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Ottawa Team Finds Muscular Dystrophy Clue
Researchers are learning why some drugs slow destruction of muscle, then stop working.
By Tom Spears
The Ottawa Citizen
Ottawa Medical researchers have solved a 20-year-old mystery of why some drugs work - for a while - against muscular dystrophy.
Now, Lynn Megeney and Bernard Jasmin want to use this new understanding to find better drugs that children with the disease will be able to keep using after the current generation of drugs has lost its effectiveness.
Children with some types of muscular dystrophy today depend on a class of drugs called gluccortisoids - prenisone is the best know - which are used in a variety of diseases. People with asthma or arthritis, for instance, may take prednisone.
Some 20 years ago, doctors discovered that drugs derived from prednisone are useful in treating muscular dystrophy. But no one really knew how these worked.
Now they do.
Dr. Megeney, a molecular biologist at the Ottawa Heath Research Institute, traced how these steroid drugs counteract a destructive action of muscular dystrophy in which a host of protein molecules make muscle fibres deteriorate all over the body.
They don't shut off the destructive proteins, he said. But the drugs do counteract the damage, for a while.
Think of your body like a car, he suggests.
Its accelerator is stuck to the floor, and it's zooming down a very bad road that threatens to shake it apart.
"What these drugs do is, essentially, put the brakes on at the same time. The accelerator is still down, and the potential for further damage is still there. But as long as these drugs are there, they seem to put the brakes on … and stop the progression of the disease itself," he said.
But the drugs are only a temporary measure.
"It's still a fatal illness," he cautioned.
The drug loses its effectiveness after several years, but it remains the only effective drug for Duchenne's muscular dystrophy, a form of the disease that strikes one in 3,000 baby boys.
The drug lets children live longer, and lets them keep walking for three to five years after they would normally have to move to a wheelchair.
"Now what we can do, potentially, is either modify those existing drugs to reduce the side effects, or we can develop new drugs that are able to act on that same pathway…
"We are hoping that with this discovery, we can turn muscular dystrophy into a condition that is treatable, like Type 1 Diabetes."
The Megeney lab and Dr. Jasmin, of the University of Ottawa, hope now to design drugs with an muscle-preserving action similar to the current steroids.
Muscular dystrophy makes muscles deteriorate all over the body - the muscles that help us walk, stand, move our arms and breathe.
Some people hope to fight the disease through gene therapy, which works by inserting normal genes into cells with mutant versions; or with stem cells, which could some day allow the body to grow healthy new muscles. But these are still far in the future.
The Megeney-Jasmin team hopes drugs will be a faster route to treating muscular dystrophy.
The work is published in the Federation of American Societies for Experimental Biology Journal.
copyright The Ottawa Citizen