X-Message-Number: 825 Date: Wed, 13 May 92 17:04:39 PDT From: (Bob Smart) Subject: CRYONET sci.bio tidbit, part 1 I found the following on sci.bio, and thought the cryonics community might be interested: In article <>, (Robert Bradbury) writes: > In article <> > (Allen Smith) writes: > > > > If we're going to really stop aging, then we'll need to figure out > >how to get neurons to regenerate. Some clues can probably be found in the > >nasal neurons (which keep dividing); what's the current status of research > >on the cause of this difference? > > I don't think we have to look as far as nasal neurons. In the 3/27/92 > issue of Science, p 1707, BA Reynolds and S Weiss make a strong case for the > existance of neuronal stem cells which can differentiate into neurons and > astrocytes in adult mice when they are exposed to EGF. Since the receptors > for EGF are found in the human CNS this may be expected to work in humans > as well. They say, "Taken together, these findings suggest that a population > of embryonic stem cells may survive in the adult brain in a dormant, > nonproliferative state." I don't know if this has been discussed in the > neuroscience topic but I think this is hot stuff! The thing I find amazing > is that their data would indicate that these are 1.5% of the cell population. > > Reflecting on this, it seems to me that there are stem cells in the bone marrow > which can regenerate our blood cells, stem-cell like hepatocytes which can > regenerate the liver, smooth muscle cells or perhaps stem-cells, that divide > and contribute to arteriosclerosis when stimulated with FGF and of course > precursor cells in the skin, intestine and uterus which undergo division > and differentiation to regenerate surface cells. All of this leads me to > conclude that there may be precursor cells left around for everything. > All they need is the right stimulation and voila, we have new tissue. --------- Date: Wed, 13 May 92 17:06:14 PDT From: (Bob Smart) Subject: CRYONET sci.bio tidbit, part 2 This followup also appeared in sci.bio: In article <>, (William Calvin) writes: > Yes, there are undifferentiated neurons left around in some areas of > brain; if there were some in substantia nigra, then bringing them on-line > might well work even better than L-DOPA. > > But no, they're not going to be much help in cases of cortical damage, > even if available. Development occurs in sequences, building on prior > stages (pathfinder cells being the most dramatic examples, some of which > then die like scaffolding being removed). Unless you can recreate the > developmental sequence, a neuron's exploratory processes may simply get > lost (the typical spinal cord regeneration problem). > > And no, too, regarding much higher function that depends on memory that is > help in a pattern of cell connections. The reason that neurons don't > divide during life is probably that it would destroy the established > pattern of connections with thousands of other neurons, that constitutes > the memory engram. > > William H. Calvin > University of Washington NJ-15 > Seattle, Washington 98195 FAX:1-206-720-1989 --------- A fanatic is someone who does what he knows that God would do if God knew the facts of the case. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=825