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SCIENCE NOTES NEWS FROM BIOLOGY, MEDICINE

Survey shows amphibians are at risk of extinction

One-third of the world's frog and toad species are threatened with extinction, a new survey shows. For comparison, 23 percent of mammal species and 12 percent of bird species are similarly threatened.

Amphibians have been disappearing worldwide since at least the 1980s, but scientists haven't had a good idea of what is vanishing where. Now biologists have completed the Global Amphibian Assessment, the most detailed survey yet.

More than 1,850 amphibian species are threatened; 427 of those are critically endangered. At least nine and as many as 122 species have vanished since 1980, the researchers reported in Science. Some reasons include infectious diseases, vanishing habitat and environmental pollution.

-- Dallas Morning News

Reconstituted blood may work better for babies in surgery

Researchers have found that babies undergoing heart surgery do better with reconstituted blood than fresh whole blood.

When doctors used reconstituted blood, which is mixed from stored blood components, babies seemed to recover quicker than those who received fresh transfusions, scientists from the University of Texas Southwestern Medical Center at Dallas reported in the New England Journal of Medicine. This means shorter stays in the intensive care unit and on ventilators. Researchers examined 200 infants with heart birth defects who had surgery at Children's Medical Center Dallas. Reasons for the difference in outcome weren't examined.

-- Dallas Morning News

Type of schizophrenia appears to be linked to birth season

People who suffer from a particular form of schizophrenia are more likely to have been born in the early summer months than are others with the disease, a new study has found.

Schizophrenia is a devastating mental illness marked by delusions, hallucinations and so-called negative symptoms such as emotional flattening and inability to achieve at the level of peers. In one category of patients, those with what is known as deficit schizophrenia, the negative symptoms are especially pronounced.

The new report examined previous research from six countries in the Northern Hemisphere in which patients' deficit or nondeficit schizophrenia could be determined. The studies encompassed 1,594 patients. In all, patients with deficit schizophrenia were much more likely to have been born in June or July compared with other patients, whose births tended to occur more during winter months.

"This analysis supports the notion of a separate disease within schizophrenia," the authors concluded in the Archives of General Psychiatry.

-- Dallas Morning News

Scientists are surprised by traits of giant virus

The biggest virus ever discovered has scientists rethinking their definition of this type of germ. The virus, known as a Mimivirus, was discovered in a hospital cooling tower in England, but doesn't seem to cause any disease. It measures 400 nanometers in diameter, about 20 times the size of a cold virus.

And a team of French scientists who studied the virus's genes found some other surprises. All known viruses multiply by tricking the cells they infect to produce more virus particles. But the Mimivirus carries genes needed to make components of the virus, and in that respect, more closely resembles a parasite.

Writing in the journal Science, the researchers say scientists should search for more giant viruses to learn about how they evolved.

-- Dallas Morning News