CLEVER CRICKET

In an innovation that could be useful in making sure, say, that a helpful household robot doesn’t knock over lamps while you’re away from home, MIT researchers have invented and refined a positioning system that works well inside buildings, among other venues. The system, called Cricket, is a counterpart to the Global Positioning System, which provides good positioning services in many locations but doesn’t work very well indoors. Cricket features wall-mounted “beacons” that put out both radio and ultrasonic signals. Receivers mounted elsewhere in the room — for example, on that helpful robot — can, by comparing the signals, allow for positioning calculations that are extremely accurate, says Hari Balakrishnan, MIT associate professor and member of the Computer Science and Artificial Intelligence Laboratory. The system could also help something like a robot plot directions in moving around a space. Cricket, which has been released for commercial use, was developed as part of Project Oxygen, CSAIL’s ambitious effort to make computer technologies a more convenient and readily usable part of our

CAUTION ON GINSENG

Studies have shown ginseng sometimes has one of the benefits that marketers claim for it — promoting wound-healing — but at other times it has just the opposite effect. Now an international group led by an MIT biological engineer has found out why: the make-up of ginseng can vary chemically. The researchers are from England, the Netherlands, and Hong Kong as well as the U.S. The group, headed by MIT postdoctoral associate Shiladitya Sengupta, tested ginseng samples from four different countries in the lab. All had varying amounts of specific natural chemicals the group had identified as potentially active in the body. The researchers found that if one of those ingredients was more common, the ginseng promoted wound healing. If the other ingredient predominated, the effect was the opposite.“We found that this proportion really affected the ultimate impact of the ginseng,” says Sengupta, a member of the MIT biological engineering division. The study may open the way for new therapies, including treatments for those, like diabetics, who are prone to developing wounds. At the same time, it raises a caution flag, says Ram Sasisekharan, professor of biological engineering and head of the lab where Sengupta works. “This is a very clear example of why we need regulations standardizing herbal therapies through compositional analysis,” says the faculty member.

MENDING HEARTS

Work at MIT has for the first time led to engineered heart tissue which has a lot in common with its natural counterpart, including the ability to contract. “We’ve been trying to engineer a patch of tissue that has the same properties as native heart tissue, or myocardium, and that could be attached over injured myocardium,” says Gordana Vunjak-Novakovic, a principal research scientist in the Harvard-MIT Division of Health Sciences and Technology and the leader of the research team. The group’s approach involved seeding a 3-D polymer scaffold with cardiac cells from a rodent. The scaffold is designed to gradually melt away as the cells grow and divide, and did so. The researchers then treated the resulting chunk of tissue, which was about the size of a dime, with electrical signals that mimicked those in a normal heart — a step that turned out to be crucial to converting the cell-originated tissue into something close to that in a real heart. The group’s next efforts will focus on creating tissues thick enough to serve as patches for actual hearts. The progress made to date, though, is noteworthy in its own right, says Robert Langer, professor of biological engineering and member of the team along with other investigators from MIT, and researchers from Harvard and the University of Wisconsin. (The lead author on the report was Milica Radisic, a post-doctoral associate in Vunjak-Novakovic’s lab.) “The real advance here is that we mimicked what the body does itself, and got it to work,” says Langer.

MAGNESIUM AND MEMORY

Magnesium is a crucial nutrient for humans. And while we don’t need much — 400 milligrams is the current daily requirement — those who get too little are known to be at risk for allergies, asthma, and heart disease, among other conditions. MIT researchers now may have added another deficiency to that list: memory loss. In lab studies, a group led by Guosong Liu found that magnesium — which is harbored by dark, leafy vegetables like spinach — is crucial for sustaining a quality known as plasticity in brain cells. And how does this relate to memory? Plasticity means the ability to change and evolve, and that’s what cells in memory parts of the brain do when we’re forming new memories, says Liu, an associate professor of brain and cognitive sciences. If there’s not enough magnesium reaching neurons, the effect is to limit the ability of a key cellular molecule to do its job. The result, in turn, is limitations on that cell’s plasticity. By contrast, says Liu, in his group’s studies, “increasing the concentration of magnesium, with other changes, led to the largest increases in plasticity ever reported in the scientific literature.” The work is significant because of its potential for opening the way for new approaches to memory loss, says Liu. It also points up the need to make sure that all of us get ample amounts of magnesium in our diets.