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Friday, February 23, 2007

Dye in MRIs Risky For Kidney Patients

Federal health officials are warning doctors that certain types of metallic dye injected for MRI scans have been linked to a rare and dangerous skin disease in kidney patients.

More than two dozen dialysis patients in St. Louis over a four-year period contracted the unusual skin ailment, which causes burning and itching that can lead to discoloration and stiffening of the skin.

The Centers for Disease Control and Prevention investigated some of the cases last year and found that the illnesses were tied to a contrasting agent -- basically a metallic dye -- used for magnetic resonance imaging. The disease occurred in patients with advanced kidney disease who had undergone an MRI or a similar test.

"To the general public, it's not a big concern. But to somebody with kidney disease, we want to warn them not to get an MRI with the contrasting agent," CDC spokeswoman Jennifer Morcone said.

The dyes in question contain gadolinium and are used in MRI scans that provide detailed pictures of internal organs and in similar scans that image blood vessels. The contrasting agents have been on the market since 1988.

Muslim Tile Patterns Show Math Prowess

Sophisticated geometric patterns in medieval Islamic architecture indicate their designers achieved a mathematical breakthrough 500 years earlier than Western scholars, scientists said yesterday.

By the 15th century, decorative tile patterns on the buildings reached such complexity that a small number boasted what seem to be "quasicrystalline" designs, Harvard University's Peter J. Lu and Princeton University's Paul J. Steinhardt wrote in the journal Science.

In the 1970s, British mathematician and cosmologist Roger Penrose became the first to describe these geometric designs in the West. Quasicrystalline patterns comprise a set of interlocking units whose pattern never repeats, even when extended infinitely in all directions, and possesses a special form of symmetry.

"Oh, it's absolutely stunning," Lu said in an interview. "They made tilings that reflect mathematics that were so sophisticated that we didn't figure it out until the last 20 or 30 years."

Lu and Steinhardt cite designs on the Darb-i Imam shrine in Isfahan, Iran, built in 1453.

Lu said the revelations suggest that Islamic culture was even more advanced than was previously thought.

Deep-Sea Sharks Land on Watch List

Scientists yesterday added several species of deep-sea sharks to the World Conservation Union's Red List because of overfishing.

At a meeting in Oxford, England, the scientists listed all three species of thresher sharks as "vulnerable globally," and moved the shortfin mako to "vulnerable today" from "near threatened."

The scientists decided that the blue shark, the world's most abundant and heavily fished pelagic shark, should remain in the "near threatened" category despite a decline in numbers of 50 percent to 70 percent in the North Atlantic and scant conservation measures.

Scientists later added the semi-pelagic scalloped hammerhead shark to the "endangered" category, while the pelagic stingray was put in the "least concern" category.

-- From News Services


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