Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Prions

countere.com

Post reply on HN
Print view View original

161–170 of 184 posts

Re: Prions

#161

Post by lazide »

Scandiravian wrote: post #78
im3w1l wrote: post #60

Earlier quoted context omitted.

In order to evolve there has to be some kind of genetic information passed on to descendants. But for prions there is no such mechanism. A lower energy state is assumed and that's that.

So prions are simply a result of entropy? Am I understanding that correctly?

All evolutionary change (and life itself) is due a combination of differences of entropy (aka an energy gradient existing), combined with randomness in the current environment allowing mutation/change and hence selection pressure.

Re: Prions

#162

Post by Ericson2314 »

Scandiravian wrote: post #78
im3w1l wrote: post #60

Earlier quoted context omitted.

In order to evolve there has to be some kind of genetic information passed on to descendants. But for prions there is no such mechanism. A lower energy state is assumed and that's that.

So prions are simply a result of entropy? Am I understanding that correctly?

I would say life is an artifact of non-erodicity. Rare things that self-replicate are over-abundant in hindsight.

Re: Prions

#163

Post by incrudible »

mannerheim wrote: post #118
incrudible wrote: post #16

I remember that in the 90s, when "mad cow disease" was dominating the headlines, it was predicted that there would be an exponential increase in cases, decades down the line. The same point about prions being virtually indestructible was being made, the same concerns about surgical equipment and blood donations were raised. Suffice it to say, the prion disaster did not materialize, so I'm skeptical about the same sto…

It isn't really possible to prepare beef in a way to eliminate prions; you have to just make sure the beef you're preparing doesn't have them.

I'm aware that prions are hard to destroy, but that's a different question as to whether they are contagious. A lot of contaminated beef did enter the food chain, yet the expected surge in vCJD did not occur. I would expect cooking to have some impact here, but that's just a guess.

Re: Prions

#164

Post by Ericson2314 »

hannasanarion wrote: post #100
enchiridion wrote: post #81

Earlier quoted context omitted.

There does not have to be genetic information for evolution. Evolution only requires "descent with modification". DNA is a mechanism for this, but it is not necessarily the only one.

And prions don't have descent with modification. It's a regular mammal brain protein that got accidentally constructed backwards. There's nothing to pass on, nothing to modify.

descent without modification sounds pretty hard to achieve for all but the simplest things.

Re: Prions

#165

Post by mgarfias »

dnautics wrote: post #59
cogman10 wrote: post #11

Earlier quoted context omitted.

What do you make of CWD? That one scares me more than current known human prion disease. Mainly because it seems to spread really easily. Other prion diseases seem to practically require cannibalism to spread.

Cwd is essentially the same as bse and cjd and scrapie. It's actually the one that you have to worry about the least. For unknown reasons, there is not species crossover between deer and cow/sheep/humans (I was briefly investigating the molecular mechanisms for this but finished my phd before getting results). As for why the grazing animals can spread prion, my guess is that the prion protein is highly concentrated i…

But lenguas?!?

Re: Prions

#166

Post by chasil »

dnautics wrote: post #70
danesparza wrote: post #64

Earlier quoted context omitted.

Wait, wait, wait. Your advice seems contradictory: "there is not species crossover between deer and cow/sheep/humans" and "Incidentally, you probably shouldn't eat beef tongue." Can you clarify?

Sorry, the grouping was unclear. There is not deer sheep, deer cow, deer humans. There is cow sheep, maybe cow human. I don't know off the top of my head about sheep human If there had been, the us food supply would be trashed. Cwd is highly endemic among wild deer and wild deer co-graze with cows all the time. Also unknown if the relationship can be transitive. There might be a species X where deer X human.

Scrapie appears to have been the ultimate cause of a human CJD outbreak:

"...in 1996, with the recognition in young people in Britain of a “new variant” of Creutzfeldt-Jakob disease (nvCJD, or the Will-Ironside syndrome) that has since been traced with near certainty to the consumption of tissue from cattle infected with spongiform encephalopathy (BSE), they having in turn consumed meat and bone meal contaminated with rendered sheep carcasses infected with scrapie... There are currently just over 30 verified cases of nvCJD, and four to five new cases a year: whether they represent a small group of susceptible people or are the leading edge of a major epidemic is still moot."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114482/

Re: Prions

#167

Post by im3w1l »

DetroitThrow wrote: post #136
hannasanarion wrote: post #100

Earlier quoted context omitted.

And prions don't have descent with modification. It's a regular mammal brain protein that got accidentally constructed backwards. There's nothing to pass on, nothing to modify.

Err, I think I remember a couple pretty famous articles that contradicts that prions generally don't have descent with modification, which may be what the person above us is referring to: https://pubmed.ncbi.nlm.nih.gov/20044542/ https://pubmed.ncbi.nlm.nih.gov/17142317/

That's really neat. Still there should be a limited number of possible variants right? Like the energy landscape is fixed and will only admit so many possibilities?

Re: Prions

#168

Post by chasil »

hajile wrote: post #142
incrudible wrote: post #16

I remember that in the 90s, when "mad cow disease" was dominating the headlines, it was predicted that there would be an exponential increase in cases, decades down the line. The same point about prions being virtually indestructible was being made, the same concerns about surgical equipment and blood donations were raised. Suffice it to say, the prion disaster did not materialize, so I'm skeptical about the same sto…

Who knows. I'll give you an interesting thought. There is NO single, conclusive test for Alzheimer's disease. The symptoms are almost identical to CJD (human mad cow) with the biggest differentiator being time from diagnosis to death. Even Amyloid-beta plaque buildup is often (though not always) noted in CJD patients [0][2]. Likewise the other Alzheimer's marker tau protein is also elevated in CJD patients [3]. I'd n…

Here is another major difference:

"We know that the β-A4 amyloid of Alzheimer’s disease also derives from a normal host protein that in diseased people accumulates in the brain, but it does not have the ability to transmit disease to a healthy person. Why this difference?"

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114482/

Re: Prions

#170

Post by eximius »

chasil wrote: post #146
nikartix wrote: post #79

Earlier quoted context omitted.

How old are these proteins? If the do spread and remain dormant in soil they would have been a threat for entire existence of life on this planet. Exponential growth would only cause every place, especially a bio-reach locations to be full of it as food chain making more and more of the protein and animals remains are not handled in any way in the wild.

It appears that the first mention of scrapie in scientific literature is 1755, and the disease increased with inbreeding (and lessened when this practice was stopped): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114482/ The wiki also indicates that a sheep vaccine distributed in 1935 caused an epidemic, as it contained contaminated neural tissue: https://en.wikipedia.org/wiki/Scrapie It also seems to me that the re…

This is a very interesting idea! But, is it known that macrophages are able to break down prions? My understanding of the problem is that part of it is that they're just quite hardy.
Post reply on HN