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Saturday, October 23, 1999 Published at 01:01 GMT 02:01 UK


Key Alzheimer's protein found

Alzheimer's causes changes in the structure of the brain

Researchers have found a protein essential to the development of Alzheimer's disease.

They believe the discovery could pave the way for the development of drugs to treat the degenerative brain disease that are similar to those that have helped to combat the Aids virus.

The researchers, from California-based Amgen Inc and Harvard Medical School, say the protein, called BACE, stimulates other brain proteins to adopt a form that makes them damaging to the brain and causes Alzheimer's.

The disease starts with memory loss and progresses to profound dementia and death. There is no cure at present, although some drugs can slow the progression of the disease.

Alzheimer's patients have clots in their brains known as amyloid plaques and tangles of nerve cells.

A peptide, or protein fragment, known as amyloid beta peptide is believed to be key to the development of these plaques.

Critical role in the disease

Dr Martin Citron of Amgen, who led the research, said: "There has been overwhelming evidence over the last six years or so that the beta peptide that forms amyloid plaques plays an early and critical role in the disease."

This peptide is cut, or cleaved, off a larger protein known as amyloid precursor protein.

It was known that two special slicing proteins, known as proteases, did this. But no one could find them.

Now Dr Citron's team believe that they have identified BACE as one of these elusive proteases.

The researchers are now searching for a compound - a protease inhibitor - that can stop BACE from slicing up the amyloid precursor protein.

Protease inhibitors have been successfully used to keep HIV infection at manageable levels in thousands of patients.

But unlike the HIV protease inhibitors, one designed to work against Alzheimer's might work on its own.

"HIV is an infectious agent and it mutates at a very rapid pace whereas this one is not an infectious agent," Dr Citron said.

"There is a possibility that a protease inhibitor alone could do it. But only clinical trials could show that."

Dr Richard Harvey, director of research at the Alzheimer's Disease Society, said: "This research gives us a clue about new lines of investigation that could be followed potentially to develop new forms of treatment."

However, Dr Harvey warned that much more work was needed before any drugs could be developed.

He also stressed that preventing the formation of plaques in the brain would not necessarily prevent Alzheimer's as nobody was sure about the relationship between the plaques and the nerve tangles.

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