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Year in space put US astronaut's disease defense on alert



WASHINGTON (AP) – Nearly a year in space put astronaut Scott Kelly's immune system on high alert and changed the activity of some of his genes compared to his Earth-bound identical twin, researchers said Friday. NASA twins study, which has raised new questions for doctors as the space agency aims to send people to Mars

Tests of the genetic doubles gave scientists a never-before opportunity to track details of human biology, such as how an astronaut's genes turn on and off in space differently than at home. One puzzling change announced Friday at a science conference: Kelly's immune system was hyperactivated

"It's like if the body is reacting to this alien environment sort of like you would be a mysterious organism inside you," said geneticist Christopher Mason of New York's Weill Cornell Medical College, who helped lead the study. He said the doctors are now looking for that in other astronauts.

Since the beginning of space exploration, NASA has studied the toll on astronauts' bodies, such as bone loss that requires exercise to counter. Typically they are in space about six months at a time. Kelly, who lived on the International Space Station, spent 340 days in space and set a U.S. record

"I've never felt completely normal in space," the now-retired Kelly said in an email to The Associated Press, citing the usual congestion from shifting fluid, headaches and difficulty concentrating from extra carbon dioxide and digestive complaints from microgravity

But this study was a unique dive into molecular level, with former astronaut Mark Kelly, Scott's twin, on the ground for comparison. A number of genes linked to the immune system have become hyperactive, Mason said. It is not a change in DNA but in what is called "gene expression," how genes turn off and on and increase or decrease their production of proteins. Mason also spotted a spike in the bloodstream of another marker that primes the immune system. Yet at the same time, Kelly's blood showed fewer of another cell type that is an early defense against viruses

"It is not surprising that gene activity would change in space ̵

1; it changes in response to all sorts of stress. "Good news: Most of everything returned to normal shortly after Kelly got back on Earth in March 2016. Those immune-related genes, however," seemed to "It's all encouraging," said Craig Kundrot, head of space life and science research for NASA, "said Mason.

"There are no major new warning signs. (19659002) From four Russians living in space for more than a year, NASA has already known a prolonged time off Earth is possible, Kundrot said, adding "We also aim for more than just possible. We want our astronauts to do more than just survive. "

Finally, the twins study gives NASA a catalog of things to monitor on future missions to see if other astronauts react in the same way. Astronauts on future missions will be able to do some of this testing in space instead of freezing samples for scientists back home, Mason said.

Immune issues sound familiar to Dr. Jerry Linenger, an American astronaut who spent more than four months on Russian space station Mir. He said he was never sick in the orbit, but once he came back to Earth "I was probably more sick than I was in my life."

Astronauts launch into orbit with their own germs and get exposed to their crewmates' germs and NASA hopes to launch in the 2030s, "said Linenger.

A human mission to Mars, which NASA hopes to launch in the 2030s, will take 30 months, including time on the surface, Kundrot said.

Radiation is a top concern. The mission would expose astronauts to galactic cosmic radiation levels higher than NASA's own safety standards. It's just a little bit over, "he said.

On Earth and even on the space station, Earth's magnetic field shields astronauts from lots of radiation. There was no such shielding on the way to Mars and back, but tunnels or dirt-covered habitats might help a bit on Mars, Kundrot said

Kelly, who turns 55 next week, said he would go to Mars. He said a trip that long would not be worse than what I experienced. Possibly better. I think the big physical challenge, radiation aside, will be a mission where you are in space for years. "

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Department of Science Education.

The AP is solely responsible for all content.
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