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Simulations with animal models meant to reflect the astronauts' exposure to galactic cosmic rays draw the attention of investigators from the Georgetown University Medical Center (GUMC) on the health of astronauts on long journeys, such as Mars.
Their most recent study, published in the Proceedings of the National Academy of Sciences (PNAS), suggests that a deep space bombardment by galactic cosmic radiation (GCR) could significantly damage the gastrointestinal (GI) tissue, resulting in long-term functional alterations. The study also raises concerns about the high risk of developing tumors in the stomach and colon.
Their previous work had highlighted a potential alteration of brain tissue as well as an accelerated aging during long space travels due to the effect of heavy energy ions, which do not affect not the earthlings because of the protective global magnetosphere.
"Heavy ions such as iron and silicon cause damage because of their higher mass than massless photons such as X-rays and gamma (γ) scattered over the Earth, as well as low mass protons in the space, "says the study. Senior Researcher, Kamal Datta, MD, Associate Professor in the Department of Biochemistry and Project Leader of NASA's Specialized Research Center (NSCOR) at GUMC.
"With current protection technology, it's hard to protect astronauts from the damaging effects of heavy ionic radiation." While there may be a way to use drugs to counter these effects, no such agent It has not been developed yet, "said Datta, also a member of the Georgetown Lombardi Comprehensive Cancer Center. "Although short trips, such as those that astronauts have traveled on the moon, do not expose them to this level of damage, the real concern is the lasting injury of a long drive like that of Mars or the other. other missions in the deep space that would be much longer "says.
The gastrointestinal tract is a self-renewing tissue with continuous cell division / proliferation, according to the researchers. The (upper) mucosal layer of cells is replaced every three to five days by the coordinated migration of new cells from the bottom of a vial-like structure called crypt to the lumen of the intestine. "Any disruption of this replacement mechanism causes dysfunctional physiological processes such as nutrient uptake and triggers pathological processes such as cancer," said Albert Fornace Jr., co-author of Georgetown, director of NSCOR .
To study the effect of heavy ions on the gastrointestinal tract, scientists have used the small intestine of the mouse as a model system. Mice were exposed to a low dose of ferrous radiation at NASA's Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory on Long Island, New York, and the animals were examined in Georgetown.
The researchers compared the group of mice that received heavy ions with gamma-exposed mice, comparable to X-rays, and a third unexposed control group. Scientists discovered that intestinal cells in the heavy ion group did not absorb nutrients properly and formed cancerous polyps.
In addition, there was evidence that radiation-induced DNA damage increased the number of senescent cells. Senescent cells are incapable of normal cell division, but they are not "silent," says Datta.
"They generate oxidative stress and inflammatory molecules that cause more damage.This greatly affected the migration of cells needed to replace the intestinal mucosa, which slowed the functioning of the GI," he said. declared.
Even though a very low dose has been administered for months in deep space, the effects of heavy ionizing radiation seem to be permanent, says Fornace.
"We have documented the effects of deep space radiation on some vital organs, but we believe that similar damage reactions can occur in many organs," says Datta. "It is important to understand these effects in advance so that we can do everything we can to protect our future space travelers."
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Material provided by Georgetown University Medical Center. Note: Content can be changed for style and length.
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