Located about 5.8 billion light years from Earth in the Phoenix
Constellation, astronomers have confirmed the first example of a galaxy cluster
where large numbers of stars are being born at its core.
Galaxy clusters are the largest structures in the cosmos that are held
together by gravity, consisting of hundreds or thousands of galaxies embedded in
hot gas, as well as invisible dark matter.
The largest supermassive black holes known are in galaxies at the centers of
these clusters.
For decades, astronomers have looked for galaxy clusters containing rich
nurseries of stars in their central galaxies. Instead, they found powerful,
giant black holes pumping out energy through jets of high-energy particles and
keeping the gas too warm to form many stars.
Now, scientists have compelling evidence for a galaxy cluster where stars
are forming at a furious rate, apparently linked to a less effective black hole
in its center. In this unique cluster, the jets from the central black hole
instead appear to be aiding in the formation of stars. Researchers used new
data from NASA’s Chandra X-ray Observatory and Hubble Space Telescope, and the
NSF’s Karl Jansky Very Large Array (VLA) to build on previous observations of
this cluster.
Image Credit: X-ray: NASA/CXC/SAO/G.Schellenberger et al.; Optical:SDSS
https://www.nasa.gov/image-feature/stars-are-being-born-in-the-depths-of-a-black-hole
Researchers using MRI have found signs of damage that may be related to
inflammation in the brains of obese adolescents, according to a study being
presented next week at the annual meeting of the Radiological Society of North
America (RSNA).
Obesity in young people has become a significant public health problem. In
the U.S., the percentage of children and adolescents affected by obesity has
more than tripled since the 1970s, according to the Centers for Disease Control
and Prevention. Data from the World Health Organization indicates that the
number of overweight or obese infants and young children ages five years or
younger increased from 32 million globally in 1990 to 41 million in 2016.
While obesity is primarily associated with weight gain, recent evidence
suggests that the disease triggers inflammation in the nervous system that
could damage important regions of the brain. Developments in MRI like diffusion
tensor imaging (DTI), a technique that tracks the diffusion of water along the
brain’s signal-carrying white matter tracts, have enabled researchers to study
this damage directly.
For the new study, researchers compared DTI results in 59 obese adolescents
and 61 healthy adolescents, ages 12 to 16 years. From DTI, the researchers
derived a measure called fractional anisotropy (FA), which correlates with the
condition of the brain’s white matter. A reduction in FA is indicative of
increasing damage in the white matter.
The results showed a reduction of FA values in the obese adolescents in regions
located in the corpus callosum, a bundle of nerve fibers that connects the left
and right hemispheres of the brain. Decrease of FA was also found in the middle
orbitofrontal gyrus, a brain region related to emotional control and the reward
circuit. None of the brain regions in obese patients had increased FA.
“Brain changes found in obese adolescents related to important regions
responsible for control of appetite, emotions and cognitive functions,” said
study co-author Pamela Bertolazzi, a biomedical scientist and Ph.D. student
from the University of São Paulo in Brazil.
This pattern of damage correlated with some inflammatory markers like
leptin, a hormone made by fat cells that helps regulate energy levels and fat
stores. In some obese people, the brain does not respond to leptin, causing
them to keep eating despite adequate or excessive fat stores. This condition,
known as leptin resistance, makes the fat cells produce even more leptin.
Worsening condition of the white matter was also associated with levels of
insulin, a hormone produced in the pancreas that helps regulate blood sugar
levels. Obese people often suffer from insulin resistance, a state in which the
body is resistant to the effects of the hormone.
“Our maps showed a positive correlation between brain changes and hormones
such as leptin and insulin,” Dr. Bertolazzi said. “Furthermore, we found a
positive association with inflammatory markers, which leads us to believe in a
process of neuroinflammation besides insulin and leptin resistance.”
Dr. Bertolazzi noted that additional studies are needed to determine if
this inflammation in young people with obesity is a consequence of the
structural changes in the brain.
“In the future, we would like to repeat brain MRI in these adolescents
after multi-professional treatment for weight loss to assess if the brain
changes are reversible or not,” she added.
Source: https://www.eurekalert.org/pub_releases/2019-11/rson-mrb111819.php
