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Minneapolis VA Health Care System Research Service


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Leadership Team

Hanna Bloomfield

Hanna E. Bloomfield, MD, MPH

Associate Chief of Staff for Research

612-467-2800 |

A graduate of Harvard College and Boston University Schools of Medicine and Public Health, Dr. Bloomfield is a board-certified general internist, Professor of Medicine at the University of Minnesota, and Associate Chief of Staff for Research at the Minneapolis VA Health Care System. Dr. Bloomfield conducts clinical, epidemiologic, and health services research with an emphasis on chronic conditions common in older Veterans. She was the founding Director of and now serves as Senior Investigator at the Center for Care Delivery and Outcomes Research (CCDOR), a federally funded Health Services Research Center of Excellence. Dr. Bloomfield has published over 100 papers and presented research findings at multiple national and international scientific meetings. She is featured on the Wall of Scholars at the University of Minnesota Medical School for her publication in the New England Journal of Medicine which has been cited over 2000 times.

Joshua Nixon

Joshua P. Nixon, PhD

Deputy Associate Chief of Staff for Research

612-467-2804 |

Dr. Nixon has a longstanding research interest in neural mechanisms driving behavior and how environmental triggers influence these brain systems. His work focuses on pre-clinical models. He has a broad background in behavioral neuroscience, with specific experience and training in circadian biology, obesity and ingestive behavior, neuroprotection, and neurodegenerative disease. He serves as Chair of the facility Subcommittee on Research Safety, and leads the Research Information Protection & Security working group. Dr. Nixon is an Assistant Professor in the University of Minnesota Department of Surgery, an Adjunct Assistant Professor in the University of Minnesota Department of Food Science and Nutrition, and a graduate of Michigan State University (BS, PhD).

10 year VA service pin

Matthew Rassette, DVM

Veterinary Medical Officer; Chair, Research & Development Committee

612-467-4585 |

Dr. Rassette is one of two Veterinary Medical Officers for the MVAHCS Research program, and also serves on the Subcommittee on Research Safety, the Institutional Biosafety Committee, the Institutional Animal Care and Use Committee, and was appointed as Chair of the Research and Development Committee in 2019. He is a Certified Professional IACUC Administrator (CPIA) and was admitted as a Diplomate into the American College of Laboratory Animal Medicine. Dr. Rassette is a graduate of Georgetown University (BS) and the University of Wisconsin School of Veterinary Medicine (DVM).

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Andrew Mass, MBA

Administrative Officer

612-467-2814 |

Mr. Mass served as the Budget Analyst for the Minneapolis VA Research program since returning from deployment in late 2010. He began serving as Administrative Officer in the summer of 2020. He loves working with numbers and creating tools that give investigators a more empowered look at their studies. Mr. Mass completed his undergraduate work at Michigan State University and earned his MBA at Purdue University.

15 year VA service pin

Julie Toth, RN, CCRC, CIP

Director, Human Research Protection Program

612-467-5655 |

Ms. Toth served as the Administrator of the Minneapolis VA Health Care System IRB beginning in 2011, recently expanding the scope of her work to direct the MVAHCS Human Research Protection Program. She worked many years as a research study coordinator/research nurse, most recently in heart failure research at MVAHCS. She brings the researcher perspective to her work guiding investigators through the regulatory process, and enjoys discussing new projects, as well as challenges in existing projects, with the investigative teams.