Research

Michael D. Sitrin, M.D. Dr. Sitrin's research is focused on malabsorption and nutritional and metabolic aspects of digestive diseases. He studies the role of Vitamin D deficiency in gastrointestinal disorders such as inflammatory bowel disease and colorectal cancer. He also collaborates with Dr. Jeffrey Lackner on studies focused on better understanding the pathogenesis and treatment of irritable bowel syndrome. Dr. Sitrin is working with the Division of Endocrinology to examine the effects of different diets on intestinal permeability to endotoxin and inflammatory markers in patients with cirrhosis.

Michael E. Duffey, Ph.D. 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, PsyD. 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, M.D. 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.

Abha Rani, M.D. Dr. Rani's research interests are in women's health and studies looking at the quality assurance in clinical practice. She is currently looking at parameters of quality assurance in upper endoscopy done for GI bleed.

Jeanette Keith, MD. Dr. Keith's research is focused on the GI and nutritional implications of bariatric surgery. She also studies calcium and Vitamin D metabolism, lactose maldigestion, as well as issues related to women's and minority health.