Molecular decoy thwarts Alzheimer's.

As a novel strategy to slow the progression of symptoms, researchers have designed polymer molecules that block the activity of proteins associated with Alzheimer's disease.

These beta-amyloid proteins accumulate in the brains of people with Alzheimer's The substance's toxicity triggers brain-cell death. Previous studies have found that beta-amyloid attacks brain cells by attaching to sialic acid molecules that are abundant on the cells' surfaces.

The researchers decided to create molecular decoy that would steer beta-amyloid away from cells. Theresa Good of the University of Maryland, Baltimore County and her colleagues used star-shaped polymers called dendrimers and decorated their tips with sialic acid molecules.

In preliminary tests, the researcher, added the polymer decoys to a laboratory dish containing beta-amyloid and nerve cells. The proteins selectively bound to the decoys, leaving the cells unscathed.

Injecting the polymers into a person', blood might draw beta-amyloid out of the brain, says Good. There is some evidence that that the toxic proteins move freely between the brain and the blood.

If that approach proves ineffective, the scientists plan to engineer the polymers so that they can cross from the blood into the brain, where they would divert beta-amyloid from attacking cells. --A.G.