Please, please, please keep the good work...
Jim Andrews Phoenix
At 12:38 PM 4/5/99 -0400, you wrote:
>Method To Repair Nerve Fibre Offers Hope For Future Treatment
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>WASHINGTON, DC -- April 1, 1999 -- Scientists have found success in animals
>with a promising new way to rejoin severed nerves quickly.
>
>"The technique rejoins the cut or crushed ends of severed central and
>peripheral nerve cells so that the repaired cells again conduct electrical
>signals through the severed area within seconds to minutes after they are
>rejoined," said George Bittner, Ph.D., of the University of Texas at Austin.
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>The central nervous system (CNS) includes the brain and spinal cord. The
>peripheral nervous system (PNS) includes nerves found in the rest of the
>body.
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>Several hundred thousand central and peripheral nervous system injuries
>occur annually in the United States, primarily due to trauma and stroke.
>There is currently no technique in humans or other mammals which can repair
>severed nerves in the brain or spinal cord or speed up the repair of severed
>peripheral nerves.
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>"The technique opens up a completely novel approach to restoring
>physiological continuity in the injured nervous system," explained Michael
>Selzer, M.D., Ph.D., a neurologist at the University of Pennsylvania.
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>Bittner's study is published in today's issue of The Journal of
>Neuroscience.
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>Nerve cells possess axons, extensions that transmit electrical signals over
>long distances in the body. When these biological transmission lines are
>cut, their electrical signals can no longer be transmitted. Nerve cells in
>mammals, including humans, usually cannot regenerate axons that are severed
>in the CNS. At present, the functions once controlled by those axons cannot
>be restored. Severed PNS axons regenerate very slowly, about one millimetre
>per day.
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>In the new study, Bittner and his colleagues applied a calcium-free solution
>of polyethylene glycol (PEG) for one to two minutes to the cut ends of
>severed axons. PEG causes the cell membranes of closely approximated cells
>to fuse. The researchers then washed off the PEG solution and bathed the
>site where the axons had been joined in calcium solutions that mimic the
>salt composition of mammalian body fluids. They found that within two to 30
>minutes many of the once-severed axons regained their ability to transmit
>electrical impulses through the lesion site. They then applied a biological
>adhesive (a PEG-hydrogel) developed by one of the authors, Jeffery Hubbell,
>Ph.D., who is now at the Swiss Federal Institute in Zurich, Switzerland.
>This substance binds very tightly to the severed axons and prevents the
>rejoined axons from pulling apart once the animal recovers from anesthesia.
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>The researchers have now successfully used this technique to rejoin the
>severed halves of CNS and PNS axons from crayfish, earthworms, rats,
>rabbits, and guinea pigs.
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>"This new approach can almost certainly be used to rapidly rejoin cut or
>crushed axons in humans," Bittner said.
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>To aid this effort, Bittner and his colleagues have already published papers
>showing how the severed ends of mammalian axons can be kept alive for at
>least days after they are disconnected from their parent cells. An ability
>to keep severed axons alive would give surgeons a longer time to rejoin
>those axons with PEG solutions.
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>Selzer said that, until now, demonstrations that fused mammalian nerve
>fibres can conduct electrical impulses have been performed in tissue
>isolated from the body. Among crucial questions that remain are whether the
>technique can fuse axons in a living mammal and whether this approach can
>result in recovery of useful function.
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