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FACULTY SYMPOSIUM Faculty Give Alums Refresher CourseWhat we know about medicine today is far different from what we knew 50, 15, or even five years ago, so the medical curriculum is a particularly protean animal. The Faculty Symposium on June 7 gave alumni a glimpse of a few new medical trails they might follow if they were medical students today.
The genetic tendency toward storing fat for later use backfires when people live in a bountiful environment, says Jeffrey Flier. Photo by Justin Knight Fat ChanceJeffrey Flier, the George C. Reisman professor of medicine at Beth Israel Deaconess Medical Center, talked about the recent discovery of the leptin hormone and its role in obesity. "We're really facing an obesity epidemic," he said. "Obesity is a disorder of energy balance" in which the body makes use of fat cells' ability to store energy that has not been expended. The discovery of various genes that make humans susceptible to obesity gave rise to the idea of the thrifty genotype, characterizing people as genetically programmed to survive intermittent periods of hunger. "But when you put those same genes into the environment we have today," he said, the survival mechanism backfires.Researchers had hoped to find a signal that controls fat metabolism the way insulin regulates glucose metabolism. "How the loop was closed was by the discovery of a molecule called leptin," Flier said. The generation of obese mice that ate continually and had inefficient metabolisms even when on restricted diets led to the discovery of the missing leptin gene. Injecting the animals with leptin completely reversed their symptoms. Unfortunately, leptin itself is not a magic bullet: this strategy would work only in a tiny fraction of the obese human population, those with a similar mutation in the leptin gene. Instead, said Flier, "Resistance to leptin characterizes the majority of cases of obesity." Beverly Lorell, professor of medicine and director of the program in heart failure at BID, told the story of how beta blockers in the past few years have become an important treatment for congestive heart failure, when basic science argued against them. "We were taught that giving a beta blocker ... will depress function of the heart," she said, because it works against the beta-adrenergic receptors that promote tonic action in the heart. In fact, transgenic mouse models showed that overexpression of beta receptors yields very robust "super" mice. "Basic science concluded that this should be recruited for heart failure," she said. But clinical evidence proved that blocking the receptors was effective in heart patients, and Lorell said that the story highlights the importance of active cross-talk between bench scientists and clinicians. "We don't yet understand why beta blockers are so extraordinarily effective at treating heart failure," she said. They are the only class of drugs that not only boost survival rates, but can actually reverse the disease's progress in large numbers of patients. "In no area in cardiology has there been truly such a revolution," said Lorell. Aside from new treatments and discoveries about biology, the way medical students are able to examine their patients has changed a great deal. Darrell Smith demonstrated that medical imaging is not about staring at x-rays anymore and gave the audience a glimpse of the technology that has changed how breast cancer is detected and treated through ultrasound, digital mammography, PET scanning, and MRI of breast tissue. David Cardozo, lecturer in neurobiology and course director of Human Nervous System and Behavior, explained that neuroimaging techniques like functional MRI have made it possible to bring neurobiology and cognitive science together by addressing questions of consciousness at an anatomical level. The rapid rate of new discoveries in the field "changes our course every year as we get more and more knowledge," Cardozo said. —Courtney Humphries |
