X-Message-Number: 1787
Date: 21 Feb 93 19:03:57 EST
From: Mike Darwin <>
Subject: CRYONICS Letter to Ettinger re -136 C Proposal
From: Mike Darwin
To: CRYONET
20 February, 1993
The following letter has been sent to Bob Ettinger:
Cryovita Laboratories
1220 E. Washinton St. #24
Colton, CA 92324
19 February, 1993
Robert Ettinger
Cryonics Institute
2443 Roanoke
Oak Park, MI 48237
Dear Bob,
Saul Kent was kind enough to pass me a copy of your letter of 12
February. I am prompted to write a response for several reasons which I
shall detail directly.
First, our work here, and the work of Greg Fahy work at the Red Cross,
has disclosed a troubling wrinkle to the cracking problem. It seems that
the larger the mass of bulk solution tested, the closer fracturing occurs
to the glass transition point (herein abbreviated TG). I have tried
cooling some bulk 1-liter 60% (v/v) glycerol water solution and have found
fracturing to occur at -120*C. The problem with my experiment is that I
could not control the rate of cooling or be assured of its homogeneity.
However, Greg has reported similar results in his bulk solution runs. He
would definitely be the best person to brief you on his work, and it is my
hope that he has already done so.
The point is that we may have to store very close to, or right at TG
and this raises troubling questions about biological stability over long
periods of time. For example, I believe that TG for the water-glycerol-
starch solution we were using was about -110*C.
The second reason for writing is to share my thoughts and tell you
what is already in progress out here. We have given a great deal of
thought to this problem as you might imagine since we first discovered it
nearly a decade ago. Your approach is a very clever one and in some ways
parallels ideas tossed around out here. Let me first comment on your idea
and then tell you a little about some others.
I think your idea a very workable one from a technical standpoint,
but it presents some very tough logistic problems. Obviously, you can
only get one layer of patients in the storage unit. This isn't very
economical and space costs a great deal of money, particularly in areas
such as California. Otherwise it is an excellent idea!
Now I would like to tell you what has been proposed out here and give
you some specifics about what is happening vis a vis Cryovita and
Biopreservation.
There are several alternative approaches to this problem which would
also use liquid nitrogen but which are a bit more complicated than yours
(and thus a little less safe):
1) If storage at -120*C or 130*C is pursued it should be possible to
get rid of the need for high (and perhaps even for soft) vacuum equipment
and go to foam. Certainly the -135*C mechanical freezers use this
approach, and if the structure were large enough, it should be economical.
What I envisioned was a room sized storage module with patients racked in
cocoons or pods as you describe. The liquid nitrogen holding dewar would
be in the room with the patients and would discharge LN2 under control of
a thermostat. The pods or cocoons would damp temperature variations and
the air would be vigorously stirred with fans. The patients in the pods
could be surrounded with a eutectic material which will melt at an
appropriate temperature.
We are in the process of applying for a patent on such a system using
ethyl chloride as the eutectic material (and we have identified others
that may be useful for different holding temperatures). Such a system
could accommodate a large number of patients, should be reasonably
economical to operate, and would be reasonably safe. Also, the power
requirements for fans and thermostats are minimal compared to
refrigerators and whats more, they are cheap enough that they can be
backed-up heavily at little added cost. This is in sharp contrast to -
135*C refrigeration equipment which is very inefficient, complicated,
unreliable, and incredibly costly.
2) An alternative approach would use a similar fan-stirred system but
with LN2 being constantly fed into the system under some kind of passive
scheme. The system could also be heavily backed up against power failure
of all kinds (including failure of the emergency generator) by using LN2
to drive compressed air motors powering back-up stirring fans.
We are in the process of creating a new company which will be
pursuing this kind of work as well as basic studies in brain
cryopreservation and aging. Mark Connaughton, a former Rockwell Shuttle
engineer (Jerry Leaf's brother-in-law) is current preparing a proposal for
this part of the project. I have not spoken with Mark about this, but I
believe he would welcome wider participation with this project -- and we
do have a limited amount of space we can give to it.
While it would be premature to describe everything that is going on
here, I will enclose a few photos which show what our facilities are like,
and include a brief description of the research hardware available. I do
this not only to give you an overview of what we are doing, but also
because we are trying very hard to undertake basic research to perfect
brain cryopreservation, and I believe we are very well equipped to do it.
Sincerely,
Mike Darwin
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