Board of Directors

Dr. Obrinsky has been practicing Pediatrics in the Tri-Valley community since 1989.  He attended the School of Public Health at the University of California, Berkeley and obtained a M.S. in Epidemiology in 1982. He then attended medical school at Hahnemann University in Philadelphia and did his residency at Children’s Hospital Oakland.  He is board certified by both the American Board of Pediatrics and the National Board of Physicians and Surgeons.  Upon completing his residency in 1989 he joined San Ramon Valley Primary Care.  Dr. Obrinsky joined the John Muir Medical Group in 2016 when SRVPC was acquired by John Muir Health.  In 2018, Dr. Obrinsky was elected to the Board of Directors for John Muir Medical Group.

Dr. Obrinsky is married and with his wife Kristen has raised 3 sons.  He enjoys playing golf, cooking, traveling, and spending time with family and friends.

Karen L. Sonnenthal has been with John Muir Medical Group since 1997, joining the group after graduating with a Masters in Nursing Science from Oregon Health Sciences University.  

Born in California, Karen grew up in Baltimore Maryland, then moved to Oregon where she attended the University of Oregon and received an undergraduate degree in Biology and Psychology. 

Karen is currently working as a Family Nurse Practitioner, and is the Associate Medical Director for the NP/PA group within John Muir Medical Group.  She is also a member of the Quality and Compensation Committees.

Outside of work she enjoys hiking, gardening and reading as well as spending time with her boys—husband Eric, son Nate, and 2 fur pups Luca and Max.

Dr. Johnson Adeyanju graduated with honors in Bachelor of Science from the University of New Orleans, received Doctor of Medicine degree from Louisiana State University School of Medicine in New Orleans, Internship at the Los Angeles Community Hospital-USC School of Medicine, and completed Residency training in Internal Medicine at the University of California Davis VA Medical Center.

Dr. Adeyanju is board certified in Internal Medicine and A Fellow of the American College of Physicians.

Dr. Adeyanju served as the former Treasurer, President-Elect and The President of the Association of Nigerian Physicians in the Americas (ANPA). He’s a current member of ANPA Board of Directors and Executive council and is the Author of Deadly Revenge (Shadow of the Enemy), a mystery novel about Lagos, Nigeria.

Dr. Adeyanju is a founding member of John Muir Medical Group. He has served on JMMG quality committee, currently on the Governance committee and is the Physician Site Lead for JMMG Concord Urgent Care.  He currently presides as the Co-Chair of Continuing Medical Education for physicians for John Muir Health.

Kishore Nath, MD has been with John Muir Medical Group since October 2009 practicing Family Medicine. As the Medical Director of John Muir Health’s free mobile health clinic since 2010, Dr. Nath has actively pursued his passion for providing care to the vulnerable and underserved.  In 2016 he joined the John Muir Health Family Medicine Residency Program, as their first Core Faculty member. Helping develop and implement the John Muir Health Residency program has been a fruitful experience combining his love of teaching and research with high quality patient care.

Dr. Nath is an assistant professor of Family and Community Medicine with UCSF.  He is also a Clinical Adjunct Professor of Family Medicine at USC’s Keck School of Medicine, and Adjunct Assistant Professor with Touro University.

Dr. Nath received his undergraduate education at the University of California, Berkeley then returned home to attend medical school at the University of Southern California, Keck School of Medicine and completed his Internship and Residency at Long Beach Memorial Medical Center.  He served as Chief Resident from 2000-2001 and received the resident teacher award in 2001 upon graduation from the Society of Teachers in Family Medicine. He is a graduate of the University of California, San Francisco Faculty Development Fellowship as well.  Dr. Nath is board certified in Family Medicine.

Born and raised in Southern California, he remains a devoted Dodgers and Lakers fan.  He enjoys watching his kids grow and tries to return to the beach whenever he can.  Dr. Nath is currently working on a project to bring supplies and evidence based training to a medical clinic on the outskirts of Arequipa, Perú. Service to patients at home and abroad is invigorating for Dr. Nath and teaching the next generation of physicians to serve with humility and enthusiasm is his small contribution to the John Muir Health community.

Robin Meezan was born and raised in Napa Valley.  She went to college at Stanford University where she received a BA in Human Biology.  Dr Meezan attended the University of Alabama School of Medicine for her MD and completed her pediatric residency at UCSF Benioff Children's Hospital Oakland.   In 2006 she started as a pediatrician in Berkeley, and in 2013 she became a partner with John Muir Medical Group moving her practice to Orinda.  Robin Meezan lives with her husband and two children in Orinda, she enjoys making pottery, cooking projects, tending to her fruit trees, and hiking all around the Bay Area.  

Dr Meezan enjoys building relationships with parents caring for infants all the way through the teenage years.  She has a special interest in helping with sleep and nutrition at all ages.  She is the Medical Director for Pediatrics and the Medical Student Liaison for John Muir Medical Group.