Reevaluating risk factors. According to Deborah Frank, associate professor of pediatrics at the Boston University School of Medicine, the widespread belief that cocaine use during pregnancy results in permanent damage to a child's development is inaccurate, based on uncritical reading of studies that were not in accord with the principles of careful science.

Frank and her colleagues at the BU Schools of Medicine and Public Health reevaluated data from 36 studies dating back to 1984. They reviewed the physical growth, cognitive abilities, language skills, motor skills, and behavior of children with prenatal exposure to cocaine. The researchers found no consistent negative association between prenatal cocaine exposure and physical growth, developmental test scores, or receptive or expressive language. The study suggests that prenatal exposure to tobacco, marijuana, or alcohol, as well as the quality of the child's postnatal environment, may contribute more to developmental impairments than cocaine exposure.

"As rates of cocaine addiction soared in the late 1980s and early 1990s, the media described these children as 'doomed,' a biologic underclass of children unable to learn or love," Frank says. "That is simply not the case. In fact, the research suggests that poverty plays a much more destructive role in these children's lives than prenatal cocaine exposure."

The study appeared in the March 27 issue of the Journal of the American Medical Association.

Finding the perfect match. Researchers routinely use gel-based hybridization technologies to compare DNA sequences, which is a slow and tedious process. Chip-based microarray technologies now under development are expected to speed up the process, allowing hundreds, even thousands, of comparisons on a single chip. But the new technologies, dependent upon complex procedures to immobilize DNA, also require long incubation times and fluorescent or radioactive labeling. These methods also tend to produce mismatched hybrids, or "false positives," according to CAS Assistant Professor of Chemistry Rosina Georgiadis. And, she adds, none of these approaches allows you to see what is happening on a molecular level during the process, in real time.

Georgiadis, CAS Research Associate Richard Heaton, and graduate students Alexander Peterson (GRS'02) and Lauren Wolf (GRS'04), a presidential university graduate fellow, have developed an alternative. Their novel laser-based tool, called optical surface plasmon resonance spectroscopy (SPR), allows them to observe DNA hybridization in action. A digital camera, filming through the back of the chip, records the target DNA as it attaches itself to probes immobilized on a thin layer of gold on the opposite surface.

The researchers have been granted a provisional patent on a further modification of this technique, called electrostatic SPR, that eliminates the need for labeling while significantly increasing the speed and accuracy of hybridization. Electrostatic SPR exploits the negatively charged phosphate backbone of DNA.

When a positive electric field is created on the surface of the chip, potential DNA matches are attracted to the probes. Subsequently reversing the field repels all but the strongest matches, leaving only those that are perfect hybrids. The entire process takes minutes rather than hours, and is also effective in examining how molecules and proteins bind with DNA, making it an ideal tool for pharmaceutical research and the development of new diagnostic tools.

Having proved these concepts for single DNA targets, Georgiadis has recently received National Science Foundation funding to extend the process to an array mode, measuring hybridization for multiple targets at once. She and her group have also recently received National Institutes of Health funding to use electrostatic SPR to better understand the mechanisms of a new anticancer drug now in phase II clinical trials.

A paper detailing electrostatic SPR appeared in a recent issue of Proceedings of the National Academy of Science.