X-Message-Number: 15511 Date: Thu, 01 Feb 2001 04:50:51 -0500 From: Paul Antonik Wakfer <> Subject: Comments on Viability and Self-Repair - #15442 >Message #15442 >From: >Date: Wed, 24 Jan 2001 15:12:48 EST >Subject: Grimes again [SNIP] >Again, the 53% (now 66%) "viability" of rat brain slices by the K/Na >criterion has been interpreted differently, in public, on Cryonet, by two >people affiliated with the sponsoring organizations--one saying it means 66% >on average over the cells, with the variance unknown or unreported; This is what I have stated and is the correct interpretation. >the other >saying it means 66% of normal function for each and every cell, which seems hardly likely. Not only is it hardly likely, but it is not possible to be measured and therefore is most certaily an incorrect interpretation. However, I do not recall where this was stated or by who. Would you please enlighten us with that information in a direct quote? >Also, as I recall, extending the period of incubation did not >result in self-repair and improvement of function. It needs to be pointed out that incubation is *not* equivalent to the healthy environment which would be obtained by implantation. Implantation of a rabbit kidney with only 66% viability as measured by the K/Na ratio has, in the past, allowed recovery of full function, even when it was the only kidney. Ie. even at 66%, it provided enough kidney function to keep an otherwise heathly rabbit alive until it was fully healed. >Another little note--which I do not think I have mentioned previously--is >that, according to my impression (anyone who knows, correct me if I'm wrong), >the K/Na test only gives good results if very fresh specimens are used, "Fresh" here means merely having suffered little ischemic time and therefore little damage, ie. still "alive". This not a "disadvantage" of the K/Na test as Mr Ettinger seems to be implying. Instead, that "fresh" tissues is necessary for a good K/Na ratio is a primary indication that the test reliably measures how near to "living" (viable) the tissue actually is! >with >much worse results if there is post mortem delay. In the case of cryonics >patients, there is almost always post mortem delay, and I believe more than a >full day in the case of the last two Alcor patients. This depends very much on the *kind* of post mortem delay. When I was involved in cryopreservations with Mike Darwin, I recall at least two patients which were washed out immediately with essentially the same perfusate which allowed dogs to be revived from over 5 hours at just above 0'C. These patient arrived at the facility ready for cryopreservative perfusion with practically no damage whatsoever. It is virtually certain that their K/Na ratios would have been very high. To quote from one of the scientists involved. "To put this in a cryonics context, some years ago a K/Na ratio test was done on kidney slices taken from an Alcor patient prior to glycerolization who received good, prompt cardiopulmonary suport. The results were very good. Of course, no one has done such a test on the brain tissue of a cryonics patient prior to glycerolization, but if cardiopulmonary support is good, the result should be good." >But it is not at all clear--at least to me, and I have asked others for >advice on this--how well the K/Na criterion correlates with other >physiological criteria of function, such as gas exchange, glutamate uptake, >and many others. Since a good K/Na rato requires functioning mitochondrial energy production, from intake of oxygen and output of CO2, it is obvious that gas exchange must also be good (and is thus an unnecessary measurement). Since there is more than one kind of cellular "glutamate uptake" (as a regular amino acid through cellular membranes, or for neurons reuptake at synapses), it is not clear what Mr Ettinger is referring to here. If to the neuronal synapse reuptake, it is also not clear why he would single out glutamate from the many other important neurotransmitters. However, the reuptake of glutamate at synapses while requiring energy, requires far less than the maintenance of K/Na ratio (which in some cells requires over 90% of the cellular ATP generation capacity). However, it is valid that neurotransmitter reuptake is not measured by the K/Na ratio and will need to be verified for brain tissue at some point. That, in fact, is one of the longer-term goals of INC. Obviously, until Mr Ettinger specifies the "many others", I cannot comment on them. >Further, it seems reasonable to me that one of the more important functional >tests for neurons would be the electrical activity. After all, Suda's old >experiments were deemed very important because his corticograms resembled >normal ones to a fair extent. And I have mentioned that Pichugin did some >work for CI a couple of years ago with rabbit brain pieces, using a glycerol >CPA, and after rewarming from liquid nitrogen temperature he was able to show >coordinated electrical activity in networks of neurons. The report appeared >in The Immortalist, and will be added to our web site before long. This is a repetition of earlier statements, and as I stated before, electrical activity is subsidiary to measurement of cellular health by a test such as the K/Na ratio. Ie. electrical activity (but not coordinated brain waves) can occur from cells with quite useless energy generation structures. To emphasize this again, Guyton "Textbook of Medical Physiology" states on page 60 that "100,000 to 50,000,000 impluses can be transmitted by nerve fibers, the number depending on the size of the nerve fiber and several other factors, before" the concentration differences of sodium and potassium require reestablishment by energy from the cell. And also, once again, EEGs (corticograms) are not related to measurements on brain slices or even "pieces". -- Paul -- The Institute for Neural Cryobiology - http://neurocryo.org A California charitable corporation funding research to perfect cryopreservation of central nervous system tissue for neuroscience research & medical repair of the brain. Voice-mail: 416-968-6291 Fax: 559-663-5511 Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15511