Frank Chen, MD

Surveillance in Young-Onset Colorectal Cancer
Fellow: Frank Chen, MD
Mentor/PI: Folasade P. May, MD, PhD, MPhil

Colorectal cancer (CRC) incidence in adults under 50 years of age is increasing in the United States despite an overall decline in CRC incidence in the general population. The underlying factors for this trend are unknown. The goal of surveillance colonoscopy after resection of CRC is the prevention of another primary CRC. Currently, surveillance guidelines after surgical resection for CRC do not take into account age at time of diagnosis. We seek to conduct a study that will compare surveillance outcomes in patients with young-onset CRC to traditional-onset CRC. We hope that our results will contribute to the existing literature and ultimately inform targeted guidelines specific to the care of patients with young-onset CRC.   

Lizhou Huang, MD

Machine Learning Applications in Gastrointestinal Motility Studies: High Resolution Esophageal Manometry
Fellow: Lizhou Huang, MD
Mentors/PI: Peter Chang, MD; Jeffrey L. Conklin, MD

High-resolution esophageal manometry with pressure topography (HRM) is the gold-standard in the diagnosis of esophageal motility disorders and directly affects downstream clinical decisions. Due to low volume of training and unfamiliarity, quality and consistency of HRM interpretation by non-experts is thought to be low. A convolutional neural network (CNN) is a deep learning methodology often used in the classification of biomedical images and may be beneficial in the interpretation of HRM. Our study aims to develop and train a CNN using HRM data labeled by leading experts. We hope that the resulting neural network can be applied in practice by serving as an interpretive aid to clinicians. Furthermore, a successful neural network can be used as the basis for other applications within gastrointestinal motility including impedance measurements, impedance planimetry, and anorectal manometry.

Benjamin Nulsen, MD

Use of Central Neuromodulators in Irritable Bowel Syndrome: A National Survey of Gastroenterologists
Fellow: Benjamin Nulsen, MD
Mentor/PI: Lin Chang, MD

Central neuromodulators (e.g., tricyclic antidepressants [TCA] and serotonergic agents, SSRI, SNRI) are effective in the treatment of patients with irritable bowel syndrome (IBS). However, little is known about gastroenterologists' use of these medications. This national survey, written in collaboration with Doug Drossman, MD from the Rome Foundation, will seek to describe gastroenterologists' practice patterns, attitudes and knowledge about the use of central neuromodulators in patients with IBS.

Benjamin Nulsen, MD

Studies of Dieulafoy’s Lesion as a Cause of Severe GI Hemorrhage: Risk Factors, Outcomes and Comparison with Peptic Ulcer Bleeding
Fellow: Benjamin Nulsen, MD
Mentor/PI: Dennis Jensen, MD

Dieulafoy's lesion (DL) is an important and under recognized cause of severe upper gastrointestinal hemorrhage. There is currently no consensus regarding the preferred endoscopic approach to bleeding from DL. Arterial blood flow monitoring with the doppler endoscopic probe (DEP) has emerged as an important adjunct to endoscopic hemostasis of severe GI bleeding for non-variceal upper GI lesions. In this project, we will compare 30 day outcomes between standard endoscopic hemostasis techniques and DEP-assisted treatment. We will also use multivariable analysis to develop a prediction tool for DL in patients with severe non-variceal upper GI hemorrhage.

Ryan Perumpail, MD

Safety and Efficacy of Tenofovir Alafenamide for Hepatitis B Prophylaxis Post-Liver Transplantation
Fellow: Ryan Perumpail, MD
Mentor/PI: Steven-Huy B. Han, MD

Chronic hepatitis B virus (HBV) accounts for between 5 to 10% of the liver transplantations (LT) performed at most US transplant centers. Historically, reinfection of the liver graft with HBV after LT was associated with increased risk of graft failure and poor survival. The strategy of using antiviral drugs has become the mainstay of HBV prophylaxis with prevention of graft infection achieved in most LT recipients with long-term use. Tenofovir disoproxil fumarate (TDF) is the most studied drug post-transplantation, but tenofovir alafenamide (TAF) is a relative newcomer that is likely to be favored going forward due to its superior renal and bone safety profile. While the efficacy and safety of TAF in chronic HBV was established based on registration trials, post-LT patients requiring HBV antiviral therapy were excluded. This patient population requires lifelong immunosuppression, often including calcineurin inhibitors, which are known nephrotoxins. Our study would evaluate the impact of TAF on renal function and bone mineral density compared to existing HBV antiviral therapy for HBV prophylaxis in the post-LT population based on real-world data from three centers (University of California at Los Angeles, Cedars-Sinai Medical Center, and Keck Hospital of University of Southern California). As this study would represent the largest clinical experience in this group, it may influence clinical practice patterns at liver transplantation centers worldwide. If the purported renal and bone toxicity benefits of TAF are validated in this real world study, TAF may become the standard of care for HBV prophylaxis post-LT.