Khamis, Februari 13, 2014

World’s most deadly mushroom smells delicious, is invading every continent

Death Cap

You can tell just from the name that a Death Cap mushroom is not something you ought to eat. However, this fungus is spreading rapidly across the globe and it looks and smells a lot like a number of edible species of mushroom. With people being poisoned and even killed by this mushroom, a lot of work has gone into finding a way to counteract its effects. Doctors may be close to finding a solution, but first victims of the Death Cap have to be identified.
Amanita phalloides, as the Death Cap is more properly known, is stupendously toxic to humans. As little as 30 grams of it can result in death, and it can be hard to even diagnose patients properly in time.
After eating a Death Cap mushroom, a person will usually feel no discomfort for 6-24 hours. At that point, nausea, vomiting, and other GI tract issues will set in. The delay makes it hard for doctors to connect the symptoms to mushroom ingestion. Patients are often given hydration therapy to treat a simple stomach bug, but that only delays the inevitable.
Alpha-amanitin structure
The key to preventing fatal Death Cap poisoning is in counteracting its main toxic compound, which was isolated decades ago. After ingestion, a substance called α-amanitin makes its way to the liver and kidneys. This compound binds up and inactivates an enzyme in cells called RNA polymerase II, which makes messenger RNA and is an integral part of proteinsynthesis. With no protein synthesis, cellular metabolism stops and the cell dies. The digestive tract recycles this toxin through the liver over and over, eventually leading to organ failure.
As humans have become more mobile, we’ve been spreading the spores of Death Cap mushrooms around the globe with plants and soil. Like many similar fungi, Amanita phalloides lives symbiotically on the roots of certain trees. The Death Cap is finding its way into the diets of more people largely because it has proven to be very adaptable by gaining the capacity to live in harmony with more tree species. Places where all the similar-looking mushrooms were once safe are now peppered with colonies of super-deadly Amanita phalloides. Originally native to Europe, the Death Cap is now on all continents, except Antarctica — feel free to eat any mushrooms you find there.
Death Cap 2
A clinical trial of a new compound called silibinin is showing promise. Silibinin is isolated from milk weed thistle and when ingested, blocks the receptors that absorb Death Cap toxins in the liver. This keeps α-amanitin in the blood where it can be more efficiently filtered out by the kidneys. 60 patients with Death Cap poisoning have been saved by silibinin so far, but getting to the proper treatment in time is still a challenge. If Amanita phalloidescontinues popping up in more places, doctors might have to get better at figuring it out. -Geek

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