X-Message-Number: 12477 Date: Wed, 29 Sep 1999 11:45:41 -0700 (PDT) From: Doug Skrecky <> Subject: more on reversible fixation In Message #12466 Thomas Donaldson <> wrote: > Fine. You say that brains have been completely embalmed ie. the substance > penetrated at the right concentration into the entire brain. Please give > a reference for this. > Archives of Medical Research 27(1): 37-42 1996 (human brain fixation) Archives of Medical Research 27(2): 127-132 1996 (52 lb dog fixation) I strongly suspect that the development of fully reversible chemical fixation could not use any of the highly reactive fixatives in use today. Since formaldehyde and other such chemicals are very reactive with proteins, they bind to them so strongly, that prying the proteins away would almost inevitably involve a considerable amount of damage. If reversible fixation is to be developed at all, it would likely have to use much less reactive chemicals. These might not result in complete inhibition of the enzymes which largely mediate tissue deterioration, so indefinate preservation of tissue would not be possible with these. Instead it seems likely that any reversible fixation protocol would see use only for short term storage so as for example, to greatly lengthen the period that transplantation organs could be safely stored. This could also be used to buy time for the lengthy procedures needed for cryopreservation or lyophilization. In might even be used to protect against cryo (or lyo) -protectant toxicity. After looking through my library, one research report which commended itself for further attention was one which dealt with the effect of grape seed proanthocyanidins on intestinal enzymes. (Enzyme Protein 48: 51-60 1994-95) These condensed tannins are capable of forming complexes with proteins, and oral feeding at the 2% level in diet results in partial inhibition of intestinal enzymes. This inhibition can easily be blocked by detergents, and even completely reversed by pancreatic-biliary juice. IMHO, perfusion with proanthocyanidins looks to be a promising line of investigation in the development of a possible reversible fixation protocol. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=12477