X-Message-Number: 3074
Date: 07 Sep 94 01:28:06 EDT
From: Mike Darwin <>
Subject: SCI.CRYONICS frozen-thawed brains

Thomas Donaldson remarks:

>>In THE IMMORTALIST... you will be able to read of
>>an experiment on sheeps brains, freezing without cryoprotectant, down to LN
>>temperatures. This caused a lot of destruction, and the cells clearly could
>>not revive on their own. They would need a lot of help and reengineering. AT
>>THE SAME TIME, for cryonics the results were a bit hopeful because close
>>scrutiny could show enough survival so that methods can be imagined which 
>>might do that repair.

Thomas, do you know something I don't?  The micrographs which CI has published
were only of brains subjected to glycerol perfusion and then fixation.  I have
seen no micrographs of straight frozen brains published by CI.  The ones we've
done here would hardly inspire the remarks:

>>the results were a bit hopeful because close
>>scrutiny could show enough survival so that methods can be imagined which 
>>might do that repair.

Thomas further states:

>>Biopreservation will hire people who are not 
>>cryonicists. They basically suspend people for a prearranged payment, and
>>transfer them afterwards to some other organization for permanent storage.

As far as it goes this statement is true.  However, I would like to note the
following:

1) BPI asnd 21st are engaged in research.  21st is engaged exclusively in
conventional biomedical R&D and has no cryonics connection.  It is also
important to point out that BPI is a service provider.  We do carry out
cryoprotective perfusion and cooling to dry ice, but technically we do not
"suspend people." That is the cryonics organization's job.  We only subcontract
(i.e., make our services available) to cryonics organizations.


2) People we hire are being hired primarily for research and in fact willingness
to participate in human cryopreservations is a minor consideration; the people
we need will have their hands full just dealing with the animal research end of
the program here.

3)  It is not only true that we will hire noncryonicists, but we in fact have a
policy of discrimination against cryonicists in that we have enough of them
already and that's probably too many!  While we are not as dogmatic as the
Society for Cryobiology in our rejection of those who are card carrying
cryonicists, it IS  material strike against an applicant.  Of course, stellar
qualifications would more than compensate for the undesirability of being a
cryonicist.


Thomas' comments about freeze-tolerant, overwintering vertebrates (trurtles,
frogs, etc.) are good ones.  These animals carefully control where they allow

ice to form and, much like Smith's hamsters, they limit the amount of body water

they allow to be converted into ice to roughly 60% (v/v), although I believe the
tree frogs may be an exception to this.

The point is that the ultra-low temperatures to which we are forced to cool
human cryopreservation patients are a whole other ball game.  However, it is
also true that our overwintering vertebrate cousins may have some lessons to

teach us.  One of the consistent lesions I see in cryopreserved mammalian brains
(cats treated with 4M glycerol) is the presence of large, pericapillary ice
holes.  In the frozen state (using freeze-substitution) you can see the ice
masses present as white spaces.  Upon thawing, you see a large, debris-strewn
cavity.  I'll bet you our tree frog friends don't develop these pericapillary
ice masses with attendant tears in the neuropil.

I wonder if Ken Storey or others have done freeze-substitution studies on these
animals at -5xC or -10xC -- temperatures which I believe they overwinter at?

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