X-Message-Number: 6920
From: Brian Wowk <>
Date: Tue, 17 Sep 1996 01:31:46 -0500
Subject: Technical stuff

Bob Ettinger writes:

>2. Brian Wowk says cooling rate may be critical, and faster cooling generally
>results in less damage, hence the rapid cooling of Mrs. Visser's rat hearts
>may mean her method is not applicable to larger organs, which will
>necessarily experience slower cooling.

>(a) As I said, the fact that thawing was much slower than cooling (thawing
>takes roughly 50 times as long as cooling) lends support to the idea that
>slower cooling would also have worked. This is obvious for reasons too
>numerous to mention. If you want references, see e.g. Meryman's CRYOBIOLOGY
>(1966), p. 70: "Wherever rapid freezing is necessary for survival, rapid
>thawing also is almost universally necessary."

	This assumes you are on the far side of the survival vs. cooling
rate curve, where extensive intracellular freezing is occuring (which
you are not).  For the side of the curve where survival is still
improving with cooling rate, consider the words of Mazur (1984)

	But when cells are cooled more slowly than optimum, the
	response is reversed-- survival is considerably higher
	with slow warming than with rapid.  

Fig. 18 in the Mazur paper I referenced yesterday makes this point
strikingly.  
 

> my impression was
> that PP looks to vitrification in a method that DOES use glycerol. Maybe
> the "by itself" qualification means it will be different with vitrification.

	Current vitrification solutions are a mixture of four different
agents, none of which is glycerol.  The flexibility to "mix and match"
agents in this manner creates the large "design space" that drives the
optimism the method will be adaptable to other organs.  It gives room
to maneuver around difficult problems such as toxicity-- an issue
that could rapidly become a show-stopper for an approach that depends
on a single agent.  

	As to PP looking to exclusively to vitrification, obviously
that will change if the Visser method is demonstrated to work at slow
cooling rates.  The main idea of PP (to me) is to get a coordinated
large-scale and, above all, professional effort going that will do
WHATEVER IT TAKES to perfect brain preservation. 

>4. Brian minimizes the importance of the rat heart success by saying it is
>[merely] "...an extension of similar work peviously reported for small
>amphibians to small mammals..."

> Karow and others have tried for about 30 years to accomplish this feat.

	Freezing small animal organs by dunking them directly in liquid
nitrogen?  I didn't know anyone but Luyet and Rapatz had a fascination
for these of experiments.  Certainly no organ cryopreservation
lab today screens candidate agents in this manner.  The results would
be meaningless because of the cooling rate issue. 

> If your vitrification had accomplished this, you would be trumpeting it,
> with justification.

	Nonsense.  Again, *the results would be meaningless because of the
cooling rate issue*.   

> You have already trumpeted that your secret version of
> vitrification has been successful with SLICES of rabbit kidneys.

	At cooling rates compatible with large organ preservation.
sci.cryonics is also a considerably smaller trumpet than the
international news media.

> Is success with slices of rabbit kidneys more impressive than success
> with whole rat hearts?

	Not to journalists, of course.  But I *do* find small samples
recovered after slow cooling more impressive than whole small organs
recovered under cooling conditions that could never be applied to
large organs.  Not to say that there isn't more to the Visser method
than meets the eye (Bob hints there is).  We all just may have to
live with the fact that the enthusiasm Bob feels will not be contagious
until a successful slow cooling experiment is produced. 

> If I wanted to do some of my own spin doctoring, I could remind PP people
> that, even if whole rabbit kidneys are finally revived after vitrification
> (after many years of trying), using RF heating, it is FAR from clear that
> this methodology can be extended to larger organs. The problems with RF
> heating become MUCH greater with larger specimens. 

	Problems would become greater with microwave heating, not RF
heating.  I irradiate large organs (human brains) with 127 MHz everyday,
and the penetration is very uniform.  If you can supply the power,
RF will heat large organs just fine. 

> FOCUS: Various arm-chair experts want to see more and more details...

	Perhaps we've all done enough arm-chair cryobiology, and it's
time to turn this question over to experts as I suggest in another
message.

***************************************************************************
Brian Wowk          CryoCare Foundation               1-800-TOP-CARE
President           Human Cryopreservation Services   
   http://www.cryocare.org/cryocare/

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