One Carbon Metabolism on the Space Station   
       
   May 31, 2016:  It has been known for some time that time in space affects   
   astronauts' vision. Post-flight vision changes have been reported by many   
   astronauts after they spend time on the International Space Station. Many, but   
   not all. But why are only certain people affected by spaceflight in this   
   manner?'   
       
   Results of a new study involving 49 space station astronauts may help crack   
   this case. The research points to differences in the way some individuals'   
   bodies operate at the cellular level which may influence whether they develop   
   vision or eye issues in space.   
       
   https://www.youtube.com/watch?v=kmvFGc5Tt38   
       
   The human body is complex. Intricate networks of chemical interactions within   
   our cells convert basic nutrients from the foods we eat, into the molecules   
   that keep us ticking. These chemical processes use specific pathways, called   
   metabolic pathways, and are spurred by enzymes, each with its own job to do.   
       
   Scott M. Smith from the Biomedical Research and Environmental Sciences   
   Division at NASA's Johnson Space Center explains, "One of these pathways,   
   called the one carbon metabolism pathway -- moves single carbon atoms from one   
   compound to another in our cells. This is a nutrition and vitamin rich pathway   
   that involves folate, vitamins B6, B12, and other vitamins, and is extremely   
   important."   
       
   In the one carbon pathway, enzymes help by pulling a single carbon atom from a   
   folate or other carbon donor and attaching it to an amino acid, thus   
   converting it to a different amino acid. If anything goes wrong - for example   
   if this chain reaction doesn't work properly, slows down, or backs up, the   
   effect is felt down the line. Higher blood concentration of homocysteine in   
   affected astronauts was the first clue that this team found. This led to the   
   study of genetic differences in one carbon enzymes.   
       
   Smith says, "We found two genetic variances in the enzymes that facilitate the   
   one carbon pathway.  This may help explain why some astronauts' vision is   
   affected but not others." This represents the first time researchers have   
   identified a genetic marker associated with a spaceflight medical issue. In   
   fact this is also the first time that NASA has used human genetic data   
   directly in an investigation.   
       
   Smith continues, "We found that in addition to genetics, this effect was also   
   associated with B vitamin status. A missing piece of the puzzle, however, is   
   while we have shown an association between genetics and vision; we still don't   
   know the mechanism - or cause - of these effects. That's one of the keys to   
   figuring out how to prevent or treat this in affected crewmembers."   
       
   This could be important on Earth, too, because differences in these same   
   enzymes are associated with the occurrence of cardiovascular disease, stroke,   
   and other medical issues. We are also performing research to identify   
   similarities between characteristics of astronauts with vision issues and   
   women with endocrine system disorders, specifically, polycystic ovary   
   syndrome, or PCOS."  This beginning research is needed to document a possible   
   tie between astronauts with vision issues and women with PCOS.   
       
   These study results could ultimately help researchers identify who will   
   develop vision problems resulting from space flight, and importantly, help   
   identify genetic related medical associations in the general population.   
       
   Scientists looking at this problem from different perspectives have more   
   research to do before coming to a consensus. Smith notes, "This study merely   
   scratches the surface toward understanding the genetics and apparent   
   associated relationships."   
       
   For more from the international space station, go to www.nasa.gov/station   
       
   Stay tuned for updates about vision in space from science.nasa.gov   
       
       
   Regards,   
       
   Roger   
      
   --- DB 3.99 + Windows 10   
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