X-Message-Number: 5465
Date: Fri, 22 Dec 1995 23:33:10 -0800 (PST)
From: Doug Skrecky <>
Subject: Re: Permafrost and sorbitol

 In message 5461 J.C. wrote: 
 >How long would a patient last if properly perfused with sorbitol or
 >sucrose and then stored in a lead capsule or made from other metal in
 >permafrost. Most suspensions are straight and since the above can be
 >done at any funeral home it may be a more realistic option. 
 The short answers: (at least in theory)
       for sucrose: forever
      for sorbitol: a long long time
 There are however several caveats: 
 1. Unlike lotus seeds, all animals which can survive anhydrobiosis,
 require isolation from oxygen as well as moisture to retain viability. So
 a freeze-dried patient at a minimum would need to be stored with a
 dessicant and in an oxygen free atmosphere. The metal capsule would need
 to remain intact. This should not be a problem in the permafrost over
 timespans of interest. 
 2. Successful induction of anyhydrobiosis requires the presence of
 stabilizing disaccharides both inside as well as outside cells. 
 Unfortunately human cell membranes lack sucrose or trehalose
 transporters, so these sugars cannot at present be used to reliably
 stabilize freeze-dried cells, much less entire patients. 
 3. Unlike disaccharides, sorbitol can penetrate human cells so in theory
 successful freeze-drying could be accomplished now. Unlike sugars little
 research has been done on sorbitol since freeze-dried sorbitolized tissue
 cannot be stored at room temperature. The highest storage temperature
 that could be contemplated would be -9 C, which is the glass transition
 temperature (Tg) of completely dessicated sorbitol. Only the northern
 reaches of the arctic (eg: Resolute, N.W.T. Canada) would be suitible
 burial grounds for a sorbitol treated freeze-dried patient. Permafrost
 burial would not be cheap. 
    (I have recently visited the cemetary in Yellowknife, N.W.T. and
 talked to the gravedigger there. According to him temperatures below 0 C
 are to be found in October 8-10 feet in the ground. Ben Best has found
 that inexpensive burial is available in a colder local - Churchill,
 Manitoba. I have not yet visited this site, but I have read that
 permafrost temperatures are only slightly below 0 C even there.)
    For the present, inexpensive permafrost burial of a freeze-dried
 patient is not possible due to the limitations of sorbitol stability (-9
 C Tg) and surcose's lack of penetration of cell membranes. Further
 research in the next century should remove these limitations by either: 
 1. Testing various methods of permiabilizing cell membranes so
 disaccharides can penetrate, without inducing freezing damage to the
 cell. 
 2. Testing various carbohydrates with glass transitions higher than
 sorbitol, but which can still penetrate membranes. 
    I remain confident that freeze-drying will eventually superannuate
 cryonics, due to its vastly greatly safety margins in the long-term. I
 see freeze-drying as a natural evolution of current cryonic practices. At
 present based on the available research I have seen, the best
 possibilities for freeze-drying would involve sorbitol perfusion and
 storage in a cold room at less than -20 C.


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