THE VIRGINIAN-PILOT
Copyright (c) 1995, Landmark Communications, Inc.
DATE: Friday, October 13, 1995 TAG: 9510130519
SECTION: FRONT PAGE: A1 EDITION: FINAL
SOURCE: BY MARIE JOYCE, STAFF WRITER
LENGTH: Long : 116 lines
Gordon C. Symonds was sitting in his living room the other night when he felt the sharp sting of a mosquito lancing his ankle.
It felt great.
For Symonds, who has been losing feeling in his extremities because of nerve damage brought on by diabetes, that little sting was a big event. It seemed to show that an experimental treatment can do something doctors have been pursuing for years - re-grow nerve cells.
Symonds is a patient at The Diabetes Institutes at Eastern Virginia Medical School, where researchers are participating in a national study of an experimental drug. The studies are being paid for by the drug's manufacturer, Genentech, based in California.
It's possible the drug might even be useful for types of peripheral nerve damage caused by other illnesses and injury. But even if everything goes well - if the substance is found to be helpful without hurting patients - it will be years before people with diabetes can expect to get prescriptions for the medication, said Dr. Aaron I. Vinik, director of the Diabetes Research Institute.
The drug, nerve growth factor, is still in early stages of tests on humans.
But just three months after his first injection, Symonds is an eager advertiser. He had been dropping weight quickly - nerve damage had messed up his digestive system and killed his appetite.
``I've got hunger like you won't believe back now,'' said the Virginia Beach businessman, who recently reveled in the sensation of walking on the sand in his bare feet, something he hadn't done in years.
Why diabetes kills nerve cells isn't completely understood. In part, it may be because glucose - blood sugar - attaches itself to proteins on the membranes that cover nerve cells. The body's immune system no longer recognizes these cells and attacks them, destroying the membranes. Because the membranes help speed along messages passing through nerve cells, the nerves don't work as well.
It may be that the immune system also attacks the nerves themselves. The disease also affects the production of nerve growth factor, the substance that is being tested at the Diabetes Institutes. For decades, scientist have known of nerve growth factor, a hormone that spurs the growth of nerve cells in the fetus.
But only recently have they realized that the substance seems to be present throughout life, protecting the integrity of nerves.
And it's only recently that recombinant technology has existed to allow companies to manufacture a significant amount of the substance to use in treatment. The technology has drug companies like Genentech scrambling to develop substances that will revive nerve cells.
Nerve damage doesn't occur in all people with diabetes.
Some people find they are able to slow the nerve damage through very tight control of blood sugar. But that doesn't work in all cases, and Vinik believes that recent studies have overstated how much nerve damage can be controlled.
For those who do suffer the neuropathy, the consequences are serious. Symonds recalls the excruciating pain as his nerves died. It was so bad that he couldn't sleep well. It felt like a toothache in his foot.
``For five solid months, I was walking on toothaches,'' he said.
After that, there's constant danger. People injure themselves easily, because they don't know when they're doing something wrong.
``Pain is a warning signal your body gives you,'' said Vinik.
Foot injuries are common. Normally, people are constantly, unconsciously adjusting the position of their feet as they walk or run, responding to sensory signals sent when different pressure points are pressed. People with nerve damage tend to slap their feet down the same way each time. Sometimes, they destroy bones. Or the tissue damage can lead to ulcers, gangrene and even amputations.
Nerve death can damage the digestive system, by making it hard to swallow, by deadening the nerves that stimulate muscles to carry food through the esophagus, or by preventing the bowels from working right.
It can cause heart trouble - the heart doesn't respond by speeding up at times of exertion. Or a patient may not feel the pain that's warning of a heart attack.
The condition is so far considered irreversible. Unlike some other types of tissue, nerve cells either don't grow back at all, or re-grow so slowly that they can't offset the damage of diabetes.
Nerve cells proliferate in the fetus before birth and during the first three weeks or so of life. After that, ``The body says, `No, you've got your complement.' '' says Vinik.
EVMS is one of six centers across the United States participating in the trial. It's in the first phase of human trials, which means doctors still are trying to see if it works in people and how bad the side effects may be.
And it does have a bite. For one thing, diabetes patients may have grown accustomed to painlessness. The return of burning, stabbing and other sensations isn't welcome. ``Some people say, `I was better off before,' '' said Vinik.
And the rejuvenation comes with some pain of its own. When the nerves grow, they send random electrical signals that the brain interprets as pain. The spurts of pain don't last long, said Symonds, who would experience about five minutes of sensation shooting from his knee to his toe. However, doctors don't really have a good idea how long the condition will continue - that's one of the questions under study. Scientists believe it takes about 18 months for a full recovery.
``We're seeing if it works at all,'' says Vinik.
And even if it does work, it may not solve all nerve problems caused by diabetes. This growth factor clearly works on nerves that control sensation and involuntary responses, like digestion. It's not clear that it restores nerves controlling muscle movement, so it may not overcome muscle weakness. ILLUSTRATION: Graphic
KRT
EYE CHIP MAY RESTORE SIGHT
SOURCES: Harvard Medical School; KRT research.
[For complete graphic, please see microfilm]
TO PARTICIPATE
Anyone interested in participating in the nerve growth study can
contact the Diabetes Research Institute at 446-5912.
KEYWORDS: DISEASES DIABETES TREATMENT by CNB