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Case Western BSE Study

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Mike

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Just an article for those that question whether beef causes vCJD. Read carefully, this is the foremost school in the world for prion research.
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New study shows how Mad Cow prions hitch a ride into intestine
They piggyback on iron-storing proteins after surviving digestive juices
December 28, 2004 | For more information: George Stamatis 216-368-3635

A new study from the Department of Pathology at Case Western Reserve University School of Medicine shows that the infectious version of prion proteins, the main culprits behind the human form of mad cow disease or variant Creutzfeldt-Jakob Disease (vCJD), are not destroyed by digestive enzymes found in the stomach. Furthermore, the study finds that the infectious prion proteins, also known as prions, cross the normally stringent intestinal barrier by riding piggyback on ferritin, a protein normally absorbed by the intestine and abundantly present in a typical meat dish. The study appears in the Dec. 15 issue of the Journal of Neuroscience.

Prions are a modified form of normal proteins, the prion proteins, which become infectious and accumulate in the nervous system causing fatal neurodegenerative disease. Variant CJD results from eating contaminated beef products from cattle infected with mad cow disease. To date, 155 cases of confirmed and probable vCJD in the world have been reported, and it is unclear how many others are carrying the infection.

According to the study’s senior author Neena Singh, M.D., Ph.D., associate professor of pathology, little is known about the mechanism by which prions cross the human intestinal barrier, which can be a particularly difficult obstacle to cross.

“The mad cow epidemic is far from over, and the continuous spread of a similar prion disease in the deer and elk population in the U.S. raises serious public health concerns,” said Singh. “It is therefore essential to understand how this disease is transmitted from one species to another, especially in the case of humans where the infectious prions survive through stages of cooking and digestion.”

Using brain tissues infected with the spontaneously occurring version of CJD which is also caused by prions, the researchers simulated the human digestive process by subjecting the tissue to sequential treatment with digestive fluids as found in the human intestinal tract. They then studied how the surviving prions are absorbed by the intestine using a cell model. The prions were linked with ferritin, a cellular protein that normally binds excess cellular iron to store it in a soluble, non-toxic form within the cell.

“Since ferritin shares considerable similarity between species, it may facilitate the uptake of prions from distant species by the human intestine,” said Singh. “This important finding provides insight into the cellular mechanisms by which infectious prions ingested with contaminated food cross the species barrier, and provides the possibility of devising practical methods for blocking its uptake,” she said. “If we can develop a method of blocking the binding of prions to ferritin, we may be able to prevent animals from getting this disease through feed, and stop the transmission to humans.”

Currently, Singh’s group is checking whether prions from distant species such as deer and elk can cross the human intestinal barrier.

The study was supported by National Institutes of Health grants.

Link for proof of authenticity:

http://www.case.edu/news/2004/12-04/madcow.htm
 

Mike

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Quote by SH to Reader:"Like everyone else here, I sympahize with your loss but that doesn't give you the right to suggest that eating beef leads to vCJD WITHOUT PROOF.

You have no proof that vCJD is caused by eating beef yet that is what you have instilled into your kids.

If you want to error on the side of caution, with your kids, after the loss of your husband that's your business but that doesn't give you a free pass to speculate on the safety of our product here.

Go ahead, call me insensitive and uncaring during your loss because you can't handle the truth which is that there is no proof that vCJD is caused by eating beef."
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Prions are a modified form of normal proteins, the prion proteins, which become infectious and accumulate in the nervous system causing fatal neurodegenerative disease. Variant CJD results from eating contaminated beef products from cattle infected with mad cow disease. To date, 155 cases of confirmed and probable vCJD in the world have been reported, and it is unclear how many others are carrying the infection.
 

Mike

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Neurobiology of Disease
Protease-Resistant Human Prion Protein and Ferritin Are Cotransported across Caco-2 Epithelial Cells: Implications for Species Barrier in Prion Uptake from the Intestine

Ravi Shankar Mishra, * Subhabrata Basu, * Yaping Gu, Xiu Luo, Wen-Quan Zou, Richa Mishra, Ruliang Li, Shu G. Chen, Pierluigi Gambetti, Hisashi Fujioka, and Neena Singh

Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106


Foodborne transmission of bovine spongiform encephalopathy (BSE) to humans as variant Creutzfeldt-Jakob disease (CJD) has affected over 100 individuals, and probably millions of others have been exposed to BSE-contaminated food substances. Despite these obvious public health concerns, surprisingly little is known about the mechanism by which PrP-scrapie (PrPSc), the most reliable surrogate marker of infection in BSE-contaminated food, crosses the human intestinal epithelial cell barrier. Here we show that digestive enzyme (DE) treatment of sporadic CJD brain homogenate generates a C-terminal fragment similar to the proteinase K-resistant PrPSc core of 27-30 kDa implicated in prion disease transmission and pathogenesis. Notably, DE treatment results in a PrPSc-protein complex that is avidly transcytosed in vesicular structures across an in vitro model of the human intestinal epithelial cell barrier, regardless of the amount of endogenous PrPC expression. Unexpectedly, PrPSc is cotransported with ferritin, a prominent component of the DE-treated PrPSc-protein complex. The transport of PrPSc-ferritin is sensitive to low temperature, brefeldin-A, and nocodazole treatment and is inhibited by excess free ferritin, implicating a receptor- or transporter-mediated pathway. Because ferritin shares considerable homology across species, these data suggest that PrPSc-associated proteins, in particular ferritin, may facilitate PrPSc uptake in the intestine from distant species, leading to a carrier state in humans.


Key words: prion infection; subclinical infection; PrP transport; new variant CJD; ferritin; epithelial cell barrier; Caco
 

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