X-Message-Number: 16556 Date: Sat, 16 Jun 2001 13:47:27 -0400 (EDT) From: Ben Best <> Subject: CI Protocols On Sat, 16 Jun 2001, Olaf Henry wrote: > >I think if CI had been more receptive to conventional cryobiology > >research, it might have chosen to start ramping perfusion concentration > >in 1991 rather than in 2001, just to take one obvious example. > > Drum roll... Charles announces the importance of ramping for the > twenty-twelfth time here on Cryonet. The results of CI's > research as posted here repeatedly show very little difference. I agree that under the conditions in which CI performs cryopreparation that it probably makes (at best) a small difference whether ramping is used or not. And I base this conclusion not on CI's experiments, but on my review of cryobiology literature which I describe (with the references) in my essay "Ramping of Cryoprotectant in Closed-Circuit Perfusion", which can be found on my website at: http://www.benbest.com/cryonics/protocol.html On the other hand, it makes little sense for CI to do anything other than cool as rapidly as possible to -100oC or lower (-130oC -- Tg for pure cryoprotectant). Only below these temperatures is there any chance of cracking. One might make the argument that such rapid cooling above that temperature range could increase the chewing-up of tissues. Even if that were true (and it is only a wild speculation) such damage could not be worse than the dissolution of structure by hydrolysis -- which increases as long as there is any fluid (calcium chloride salts have a eutectic temperature of around -55oC -- off the top of my head). Future molecular repair technology may have some chance against freezing damage, but would have little chance of recovering dissolved structure from "soup". I take this as grounds not for beating CI over the head, but for strongly encouraging them to change this feature of their protocols as soon as possible (I am a CI member). Other changes in their protocols could involve costly equipment and trained staff. This change would be much simpler to implement. I hope that soon after Dr. Pichugin arrives at CI in July, attention will be directed to making this change in the protocols. -- Ben Best -------------------------------------------- Ben Best () http://www.benbest.com/ Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=16556