X-Message-Number: 7749
From: Brian Wowk <>
Date: Mon, 24 Feb 1997 20:15:33 -0600 (CST)
Subject: More Questions

Thomas Donaldson asks on CryoNet:


>After sending my last questions about fluorocarbon cooling, I thought of 
another
>one: presumably this process also involves infusion of a cryoprotectant (CP). 
>Ignoring just which CP this may be (possibly an important question), is the
>CP also dissolved in the fluorocarbon solution? If it is not, then do you 
>get a problem with its REMOVAL as you circulate the solution? And if you do
>get such a problem, it may or may not be serious (perhaps --- speculating:
>once the temperature is low enough and you have the fluorocarbon in the 
>brain, the CP is no longer necessary).

	Fluorocarbons are very peculiar compounds.  They are
immiscible (unmixable) with either water or lipids.  Chemists
sometimes call fluorocarbons the "third phase" of chemistry.
The combination of both hydrophobia and lipophobia is what
makes fluorocarbons so non-toxic; they are inherently unable
to interact with living matter.

	The procedure is to perfuse with conventional
cryoprotectants in a normal carrier solution until a target
sub-zero temperature is reached, flush out the water-based
perfusate with fluorocarbon, and continue cooling with pure
fluorocarbon.  The switch between aqueous perfusate and
immisicible fluorocarbon (and visa versa) is one of the 
most difficult parts of the procedure.  The tricks we have
developed for doing this are proprietary.

	There is of course no problem losing CPA to the
fluorocarbon during cooling or rewarming.  CPAs are water
soluble, with negligible solubility in fluorocarbon.   
	
 
 writes:

>Fluorocarbon has been developed as a blood substitute quiete a
>while ago.

	Fluorocarbon blood substitutes are emmulsions.  We are
using pure fluorocarbon. 


>what is the equilibrium contant (K) between the 
>cytoplasm and FCB.

	The compound we are using remains confined to vessels;
it is not soluble in water, and does not enter cells.


 re Cryo Journal Club 3 also writes:

>One can conclude from this experiment that cells have to be healthy in
>order to survive freezing. It is well known that cells that do not adhere
>well to culture plates or flasks are unhealthy. The implication for cryonics
>is that suspension should be concentrated on a group of cells such as in
>the brain in order to maximize revival.

	One might also conclude that minimizing ischemic injury
is important to minimize cryoinjury. 


 (Mike Coward) writes:

>How many services offer suspension and reanimation.

	None.  Read the cryonics FAQ at
http://www.cryonet.org/~kqb/cryonet.html 


Peter Merel asks:

>A general question to the orgs then: what do you intend to do
>with cloning technology now that it is available to you?

	In pratical terms it's NOT yet available, but when it
is, the logical course of action would be to seriously consider
cloning those patients who were cryopreserved with little or
no brain structure (and whose funding would not be so depleted
that more advanced methods could not later be tried).

	Rather ironic that contrary to conventional cryonics
wisdom, it might be the WORST injured patients who come back
first!

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

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=7749