Chemical difference in elderly stem cells
Elderly stem cells have chemical instructions written on the shells of their DNA
that are dramatically different from their younger counterparts, a finding that
may give scientists clues into cellular aging and the body's ability to repair
The discovery was made by Stanford researchers studying histones -- protein
shells that coat DNA. Etched into histones are chemical codes that tell cells
which genes should be turned off or on, and those variances are what make some
cells neurons, for example, as opposed to any other cell in the body.
The Stanford team, studying mice, looked at stem cells that were destined to
become muscle cells. In young mice, the code on the histone was more permissive
-- there were both "on" and "off" instructions -- than in older mice, in which
the code included far more "off" signals.
That suggests that as the stem cells age, they become more locked into a certain
fate -- in the case of this study, becoming a muscle cell. When stem cells are
younger, they may be more flexible.
Results of their study will have little immediate impact on human aging and
health, but it provides an intriguing clue to the importance of chemical coding
and how scientists may someday be able to rewrite those instructions. The
research was published in the June 27 issue of Cell Reports.
- Erin Allday
Changes that lead to precancerous condition
Disruption of a particular line of cellular communication may cause stem cells
in the esophagus to become stomach-like cells, a transformation that happens in
a form of pre-cancerous disease called Barrett's esophagus.
Scientists at the Buck Institute for Research on Aging are studying a type of
fruit fly known to share many cellular similarities to humans. In particular,
they are looking at a specific line of communication between cells that is found
in both humans and fruit flies, and that is known to be involved in Barrett's
esophagus. The signaling pathway is called BMP-like Dpp.
In the fruit flies, when scientists manipulated the signaling pathway, stem
cells in the insects' esophagus that ordinarily would turn into esophageal cells
instead became stomach stem cells.
Doctors have long suspected that Barrett's esophagus is caused by gastric reflux
-- a condition in which gastric acid from the stomach leaks up into the
esophagus -- but the Buck scientists believe their work shows that there may be
more complex processes going on.
The research was published online June 27 in the journal Cell Reports.
- Erin Allday
Skin cancer deadlier in young men
Young men are more likely to die from melanoma, the deadliest form of skin
cancer, than women of the same age, according to a study by Stanford
The findings showed that men had a 55 percent higher risk of death from the
disease, suggesting that biological differences in gender may play a bigger role
in survival than previously thought.
Researchers looked at more than 26,000 cases of white people ages 15 to 39 years
old who were diagnosed with melanoma between 1989 and 2009. Although males made
up 40 percent of the cancer cases, they accounted for 64 percent of the deaths.
The overall findings of a 55 percent increased risk of death took into account
other factors such as the thickness of the tumor, its location, subtype and
whether it had spread to other parts of the body.
The study was published online June 26 in the journal JAMA Dermatology.
- Victoria Colliver
Damage from blasts may be treatable after all
Hearing loss from loud blasts such as roadside bombs may be more treatable than
previously thought, a study by Stanford researchers has found.
In research using mice, the scientists discovered that loud blasts actually
cause hair-cell and nerve-cell damage in the inner ear, rather than structural
damage to the cochlea, the delicate spiral-shaped auditory cavity that contains
the nerve endings essential for hearing.
Researchers said this opens more possibilities to try to repair the damage, news
that should be encouraging for the millions of soldiers and civilians who suffer
long-term hearing loss as a result of these blasts.
More than 60 percent of service members who have been wounded in action have
eardrum injuries, tinnitus, hearing loss or a combination of these issues,
according to the study.
The study was published online Monday in the journal PLOS ONE.
- Victoria Colliver
Deprivation may lead to increased anxiety
Losing sleep doesn't just make you, well, tired. New research from UC Berkeley
shows it may also increase your anxiety level.
Neuroscientists found that sleep deprivation ramps up the regions of the brain
that contribute to excessive worrying -- the amygdala and insular cortex. The
resulting neural activity is similar to that seen in anxiety disorders.
Those who are naturally more anxious and prone to having an anxiety disorder are
more vulnerable to insufficient sleep, and may benefit from sleep therapy, the
The study involved brain scans of 18 healthy young adults after a good night's
rest and again after a sleepless night. In each case, the adults viewed images
that were neutral, like a basket on a table, or disturbing, like a death scene.
When the subjects were sleep-deprived, researchers noted that activity was high
in their emotional brain centers as they waited for a neutral or disturbing
image to appear on a screen.
The research appeared last week in the Journal of Neuroscience.
- Stephanie M. Lee
Older spouses tend to evade quarrels
Are you and your spouse arguing over how to spend the Fourth of July? You're
probably young, because the older you get, the more likely you are to avoid
addressing the issue -- that is, by changing the subject.
That's the gist of a new psychology study from San Francisco State University.
Researchers followed 127 middle-aged and older married couples for 13 years,
periodically videotaping their discussions to study their communication styles
when they argued.
As time went on, both husbands and wives became increasingly likely to change
the subject when an argument arose.
This may sound unhealthy, but researchers say that older couples who have had
years to disagree may actually benefit from focusing on more neutral or pleasant
subjects, and staying away from topics they know are "toxic."
The study appeared Wednesday in the Journal of Marriage and Family.
- Stephanie M. Lee
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