X-Message-Number: 15119
Date: Sat, 16 Dec 2000 07:26:50 -0500 (EST)
From: Ben Best <>
Subject: Re: An assist to CPAs and Ice-Blockers (Erratum)

On Sat, 16 Dec 2000, Ben Best wrote:

>    CryoProtective Agents (CPAs) and Ice-Blockers can prevent
> ice-formation and promote vitrification. But Ice-Blockers
> typically do not cross cell membranes. And CPAs are always
> challenging to perfuse/diffuse because both their toxicity and
> viscosity vary inversely with temperature. 

    In my efforts at pompous simplicity, I misstated the 
facts. CPA viscosity does vary inversely with temperature 
-- so that the lower the temperature of introduction, the
more difficult it is to get the stuff to perfuse through
blood vessels and diffuse into cells. However, CPA toxicity
tends to vary DIRECTLY (not inversely) with temperature
-- meaning that it is much less toxic when introduced at
lower temperatures. Therein lies the trade-off: how to 
introduce the CPAs at a high enough temperature to 
minimize viscosity, but at a low enough temperature
to minimize toxicity. 

   Also, by the time genetic engineering is sophisticated
enough to modify genes so as to manufacture the "designer"
insulin-receptor of my fantasy, genetic engineering should
also be able to add genes for production of ice-blocker
proteins in the cells of mammals. If these proteins are
innocuous enough, they could be present at all times in
the cell without much harm. After all, if cells can 
function adequately with large amounts of lipofuscin, 
they should be able to tolerate some otherwise non-functional
ice-blocker proteins -- which don't need to be present in
high quantities to be effective. This is an advantage over
my proposed insulin receptor in that there is no time-critical
procedure to be applied in a cryonics emergency -- although
it is still time-critical that cooling occur rapidly after
deanimation. 
                                  -- Ben

         --------------------------------------------
            Ben Best ()
            http://www.benbest.com/
            ICQ -- http://www.mirabilis.com/20636141

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