Subject: (Maxey) emf & cell replacement? (fwd)
Date: Wed, 17 Jun 1998 101800 -0500 (CDT)
From: "Roy L. Beavers" <rbeavers@llion.org>
To: emfguru@hotmail.com
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---------- Forwarded message ----------
Date: Wed, 17 Jun 1998 08:53:43 -0500
From: Edward Maxey
To: "Roy L. Beavers"
Subject: emf & cell replacement?
Hi Roy,
This is for "Just Bill." Having read John Goldsmith's very penetrating
remarks it seems to me, from a surgeon's perspective, we need to
seriously entertain the possibility that the major EMF effect deals not
so much with cellular damage as compared to posssible adverse effects on
cellular replacement. Here again is the 3/17/98 NYT article on the
subject.
Welcome "Just Bill,"
Ed
- - - - - - - - - -
Studies Find Brain Grows New Cells
By GINA KOLATA
For years, neurobiologists clung to a fundamental truth: once animals,
or people, reach adulthood, they may lose brain cells but they can never
grow new ones. There were a couple of exceptions -- in birds and rats --
but the thought was that these were peculiarities of nature and not
evidence of a general principle.
But now, in experiments that experts call amazing, that dogma has been
overturned. Scientists have found that monkeys are constantly making new
brain cells in the hippocampus, an area of the brain used for forming
long-term memories. Moreover, they report, the production of new cells
is squelched when the animals are under extreme stress.
Experts say they fully expect that humans are no different and that
they, too, make new brain cells in adult life. That raises the glimmer
of a possibility of eventually treating degenerative disorders like
Alzheimer's or Parkinson's disease and injuries, like those resulting
from stroke or trauma, by prompting the brain to grow replacement cells,
researchers said.
It also means that neurobiologists must re-think their notions of how
the brain changes with learning or life experiences. The new study was
by Dr. Elizabeth Gould of Princeton University, Dr. Bruce S. McEwen of
Rockefeller University in New York and their colleagues.
"It means that there is a new mechanism for changing the organization
of the adult brain," said Dr. William Greenough, a psychologist at the
University of Illinois at Urbana-Champaign who studies learning and
memory in rats.
Dr. Fred Gage, a neurobiologist at the Salk Institute in San Diego,
said the implications were "fabulously interesting."
The investigators, working with marmoset monkeys, added two tracer
chemicals to the animals' brains: one that labeled cells that were
dividing, the process that gives rise to new cells, and one that labeled
mature nerve cells. Cells that were born during adult life and that grew
into mature brain cells would be marked by both chemicals.
With this method, the researchers looked for, and found, new cells in
the animals' hippocampuses. Gould estimated that thousands of such cells
were being made each day. She said she suspected other cells were dying
to make room for new ones, but her study did not count numbers of dying
cells.
The hippocampus was particularly intriguing for another reason, Gould
said. Earlier research had shown that when people are under stress, the
hippocampus shrinks in size. For example, people with tumors that pour
out the stress hormone cortisol have a diminished hippocampus. So do
people with recurrent depression and people with postraumatic stress
disorder, Gould said. It might be possible, she reasoned, that monkeys
under stress might decrease their production of new brain cells in the
hippocampus, making that area of the brain shrink.
To test the hypothesis, Gould and her colleagues stressed monkeys by
putting a male monkey who had always lived alone into a small cage where
another male was living. The intruder was terrified and cowered in the
cage, with a rapidly beating heart. When Gould and her colleagues
examined the brains of the frightened monkeys, they found that after
just one hour of this stress, the monkeys were making substantially
fewer new brain cells. The study is being published today in The
Proceedings of the National Academy of Sciences.
As so often happens in science, the seeds for the new view of brain
regeneration were sown decades ago, but were largely ignored. In the
1960s, Dr. Joseph Altman, a Purdue University scientist who is now
retired, reported that rats make new brain cells throughout their lives.
The cells were in the hippocampus and in the olefactory bulb, an area
used to sense smells, he noted.
"No one paid attention," Gould said. She attributed the reaction to
researchers' biases. "People thought that there was no way that such a
mechanism could exist in adult mammals," Gould explained.
Twenty years later, Dr. Fernando Nottebohm, who is head of the
laboratory of animal behavior at Rockefeller University, asked whether
brain cells were being born in adult birds. Bird brains, he noticed,
grow and shrink with the seasons, swelling when the animals need to
learn new songs to attract mates and shrinking after they had bred. He
wondered whether the swelling brains during breeding seasons could
represent the actual growth of new brain cells. At the time, Nottebohm
said, he knew nothing of Altman's work. Altman, he said, "was not being
quoted in books."
In a series of painstaking experiments, Nottebohm showed that birds
constantly make new brain cells and that the new cells replace old ones
that die. "There was a program of constant brain rejuvenation,"
Nottebohm said. "Parts of the brain were no different from the liver or
skin. Old cells died and new ones took their place."
In 1984, Nottebohm organized a meeting in New York that he called Hope
for a New Neurology. A colleague at Rockefeller, Dr. Arturo
Alvarez-Buylla, recalled that Nottebohm "was pushing the idea that in
the adult brain, there is no impediment to the formation of new
neurons." But, Alvarez-Buylla added, "people thought that was bordering
on fantasy."
Nonetheless, some researchers persisted, showing in rats and mice and
in tree shrews that new brain cells are born throughout life, at least
in the hippocampus and olefactory bulb. Dr. Alvarez-Buylla, for example,
recently found that adult mice make 5,000 to 10,000 new brain cells each
hour. The brain cells that end up in the olefactory bulb are born on the
walls of the ventricles, cavities in the brain that are filled with
cerebrospinal fluid. They travel in "little trains of cells" to their
destination, he said. Those that end up in the hippocampus are born
there.
But many scientists believed that monkeys and humans could not be
growing new brain cells, and certainly not in a area like the
hippocampus. "People believed that in order to store memories for a
lifetime, you need a stable brain," Gould said. "If cells are constantly
dying and new ones being produced, how would that be possible?"
Gould, however, was persuaded by the findings in other species. "Why
not monkeys?" she asked. Others also began seeking and finding brain
regeneration in monkeys, Gage said, although Gould is the first to
publish her findings.
The results are "very very provocative" said Dr. Ronald McKay, the
chief of the laboratory of molecular biology at the National Institute
of Neurological Disorders and Stroke in Bethesda, Md. They lead, he
said, to a host of other questions. How does the rate of nerve cell
regeneration change as monkeys, or people, grow old? What controls the
rate? How can it respond so rapidly to stress?
Nottebohm has another list of questions. One of the first imperatives
is to understand why the bulk of new cells seem to be in the
hippocampus. Memories are stored there for weeks or months and then, it
seems, moved elsewhere in the brain where they reside permanently. So,
Nottebohm said, it is possible that the hippocampus has "a space storage
crunch" that would cause it to run out of room for memories if it did
not kill off some cells and replace them with new ones.
The findings also raise the question of whether new brain cells grow
elsewhere in the brain and, if so, how to stimulate their growth when
the brain is injured or needs repairs. Scientists have argued that
evidence from stroke or trauma victims and people with degenerative
disorders like Alzheimer's disease indicates that once brain cells are
lost they cannot be replaced. But, Nottebohm said, the problem might be
that scar tissue is interfering with the reconnection of circuits in the
brain, not that new cells cannot grow. "We know that when scar tissue is
left behind, it interferes with the reconstitution of circuits" in the
brain, he said.
Gould said Alzheimer patients retain the immature cells that grow into
new hippocampus cells but lose the nerves that those cells would connect
to. The result is severe memory impairment.
The new work, Nottebohm said, "suggests that repair is a possibility."
And even though new brain cells have been found, so far, only in the
hippocampus, "it emboldens you to ask, Why not elsewhere?" he said.
"It is amazing," Nottebohm said.
Tuesday, March 17, 1998
Copyright 1998 The New York Times
Archive provided courtesy of WaveGuide, http://www.wave-guide.org
Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html