X-Message-Number: 3923 From: (H Keith Henson) Newsgroups: sci.cryonics Subject: Re: glycerol questions Date: 25 Feb 1995 12:00:18 -0800 Message-ID: <> References: <> <> Re this thread, Eugen Leitl <> has several questions: >Apropos glycerol, is dimethylsulfoxide used in modern commercial >cryoprotecting agents? Maybe DMSO/glycerol mixes? While I cannot speak for the others, Alcor does not use DMSO. > Additionally, >it would be extremely interesting to learn what methods/sequences >are used by commercial cryosuspension companies. I hope this isn't >classified or any such thing? A simple outline would suffice. The methods have been published in considerable detail in, for example, Cryonics magazine. Write Alcor and ask for them by email or hardcopy. >Especially, the following issues are of interest: >1) Is the blood removed during cryoprotectant infusion? Before usually. Field washout (with Viaspan or similar solutions) typically reduces hemocrit to 1-1.5 percent (down from normal ~30 percent). This is further reduced as circulating lower glycerol concentration solution is discarded. >2) Must the body be precooled? (say, 4 degree Celsius). There are *strong* reasons to get body temperature down into this range as fast as possible. >3) Is oxygene/glucose provided during cryoflood to counteract > brain damage? Depends on patient history. If the patient has undergone more than about 20 minutes of no flow to the brain, we do not oxygenate at all to avoid reperfusion injury. We may change this cutoff point downward in the future. For those with little or no ischemic injury, we oxygenate (and supply glucose) all the way to the end of cryoprotection. > What is the maximum tolerable process time? Unknown, unknowable. Various groups have recovered dogs after cooling to 4 deg. C for several hours (I don't know the current record. 6?) It is our opinion (based on low levels of brain swelling and analogy with organ transplants) that a rapidly cooled patient has a perfusion window of 24-36 hrs. Less is, of course, better. >4) What is the temperature program for whole body/brain only > freeze? While I hacked together the first program for cooling some years ago, the parameters have been changed so much since then that I no longer know exactly what curves they are using. In those days, we maintained a delta T from inside to outside temperatures. I think that is still the method for first stage cooling, but near the glass transition, there is an extended soak to relieve stresses. >5) Is brain tissue frozen en block? (Would cutting up > introduce too many artefacts?) Yes and yes. >6) Is process/result monitored? Are freeze damage estimations > done? (xRay diffraction, bioactivity of a thawed sample, etc.) Yes on the first, and no on the second. We have looked at Xray and MRI, but mostly to see how uniform the perfusions are. 7) Is liquid nitrogen temperature enough? Yes, Kevin can point you the article. > Is an inert gas blanket > used against tissue oxidation? The patients are *submerged* in LN2. We do worry about LOX getting into the LN2, but other than cleaning out the dewars when we move the patients we have not done anything about this. >8) Is the current policy to minimize preprocessing or vice versa > and are the deviations protocolled? Is a copy stored with the > the tissue? Policy is to do what we can as fast as economically possible. Records are kept as to what happened in each case. I know some records are placed in with the patients, but most is kept externally. >9) Is there any noticeable research on cryomethods going on > in the companies? How is it financed? Any breakthroughs? Yes, financed mostly by donations (no matter what they are called). Re "breakthroughs," lots of little points of progress, but I don't expect to see a whole mammal to go down to LN2 and be recovered alive and functional before full scale nanotechnology comes on line. In spite of Dr. Suda's work, I don't even expect reversible brain cryopreservation to be demonstrated prior to that point either. I would be absolutely *delighted* if it turns out I am wrong. (And I expect to be flamed unmercifully for expressing this opinion.) >10) Are legal problems real problems? Is the Pope Catholic? My off-the-cuff estimate is that Alcor has spent 5 times as much money on legal bills and legal forced cost since 1988 than has been spent on all cryonics research in that time period. (Organ work excluded.) > _Is_ the legal status > of cryosuspended person "deseased"? Any indications of > change? No, legally the state considers them *dead*. This status has good and bad points. Since most of us pay for cryonics with insurance, Alcor can collect. But it leaves those in suspension without much in the way of legal protection (except what the living members provide). >Yes, these are a lot of hard questions. Yet I think that by answering >them the cryosuspension firms would show a greater transparency >and thus gain a higher credulity level. These are *easy* questions! Most of them have been discussed in fine detail over the last few years. Write for a list of postings on cryonics (close to 4000 by now). Or ask Alcor () to send you a copy of Cryonics--Reaching for Tomorrow. (If you live outside of the US, at least send them the cost of postage.) Keith Henson Alcor Board Member, but speaking for himself. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3923