Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States of America.|UCSF/UCB Joint Graduate Group in Bioengineering, University of California, Berkeley, Berkeley, CA, United States of America.|Tempus Dictum, Inc., Milwaukie, OR, United States of America.|Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States of America.|Division of Gastrointestinal and Liver Diseases, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States of America.|Division of Gastrointestinal and Liver Diseases, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States of America.|Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States of America.