X-Message-Number: 7752
From: Brian Wowk <>
Date: Mon, 24 Feb 1997 23:19:03 -0600 (CST)
Subject: Reply to Bob Ettinger

Bob Ettinger writes:

>What I said was, first, that expansion of water on freezing is only around
>10%, and therefore...

	The expansion of water on freezing is irrelevant.  The cause
of cryoinjury during freezing is the progressive conversion of water
to ice; a damage mechanism that would be equally severe even if
water froze with no change in volume.  

>it is not true, as you said (#7715) that "Even the fabric
>of cells themselves is crushed into these tiny spaces among the ice
>crystals." Your statement carried a clear intimation that most of the space
>is occupied by ice crystals, leaving only tiny spaces for tissue, AND an
>intimation that essentially all of the water will end up in these ice
>crystals. This is not the case.

	When tissue is frozen with no cryoprotectant (which happens  
alarmingly often in cryonics), 96% of tissue water is converted to
ice.  This represents at least 80% of the tissue volume, with
cell structures *crushed* into the remainly 20% volume.  You can
find these numbers (with vivid micrographs showing frozen cells
being crushed into these stated volumes) in

	"Freezing of living cells: mechanisms and implications"
	by Peter Mazur, American Journal of Physiology 247
	(Cell Physiology 16): C125-C142, 1984.

Of course cryoprotectants reduce the percentage of water that is
converted to ice, but this was explained in my article.  With
non-vitrifiable concentrations of cryoprotectant, the same mechanisms
of freezing injury are still operative, even if of lower magnitude. 

>As you correctly say, we needn't depend on theory for everything; a lot of
>experimental evidence is available. And electron and light micrographs of
>specimens prepared in many different ways, while showing a lot of damage,
>also show a lot of retention of structure.

	Agree (at least for freezing with good cryoprotection).  

>I am struck by a couple of things you say in #7731--that "with a
>hyperadvanced nanotechnology, even patients frozen under very bad conditions
>could be revived....[but]...freezing, as it occurs in cryonics today, is a
>very serious injury that will require advanced nanotechnology for repair."
>This is just a rephrasing of my long-standing conjecture (although you
>elevate it above conjecture!) that full-fledged nanotech may be both
>necessary and sufficient to revive patients frozen by any method heretofore
>used. Interesting, and with doubtless unintended implications.

	I have held this position since my earliest involvement in
cryonics, and you will find it in writing in the first editions of
Cryonics: Reaching for Tomorrow, written almost 10 years ago.
If you have sophisticated control over the analysis and synthesis
of biological material, then eventually ANYBODY with a trace of
biological structure will be able to be revived.

	The crucial issue is what is meant by "revived".  A lot of
people are going to come back as amnesiac clones.  The question of
cryonics is therefore not whether people can be revived, but *how
much memory* they are going to be revived with?  So whenever I
express scepticism about whether cryonics as practiced today will
work, you can take that mean allowing revival with memory and
identity intact.  It's still far from obvious that this is certain.

Brian Wowk          CryoCare Foundation               1-800-TOP-CARE
President           Human Cryopreservation Services   

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