X-Message-Number: 3812 Date: Tue, 07 Feb 1995 12:33:20 GMT From: (Michael Clive Price) Subject: Re: CryoNet #3787 - #3793 I have some questions for Robert Ettinger and others about the sheep head experiments that CI have been conducting, in particular about how their experimental procedures differ from Alcor's. Robert mentions that CI used a slower cool-down (a week to get down to dry-ice temperatures) and warm-up than usual and speculates that the apparent lack of cracking (to be confirmed shortly, it seems, on slides coming over from the Ukraine) may be due to this. In Robert's most interesting presentation, covering the past and looking to the future of cryonics, to the Sixth Annual Venturist Festival, reprinted in Alcor's _Cryonics_ (3rd quarter 1994) Robert also says that CI had previously experimented with using a different cryoperfusion technique - - namely loading in the glycerol-based cryoprotectant all in one go (if I may phrase it so) rather than slowly building up the concentration, which I believe is more conventional -- and that the Ukraine experiments were designed to replicate this particular feature as well. Since there was only mention of the slower cool-down and warm-up in Robert's latest report my first question is to ask whether the Ukraine sheep head experiments also used the "all in one go" approach to loading up the glycerol-based cryoprotectants. If so I wonder whether Robert could comment on the possibility that this may be the (putative) cause of the lack of cracking? (Admittedly the slow cool-down sounds the more likely cause, but I wonder if there is any evidence for this plausible explanation.) What was the molarity of the cryoprotectant used? Another question relates more to my ignorance about cryo-perfusion and is a general point. Glycerol, with its high molecular weight, I understand, permeates tissues more slowly than water so that in rapidly perfusing a patient/animal with glycerol there is a period during which the glycerol osmotically extracts (some of) the water from the tissues, before the glycerol is able to replace the missing water. The effect is that the tissues first shrink though dehydration, later swelling as the glycerol moves into the tissues from the blood-stream. Is this correct and is there some way around this? Could Robert comment on the whether the Ukraine experiments observed this or how they circumvented the problem? If indeed it is a problem. Michael Price Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3812