SCIENCE

Guns are used in five percent of suicide attempts, but more than 90 percent of those attempts are fatal. Drugs account for nearly 75 percent of suicide attempts, but the fatality rate in those attempts is less than 3 percent.

"Removing all firearms from one's home is one of the most effective and straightforward steps that household decision-makers can take to reduce the risk of suicide," Miller said in a statement. "Short of removing all firearms, the next best thing is to make sure that all guns in homes are very securely locked up and stored separately from secured ammunition.

"In a nation where more than half of all suicides are gun suicides and where more than one in three homes have firearms, one cannot talk about suicide without talking about guns."

-- Shankar Vedantam

Researchers Report Success In Using Plants to Make Vaccines

Making vaccines is tricky. Part of the challenge is that the material -- eggs, animal cells, yeast -- in which the vaccine material is grown can be very finicky to handle. Researchers last week reported success in making a vaccine in two distinctly unusual hosts -- tobacco plants and collard greens.

Scientists at Thomas Jefferson University in Philadelphia made a new vaccine against smallpox. The original smallpox vaccine (which permitted eradication of the disease in the 1970s) was a weakened version of vaccinia virus that provided immunity against smallpox when scratched under the skin.

The new vaccine consists of a vaccinia protein called B5. In the case of the collards, gene-containing plasmids were sprayed on the leaves, which then absorbed the B5 gene and made the protein. The tobacco plants, on the other hand, were genetically engineered to produce B5 protein from the start.

After harvesting the plants, the researchers gave the vaccine to lab mice through three routes. Some animals were fed pellets made from collard greens, some had purified B5 sprayed up their noses and others had the protein injected. The animals that ate the vaccine got no protection. Those that got it in the nose developed a mild antibody response. The mice receiving the injected vaccine, however, had a vigorous immune response. They survived infection with vaccinia virus that was fatal in unvaccinated animals.

This was not the first time that plants have been used to produce experimental vaccines. But it adds to the evidence that those low-maintenance hosts may make useful products. The federal government is stockpiling old-style smallpox vaccine as part of the national defense against a bioterrorism attack.

The study appeared in the Proceedings of the National Academy of Sciences. The research was directed by Hilary Koprowski, a longtime vaccinologist who developed the first polio vaccine used in human trials in the 1950s and later improved the rabies vaccine.

-- David Brown