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COURTESY J. OCHOAJuan Ochoa started his doctoringcareer as a general practitioner with abent toward preventative medicine inthe 1980s. That was in the 8,000-foot-high mountain town of Santa Barbara,Colombia, a few hours’ drive from Medellín,where he’d spent his formative years. He evenhad a weekend radio show, “The Doctor atYour Home.” But Ochoa was fresh out ofmedical school, a bit naive, he says, and lesseffective than he expected to be. He wouldencourage women to breast-feed, for example,not realizing that practice was stigmatized inthe rural area. Even the doctor on the radiowasn’t going to change people’s minds.“I went there naively thinking I was goingto be a missionary. And I left thinking, ‘This isfar more complex than I ever thought.’”Ochoa decided to specialize. Today, as atrauma surgeon and basic scientist, he is still acreature of prevention.The questions the University of Pittsburghprofessor of surgery and critical care medicinepursues now to save and improve lives are notso much about how to get people to changetheir behaviors, but how to convincecells to do so.Since he first came to Pitt forclinical and research training in 1991,Ochoa has wondered: What do you feed traumapatients? Especially those who can’t feedthemselves? Many surgeons wait a few daysafter surgery, until the bowels are functioningagain, before feeding. Ochoa believed thatthe right diet, given earlier, would strengthenpatients, helping them survive and stave offinfection.Studies have since suggested Ochoa wasright. But feeding trauma patients is not asimple matter of inserting a tube and turningon a few monitors. The science behind nutritionafter trauma is at least as complex as thesocial taboos of Santa Barbara. Our bodiesare sometimes better able to cope with a littlestarvation than force-feeding, notes Ochoa.Trauma patients, in particular, are highly susceptibleto infection. More than 50 percentwith severe injuries are likely to end up withinfections. And feeding someone the wrongformula can actually make it more likely thepatient ends up on the unfortunate end ofthose statistics.“For some reason, the injury process createsa state of immune suppression,” Ochoa says.Many surgeons began using what’s called an“immune-enhancing” diet for surgical patientsdeveloped several years ago. That was on theheels of medical science’s realization that nitricoxide, the toxic gas your car coughs out ofits exhaust pipe, is also manufactured by ourbodies as part of the immune response. Thediet includes, among other things, the aminoacid arginine, a precursor to nitric oxide.Ochoa believes the diet is probably appropriatefor trauma patients and has tested safefor most other surgical patients. But surgeonsaren’t in agreement about that. There’s noprotocol in the United States—use of the dietdiffers from doctor to doctor and case to case.(The European society concerned with nutritionamong surgical patients recommendsusing such diets before elective surgery.)Now Ochoa believes that doctors are onthe cusp of understanding how an argininediet works and why it may be helpful for somepatients and not others. His family ties havehelped him make sense of the science.His brother, Augusto Ochoa, is interimdirector of Louisiana State University’s StanleyS. Scott Cancer Center. When Augusto Ochoawas a researcher at the National CancerInstitute in the ’90s, he began to answer aquestion that perplexed many cancer researchers:Why don’t our immune systems put up abetter fight against cancer cells?“For many years,” Juan Ochoa explains,“doctors have been trying to boost the immunesystem to make it reject the tumor. But in agood number of patients, those lymphocytesthat have been recruited to get rid of thetumor just don’t seem to work.”In the early ’90s, cancer researchers, notablyAugusto Ochoa, recognized that a peptidecalled the “zeta chain” was missing in lymphocytes(specifically T cells) of cancer patients.“People didn’t know why it was lost, butthey knew it was important,” says Juan Ochoa.T cells play a vital role in defending cells fromviruses, foreign tissue, and other unwelcomeguests.Years later, in 2001, the Ochoa brothersbegan publishing reports showing that argininewas essential to maintaining the zetachain. Around the same time, a Japanesescientist showed that trauma patients weremissing the zeta chain.What do you feed trauma patients who can’t feed themselves?Juan Ochoa had learned from his owninvestigations that arginase, an enzyme thatmetabolizes arginine, is present at elevatedlevels in the tissue of trauma patients. Patientswith more arginase don’t do well. If they survive,they are sicker and stay in the hospitallonger. The high levels of arginase somehowinhibit the ability of the injured body to keepthe needed arginine in store.The Ochoa brothers began exploringwhether the immune system is dampenedthe same way in cancer patients. They foundthat arginase is elevated in the tissue of cancerpatients, much like it is in trauma patients.The brothers also learned what arginase wasup to: At the heart of the immune response, itrobs the arginine necessary to build the zetachain. That leaves the T cell unable to proliferateto help fight off intruders and leaves thepatient unprotected.Augusto Ochoa and collaborators havesince injected arginine into the tumor of amouse. That therapy stopped the tumor fromgrowing further.Juan Ochoa believes that immune-enhancingdiets work similarly: A high concentrationof arginine restores the zeta chain, allowing theT cell to do its job to fight off infection.“It’s not proven. But we’re closing the loopon that,” he says.He’s anxious to start refining a diet forprecommercial testing in trauma patients.(Arginine, for example, doesn’t taste great andcan have adverse effects. Juan Ochoa is lookingtoward substituting it with citrulline, amore palatable amino acid found abundantlyin watermelon. Citrulline works the same wayand seems to be safer.) “Now that we knowthe mechanism, we can make better diets,”he says.He’s optimistic about the possibilities: “Soif we could block the [process that cuts out thezeta chain], we could potentially have a treatmentfor cancer. We could also have a potentialtreatment for infection in trauma.”He suspects that the immune system isdampened the same way in leprosy and tuberculosisand wonders whether those diseasescould be managed through diet as well. ■Jessica Mesman contributed to this article.SUMMER 2007 9