Research news in brief

Low fitness associated with larger waist size, more inflammation

Danish researchers have found that low fitness is associated with a larger waist size and a higher degree of inflammation. The researchers analysed the previously collected data of 10 976 individuals from the Danish Health Examination Survey 2007–2008. These individuals took a maximal oxygen uptake (VO2max) test to assess their physical fitness. Their waist circumference, weight and height were measured, and blood samples were taken to measure their level of C-reactive protein, a non-specific biomarker of low-grade inflammation. They found that higher levels of fitness were associated with a smaller waist circumference and a lower degree of inflammation independently of body mass index (BMI). The researchers acknowledged that there were possible limitations that may affect the findings of the study, but overall, the results suggested that increased fitness has the potential to reduce abdominal fat mass and inflammation, which may improve metabolic health irrespective of BMI. “We found that fitness is inversely associated with both abdominal adiposity and low-grade inflammation independent of BMI,” the lead author said. The research was published in PLOS ONE.

Pupils fluctuate during sleep: mouse study

Swiss scientists have found that the pupils in the eyes of mice fluctuate in size during sleep depending on what stage of sleep they are in. The team used an infrared light and camera to see inside the heads of the mice and noted that the smaller the pupil, the further through their sleep states the mice were. The researchers suggest the new method could replace or compliment current sleep study tools in humans. The researchers developed a novel optical pupil-tracking system. The device includes an infrared light positioned close to the head of the animal. That invisible light travels through the skull and brain to illuminate the back of the eye. When the eyes are imaged with an infrared camera, the pupils appear as bright circles. Thanks to this new method, it was suddenly possible to track changes in pupil size accurately, particularly when the animals snoozed naturally with their eyelids open. Their images show that mouse pupils rhythmically fluctuate during sleep and that those fluctuations are not random; they correlate with changes in sleep states. Further experiments showed that changes in pupil size are not just a passive phenomenon either. They are actively controlled by the parasympathetic autonomic nervous system. The evidence suggests that in mice, at least, pupils narrow in deep sleep to protect the animals from waking up with a sudden flash of light. “The pupil continues to play an important role during sleep by blocking sensory input and thereby protecting the brain in periods of deep sleep, when memories should be consolidated,” the authors said, adding that they would like to find out whether the findings hold in humans and whether their new method can be adapted in the sleep clinic. “Inferring brain activity by non-invasive pupil tracking might be an interesting alternative or complement to electrode recordings,” they said. The research was published in Current Biology.

New blood test for early cancer detection

A US-led research team working with collaborators from the Walter and Eliza Hall Institute of Medical Research (WEHI) has developed a new blood test or “liquid biopsy” for the early detection of eight common cancers, diagnosing tumours before they have spread, while the chance of cure is still high. Called CancerSEEK and developed by researchers at Johns Hopkins University, the blood test screens for key proteins and gene mutations that indicate the presence of one of eight types of cancer: ovary, liver, stomach, pancreas, oesophagus, bowel, lung and breast. While screening tests for some cancers have already been developed and are associated with earlier diagnosis and better outcomes, for many major tumour types there are no effective screening tests. The currently available screening tests can also be unpleasant, have associated risks and uptake can be low. Significantly, each test can only screen for one cancer at a time. CancerSEEK tests were positive in a median of 70% of the eight cancer types. The test was able to positively detect between 69% and 98% of people who had one of five cancer types (ovary, liver, stomach, pancreas and oesophagus) for which there are no screening tests currently available (for average-risk individuals). The specificity of CancerSEEK was greater than 99%, meaning that fewer than 1% of people had a false positive result from the test. Associate Professor Jeanne Tie, from WEHI, said: “CancerSEEK has the potential to be a one-stop, safe screening test for multiple tumour types that should have high community acceptance. For the first time we have the promise of a screening test that will lead to earlier diagnosis and improved survival outcomes for many tumour types that are major contributors to cancer deaths in our community”. The research is due to be published in Science.

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