Editor's note: Science Scan is a roundup of recently published biotechnology-relevant research.

A posse of rogue brain neurons seems to provoke epileptic seizures, French neurosurgeons report in a study that may help researchers develop more effective therapies for treating epilepsy.

This disorder afflicts 1 percent to 2 percent of the world's population. It's triggered by synchronized hyperactivity in certain regions of the brain. The paper in the Nov. 15, 2002, Science bears the title: "On the origin of interictal activity in human temporal lobe epilepsy in vitro." The article's authors are neurosurgeons at the Pitié-Salp trière hospital in Paris.

They analyzed neuronal activity recorded from slices of brain tissue removed therapeutically from 21 patients with temporal lobe epilepsy. The specimens revealed a series of synchronized spontaneous, rhythmic discharges initiated in an output zone of the hippocampus, called the subiculum. They seemed to be induced by a neurotransmitter that normally inhibits such activity. The discharges were suppressed by antagonists of either glutamatergic or gamma-aminobutyric acid (GABA) signaling. The authors suggest that these hyperactive neurons may thus be functioning as "pacemaker cells" that help initiate seizures. The specific events leading up to epileptic discharges are largely unknown. A similar phenomenon has been observed only during a period of early brain development.

Temporal lobe epilepsy is the most frequent and severe form of adult focal epilepsy. It is usually refractory to drug therapy and often is associated with certain regions of the hippocampus. Their paper concludes: "Understanding changes in the subiculum induced by the loss of excitatory inputs from CA1 hippocampal cells may eventually provide therapeutic avenues for preventing seizure development after hippocampal insults."

An accompanying editorial titled "GABA becomes exciting" makes the point that "pharmacological interventions for the treatment of epilepsy rely principally on drugs that reduce cellular excitability or that modulate synaptic communication, usually by enhancing the activity of inhibitory GABA receptors."

Genetically Engineered Food Crops Could Enhance Nutritional Benefits

Genetic engineering of food plants could increase their ability to withstand global warming while also enhancing their disease-fighting benefits for people. The key to this twofold benefit is augmenting the antioxidant content of crops.

In humans, antioxidants help protect against a panoply of ills - various cancers, age-related macular degeneration, heart disease, asthma, multiple sclerosis, rheumatoid arthritis, dyslexia, attention deficit/hyperactivity disorder, depression and schizophrenia - according to a broad range of studies. Antioxidants function by scavenging damaging forms of reactive oxygen species (ROS), which also helps plants dissipate excess solar energy during extremes of heat or drought.

A paper on this subject in Science dated Dec. 13, 2002, is titled "Antioxidants in photosynthesis and human nutrition." Its authors are organismic biologists at the University of Colorado. Their research recommends that people consume more carotenoids, which are found in many brightly colored fruits and vegetables, notably tomatoes.

Their paper leads off by recalling, "The harnessing of solar energy depends on a safety valve that effectively eliminates hazardous excess energy and prevents oxidative damage to the plant cells." It makes the point, "Many of the compounds that protect plant cells also protect human cells. The pathways that synthesize these compounds are becoming amenable to genetic manipulation, which may lead to improved physical and mental health."

Hepatitis C, Calicivirus, West Nile Viruses Succumb To AVI's Antisense Antiviral Drug

Norwalk virus, which visited acute digestive disorders on hundreds of cruise ship passengers in recent weeks, is thought to be a species of Calicivirus, a source of severe gastroenteritis. Together with West Nile and hepatitis C viruses, it's the subject of an announcement on Dec. 5, 2002, by AVI BioPharma Inc., of Portland, Ore.

The press-released report updated its preclinical results from targeting single-stranded RNA viruses with the company's proprietary Neugene antisense drug. "The significant amount of attention now being focused on viruses in our environment, both naturally occurring viruses and those with the potential for being used in biological warfare," said Patrick Iversen, AVI's senior vice president of R&D, "parallels AVI's ongoing emphasis on the use of Neugene compounds as antiviral drugs."

AVI recently treated three Humboldt penguins at the Milwaukee County Zoo, suffering from a natural outbreak of West Nile, which attacks birds selectively. Since treatment with Neugene antisense drugs, all three penguins had survived for over a month and a half. "This positive outcome," Iversen observed, "differs from that of 10 flockmates, which died from West Nile virus at the same zoo, as reported in the Wisconsin State Journal dated Oct. 4, 2002."

Jointly with XTL Pharmaceuticals Ltd., of Rehovot, Israel, AVI used a proprietary animal model to evaluate antisense efficacy in treating active hepatitis C virus infections, with positive results from Neugene. AVI plans clinical trials against HCV in 2003.

It's A Dead Heat Between Morning-After' Contraceptive Hormones, As Found By WHO

"Which Pill?" is the dilemma that confronts women or girls who urgently need contraception after sexual intercourse. An international survey in The Lancet dated Dec. 7, 2002, finds that hormone treatment with a single dose of mefipristone (RU-486) or two of levonorgestrel 12 hours apart are equally effective for "morning-after" protection after unprotected sex. The report is titled: "Low dose mefipristone and two regimens of levonorgestrel for emergency contraception: a WHO multicenter randomized trial."

The trial canvassed 15 family-planning clinics in 10 countries, enrolling 4,136 healthy women with regular menstrual cycles who requested emergency contraception within five days of unprotected sexual intercourse.