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Mary Davis. Photo: Kelvin Ma


Diesel Fume Dangers

“Over the last ten years, I’ve been involved in a group that is studying the link between diesel exhaust and lung cancer in the trucking industry. The special danger of diesel is that particles in the exhaust are very small, and can reach the deepest regions of your lungs, where they can enter your bloodstream. Attached to those particles are known carcinogens.

Until recently, though, it’s been hard to tell definitively if diesel causes lung cancer. Why? Because calculating peoples’ exposure over their lifetime is a challenge. To solve that problem, my colleagues and I took thousands of air samples at truck depots around the country. We compared that data to measurements that the U.S. government took in the early 1980s, and then extrapolated between the two to get an exposure estimate for those sites over thirty years. Then we looked at the medical history of fifty-five thousand workers in the trucking industry. It turned out that people who had higher exposure to diesel, like truck drivers, died of lung cancer much more often than workers with lower exposure, like office managers. I’ m proud to say that, based in part on our analysis, the World Health Organization upgraded diesel exhaust from a ‘probable’ carcinogen to a ‘known’ carcinogen in 2012.”

—Mary Davis, associate professor, Urban and Environmental Policy and Planning

Drug-Resistant Bacteria

“My colleagues and I have found definitive links between the use of antibiotics on industrial farms and the rise of drug-resistant bacteria. U.S. farmers mix antibiotics into their feedstock to promote growth and prevent disease in animals. That kills off most of the bacteria in those animals, but leaves behind some that have mutated or evolved to resist the drug’s effects. The more animals that ingest those drugs, the higher the chance that resistant strains of bacteria like Salmonella and E. coli will form. Those can cause infections in humans that are difficult to treat, and can be life-threatening.

Industrial farms aren’t the only problem, though. Many doctors overprescribe antibiotics, which also encourages the emergence of resistant strains. The first case of drug-resistant gonorrhea was just reported in North America, and threatens to become a major public health problem.

So how do we solve this? Well, first, we’ve got to remove antibiotics used for growth promotion from industrial farming. Second, we need to be more cautious about how we use antibiotics on people. And third, we need to understand the mechanisms that cause bacteria to become resistant. Our laboratory is working on that right now—if we can define the basic mechanisms of resistance, we can develop drugs that can work around them.”

—Stuart Levy, director of the Tufts University Center for Adaptation Genetics and Drug Resistance

The “Other” Fat

“When you think of ‘fat,’ you probably think of white fat, the substance that fills out our bellies. But there’s also something called brown fat. Unlike white fat cells, which store fatty acids, brown fat cells actually metabolize, or burn up, those acids.

There’s a lot of interest in the medical community about harnessing the power of brown fat— if we can create a drug that activates it, we might help control obesity. We might also be able to control type 2 diabetes, which can stem from obesity.

My lab is looking into what causes brown fat to turn on at a molecular level. We study a protein called perilipin, which normally inhibits fat breakdown. When your nervous system activates brown fat cells, however, it sends out signaling molecules called catecholamines that alter perilipin’s chemical structure. The perilipin then starts binding with other proteins that are used to break down fat.

Our lab first identified perilipin’s role in this process back in 2007, and we’re now trying to figure out exactly how it works. Which proteins does it recruit to break down fat? What are the molecular details of the process? Those are the next big questions.”

—Andrew Greenberg, senior scientist and director, Obesity and Metabolism Laboratory, Jean Mayor USDA Human Nutrition Research Center on Aging

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