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Prions

ELKCHSR

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Nov 28, 2001
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There is headway being made into these little nasties, maybe some day soon they will come up with an answer on how to deal with them

NIH Finds Clue to What Makes Prions Kill By LAURAN NEERGAARD, AP Medical Writer

http://news.yahoo.com/news?tmpl=story&cid=1894&e=4&u=/ap/20050603/ap_on_sc/prion_clue

WASHINGTON - Government scientists have found an important clue to how rogue proteins that cause mad cow disease and its cousins destroy the brain: These mysterious substances must latch on to the outside of cell membranes to be toxic.


If scientists could break the fatty Velcro-like bond that anchors these so-called prions, they might devise a treatment for the deadly illnesses, suggests research published in Friday's edition of the journal Science.

"We need to focus on that as a target for drug therapy," said the lead researcher, Dr. Bruce Chesebro, a virologist at the National Institutes of Health's Rocky Mountain Laboratories. "Clues are really hard to come by" in prion diseases.

Related diseases — including mad cow, scrapie in sheep and the human Creutzfeldt-Jakob disease — are believed to arise when a protein the body normally harbors folds into an abnormal shape, called a prion, and sets off a chain reaction of misfolds.

When enough abnormal prions accumulate, they deposit plaque on the brain and eventually leave clumps of dead brain cells. Those are the diseases' hallmark spongy holes.

But scientists don't understand exactly what makes these rogue prions poisonous to brain cells.

To study how prions function, Chesebro and colleagues genetically engineered mice that lacked the fatty anchor that usually binds prions to the surface of cells. Then the scientists injected the transgenic mice and regular mice with scrapie-causing prions.

All 70 of the regular mice promptly got sick.

But the 128 specially bred mice showed no symptoms of scrapie even though Chesebro watched for up to 600 days. That is far longer than it should take illness to appear.

Under a microscope, their brains show lots of the telltale plaques. But their brain cells had not died.

"We were really surprised," Chesebro said.

He is continuing to track some of the mice for signs of more subtle damage than scrapie usually causes, such as memory loss.

If the abnormal prions are not bound to cells' surfaces, they may be unable to disrupt signaling between cells — a leading theory behind their toxicity, said neuropathologist Adriano Aguzzi of the University Hospital of Zurich, Switzerland, in an accompanying editorial.

The work provides "a tantalizing inroad," he said.
 
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