.. is trying to modify polypyrrole so that it will dissolve into the body and disappear as the nerve regenerates, like biodegradable sutures used in surgery. D. A recent study performed at Cornell University Medical College has demonstrated that exposure to magnetic fields can result in growth and regeneration of nerves. Dr.
Saxena, who was in charge of the research used low-level magnetic fields to trigger growth and regeneration of nerve sections in a culture medium (basically a petri dish). The study also found that those nerves that were not exposed to the magnetic fields experienced nerve degeneration. 1. Dr. Saxena said “At the end of the year, we found that included in the new growth was the myelin sheath, a structure responsible for normal nerve conduction of impulses.
These findings are especially important because the myelin sheath is the part of the nerve cell that actually conducts the electrical impulses.” E. Another means to restore nerve impulse traffic in both directions through the injured spinal cord is to allow these impulses to cross the regions on the nerve fibers that have been stripped of their insulation, or myelin. The electrical conduction of nerve impulses are blocked at these regions, and though the fiber may be intact, it is still “silent.” If nerve impulses do not decay in this damaged region, but are conducted to the other side, then they are carried through the rest of the nervous system in a normal fashion. The drug 4 aminopyridine (4 AP) can allow this to happen. The drug was administered by injection, and behavioral improvements could be observed sometimes within 15 minutes.
This break through was subsequently moved to limited human testing in two Canadian medical centers with colleagues Dr. Keith Hayes and Dr. Robert Hanseboiut. Their results extended the utility of 4 AP in human quadriplegic and paraplegics. 1. Richard B.
Bargains, Director for the Center of Paralysis Research who was present for the administration of the drug said, “I particularly remember one man, 5 years after his injury who began to breathe again more normally within hour of the administration of the drug.” Several more clinical trials of the drug have been completed in the US and Canada. F. MIT scientists and colleagues have recently discovered a gene that is capable of promoting nerve fiber regeneration. For the first time, they were able to fully reestablish lost connections in the mature brain of a mammal. Although the research was conducted on mice, they believe that it opens the door for the functional repair of brain and spinal cord damage in humans.
The scientists have shown that intrinsic genetic factors, not just the tissue environment, are of crucial importance. Brain tissue in adults contains factors that inhibit fiber growth and it lacks growth-promoting hormones. By culturing brain tissue, the scientists determined that genes that cause the growth of nerve fibers shut down at a very young age. G. Purdue University’s Center for Paralysis Research in conjunction with the School of Veterinary Science are using paraplegic dogs, with their owners consent, to test some new techniques of their own.
What researchers do is induce spinal nerve fiber regeneration and to some extent guide it, through the use of an applied electrical field. Very weak electrical fields are a natural part of embryonic development, particularly in the nervous system, and a inherent part of wound healing in animals. In experimental treatment for paraplegic dogs, researchers reverse the polarity of the applied electrical field imposed over the region of the injury every 15 minutes; using an electronic circuit which is implanted securely to the outside of the spine. H. In the US the use of fetal tissue is a very controversial subject-leading to a presidential ban on any use of human embryonic derived material.
Researchers at Purdue University have developed an alternative. They’ve shown that nerve cells removed from the gut and grafted to a spinal cord injury in the same animal can survive. Another interesting and potentially breakthrough technology involves the repair of individual nerve fibers using special chemicals that can both repair and cover holes in nerve membranes and even fuse the two segments of a cut nerve back togther. One may think of this as a molecular-chemical “band-aid” that prevents injured fibers from preceding on to separation and death. I. British scientists are developing a pioneering technique for reconnecting severed nerves.
But it will only work with peripheral nerves. Researchers at the Royal Free Hospital in London have found a way to persuade the severed ends of damaged nerves to grow though a special tube implanted to bridge the gap. The tiny tubes-a single millimeter in diameter are glued or stitched between the cut nerve ends. The inside of the tubing is coated with special cells, called Schwann cells, which release proteins that encouraged nerve growth. Once the nerve fibers have grown and reconnected the polymer tubing simply dissolves away. The Schwann cells would be grown from the patients’ own cells, taken from a tiny sample of nerve, to avoid rejection problems.
Doctors hope to begin implants into patients within a year. CONCLUSION: I. The three basic techniques that are currently being used to treat damaged nerves concern electrical, magnetic, and chemical stimulation. II. Rapid progress is being made in the area of research and treatment involving injured nerves. Within ten years, common place treatment will be available for what is presently deemed to be irreversible spinal cord damage. Bibliography Hibasami H., Hirata H., Morita A., Ohkaya S., Sasaki H., Uchida A.
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“Scientists rebuild’ damaged nerve tissue in mouse brain.” http://www.web.mit.edu/newsoffice/tt/1997/feb26/in dex.html (15 Feb. 2000) Mary Lenz. “Nerve regeneration project holds hope for injury victims.” http://www.che.utexas.edu/~schmidt/links/neuro.htm l (29 Sept. 1998). Richard B.
Borgens. “New Horizons in the Treatment of Spinal Cord Injury.” http://www.vet.purdue.edu/cpr/research.html#Electr ical Stimulation (4 Jan 2000). Thomas Brunshart, M.D. “New Strategies for Nerve Regeneration.” www.med.jhu.edu/ortho/news/ws1997/under.html (1997).