Buffinton's research seeks to answer questions about stressed hearts, broken bones and diseased arteries. Her academic home, however, is in mechanical engineering, not biology.

Christine Buffinton

Christine Buffinton's research seeks to answer questions about stressed hearts, broken bones and diseased arteries. Her academic home, however, is in mechanical engineering, not biology.

"I liked both biology and engineering," says the new assistant professor of mechanical engineering. Instead of choosing, she combined the two. In her research, Buffinton applies the principals and techniques of mechanical engineering to medical quandaries.

To better understand how the heart develops and responds to changes in blood pressure, Buffinton has studied embryonic chicken hearts. "We used chicken eggs as our experimental model because they are not attached to a mother, like a mouse or other models," she says. Buffinton could open an egg, do microsurgery, close the egg, put it back in the incubator, and let it grow to another stage to see the effects over time of her manipulation.

Based on her work with the developing eggs, Buffinton has developed a computer model of the embryonic heart. "It's a finite element model that predicts the stress and strain everywhere 3-dimensionally through the heart," she says. "We can section it virtually so we can see the size and shape of the cavities and also look inside at stresses and strains."

The equations that make up the model are so complicated that it takes two to three days to solve on a computer. The answers are worth waiting for. Buffinton can tweak factors in the computerized heart, such as a muscle not contracting the way it should or a stretched chamber wall, and see the effects.

Many cells in the body respond to mechanical forces, and Buffinton's model is helping her understand how the heart responds to mechanical factors, such as blood pressure. Muscles, as we know, increase in size with exercise. In the heart, Buffinton has found that creating an artificially high blood pressure causes the entire organ to become larger and stiffer, and creates ventricular septal defects, or holes in the walls that divide the chambers of the heart. Buffinton's goal is to understand the underlying system that controls these responses to mechanical factors.

Such an understanding could guide heart disease treatments. Heart tissue does not regenerate, so medical research is exploring the use of injected stem cells to grow new heart tissue or blood vessels. Buffinton's model may help determine the best conditions for stem cell growth.

Buffinton also has worked with her students to look at the effects of different ways of using a plate to hold broken leg bones in place. She is starting a new study of how plaque — the deposits of cholesterol and other substances that lead to coronary artery disease — affect arteries. The model she plans to create will reflect the mechanical properties of arteries, and help doctors understand the overall effect of treatments such as balloon angioplasty or stents

Posted Sept. 22, 2009

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