Gene Therapy Progresses a Hair

Scientists have been struggling for years to find a way to cure human diseases by giving people new genes. The field recently suffered a major setback when a young Tucson man died while participating in a gene therapy experiment at the University of Pennsylvania.

At the same time, researchers have also been looking for other uses for gene therapy. And now, a team of scientists in Philadelphia has taken what could be a step toward using gene therapy to permanently color gray hair.

Kyonggeun Yoon of Thomas Jefferson University and colleagues showed they could restore pigmentation to the hairs of albino mice by correcting a defect in a gene in the hair follicle. A few weeks after the researchers applied corrective DNA to the mice, either topically or by skin injection, the animals grew a small number of pigmented hairs. The pigmentation lasted only about three months, however.

Although the work remains far from providing a way to permanently restore color to gray hair in people, it shows that such a thing may at least be possible, the researchers said.

"Gene therapy has just taken a cosmetic step forward," wrote Robert M. Hoffman of AntiCancer Inc. of San Diego in an article accompanying the research in the January issue of the journal Nature Biotechnology. "Hair follicle research is an area that not only holds great scientific interest, but also has enormous commercial potential. This study now demonstrates that the hair follicle is a visible, safe, and non-invasive target for gene therapy, which is a field that recently has suffered unfortunate setbacks in the safety of its medical applications."

Sex and the Brain's Anatomy

Brain scientists at Johns Hopkins have found new evidence for how the brains of men and women differ.

Godfrey Pearlson and colleagues used brain scans to study 15 men and women, focusing on a part of the brain known as the inferior parietal lobule, which is involved in visualizing things in three dimensions and solving mathematical problems.

Overall, men tended to have larger inferior parietal lobules than women, the researchers report in the current issue of the journal Cerebral Cortex. The right side of this part of the brain tends to be larger in women while men have larger left sides. The right side of this brain section is associated with working memory of spatial relationships and the ability to sense relationships between body parts and awareness of a person's feelings. In contrast, the left side is more involved in perception, such as judging how fast something is moving, estimating time and the ability to mentally rotate three-dimensional objects.

Unintended Aid to Salmonella?

In the 1980s, health officials in Europe and the United States realized there had been a sharp increase in food poisoning caused by a type of salmonella bacterium found in chickens, eggs and egg products. The upsurge caused concern that perhaps modern farming techniques were to blame.

Now scientists have proposed a new theory: A more virulent strain of salmonella was given a chance to flourish in poultry after less serious forms were killed off with antibiotics.

Andreas J. Baumier of the Texas A&M University Health Science Center in Texas and colleagues reviewed the scientific literature and concluded that a strain of salmonella called S. enteritidis flourished after strains called S. pullorum and S. gallinarum were eradicated from domesticated flocks of birds beginning in the 1930s. The birds then may have become infected with the S. enteritidis strain from mice and rats making their way into henhouses.

"The increased incidence of salmonellosis in humans may have been caused by S. enteritidis filling the ecological niche vacated by eradication of the avian pathogens," the researchers wrote in the Jan. 7 issue of Science, which was released last week.

A Hormone's Impact on Appetite

Ever since researchers identified the appetite-regulating hormone leptin in 1994, they've been trying to figure out exactly how it works in the hopes of finding new ways to control obesity. Scientists have now found evidence that leptin works through the brain's pleasure center, perhaps making us enjoy food less and enjoy activities that burn calories more.

Peter Shizgal of Concordia University in Montreal and colleagues studied rats that were hooked up to a system that allowed the animals to stimulate different parts of their brains. When the rats received injections of leptin, they were less likely to stimulate reward circuits that the could activate when deprived of food. Leptin also appears to enhance the animals' sensitivity to activation of other parts of the brain that did not respond to food deprivation.

"Leptin could make complementary contributions to energy balance by reducing food reward while enhancing the value of behaviors incompatible with feeding," the researchers wrote in the Jan. 7 issue of Science.

Bioengineering Silkworms

A team of researchers from France, the United States and Japan has found a way to insert foreign genes into the genetic blueprint of silkworms.

The team used a type of DNA known as "piggBac" to introduce a gene that produces a fluorescent green protein into silkworm embryos. Nearly 2 percent of the worms that resulted contained copies of the foreign gene. Moreover, the gene was passed on to later generations.

The work suggests that it may be possible to genetically engineer silkworms to produce silk with certain desired traits, such as stronger silk to make bulletproof vests or more reliable parachutes.

"The textile industry could . . . benefit from novel fibers made by silkworms transformed with various genes encoding fibrous proteins," the researchers wrote in the January issue of Nature Biotechnology.