Human Testing Planned : Hormone May Prevent Paralysis After Injury

A synthetic hormone that has been shown to prevent paralysis in animals with spinal cord injury is being readied for trials on human patients, University of California officials said Thursday.

“If the human trial is as successful as the animal studies, we expect (the hormone) will prevent some of the paralytic effects of injury and keep people out of wheelchairs,” Dr. Alan I. Faden, a neurologist, said at a news conference held to announce the opening of the UC San Francisco Center for Neural Injury.

The National Research Institute for Neural Injury in Washington estimates that spinal cord injuries force an estimated 20,000 Americans into wheelchairs each year.

Although scientists believed until recently that paralysis inevitably followed damage to the brain or spinal cord, the consensus now is that such injuries need not necessarily lead to paralysis.

Clue Found in 1978 The about-face has resulted from research conducted in the last few years indicating that there may be ways--using drugs or transplanted nerve tissue, for example--to prevent serious consequences that once were thought inevitable.

A clue that paralysis caused by spinal cord injury may be prevented with drugs came in 1978, when Faden and Dr. John W. Holaday of the Walter Reed Army Institute of Research proposed that certain chemicals called endorphins released by the body in response to the injury may cause the damage that results in paralysis.

Endorphins, which are morphine-like substances, are the body’s natural painkillers.

Three years later Faden and his colleagues showed that they could reduce or prevent paralysis in animals by injecting naloxone, a drug that blocks the effects of endorphins.

The problem, however, was that naloxone sometimes also blocked the natural pain-relieving effect of endorphins.

Soon after, they found that another natural body substance-- thyrotropin-releasing hormone--worked as well as naloxone and allowed endorphins to allay pain.

The most recent results described on Thursday, which will be published in the journal Neurology, involve the use of a synthetic analog of thyrotropin-releasing hormone that remains at high concentrations in the blood for a longer period than the natural hormone.

This means, Faden said, that the newest drug could be administered at the scene of an accident, providing protection as quickly as possible that would last long enough to allow the patient time to be taken to a hospital for treatment.

In the great majority of spinal cord injuries, the spinal cord is not severed, Faden said. Therefore, he believes that if the hormone works as well on humans as it has on animals, paralysis could be prevented or minimized in a majority of spinal cord injuries if the drug is administered quickly enough.

Preventive Measure Faden said the hormone is intended to be a preventive and does nothing to restore function once paralysis has occurred.

He said that trials to test the safety of the hormone analog are being conducted at UC San Diego and that clinical trials on injured patients will begin within the next year at San Francisco General Hospital, the city’s major trauma center.

The new UC San Francisco center, to be situated at the Veterans Administration Medical Center in San Francisco, is a part of the newly established National Research Institute for Neural Injury, a not-for-profit corporation based in Washington.