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I withdrew some money from the bank so I would have some cash in my wallet. I also did a little work in UVA's Cocke Hall. Back at my house, Karen the German Girl and Cecelia the Brazilian Girl had just woken up. They fixed some strange spaghetti for us three to eat. We didn't have much red stuff to work with for sauce, so we taxed a little from the various containers belonging to my housemates that we found in the refrigerator. I was feeling sleepy, so I took a nap. The girls went off to do other things.
I slept again; this time until 1:01 am. My alarm was set overly quiet for some reason. I made it to work maybe ten minutes late. I'm almost never late. But unlike certain others on the staff here at Comet, I feel bad about it and intend to make up for it. I'm pretty used to those who are supposed to spell me coming to work late and thinking nothing of it.
Earlier in the evening I'd been listening to an interesting installment of National Public Radio's Living on Earth. It's a weekly news magazine about environmental issues. Two issues that struck me were:
Unlike viruses and living creatures, prions cannot be destroyed by conventional cooking or ultaviolet light. Any process that can successfully destroy prions would also destroy the meat containing them.
Prions are fascinating from a biological perspective since they have the power, in some very special environments, to reproduce. They do this without any genetic material like RNA or DNA. Instead, by their very shape, they somehow are able to catalyze the transformation of good PrP into prions. But unlike true reproduction, the new prions will only adopt a mother-prion's shape, not a mother-prion's amino-acid sequence. Interestingly, prions from one species can catalyze the formation of prions in another. The efficiency of such trans-species catalysis appears to be related to the similarity of the amino acid sequences in the PrPs of the respective species. The greater the similarities in the middle sections of the respective PrP proteins the greater the capacity for trans-species prion propagation. Thus sheep prions can catalyze prion formation in cows, whereas they cannot catalyze prion formation in humans. It is important to remember, however, that once prions are being formed in a new species, they carry the amino acid sequence of that species' PrP and thus can have new trans-species infectious characteristics. So, while it may be safe for humans to eat sheep containing high prion concentrations, it is not safe for cows to do the same and it is not safe for cows to eat cows or sheep to eat sheep (strangely enough, in the modern farming industry, such cannibalism is actually rather common; more on that later).
Okay, so it is safe for us humans to eat sheep. But what about humans eating beef? The answer appears to be that beef prions can cross the species barrier to humans. More on that later too.
But where do prions come from originally? In certain people (about one in every million), the genes that code for the PrP have a mutation that makes their PrP especially susceptible to reconfiguration into prions. Either tiny amounts of sufficiently infectious prions in such people's diet or spontaneous reconfiguration eventually leads to an accumulation of prions, followed by human spongiform encephalopathy, called Creutzfeldt-Jakob disease. Usually such cases do not manifest until the susceptible person is in their 60s or older.
But the modern farming industry has inadvertantly caused the "background" prion concentrations in domesticated animals to enter into an amplification loop facilitated by cannibalism. Modern day animal processing plants recycle waste parts of carcasses back into the farm animal food supply. Low levels of prion concentrations in beef and sheep are fed to other sheep and cows, where they facilitate the creation of yet more sheep and beef prions. These in turn are fed to other sheep and cows. On and on it goes. In Britain, this has led to massive outbreaks of sheep and bovine spongiform encephalopathy (Mad Cow Disease). This has jumped the species barrier to infect cats and even zoo animals through commercial beef and sheep-based animal food preparations.
This would only be an animal tragedy were it not for the fact that bovine prions can, in some cases, reach high enough concentrations in humans neurons to facitate the conversion of human PrP into prions, leading ultimately to human spongiform encephalopathy, or Creutzfeldt-Jakob disease. It's a horrible disease, characterized by slowly escalating dementia and ultimately death. What's particularly eerie about Creutzfeldt-Jakob disease is the fact that it can take as long as 30 years to manifest itself. Already, in England, there have been outbreaks of Creutzfeldt-Jakob disease that can be attributed to the eating of beef. Now people wait anxiously to see who will be felled by the disease next.
And we're not immune to this problem in America. Like most countries, we feed cows the unused remains of other cows. And we eat lots of beef here too. The beef industry has a lot of clout in this country (as they did in England), and they have yet to change any of the factors that facilitate prion accumulation.
I delayed eating my beef and ramen soup. But eventually hunger set in and so I prepared it and ate it. The number of prions in this evening's meal are no doubt a drop in the bucket of my lifetime supply so far.
Mad Cow Disease: Much More Serious than AIDS - this article is good and scary.
Prion Disease - this is the fascinating story of prions from the guy who coined the term.