X-Message-Number: 15092
Date: Thu, 7 Dec 2000 21:10:41 EST
Subject: new research evaluations

We have now had reports from an independent Canadian service laboratory on 
another set of sheep brain specimens. Part of it is posted on our web site.

As usual, the lab did not know which specimens were which, or for that matter 
how any of them had been prepared, so there was no chance of bias in the 

Previous evaluations had shown clearly that the current CI procedure--one 
pass perfusion with 75% glycerine--is very much less damaging than 
uncontrolled or "straight" freezing. (Of course, it is possible that even 
uncontrolled freezing may prove reparable by future fully mature 
nanotechnology or equivalent, but that is another story.) However, various 
people have wondered why we have not used ramped or gradually increasing 
glycerine concentrations, instead of one pass at full strength.

Naturally, we have been fully aware that many reports in the cryobiological 
literature have indicated that ramping or stepped concentrations have seemed 
better--going back many years, at least to Farrant, who is often given credit 
for pioneering this approach. However, as we have explained many times, our 
main reliance is on results that we see for ourselves. We do not and cannot 
rely on the reports of others,  although we can use them for help and 

The reports of others are all too often incorrect or misleading in some way, 
sometimes because of very different experimental conditions, such as working 
with tissue samples instead of whole brains; or working with young and 
healthy animals under ideal conditions instead of with old, sick, damaged 
patients after substantial delays; or because of individual variation and 
lack of statistical significance; or because artifacts were introduced (or 
not) in the act of analysis; or occasionally even because of selective 
reporting. (We know, in confidence, of at least one well known cryobiologist 
who knowingly falsified reports.) 

Our own observations heretofore simply have not shown any advantage in 
stepping or ramping, which may also add to the time demanded and to that 
extent is bad in itself. Further, ramping or stepping can sometimes result in 
edema, which must be monitored and controlled, whereas with one pass at full 
strength we never get edema.

But we wanted to go over this ground again, with evaluation help from 
independent professionals. In a previous set of samples, one pass at 75% was 
found to be a little better than stepped 10%-20%-30%. In the latest set we 
added stepped 10%-20%-40%-75%, and this was judged to be (possibly) just a 
trifle better, averaged over three samples, than one pass at 75%.

From literature reports, it seems unlikely that continuous ramping would show 
a significant difference over stepped ramping, but nevertheless we will soon 
try that too, just to be sure.

We also have many other trials planned, with several different variables of 
preparation--and also different methods of evaluation, including histology 
(microscopy), physiology (chemistry), and neuronal activity 
(electrophysiology). Whenever we get clear and consistent results showing 
something better than our current procedure, we will switch to that, and that 
will almost certainly be some time in 2001.

Robert Ettinger
Cryonics Institute
Immortalist Society

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