A recent study by David Denhardt and team, from Rutgers University, suggests that weightlessness may be bad for the immune system. The study showed that simulated weightlessness caused the spleen and thymus organs to decrease as much as 70% in size. These organs are responsible for triggering the creation of white blood cells in the body. White blood cells in turn destroy diseased cells and invaders that are in the blood stream. The decrease in size of the spleen and thymus organs was connected to an increase in the hormone called osteopontin (OPN).

The weightlessness was simulated by lifting up the mice's hind legs. I'm not sure how this was decided to be an accurate depiction of the effects of weightlessness - it seems a little fishy to me. But perhaps there is tons of science behind the method. For instance, Osteopontin has been connected with the bone loss that occurs in space.

By using a powdered extract from a pig bladder, it may be possible to regrow parts of fingers. This could help people who have lost fingers in fires, explosions, or doing not very bright things. While it has not been scientifically verified that the pig bladder extract is solely responsible for the regeneration, the compound has been approved by the FDA for use in humans. Currently the compound is used to help horses regenerate ligaments.

The basic function is well written in the AP article, "The powder is mostly collagen and a variety of substances, without any pig cells, said Badylak, who's a scientific adviser to ACell. It forms microscopic scaffolding for incoming human cells to occupy, and it emits chemical signals to encourage those cells to regenerate tissue, he said."

Panasonic has developed a prototype exoskeleton that uses compressed air to help the wearer move limbs. The device is designed to help people with partial paralysis regain use of a bad limb. It functions by using sensors on the elbow and wrist that control eight compressed air 'muscles'. A picture is available at Cnet

Four people in the United States have had this bionic-arm surgically attached. The arm is capable of sending touch sensations to the wearer, so that if a person is touched by another person's hand the wearer will feel the sensation. I would assume that the wearer would also be able to feel objects that the arm comes in contact with. The arm articulates elbow and finger movements based on impulses from the wearers brain. In plain English, if the wearer thinks about moving their elbow - the elbow will move.

The device was surgically implanted at the Neural Engineering Centre for Artificial Limbs at the Rehabilitation Institute of Chicago. They use a process called targeted muscle reinnervation, which involves removing certain nerves from the chest and re-purposing them for use in the prosthetic arm. This is accomplished by taking the nerve fibers from the chest and attaching them to the remaining nerves in the arm. Myoelectric-Sensors then detect nerve impulses that would go to the arm and articulate the prosthetic accordingly.