Aviyara
Aviyara t1_iwh5rpu wrote
Reply to comment by scheav in We have seen successful transplants of various organs, hands, even faces -- so why not transplants of legs or feet to lower-limb amputees? Why are these not a thing? by Pandeism
The three largest causes of death in solid-organ allografts (organ transplants) are cancer (which most immunosuppression courses are well-documented as increasing the incidence rate of), graft rejection, and infection.
I would not call any of these "unrelated causes." An allograft recipient is on immunosuppression for life.
You are correct, the prognosis of an allograft recipient gets better every year. This is not because allograft care in the late 20th century was spectacularly bad, and we're just making up for that statistical anomaly.
The first double-lung transplant recipient famously had her lungs outlive her.
Meanwhile, 41% of all lung transplant recipients in 2010 were dead by 2015.
Aviyara t1_ixm8wt1 wrote
Reply to I am currently writing an essay on prions. Prions are quite specific microorganisms so there is a lot of information about them on the Internet, but not everything. That's why I ask myself here - why are prion diseases incurable? by kirsiuu
Imagine you were a sword-smith in Ye Olden Days. Your smithy makes excellent swords: straight, solid bars of steel with sharp edges, nothing special or odd about them.
One day, one of your apprentices brings in a new hammer he got from a sorceror on the edge of town. He takes a hot bar of steel from the forge and gives it a whack with the hammer.
The bar, which was this shape: |
transforms into this shape: ›
...and immediately becomes powerfully magnetic.
That magnetism wrenches it free of your apprentice's hand, and the bent bar of steel flies off through the air towards the sword in your hand.
They collide: ›|
and the impact, plus the magnetism, bends your sword to match: »
Your bent sword now also becomes powerfully magnetic. They both are drawn off into your shop, where you have many swords hanging on racks and shelves.
Chaos ensues.
-----------------
Prions are no more alive than steel or water are alive. They are proteins, twisted by luck into a terrible shape. It is their shape that makes them dangerous; that shape - like the magnet-swords above - bends any identical sibling-proteins they collide with, twisting them into that same cursed shape. And much like a sword bent into a magnetic wedge, they are also useless for their original purpose.
This is also why there is no cure: there is no living thing involved. Antibiotics are poisons tailored to kill bacteria - but prions don't eat. Antivirals keep viruses from entering a cell or block them from using cell machinery - but there's no cell involved here. This isn't a biology process - this is a physics process.
It would be like trying to make a drug that stops lava from melting rocks.