X-Message-Number: 1485 From: Ben Best <> Date: Mon, 21 Dec 1992 19:00:00 -0500 Subject: more on cryoprotectants ERRATA AGAIN: Garret Smyth is correct, I meant "emulsion", not "suspension". (Double-entendres cloud the mind.) Canada Remote Systems, my network host, periodically delays my USENET messages several days and then sends them to me in a batch -- which slows down my response time. (This is an excuse, not an apology.) In any case, my CRYONET dialogue about cryopreservation seems to be winding-down. I need to study the literature more and formulate my thoughts before doing any more mouthing-off -- and I will attempt to crystallize this effort in an article in the Winter issue of CANADIAN CRYONICS NEWS. But a few parting thoughts: REPLY TO MIKE DARWIN I am not suggesting that theorizing is a substitute for research, but it can help research to ask the right questions. Thank you for your comments about dehydration damage as opposed to freezing damage, but since we don't know what structures are the most essential to preserve, can we really be sure that 6M glycerol is better than 4M? In Greg Fahy's December 1991 CRYONICS article he comments that 6M glycerol "has produced either superb preservation or preservation marred by massive cellular dehydration, depending on the glycerolization technique." What technique avoids dehydration? I have been fantasizing about using a chemical to accompany glycerol which would cause non-destructive puncturing of cell membranes -- thereby allowing easy perfusion. I can't comment on Suda's data, since I haven't seen it. But if Greg is in possession of it, why can't you (or I) get a copy? Greg's vitrification solution of DMSO, propylene glycol and formamide sounds more appealing than DMSO alone, but I'm still wondering why he excluded glycerol. If my theory of high perfusion with low molecular weight is correct, formamide (HCONH2) with a molecular weight of 45 would be excellent. Greg sounds so awesomely confident in CRYOMSG 486 when he says "I may or may not be able to work out a technique for vitrifying the brain, but I can certainly reduce ice crystal growth enough to preclude structural damage, which would be good enough." If he is right, why isn't implementing his techniques the NUMBER ONE priority of cryonics research? Did he make his statement before discovering that his DMSO-propylene glycol-formamide mixture only vitrified the grey matter of dog's brains, and not the white matter? It sounds to me as if what is needed the most is a low molecular weight lipophilic cryoprotectant that can be added to Greg's mixture to protect the white matter. -- Ben Best (ben.best%) -- Canada Remote Systems - Toronto, Ontario World's Largest PCBOARD System - 416-629-7000/629-7044 Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=1485