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Rogue proteins and mad cow disease

A study published in the July 30th, 2004 issue of Science magazine reveals that mad cow and similar brain diseases can be caused by proteins alone. For a number of years, scientists have theorized that misshapen proteins or "prions," are the underlying cause of mad cow disease. Now there is compelling proof. This finding overturns the long-held notion that only bacteria and viruses transmit disease.

To test the prion theory, Researchers at University of California at San Francisco created a protein that was folded into an abnormal pattern. They injected this misshapen protein into the brains of lab mice. Over time, the mice developed a disease very much like mad cow disease. When tissue from these infected mice was then injected into healthy mice, they, too, developed the disease.

How can a misshapen protein spread disease? For reasons not yet known, healthy proteins in the vicinity of a prion reshape themselves into replicas of the rogue protein. (Think of a prion as a rowdy child who gets an entire classroom of children to misbehave.) Soon there are millions of defective proteins in the brain, disrupting brain function and creating a characteristic spongy appearance. After a period of time, a person or animal infected with prions begins to behave abnormally and dies a premature death.

The leader of the study was Dr. Stanley Pruisner who received the 1997 Nobel Prize for his work on prions. An article about the study appears in the July 30th, 2004 edition of The New York Times.

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