Clinical Focus

  • Esophageal Dysphagia
  • Gastroenterology

Academic Appointments

Administrative Appointments

  • Director, GI Motility and Neurogastroenterology, Division of Gastroenterology (2008 - Present)

Professional Education

  • Fellowship:California Pacific Medical Center (2005) CA
  • Board Certification: Gastroenterology, American Board of Internal Medicine (2005)
  • Residency:California Pacific Medical Center (2002) CA
  • Medical Education:UCLA School of Medicine (1999) CA
  • MD, UCLA School of Medicine (1999)

Research & Scholarship

Current Research and Scholarly Interests

My research interests focus on disorder of gastrointestinal motility. Specifically, those related to nausea and vomiting with or without gastroparesis, reflux and swallowing disorders, and irritable bowel syndrome. My research focuses on understanding and characterizing the abnormal motility pattern(s) that are associated with these symptoms.


2013-14 Courses


Journal Articles

  • Massive gastrointestinal dilatation in a case of hereditary hollow visceral myopathy. Digestive and liver disease Huang, R. J., Yun, C., Nguyen, L. 2013; 45 (10): 866-?

    View details for DOI 10.1016/j.dld.2013.04.005

    View details for PubMedID 23816694

  • Platelet-derived growth factor receptor a (PDGFRa)-expressing "fibroblast-like cells" in diabetic and idiopathic gastroparesis of humans NEUROGASTROENTEROLOGY AND MOTILITY Grover, M., Bernard, C. E., Pasricha, P. J., Parkman, H. P., Abell, T. L., Nguyen, L. A., Snape, W., Shen, K. R., Sarr, M., Swain, J., Kendrick, M., Gibbons, S., Ordog, T., Farrugia, G. 2012; 24 (9): 844-852


    Emerging evidence suggests that "fibroblast-like cells" (FLC) may play a role in the regulation of gastrointestinal (GI) motor function. FLC are ultrastructurally distinct from other interstitial cells, including interstitial cells of Cajal (ICC), and express small-conductance Ca(2+) -activated K(+) channels (SK3). In mice, platelet-derived growth factor receptor ? (PDGFR?) antibody has also been shown to label FLC. The aims of this study were to determine the morphology and distribution of PDGFR?-immunoreactive (ir) FLC in human gastric muscle and to determine if FLC are altered in gastroparesis, where ICC are reduced.Full thickness gastric body biopsies from five healthy subjects, 10 diabetic, and 10 idiopathic gastroparesis patients were immunolabeled using SK3 and PDGFR? staining for FLC and Kit staining for ICC. Intramuscular FLC and ICC were quantified.Intramuscular PDGFR?-ir cells had slender cell bodies and long, thin processes and were more abundant in the longitudinal compared with the circular muscle. In the region of myenteric plexus, FLC had smaller, rounder cell bodies with 3-4 processes and formed networks, often around ganglia. All SK3-ir cell structures showed complete overlap with PDGFR?-ir. FLC were in close proximity to ICC, but their cell bodies did not overlap. No differences were seen in the distribution, morphology, or overall numbers of FLC in gastroparesis patients.In conclusion, PDGFR? identifies FLC in human gastric smooth muscle. FLC were not altered in distribution or overall numbers in gastroparesis. Additional studies are required to determine their role in human GI function.

    View details for DOI 10.1111/j.1365-2982.2012.01944.x

    View details for Web of Science ID 000308089000012

    View details for PubMedID 22650155

  • Gastrointestinal Dysmotility DIGESTIVE DISEASES AND SCIENCES Nimgaonkar, A., Choi, J. W., Nguyen, L., Triadafilopoulos, G. 2012; 57 (5): 1130-1133

    View details for DOI 10.1007/s10620-011-1946-x

    View details for Web of Science ID 000303385100004

    View details for PubMedID 22038542

  • Characteristics of Patients With Chronic Unexplained Nausea and Vomiting and Normal Gastric Emptying CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Pasricha, P. J., Colvin, R., Yates, K., Hasler, W. L., Abell, T. L., Uenalp-Arida, A., Nguyen, L., Farrugia, G., Koch, K. L., Parkman, H. P., Snape, W. J., Lee, L., Tonascia, J., Hamilton, F. 2011; 9 (7): 567-U89


    Chronic nausea and vomiting with normal gastric emptying is a poorly understood syndrome; we analyzed its characteristics.We collected and analyzed data from 425 patients with chronic nausea and vomiting, enrolled at 6 centers by the Gastroparesis Clinical Research Consortium in the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Registry.Among the patients, 319 (75%) had delayed emptying, defined by the results of a standardized, low-fat meal, and 106 had normal gastric emptying. Patients with or without delayed emptying did not differ in age, sex, or race, although those with normal gastric emptying were less likely to be diabetic. Symptom severity indexes were similar between groups for nausea, retching, vomiting, stomach fullness, inability to complete a meal, feeling excessively full after meals, loss of appetite, bloating, and visibly larger stomach. There were no differences in health care utilization, quality of life indexes, depression, or trait anxiety scores. However, state anxiety scores were slightly higher among patients with delayed gastric emptying. Total gastroparesis cardinal symptom index scores were not correlated with gastric retention after 2 or 4 hours in either group. Patients with the syndrome were not adequately captured by the stand-alone criteria for the Rome III diagnoses of chronic idiopathic nausea and functional vomiting. With rare exceptions, the diagnosis remained stable after a 48-week follow-up period.Patients with nausea and vomiting with normal gastric emptying represent a significant medical problem and are, for the most part, indistinguishable from those with gastroparesis. This syndrome is not categorized in the medical literature--it might be a separate clinical entity.

    View details for DOI 10.1016/j.cgh.2011.03.003

    View details for Web of Science ID 000292467900015

    View details for PubMedID 21397732

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