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Topic: Prion

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  Prion - Wikipedia, the free encyclopedia
Prions are abnormally-structured forms of a species-specific host cell surface protein, which are able to convert normal molecules of the protein into the abnormal structure.
Prusiner coined the word "prion" as a name for the infectious agent, by combining the first two syllables of the words "proteinaceous" and "infectious." While the infectious agent was named a prion, the specific protein that the prion was made of was named PrP, an abbreviation for "prion-related protein".
The prion hypothesis was highly controversial, because it seemed to contradict the so-called "central dogma of modern biology" that asserts all living organisms use nucleic acids to reproduce.
en.wikipedia.org /wiki/Prion   (1358 words)

 prion - Hutchinson encyclopedia article about prion
The existence of prions was postulated by US neurologist Stanley Prusiner in 1982, when he and his colleagues isolated a single infectious agent for scrapie that consisted only of protein and had no associated nucleic acid (RNA or DNA).
Prions have been found to consist of a simple protein called PrP, made up of about 250 amino acids, the gene for which is found normally in mammals, including humans.
Prion diseases have been found to arise both by transmission from other individuals (through, for example, diet or medical procedures) and by the inheritance of a mutation in the PrP gene.
encyclopedia.farlex.com /prion   (477 words)

 Prion (bird) - Wikipedia, the free encyclopedia
A prion is a petrel (genus Pachyptila) found in Antarctica and nearby islands.
Prions grow 20–27 cm long, and have blue-grey plumage with white underparts.
The Antarctic Prion and the Salvin's Prion are usually considered to be races of the Broad-billed Prion.
en.wikipedia.org /wiki/Prion_(bird)   (113 words)

 AllRefer.com - prion (Pathology) - Encyclopedia
The abnormal form differs in shape from the normal prions and is not susceptible to enzymes that normally break down proteins.
The gene that codes for prions can mutate and be passed on to the next generation; most of the diseases can be acquired directly by infection, but unlike other infectious agents, prions provoke no immune response.
The prion theory has been controversial from the beginning, and although scientific evidence for the existence of such infectious particles has increased, an exact causal link between prions and the diseases they are believed to cause remains to be established.
reference.allrefer.com /encyclopedia/P/prion.html   (516 words)

 BMBL Section VII-D - Agent Summary Statements /  Prions
molecule is accompanied by an alteration in the pathogenicity of the prion.
Prions are inactivated by 1N NaOH, 4.0 M guanidinium hydrochloride or isocyanate, sodium hypochlorite (2% free chlorine concentration), and steam autoclaving at 132C for 4.5 h.
Prusiner S.B. Prion diseases and the BSE crisis.
www.cdc.gov /od/ohs/biosfty/bmbl4/bmbl4s7d.htm   (3142 words)

 Prion Info - Encyclopedia WikiWhat.com   (Site not responding. Last check: 2007-10-21)
Prions are the hypothetical (and initially discounted) infectious agents consisting only of protein, with no nucleic acids.
However prions were discovered in the infected moss, which appeared to travel part way into the sides of the uninfected moss.
Prions have also been speculatively linked to cellular differentiation, the process by which stem cells take on specialized functions (such as muscle or blood cells).
www.wikiwhat.com /encyclopedia/p/pr/prion.html   (844 words)

 Prion finding offers insight into spontaneous protein diseases
After a year, the mice developed prion disease and brain tissue from the inoculated mice was injected into wild-type mice that subsequently developed prion disease in about half a year.
In contrast, prions are an aberrant form of a normal protein (thus composed of amino acids) that form when a particular segment of normal prion protein in the brain's nerve cells, or neurons, loses its corkscrew-shape structure (known as an alpha helix) and flattens into so-called beta sheets.
Once conversion occurs, they hypothesize, the prion moves on to other normal prion proteins, pinning and flattening their spirals, and thus, initiating a process that occurs repeatedly, akin to a deadly Virginia reel in the brain.
www.eurekalert.org /pub_releases/2004-07/uoc--pfo072704.php   (1425 words)

 Molecular Evolution of Prions
Prions are proteins that occur in the brains of all mammals so far studied.
The normal function of prion proteins is not understood, but recent research on mice that lack the PrP gene -- which encodes the prion protein -- suggest that it protects the brain against dementia and other degenerative problems associated with old age.
For example, a prion disease called 'kuru', found in the Fore tribe of New Guinea, is spread by ritual cannibalism, in which mourners eat the brains of their dead relatives.
www.mad-cow.org /~tom/prion_evol.html   (1694 words)

 Prion Diseases   (Site not responding. Last check: 2007-10-21)
Prion diseases are often called spongiform encephalopathies because of the post mortem appearance of the brain with large vacuoles in the cortex and cerebellum.
when prions are transmitted from one species to another disease develops only after a very long incubation period, if at all, but on serial passage in the new species the incubation time often decreases dramatically and then stabilises.
The prion hypothesis states that it is due to differences in the chemical or tertiary structure of the prion protein.
microbes.otago.ac.nz /micrzoo/Emerging/Prions.html   (2788 words)

 Pfam 19.0 : Prion   (Site not responding. Last check: 2007-10-21)
The prion protein is thought to be the infectious agent that causes transmissible spongiform encephalopathies, such as scrapie and BSE.
It is thought that the prion protein can exist in two different forms: one is the normal cellular protein, and the other is the infectious form which can change the normal prion protein into the infectious form.
Prion protein (PrP-c) PUBMED:2572197, PUBMED:1916104, PUBMED:2908696 is a small glycoprotein found in high quantity in the brain of animals infected with certain degenerative neurological diseases, such as sheep scrapie and bovine spongiform encephalopathy (BSE), and the human dementias Creutzfeldt-Jacob disease (CJD) and Gerstmann-Straussler syndrome (GSS).
pfam.wustl.edu /cgi-bin/getdesc?name=Prion   (765 words)

 Prion disease - Genetics Home Reference
Prion diseases are a group of progressive conditions that affect the brain and nervous system of humans and animals.
Mutations in the PRNP gene cause prion disease.
Familial forms of prion disease are inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
ghr.nlm.nih.gov /condition=priondisease   (694 words)

 Prion Page
These cases were extensively compared with other prion diseases and the lack of correlation seemed to confirm the arrival of a new strain of prion disease in the UK due to the incredibly small statistical probability of these similar cases occurring by chance.
The prion diseases themselves are known to be transmissible, from the early studies of Cuillé and Chelle, when they set out to determine the infectivity of scrapie in 1936, to the likely cannibalistic transmission of kuru.
The prion amyloid plaques are specific for prion diseases of animals and humans, and the deposition of the prion amyloid plaque is controlled at least partially by the prion protein sequence.
www.fortunecity.co.uk /roswell/psychic/24/prionpage/Project.htm   (15667 words)

 How Prions Work   (Site not responding. Last check: 2007-10-21)
The prions are proteins that are folded differently from that of normal proteins due to slight amino acid changes in certain regions of the protein (Figure 2).
Figure 2: The areas of human amino acid mutations that cause the abnormal folding of the prion protein are pictured using a hamster model.
When a prion causes an infection it causes other similar proteins to change their normal conformations to that of the abnormal form.
www.rit.edu /~sbib350/posters/prionwork.htm   (347 words)

 HHMI News: “Promiscuous Prion” Yields Clues to Infection Across Species Barriers
The ability of a single prion protein to fold into multiple infectious forms, say the scientists, means that knowledge of the shape of a prion, and not simply what species it came from, is critical to understanding which hosts it can infect.
The scientists conducted their studies using yeast prions, which are similar to the mammalian prions that have gained notoriety for their roles in such fatal brain-destroying human diseases such as Creutzfeldt-Jakob disease and kuru, and in the animal diseases BSE and scrapie.
Both yeast and mammalian prions are proteins that transmit their characteristics via protein-protein interactions in which an abnormally shaped prion protein influences its normal counterpart to assume an abnormal shape.
www.hhmi.org /news/weissman.html   (1048 words)

 US FDA/CFSAN Bad Bug Book - Prions and Transmissible Spongiform Encephalopathies
Prions are normal proteins of animal tissues that can misfold and become infectious: they are not cellular organisms or viruses.
When these proteins become abnormally shaped i.e., infectious prions, they are thought to come into contact with a normally shaped protein and transform that protein into the abnormally shaped prion.
All cases of vCJD to date have occurred in individuals of a single human genotype that is methionine homozygous at codon 129 of the prion protein.
vm.cfsan.fda.gov /~mow/prion.html   (1471 words)

 Kuru: The Dynamics of a Prion Disease
Understanding the structure and replication of the prion is crucial to interpreting the dynamics of kuru and several other prion diseases, which exist today.
The structure of a prion protein and its replication are fundamental to studying kuru.
Furthermore, the prion was inactivated by extreme treatments that destroy or denature proteins, such as chaotropic ions or denaturing detergents (Cashman, 1997).
www.as.ua.edu /ant/bindon/ant570/Papers/McGrath/McGrath.htm   (2908 words)

 New Scientist Breaking News - Synthesis marks prion disease breakthrough
When these synthetic prions were injected into the brains of mice, they triggered a prion disease that could be passed to other animals.
And rather than inject the synthetic prion into ordinary mice, the researchers used animals that were genetically modified to produce the same PrP fragment at a level 16 times higher than normal, making them more susceptible to prion infection.
But animals that received the synthetic prions started showing the wobbly gait, ungroomed fur and rigid tails that are the clinical signs of rodent prion disease after 380 days.
www.newscientist.com /article.ns?id=dn6219   (727 words)

 Prion Diseases   (Site not responding. Last check: 2007-10-21)
At the heart of this book lies a discussion of the still controversial idea that the infectious agent in prion diseases is a normal brain protein which takes on abnormal, mutant shape, the so-called "prion theory".
Susceptibility of a host to prion infection is co-determined by the prion inoculum and the PrP gene:
Collinge J. (2001) Prion diseases of humans and animals: their causes and molecular basis.
www-micro.msb.le.ac.uk /3035/prions.html   (3456 words)

 Mad Cow Disease pictures, prions, BSE, nvCJD images by Russell Kightley Media
Prions are implicated in BSE (Bovine Spongiform Encephalopathy or Mad Cow Disease) and its human counterpart nvCJD (new variant Creutzfeldt Jakob Disease).
Prions are pathogenic variants of proteins that are naturally produced in nerve cells and certain other cells.
The word "prion" stands for "proteinaceous infectious particle" and so should properly only be applied to the pathogenic variants.
www.rkm.com.au /BSE   (548 words)

 Homepage | CDC Prion Diseases
Prion diseases or transmissible spongiform encephalopathies (TSEs) are a family of rare progressive neurodegenerative disorders that affect both humans and animals.
A prion is an abnormal, transmissible agent that is able to induce abnormal folding of normal cellular prion proteins in the brain, leading to brain damage and the characteristics signs and symptoms of the disease.
Prion diseases are usually rapidly progressive and always fatal.
www.cdc.gov /ncidod/dvrd/prions   (324 words)

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