Professor Stephen Hawking has toured a US stem cell laboratory where scientists are studying ways to slow the progression of Lou Gehrig's disease, a neurological disorder that has left the cosmologist almost completely paralysed.
After the visit, Prof Hawking, 71, urged doctors, nurses and staff at Cedars-Sinai Medical Centre in Los Angeles to support the research.
He recalled how he became depressed when he was diagnosed with the disease 50 years ago and initially did not see a point in finishing his doctorate. But his attitude changed when his condition did not progress as fast and he was able to concentrate on his studies. "Every new day became a bonus," he said.
The hospital received nearly 18 million dollars last year from California's taxpayer-funded stem cell institute to study the debilitating disease also known as amyotrophic lateral sclerosis. ALS attacks nerve cells in the brain and spinal cord that control the muscles. People gradually have more and more trouble breathing and moving as muscles weaken and waste away. There is no cure and no way to reverse the disease's progression. Few people with ALS live longer than a decade.
Diagnosed at 21 while a student at Cambridge, Prof Hawking has survived longer than most. He receives round-the-clock care, can only communicate by twitching his cheek, and relies on a computer mounted to his wheelchair to convey his thoughts in a distinctive robotic monotone.
A Cedars-Sinai patient who was Prof Hawking's former student spurred doctors to invite the physicist to glimpse their stem cell work. "We decided it was a great opportunity for him to see the labs and for us to speak to one of the pre-eminent scientists in the world," said Dr Robert Baloh, who heads the hospital's ALS programme.
Cedars-Sinai scientists have focused on engineering stem cells to make a protein in hopes of preventing nerve cells from dying. The experiment so far has been done in rats. Dr Baloh said he hopes to get governmental approval to test it in humans, which would be needed before any therapy can be approved.
Renowned for his work on black holes and the origins of the universe, Prof Hawking is famous for bringing esoteric physics concepts to the masses through his best-selling books including A Brief History Of Time, which sold more than 10 million copies worldwide. He called his speech to Cedars-Sinai employees A Brief History Of Mine.
Despite his diagnosis, he has remained active. In 2007, he floated like an astronaut on an aircraft that creates weightlessness by making parabolic dives.
Doctors do not know why some people with Lou Gehrig's disease fare better than others. Dr Baloh said he had treated patients who lived for 10 years or more. "But 50 years is unusual, to say the least," he said.