X-Message-Number: 10664
Date: Sat, 31 Oct 1998 08:10:24 -0500
From: Thomas Donaldson <>
Subject: CryoNet #10658 - #10663

Hi everyone!

To Jan Coetzee: It helps us to give your source. AT least one article
discussing these results appeared in the latest issue of NATURE.
Moreover, there is another place to look for new neurons. The lining
of the ventricles in several animals produces cells which can 
differentiate into neurons and migrate elsewhere. Unfortunately these
scientists did not study that in humans, but given its occurrence in
other mammals I suspect (in the absence of experiment) that it 
happens in humans too.

To Mr. Delaney: Yes, the effects of drugs on lifespan is obscured by
the fact that mice come in all kinds of breeds. However your claim
that the comparison is with (say) hypercholesterolemics versus normals
is WAY too much exaggerated. Furthermore, if a drug causes some of the
same effects as CR, it may well show some of the symptoms of CR in 
animals receiving it. As a matter of fact, most of the drugs I listed
were not found to have an effect on aging by established researchers
into aging. That has always seemed to me to be a very interesting 
fact which tells us something about motivations. The only way to 
decide, in such experiments, whether or not CR may have played some
implicit role is to study the actual experiment in detail. Most important,
even when the animals show a slight loss of weight, it does not match
that of CR animals. Please read the articles again.

As for glucose metabolism, yes, it's true that experiments with the
drugs I suggested have been done. If that is all you mean, then I
agree with you. However if there are scientific papers actually 
looking at the relation of these (or other metabolism-changing drugs)
in relation specifically to CR, then please give me the references
at once. I read up on work on aging too, and if such research is going
on I'd like to know just where.

Finally, as for the issue of development after puberty, many men know
very well of at least two changes not obviously the simple result of
aging --- and on animal parallels they are likely to be development.
The first is balding: loss ofhair at the top of the head. The second
is whitening of the hair, or graying. The animal parallels are those
of some monkeys which also have male baldness; and gorillas, for 
instance, will show a graying of hair about their shoulders in male
gorillas when they reach a certain age --- after puberty but certainly
not in old age. There are probably other developmental events too:
one I know of is the filling of collarbones with bone rather than
the cartilage that remains there until early adulthood (somewhat 
changing the posture of younger men compared to older men, and similarly
with women). You may wish to claim that all of these changes in human
beings are those of aging. You may wish to claim that ANY change
occurring after puberty must necessarily be a sign of the decline of
aging. If you aren't simply playing with definitions (well, after all,
puberty itself could be considered a sign of aging!) then these 
changes deserve to be at least considered as developmental changes.

There is a problem with using CR to explain results with drugs. Usually
the lifespan extension found is too large to be explained simply by
CR, given the condition of treated animals. Not only that, but CR
explains nothing at all. We just have to go back a step and ask why
CR might increase lifespans. And often the scientist doing these 
experiments also provides an explanation of their effect, a much more
cogent explanation than simply saying CR. No, unfortunately these
explanations aren't followed up as closely as they should be. But in
terms of telling us something about how aging works, as hypotheses
they do much better than simple repetition of CR. After all, some
of us are looking for ways to intervene and even reverse aging, and
though CR IS a way to intervene, we'd like to know lots more.

			Best and long long life to all,

				Thomas Donaldson

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