AGING news from Science Week

Max More (
Sun, 16 Nov 1997 10:57:21 -0800

From: "Prism Express" <>
Organization: Prism Express
Date: Thu, 6 Nov 1997 09:29:39 -0600
Subject: Science-Week 7 Nov 1997
Priority: normal


A Free Weekly Digest of the News of Science

November 7, 1997

There may be controversy over the importance of genetics versus
environment in the human aging process, but there is no
controversy about the dominant rule of genetics as the
determinant in aging differences between species. Man lives 72
years, the cat lives 15 years, the mouse lives 27 months, the
fruit fly lives 40 days, and the nematode worm lives 15 days --
the differences attributable to the differences in genomes.
Nevertheless, beyond the attribution to genetics, there is almost
nothing known about the particular genes involved, and even less
about any proteins expressed by these genes. Within the human
species, there are also many primary mysteries of the aging
process waiting to be solved. Why, for example, in Alzheimer's
disease, a neurodegenerative disease with a heavy genetic
component, is it common to have the onset of Alzheimer's disease
in identical twins differ by many years? The present consensus
among researchers is that within a species 35% of the variance in
the aging process is determined by genetic factors and 65% by
environmental factors. Caleb E. Finch and Rudolph E. Tanzi
(University of Southern California, US; Massachusetts General
Hospital, Boston US), in a review of current research in the
genetics of the aging process, suggest the role of genetics in
determining life-span is complex and paradoxical, and that life-
style and other environmental influences may profoundly modify
the effects of genetic factors. This is clearly a field searching
for its watershed. QY: C. E. Finch, Univ. Southern Calif., Biol.
Sci. (213) 740-2777 (Science 17 Oct 1997)

There are a number of critical questions concerning the aging of
the human brain, among them: 1) How is the normal aging of nerve
cells different from the normal aging of other cells? 2) How are
the changes seen in normally aging nerve cells different from the
changes seen in nerve cells affected by neurodegenerative
disease? 3) How is the normal aging of nerve cells affected by
systemic factors such as hormone levels? These are 3 important
areas of research in the biology of the aging process, and it is
apparent that important data will be appearing in the next
decade. There is preliminary evidence, for example, that estrogen
plays a protective role against aging changes in nerve cells.
John H. Morrison and Patrick R. Hof (Mt. Sinai School of
Medicine, NY US) review the differences between pathogenic neuron
loss in the human brain and neuron loss due to the normal aging
process, and the authors suggest that primary neurobiological
substrates for functional impairment in aging differ in important
ways from those in neurodegenerative disorders such as
Alzheimer's disease. They emphasize that it is an error to
consider the normal aging of the brain and Alzheimer's disease as
part of the same continuum of senescence. QY: J. H. Morrison
<> (Science 17 Oct 1997)

Hormones are signaling molecules secreted into the blood stream
by endocrine cells and acting on target cells that possess
receptors for the hormone. They have long been a subject of
research, testosterone having first been discovered in 1848. At
present, there are dozens of different vertebrate hormones that
have been identified, ranging from relatively low molecular
weight hormones such as steroids to peptide hormones such as
prolactin with nearly 200 amino acids in the peptide chain. One
essential fact concerning the signaling with which hormones are
involved is that hormones do not act in isolation. Nerve cells
can trigger the release of hormones and local chemical mediators,
hormones can influence nerve cells and trigger the release of
local chemical mediators and other hormones, and local chemical
mediators can modify the response of target tissues to the
actions of hormones. All of which partly explains the complexity
of endocrinology as a research area. Steven W. J. Lamberts et al
(3 authors at Erasmus University, NL), in a review of the
endocrinology of aging, point out that physiological changes have
usually been the focus when considering the aging process, but
there is evidence these changes are due to important reductions
in certain blood hormones that occur during aging in both men and
women. Replacement therapy, however, has not yet proven to be
both safe and beneficial. QY: S. W. J. Lamberts
<> (Science 17 Oct 1997)