X-Message-Number: 3986
From: Ralph Merkle <>
Subject: Re: Reversal of freezing injury
Date: Fri, 10 Mar 1995 13:14:55 PST

Thomas Donaldson said:

>To Ralph Merkle: For someone who believes that no work on better means of
>preservation is needed, you seem remarkably leery of the damage which present

*Sigh*.  I hope everyone realizes by now that Thomas is prone to attribute
statements, opinions, and beliefs to me that I do not hold, have never held,
and which I view as foolish.

>cracking may be quite sufficient to destroy those memories: nanotechnology

An interesting claim.  I must confess that fractures created at low temperature
are not high on my list of concerns. Freeze fracture methods are used today

as a method of providing high resolution imaging of tissue.  Hayat (in 
"Principles
and Techniques of Electron Microscopy: Biological Applications," Third edition,
by M. A. Hayat, CRC Press, 1989) says "Membranes split during freeze-fracturing

along their central hydrophobic plane, exposing intramembranous surfaces. ... 
The
fracture plane often follows the contours of membranes and leaves bumps or
depressions where it passes around vesicles and other cell organelles. ...
The fracturing process provides more accurate insight into the molecular
architecture of membranes than any other ultrastructural method."


It does not seem likely that this mechanism will result in significant 
information
loss.  Subsequent rewarming of fractured tissue to a liquid state would seem

likely to result in significant disruption.  It would seem desirable, therefore,
to avoid such rewarming.  The presence of fractures would make any method that

involved rewarming as a first step substantially less plausible than methods 
which
involve analysis while the tissue remains frozen.

Direct analysis and repair of frozen tissue would seem entirely feasible using
a medical technology based on a mature nanotechnology.  Those who view the
development of such a technology as either unlikely or problematic might
view fractures with grave concern.  Obviously, I am not a member of this group.

An effective method of demonstrating that cryonics works would be to freeze
a brain, thaw it, and demonstrate the retention of memory (and other behavioral

responses).  With today's technology, this implies that we must preserve 
function

in order to show that learned behavioral responses are present (we can't 
demonstrate

much of anything, today, with a non-functional brain).  Thus, an important 
objective

is to eliminate cracking damage in order to preserve function in order to 
demonstrate
retention of long term memory.


I (and many others!) would be very pleased by such a demonstration.  Further, 
such

a demonstration would be a major step in gaining acceptance in the medical 
community

(which, for reasons that are obscure to me, seems to require proof that cryonics

will work before supporting it's widespread use.  Requiring proof that a 
lifesaving

treatment will work prior to using it on a patient who will certainly die 
without

it is not consistent with the Hippocratic oath, evidently a point of such 
surpassing
subtlety that it eludes many people today).


The value of eliminating cracking for furthering this goal is entirely 
independent

of the likelihood that cracking results in information loss.  Eliminating 
cracking

would remain a valuable objective even if we had absolute proof that it resulted
in no significant information loss.



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