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March 15, 2010

Ulcer Answers


Digesting the facts on stomach ulcers

Massachusetts resident Jay Tang can remember many restless nights. "It's excruciating pain. I would feel this burning pain in my stomach and then it would last for many hours," he recalls. "Then you try to lie down but you still feel the pain and suffer. And you can't even take pain medicine because the painkiller doesn't really help with stomach pain." Tang was suffering from a peptic ulcer--or as it's more commonly known, a stomach ulcer. Every year, nearly four million people in the United States are afflicted with the disease.

A stomach ulcer is a small erosion in the stomach lining or the first 12 inches of the gastrointestinal tract. The explanation of how you contract an ulcer has evolved from what seemed like an educated guess 50 years ago to something based more in scientific fact today.

For years, it was believed that contracting an ulcer was as much an emotional ailment as it was a physical one. Patients were told to stay away from certain foods, such as spices, that stimulate acidic production in the stomach.

Stomach ulcers came with a stigma as well. It was widely accepted that ulcers came to those who bottled up their emotions. The thinking was that the more you held in those feelings, the more your brain would send signals to your stomach to secrete acid. Too many signals from the brain to the stomach meant too much acid; enough to erode the lining of the stomach and cause a sore to develop. Calming down, avoiding spices, and taking antacids would treat the condition. Or so it was thought.

To understand the real cause of stomach ulcers like the one that caused Jay Tang's pain, you have to learn a little about the anatomy of the human stomach. The stomach is a sac, the first place your food goes after you swallow it. The stomach secrets chemicals, such as hydrochloric acid, that help sterilize food before it moves on into the rest of your digestive system. Stomach acid is nearly as strong as car battery acid. In fact, without the protective mucosal gel lining its wall, your stomach would digest itself.

When you have a stomach ulcer, there is a spot along the gel that is eroded. Without the protection of the gel, stomach acid attacks the cells of your stomach wall and a sore develops. That sore is an ulcer. And, as it turns out, what truly causes the gel to erode is not the result of spicy meals or raw nerves.

In 1982, two Australian scientists, Robin Warren and Barry Marshall, were able to link Helicobacter pylori (H. pylori) bacteria to most stomach ulcers. They eventually went on to win the 2005 Nobel Prize in Medicine for their work.

A lot has been learned about the workings of H. pylori since the discovery of its link with ulcers. For example, researchers found out how the microbe is able to survive and thrive in the harsh acidic environment of the stomach. It turns out H. pylori uses a unique chemical process that neutralizes the acidic environment around it. The bacteria secret an enzyme called urease which forms ammonia. Ammonia neutralizes acid. This chemical process is H. pylori's protective shield in an otherwise deadly environment.

For Jay Tang, suffering from an ulcer also turned out to be a cruel irony. "I'm a biophysicist by training, so I study, among other things, how bacteria infect tissues." Tang doesn't study the H. Pylori bacteria. But his friend and colleague, Dr. Rama Bansil, does. She's a biophysicist at Boston University who spent a fair amount of time studying the world of H. pylori bacteria with students and colleagues from Harvard Medical School and MIT. Bansil, along with then-graduate student Jonathan Celli, wanted to find out how H. pylori bacteria are able to bore through to the protective mucosal gel lining and wreak havoc on healthy stomach tissue.

Conventional wisdom held that the corkscrew-shaped H. pylori relied on its shape to twist and bore its way through the mucosal gel. With support from the National Science Foundation (NSF), what Bansil and Celli found was that the same chemical process the bacteria use to survive and protect themselves against the stomach acid is also used to make the acidic mucosal gel of the stomach more liquid like. Under those conditions, the bacteria are able to swim through to the stomach wall.

"Once they're in there and they're in the gel, they would otherwise be stuck. So by secreting this enzyme urease, the pH around the bacteria goes up; it goes from being acidic to neutral, and when the pH becomes neutral, the mucus is no longer a gel and that creates a condition by which the bacteria are able to swim freely," explains Celli.

Bansil adds that the work is important because "if you know the exact physiological conditions under which H. pylori attacks the stomach, then you could design drugs which counteract those conditions."

While Bansil and her colleagues plan to continue studying H. pylori infection, she points out significant questions remain about how stress relates to ulcers. "Why only some people get ulcers even though the bacterium is found in about half the world's population is still a big mystery and maybe that's where stress and other factors come in," notes Bansil.

For Jay Tang, his H. pylori-related disease is a thing of the distant past. It's been over a decade since he's suffered from a stomach ulcer. "I don't have to worry that this organ in my body will repeatedly fail me. That's really a sense of relief and I am grateful I was really cured," he says.

Miles O'Brien, Science Nation Correspondent
Jon Baime, Science Nation Producer


Any opinions, findings, conclusions or recommendations presented in this material are only those of the presenter grantee/researcher, author, or agency employee; and do not necessarily reflect the views of the National Science Foundation.