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Science Policy Around the Web – April 16, 2019

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By: Mary Weston, PhD

Source: Wikimedia

Astronaut twins study spots subtle genetic changes caused by space travel

In 2015, NASA began their Twins Study, where they evaluated the biological effects of one year of spaceflight on an astronaut by comparing him to his earthbound identical twin. One year after returning to earth, the majority of observed physiological changes from space reverted back to the astronaut’s original state, with only subtle genetic changes remaining. 

Spaceflight exposes the body to ionizing radiation and near-zero gravity, and the consequences of long-term exposure to these conditions are not known. On this mission, Scott Kelly spent 340 days in space from 2015-2016 (he has a lifetime total of 520 space days). His brother Mark, a retired astronaut who had previously spent 54 days in space over four space-shuttle missions, remained on earth and acted as a near identical biological control. The study involved only two people, so not all findings may be applicable to other astronauts, but NASA hopes to use the information to direct future astronaut health studies.

Teams of researchers gathered a wide array of genomic, molecular, physiological, and other data on the men before, during, and after the mission. They reported that Scott Kelly did display signs of stress from space travel, with changes seen in most areas measured. 

However, now researchers are finding that most of the changes Scott Kelly experienced from spaceflight have reverted back to their original state after 6 months of being back on earth. NASA argues that “the Twins Study demonstrated the resilience and robustness of how a human body can adapt to a multitude of changes induced by the spaceflight environment”.

One genetic change that did persist six months after Scott’s return was to his chromosomes. Parts of them inverted (flipped), which could lead to DNA damage, and is possibly due to the large amounts of space radiation. Further, researchers hypothesized that space flight would shorten telomers, important caps at the end of chromosomes, since they decrease with age and spaceflight is expected to stress the body similar to aging. However, a majority of his telomers lengthened while Scott Kelly was in space, while only few shortened. Those that lengthened returned to their normal state after about 48hrs on earth, but the shortened ones remained. 

Given the space community’s interest in increasingly ambitious space missions and plans to explore Mars, studies exploring the long-term health impacts of spaceflight will be extremely important for the future.

(Alexandra Witze, Nature


Abnormal Levels of a Protein Linked to C.T.E. Found in N.F.L. Players’ Brains, Study Shows

Last week, the New England Journal of Medicine published a study that used experimental brain scans to compare the levels and distribution of tau, a protein linked to chronic traumatic encephalopathy (CTE), in retired NFL players and male controls who had never played football. They found that the NFL players had elevated levels of tau in areas where the protein had previously been detected postmortem. 

CTE is associated with repetitive hits to the head, like those encountered during contact/collision sports. Currently, pathologists can only posthumously diagnose CTE. This new study is the first to evaluate tau averages and overall patterns from a group of living former football players (26 men) with a control group (31 men). The project, led by Dr. Robert Stern of Boston University, used Positron Emission Tomography (PET) scans to image the brain after exposure to a radiolabeled substrate that specifically binds tau. 

Both the study’s authors and outside experts emphasize that a CTE diagnostic test is still far from ready and would likely include other markers from blood and spinal fluid as well.  However, this study represents a preliminary, first step towards developing a clinical test to detect CTE in living players, which may also ultimately assist in identifying early disease signs and those with potential risk of developing CTE. 

The relationship between CTE symptoms and the role of tau, which occurs naturally in the brain, is not clear. The study found no correlation between the amount of abnormal tau and the severity of cognitive and mood problems in the players. However, these results are preliminary and the player sample size was small. Evaluation of larger sample size of football players is needed to continue to explore the role of tau and replicate the observed elevated levels found in this paper. 

(Ken Belson and Benedict Carey, New York Times


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Written by sciencepolicyforall

April 17, 2019 at 9:34 am

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