American Scientist

This roundup summarizes some notable recent items about scientific research, selected from news reports compiled in Sigma Xi's free electronic newsletters.

Deciphering a Lost Technology

For more than a century, scholars have puzzled over the remains of a strange object recovered from a Roman shipwreck off Greece, a geared device dubbed the Antikythera Mechanism, which is believed to date from the late second century B.C. Using high-resolution x-ray tomography to probe the surviving pieces, a team of astronomers, archaeologists and technologists have shed more light on the nature of this intriguing artifact, which at one time was able to predict lunar and solar eclipses and may have also been used to display the positions of planets. The Antikythera Mechanism is considerably more complex than anything known to have been built in the millennium that followed its construction.

Freeth, T., et al. Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism. Nature 444:587-591 (November 30, 2006)

Muscular Dystrophy Reversed

Duchenne muscular dystrophy, a genetic disease that causes progressive paralysis, often results in death before age 30. Currently, there is no effective treatment. But investigators have recently demonstrated what may be a promising approach using dogs suffering from an analogous disease: golden retriever muscular dystrophy. Afflicted retrievers were infused with a type of vessel-associated stem cell called mesoangioblasts. The animals treated with such cells taken from normal dogs showed marked improvements in muscle-contraction force and, in many instances, the preservation of their ability to walk. Thus it is reasonable to hope that similar mesoangioblasts may one day provide a stem-cell therapy in people suffering Duchenne muscular dystrophy.

Sampaolesi, M., et al. Mesoangioblast stem cells ameliorate muscle function in dystrophic dogs. Nature 444:574-579 (November 30, 2006)

Then There Was Light

On January 18, 2000, an exceptionally bright meteor lit up the dawn sky over Canada's Yukon and Northwest Territories along with parts of British Columbia and Alaska. Fragments of the 200,000-kilogram mass that created this fireball landed on the frozen surface of the Yukon's Tagish Lake, where they were later collected. The subzero temperatures, along with careful collection techniques, allowed the recovery of volatile compounds from this meteorite—a very primitive type known as a carbonaceous chondrite. An isotopic analysis of organic globules contained in some of these otherworldly samples reveals that they formed at very low temperatures, probably within the cold molecular cloud that later gave rise to the solar system.

Nakamura-Messenger, K., et al. Organic globules in the Tagish Lake meteorite: Remnants of the protosolar disk. Science 314:1439-1442 (December 1, 2006)

Put Down That Sunscreen

Scientists have long known that the incidence of multiple sclerosis, an autoimmune disease, is higher in northern portions of the United States than in the South. Now clues are emerging as to why this regional variation exists. A key risk factor may be low levels of vitamin D, which is produced naturally when skin is exposed to sunlight. One of the properties of vitamin D is to suppress immune response, so it makes sense that people deficient in this substance may be more prone to suffer from an autoimmune disease. Investigators confirmed this association using Army and Navy records of physical disability to identify patients with multiple sclerosis and then examined blood samples taken earlier and stored in the Department of Defense Serum Repository.

Munger, K. L., et al. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. Journal of the American Medical Association 296:2832-2838 (December 20, 2006)

Medieval Murder Mystery

The circumstances surrounding the sudden and simultaneous deaths of Francesco I de' Medici and his wife Bianca Cappello in 1587 have long suggested foul play—in particular the possibility that they were poisoned by Francesco's brother, Cardinal Ferdinando, who may have hoped that their deaths would allow him to become the next Grand Duke of Tuscany. A new analysis of the couple's remains shows high arsenic concentrations in soft tissue samples but low values in Francesco's femur and beard hair, ruling out the possibility of chronic arsenic exposure and indicating that they probably suffered acute arsenic poisoning. Cardinal Ferdinando was not available for comment.

Mari, F., et al.The mysterious death of Francesco I de' Medici and Bianca Cappello: an arsenic murder? British Medical Journal 333:1299-1301 (December 23-30, 2006)

Another Cause of Alzheimer's

In 1993, investigators fingered the ApoE4 gene as a cause of late-onset Alzheimer's disease. Yet that gene could account for only about half of the cases of this devastating brain disorder, which afflicts many elderly people. Now another culprit has been identified: a variant of the SORL1 receptor. The team that made the discovery included members from Columbia University Medical Center, which is located in the Washington Heights neighborhood of upper Manhattan. The Columbia University investigators noticed that Dominicans living in Washington Heights suffered from Alzheimer's at a rate about three times that found for the general population. That clue prompted the collection of medical histories and blood samples from Dominican families, allowing identification of the problematic variant, which has since been found to exist in several other populations.

Rogaeva, E., et al.The neuronal sortilin-related receptor SORL1 is genetically associated with Alzheimer disease. Nature Genetics (January 14 advance online edition)