X-Message-Number: 26749 From: Subject: Brain vitrification Date: Mon, 01 Aug 2005 23:13:04 +0000 --NextPart_Webmail_9m3u9jl4l_13890_1122937984_0 In Cryomsg 26744, Bob Ettinger wrote: >> The references cited (Lemler et al) were useful and encouraging, but glossed over some points. A hasty reader might conclude that brain vitrification with liquid nitrogen storage is a done deal... The lowest reported temperature was - 140 C, and the period of time at that temperature was not given. << Brain vitrification with liquid nitrogen storage is a done deal, and has been for some time, subject to the caveat that whole brains vitrified with current solutions will not spontaneously resume function after warming because of cryoprotectant toxicity (and fracturing if cooled all the way to liquid nitrogen temperature). As Bob should know, between -140 degC and -196 degC there are no further damage mechanisms other than fracturing. >> ...and also that rabbit kidneys can be vitrified well enough for routine transplant. This does not seem to be the case. The rabbit kidney results could be read as long term survival of vitrified transplants, but it didn't actually say that, << Since it didn't actually say that, I don't know why it could be read as that. The M22 kidney paper was published in the journal Cryobiology last year, and is well-known in the vitrification field. I'm pretty sure it was discussed on CryoNet, but even if not I'm surprised it was not noticed on PubMed by cryonicists who follow vitrification research. The full text is available at http://www.21cm.com/pdfs/cryopreservation_advances.pdf >> And the composition of the solution "M22" was not given, so there is no way for us to do any independent verification. << The formula for M22 has been in the open literature for more than a year. It is in the above paper, along with many other properties such as glass transition temperature, melting point, nominal pH, and toxicity results. Two other properties presented at this year's Society for Cryobiology meeting were a critical cooling rate (minimum rate for cooling large volumes without ice formation) of 0.1 degC/minute, and a critical warming rate of 0.4 degC/minute. There is a photograph of a large volume of M22 vitrified without ice formation in the middle of the page http://www.alcor.org/sciencefaq.htm >> The secrecy issue is an unsolved problem... (we should) Publish our results freely as they come... << Alcor's cards are now on the table. David Stodolsky wrote: >> The commercially-oriented tissue preservation work may, therefore, not be what yields the best result for cryonic suspension. << The structure/function tradeoff is not as stark as it appears. Decent structure preservation is typically a pre-requisite for good function preservation. However, as I've already told Bob privately, I don't believe there is any vitrification solution in the world that gives good functional recovery under the time/temperature/concentration conditions of human cryonics. There are only functional results under less damanding conditions, from which we suppose that less toxic solutions cause less biomolecular havoc in cryonics. As for "commercially-oriented tissue preservation", the only vitrification solution for which structural brain vitrification data has been published is a commercial solution developed to minimize toxicity, so for now there is no dichotomy. ---Brian Wowk --NextPart_Webmail_9m3u9jl4l_13890_1122937984_0 Content-Type: text/html [ AUTOMATICALLY SKIPPING HTML ENCODING! ] Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=26749