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Chemical difference in elderly stem cells


1SF

07-03-13

July 03--AGING

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 itself.

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

BARRETT'S ESOPHAGUS

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

MELANOMA

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 researchers.

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

HEARING

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

SLEEP

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 researchers said.

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

MARRIAGE

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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