Clinical Focus

  • Pediatric Gastroenterology

Academic Appointments

Professional Education

  • Residency:UCLA Medical Center Internal Medicine (2013) CA
  • Fellowship:Stanford Hospital and Clinics (2016) CA
  • Board Certification: Pediatrics, American Board of Pediatrics (2013)
  • Medical Education:University of California Irvine School of Medicine (2010)


All Publications

  • Mass cytometry reveals a distinct immunoprofile of operational tolerance in pediatric liver transplantation. Pediatric transplantation Lau, A. H., Vitalone, M. J., Haas, K., Shawler, T., Esquivel, C. O., Berquist, W. E., Martinez, O. M., Castillo, R. O., Krams, S. M. 2016


    Long-term IS in transplant patients has significant morbidity, poorer quality of life, and substantial economic costs. TOL, defined as graft acceptance without functional impairment in the absence of IS, has been achieved in some pediatric LT recipients. Using mass cytometry, peripheral blood immunotyping was performed to characterize differences between tolerant patients and patients who are stable on single-agent IS. Single-cell mass cytometry was performed using blood samples from a single-center pediatric LT population of operationally tolerant patients to comprehensively characterize the immune cell populations in the tolerant state compared with patients on chronic low-dose IS. Specific T-cell populations of interest were confirmed by flow cytometry. This high-dimensional phenotypic analysis revealed distinct immunoprofiles between transplant populations as well as a CD4(+) TOT (CD4(+) CD5(+) CD25(+) CD38(-/lo) CD45RA) that correlates with tolerance in pediatric LT recipients. In TOL patients, the TOT was significantly increased as compared to patients stable on low levels of IS. This TOT cell was confirmed by flow cytometry and is distinct from classic Treg cells. These results demonstrate the power of mass cytometry to discover significant immune cell signatures that have diagnostic potential.

    View details for DOI 10.1111/petr.12795

    View details for PubMedID 27781378

  • Role of imaging in the evaluation of inflammatory bowel disease: How much is too much? World journal of radiology Haas, K., Rubesova, E., Bass, D. 2016; 8 (2): 124-131


    Inflammatory bowel disease (IBD) is a lifelong condition with waxing and waning disease course that requires reassessment of disease status as well as screening for complications throughout a patient's lifetime. Laboratory testing, endoscopic assessment, and fecal biomarkers are often used in the initial diagnosis and ongoing monitoring of a patient with IBD. Imaging plays an integral role in the diagnosis and evaluation of IBD. Different imaging modalities can be used over the course of a patient's lifetime, from the initial screening and diagnosis of IBD, to determining the extent of intestinal involvement, monitoring for disease activity, and evaluating for complications of uncontrolled IBD. The various imaging modalities available to the provider each have a unique set of risks and benefits when considering cost, radiation exposure, need for anesthesia, and image quality. In this article we review the imaging techniques available for the evaluation of IBD including fluoroscopic small bowel follow-through, computed tomography enterography, magnetic resonance enterography, and transabdominal ultrasound with particular focus on the judicious use of imaging and the risks and benefits of each option. We also review the risks of ionizing radiation, strategies to reduce exposure to ionizing radiation, and current imaging guidelines among pediatric and adult patient with IBD.

    View details for DOI 10.4329/wjr.v8.i2.124

    View details for PubMedID 26981221

  • Adenovirus Hepatic Abscess: A Novel Source of Fever of Unknown Origin in a Pediatric Liver Transplant Recipient. Digestive diseases and sciences Haas, K., Longacre, T., Castillo, R. O. 2016: -?

    View details for PubMedID 26856716

  • Intractable Diarrhea in Two Brothers: Late Diagnosis of Tufting Enteropathy in Adolescence DIGESTIVE DISEASES AND SCIENCES Haas, K., Martin, B., Martin, M., Kerner, J. 2016; 61 (2): 381-383

    View details for DOI 10.1007/s10620-015-3766-x

    View details for Web of Science ID 000369012100012

    View details for PubMedID 26115750

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