X-Message-Number: 15298 Date: Mon, 8 Jan 2001 23:31:31 -0500 (EST) From: Charles Platt <> Subject: Ettinger Toxicity Mythology I recently received the following message from a scientist who does not normally read CryoNet, but has seen some of the Ettinger posts, and was sufficiently disturbed by the inaccuracies to make a quick reply. Like many researchers in this field, he prefers not to have his name associated with cryonics and asks to be described as "a scientist who has ties to the Institute for Neural Cryobiology, and who has personal knowledge of the vitrification solution used by Alcor". In response to Ettinger's suggestion that the vitrification solution now being used by Alcor is probably more toxic than the simple glycerol cryoprotectant used at CI, he writes: ----- 1) The vitrification solution used by Alcor is far less toxic than glycerol at high concentrations in either whole kidneys, kidney slices or brain hippocampal slices. In other words, a given high concentration of Alcor vitrification solution will be much less toxic than the same concentration of glycerol. Therefore the approximate 65% concentration of Alcor vitrification solution that is used to achieve neurovitrification will be much less toxic than the 75% glycerol apparently used in the CI method. Therefore Alcor's new method will preserve higher cellular viability than the CI glycerol-based method. This is expected to be true whether or not vitrification is actually occurring (such as in poorly-perfused tissues that freeze instead of vitrify). 2) In support of these facts, the most recent rat hippocampal brain slice studies performed by the Institute for Neurocryobiology have found that slices vitrified and rewarmed using dilute Alcor vitrification solution retain 66% of K/Na ion pumping ability (which is a very comprehensive measure of cell function). In contrast, all slice viabilities obtained after freezing in glycerol (at a variety of concentrations) were less than 5%. In summary, the view that Alcor's new technology sacrifices viability for possibly better structural preservation is a myth. The move to this new technology is well-justified based on toxicity issues alone. ---- End of forwarded message. I should add that Bob seems to have misunderstood the term "percentage cell viability." So far as I can tell from his posts, he seems to think that (for example) "50% cell viability" means half the cells are functional, while the other half are irrevocably damaged. This is not correct. As is clear in the above text, the % viability that Bob quoted in one of his previous posts is actually a measure of how well, on average, the cells are able to perform. Thus, a kidney whose cells are 80% viable can in fact recover full function after being transplanted. This is a very important point, since the same kidney could not regain function if 20% of its cells had been irrevocably damaged. Bob makes a habit of warning readers not to believe sources at other cryonics organizations, but of course the same warning should be issued regarding his own assertions, bearing in mind his lack of knowledge of biology. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15298