Originally posted by loam

Here are a few new articles concerning prions:

Prions Rapidly 'Remodel' Good Protein Into Bad, Brown Study Shows

PROVIDENCE, R.I. — Two Brown Medical School biologists have figured out the fate of healthy protein when it comes in contact with the infectious prion form in yeast: The protein converts to the prion form, rendering it infectious. In an instant, good protein goes bad...

This quick-change “mating” maneuver sheds important light on the mysterious molecular machinery behind prions, infectious proteins that cause fatal brain ailments such as mad cow disease and scrapie in animals and, in rare cases, Creutzfeldt-Jacob disease and kuru in humans.

Because similar protein self-replication occurs in neurodegenerative diseases, the findings, published in the latest issue of Nature, may also help explain the progression of Alzheimer’s, Parkinson’s and Huntington’s diseases...

Satpute-Krishnan said the speed of protein conversion was surprising. “The prions were taking all the existing protein and refolding it immediately,” she said. “It’s a very, very rapid change...”

“Just a small amount of prion-state protein can rapidly convert healthy protein into a pathogenic form...”

And another...

NIAID Scientists Characterize the Most Infectious Prion Protein Particles

A new study of prions—apparently malformed proteins that initiate deadly brain diseases such as Creutzfeldt-Jakob disease in humans—has yielded surprising information about how the size of prions relates to their infectivity. Scientists have found that small prions are much more efficiently infectious than large ones, yet there also is a lower size limit, below which infectivity is lost.

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[edit on 11-9-2005 by loam]

U.S. probes possible mad cow case

The agency received an inconclusive test result on Friday, chief veterinary medical officer John Clifford said in a notice posted on the department's website on Saturday. ..."This inconclusive result does not mean we have found a new case of BSE," he said. And even if the animal does prove to have mad cow disease, he said, it didn't get into the human food chain or the animal feed chain. ...The USDA is following up with more detailed tests at a government lab in Ames, Iowa.

"The results of those tests will be released as soon as they have all been completed, within the next four to seven days," Clifford said.

***

U.S. mad cow case was Texas-born

The USDA says the cow was killed at a pet food plant after it was determined to be unfit for human consumption. ...Officials say the 12-year-old cow couldn't stand on its own feet.

U.S. investigators have found two previous cases of mad cow disease. The first was in December 2003 in a Canadian-born cow in Washington state. The second was last June in a cow that was born and raised in Texas.

***

A cow in Alabama has tested positive for mad cow disease, the Agriculture Department confirmed Monday, the third case in the U.S.
Alabama cow tests positive for mad cow disease

A method to extract and quantitatively detect prions from soil samples has been devised
by a team of scientists at two National Institute for Agricultural Research (INRA) labs in France
(Environ. Sci. Technol. 2006, 40, 1497).

The technique could be "a good starting point" to help identify and map prion-contaminated farmland
as well as to monitor the fate of prions over time...

INRA is looking at using the method for general environmental monitoring of prions
and possibly expanding the method for decontamination of medical devices.

Potential case of mad cow disease found in Manitoba

Dr. Wayne Lees, chief veterinary officer for Manitoba, said the animal, from the Interlake area, was born well before 1997, when Canada imposed a ban on the type of feed associated with BSE.

...Lees said the animal was showing signs of BSE — including difficulty walking. The owner had it euthanized and it was sent for inspection. ...Preliminary screening tests conducted by the provincial government and the Canadian Food Inspection Agency detected the potential case of BSE.

Alzheimer's deterioration may go unnoticed in some seniors

People can have the brain deterioration that comes with Alzheimer's disease without showing debilitating symptoms, a new study finds. ...Researchers in the U.S. studied the brains of 134 clergy who donated their bodies to science. They were in their 80s on average when they died.

None had clinical symptoms of Alzheimer's before they died, but 37 per cent showed lesions on the brain associated with the disease, a research team reported in Tuesday's issue of the journal Neurology.

"It means that a large number of people can accumulate all of this disease pathology and still be functioning very well," said study author Dr. David A. Bennett of the Rush Alzheimer's Disease Center in Chicago.