Re: Bio: Premature Aging; Also, Telomerase (was: Transplants)

Anders Sandberg (
28 Oct 1997 10:02:27 +0100

=- deluxe -= <> writes:

> Are there measurable hormonal levels or other factors which can be
> atributed to say, my accelerated growth?

The human growth hormone system is relatively well understood. The
hypothalamus sends GHRF (Growth Hormone Release-Factor) and
Somatostatin (growth hormone inhibiting factor) to the anterior
pituitary (there might be some other chemicals involved here too). The
pituitary gland releases GH, growth hormone (somatropin) which
stimulates growth of various tissues in conjunction with hormones
secreted by the thyroid, the gonads and adrenal cortex.

It stimulates the productions of several polypeptides called
somatomedins from the liver, which are apparently responsible for most
of the anabolic effects (there are known receptors for somatomedins on
liver cells, fat cells and cartilage cells).

GH stimulates protein synthesis and the uptake of amino acids
especially in skeletal muscles, while the somatomedins appear to also
act on the muscles and the cartilage at the epiphyses of long bones,
thus influencing bone growth. These hormones have complex effects on
the carbohydrate metabolism, and act together with glucocorticoids to
cause lipolysis (i.e. the decrease of body fat).

I guess that there are a lot of factors here that could lead to fast
growth and a large adult size, both external factors like diet and
internal factors like the amounts of hormones secreted, how strongly
they affect different cells, the "development program" which
determines the hormonal changes during childhood and puberty and
various obscure interactions with other hormone systems. A lot of this
is likely genetic, if you have (say) genes for more efficient
somatomedin receptors a similar amount of hormones will make you grow
more than another person with normal or less efficient receptors (the
balance of hormones is dynamic, so just increasing the amount of
hormones doesn't necessarily increase the effect, since there are
negative feedback loops in the system).

> Since we were originally discussing how we could grow human body
> parts to adult size in a short period, could we then just manipulate
> the chemical relationships which naturally exist in the body to
> encourage a hyper-growth state???

As I have already pointed out, it is unlikely that we could get "hyper
growth" (i.e. growth orders of magnitude faster than normal
development), at least in differentiated tissue. Growing huge amounts
of (say) skin cells or undifferentiated neurons, no problem, but if
you want a functional kidney you need some very elaborate
differentiation to occur which cannot be speeded much since it depends
on the diffusion coefficiencts of various chemicals. But it seems
reasonable to get faster growth by manipulating the hormone levels in
cultured tissues or in people, it is just that it won't be any

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y