X-Message-Number: 6401
Date: Thu, 27 Jun 1996 12:56:35 -0400 (EDT)
From: Charles Platt <>
Subject: Freezing Injury

Hal Sternberg writes:

> In initial experiments we found animals could revive after being
> in a bath at -5 degrees C for 30 minutes. Then later we could
> revive hamsters after 30 min. at -10 degrees C, and soon after we
> could revive hamsters after being in a bath for 30 min. set at 
> -20 degrees C. These results have been encouraging.

So far so good, but this para doesn't say anything about the CONDITION of 
the animal.

> As mentioned previously, the most exciting and amazing finding of
> these experiments is that animals revive despite extensive freeze
> damage to the brain. There are specific lesions that appear as
> micro-hemorrhages (small red spots) that are only observed after
> freezing and never otherwise. These lesions are indicators that
> freezing has occurred. We have observed these lesions throughout
> the cortex and down through the diencephalon and brain stem in
> revived hamsters who were subsequently necropsied. Thus, it is
> clear that the nervous system can recover, to a certain extent,
> after massive and widespread freezing. 

What is meant by "recover to a certain extent"? Do specific brain areas
recover specific functions, or do you mean that the whole animal regains
some limited range of functions, like a stroke victim who can still blink
while being generally paralyzed? And if this is what you're talking 
about, shouldn't you describe specifically what you mean?

I notice no specific claims are made for the condition of the animals. Can
they move? Can they eat? Do they perceive objects? Can they run mazes? In
the absence of this data I have to suspect that the animals may not have
these capabilities and therefore the word "recover" is a relative concept.

Really this researh is impossible to evaluate until we know precisely what
kind of damage is being caused, and how it might be prevented. The
references to "red spots" are vague at best; are there electron
micrographs? Was simple white-light microscopy done? If so, where are the
results? Will they be published, as BioPreservation published its study of
brain preservation using new protocol in a previous issue of CryoCare
Report? Will the pictures be put on a web page somewhere? 

> There appears to be a high degree of tolerance to freezing of the
> mammalian nervous system (and perhaps other tissues) for short
> durations.

Tolerance in what sense? Do damaged areas resume their individual 
function, or is the brain's redundancy able to compensate for damage in a 
small area by distributing the functions elsewhere?

> hours, and longer). So perhaps formation of initial ice crystals
> may not be too destructive while ice crystallization/
> recrystallization with time appears to become increasingly
> destructive.

These statements are meaningless unless some numbers are attached, or some
other objective criterion is developed for evaluating the damage. 

I am disappointed by Dr. Sternberg's report because, taking this version
at face value, it gives ammunition to critics who have long complained
that cryonics research is not conducted on a professional basis. Of course
Dr. Sternberg may be presenting us only with a simplified, popularized
version of his work. If this is the case, I assure him there are people
here who would love to see a more serious description of the methods,
measurements, and results, and I do not believe that this would
necessarily infringe on any proprietary techniques involved. 

=============================== Charles Platt ==============================
                    vice-president / CryoCare Foundation
1-800-TOP-CARE        http://www.cryocare.org/cryocare        1-800-867-2273
============================================================================


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