Talk:Prion/Archive 1

Setting the record straight

I write this to whoever set up this wikipedia page on prions and whoever has been making comments about my appearance on it. I am astounded that people can write as factual material that which has only appeared in the media to hype up particular stories. My "association" with Mark Purdey was largely created by the media. That what is known about my research is largely presented here as misquotations of those media articles is really not appropriate. If Nature only found seven errors in this article they were not looking very hard because frankly, the whole thing should be deleted.

I have deleted the racist comments directed at me by someone who edited these pages. I note that wikipedia has banned them from editing pages here any further which is a good thing. For those who want to know where I work then see this page:

http://www.bath.ac.uk/bio-sci/research/profiles/brown-d.html

In terms of the science, I believe that my contribution (whether it is worth mentioning on wikipedia or not) is to show that this protein is a metal binding protein and the identification of the function of the prion protein. None of this is "speculation". As it currently stands the section on manganese is utterly misleading as it does not correctly state Mark Purdey's theories or provide any real insight into my own (unrelated) work. Some of that work has been publish some time after Mark's untimely death.

I have NEVER at any time believe manganese to be the cause of prion disease. My statements to the BSE enquirey almost ten years ago were in relation to both my work and the possible role of manganese as a risk factor. In this regard "heavy metal poisoning hypothesis" belongs solely to Mark Purdey.

Professor David R. Brown —Preceding unsigned comment added by 138.38.27.69 (talk) 13:56, 16 February 2009 (UTC)

Reply to David Brown

Hi and welcome. I used to edit this page but long ago got tired of the spamming! I used to work in prion research, though several years ago so the debate has probably moved on. I'll try to help keep a closer eye on it. No offence was intended by my "speculative" comment below. Purple 21:47, 23 March 2009 (UTC)

Grossman's Misquote:

Complex problems have simple, easy to understand wrong answers.

It would be so nice if the professor would provide us with a synopsis of his textbook. So far, there are three theories, and I happen to think that they must all be wrong on some point. 216.234.170.67 (talk) 17:39, 16 July 2009 (UTC)

Once again I checked this article and found further slurs against Professor Brown by the same contributor. I have deleted them again. I advise the contributor to actually read the statement made by Brown to the BSE Enquiry. http://www.bseinquiry.gov.uk/files/ws/s638.pdf The main page as is still needs correction in terms of presenting the theories regarding manganese.--Gonkstem (talk) 21:05, 22 July 2009 (UTC)

"Oxford Professor" ... nope, but professor nonetheless.

Brown isn't at Oxford. He taught my neurobiology unit at Bath, where he's still listed on the faculty page. 90.196.219.11 18:46, 3 October 2007 (UTC)

Starting at trying to end the article with an opinion about genetics, I'm considering reverting this article back several months and snipping that attempt at a summary. There are three positions in the debate, and they all contain one word. BrewJay (talk) 09:00, 10 June 2008 (UTC)

These pages are for commenting on science - not on slurring people's names and making inappropriate comments on their professional standing. There is one particular contributor who continues his tirade against Professor Brown and if it does not stop I will report you! I have deleted your more recent comments (including your very poor English) --Gonkstem (talk) 22:31, 20 July 2009 (UTC)

The first paragraph is currently plain wrong

I am not an expert, but the article does not make sense. The truth is the "badly folded form" propogates by causing other forms to refold. But if the badly folded forms are called prions, and also the other forms are called prions, then the paragraph is inaccurate as now worded.

I'll try to figure out what you want, but you gleaned the truth from what was said. The old version of the article had a lot of unpronouncable superscripts that my grammar checker doesn't understand, whereas I've tried to clearly identify the protein as either diseased or normal wherever that wasn't clear from the context (in some cases, I think I used flat or twisted). Only once, if I remember correctly, was it necessary to introduce terms that you would find in print for the initiated.

Brewhaha@edmc.net 11:10, 8 May 2007 (UTC)

i have re-worded a bit of the 1st paragraph, which should clarify the difference between PrP^C and PrP^SC, as the prion protein is found in mammalian tissue - it is only after exposure to the misfolded form that the disease is induced.

Jesse.maegan (talk) 01:32, 20 September 2008 (UTC)

Exotic Ungulates

Can anyone state a good reason to separate one kind of hoofed animal from another? Brewhaha@edmc.net 09:18, 30 November 2006 (UTC) The section on exotic ungulates is currently red, because it's not in the wiki. Brewhaha@edmc.net 09:18, 30 November 2006 (UTC)

It is well-known that zoologists classify ungulates according to whether they have an odd-number of toes on each foot (e.g. the horse) or an even-number of toes on each (e.g. the bovine or the camel). Why do they do this? You'd have to find one and ask one! DAW - a mathematician! —Preceding unsigned comment added by 74.249.82.139 (talk) 04:20, 17 March 2008 (UTC)

Dissent deletion

should the section

"(This isn't dissent per se. It's merely an alternative model for the initial acquisition of Prion related diseases. Its relevance and specificity to bovines is questionable and possible it is more relevant to murine disease acquisition. How it relates to the BSE epidemic is hard to fathom, it certainly may play a role in disease acquisition, however, the plague like transmission is overwhelmingly attributed to the consumption of infectious material. To title this section dissent is kind of baffling as there are many other occurrences which result in the initial incidence of the disease, but none of these account of the aformentioned epidemic. Furthermore, the models which do explain PrP formation biochemical models are just that, biochemical models, proven in a laboratory. They certainly are not epidemiological studies used to build models in the absence of experimental work.)"

even be in the article? it reads more like a forum post replying to the previous paragraph than something that belongs in wikipedia-Lehk 05:23, 8 September 2006 (UTC)

[1] I tend to think not. It is like a forum post, as you say, but more agreeable than most I've dealt with. Whoever wrote it is trying to find a way to the touted neutral point of view. Brewhaha@edmc.net 09:18, 30 November 2006 (UTC)

I don't see the point of this section either - Purdy and Brown have not "dissented" to the existence of prions, they've just expressed some different ideas about the role of metal-binding. There is no controversy over whether PrP binds metal cations or whether these can somewhat influence PrP structure. David Brown places a lot of emphasis on his proposal that metal binding gives PrP enzyme activity and that abnormal binding might lead to a disease state, while Mark Purdy, who was a farmer by profession, was interested in differences in metal ions in the soil and a possible relevance to BSE. Brown was the only established prion researcher who took Purdy's ideas seriously, while Brown's ideas are interesting but have not quite become 'mainstream' and are still mostly considered speculative. I don't really see why these two interesting but minority views warrant a section to themselves. Purple 12:32, 3 January 2007 (UTC)

The question is not a popularity contest. I moved the section that referred to "protein-X" before I saw this comment, and I hope you can see that it fits into dissent. I read of other causes for dissent in a Nature article. Perhaps I left a reference to it on the talk page about TSEs. As for the FAQ format? I think that should sit for a while. Brewhaha@edmc.net 15:43, 20 February 2007 (UTC)

Division of Topics

-- FFI is more relevant to TSEs. Brewhaha@edmc.net 09:18, 30 November 2006 (UTC)

Fatal Familial Insomnia is genetic. But it is inherited as a one base mutation on the same gene that synthesises PrP, the prion protein. I do not know if attempts to infect organisms with FFI have been successful.

In FFI patients, PrPSc is often not detectable in the brain, yet the disease is transmissible (Tateishi et al., 1995;Collinge et al., 1995) Pikzee 18:04, 21 March 2007 (UTC)

I must also add that a lot of information on prion actionmechanism is speculative. The evidence of prions being infective agents is not yet conclusive. The final "proof" will be infectivity initiated by injection of synthetically produced prion material into an organism. This would be the only way to ensure that no other agents have been introduced. A vocal scientific minority still opposes this.

I think therefore that this article needs a rewrite to take into account these issues. Also a list of references will be useful. I am not competent enough to do this due to lack of biology knowledge. I will add a few external links with more info.--Viz

It seems that an artificaial prion HAS been created:

http://www.nature.com/news/2004/040726/full/040726-11.html

Stability of Vector

What puzzles me is how prions can survive extreme conditions (e.g. autoclaving) that clearly are capable of denaturing proteins. This suggests that something is missing in our understanding of this phenomenon. Beyond that, there are certainly many factors that will influence the folding of proteins. It would seem possible, likely even, that many proteins have alternative folding configurations, and that many non-fatal and less obvious diseases (less obvious compared to CJD) may have their basis in problematic protein folding. --BL

Denaturation is essentially a type of refolding. Other proteins are difficult to heat denature as well--especially short ones. Dogface 05:01, 6 Apr 2004 (UTC)

The beginning of paragraph two mentions "mysterious infectious agents" and then has these agents in the singular; visiting the Creutzfeldt-Jakob Disease revision history shows that this part did indeed refer specifically to the prions causing C-JD so I've clarified it as such here. --KQ

Isn't fatal familial insomnia genetic? --LDC

Spelling of Deutschenamen

is it really Creutzfeldt? I thought it was spelt with a "K"

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All of the references I checked spell the names as "Hans Gerhard Creutzfeldt" and "Alfons Maria Jakob". Both are German, and I agree that the initial-C looks odd for a German name, and "Creutz" is not a German word I'm familiar with. Maybe he has a different ancestry or something.

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It is Creutzfeldt, from "Kreuz" meaning cross and "Feld" meaning field. As you noticed, the spelling is not correct in today's German, but that is not unusual in names, as they often date back some centuries. Also, "Maria" isn't a usual name for boys these days anymore (except Klaus-Maria Brandauer). --Magnus Manske

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There are exceptional names & words in German that start with "C" rather than with "K". Here are some examples: the city of Chemnitz - that the East Germans called Karl Marx Stadt, but which has been reverted to its old name (just like St. Petersburg has). "Chemie" is the German word for chemistry. "Computer" is very-widely used in German now, even though it is clear that it was adopted from English. The old, old obsolete word was "Rechnenautomat". Look at any good German-English dictionary for lots more examples. At the beginning of words, I have been told that the Germans especially dislike the "kh" combination (too Slavic, as in Khruschev) and they use "ch" instead. Lots of people who live in modern Germany had ancestors who lived in places like Czechoslovakia, Romania, Hungary, Switzerland, Poland, etc., long ago, so there IS some variation due to that.

Wiki technique

Somebody turned this page into a disambiguation page and then didn't bother to fix any links to point to the new pages (per our disambiguation guidelines). So I moved this page back to fix the links and added a disambiguation block to the top of this page. --mav

Welcome to Wikipedia! We welcome your help to create new content, but your recent additions (such as Prion/Comments) are considered nonsense. Please refrain from creating nonsense articles. If you want to test things out, edit the sandbox instead. Take a look at the welcome page if you would like to learn more about contributing to our encyclopedia. Seinfreak37 17:24, 20 February 2007 (UTC)

I think you'd better double-check that. You can find the word "here" at the top of this page where it tells you where to write why you might want to rate a page good. Brewhaha@edmc.net 15:15, 22 February 2007 (UTC)

Ist es logish?

If N and P were really made by fork of a normal metabolic pathway, and P would cause negative feedback on N in this process, every organism would quickly infect itself without external P's; it would be sufficient to produce some P's "normally".

More on Vector Stability

The pathogen thought responsible for this disease is not a virus, not a fungus, not a bacteria, but thought to be a prion — an infectious protein. Because of their unique structure, prions are practically invulnerable. They can remain infectious for years in the soil. They are not adequately destroyed by cooking, canning, freezing, usable doses of radiation, digestive enzymes or stomach acid. Even heat sterilization, household bleach and formaldehyde sterilization have little or no effect. One study raised the disturbing question of whether even incineration could guarantee the inactivation of prions.

That study was performed by Paul Brown, medical director for the U.S. Public Health Service, who found prions could remain infectious even after exposure to temperatures over 1000 degrees Fahrenheit ( = 538 degrees celcius). That's hot enough to melt lead. Prions have been called the smallest, most lethal biological entities in the world. [2]

I think you should take a look at this study's abstract: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14697205

I don't see anything about autoclaveing in that abstract. The washington times doesn't provide links to old editorials. I read someone who had done the experiment or at least studied it about ten years ago among the customer opinions, so I'm led to believe that it's very old news. I'm curious to know how old. Brewhaha@edmc.net 15:06, 12 August 2007 (UTC)

Info about 1000 degrees and bleach is wrong. The above reference is either obsolete (potentially a common Wikipedia problem with evolving science) or misleading for those who don't understand the context. CDC procedures clearly state that prions can be safely destroyed by proper autoclaving. The problem being that many medical autoclaves are too cheap to reach the proper temperature in the first place or are out of calibration. http://www.cdc.gov/od/ohs/biosfty/bmbl4/bmbl4s7d.htm (inactivation of Prions) Correctly autoclaving at 132C degrees for 4.5 hours is one way to safely destroy one common type of infectious prions. If I remember correctly, one alternative is autoclaving with a 5% bleach solution at 160 degrees for 45 minutes. But if you do autopsies with possible prion involvement I'd find the latest CDC reference. I seem to remember that there was also bleach combo solution for general clean up of surfaces not expected to have potential invasive contact with human tissue (e.g. floors versus scalpels). But it is true prions are not known to be biogradeable in common natural settings.

If I remember correctly the 1000 degree and other invulnerability legends came from very early data about prions. Some of the early research was assisted by concerned UK country doctors. Unfortunately some of UK general practioners basically didn't know what proper autoclaving procedures should be for unknown/generic infectious disease. They weren't allowing much time for either to act - only like 3-10 minutes. Proper autoclaving for prevention of unknown/generic infectious disease is 1-2 hours in the US. Prions take even more time. The UK has sent out corrective flyers years ago, though no telling if the all old country doctors paid much mind to them, especially since in terms of results such autoclaving is overkill for most common infectious diseases. Of course better safe than sorry. (You got to love who socialized medicine allows to practice in the back country. On the other hand their amateur science got things started down the proper avenue.)

However if you want to get worked up about the issues of prions on tools in practical medicine see

http://www.journals.uchicago.edu/doi/pdf/10.1086/502391 -- although I note this is circa 2004 and maybe partially outdated.

69.23.124.142 (talk) 15:50, 19 January 2008 (UTC)

The key to the stability is the crosslinking. In solution, dissolved reagents are sorrounded by a solvent sheath, increasing their reactivity (Debye-Huckel Theory). If the reagent and it's solvent sheath cannot penatrate the into the protein, no reaction will occur.

One way to decompase any organic material is using an oxygen ion-plama (cold non-equilibrium plasmas) —Preceding unsigned comment added by Minofd (talk • contribs) 04:44, 13 March 2008 (UTC)

The following reference offers a serious question for the CDC prescription, because it is in tune with the editorial. —Preceding unsigned comment added by 216.234.170.75 (talk) 14:02, 16 July 2009 (UTC)

Self-Replication or propagation of Shape

If prions can influence mRNA translation, then prions would be neither self-replicating nor exceptions to the so called central dogma of modern biology, but proteins that regulate mRNA translation (at least). That is, if prions do not modify their inactive "cousins" (same primary structure or aminoacids sequence, but diferent subsequent structures due to different folding) in the absence of nucleic acids (something that to the best of my knowledge has not been found).

Also, why do you say that the modification of the struture of a protein does not modify its properties (in particular biological, but those are dependant on the shape of the protein and thus all derivated properties -that is, known characteristics- are modified more or less)? That is why by heating to high temperatures (specially in a forceful manner to proteins whose shape is dependant on low energy bonds) enzymes can be deactivated (rupture of these bonds) and also why if the peptide bonds were not broken it is possible that the enzyme will reactivate (reestablish low energy bonds).

I am by no means studying prions (and so i cannot assure you that it han not been shown that prions can modify their "cousins" in the absence of nucleic acids) but i beleive it is a whortwhile question.

Bernardino

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Just because a prion can influence mRNA translation does not mean it's not self-replicating. Also, a prion isn't quite a family of proteins in the same way as say, kinases are. Generally, prion proteins have a normal function, but 'on the side', they have the capability to aggregate and propagate in the prion state. In fact, for several prion proteins, prion propogation actually results in a partial loss of function phenotype.

To address your second question, it was recently shown that URE2, a yeast prion, will form orderd aggregates in vitro at a neutral pH, and that these aggregates retain their infectivity. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16096644&query_hl=16

From what I see, the violation of the central dogma comes from the fact that prions propogate by modifying the conformations of their cousins. I guess I don't really understand how requring nucleic acids to hang around would prove that prions follow the central dogma.

Morwan

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Okay, so prions can survive temperatures of up to 1000 degrees Fahrenheit. Exactly how does their structure allow them to do this? How are they invulnerable to things like cooking and stomach acid? All proteins should be broken down in your body cells! Scorpionman 00:42, 3 May 2005 (UTC)

One explanation could be the independance from fragile bonds, if they were a short protein without cuaternary or tertiary structure they would be much harder to modify in their tridimensional structure (it would only have peptidic and hydrogen bridge bonds). As a matter of a fact, in the absence of highly specific enzymes, many compounds are not broken down even in extremly acid conditions (remember lactose for example, it is a short sugar, disacaride, it is not broken down withouth lactase and so it is not asimilated, however, that birngs the question on how did the protein enter then if it was to big?, just thinking that maybe it is not just size what matters but shape and this protein could somehow be asimilated despite its size, or maybe it is broken but espontaneuosly reforms, something that seems to me very unlikely unless it is a very short protein indeed -like two or three aminoacids-).

Take all this as thinking aloud with VERY LITTLE to think on, I do not consider to be in a position to understand this becuase I have not experimentated with prions nor reviewed enough to consider it to be a significant amount of what is needed to understand this.

Bernardino

You said that 1000 degrees Fahrenheit is hot enough to melt lead. True, but lead doesn't require that high a temperature to melt. It's melting point is so low that it can melt in a wood fire. Anyway, prions aren't really alive, so you can't "kill" them essentially. You would have to use a very complicated process to take them apart. Scorpionman 17:43, 19 November 2005 (UTC)

The info about 1000 degrees and bleach is wrong if you mean indefinitely. While I don't care to look up the reference again myself, the CDC procedures clearly state that prions can be safely destroyed by proper autoclaving. The problem being that many medical autoclaves are too cheap to reach the proper temperature in the first place or are out of calibration. If I remember correctly, autoclaving at 280 degrees for 2-4 hours is one way to safely destroy prions. Alternatively autoclaving with a 5% bleach solution at 160 degrees for 45 minutes works too. But if you do autopsies with possible prion involvement I'd find the CDC reference. I seem to remember that there was also a bleach combo solution for general clean up of surfaces not expected to have potential invasive contact with human tissue (e.g. floors versus scalpels). But it is true prions are not known to be biogradeable in common natural settings. Apparently the urban legend about 1000 degrees etc came from the early amateur scientists who helped discover prions but who did not always produce valid data. 69.23.124.142 (talk) 16:01, 19 January 2008 (UTC)

New synthetic prion

I'm not expert enough on this to do the following justice. Anyone care to add a section on the synthetic prion developed that causes similar brain deterioration in mice? http://www.cnn.com/2004/TECH/science/07/30/syntheticprotein.ap/index.html - Tεxτurε 20:00, 30 Jul 2004 (UTC)

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I've read Stan Prusiners original publication on the "synthetic" prion. While the article gives strong support for the prion hypothesis, there are some issues regarding the design of the experiment. Especially the use of mice which overexpressed PRNP about 16-fold is a critical point in the study. I'd like to let the whole thing settle in for a while before adding this information to the article. Dr. Strangelove 13:39, 6 Aug 2004 (UTC)

brewhaha@ecn.ab.ca: I would favour ignoring that for the jenetik content in artificial mutants, except such things might also hav changes in their metal metabolism. Then again, artificial mutants aren't designed to live in the real world. In the article about TSEs, it goes into more detail about jenetiks, where it should. Maybe that's a better place to discuss synthetic normal prions. 216.234.170.83 06:41, 16 July 2006 (UTC)

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I think it's worth mentioning in the article that the word prion is pronounced "PREE-ON" instead of "PRY-ON" as most people assume... minor detail, but very important to avoid embarassing situations. Brodo 08:14, 19 Mar 2005 (UTC)

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brewhaha@ecn.ab.ca: No matter what the coiners of the word say, I think the etymology "protein ion" (and pronunciation: pry-on, after ion) fits the spelling and meaning of the word more aptly. Noting the interference from jenetiks on this topic, I'm inclined to remove any divergence into the topic. No nucleic acid. No artificial mutants. I think the notes about autoclavure paint a very sharp picture against this group of diseases being caused by protein, too. At 1000 degrees F, protein doesn't just denature. It decomposes. Changes in protein are an EFFECT. I suspect that a metal ion (manganese?) is flattening the protein.

The pronounciation isn't just a matter of what one thinks is apt. It is of what is universally accepted. The spelling has undergone some degree of literary gymnastics. SteveD. 3rd May 2008. 10:35 —Preceding unsigned comment added by 58.168.20.223 (talk) 00:36, 3 May 2008 (UTC)

The Oxford Dictionary of Phrase and Fable excludes things from the definition of prion like this: prion ... Prions are not visible microscopically, contain no nucleic acid, and are highly resistant to destruction.

Is the Phoenix more than fantasy? Can you blame what you cannot see and name it matter of muscle?

Ions of protein or life you cannot blame. It follows that poison is cause of the lame. 216.234.170.83 06:41, 16 July 2006 (UTC)

synthetic prions - not quite

The claim by Prusiner's group to have infected mice with synthetic prions is not as clear-cut as it seems. The mouse line used already had a mutation in its prion protein that causes prion disease. They say around 70% of the animals don't show symptoms within their lifetime, but this does not mean the infectivity is not there; they will have sub-clinical infection.

What they did in this research is to take some synthetic prion protein, containing the same mutation, fold it into a beta sheet form, and inject it. However, it has been shown that you can take an animal with pre-clinical amyloid disease, inject some beta-sheet protein (of any sort) and the disease will be accelerated so that they show symptoms much quicker. The beta-sheet protein seems to 'seed' the pre-existing amyloid so that the disease progresses faster. The research done in this paper is not novel - similar results have been reported before.

The true holy grail of prions is to take some pure, recombinant, wild-type PrP^C, do something to it, then inject it into a wild-type mouse, and cause disease. Nothing close to this has been achieved, though I think it will be at some point. --Purple 01:48, 19 May 2005 (UTC)

Prion Terminology

The term prion isn't clearly defined in the article, it seems to suggest that prion proteins exist solely to aggregate, and do not have any normal cell function.

Morwan 18:50, 22 December 2005 (UTC)

Early in the history of the article, I had added a sentence to suggest that prions may be thought of as auto-chaperone's. I thought that was a fairly good way of defining prions in terms of what was already known. [3]. Many other papers suggest the connection between prion and chaperone proteins. Unfortunately I am not an expert on the subject :( Shyamal 06:30, 31 January 2006 (UTC)

Errors ID'd by Nature, to correct

The results of what exactly Nature suggested should be corrected is out... italicize each bullet point once you make the correction. -- user:zanimum

• It should first be clearly stated that prions replicate through conversion of the host normal prion protein (and not any other host protein).
• It is untrue that prion domains are flexible and lack a defined structure. On the contrary, prion domains are fold into structures called alpha helices in the normal conformation and are stretched into flat structures called beta strands when in the "prion" state.
• Unclear: Regarding the normal cellular prion protein, its precise location is at the surface of all cells. It is untrue that its function is not known, rather it is not completely resolved.
• Unclear: Concerning propagation of prions, it is not the disease which is propagated but the infectious agent (prions).
• The sentence linking prions to memory and cellular differentiation is extremely misleading. The normal function of cellular prion protein in mammals is not fully understood, but it may take part to cell adhesion mechanisms, cell signaling, copper homeostasis, and protection against insults such as oxidative stress.
• Bias; A very (too) long part of the entry is about yeast prions, as compared with mammalian prions. The occurrence of prions in yeast is interesting in so far as it gives credence to the protein only hypothesis.
• It also has allowed to shed some light on the prion domains (i.e. regions in the protein involved in the conversion) and on the mechanisms of conversion. However, it is untrue that prion-like proteins are found in "many" plants or animals (we just do not know). The word "useful" is also confusing, while it is true that not all prions are associated with a "disease" state.

--Purple 02:49, 2 February 2006 (UTC)

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In order to resolve the 'bias' issue, would it be best to split off the prions in model organisms into its own article? I still think that prions in model organisms should be an integral component of this article: Sup35p has been studied for decades and may be considered the 'best-understood' prion. An expansion of the mammalian section of the article should be done, obviously. Maybe the tables are a bit too much information for a general article... Maybe those should be placed in seperate articles?

Someone want to help me work on a yeast/model organism prion page?

Morwan 23:48, 22 December 2005 (UTC)

Revisions post Nature review

As a major contributor to this article, I feel as if I should chime in on the Nature review, which was generally fair and helpful.

-It should first be clearly stated that prions replicate through conversion of the host normal prion protein (and not any other host protein).

-Noted and corrected

-It is untrue that prion domains are flexible and lack a defined structure. On the contrary, prion domains are fold into structures called alpha helices in the normal conformation and are stretched into flat structures called beta strands when in the "prion" state.

-Clarified that this section refers to yeast prion domains, not to PrP. However, only a part of the Prp-C conformation is alpha-helical; major portions of the protein's structure have not yet been defined.

-Unclear: Regarding the normal cellular prion protein, its precise location is at the surface of all cells. It is untrue that its function is not known, rather it is not completely resolved.

-Noted and corrected

-Unclear: Concerning propagation of prions, it is not the disease which is propagated but the infectious agent (prions).

-I've clarified this point to make it clear that the infectious agent is replicated, propagating the disease state between cells and (potentially) animal hosts.

brewhaha@ecn.ab.ca doesn't think this is a big deal at all. If the phenomenon wasn't a disease, then it wouldn't involve an infectious agent. Someone is splitting hares. 216.234.170.85 12:55, 14 July 2006 (UTC)

-The sentence linking prions to memory and cellular differentiation is extremely misleading. The normal function of cellular prion protein in mammals is not fully understood, but it may take part to cell adhesion mechanisms, cell signaling, copper homeostasis, and protection against insults such as oxidative stress.

-I've always been skeptical about the Lindquist and Kandel papers linking learning in Apleisa with a prion mechanism. I agree with the reviewer that this discussion point should be deleted.

-Bias; A very (too) long part of the entry is about yeast prions, as compared with mammalian prions. The occurrence of prions in yeast is interesting in so far as it gives credence to the protein only hypothesis.

-I disagree. The yeast prion field is miles ahead of the mammalian prion field, and unlike the mammalian prion diseases, fungal prions are wide-spread in nature, diverse in protein sequence and function, and potentially are adaptive rather than pathological. Readers interested mammalian prions can click through to the many TSE links.

-It also has allowed to shed some light on the prion domains (i.e. regions in the protein involved in the conversion) and on the mechanisms of conversion. However, it is untrue that prion-like proteins are found in "many" plants or animals (we just do not know). The word "useful" is also confusing, while it is true that not all prions are associated with a "disease" state.

-I disagree (see [4]) and have added this citation to support this claim

I've updated the error table in the outside review article to indicate that the requested revisions have been completed.

yeastbeast

The word "replicate", when talking about prions, is not very appropriate. The replication is a very complex process, involving many different molecules, reactions, and is under some type of error check, it is not a mere switching from one stable protein conformation to another. "Self-propagating" used by the authors of

this article, for which you have provided the link, is a lot better.

[5]: Thinking about that a bit more, "propagation" alone, of the trait might work nicely, because I'm getting the impression that "replication" is reserved for jenetiks. 216.234.170.74 13:23, 31 July 2006 (UTC)

This text (in the "Into" section):
that prions are responsible for a number of previously known but little-understood diseases generally classified under transmissible spongiform encephalopathy diseases (TSEs)
, and the text at the end of the "Prion hypothesis" section"
The degenerative diseases caused by prions are known collectively as "transmissible spongiform encephalopathies" or TSEs
say almost the same thing.

brewhaha@ecn.ab.ca agrees. Why repeat yourself with LESS detail? 216.234.170.85 12:55, 14 July 2006 (UTC)

This text:
Because of this, scientists reasoned that such proteins could give some sort of evolutionary advantage to their host. - is crap, of coooourse THEY DO, otherwise why loose the genes for the synthesis of the very important vitamin C and keep the ones for the "nasty" prions, plz remove this "great reason of the human mind" of whoever-said-it. I'll see if i can contribute a bit. -- Boris 18:50, 25 December 2005 (UTC)

brewhaha@ecn.ab.ca says that it definitely bears repeating that genetics were ruled out of the prion hypothesis at inception. They therefore hav nothing to do with a major difference between rats and humans. <opinion> The artificial mutants with a predisposition to produce pathological protein probably hav a difference in their sensitivity to an elemental poison -- a difference in their metabolism of an element. </opinion>216.234.170.85 12:55, 14 July 2006 (UTC)

About the advantage thing, even if it's blatantly obvious, there might be layreaders who wouldn't come to that conclusion. -- Natalinasmpf 22:20, 25 December 2005 (UTC)

Yeah you are right, but it also makes those whoever-sayers look stupid in the no-layreaders eyes. -- Boris 22:59, 25 December 2005 (UTC)

Maybe you could be bold and find a better way to phrase that passage? :) - Samsara 02:07, 7 January 2006 (UTC)

I also disagree with the reviewer's comment that yeast prions are less interesting than mammalian prions - I think this is itself a biased opinion. Yeast/fungal prions are a very different phenomenon to mammalian prions, i.e. fungal prions are a completely new mechanism of epigenetic inheritance involving many species/proteins, while mammalian prions are just related to a limited range of diseases. I can therefore see why it's difficult to discuss them both in the same article, I think there's an argument for having separate bits for prions (disease) and prions (regulatory mechanism). Not sure how that would work though...--Purple 19:16, 22 January 2006 (UTC)

Genetic material

As written, the Genetic material article seems to imply that prions are living organisms and have genetic material that is not DNA. --JWSchmidt 22:36, 25 December 2005 (UTC)

I've done my best on that article, but someone needs to add the names for normal and evil prion to complete the exposition. - Samsara 02:03, 7 January 2006 (UTC)

prion strains

Hmmm the first section explains what a prion is, then later on there's a table of different prion isoforms, with no explanation of what a prion isoform is or how one protein can cause all those diseases. Maybe we need a section explaining prion strains, especially since the existence of strains is one of the things that prion-sceptics get most twitchy about. --Purple 14:27, 22 January 2006 (UTC)

brewhaha@ecn.ab.ca: This Flat Earther isn't twitchy about prion strains at all. If I ignore the topic, then jeneticists will eventually occlude the theory of self-propagating protein deformation with a theory of inheritable disease. If I don't ignore it, then I'll find evidence that the strains are malleable, meaning that manipulating the salts of their solution will change their strain. 216.234.170.83 07:06, 16 July 2006 (UTC)

---

Some references for prion "strains". These "strains" seem to be in some way related to structural/conformation variations in the prion protein.

• Analysis of Prion Strains by PrP(Sc) Profiling in Sporadic Creutzfeldt-Jakob Disease
• Conformational variations in an infectious protein determine prion strain differences
  

--JWSchmidt 15:38, 22 January 2006 (UTC)

Anyone got any objections to me sticking a section in? However it would be from the point of view of mammalian prion disease only unless someone else can do yeast strains--Purple 19:18, 22 January 2006 (UTC)

A discussion of strains would be quite helpful. If Purple wants to add a bit about the PrP strain phenomenon (distinction between FFI, CJD and GSS, for instance) I could add a bit about conformational variation in [PSI+] yeast prions (my area of specialty). However, the article is now a bit disjointed with the bulk of the yeast prion information in a separate article, yet retaining the technical discussion of yeast prion structural features. Perhaps prion strains should be a small, non-technical section with a link to a more comprehensive article. Yeastbeast 08:30, 29 January 2006 (UTC)

brewhaha@ecn.ab.ca: I must've gotten the idea for putting most of the jenetics under TSEs from you. 216.234.170.83 07:06, 16 July 2006 (UTC)

One of the most remarkable features of prion disease is the existence of distinct prion strains with well-defined heritable properties. These strains were originally characterized by incubation time and resultant neuropathology (Bruce et al., 1992), but they can also be differentiated on the basis of PrPSc distribution in the brain and physicochemical properties of PrPSc such as resistance to proteases and how they have been glycosylated - their 'glycoform ratio' (reviewed in: Bruce et al., 1996). As different prion strains can be serially propagated in mice with the same Prnp genotype, they can not be encoded by the primary sequence of PrP. It is now thought that strain specificity is determined by PrP conformation and glycosylation. Different PrP conformers could interact with varying efficiencies and glycosylation may influence where in the brain a strain may target (Collinge et al., 1996;DeArmond et al., 1997). It is known that different cell types may glycosylate proteins differently, therefore particular PrPSc glycoforms might replicate most favourably in those cells expressing a similar PrP glycoform. This regional targeting could also explain the differences in incubation times between various strains with targeting of more critical brain regions resulting in shorter incubation periods. Pikzee 17:35, 21 March 2007 (UTC)

PRP acronym

"Prion-related protein"? I thought PrP stands for Protease-Resistant Protein. Someone please clarify and maybe even make an appropriate link from the acronym disambiguation page PRP. Alex.g 17:04, 17 February 2006 (UTC)

Yes I think that was how PrP got its name originally, but that was before people knew it also came in a 'normal' form. So by general consensus it's now known as 'prion protein' (now I think about it no-one really refers to it as 'prion-related' protein). I suppose that could go in the article for thoroughness. --Purple 03:17, 18 February 2006 (UTC)

Yes, when Stanley Prusiner did his studies in 1982, he found the DNA sequence that codes for the prion that causes scrapie and CJD. He called the protein a PRP (protease-resistant protein). I don't believe that it has changed meaning since then, since the term is still accurate. --Bona Fide 10:23, 4 March 2006

brewhaha@ecn.ab.ca My orijinal impression of the word, "protein ion", (which I pronounce pry-on, despite Webster and the IPA, which disagree, so that I'm tempted to delete one or fix the other) relates to the binding of copper to it as if the protein wer charjed. I'm using flat prions for sick prions and I'll use twisted prions for healthy prions if it comes up. Burn the alphabet soup.216.234.170.85 22:16, 14 July 2006 (UTC)

I think PrP stands for "Prion-related protein" it narrows down the identity more than "Protease-Resistant Protein".

actually, PrP stands for "proteinaceous particle" as coined by Prusiner in order to distinguish PrP^SC from conventional viruses (Prusiner et al 1982). Jesse.maegan (talk) 01:59, 20 September 2008 (UTC)

How does it stay 'alive?'

Biology is not my strong point, but when a cow dies of BSE, and if its remains are eaten by another cow, should the Prion protein not have been destroyed when the original cow died (maybe by proteolysis) and should it not be digested in the other cow's stomach? I just don't get how the endogenous Prion still sits in its abnormally conformed shape even after the host has died? Anyone?

Prions aren't affected much by proteolysis or anything else. Otherwise the animal would be able to break them down when it's alive. You can put prions in formaldehyde, boil them, in fact boil them in formaldehyde if you like, whatever - they survive a lot of stuff (their structure is very stable) --Purple 03:42, 10 March 2006 (UTC)

~ User:Unfortunate

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Something's gotta be alive before you can kill it. As Purple mentioned, they're extraordinarily resilient. Most typical biocidal agents and tactics are futile efforts. I have no first-hand experience with them, but from the few bits of information I've collected through research over the years, prions have been heated to thousands of degrees, directly immolated with plasma torches, bombarded with high-energy gamma rays... no dice.

Methods such as those tend to destroy a significant percentage of prions in any particular sample, but, as far as I am aware, there is no known way to destroy them all, atleast not in a living organism. They really are nasty little things. They undergo self-replication, but exhibit no free will, and so fall below the threshold separating life from nonlife. This means that, unlike biological reproduction, the propagation of prions consists of completely deterministic chemical interactions, which makes the prevention of their replicative process much, much more difficult than stopping a living, infectious organism.

Alexis Brooke M 04:06, 5 November 2007 (UTC)

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

This could pose a serious problem in future outbreaks, it has been found that the prion protein excerted by scrapie infected sheep can remain in the soil for extended periods of time and infect flocks that are later allowed to graze on the same pasture. It is thought that animal carcases may also release the disease into the soil contaminating it for years to come! Britian is the place to watch after the massive outbreak that occured in the 90's! (A.guinness (talk) 00:49, 27 May 2008 (UTC))

Lamarkian evolution

Can prions really be said to instance the inheritance of acquired characteristics?

brewhaha@ecn.ab.ca doesn't think so. If I'm not mistaken, the only vector for acquired characteristics other than the DNA of your cells is the DNA of your mother's mitochondria, which come strictly from your mother, and these prions haven't been shown to influence DNA. They are not mutajens. 216.234.170.85 12:55, 14 July 2006 (UTC)

I am certainly not expert in this field but I think I understand this article to say that PrP^Sc is a protein coded for by dna as is any other protein.

The fact that the form of the prion is in some way contagious does not affect the offspring of an infected organism, one whose dna does not itself code for the prion itself, or does it? Jfmxl 03:29, 28 March 2006 (UTC)

brewhaha@ecn.ab.ca: That's another vote for somehow making it clear that this topic is not about genetics without deleting references to genetic experiments, which is exactly what I would do if this were a personal web page. DNA codes for prions, and it doesn't encode their shape. I hope that's a principle, because I'm looking for a way to find it. Hmmm. DNA does not encode the folding or shape of protein. It seems to be false according to the part about jenetiks under TSEs, but I can't rule out the possibility that the prions it is talking about involve a different amino acid sequence. 216.234.170.83 07:14, 16 July 2006 (UTC)

• I'm not so clear on the justification for mammalian systems, but with fungal prions it's pretty obvious that prions are acting as epigenetic elements. Two genetically identical cells will have significantly different phenotypes depending on their prion state. Once a cell becomes PRION+ (prion probegteins are aggregated), it and virtually all of its offspring will be PRION+. Occasionally there is reversion to a prion- (not aggregated) state, but it's extremely rare. Morwan 08:51, 28 March 2006 (UTC)

brewhaha@ecn.ab.ca: Rare, you say? Take an empty two litre bottle of pop. Put 2/3 cup of molasses and 1.25 litres of water in it. Sink a cap of your favourite fungus into it. You'll get non-aggregated yeast, or perhaps semi-aggregated yeast. Take out the cap. Dump the liquid into a pail of sawdust or grass clippings. You'll get aggregated yeast: caps. 216.234.170.83 07:14, 16 July 2006 (UTC)

• PrP is a protein sequence coded by DNA as any other protein. PrP^C is native folding state of this protein (unfortunately I have no information in function of PrP, but it should have some functions in organism as we all have this protein). PrP^Sc is different folding state of PrP - it has different secondary structure and aggregates forming amyloid fibrils. PrP^Sc is not native state of PrP and appears only because of special conditions - like mutations or presence of already formed PrP^Sc which pushes PrP^C to change structure. V.S.

I think the case for prions exhibiting Lamarkian evolution is this: Lamarkian evolution claims that an individual aquires a trait during its lifetime and then passes that trait on to its young. If we consider PrP^C an individual, which aquires a new trait and thus becomes PrP^Sc, it then goes on to cause other PrP^C proteins to misfold and become PrP^Sc (its offspring). The error came from assuming that evolution implies inheritable genetic traits.

the begining of a lifeform, evolution before our very eyes? 81.159.158.247 16:50, 1 December 2007 (UTC)

Is Prion a common name for all proteinaceous infectious particles?

During last years there were showed that other proteins can form amyloid fibrils which can seed native proteins making them change structure. Means these amyloid fibrils are proteinaceous infectious particles. Some of these proteins can even form different strains [6] So can we call such proteins prions? Or prion is only PrP and it is only one of amyloidogenic proteins like AmyloidBeta, IAPP, TTR which are also related to some diseases, or insulin, which can can behave similar to prions in certain conditions, but by now it was not involved in amyloid diseases?. V.S.

[7]: In its coinage, prion is PrP^SC or beta amyloid. I hesitate to use "prion" in a positive context for normal function (if I can figure that out, if any), because of the coinage, so I might work it like this:
PrP^SC: Beta Amyloid.
PrP: prion (I won't write TLAs unless I really can't think of something pronounsable).
PrP:^C: normal prion.

Beta Amyloid is usually conjoined with plaque. 216.234.170.74 13:09, 31 July 2006 (UTC)

Beta-amyloid tends to refer to the peptide involved in alzheimers disease, and thus isn't really related to prions.

Other amyloid diseases are not infectious. A bit of amyloid from a someone with a non-prion disease cannot spark off the disease in a healthy person; a prion can - that is the key difference. There are other proteins than PrP that can form prions (i.e. that are truly infectious), but the only ones we know of are in yeast/fungi. You also need to bear in mind that 'amyloid' itself (beta-sheet protein fibrils) is not necessary for prion disease - it seems to build up as a kind of by-product. No-one knows what the actual infectious form looks like, or why other amyloid-forming proteins don't have this infectious form.

In my mind, the prion is the actual infectious form, which is not necessarily PrP^Sc (PrP^Sc is the name for the amyloid form of PrP). PrP^C is the 'healthy' form of PrP, while PrP on its own refers to any structure of PrP. I would say that PrP is prion protein, while 'prion' alone means specifically the infectious form. Purple 13:03, 3 January 2007 (UTC)

---

Actually, the nomenclature of the various forms of PrP is still debated amongst prion researchers. For clarification, I've listed below just a few of the different names for some of the isoforms of PrP as outlined by Prof Charles Weissmann in his excellent review, The State of the Prion (Nature Reviews Microbiology 2, 861-871 (2004)).

PrP^C

The physiologically occurring, mainly GPI-linked form of PrP, or prion protein, that can be glycosylated on one or both of two asparagine residues with a variety of glycans. As shown by NMR and X-ray crystallography, it is rich in alpha-helical structure and contains only a little beta-sheet structure.

PrP^Sc

An isoform of PrPC that is almost invariably detected in TSE-infected tissues and cells. It comprises a carboxy-proximal segment of about 140 residues that is resistant to defined conditions of PK treatment. The term PrPSc is used by some interchangeably with prion, a usage that should be avoided. PrPSc designates a structure, prion is a functional concept. The implication that a particular form of PrP is the only essential constituent of the prion remains to be proven.

PrP^27-30

The PrP fragment remaining after controlled PK digestion of PrPSc. - Contrary to popular belief PrPsc is not entirely resistant to protease digestion, but instead has a protease-resistant core. (Pikzee)

PrP*

A hypothetical isoform of PrP that is the essential component of the TSE agent or prion.

Prnp

The gene encoding PrP

rPrP

Denotes recombinant PrP. When produced in Escherichia coli it lacks the GPI anchor and the glycan residues.

Pikzee 17:57, 21 March 2007 (UTC)

the "umbrella term" for amyloid-forming particles such as those seen in alzheimer's, parkinson's, huntington's, and prion-related diseases is "amyloidogenic synaptopathies".

Jesse.maegan (talk) 02:02, 20 September 2008 (UTC)

Fungal Prions 'Controversial'?

This statement is in the Fungal Prions section:

"This definition is controversial, since these proteins were not initially labelled as prions due to their infectivity, but because of their amyloid nature. It was not untill later that the potential for infectivity was discovered, and it is still not clear if infection occurs naturally."

Would you care to justify that? Long before they were determined to be prions, URE2 and PSI were studied because of their non-mendelian inheritance, which has been determined to be a consequence of their infectivity.

Morwan 01:05, 8 April 2006 (UTC)

Genetics or not?

brewhaha@ecn.ab.ca Two sentences near the start of this article hav TSEs as explicit subjects. I've set them off with . I also want to take out the bit about Lamarkian Evolution, because the example cited does not seem to reach DNA. It only goes as far as biological maladaptation. I'd like to believe in Lamarkian evolution, too, and I don't know of a mechanism for it that isn't mutagenic or that doesn't involve spermicidal or ovicidal effects.

I saw some passive voice in the article that isn't necessary, so I doubt that anyone has gone over this with Grammatik. I'm hoping that I can drop the required grade level with no significant change in meaning. Otherwise, there'll be too much shock at suddently being able to understand the article when someone gets to the part about dissent. I'm expecting complaints from Grammatik about the acronyms, so I'll use them once and thereafter try to spell things out. 216.234.170.83 08:52, 16 July 2006 (UTC)

Alzheimer's and prions

[8]: In Neuroinflammation in Alzheimer's disease and prion disease, I found support for both my speculation that prions relate to inflammation (immune system) and an addendum to a remark I made about Alzheimer's. As of yet, neither TSEs article nor prion article mention this neurodejenerativ disease. 216.234.170.74 12:46, 31 July 2006 (UTC)

BTW, I like Wiley's interface to their own abstracts more than NIH.

Section on Dissent

In paragraph fifteen of Brown's work, it explicitly says "There is currently no evidence that this manganese bound prion protein is infectious", so whoever was trying to say that Brown supports the protein-propagated cause of protease resistance was sorely misled.Brewhaha@edmc.net 20:33, 27 October 2006 (UTC)

Why does one of the paragraphs have a strikethrough through it?

Why is that so? Is it because the information is wrong, or is it someone's idea of a joke?

brewhaha@ecn.ab.ca: Maybe you should ask yourself why the whole section about "proposed mechanism of prion propagation" disappeared _without_ tags for warning. My version's going on bionet. 216.234.170.65 20:51, 16 July 2006 (UTC)

brewhaha@ecn.ab.ca: The paragraph you mention clearly relates to encephalopathies TSEs, but not diseased prions, which are not supposed to propagate with genetic reproduction. Even though they apparently do in the article about TSEs, the phenomenon is very rare. But really, when you talk about prions, you are invoking the topic of non-genetic propagation of biological characteristics.

I'm learning why copywriters normally get paid. As I activate and simplify the sentences to make this article more readable, some of them are actually getting redundant, repetitive and dogmatic, and I didn't like them to begin with, so I'm glad someone's watching, because on the first pass of my revision, I'm doing very little to the content. Just that part about TSEs and another bit about Lamarckian evolution. I'll let the change in style sink in for a while.

As for the bias in my section about dissent, no other explanation allows for this disease to survive incineration. And I think I will expose some bias under a veil when it comes to passive voice. 216.234.170.65 18:34, 16 July 2006 (UTC)

Kuru and Prions

I'm not sure if this is the right place to put my question, but I'm doing a research project on the Kuru disease and I'd like to know what exactly prions do that cause the brain to get "spongy".

Now, from reading the Prion article, I get that the PrP^Sc protein contains a lot more of the amino acid structure called "beta sheets" than the normal PrP^C proteins. Now assuming that HuPrP^Sc kuru protein is somewhat related to the PrP^Sc protein, these "beta sheets" allow the proteins to form insoluble fibrils called amyloid aggregations. How do these fibres cause problems? I'm only a grade 10 student, so I'd like a somewhat simplified answer so that I can understand what you are saying without having to research every word I don't understand. Your help is appreciated.

brewhaha@ecn.ab.ca: Amyloid aggregations have been found in Alzheimer's, too. Even with the revisions I'm submitting, this article has a grade 11-13 reading level according to mechanical scores. I've made my version just a bit easier to read than an insurance policy, and it's difficult for me to see if I'm incorporating all of the revisions I mean to, because Grammatik (my style checker) isn't compatible with the markup here. 216.234.170.65 20:21, 16 July 2006 (UTC)

Very basically put, the loss of the PrP^C form of the protein results in the death of the cell. in most cells this is not noticable because the body replaces its cells any way, however this process does not occur in the brain, consequently small holes are left in the brain where the cells have died leaving the sponge like appearence. A.guinness (talk) 00:59, 27 May 2008 (UTC)

PrP-knockout mice live. That doesn't contradict your assertion that losing common prion would be deadly. If I were to assume you to be correct, then I would wonder if PrP-knockout mice are missing all proteins found in amyloid tissue. BrewJay (talk) 23:47, 4 July 2008 (UTC)

Summary List

I notice that over time the article gradually seemed to concentrate more and more on BSE and its variants and leave out the other prion diseases. I think that it is useful to include them for the reader so they can see that this covers a wide range of diseases, and not just the BSE/TSE type. I have put the summary list at the bottom which existed in shortened form when the article was first started.--ReasonIsBest 17:15, 23 November 2006 (UTC)

Thanks, ReasonIsBest. I think that your edits are an improvement. – ClockworkSoul 17:17, 23 November 2006 (UTC)

Prion Genetics

Does anyone know if the prions that are considered human pathogens have ever been genetically mapped out and their protein functions understood? I am interested in those that affect the brain specifically

Function is very topical, here. Genetic work was done to knock out the protein that can become protase resistant in mice. How are PrP-knockout mice different from other mice? I'm not sure that you understand the difficulties in understanding function, even after you know structure. I don't think half of what cellular structures do is written or accurately modelled. I don't even hav a standard for accurate model. BrewJay (talk) 23:38, 4 July 2008 (UTC)

Why was this removed?

Therapeutic strategies

Recently Japanese scientists at the Obihiro University of Agriculture and Veterinary Medicine developed one of the first strategies to delaying the onset of disease. They found that sulfated glycosaminoglycans (GAGs) and sulfated glycans inhibit formation of protease resistant protein in cells and prolong the incubation time of scrapie-infected animals. Among the glycopyranosides and their polymers examined, monomeric 4-sulfo-N-acetyl-glucosamine (4SGN), and two glycopolymers, poly-4SGN and poly-6-sulfo-N-acetyl-glucosamine (poly-6SGN), inhibited PrPSc formation with 50% effective doses below 20 microg/ml, and their inhibitory effect became more evident with consecutive treatments. Structural comparisons suggested that a combination of an N-acetyl group at C-2 and an M-sulfate group at either O-4 or O-6 on glucopyranoside might be involved in the inhibition of PrPSc formation. Furthermore, polymeric but not monomeric 6SGN inhibited PrPSc formation, suggesting the importance of a polyvalent configuration in its effect. These results indicate that the synthetic sulfated glycosides are useful not only for the analysis of structure-activity relationship of GAGs but also for the development of therapeutics for prion diseases.

Is it bad? --Filll 01:32, 30 November 2006 (UTC)

I didn't remove it, but I couldn't do much about

the alphabet soup in it, either. Maybe it should be tersened a lot. Brewhaha@edmc.net 09:18, 30 November 2006 (UTC)

Looking at it carefully, I wonder if these treatments could remove or sequester an ion like Manganese with its high valences. With so many potential ligands stuffed into one paragraph though, I don't see an opening to introduce chelation. Brewhaha@edmc.net 10:02, 8 May 2007 (UTC)

Exotic Ungulates

Can anyone state a good reason to separate one kind of hoofed animal from another? Brewhaha@edmc.net 09:18, 30 November 2006 (UTC) The section on exotic ungulates is currently red, because it's not in the wiki. Brewhaha@edmc.net 09:18, 30 November 2006 (UTC)

If you look in the scientific literature of the field, this is done commonly. For many TSEs, similar things are done. I am not sure if there are more subtle reasons, however.--Filll 14:15, 30 November 2006 (UTC)

Prion discovery attribution

• I've removed three edits regarding the attribution of a "Dr. Deshpande at Cambridge University" as the discoverer of prions -- a PubMed search for "Deshpande AND prion" returns zero results. References? -- MarcoTolo 01:09, 22 January 2007 (UTC)

"deshpande protease resistant protein" offers four hits on three different researchers, none of them topical, none of them dating to before the eighties. I seem to remember a different name for the source of this concept. BrewJay (talk) 20:31, 4 July 2008 (UTC)

Spelling of Purdey

A minor change, but I corrected Mark Purdey's name from "Purdy". He was a member of the Purdey gunsmith family. Jonathan Silverlight 23:24, 22 January 2007 (UTC)

Are they disease agents

While prions exist there is still much debate whether they are the causal agents of disease. In a recent stucdy conducted by Johns Hopkins 12% or their researchers reported they show no evidence they do cause illness and suggest other germs may be at fault. Whether or not you agree with this, enough people disagree to at least present an opposing viewpoint in this article. If you can do so for HIV and vaccines you can do so for prions. —Preceding unsigned comment added by 4.142.45.67 (talk) 2007-02-24T21:04:40

It it not clear (to me, a non-expert) exactly which viewpoint it is that you want presented. This depends on what one takes a "prion" to mean:

• The introduction to the article suggests that something is a "prion" if and only if it is a proteinaceous substance that transmits a disease. Under this definition, however, it is meaningless to claim that "prions exist but do not cause disease".
• Another possible definition would have a "prion" be any protein that has a configuration which is unusually resistant to denaturation/proteolysis.
• A third possibility is that a "prion" is any protein with two possible configurations of which one catalyze the transformation of the other into itself. But the article seems to suggest that there is still doubt about whether this is actually true for PrP.
• Finally "prion" might simply be an alternative name for the specific protein PrP and its homologues in different species.

I suspect that the lack of a clear definition in the article reflects a lack of scientific consensus about what the word ought to mean, but if so, that uncertainty itself deserves mention, I think. –Henning Makholm 22:15, 24 February 2007 (UTC)

Blood-brain barrier

Even if prions can resist digestion and make it into the bloodstream, how the heck do they get past the blood-brain barrier? ---Seven of Nine 19:17, 17 March 2007 (UTC)

Prions are believed to enter the brain through neuroinvasion (traveling along the nerves). After infectionof an animal/person, they enter the lymphoreticular system where they replicate (Kitamoto et al., 1991), particuarly in the spleen. They then travel from here into the sympathetic nervous system in a process which requires Follicular Dendritic Cells (FDCs) . It is not known how the prions move from FDCs into nerves as there is no physical contact between them. Once in the sympathetic nervous system, they can travel into the central nervous system and therefore, into the brain.

Pikzee 17:06, 21 March 2007 (UTC)

That answer makes no sense. If Brown's depiction of the structural protein that can become protease resistant amyloidosis is correct, then it is not a neurotransmitter. To me, it looks like part of a cell wall, if not an ionophore, so I vehemently reject this concept of prions travelling along the nerves. Ions do that. Neurotransmitters do that. Prions are too big for anything like that. 216.234.170.107 (talk) 22:33, 21 July 2009 (UTC)

Ok, obviously I should have spelt this out more clearly. You're right, the prions are not traveling down the nerves in the same way as ions. The prions replicate in the spleen and are carried by the FDCs. FDCs accumulate high levels of prions (PrPSc) during the infection and essentially "pass them" to the splenic nerves. It's not known exactly how this happens but it has been shown that neuroinvasion is dependant on this process and occurs more quickly the closer the FDCs and the nerves are to each other. PrPc is present on the cell membrane of the nerves and it recycles between the membrane and internal compartments of the cell. Once it comes into contact with PrPsc from the FDCs, the conversion reaction may occur - whether this happens in the cell membrane or internal compartments is still unclear. The newly formed PrPSc can then go on to recruit and convert more PrPc within the cell into the abnormal infectious form. Through this continuing process, the prions may propagate or "travel" through the cell and pass from one cell to the next mediating the neuroinvasion. Pikzee (talk) 14:54, 21 December 2009 (UTC)

How do prions get into the brain?

Kuru and vCJD are known to be transmitted to humans who have eaten the meat or brains of infected animals (or, in the case of Kuru, infected humans).

This raises the question: how can prions, which are merely proteins, make their way through the gut and into the brain, where they cause the dreaded spongiform encephalitis? Proteins normally are digested down to amino acids in the gut, and transported through the gut epithelium by amino acid transporters. If that was the case for prions, they would no longer be prions by the time they were absorbed through the gut wall, and would no longer be infectious.

I'm snipping this FAQ style, persuasive stuff out. It involves synthsis.

It's not externally sourced. It follows a lot of minor metabolic pathways. To top it off, it doesn't provide a way to verify the possibilities in action. :

First of all, prions resist digestion in the gut. They remain intact proteins and are known to accumulate in the distal ileum. They resist digestion because they are extremely resistant to all forms of degradation. They also resist destruction by high-temperature autoclave and by formaldehyde, and in fact, by most means tested so far. In fact, cases of vCJD have been known to be contracted from properly sterilized surgical instruments.

But, even if prions are not digested, they should not be absorbed across the intestinal wall. In fact, they circumvent the normal process of intestinal absorption by passing into the gut-associated lymphoid tissue (GALT). Related to this, it seems that chronic inflammation predisposes to prion infectivity, e.g. in rheumatoid arthritis, type-I diabetes, or Crohn’s disease.

The cellular basis for prion transmigration from the gut through the GALT into the lymphoid system is still poorly understood. Membranous epithelial cells (M cells) are believed to be the key sites of antigen sampling for the mucosa-associated lymphoid tissue (MALT), and function as major ports of entry for pathogens from the gut by transport across the epithelium. Immune cells are crucially involved in the process of neuroinvasion following oral administration: mature follicular dendritic cells (FDCs), located in Peyer's patch, could be crucial for the transmission of prions from the gastrointestinal tract. FDCs, being mobile, could function as a bridge between the gut lumen and the lymphoid organs, where the prions can replicate. FDCs could transport prions from their sites of replication to peripheral nerves in lymphoid organs, thereby enabling the process of neuroinvasion.

Fatal Familial Insomnia

"... Fatal Familial Insomnia, a British disease that cultural preferences may cause."

This whole sentence not only sounds strange to me, I also couldn't find any proof for it. Even the Wikipedia article says that the first case was found in Italy and there are cases worldwide. Also, it is genetic, so which British cultural preference causes that?

Aluminum in tea. Incorrect distinction between Alzheimer's and Fatal Familial Insomnia.

BrewJay (talk) 22:52, 4 July 2008 (UTC)

prionic size and infectivity

Hai, work this intom the page: "NIAID Scientists Characterize the Most Infectious Prion Protein Particles" (2005). -lysdexia 04:24, 21 March 2007 (UTC)

Yes, it's quite important for the nature of the infectious agent - the identity of which is still debatable. Even in highly purified infectious fractions, only one in 10⁵ PrPSc particles is infectious (Bolton and Bendheim, 1991). The most infectious prion protein particles have now been shown to be non-fibrillar particles containing 14 – 28 PrP molecules with infectivity significantly reduced in oligomers larger and smaller than this (Silveira et al., 2005). This is also in agreement with an emerging theme in other neurodegenerative disorders (such as Alzheimer's Disease) that the formation of amyloid may actually be a protective mechanism used by the cell to limit the ability of a toxic protein to trigger more conversion. Pikzee 18:13, 21 March 2007 (UTC)

Radical ideas -- thoughts?

Might naturally-occurring "prion"-like protein forms be partially responsible for the natural cell differentiation in embryos?

That depends on a degree of "prion"-likeness that's hard to quantify. I don't even know what kind of numbers for kinetics you would be looking at. BrewJay (talk) 20:48, 4 July 2008 (UTC)

Might "relatives" of modern prions have been responsible for the development of eukaryotic organisms from prokaryotes? Or otherwise have played a major role in evolutionary history?

Layers upon layers of premises and precepts. These topics would be so hard to nail down and so far outside of everyday experience that I wouldn't even try. BrewJay (talk) 20:48, 4 July 2008 (UTC)

Please don't misinterpret the research

Someone is trying to say that transgenic mice lead the way to a cure. Maybe they do, but I'm inclined to say that they'll lead to a prevention more quickly. Let me put it this way: Remission is the wrong word for a mouse that was born to avoid the disease. Brewhaha@edmc.net 11:44, 6 August 2007 (UTC)

The mice in the Mallucci study where modified to facilitate the disruption of the PRNP genes as a means of depleting PrPc after infection and the development of early symptoms. The reversal of impairment without the cure of the underlying pathology would seem to me to warrant the description as a remission. It is the remission of symptoms after the onset of the disease that is of interest in this study and which offers the basis for research into further applications.

This research is quite preliminary and would probably be better referenced in another section of the article rather than the title section. Cobratom’s edit which claimed that early treatment could cure prion diseases was not supported by the substance of the reference and was I felt misleading. I think changing the bred to genetically modified would be both true to the reference and would not over represent its scope and importance.--Camarath 11:45, 7 August 2007 (UTC)

Obvious abnormalities in genetics

Someone qualified that statement to the nearly meaningless point, so I marked it for snippage. Brewhaha@edmc.net 15:38, 12 August 2007 (UTC)

heavy metal poisoning hypothesis - expert attention needed ?

This seems to be a newer addition to the article. Perhaps someone with expertise on prions should review this section. Additionally, I'm not sure if this is poor wording, but the phrase It also follows from his work that carnivorous animals may be hazardous, is odd. Hazardous or at hazard? W. B. Wilson 05:13, 1 September 2007 (UTC)

You asked for an expert. The section should not name him or his opinions, and I think we want someone to speak for him. Apparently, he wants to guard and demonstrate whatever opinions he has, rather than be explicit. If he is in a citation, that is fine. I find it unlikely that he meant to remove the only external citations that were in the debate. 216.234.170.71 (talk) 05:38, 29 July 2009 (UTC)

References

Are a bit muddled. Can people stick to citing the most authoritative/original/useful reference for key topics, i.e. the way that a scientific publication would be referenced. I did a thesis on prions so I have most of the necessary references and I'll try to reorganise them but I'm not very good at wiki-speak!! Purple 22:04, 16 January 2008 (UTC)

A nifty tool for that is here. Plug in one number from a pubmed search and it'll grab the rest. BrewJay (talk) 23:03, 4 July 2008 (UTC)

"N - Concentration?"

What is this about sterilizing with "1N NaOH". I've never seen this notation before. I read the reference (#37 at time of my writing this) and indeed they use "1M NaOH" sometimes and "1N NaOH" other times. If it is an esoteric notation, I think we should point to an article about it or clarify it somehow. If it is a typo (perhaps it was a typo in the original reference) then it should be corrected as well. 75.34.53.200 (talk) 19:28, 23 March 2008 (UTC)

The "N" refers to normality, a common notation for concentrations of chemical compounds that may dissociate in solution. -- Ed (Edgar181) 19:41, 23 March 2008 (UTC)

I don't care what N means in this context. It's ambiguous, just as M is. Spell it out, especially the first time. One mol per litre. BrewJay (talk) 09:06, 10 June 2008 (UTC)

Viral hypothesis - dubious logic

Evidence in favor of a viral hypothesis include:

• No bacteria or other living organisms have been found in prion-affected organisms, defaulting to the idea that a virus must be involved

In the "Viral hypothesis" section, I tagged the above with {{dubious}} with this html comment:

does not logically follow: lack of bacteria etc does not "default" to presence of a virus. Can just as well default to a protein cause. Is this a wrong summary of the cite? The cite is: Baker & Ridley (1996). Prion Disease. New Jersey: Humana Press. 0-89603-342-2. -84user (talk) 02:55, 23 May 2008 (UTC) (fixed my italics -84user (talk) 03:02, 23 May 2008 (UTC))

lack of proof is not proof of innocence, in science you cnnot simply 'default' back to the theory that best suits you but instead must consider all angles until conclusive proof exists! (well pointed out) A.guinness (talk) 01:07, 27 May 2008 (UTC)

The assertion of "defaulting to a virus" is somewhat ridiculous, and absolutely does not follow. I removed that part of the sentence without ceremony or prejudice. – ClockworkSoul 01:38, 27 May 2008 (UTC)

{{relevance}}

I can see how genetics might be relevant to understanding whether it is true that protein can transmit deformations in protein, and when it mentions other manifestations of protease resistant protein and spongiform encephalopathy, I lose track of the point. Those topics are too jeneral. They hav their own articles. If you're interested in the whole category, fine, but this article isn't a category. BrewJay (talk) 20:11, 4 July 2008 (UTC)

Not sure how to interpret results.

In dietary requirements, Manganese is in the microgram range and Copper is in the milligram range, so Brown's hypothesis that it's easier to get an overdose of Manganese than Copper makes perfect sense. What doesn't make much sense is that protease resistant protein found in amyloid (something like scar tissue) is of the sheet variety, and Copper ions increase the proportion of that. Are there other examples of where in-vivo effects and in-vitro effects contrast? BrewJay (talk) 22:34, 4 July 2008 (UTC)

Please Dump Alphabet Soup

C'mon, guys. After I made this thing readable, in come abbreviations to replace understandable terms with things that are neither pronouncable nor easy to type. My grammer and style checker can do nothing with new words. I can't even tell it that they're nouns. PrP is an abbreviation for three words. You can also say "diseased prion" or "cellular prion". For variety and the art of being understood and remembered, it's also nice to say "sheet prion" or "helix protein" once you've established what those mean. I don't mind introducing abbreviations, but using them throughout the text makes this stuff look like some ugly version of math. BrewJay (talk) 00:22, 5 July 2008 (UTC)

jaked 122

wow, the removal, or should I say crossing out of the genetics section seems to be useless, as that is a real reason for prions to form. —Preceding unsigned comment added by Jaked122 (talk • contribs) 16:00, 5 July 2008 (UTC)

Think of a vulture. Why do you think it looks that way? It doesn't eat water-rich foods. If you eat something that's dried and dead, guess what you're going to look like? I'm only half kidding on this point. --Anthony Robbins.

You should identify an aburdity in the old saw that you are what you eat. If you eat a chicken, then you will not grow wings. If you eat fish, then you will not grow a sail fin and gills. You do not get genes from what you eat, yet Gajdusek has made this disease cross the species barrier with carefully orchestrated food. 216.234.170.107 (talk) 22:01, 21 July 2009 (UTC)

Prions for warfare?

So here is a conspiratorial thought. Are prions covered by the Biological Weapons Convention? or the Chemical Weapons Convention?Mrdthree (talk) 12:42, 10 December 2007 (UTC)

I know how paranoid I am, but could this ever be used for biological warfare?

Lunakeet 21:35, 29 July 2008 (UTC)

Perhaps your question would elicit a more detailed response on the science reference desk? It's a little off topic for a talk page.--VectorPotential Talk 21:38, 29 July 2008 (UTC)

That is the second time I read something like that, and it is wrong, because the reference desk is too heavy. It is better to put both the question and the answer before people who ought to know because they want to know. If bovine brain is a vector, then you will understand why many Japanese people were not pleased when they were shipped an entire cow from North America, and that is why Gajdusek is prominent among researchers. His evidence, and there is a lot of it in many different species from Mink to Hamsters, with homogenized brain tissue says that it is a vector. Using this for a weapon demands both infiltration of the vector and misinformation about it. I do not know if that lets it qualify. I am not a lawyer. That makes me happy. 216.234.170.75 (talk) 14:10, 16 July 2009 (UTC)

prions in Blood Stream?

I don't have the time to read the whole article, but: Are prions not only in the brain but in the circulatory system as well? —Preceding unsigned comment added by Dale S. Satre (talk • contribs) 17:55, 1 September 2008 (UTC)

Prions (assuming you mean the infectious prion particle) have been documented in the nervous tissue as well as muscle tissue. i am not sure if they have been documented in the bloodstream. it has been hypothesized that prions move through the nervous system to the muscle tissue, bypassing circulation for that particular route.

Jesse.maegan (talk) 02:07, 20 September 2008 (UTC)

Yes prions are present in the blood stream. Several people in the UK have contracted variant CJD after receiving a blood transfusion from a person who had been infected. Purple 21:27, 29 March 2009 (UTC)

Selection

Do the prions attack random neurons, or are the cells they attack predetemined (specific)? --Dale S. Satre 18:13, 1 September 2008 (UTC)

The basis of prion infection is that (PrP^SC) converts the endogenous prion protein (PrP^C) into the infectious form. The endogenous prion protein has been found widely dispersed in a variety of tissues, but regarding nervous tissue, the hippocampus appears to be most heavily affected. In addition, there is convincing evidence for PrP^C localization at the synaptic junction (neuron-neuron as well as neuromuscular). Essentially, any cell containing PrP^C can be affected by PrP^SC.

Jesse.maegan (talk) 02:11, 20 September 2008 (UTC)

Good answer. In sum, not random. Random, adj.: Following a pattern beyond your understanding.216.234.170.107 (talk) 21:53, 21 July 2009 (UTC)

Only known disease?

Regarding the line "Prion diseases are the only known diseases that can be sporadic, genetic, or infectious," isn't cancer another such disease? Its Wikipedia page clearly includes all three of those transmission types as well. Perfundle (talk) 23:01, 27 March 2009 (UTC)

I would agree that cancer probably fits those criteria as well. This statement is dubious. Prionpersona (talk) 18:29, 29 March 2009 (UTC)

I disagree - although there are types of cancer that can be genetic, sporadic or caused by an infection, they are all different conditions, involving different cells and tissues and processes. "Cancer" is a general classification, the same as "amyloid diseases" or "neurodegenerative diseases". The other important distinction is that even though there are some cancers that can be triggered by an infection, the cancer itself is not an infectious disease - the cancer cells aren't infectious. As an example, hepatitis infction can trigger liver cirrhosis, but you wouldn't call cirrhosis an infectious disease.Purple 21:25, 29 March 2009 (UTC)

I concur with purple. A Swiss or Swedish study (should I look that up?) could find no relation between blood transfusions and cancer, so cancer is not infectious. Infectious is a poor word for disease that transmits only through food designed for the purpose of propagating disease. 216.234.170.107 (talk) 21:13, 21 July 2009 (UTC)

New study linking severe C.F.S/M.E. and Prions?

Dr. De Meirleir just published the results of a study on severe, bedridden M.E. patients in Norway. He presented his findings last week at a conference in London.

My question is, should the possible connection to CFS be mentioned on this Wikipedia article on Prions? If so, where would it fit in?

Here are the links to his presentations and summary of his study:

[9]

Thanks!

Kosovokelly (talk) 10:35, 7 June 2009 (UTC)

We can't use conference reports as sources, we have to wait until the findings are published in a reputable journal. Also, unless the findings draw attention from other authors, the results of a single clinical study would normally be considered a primary source that ought not to be used according to WP:MEDRS. In short, we need more validation in order to use something like this. Looie496 (talk) 17:50, 7 June 2009 (UTC)

That link to prohealth looks like commercial fearmongering to sell a test for H₂S in intestinal microflora that can, in serious cases, propagate to the bloodstream. I can not say that the test is totally without merit, because our liver normally protects us from microfloral emissions. It does not say anything about what you can do about it. In sum, the article invokes all of the modern enemies in Biochemistry, and conflates them, so I would not like to see it used as a reference here. 216.234.170.107 (talk) 21:49, 21 July 2009 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Prion/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

A Whether cause, effect or both, I think even the way the article has developed is an example of how collaboration can make a broad and understandable introduction to a topic as difficult to understand as a biochemical one. Brewhaha@edmc.net 09:49, 8 May 2007 (UTC)

Last edited at 09:49, 8 May 2007 (UTC). Substituted at 21:56, 3 May 2016 (UTC)