Nerve Regeneration Essay, Research Paper

Topic: New ways to aid in nerve regeneration. General Purpose: To inform

Specific Purpose: To inform the audience about news techniques and mechanisms

that aid in nerve regeneration. Central Idea Statement: The new techniques for

nerve regeneration involving magnetic, electrical, and chemical mechanisms look

very promising. INTRODUCTION I. The site is rather common: someone in a wheel

chair unable to use their lower body, or worse, unable to function from their

neck down because of an accident. You may even know one of these people. They

all have one thing in common: spinal nerve injury. To the majority of us, one of

the more famous and recent cases involving spinal trauma is that of Christopher

Reeve, known to most of us as Superman. Reeve was riding his horse when he fell

off, landed on the back of his head and twisted his neck. His spine was damaged

near the second cervical vertebrae; that being two vertebrae away from the base

of the skull. He states that after his accident he saw a handbook written in

1990 that "didn’t even mention anyone higher than [the fourth cervical

vertebrae] because 70 percent of them didn’t live longer than five days. I am

very lucky my injury happened at a time when treatment and surgery had

improved." Dr. Cotman from UCI, who worked with Reeve says that Reeve

remains optimistic that a cure is only a few million dollars away. II. Prior to

the end of the Second World War, if a person survived a severe spinal cord

injury, the injury still usually resulted in their early death. This was because

of complications that accompanied the injury, such as infections to the kidneys

and lungs. Though the development of new antibiotics has greatly improved life

expectancy, until recently medical science had not been able to restore nerve

function. III. According to researchers at the University of Alabama using data

from the regional SCI Centers, there are 7,800 traumatic spinal cord injuries

each year in the US. Yet these numbers do not represent accurate figures since

4,860 per year, die before reaching the hospital. Current estimates are that

250,000-400,000 individuals live with spinal cord injury or dysfunction;

forty-four percent of these occur in motor vehicle accidents. More than half of

these injuries occur to individuals who are single, and more than 80% of these

individuals are male. IV. Within the last five years, a great many things have

been happening in the area of neurological research. Research and treatment

involving spinal and nerve injury has progressed considerably. In this speech I

will inform you on the new and promising techniques that are currently

undergoing testing for human treatment, in terminology that we will be able to

understand. BODY I. The nervous system consists of the brain, spinal cord, and

all branching nerves. There are two parts: the central nervous system, or CNS,

and the peripheral nervous system, or PNS. The CNS, consists of the brain and

spinal cord, while the PNS involves all the nerves that branch off from the

spinal cord to the extremities. A. When the spine is crushed or bent in an

extreme accident, the spinal cord inside is severely bruised and compressed,

causing localized injury and death to many of the nerve cells and their fibers.

Some of injured nerves fibers survive intact, but lose their electrical

insulation, or myelin, over the very short distance of the injury zone. Nerve

impulses are blocked at this point. 1. The myelin is the part of the nerve that

actually transfers the electrical signal that enables your muscles to move when

you want them to move. B. Nerves regenerate at the rate of about a cm a month.

Keep in mind that not all nerves can regenerate (the spinal cord is a prime

example) and if a nerve is too damaged or is severed it cannot come back C.

Peripheral nerves will regenerate to a certain extent on their own, but they

don’t regenerate over very long distances. D. The big problem with treating

spinal injuries is the fact that mature nerve tissue does not spontaneously

regenerate. II. The three basic ways to treat nerve damage are: first, produce

regeneration of the remaining segment of a nerve fiber, or make new connections

on the other side of the injury. Second, prevent or rescue the damaged nerve

fiber from proceeding on to separation, or perhaps even functionally reunite the

two segments, so that both portions of the fiber survive. Or third, facilitate

nerve impulse traffic to cross the region of injury in intact fibers where they

have lost their electrical insulation. III. The techniques that are being used

to do this involve magnetic, electrical, chemical, or a combination of these to

stimulate the damaged nerve. A. At present surgeons take a nerve from a less

important part of the body and transfer it to the site of the injury. Generally

the nerve is taken from the lower leg, but then sensation is lost in that

portion of the body. Next, the surgeons attempt to repair the nerves by sewing

the proximal and distal ends of the nerves together. However, the results are

often disappointing. Even with the operation microscope, surgeons are unable to

precisely match the thousands of minute axons, each being approximately 1/100

the diameter of a human hair. B. Arthur Lander, a molecular neurobiologist who

came to UCI in 1999 from MIT, does research specifically on neural growth and

repair. What scientists currently want to learn, he said, is "the

fundamental mechanisms that control whether nerve fibers grow and where they

grow. It’s not good enough just to get them to grow, you’ve got to get them to

connect to the right targets." C. Dr. Schmidt, Ph.D. from the University of

Illinois further states, "Imagine the end of a damaged nerve as a small

child lost in a forest. The child is resilient and will seek a way out, but she

needs the help of a flashlight and a path." 1. Dr. Schmidt recently

received a grant from the Whitaker Foundation to research ways to use

electricity and an electrically conducting polymer material to stimulate nerve

cell growth. Dr. Christine Schmidt’s goal is to give the nervous system’s

natural healing mechanism the help it needs in repairing cells. This may mean

supplying a tiny burst of electricity to stimulate the growth of a damaged

nerve. It also means a pathway or tunnel the growing nerve can follow from the

site of the injury to its destination. The path or tunnel Schmidt is hoping will

help nerve growth is just that: a minute tube composed of a black-colored

material that somewhat resembles Teflon coating. Called polypyrrole, it is a

polymer that conducts electricity and can be filled with nutrients that help

nerves grow. The chief drawback at present is that polypyrrole is not

biodegradable. Schmidt 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.

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