Happy Thanksgiving week to the American readers! In celebration, let's talk gout!
Uric acid is the final product of purine (the bases that comprise exactly half of your DNA) catabolism in humans. Normally, you urinate it out with no problems. Below are guanine and adenine (the two purines that are found the vast majority of the time in vivo) and their metabolite, uric acid:
However, it's rather insoluble, so if you've got too much hanging around, problems arise. It can deposit in various parts of the body, notably (in most first attacks) in the big toe.
Gout is as puzzling as the rest of purine metabolism and probably comes from a bunch of causes. Until relatively recently, it was considered a disease of "overindulgence," and blamed on consumption of too much rich food and drink. Many of these are rich in purines (beer and organ meat such as liver are two examples every biochemistry book seems to cite), and a purine-limited diet seems to help some sufferers, but metabolism is rarely so simple. Some gout sufferers make too much purine de novo (i.e., not from food), some have trouble excreting it.
Another obligatory note on gout is the cartoon that seems to be in every single textbook. I didn't know why until I looked at the Wikipedia article - it's public domain! There's still an interesting story. The author, Briton James Gillray, was famous in his own time (spanning the late 18th and early 19th centuries) for his work as a satirist and caricaturist. Late in his life, his eyesight failed. The last ten years of his life weren't so bright - he attempted suicide, succumbed to alcoholism, and spent his last years under care for mental illness (not to mention gout- he was a sufferer himself).
James Gillray's The Gout:
Interestingly, primates are one of only a few animals for which uric acid is the final product of purine metabolism - just about everything else takes the metabolism a few steps further. Check back in a few hours for a drug treatment of gout.
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Beer is an organ meat?? That will make the boys at USDA sit up and take notice. (for the noncognoscenti; in the US meat and meat products are inspected by the Department of Agriculture while other food processing facilities are regulated by the Food and Drug Administration. This can lead to interesting definitions. Is a frozen pepperoni pizza a meat product? The last one I purchased had a USDA inspection seal on it.)
Clarified.
I didn't know we could make uric acid at all. Thought everything with nitrogen got broken down to urea. Uric acid is the preferred way for birds to get rid of nitrogen, the white stuff in their feces is uric acid. Would be interesting to know why we don't excrete all nitrogen as uric acid as opposed to urea. Uric acid is more expensive to make, but for mammals with little access to water I'd guess it could be nice to excrete uric acid with the feces as opposed to urea with urine. And why uric acid with the urine and not feces?
Guess I need to read my biochemistry book better...
There's also the Dialogue between Franklin and the Gout.
Yeah, I thought most mammals, including primates, excreted urea, while fish (with the exception of sharks) excreted ammonia, and reptiles and birds excreted uric acid. The reason being is that ammonia is more toxic than urea which is mor toxic than uric acid. Dillution is no problem for fish who live in water, and birds need to be as light weight as possible so they need the least toxic one so they don't have to dillute it as much.
Is uric acid a purine? Is it like vitamin b4?
This is a good depiction of how my foot feels notice the sharp sharp teeth imagine gnawing sensation accompanied by the prickly pain and notice the fire breath coming out of the noise yes.yaaaaaaaaaaaaaaaaaaaaaaaaaaaaaah help me
4-real.