Imaging transplanted cells, health disparities in the U.S., and the Americas’ oldest writing.
Pat McCaffrey
MRI tracks islet cell transplants for diabetes
For the past five years, in a promising experimental treatment for type I diabetes, doctors have been injecting insulin-producing pancreatic cells, called islet cells, into patients’ livers in hopes that the cells will pump out insulin and cure the patients. Often, though, the islets don’t survive. Without a way to monitor the cells after they’ve been transplanted, doctors could only wonder what went wrong.
They could soon have a tool to help troubleshoot the procedure and improve their success rate. In a paper in this month’s Diabetes, Anna Moore of the Massachusetts General Hospital and colleagues from MGH and the Joslin Diabetes Center showed that they could detect the location and numbers of live transplanted islet cells in mice using noninvasive magnetic resonance imaging (MRI). They found clusters of these cells surviving in the mice’s livers. Unfortunately, half of the cells died in the two weeks after the transplantation.
By imaging both normal and immune-deficient mice regularly after transplantation, the authors found that immune rejection was an important contributor to islet cell death. But it was not the only cause—even in animals with no immune system, islets still died, although at a lower rate.
Previous work by the same researchers showed they could image transplanted islet cells in mice using MRI if the cells were first tagged with experimental, iron-containing nanoparticles.
In the current study, they used an imaging agent approved by the U.S. Food and Drug Administration that is already used to diagnose liver disease in humans. Being able to use this imaging agent paves the way for future tests of this MRI protocol in people.
Born in the USA, but which one?
Health disparities among races in the United States have been well documented: it’s known that blacks have a lower life expectancy than whites by several years. Now, a study from the Harvard School of Public Health that divided the American population more finely into eight groups reveals that the differences among some groups are even larger than previously recognized, and are showing no signs of shrinking.
The researchers classified Americans based on a few demographic characteristics—race, county of residence, income, population density, and homicide rate in their locale. Using data from the National Census, and from the Centers for Disease Control’s National Center for Health Statistics, they calculated life expectancy and death rates for the eight groups, each containing millions of Americans. They also compared the life expectancy for each gender within the groups.
The difference between people with the highest life expectancy (Asian women) and those with the lowest (high-risk urban black men) was a whopping 21 years. In fact, the 10 million Americans with the best health have one of the highest levels of life expectancy on record in the world, the authors write. In contrast, they say, “millions of Americans, distinctly identified by their sociodemographic characteristics and place of residence, have life expectancies that are similar to some low-income developing countries.”
The health disparities revealed in the study remained largely unchanged between 1982 and 2001.
Differences in race, income, access to health insurance or utilization of health care did not explain the inequalities. Rather, chronic diseases and injuries associated with known risk factors like alcohol use, smoking, obesity, and elevated blood pressure, cholesterol, and blood sugar were responsible for most of the gap. The results suggest that strategies to reduce health disparities should focus on mitigating these risk factors in the groups most affected by them.
The research was published this week in PLoS Medicine.
Oldest writing in Americas found at Mexican construction site
So you think you’ve waited a long time to be published in a top-level journal? Try waiting nearly 3,000 years—that’s how long it took for the writings of an unknown Mesoamerican scribe to appear in this week’s issue of Science.
The script, found on a stone tablet in Veracruz state in southern Mexico, is the oldest known example of writing in the New World. Based on artifacts unearthed with the stone, researchers date the writings to 900 B.C. That’s 400 years older than any previous examples of writing found in the Americas.
The international research team included anthropologist and ancient language expert Stephen Houston of Brown University in Providence, RI.
The tablet turned up in 1999 on a pile of debris left from road construction in Cascajal, near the ancient home of the Olmec civilization. First noticed and rescued by local workmen, the find eventually came to the attention of the Mexican authorities and the international community. The Olmecs were the first civilized inhabitants of Central America, centuries before the Mayans and Aztecs, and the new discovery credits them with originating written language in the region.
The face of the block is the size of a legal pad, but the stone measures five inches thick and weighs 26 pounds. The writing surface is smooth and slightly concave, and appears to have carried earlier carvings, which were later erased.
The symbols, 28 different ones in all, resemble insects, ears of corn, and fish, and are arranged in groups that suggest sentences, and in one case, a couplet. While clearly of Olmec origin, the script bears no resemblance to later writing systems found in the area, suggesting that it was a literary dead end.
With such a small snippet, the chance of deciphering the text or determining its function is low. "The significance of the find depends on whether more examples can be recovered and whether these can be salvaged by archaeologists rather than road builders,” the authors write.