Brian Marquis
Brian Marquis serves as the Practice Contracted Administrator. Brian holds a Bachelor of Science degree in Health Management and Policy and a Master of Arts degree in Health Administration, both from the University of New Hampshire, and a Master of Science in Healthcare Leadership from Dartmouth College, The Dartmouth Institute.
Brian has spent most of his career supporting physician practices, both independent and hospital-affiliated, with strategic, financial and operational leadership. He splits his consulting work between leading private and hospital-employed practices as a contracted administrative leader and assisting clients in projects, such as practice evaluations, care model redesign, strategic planning and execution, and process and quality improvement. A significant amount of his time is spent providing business valuations within and outside of the health care industry for compliance, lending, and mergers and acquisitions.
Brian is active in his community. He currently serves on the Board of Directors for Portsmouth Christian Academy and of Durham Evangelical Church. Brian consults with the PCA basketball program serving in various coaching roles from junior high through high school.
Jennifer Marshall
Jennifer Marshall serves as the Director of Operations. A graduate of Rivier University, Jennifer has been a nurse since 2001 and has accumulated extensive experience in the medical field since 1996. She holds a Bachelor of Science in Nursing, a Master of Science in Nursing, and an MBA in Healthcare Administration.
With a strong leadership background, Jennifer has served in various leadership roles since 2017, bringing diverse healthcare experience from home care, skilled nursing facilities, to both inpatient and outpatient services. She is nationally certified by the American Nurses Credentialing Center (ANCC). Jennifer is also a member of the LPN advisory board for the Greater Lowell Technical School.
Outside of her professional life, Jennifer is a dedicated family-oriented individual who values quality time with her loved ones. She and her husband enjoy spending time with their adult children, making cherished memories during family gatherings and special occasions. A true travel enthusiast, Jennifer loves exploring new destinations and experiencing different cultures, often sharing these adventures with friends and family. An avid New England Patriots fan, she can often be found cheering them on during the football season. Jennifer resides in Londonderry, NH, where she enjoys a balanced lifestyle surrounded by nature and a strong sense of community.
David Thomas
David Thomas is a seasoned Human Resources professional at GSG, where he applies his extensive experience to foster a dynamic and productive workplace. Holding an MBA from Southern New Hampshire University (SNHU), David brings a strategic approach to HR, combining his educational background with over 14 years of expertise in the healthcare industry. His career has been defined by a strong commitment to leadership, talent development, and organizational growth.
David’s deep knowledge of healthcare operations and leadership principles has enabled him to drive impactful HR initiatives, optimize team performance, and support organizational goals. He has the ability to navigate complex challenges with a focus on people development.
Outside of his professional life, David is dedicated to his family. He actively supports his children’s athletic pursuits, attending their games and cheering them on as they excel in various sports. He also enjoys encouraging their personal growth and nurturing their individual passions.
Julia Poisson
Julia Poisson serves as the Practice Clinic Manager at GSGI. A graduate of the University of New Hampshire, Julia earned her Master’s in Nursing in 2012, following her Bachelor of Arts in Psychology from Ithaca College in 2008.
With a strong foundation in nursing, she began her career at Elliot Hospital, working as a staff nurse on a medical-surgical unit for several years. As her passion for leadership grew, Julia took on roles as a preceptor, charge RN, and eventually worked as a resource nurse for the past seven years. She earned her Med Surg Certification in 2021 and a Chemotherapy Provider certification in 2019, with experience working with oncology patients. In 2018, she was honored as the Medical Surgical Nurse of the Year by New Hampshire Magazine.
Julia is excited to take on a new challenge in her career at GSGI. Outside of work, she enjoys spending time with her family and friends, especially in the great outdoors. Hiking, reading, and experimenting with new recipes for her family are some of her favorite hobbies. Julia enjoys traveling and exploring new destinations, making memories and cherishing moments with her loved ones.