X-Message-Number: 2404 From: whscad1!kqb (Kevin Q Brown +1 201 386 7344) Subject: CRYONICS How Much Cracking Really? I have appended below a brief article from the August 1993 issue of The Immortalist. It concerns the cracking problem, which prompted the long and productive "cold room" thread on CryoNet a few months ago. ** Robert Ettinger reports that cracking has *not* been observed in recent experiments at CI and BioTime and thus calls into question the need for a "cold room" to prevent cracking. Can anyone shed more light on this? Kevin Q. Brown INTERNET or PS: I assume that electronically distributing the article below to a small group of people falls under the "fair use" doctrine of copyright law. Alternatively, consider it a free advertisement for The Immortalist. (For contact & subscription information for The Immortalist and other cryonics-related publications, send email to me with the Subject line "CRYOMSG 0004".) ** The cracking problem is that organs, and people, frozen to liquid nitrogen temperature, crack. I think that this is mostly due to unequal contraction of adjacent tissues. These cracks become obvious upon rewarming. Although the cracks are generally "clean breaks", they are numerous enough and large enough to cause massive disruption of tissues. If the temperature does not ever drop below the glass transition temperature, though, there may be much less cracking. ----- How Much Cracking Really? Alcor has reported cracking in patients frozen to liquid nitrogen temperature -- some cracks at all levels, from obvious surface cracking to micro-cracks. This has resulted in recommendations to store patients at higher temperatures, perhaps in the vicinity of -130 C. Various Alcor people have gone to great pains to design ingenious "cold rooms" for this purpose, and Cryonics Institute has done some investigation of possible cryostat design for this purpose. However, the Cryonics Institute experiments with sheep heads, frozen to liquid nitrogen temperature and later thawed, have *not* shown cracking at the level of naked-eye inspection, either on the skin surfaces or on the brain surfaces (visible through a window cut in the skull). Furthermore, as reported here many months ago, in several cases we got good reperfusion, not showing the evidence of leaks or broken blood vessels that would be expected if there were any important cracking. Recently, according to Dr. Hal Sternberg, BioTime has gotten consistently good results with hamsters, using new perfusate formulations. They also get good reperfusion, after warming from liquid nitrogen temperature, with no evidence of cracking at any level, including examination with the light microscope. Storage at higher temperature might still be desirable, and might also save money. But the importance of doing this to avoid cracking is not at all clear, in light of the CI and BioTime results. If we can get full details of the Alcor procedures that resulted in the cracking, perhaps some of this can be clarified. R.E. ----- Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2404