Space doesn’t make good blood

In terms of technology, long-term space travel seems closer than ever. Space X continues flight tests of Starship Project, a fully reusable transportation system designed for long-duration interplanetary flights (with Mars in the viewfinder), NASA is confident of realizing Artemis project To return to the moon and the CNSA (Chinese Space Agency) is studying one new copy From the Long March 5 vector capable of dropping one of its astronauts onto our satellite within a few years (with a dream of Mars in the stairs). Giant strides compared to the technological panorama of the years when the USA and the Soviet Union competed for the priority of space and the conquest of the Moon. However, human missions in space, especially those of longer duration, cannot leave aside the numerous and troubling weaknesses that a human being exhibits when he leaves the comforting planet of his host for extended periods. In recent months, two more disturbing discoveries have been added to the two now known.

The brain is in danger?

first discovery published Online last October on Gamma Neurology by Peter zu Eulenburg (Ludwig-Maximilians-University Munich) and collaborators, relates to the presence in the blood of some astronauts of high levels of proteins that are typically found in patients with head injuries or neurodegenerative diseases. Although the sample the study authors examined is very small – only five astronauts – the picture that emerges cannot be underestimated. Discovering that astronauts have returned to Earth after making long missions Visual impairment It prompted researchers to investigate more deeply the importance of a prolonged stay in space for the human brain.

A few years ago, on New England Journal of Medicine, Donna Roberts (Medical University of South Carolina) and collaborators have published a relationship About two dozen astronauts described how, using magnetic resonance of the brain, a loss of gray matter volume and an increase in the volume of cerebrospinal fluid were detected. However, research has not assessed what these brain changes may entail for health and cognitive processes. Just to try to clarify this important aspect and to research the impact of possible brain injuries, zu Eulenburg’s group measured the levels of five different proteins in the blood of five male astronauts before and after a stay of about six months on the space station. It is true that the best fluid for studying these biomarkers is cerebrospinal fluid, but access to it requires an aggressive spinal tap. For this reason, the researchers opted for blood analysis, just as reliable but with significantly fewer problems obtaining samples.

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After measuring protein levels 20 days before launch, the researchers calculated the average level of each protein in the five astronauts. Once the space mission ended, three more samples were taken (one day, one week and twenty days after the return) and levels were compared to the average.

The analysis showed that the level of the two proteins remained at high levels even after a week of return, and although it decreased in the following two weeks, it remained above the average level for each astronaut. For two other proteins, it was observed that their relationship followed a trend sometimes found in patients undergoing neurodegenerative conditions. “Obviously this is an experimental study – as Zoe Yullenberg said – but the quality of the data and the analysis are so solid that I have no doubts about the overall effect. Very surprisingly, some levels remained high over the three weeks: the results show evidence of brain damage from long-term exposure. for microgravity conditions.

Commenting on the findings, Donna Roberts (not involved in the research) said: pointed out The study contains data that suggests there may be some type of brain injury, but she believes that more detailed analysis is needed not only to measure vital signs for a longer period after the astronauts return, but also during their stay on the space station. This can help determine if the elevated levels are actually due to time spent in microgravity or if the cause is, alternatively, a sudden change in gravity upon return to Earth or in the intense force that occurred during the descent.

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Anemia in space

The second studioPublished by Guy Trudel (Ottawa Hospital Research Institute) and its collaborators nature medicine In the middle of January, it comes to the so-called space anemia, that is, the sharp decrease in the number of red blood cells that occurs in astronauts. Prior to this study, space anemia – which is consistently reported from early missions – was thought to have been a rapid adaptation to the movement of fluids in the upper body of an astronaut upon arrival in space. This phenomenon entails a loss of 10% of the fluid in the astronauts’ blood vessels and it was believed that the rapid destruction of 10% of red blood cells was the way to restore the necessary balance, but everything would return to normal after about ten days. in the space.

Instead, Dr. Trudel’s team found that the destruction of red blood cells is not the result of moving fluids, but a primary effect of their presence in space. They came to this startling conclusion by directly measuring the loss of red blood cells in 14 astronauts during their six-month mission to the space station. The data collected indicates that while staying on the station, astronauts destroyed 54% more red blood cells than they normally would on Earth. The results, which do not discriminate between sex, remain practically identical for both female and male astronauts.

This study shows that at the time of their return to Earth, 5 out of 13 astronauts—not one taken—were clinically anemic. Fortunately, space-related anemia appears to be reversible: red blood cell levels, in fact, gradually return to acceptable values ​​three or four months after they return to Earth. Very gradual return to normal, given that by repeating the measurement one year after return, red blood cell destruction was still 30% higher than levels detected before the task.

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Even more worrying, especially when considering long-duration missions like the mission to Mars, is that the level of anemia is directly related to the duration of a space mission. Indeed, this is the conclusion reached by Trudel and his collaborators in one studio Posted in December 2019 onAmerican Journal of Hematology Which took into account more than 17,000 hemoglobin concentration measurements, collected more than 721 space missions. Case indicates some considerations. In addition to highlighting the need to define and prepare a targeted diet for astronauts, it also points out the importance of taking into account individual levels of red blood cells not only in choosing future astronauts, but also in choosing a “simple space tourist.” Finally, this will be clarified in The earliest possible time to how long the organism can withstand this abnormal rate of destruction and production of red blood cells without serious consequences.

In short, the dream of man on Mars is not really within reach.

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