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 

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 
> 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.

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