Mr Isotope

'THE MIRACLE CURE'
A thin, corrugated pipe ran deep below the giant superstore, pumping excrement from its customer toilets directly into the man's anus. Three years (not that time had any meaning now), encased in concrete about sixty feet underground and unable to move, all senses failed and eyes sealed over; most vital organs still functioned, though his brain was numb and his intestines worked in reverse. His skin however had been chemically eroded as the concrete set, but was no longer necessary - replaced by the same embalming concrete.
A second, shorter pipe exited his body just below the larynx and led to a small chamber with enough air to sustain functionality for a good ten years at his level of inactivity before carbon dioxide concentration and oxygen depletion took him into an ever-deepening coma.
The third pipe carried the processed sewerage from his mouth back to the surface and to a nearby fast food restaurant. As the effluent passed backwards through his digestive tract it picked up nutrients from the man's gradually wasting body. When the product reached the surface, some of it was mixed with rusk and a (necessary) laxative and added to their burger mince. The rest was chilled and used as a base for their milkshakes.
Of course the supermarket chain and the burger chain were owned by the same corporation. Around the World their supermarkets, burger bars and filling stations stood out as pristine islands dotted about the surface of an otherwise diseased and rotting planet.
Deep within the man's entombed mind, a thought or memory would sometimes flicker momentarily, futile like the lonely spark of a damp match struck desperately in the hopeless pitch darkness of a cave. A bad habit: "It doesn't do to dwell". But that tiny, betraying flame of life would flicker, torturing his remains with distant nostalgia, unattainable longings, unamendable regrets, old dead world.
Yet he knew he was probably one of the lucky ones. It didn't matter that he wasn't on the surface; even before his employment he was stuck - couldn't get back since they took his car away.
A few thousand miles away, a central computer kept a record of his bank balance as it grew by tiny weekly increments, his wages, the whole business completely automated.