Rounding the finish of a good run

By Jessica Fujimori, MIT News correspondent

Early Sunday mornings, when the streets of Cambridge are still empty, you might find MIT senior Justin Bullock running one of his favorite loops: down Memorial Drive along the Charles River, through the woods at Fresh Pond Reservation, and back down Massachusetts Avenue to his dorm, Burton Conner.

Bullock's morning runs are the start to busy days: A chemical engineering major who's also earning a concentration in Spanish language and literature, Bullock has done research in two labs, co-authored a paper, volunteered at a hospital in Mexico, and captained three varsity teams during his four years at MIT.

His interest in science began early and was encouraged by his mother, a high-school chemistry teacher who raised Bullock and his two older sisters in Detroit. His father was incarcerated from when Bullock was in third grade until after his high-school graduation. "My mom always made us feel like there wasn't anything missing," Bullock says. "She made it so I was really OK."

Education was always a priority in their family. "All my friends would be outside running around playing; we'd be inside doing homework, and then we'd go outside afterward," Bullock recalls.

Bullock always enjoyed science, but his high-school classes in chemistry and anatomy and physiology really drew him in. When Bullock began looking at colleges, both academics and athletics were priorities; he had been playing soccer since he was 5 years old, and began running in high school. "I was looking at places that had good science and engineering programs, but also where I could run," he says. "MIT was kind of the perfect fit for me. I liked the fact that I could be competitive as a freshman but still have a lot of room to improve."

Speed, endurance, and community

Nearly every day of every semester, Bullock runs: cross country in the fall, indoor track in the winter, and outdoor track in the spring. He loves the clear correlation between what you put in and what you get out of running: "If you work harder, you will run faster," Bullock says. "Numbers are numbers; they don't lie." This spring, he ran the fastest 1500-meter on his team, at 3 minutes, 56 seconds. (His personal best is 3:55.)

But the most important part of running for Bullock is not the speed or the numbers; it's his teammates and his coach, Halston Taylor. "I feel like I've found a community through running," Bullock says. "A lot of my teammates are also my classmates, so I get to work with them on the field or track, but also in the classroom. There's a really special bond, I think, that you get from training or being around someone so much." Bullock's teammates elected him captain of the indoor and outdoor track teams during both his junior and senior years, and cross-country captain last fall.

Bullock has grown close with Taylor, as well. "I view him as a mentor, father figure," Bullock says. "I really talk to him about everything. I've always appreciated his insights, not just on running, but on life."

Quelling (antibiotic) resistance

In the lab, too, Bullock hit the ground running. As a freshman, through MIT's Undergraduate Research Opportunity Program, he joined the lab of assistant professor of chemistry Elizabeth Nolan.

In Nolan's lab, Bullock joined graduate student Tengfei Zheng to tackle a public health challenge: bacterial infections that develop resistance to antibiotics. These resistant cells might expel the drugs from inside, or not let them enter in the first place, curbing the medicine's efficacy. But what if the drugs could be disguised as something else — something the cell would actively uptake?

A molecule called enterobactin was a good shot. Bacterial cells use it to gather iron from their environment; they create it, secrete it, and then carry it back inside once it has bound iron. Zheng and Bullock wanted to use this molecule to smuggle in drugs that the cell might otherwise reject.

 "We were trying to use the enterobactin as a Trojan horse," Bullock says, "to use enterobactin as a transport vehicle to deliver antibiotics to [antibiotic-resistant] bacterial cells."

The first step was to see if the cells would accept enterobactin with any extra cargo. Zheng and Bullock tried adding various small molecules, and found that as long as the piggybacking add-ons were not too large, cells would still take in the entire package: enterobactin plus a sneaky small molecule. The results of their research were published in the Journal of the American Chemical Society during Bullock's junior year. The lab is now working on accomplishing delivery of real antibiotics in place of the small molecules used to test the concept.

Bullock currently works in the lab of Daniel G. Anderson, the Samuel A. Goldblith Associate Professor of Chemical Engineering, on a new project as part of a class, 10.29 (Biological Engineering Projects Laboratory). This time, the goal is to get insulin to diabetics when they need it — that is, when their blood contains high levels of glucose. Bullock, along with MIT juniors Mari Kordell and Kali Benavides, is helping to synthesize a polymer delivery system that will selectively release insulin into the body when a lot of glucose is present, controlling blood sugar levels.

Medicine in Mexico

Throughout his research and coursework in chemical engineering, Bullock weighed his options for the future. He had been considering medical school for some time, but two months spent volunteering at the Hospital General de Querétaro last summer solidified his resolve.

The government-run hospital, located in the central Mexican state of Querétaro, primarily serves patients without health insurance. "A lot of the patients the hospital saw were really poor, and that meant a lot of them had really bad health," Bullock says. "In addition to whatever illness they had, they also had a lot of other complications, from poor nutrition, for example."

Most of Bullock's time was spent working in the intensive care unit and emergency room, where he shadowed three nurses, none of whom spoke English. If I was struggling with a word, there was no way I could switch to English — I had to do it in Spanish," he says. "That was kind of tough at first, but ended up being really cool."

Bullock was working for the hospital's epidemiology department, where he helped to track patient infections.  "We wanted to know: If patients had an infection, did they get it from inside the hospital, or did they already have it coming into the hospital?" Bullock says.

To find the answer, the team would analyze cultures of bacteria from each infection, determining the unique identity of the bacteria based on their genetics and their resistance to drugs. Epidemiologists classify these identities by number, called "bio-numbers."

"It's very unlikely that two patients who are next door to each other [in the hospital] would obtain the same bacteria strain out in the community," Bullock says. "So by looking at bio-numbers, you can track infections within the hospital."

Bullock also enjoyed interviewing new patients to determine their recent diet and environmental conditions. "I really appreciated getting to interact with people," Bullock says. "It's really sad when you see someone getting worse over time, but it's also really cool when you see someone getting better over time."

After his experience working in the hospital in Querétaro, Bullock decided to pursue medicine as a profession: He will begin a five-year MD-MPH (master of public health) program at the University of California at San Francisco next fall.

Through his work at the hospital and in the lab, as well as his leadership on the track and cross-country teams, Bullock says, he has tried to positively impact the community around him.

"I think I've had a ton of people who have really helped me out, and I feel like the vast majority of my success is due to the fact that other people have been there and really supported me," he says. "I hope to pay that forward to other people. That's the thing that I'll try to achieve in my life."

Reprinted with permission of MIT News