Our Team

​Our team has vast experience in diagnosis, management and/or treatment of digestive disorders and diseases, from heartburn to some types of cancer. They are passionate about gastrointestinal screenings which can lead to early dedication and treatment of colorectal, esophageal and liver cancer.

Harry MatossianHarry B. Matossian, MD, Gastroenterologist

Dr. Matossian is board-certified in internal medicine and gastroenterology. He has been caring for Lake and Mendocino counties for 27 years providing exemplary patient care. He earned his medical degree from Pennsylvania State University College of Medicine in State College, Pennsylvania and went on to complete a fellowship in gastroenterology at the University of Maryland Medical Center in Baltimore, Maryland.


Donald HermensDonald J. Hermens, MD, Gastroenterologist

Dr. Hermens is board-certified in internal medicine and gastroenterology with over 30 years of experience. He earned his medical degree at Creighton University Medical School in Omaha, Nebraska and went on to complete a fellowship in gastroenterology at Kansas University Medical Center, Kansas City, Kansas. He is also an active member of the American Gastroenterological Association.


Renee VinyardRenee Vinyard, PA-C

Renee Vinyard is a certified physician assistant. She is a graduate of George Washington University in Washington D.C. where she completed the physician assistant program and earned her bachelor of science degree. Renee specializes in gastroenterological diseases with an emphasis on hepatitis C and digestive disorders. She enjoys working with patients on their journey toward better health.