X-Message-Number: 15122 Date: Sun, 17 Dec 2000 21:50:00 +0000 From: Phil Rhoades <> Subject: Brain lipofuscin concentrations Ben, >Message #15119 >Date: Sat, 16 Dec 2000 07:26:50 -0500 (EST) >From: Ben Best <> >Subject: Re: An assist to CPAs and Ice-Blockers (Erratum) > >On Sat, 16 Dec 2000, Ben Best wrote: > > > CryoProtective Agents (CPAs) and Ice-Blockers can prevent > > ice-formation and promote vitrification. But Ice-Blockers > > typically do not cross cell membranes. And CPAs are always > > challenging to perfuse/diffuse because both their toxicity and > > viscosity vary inversely with temperature. > > In my efforts at pompous simplicity, I misstated the >facts. CPA viscosity does vary inversely with temperature >-- so that the lower the temperature of introduction, the >more difficult it is to get the stuff to perfuse through >blood vessels and diffuse into cells. However, CPA toxicity >tends to vary DIRECTLY (not inversely) with temperature >-- meaning that it is much less toxic when introduced at >lower temperatures. Therein lies the trade-off: how to >introduce the CPAs at a high enough temperature to >minimize viscosity, but at a low enough temperature >to minimize toxicity. > > Also, by the time genetic engineering is sophisticated >enough to modify genes so as to manufacture the "designer" >insulin-receptor of my fantasy, genetic engineering should >also be able to add genes for production of ice-blocker >proteins in the cells of mammals. If these proteins are >innocuous enough, they could be present at all times in >the cell without much harm. After all, if cells can >function adequately with large amounts of lipofuscin, There is a group of inherited human disorders (and their equivalents in other animals) collectively called Batten's Disease that arise out of mutational defects in the removal/processing of lipofuscin - this causes very nasty terminal neuronal diseases in infants to adolescents. It is true that lipofuscin does accumulate in older people but I would be careful about saying that people can "function adequately with large amounts of lipofuscin". >they should be able to tolerate some otherwise non-functional >ice-blocker proteins -- which don't need to be present in >high quantities to be effective. This is an advantage over >my proposed insulin receptor in that there is no time-critical >procedure to be applied in a cryonics emergency -- although >it is still time-critical that cooling occur rapidly after >deanimation. > -- Ben Phil. - Philip Rhoades Pricom Pty Limited (ACN 003 252 275) GPO Box 3411 Sydney NSW 2001 Australia Mobile: +61:0411-185-652 Fax: +61:2:8923-5363 E-mail: Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15122