A May 24 Science Notebook item described a newly discovered asteroid that circles the sun in 184 days as having the fastest orbit of any known object in the solar system. It has the fastest orbit of any non-planetary object, but Mercury orbits the sun in 88 days. (Published 06/04/04).

Small, Speedy Asteroid

Detected Inside Earth's Orbit

Astronomers at Lowell Observatory have discovered an asteroid inside Earth's orbit that rockets around the sun once every 184 days -- the quickest trip of any known object in the solar system.

Lowell research assistant Brian Skiff observed the object known as "2004 JG6" on May 10, in the early evening during a brief window of time when objects close to the sun are visible. Skiff said the asteroid will also be relatively easy to see just after sunrise in autumn.

"They're only lit up on the back side, so that if you saw one during the day, it would only be a tiny crescent," Skiff said in an interview from the Flagstaff, Ariz., observatory. "When you look outward away from the sun, objects are lit up all the time."

Skiff discovered the asteroid in conjunction with the Lowell Observatory Near Earth Object Search, part of a nationwide search to find all the asteroids and comets that could possibly collide with Earth.

Skiff said 2004 JG6 has an elliptical orbit and scoots past the sun at a distance of 27 million miles -- inside Mercury's orbit -- at its closest point. It then arches out beyond Venus until it is 90 million miles away, only 3 million miles inside Earth's orbit.

"It's no danger to us, at least not for the next 10,000 years," Skiff said.

Based on its distance from Earth and the amount of light it reflects, Skiff estimated the asteroid is between three-tenths and sixth-tenths of a mile in diameter. It is hurtling through the heavens at 67,000 mph. Earth moves through space at about 40,000 mph.

-- Guy Gugliotta

Two Techniques Combined

To Treat Spinal Cord Injury

Two techniques that had been previously developed to treat spinal cord injury in animals work effectively when combined, allowing deliberately injured rats to regain a certain amount of mobility, researchers say.

Although several steps remain before researchers can begin to consider testing the technique in people, a top government researcher said the advance is "very important."

"The animals were able to balance their weight, place their feet and walk around in a way that shows messages are working their way down to their legs," said Naomi Kleitman, program director in spinal cord injury at the National Institute of Neurological Disorders and Stroke.

One technique involves transplanting special cells called Schwann cells to bridge damaged spinal cord tissue. The other involves administering a substance called cyclic adenosine monophosphate (cAMP), which helps nerve cells regenerate. The new study showed that the two techniques work well together.

Kleitman described the restored function in the rats as "a little miracle." Other research groups have also shown improvements in animal studies of spinal cord injury, but Kleitman said it was difficult to compare the different results. She said the new result would have to be reproduced and scientists would have to evaluate the optimal dose and timing of the techniques before they could consider human testing.

The study was conducted by researchers at the Miami Project to Cure Paralysis at the University of Miami School of Medicine, the University of Sao Paulo in Brazil and Hunter College in New York. . It was published in Nature Medicine.

-- Shankar Vedantam

New Fertility Technique May

Produce Genetic Abnormalities

An experimental baby-making technique being used by some fertility clinics can produce embryos with severe chromosomal abnormalities, and its use should be severely limited, according to new research from an international team of doctors and scientists.

The technique, "round spermatid injection," or ROSI, is sometimes attempted when a man has a condition that prevents him from making mature sperm. Doctors retrieve from the testes a few immature sperm, called round spermatids, and inject them directly into a woman's egg in a laboratory dish. Resulting embryos can be transferred to the woman's uterus to develop into a baby.

Although many such efforts -- and a few births -- have been reported, success rates have been extremely low. And questions have lingered as to whether ROSI babies might be at added risk of genetic problems, since the male genes in round spermatids may not have undergone the full array of molecular processing that typically occurs in a maturing sperm cell.

The new study, described in the May issue of Fertility and Sterility, used sophisticated tests to look for chromosomal abnormalities in ROSI embryos created in Turkish fertility clinics. Of 143 attempts to make embryos by ROSI, about two-thirds did not develop at all after fertilization, a sign of probable genetic problems. But even among those that developed to varying degrees in laboratory dishes, serious chromosomal abnormalities were nearly twice as common as average. Among the problems were missing chromosomes, multiple copies of chromosomes, and fragmented DNA.

Although 11 embryos were transferred to women's wombs, none of the women became pregnant. The results, the report concludes, "suggest that ROSI at this stage should not be offered as a useful technique in assisted reproduction."

-- Rick Weiss