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Now, scientists have collected the largest space biology dataset to date based about astronauts, including the Kelly twins, mice and insects that flew to the space station.
The 30 studies, written by more than 200 researchers from around the world, represent the largest body of information on the risks of space flight to the human body.
Studies identify six key molecular changes that can have a significant impact on astronauts’ health. Understanding these changes is key to preparing for long-term space missions to the Moon and Mars in the future.
Risks of deep space missions
The six molecular changes that occur during space flight include DNA damage, oxidative stress, alterations in telomere length, changes in the microbiome, mitochondrial dysfunction, and gene regulation.
Oxidative stress occurs when free radicals overwhelm the antioxidants in a cell, encouraged by the space environment. It has been found that this type of stress is largely related to the other molecular changes observed by the researchers.
These changes at the cellular and molecular level can have a significant impact on the health of astronauts, both during and after their missions. These impacts have been observed on the cardiovascular, central nervous, musculoskeletal, immune and gastrointestinal systems, as well as causing disruption of circadian rhythms and changes in vision.
Increased cancer risk has also been associated with these changes.
One of the new studies also identified clonal hematopoiesis, when mutated blood cells spread more rapidly than others, as a potential risk among astronauts for cardiovascular disease, lymphoma and leukemia. Clonal hematopoiesis was identified in astronaut blood samples 20 years earlier than mean age when it is normally detected at age 70, compared with 157 cancer patients.
So far, the space station missions haven’t passed a year, but deep space missions to Mars could last up to five years.
“Understanding the health implications of the (6) features and developing effective countermeasures and health systems are key steps to enable humanity to reach the next stage of space exploration,” wrote the authors at the conclusion of their study on the effects of space flight.
DNA damage
Telomeres act as caps on the ends of chromosomes to protect them and shorten as we age.
During the twin study, the telomeres in Scott’s white blood cells actually elongated in space and returned to a normal length after his return to Earth.
In a new study, blood samples from 10 astronauts collected before and after the space flight were studied and compared with the results of the Twins Study.
Although these astronauts were protected from some space radiation during their six-month stays on the space station as it is in low Earth orbit, the researchers nevertheless found evidence of damage to their DNA.
Astronauts’ telomeres have stretched out into space due to chronic oxidative stress sustained during space flight. Once they returned to Earth, their telomeres were shorter than before space flight.
“We now have a foundation to build on – things we know how to look for in future astronauts, including changes in telomere length and responses to DNA damage,” Susan Bailey, author of three studies and a Colorado State professor, said in a statement. University. .
“Moving forward, our goal is to get a better idea of the underlying mechanisms, what is happening during long-duration spaceflight in the human body and how it varies between people.”
Bailey, an expert on radiation damage to DNA and telomeres, was also an investigator for the Twins Study.
While longer telomeres may seem like a benefit of space travel, Bailey suspects this effect could lead to other risks rather than serving as a fountain of youth.
“The extended lifespan, or immortality, of cells that have undergone DNA damage induced by space radiation, such as chromosome reversals, is a recipe for increased cancer risk,” Bailey said. “Telomeres really reflect our lifestyles, both on and off the planet. Our choices make a difference in how fast or how well we are aging. It is important to take care of your telomeres.”
It’s all in the mitochondria
Health problems specific to astronauts include loss of muscle and bone, heart and liver problems, and immune system dysfunction.
Now, the researchers believe these problems are rooted in a larger problem called mitochondrial dysfunction.
Mitochondria are the power plants that generate the chemical energy required for cells. And when they’re exposed to altered gravity or radiation, they essentially malfunction.
“What we’ve found over and over is that something is happening with the regulation of mitochondria that knocks everything out.”
Their study included data from the Twins Study, animal studies, and samples from 59 astronauts.
When mitochondria are suppressed, knock-on effects can be observed on the liver, other organs and the immune system. Researchers believe this dysfunction could also explain the problems astronauts have with disrupted circadian rhythms (biological clocks) and even cardiovascular problems.
Understanding the root of the problem could help researchers pinpoint it.
“There are already many drugs approved for various mitochondrial disorders, which would make it easier to move them to this application,” Beheshti said. “The lowest fruit now would be to test some of these drugs with animal and cell models in space.”
Heart stress in space
A study using fruit flies born on the space station, meaning they spent half their lives in space, showed that their hearts were smaller and less efficient at pumping blood. And if astronauts live on the moon or on the surface of Mars for a long mission, they may experience something similar.
“For the first time, we can see the cellular and molecular changes that may underlie the heart conditions seen in astronaut studies,” said Karen Ocorr, senior co-author of the study and assistant professor in the Development, Aging and Regeneration Program. to Sanford Burnham Prebys Medical Discovery Institute, in a statement.
“We started this study to understand the effects of microgravity on the heart, and now we have a roadmap that we can use to start developing strategies to keep astronaut hearts strong and healthy.”
Fruit fly hearts are similar to those of humans when we are in the womb. The flies were brought back to Earth and their heart function tested by seeing how they behaved when climbing over the side of a test tube.
“In normal fly heart, muscle fibers work like fingers when squeezing a tube of toothpaste. In space flies, the contraction was like trying to extract toothpaste by pressing down instead of squeezing,” Ocorr said. “For humans, this could become a big problem.”
The benefits of understanding how the human heart works in space could help those with heart problems on Earth and those planning future space missions.
“As we continue our work to establish a colony on the moon and send the first astronauts to Mars, it is imperative to understand the effects of prolonged time in microgravity on the human body,” said Sharmila Bhattacharya, author of the study and senior scientist at NASA. in a statement.
“Today’s results show that microgravity can have dramatic effects on the heart, suggesting that medical intervention may be needed for long-lasting space travel and indicate different directions for therapeutic development.”
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