X-Message-Number: 6595
Date: 24 Jul 96 04:30:12 EDT
From: Paul Wakfer <>
Subject: Prometheus: Reply to Keith Lynch
First, I want to very warmly thank Keith for stating why he hasn't made
a pledge yet, because I know that he certainly supports the idea of this
project and has already done a lot of Internet work on its behalf. It would
be perfectly valid to answer by simply saying: "just pledge anyway, as if you
are satisfied with the answers to your questions, and when these questions
*are* later answered, which they *must* be before you have to start any
payments on your pledge, you may withdraw or modify your pledge relative to
your evaluation of the answers". Yet, I am aware of two things wrong with
such an answer to Keith. The first is that the reasonable ethics of many
people will not allow them to make a pledge until they are really sure that
they can honor it. The second is that how *much* of your life you are willing
to put into saving it, by means of this project, clearly depends on the
strength of the methods of accomplishing the project's goal, and exactly this
is the essence of Keith's questions.
Now it just so happens that I have been anticipating such questions and have
obtained answers from our scientific advisors which I have edited and posted
separately. (See posting: Prometheus Project: Scientific Method)
Keith wrote:
>This is the main reason I haven't made any pledge yet.
>
>* How do you cool a brain embedded in a warm body? Sure you can use
> perfusion, but only until the perfusate becomes too cold and viscous
> to flow.
In the in-situ model, the brain will only be cooled to -70xC, and cold
perfluorochemical which is not too viscous until well below that temperature
will be used as the cooling perfusate base. Before doing any of this you
isolate the brain vasculature from the rest of the head, and the head
vasculature from the rest of the body. (They are not severed, just clamped to
enable their separate perfusion.)
>* How do you keep the vitrified brain cold when it's embedded in a
> warm body?
By isolation of vasculature and maintaining a temperature gradient to the
tissues external to the brain.
>* How do you keep the parts of the body adjacent to the vitrified
> brain from freezing?
Some of them *will* freeze to different degrees, but our method of isolation
and perfusion they will be designed to give them cryoprotectant strength
sufficient to prevent damage.
>* How do you rapidly rewarm the brain without roasting the rest of
> the animal?
In the in-situ model, we don't go below Tg so little devitrification can take
place during rewarming. Besides warm perfluorochemical perfusion should allow
quite rapid rewarming.
>I will make a pledge when I get a believable answer to each of these
>questions.
Then I hope to hear from you soon :)
>Or when I hear of some plausible method of testing viability
>which doesn't involve a vitrified brain in a warm body.
Neurobiological testing of a brain perfused, removed, cooled to -140xC,
rewarmed (rapid here), and either transplanted vascularly to a living animal
and tested in vivo, or connected to a heart-lung machine and tested in vitro
will also be done. How this testing will be done to be "plausible", has not
been worked out yet. Neuroscience members of this forum are invited to
comment here.
-- Paul --
!!!!! REVERSIBLE BRAIN CRYOPRESERVATION *CAN* BE ACHIEVED IN 10 YEARS !!!!!
Paul Wakfer email: Voice/Fax: Pager:
US: 1220 E Washington St #24, Colton, CA 92324 909-481-4433 800-805-2870
Canada: 238 Davenport Rd #240, Toronto, ON M5R 1J6 416-968-6291 416-446-9461
(in Canada until July 28)
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