June 19--SMALL MOLECULES
New chemical found, aids mouse memory
Mice injected with a newly identified chemical improved their performance on
several simple memory tests, a finding that could help scientists better
understand a host of human memory disorders associated with brain diseases and
aging, according to researchers at UCSF.
Scientists found the molecule after screening 100,000 chemicals at UCSF's Small
Molecule Discovery Center. The molecule, called integrated stress response
inhibitor (ISRIB), is able to counteract the effects of a protein that may halt
memory formation when cells are under stress.
When the protein is activated, it beefs up production of other proteins that
help cells cope with stressors like DNA damage or viral infections. But at the
same time, activation of that protein shuts down other proteins that are thought
to be involved with building memories.
The ISRIB chemical appears to interfere with the process of shutting down
Mice given the chemical were three times faster at locating a submerged platform
than mice that received a placebo. They also were better at recalling cues
associated with negative stimuli.
The chemical is not ready to be tested in humans. Instead, scientists hope to
use it to improve their understanding of diseases that affect the memory, as
well as biological reactions to stress.
Results of their research were published May 28 in the journal eLife.
- Erin Allday
Protein linked to circadian clock
Scientists at the Gladstone Institutes have found evidence that a protein known
to play an important role in several metabolic processes seems to ebb and flow
in time with the body's circadian clock.
When the scientists disrupted the clock of mice by removing a gene known to help
control the circadian rhythm, they found that production of the protein, called
p75 neurotrophin receptor, waned. The drop in protein production seemed to
disrupt circadian genes in the brain and liver, plus genes that help regulate
glucose and fat metabolism.
All of those effects suggest that the protein is not only closely tied to the
body's circadian clock, but that removing the protein further disrupts the clock
and important metabolic processes.
Scientists believe the discovery could improve research into the complex
biological processes that make up the circadian clock. And it adds more proof to
the idea that the circadian clock plays an important role in maintaining a
A paper on their research was published Tuesday in the Journal of Neuroscience.
- Erin Allday
Brain doesn't sweat small stuff
When the human brain is faced with making sense of complex sounds, it focuses on
the big picture instead of the little details, new UC Berkeley research shows.
In the study, nearly two dozen participants overall could judge the average
pitch of a brief sequence of tones. But they had trouble recalling information
about individual tones within the sequence.
The authors said their results suggest that the brain automatically summarizes
sounds, such as music, to get a gist of what is being heard, instead of
processing individual notes. The findings could be used to, for example, improve
hearing aids so that hearing-impaired people can tune into one conversation
while multiple conversations are going on in the background.
The study was published last week in the journal Psychological Science.
- Stephanie M. Lee
Brain wiring and communication gaps
Autistic children often struggle to grasp the social and emotional aspects of
human speech, and a new study from the Stanford University School of Medicine
illuminates a brain mechanism that could explain why.
In autistic youth, brain regions tailored to respond to voices are poorly
connected to reward-processing circuits that normally allow children to
experience speech as pleasurable, the authors said.
The study involved 20 children with a high-functioning form of autism: they
could speak and read but had difficulty understanding emotional cues in another
person's voice. The scientists compared MRI brain scans from these children with
scans from 19 typically developing children.
They found that in the autistic group, the voice-selective cortex on the left
side of the brain was weakly connected to brain structures that release dopamine
in response to rewards: the nucleus accumbens and the ventral tegmental area.
And the voice-selective cortex on the right side of the brain, which specializes
in detecting vocal cues such as intonation and pitch, was weakly connected to
the amygdala, which processes emotional cues.
The weaker these connections in autistic children, the worse their communication
gaps, the study found. Scientists say their findings could help develop new
treatments for autism.
The study appeared Monday online in Proceedings of the National Academy of
- Stephanie M. Lee
Fewer, weaker scans may cut kids' cancer risk
Reducing the number of unnecessary CT scans for children and lowering the doses
for the highest-dose scans could cut the lifetime risk of imaging-related
cancers by as much as 62 percent, UC Davis researchers have found.
Radiation doses delivered by CT, or computed tomography, are 100 to 500 times
greater than conventional X-rays and are associated with increased cancer risk.
The researchers estimated 4,870 future cancers could be caused by the
approximately 4 million CT scans performed on children each year. They found
that just by reducing the amount of radiation in the highest 25 percent of the
CT scans in children, about 43 percent of future cancers could be prevented.
CT use increased from 1996 to 2005, doubling for children younger than 5 and
tripling for children between ages 5 and 14 during that time period. That
percentage started decreasing after 2007, possibly because of concerns about
Researchers conducted the study by examining nearly 750 CT scans of the head,
abdomen/pelvis, chest and spine conducted on children under the age of 15
between 2001 and 2011.
The study was published online June 10 in JAMA Pediatrics.
- Victoria Colliver
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