Research Programs

Michael D. Sitrin, MD . Dr. Sitrin’s laboratory research is focused primarily on the effects of vitamin D on intestinal function. He is studying the influence of vitamin D on cell cycle regulation, apoptosis, and colonic carcinogenesis. His laboratory has also been a leader in defining the rapid actions of vitamin D on cell signaling systems. He is also studying the molecular regulation of uncoupling protein 1 gene expression in brown adipocyte tissue, examining alterations in enterocyte cycle regulation in an experimental model of the short bowel syndrome, and is developing a novel transgenic mouse model of non-alcoholic fatty liver disease.
Dr. Sitrin is also involved with Dr. Lackner is developing new ambulant capsule technology for measurement of pH and pressure in the gastrointestinal tract. Current clinical studies are measuring gastric emptying, gastric and small intestinal motility patterns, and whole gut transit time in normal controls and in patients with gastroparesis. Another clinical project is examining strategies for optimizing colon cancer screening in the veteran population.

Michael E. Duffey, PhD. In the liver, collecting ducts transport bile and secrete an HCO 3 --rich fluid. Vasoactive intestinal peptide (VIP) is key stimulus for this secretion because it regulates basolateral membrane K + channels in duct epithelial cells (cholangiocytes) that control membrane potential driving force. Dr. Duffey hypothesizes that VIP activates a K + channel formed by co-assembly of the K + channel, KCNQ1 (KvLQT1), and the ancillary protein subunit KCNE3. His laboratory is using molecular biological and electrophysiological techniques to determine the sites of interaction of KCNE3 with the KCNQ1, and how VIP-induced phosphorylation regulates the channel. Understanding these processes is essential for the development of treatments of hepatic transport disorders in cystic fibrosis, primary sclerosing cholangitis, and cirrhosis.

Jeffrey Lackner, PhD . Dr. Lackner’s primary research interests are focused on understanding the nature and treatment of functional GI disorders, particularly irritable bowel syndrome. He is particularly interested in how the beliefs patients with IBS hold about themselves, their illness, and the future influence brain-gut interactions and explain health outcomes. This research interest is currently explored in the context of two NIH funded clinical trials of behavioral treatments designed to teach severely affected patients self-management skills for controlling symptoms severity. He is also interested in the neurophysiologic underpinnings of cognitive and affective processes and how these processes can be modified to "rewire" brain circuitry underlying IBS symptoms. This research has been addressed through a prospective PET/visceral distension study of patients undergoing a brief self management treatment. A third major research area is developing and assessing evidence-based treatments.

Thomas Mahl, MD . Dr. Mahl conducts clinical research in Hepatology. He is currently studying whether chronic hepatitis C infection pre-disposes individuals to stain-induced hepatotoxicity. He is also collaborating with researchers in Pediatric Gastroenterology and Pulmonology to examine the efficacy of a new type of pancreatic enzyme supplement in young adults with cystic fibrosis.

Shahid Mehboob , MD . Dr. Mehboob is studying whether octreotide can cause regression of gastric carcinoid tumors in a patient with chronic atrophic gastritis.

Abha Rani, MD . Dr. Rani is collaborating with investigators at the Roswell Park Cancer Institute to examine alterations in epidermal growth factor signaling in Barrett’s esophagus.