X-Message-Number: 3371
Subject: SCI.CRYONICS: High Pressure Cryonics Reanimated
From:  (Ben Best)
Date: Mon, 31 Oct 1994 04:04:00 -0500

    I was even more disappointed than Ken Stone that the idea of High
Pressure Cryonics evoked no discussion -- or even a display of
comprehension. In conversation, Paul Wakfer told me that he and Mike
Darwin simply dismissed the idea as "impractical". I am reminded of the
adage that "a person with a hammer tends to view every problem as a
nail" -- and I would add the comment that the person also tends to
dismiss problems requiring a screwdriver as "impractical".

    To be "practical" for cryonics, high pressure would first have to be
shown to be of benefit and second would have to be shown to be feasible
to incorporate into cryopreservation procedures with manageable
equipment at manageable costs.

    I am disappointed that despite his interest Ken Stone takes it to be
self-evident that "quick changes in pressure would smush the patient". I
wrote at length replying to this misconception and I am not inclined to
repeat myself.

    There are two high pressure phenomena which are of potential benefit
to cryonics. The first phenomenon is that High Pressure (2,000
atmospheres) depresses the freezing point of water to -22 degrees
Celcius. The second phenomenon is that Very High Pressure (14,000
atmospheres) elevates the freezing point of water to +50 degrees
Celcius. The effect of High Pressure is well-known in the cryobiological
community, but has only been dabbled-with. The effect of Very High
Pressure has not been discussed before in connection with cryobiology
before, to my knowledge. I was hopeful of raising consciousness on Very
High Pressure, but I would love to see more work on both High Pressure
and Very High Pressure.

    Thanks to work by Ukrainian researchers, Robert Ettinger now feels
confident that cracking is not a problem for liquid nitrogen cryostasis.
Even if this is true, there remains the larger problems of freezing
damage and loss of viability. I believe that immediate use of High
Pressure would virtually guarantee reduction of freezing damage and
increased viability. Unfortunately, the concept of *reduced freezing
damage* and of *increased viability* seem alien to cryonics research.
Viability and (even moreso) freezing damage are viewed as
all-or-nothing. Greater use of electromicroscopy in connection with
cryopreservation procedures will hopefully result in more appreciation
of the distinctions between greater and lesser freezing damage.

    Cryoprotectant toxicity is reduced at lower temperature. Therefore,
the use of High Pressure to maintain a liquid state at -20 degrees
Celcius and below could mean introducing cryoprotectant at temperatures
at which their toxicity is minimal. This could be of particular benefit
for DMSO since it is far less toxic at low temperature and it perfuses
cells so much better than glycerol.

    Freezing damage is not so much due to "puncturing of cells by ice
crystals" as due to mechanical crushing resulting from the fact that ice
is less dense than water. Very High Pressure could eliminate volume
expansion if pressure can be applied so *rapidly* that ice crystal
formation is prevented. Phase transition to a solid state produced by
cooling depends upon conduction -- which means that it is necessarily
so slow as to allow ice crystal formation. Phase transition produced
by *rapid* application of Very High Pressure has the potential for
producing vitrification by not allowing time for ice crystals (low
density) to form. Such a procedure could conceivably be done without
cryoprotectant -- and thus without cryoprotectant toxicity.

    I don't think that mechanical damage ("smushing" cells) is the
crucial problem with Very High Pressure Cryonics. I believe the key
problems needing investigation are heat-of-fusion and developing
manageable equipment at a reasonable cost. And, of course, arousing
the interest of people who have resources needed to investigate
these questions.

                     -- Ben Best ()

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