X-Message-Number: 7859 From: Brian Wowk <> Date: Sun, 16 Mar 1997 00:11:30 -0600 (CST) Subject: Reply to Jan Coetzee "Jan Coetzee" <> writes: >If so much repairing is going to be necessary why won't the cryonics >organizations offer a formalin washout before freezing to save guard >against equipment failure? Sure there are problems with formalin but I >think on the whole it is saver on the long run! Experiments with fixation followed by freezing have shown that fixation disrupts cell membranes so that ice (which normally only forms outside cells) penetrates cells, causing intracellular freezing. Intracellar freezing is very damaging, and we want to avoid it. Fixation and vitrification is an interesting idea (I believe first proposed by Mike Darwin many years ago, and featured in Drexler's book, "Engines of Creation"). Personally I'd rather be just vitrified, and accept the risk of storage failure. Viable (or nearly viable) cells are going to be a lot easier to repair than cells where everything has been cross-linked at the molecular level (what a mess for future repair engineers!). Re: Cryo Journal Club #5 The size of cracks formed in vitrified solutions depends on the temperature at which they crack. If they crack near Tg, cracks are large and few. If they crack far below Tg (with large accumulated stresses), vitrified solutions shatter into many small pieces. These tests have only been performed on pure solutions; nobody knows if these same principles apply to organs. *************************************************************************** Brian Wowk CryoCare Foundation 1-800-TOP-CARE President Human Cryopreservation Services http://www.cryocare.org/cryocare/ Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=7859