Our Team

Derek Nagle, MD, FACS

Dr. Nagle received his Bachelor of Science as well as his Medical Doctorate from North Dakota State University. Following his medical education, he completed his residency training with the Grand Rapids Medical Education and Research Center through Michigan State University (MSU), where he is now a member of the faculty. He is also a member of the American College of Surgeons and American Society for Metabolic and Bariatric Surgery.

Dr. Nagle is married with two children. He is an avid outdoorsman and enjoys hunting, running, scuba diving, skiing and many other hobbies. He is a commercial pilot and donates time to Wings of Mercy, which provides free air transportation to patients who need treatment at distant medical facilities.

Erica Griffin, MD

Dr. Griffin is a board-certified family and obesity medicine physician with specialized experience in non-surgical bariatric medicine. She earned a Bachelor of Science in Biochemistry from Northern Michigan University before earning her Doctor of Medicine from the Michigan State University College of Human Medicine. She then went on to complete her residency in family medicine with Racine Family Practice, which is affiliated with the Medical College of Wisconsin Racine. Dr. Griffin also completed a fellowship in obesity medicine.

Prior to joining UP Health System, she was a practicing physician with the United States Air Force, based in Colorado, Germany and Japan. She also works with the DJ Jacobetti Home for Veterans in Marquette.

“I have lived all over the world, and the Upper Peninsula is the best place to live. My job gives me the opportunity to be invited into people’s lives—people that I would never get to interact with and help unless I was a doctor. I’m so grateful for that.”

Outside of work, Dr. Griffin enjoys cross-country skiing, hiking, gardening, reading, quilting, and spending time with her family, including her twin daughters.

Michelle Lexmond, PA-C, MPH

Michelle Lexmond is a certified physician assistant who has specialized in pre- and post-bariatric surgery care, as well as non-surgical medical weight loss, with UP Health System – Marquette since 2007. She received her Bachelor of Science in Physiology from San Francisco State University before furthering her education at Northeastern University in Boston, Massachusetts, where she received her Master of Health Professions in the Physician Assistant Program.

Following her formal education, Michelle gained experience in the areas of primary care, surgery (general, orthopedic and plastic), internal medicine, gynecology and urgent/emergent care before settling into her current role.

“I’m committed to treating my patients and coworkers with respect and integrity. It is incredibly inspiring to witness the transformation of our patients who regain their health and wellness after weight loss.”

Outside of work, Michelle enjoys being with her family, gardening, hiking, exercise and Lake Superior. She also regularly volunteers at the local homeless shelter, providing medical assessments and health education to individuals in need.

Sara Kocha, PA-C

Sara Kocha is a physician assistant with specialized experience in non-surgical bariatric medicine. She earned a Bachelor of Science in Health Sciences from Grand Valley State University before earning her Master of Physician Assistant Studies from Grand Valley State University in Grand Rapids, Michigan.

Following her formal education, Sara gained clinical experience in the areas of urology and hand surgery. Sara is a native of Marquette, Michigan and her interests outside of work include mountain biking, skiing and hiking with her husband and two children.

“Weight loss is a personal journey and I am committed to supporting them every step of the way. My goal is to help create a personalized plan that is tailored to their individual need and help them achieve that goal.”

Todd Vroegen, PA-C

Todd has been working in bariatric surgery since July of 2002. He was born and raised in Kalamazoo, Michigan, and graduated from Calvin College in 1986. He received his physician assistant degree from Western Michigan University in 1998.

He is married with five children and enjoys camping and sailing.

Matthew Seerveld, PA-C

Matt grew up in Denver, CO, and moved to Grand Rapids, MI, in 1985. He graduated from Calvin College in 1989 and attended Western Michigan University (WMU) for his education and training as a physician assistant. Matt also completed his surgical residency through WMU and Butterworth Hospital. His Master’s degree was obtained through the University of Nebraska.

After working in neurosurgery for nine years and vascular surgery for one year, he transitioned to bariatric surgery, joining the UP bariatric team in 2003. Matt has been married to his wife, Julie, since 1990. They have three children.

Jessica Tripp, DNP, FNP-C

Jessica has been a registered nurse (RN) for more than 10 years—first at the University of Michigan Health System in Ann Arbor, MI, and most recently in family medicine at UP Medical Group - Family Medicine | Lakewood. Following her time as an RN, Jessica returned to Northern Michigan University to earn her Doctorate in Nursing and Family Nurse Practitioner degree.

"I have always been drawn to the relationships you can build as a healthcare provider. When I worked as a nurse, those relationships may have lasted only one shift, but I knew I was making a difference. Now as a nurse practitioner in bariatric care, I am passionate about partnering with patients throughout their weight-loss journey—building lasting relationships that support long-term health, confidence and quality of life."