Our June 20th Distinguished Speakers

Melissa Hoffman, PhD

Clinical Chemistry Fellow

Center for Advanced Laboratory Medicine, Department of Pathology

University of California-San Diego

Melissa Hoffman, Ph.D. is a Clinical Chemistry Fellow mentored by Dr. Rob Fitzgerald at UC San Diego Center for Advanced Laboratory Medicine Toxicology lab. She attended the University of South Florida where she received her Ph.D. in Cancer Biology. Her graduate work was performed at the Moffitt Cancer Center under Dr. John Koomen’s mentorship, where she was trained in mass spectrometry. She applied her interdisciplinary background to her dissertation research, which focused on using quantitative proteomics to support translational cancer research with an emphasis on personalized cancer diagnostics development. In her current fellowship, she is expanding her skills in the areas of small molecule analysis and clinical method validation and in the future hopes to apply these skills to IVD development for improved disease monitoring.

Quantification of Cannabinoids in Oral Fluid, Breath, and Whole Blood to Evaluate Markers of Recent Cannabis Smoking and Driving Impairment


With legalization of recreational and medical cannabis occurring in 10 and 33 states, respectively, cannabis usage is on the rise. Increased prevalence of cannabis consumption and subsequent intoxication resulting in impaired driving has led to a growing public safety concern. With legalization comes the responsibility of developing methods to distinguish which markers correlate with recent cannabis use, but not past use, and to determine cutoff levels that correlate with driving impairment. To address this need, we have developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays to measure ∆9-tetrahydrocannabinol (THC) and 9 additional metabolites or cannabinoids in whole blood, oral fluid, and breath. These LC-MS/MS measurements are applied to a clinical study, which is funded by California assembly bill 266, evaluating the impact of smoking a cannabis joint with THC concentrations of ~0%, 6% and 13% on driving using a driving simulator. Patterns of metabolite concentrations for 5-6 hours following smoking along with sensitivity and specificity of recent cannabis smoking markers in all three matrices have been evaluated. This study is an important step in scientifically determining cutoffs to direct cannabis DUI per se laws with the long-term goal of improving road safety while minimizing persecution of non-impaired cannabis users. 

Jay Kirkwood, PhD

Academic Coordinator

Metabolomics Core Facility

Institute for Integrative Genome Biology

University of California-Riverside


Jay Kirkwod, Ph.D., received his PhD in Medicinal Chemistry from Oregon State University in 2013. The focus of his thesis was the development and broad biological application of both targeted and untargeted LC-MS based metabolomics platforms. He spent two years as a postdoctoral researcher at Colorado State University where his research focused on the development and implementation of targeted, quantitative small molecule assays using triple quadrupole mass spectrometry. Jay currently serves as the Academic Coordinator of the recently established Metabolomics Core Facility at UC Riverside.

​Using metabolomics to elucidate protein function and mechanisms of drug action

The growing field of metabolomics aims to characterize and quantify metabolites, or small molecules, on a comprehensive level. We can attribute the rise in metabolomics studies not just to recent advances in technology, but also to a growing appreciation of metabolism’s central role in health and disease. This seminar covers two metabolomics studies. In the first, metabolomics identified the substrate of a pathogenic bacterial enzyme responsible for plant infection and food crop destruction. In the second, metabolomics helped pinpoint the potential mechanisms of action of a flavonoid in hops with antiobesity properties.