X-Message-Number: 3557
Subject: SCI.CRYONICS: Low Temperature Cryonics
From:  (Ben Best)
Date: Sat, 31 Dec 1994 09:52:00 -0500


   I briefly mentioned an interest in liquid Helium storage several
weeks ago and was quickly attacked by someone who showed little
interest in hearing me out. Sometimes I wonder if there are not
"fundamentalist cryonicists" who are as intolerant of deviant ideas as
fundamentalist religionists -- and for the same reasons.  Anyway, the
time has come for me to explain my reasoning, beginning with a brief
review of the "state of the art" of cryonic cryopreservation.

   In the 1950s Audrey Smith demonstrated that hamsters could be frozen
to nearly -1 Celcius such that 60% of brain water is turned to
crystalline ice -- with no loss of normal behavior upon rewarming. It is
also known that 27.2% glycerol (3.72 Molar) in water results in no more
than 60% of the water being frozen -- the rest is vitrified solid
(i.e. a solid which has hardened like glass rather than formed ice
crystals). To avoid the toxicity, viscosity and dehydration of higher
glycerol concentrations, cryonic suspensions were performed fulfilling
the "Smith Criterion" figure of 3.72 Molar glycerol. Light microscopy
seemed to indicate that 3.72 Molar glycerol might not be causing
freezing damage. Then 3 Trans Time whole-body patients were moved to
Alcor and converted to neuro. Autopsy of the bodies indicated that
large-scale cracking might be a problem, even if ice-crystal damage
is not.

   Glass turns from a liquid to a solid by gradual increase in viscosity
-- in distinction to the abrupt phase transition seen with
crystal-formation. Nonetheless, the increase in viscosity is not
completely uniform with temperature-drop. In particular, there tends to
be a "glass transition temperature" at which solidification proceeds
more rapidly for small temperature-change. For glycerol/water solutions
this tends to be in the -90 to -130 degree Celcius range. When glasses
are cooled, cooling proceeds from outside to inside, resulting in
stresses from the warmer core which needs to contract more than the
surface. Robert Ettinger has asserted that very slow cooling below glass
transition temperature eliminates the cracking problem -- and the
Cryonics Institute has contracted Ukrainian scientists to prove this
point. Brian Wowk has investigated the feasibility of "cold room"
storage just below glass transition (-130 Celcius) and has demonstrated
that this could be considerably more economical than liquid nitrogen.

    All this concern with cracking made a great deal of sense when we
believed (on the basis of light microscopy) that there is no freezing
damage. If suspended animation of the brain were demonstrably achieved,
I would be very interested in storage at -130 Celcius. But in the
December 1991 issue of CRYONICS magazine, cryobiologist Dr. Greg Fahy
wrote of the results of his ultramicroscopy examination of a rabbit
brain frozen to -130 Celcius. He observed considerable freezing damage.
The "Smith Criterion" has been abandoned by many cryonicists, and
Alcor/Biopreservation patients are now being frozen with glycerol
concentrations above 7 Molar. Unfortunately, perfusion of glycerol into
cells is poor and considerable dehydration is occurring. With known
freezing damage, extensive protein cross-linking due to dehydration, and
cryoprotectant toxicity at the cellular level -- gross cracking is the
least of our worries. Even without cracking, we are very dependent on
future molecular repair technology for current cryonics patients. This
picture could be very different if the vitrification solution that
Dr. Fahy has used with kidneys proves to be a workable alternative to
glycerol.

   In Hugh Hixon's classic essay "How Cold is Cold Enough" he says
"... any temperature below -130 C to -135 C is probably safe due to
elimination of translational molecular movement as a result of
vitrification". Yet at the November 1994 Cryonics Conference Hugh
indicated an interest in temperatures *above* glass transition as a
means of avoiding the "brittleness" of glass. I think Hugh has made
mistakes on both sides of the "glass transition" coin.

    What are the effects of freezing? Tissue is crushed, mangled and
small pieces are broken-off. Yet this does not necessarily mean the kind
of loss of structure that happens when a piece of tissue is dissolved in
a bowl of acid. The crushing, mangling and breaking-off of small pieces
are the result of deterministic vector forces. Some future computational
and molecular-repair technology may well be able to deduce original
structure on the basis of the evidence -- as long as the evidence is
maintained. The worst thing that can happen is the "dissolution" of
structure and small pieces. I believe Hugh's claim that translational
motion does not exist below glass transition is mistaken. Molecules in
an ice crystal may have vibrational rather than translational motion,
but there is no reason for this to be true of a vitrified solid. Try
looking at a window pane that is decades old -- the slow flow has
visible effects. Above glass transition temperature the situation is
worse -- risking dissolution of structure to avoid brittleness and
cracking would be disastrous, in my mind. The very most conservative
approach is the lowest possible temperature.

   Only 3 elements have boiling points below that of liquid nitrogen
(which boils at 77 degrees Kelvin) -- namely Neon (27 Kelvin),
Hydrogen (20 Kelvin) and Helium (4.2 Kelvin). Current dewars could not
used Helium because it diffuses through steel and destroys the vacuum --
protective linings would have to be added. Neon is probably safer to use
than Hydrogen, and is more plentiful than Helium. But all are probably
at least an order of magnitude more expensive than liquid nitrogen.
Liquid nitrogen is the best low temperature storage I can afford, but a
lower temperature might not be a bad idea for a very wealthy person. It
is difficult to do a cost/benefit analysis on this problem when there
are so many questions concerning WHAT needs to be preserved. That is the
motive behind my series "The Anatomical Basis of Mind" in CANADIAN
CRYONICS NEWS.

    I believe it is important to consider the consequences of all
biostasis options, whether or not they prove to be feasible. What seems
impractical today may become very practical tomorrow -- or, at least,
inspire ideas which are more practical.  Also, I don't want anyone to
think that criticism of a sentence in Hugh Hixon's essay means that
I don't respect the man or his work. I respect the man and I think the
essay deserves to be respected as a classic piece of analysis.

                 -- Ben Best ()

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