GREENHOUSE GASES
Satellite reveals carbon cycle details
Participants tested identical creams either from a cheaper-looking orange box or a blue box designed to appear more expensive.
C R E D I T: N ASA /JE T P RO P U LS I O N LA BO RATO RY/CA LT EC H ( SATE LL I T E) ; CO U RT ESY O F A L EXAN DRA T I N N E R M A N N (CR EAM S )
NEUROSCIENCE NASA’s Orbiting Carbon Observatory 2 (OCO-2) satellite, launched in 2014, measures atmospheric carbon dioxide levels with a spatial resolution of 3 km2. Data from the satellite will help scientists understand the global carbon cycle—and how that cycle may change in response to global warming. A set of five papers in Science analyzes OCO-2 data collected from 2014 to 2016, identifying seasonal effects on the carbon cycle as well as the influence of the 2015– 16 El Niño weather event. In one study, a team led by Junjie Liu of NASA’s Jet Propulsion Laboratory determined that tropical regions all released more carbon to the atmosphere during the El Niño event than average and that the releases had different origins—biomass burning in Asia, lower precipitation in South America, and higher temperatures in Africa (Science 2017, DOI: 10.1126/science.aam5690). These results, combined with expected precipitation and temperature changes in response to global warming, suggest that tropical lands may be a source rather than a sink of carbon in the future. Another study looked at whether scientists may quantify plant biomass production by measuring solar-induced chlorophyll fluorescence via satellite, as suggested by previous research. Researchers led by Ying Sun of Cornell University and Christian Frankenberg of Caltech validated the space-based approach by comparing OCO-2 fluorescence measurements with ground and airborne data (Science 2017, DOI: 10.1126/science. aam5747).—JYLLIAN KEMSLEY
Pricier drug causes more pain in study participants New fMRI technique connects nocebo effects to neural activity The placebo effect, in which people’s expectations lead them to experience the benefits of a treatment despite not receiving an active drug, has an evil twin: the nocebo effect. Scientists don’t know as much about this less pleasant effect, in which people’s negative expectations cause them to experience adverse side effects, mostly because of the ethical challenges of inducing bad outcomes on purpose. Yet both effects have the power to disrupt a treatment’s outcome or skew the results of clinical drug trials. In these psychological phenomena, many factors can influence a patient’s expectations, including a drug’s price tag. Through tests of people’s behavior and neurological activity, researchers at the University Medical Center Hamburg-Eppendorf now show that more expensive drugs have stronger nocebo effects (Science 2017, DOI: 10.1126/ science.aan1221). In the study, healthy participants were told they were involved in a test of two versions of a topical cream to treat eczema and that the cream may increase sensitivity to pain. One group would test the “cheap” version packaged in an orange box and the other group would test the “expensive” blue box version. None of the creams contained any active ingredient. The participants applied both what they were told was a control cream and their designated test cream on their arms and put on arm patches attached to a heating machine. During the experiment, the patches were heated to cause a medium amount of pain. Participants in both the
“expensive” and “cheap” cream groups experienced the nocebo effect, meaning they felt more pain with the test cream than with the control cream even though the creams had the same ingredients. This effect was more pronounced in the “expensive” group: The pain differential between test and control creams for those participants was 30%, whereas the “cheap” group rated the test cream only 3% more painful. The researchers propose that participants assume pricier drugs contain ingredients that are more effective and potent and thus cause more side effects. During the pain exposures, the researchers also monitored participants’ neural activity with functional magnetic resonance imaging (fMRI) using a new method that allows them to look at activation in both the brain and spinal cord. Usually scientists can monitor either the brain or the spinal cord because it’s difficult to find parameters that allow them to see both, says lead author and graduate student Alexandra Tinnermann. The team was able to correlate the stronger nocebo effect in the “expensive” group with neural interactions in areas of the prefrontal cortex, brain stem, and spinal cord. The findings suggest that “for the same painful stimulation, we can have different signaling at the level of the spinal cord and brain region because of our expectations based on a drug’s price,” says Luana Colloca, an anesthesiology professor at the University of Maryland School of Nursing.—TIEN NGUYEN OCTOBER 16, 2017 | CEN.ACS.ORG | C&EN
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