Our Team

Administrative Team

The administrative team of the Department of Orthopaedic Surgery is a vital component of the department's success. Located in the Lawrence J. Ellison Ambulatory Care Center, the team is responsible for seamlessly operating the department's programs and services, delivering unparalleled support to the faculty and staff. With diverse backgrounds and extensive experience, the team brings a wealth of skills and expertise to their roles, making them an essential part of the department's success.

Chief Administrative Officer

Joseph MacDonald, M.B.A.
jemacdonald@ucdavis.edu
916-734-8154  

Management Service Officer

Rieko Ringo
ruringo@ucdavis.edu
916-734-7103

Sharon Misewich, CRA
Research and Finance Analyst
sbmisewich@ucdavis.edu
916-734-4280

Shannon Untalasco
Academic Personnel Manager
suntalasco@ucdavis.edu
916-734-3889

Robyn Baker
Academic HR Analyst II

Administrative Staff

Mazie Grigas
Administrative Assistant to Trauma 
mjngai@ucdavis.edu
916-734-2182

Rebecca Misner
Administrative Assistant to Foot/Ankle and Sports Medicine Services
rjmisner@ucdavis.edu
916-734-5874

Nicole Nisson
Administrative Assistant to Hand and Pediatrics Services
nsnisson@ucdavis.edu
916-734-3678

Debra Sample
Executive Analyst to the Department Chair
dasample@ucdavis.edu
916-734-7353

Michelle Ramirez 
Administrative Assistant to Adult Reconstruction and Pediatrics
manramirez@ucdavis.edu

Madeline Snoke
Front Desk/Research Administrative Assistant
mfsnoke@ucdavis.edu
916-734-3885

Venessa With 
Administrative Assistant to Spine Service and Oncology
vwith@ucdavis.edu
916-734-2937

Margaret MacNitt
Education Programs Manager
mlmacnitt@ucdavis.edu
916-734-2807

Delia Luna
Fellowship Coordinator 
dbluna@ucdavis.edu 

Research Staff

Chancey Sweeney, Ph.D., M.P.A., M.H.A.
Clinical Research Supervisor 2
cassweeney@ucdavis.edu
916-734-6017

Marisa Arnold
Clinical Research Coordinator
mesalvador@ucdavis.edu 
916-734-6935

Andrew Buck
Clinical Research Coordinator
ajbuck@ucdavis.edu

Leslie Mellor, CCRC
Sr. Clinical Research Coordinator
ljmellor@ucdavis.edu  

Julia Martin, CCRC
Sr. Clinical Research Coordinator
jyhmartin@ucdavis.edu
916-734-8175

Maya Porter, B.S., CCRP
Sr. Clinical Research Coordinator
mtporter@ucdavis.edu
916-734-4216

Oak Park Research Lab

Naymalis La Santa
Lab Manager 
nlasanta@ucdavis.edu

Marketing and Communications  

Sonia Kumar
Communications Specialist III
sekumar@ucdavis.edu