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Prions

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Re: Prions

#141

Post by wil421 »

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…

No lengua tacos? What will I get now?

Re: Prions

#142

Post by hajile »

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 note that we don't actually know that CJD must progress over 1-2 years rather than a decade -- it is an observational assumption.

Between 15-30% of Alzheimer's diagnosed patients also don't have the normal Alzheimer's brain symptom (presumably amyloid buildup) either. Alzheimer's as cause of death was 17.6% in 2000, but is now 37.3% in 2020.[1] Because CJD is defined as killing quickly, it isn't even checked for in such cases (a kind of self-fulfilling prophecy if the diagnosis criteria aren't actually accurate). It doesn't help that cleanup of a contaminated area is time consuming and costly (not to mention potential negative press and panic).

This isn't a new idea, but perhaps those fears were somewhat true, but have been buried under our lack of knowledge of protein diseases.

[0] https://pubmed.ncbi.nlm.nih.gov/3092727/

[1] https://alz-journals.onlinelibrary.wiley.com/doi/full/10.100...

[2] https://pubmed.ncbi.nlm.nih.gov/12891683/

[3] https://pubmed.ncbi.nlm.nih.gov/20881758/

Re: Prions

#143

Post by ggreer »

imglorp wrote: post #74
ggreer wrote: post #68

Earlier quoted context omitted.

If US beef was contaminated, wouldn’t there be thousands of cases of vCJD[1] by now? 1. https://en.wikipedia.org/wiki/Variant_Creutzfeldt–Jakob_dise...

Yes there could be. It remains latent for years after consuming the infected meat. Guess we'll find out! ¯\_(ツ)_/¯

We did find out. The US has had a total of 4 cases of vCJD, all of which were contracted overseas.[1] For comparison, the UK has had over 170 cases.[2]

1. https://www.cdc.gov/prions/vcjd/vcjd-reported.html

2. See table 3 in the PDF on this page: https://www.termedia.pl/Review-article-r-n-r-nVariant-Creutz...

Re: Prions

#144

Post by Scandiravian »

ortusdux wrote: post #91
Scandiravian wrote: post #72

Earlier quoted context omitted.

I think that's an interesting point. Do you have a source for your statement, that most of the research happens post mortem? It makes sense to me that non-lethal cases wouldn't be discovered, as it's probably prohibitively expensive to screen for non-lethal/dormant infections. It could also be that the progression is so slow for most people, that they die from unrelated causes before the disease becomes a problem (th…

The first promising blood test for mad cow (vCJD) was developed in 2016. Prior to that, "The only current method to diagnose vCJD is to perform a biopsy or a postmortem analysis of brain tissue." (NIH 2017). https://www.nih.gov/news-events/nih-research-matters/new-met... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5538786/ Scientists have since developed a promising method that relies on analyzing the retina. https:…

Thank you for the links - I look forward to reading the articles :-)

Re: Prions

#145

Post by ced »

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.

FWIW Wikipedia says:

> Prion replication is subject to epimutation and natural selection just as for other forms of replication, and their structure varies slightly between species.[19]

[19] is https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2848070

Re: Prions

#146

Post by chasil »

nikartix wrote: post #79
dnautics wrote: post #9

Earlier quoted context omitted.

This comment is spot on (I'm a former prion researcher).

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 recent mRNA vaccines could be repurposed to target a section of a prion, so the immune system could clean them from the blood. An interesting question would test mRNA vaccine effectiveness in the cerebrospinal fluid, where microglia would be required to perform this function, as macrophages (and friends) are not present there.

Re: Prions

#147

Post by Scandiravian »

bb123 wrote: post #101
Scandiravian wrote: post #55

Earlier quoted context omitted.

I think there's better arguments than a risk of prion disease for cutting beef (or meat in general) from your diet - not sure if your comment is meant as a joke that I'm not catching, so I'll hold out on going into details unless you're interested :-)

Not meant as joke. I'm aware that there are lots of good reasons for not eating beef, I was wondering if prion exposure risk is one of them, as the meat/no-meat argument is one I try to revaluate regularly as new info comes to light. I eat beef once or twice a week as I have found it hard to get sufficient iron, protein, b12 and enough calories in general without it (and other meats). That and it tastes good, but I'm…

I don't think prion disease currently is a significant enough risk to make it an argument against eating meat. It's a rounding error compared to for instance increase in colon cancer

I eat meat occasionally as well. I tried going vegetarian for a six months, but I lost an unhealthy amount of weight (my BMI dropped from 19.2 to 17.8) and I think the health risk from malnutrition, as you also mention having struggled with, is much more severe than that of prion disease

Re: Prions

#148

Post by [deleted] »

derekp7 wrote: post #47
beiller wrote: post #19

Earlier quoted context omitted.

If it was more deadly it would spread less quickly. That's how diseases work from my vague university memories of an epidemiology course. They are on a spectrum of deadly to contagious.

What actually causes this though? For example, take something like HIV that takes a long time to show symptoms, but have an airborne version of it. Do the things that make viruses airborne also keep them from having a long gestation period and also highly lethal?

[deleted]

Re: Prions

#149

Post by marcosdumay »

im3w1l wrote: post #76
marcosdumay wrote: post #62

Earlier quoted context omitted.

There's some space for prion evolution, but it's a very small set of possibilities. And more importantly, the little they can evolve, they do so at random, there is no genetic recombination step to merge the selection of unrelated features.

You misread me.

Oh, indeed I misread it.
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