Mayo Clinic Reports Findings from Research on Digestive Diseases

Monday, May 21, 2007

ROCHESTER, Minn. — Mayo Clinic physicians are sharing the findings of more than 100 studies at Digestive Disease Week 2007 in Washington, D.C., on May 20-24, including new research on irritable bowel syndrome (IBS) and dyspepsia.

IBS is a functional bowel disorder that affects nearly one in five American adults and accounts for more than one of every 10 doctor visits. It is characterized by abdominal pain or cramping and changes in bowel function, including bloating, gas, diarrhea and constipation.

Functional dyspepsia refers to unexplained chronic or recurrent pain or discomfort in the upper abdomen that is not caused by other conditions such as ulcers, cancer, gastroesophageal reflux disease (GERD) or esophagitis. Symptoms of dyspepsia include heartburn, nausea, pain or general discomfort. It is estimated 20 percent of Americans suffer from dyspepsia.

Each year, physicians at Mayo Clinic's campuses in Arizona, Florida and Minnesota treat thousands of patients who have IBS, dyspepsia and other digestive diseases. For more information on the treatment of digestive diseases at Mayo Clinic, visit www.mayoclinic.org/gi.

The following are brief, advance summaries of select studies.

EMBARGOED: Hold for release until Sunday May 20, at 10 a.m. CST

Irritable bowel syndrome aggregates strongly in families

Mayo Clinic researchers studied gastrointestinal symptom data from nearly 1,000 patients (573 with IBS, 401 healthy volunteers) and more than 1,800 first-degree relatives in order to evaluate genetic and environmental contributors to IBS. Findings showed that IBS aggregates strongly in families, and when compared to the general population, IBS risk is greater for first-degree relatives in families with at least one affected individual. Further studies are warranted to distinguish the genetic and environmental contributors to IBS.

"This study adds to the growing evidence that there's a genetic cause for IBS," says Yuri Saito, M.D., a Mayo Clinic gastroenterologist and the study's lead investigator. "With further studies, our goal is to identify a molecular base of the abnormality in order to develop more definitive treatment programs for patients with IBS."

EMBARGOED: Hold for release until Monday, May 21, at 10:30 a.m. CST

Alterations in intestinal serotonin in irritable bowel syndrome and dyspepsia

Serotonin is a neurotransmitter that helps regulate intestinal functions. Mayo Clinic researchers set out to determine the role of serotonin in patients with IBS and dyspepsia. The study involved 48 females — including individuals with IBS, individuals with dyspepsia, individuals with both IBS and dyspepsia, and healthy volunteers. Biopsies were obtained from the stomach and intestines of each patient and serotonin levels were measured. Researchers found that patients with dyspepsia had low levels of a serotonin reuptake transporter in their stomachs and high levels of a molecule that synthesizes serotonin in the small intestine.

"The results support the concept that functional disorders may be associated with altered serotonin signaling in different regions of the gut. If the data can be validated, it suggests it may someday be possible to make a diagnosis of functional disease by taking a biopsy," says Amy Foxx-Orenstein, D.O., a Mayo Clinic gastroenterologist and lead author of this study. "Mucosal markers for functional disorders might lead to earlier diagnosis and treatment, but further studies are needed."

EMBARGOED: Hold for release until Monday, May 21, at 1:15 p.m. CST

Duodenal eosinophilia may cause symptoms of dyspepsia

Eosinophils are inflammatory white blood cells that invade tissue and cause a wide spectrum of symptoms. For example, high numbers of eosinophils are commonly found during allergic reactions. Mayo Clinic researchers set out to determine whether eosinophils in the duodenum (upper small intestine) may be responsible for the symptoms of dyspepsia or irritable bowel syndrome.

The study included upper endoscopy and duodenal biopsy results from a population sample of 1,000 people, including individuals with dyspepsia, individuals with IBS, and healthy volunteers. Researchers discovered a clear-cut increase in eosinophils in the duodenal biopsies of individuals with dyspepsia. Both the individuals with IBS and the healthy volunteers had moderately lower eosinophil counts.

"This research suggests that duodenal eosinophilia may be important in causing the symptoms of dyspepsia," says Nicholas Talley, M.D., a Mayo Clinic gastroenterologist and lead author of this study. "After further research, we hope to identify the cause for increased eosinophils, which could eventually result in new diagnostic tests, new approaches to therapy and potentially, a cure for dyspepsia."
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