theorizing is a substitute for research,
but it can help research to ask the right questions. Thank you for your
comments about dehydration damage as opposed to freezing damage, but
since we don't know what structures are the most essential to preserve,
can we really be sure that 6M glycerol is better than 4M? In Greg Fahy's
December 1991 CRYONICS article he comments that 6M glycerol "has
produced either superb preservation or preservation marred by massive
cellular dehydration, depending on the glycerolization technique." What
technique avoids dehydration? I have been fantasizing about using a
chemical to accompany glycerol which would cause non-destructive
puncturing of cell membranes -- thereby allowing easy perfusion.

   I can't comment on Suda's data, since I haven't seen it. But if
Greg is in possession of it, why can't you (or I) get a copy?

   Greg's vitrification solution of DMSO, propylene glycol and
formamide sounds more appealing than DMSO alone, but I'm still
wondering why he excluded glycerol. If my theory of high perfusion with
low molecular weight is correct, formamide (HCONH2) with a molecular
weight of 45 would be excellent. Greg sounds so awesomely confident in
CRYOMSG 486 when he says "I may or may not be able to work out a
technique for vitrifying the brain, but I can certainly reduce ice
crystal growth enough to preclude structural damage, which would be
good enough." If he is right, why isn't implementing his techniques
the NUMBER ONE priority of cryonics research? Did he make his statement
before discovering that his DMSO-propylene glycol-formamide mixture only
vitrified the grey matter of dog's brains, and not the white matter? It
sounds to me as if what is needed the most is a low molecular weight
lipophilic cryoprotectant that can be added to Greg's mixture to
protect the white matter.

                    -- Ben Best (ben.best%)
--
Canada Remote Systems  - Toronto, Ontario
World's Largest PCBOARD System - 416-629-7000/629-7044

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