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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=5465