Doctors & Staff


Tim Hartzler, NP

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Tim Hartzler started working with GSI at our Wadsworth office location in January 2018. He previously worked as a hospitalist nurse practitioner at an academic medical center.  He received his bachelor’s degree from the University of Virginia in 2012 and his masters from Virginia Commonwealth University in 2016.  Tim’s bedside nursing experience includes inpatient physical rehabilitation, medical/surgical and intensive care.

Originally from Indiana, Tim moved to the Commonwealth of Virginia in 2002. In his spare time he enjoys playing guitar, watching UVA sports with his wife, Kimberly, and going on walks with his dog, Yoshi.

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Mary Kathleen Engelken, NP

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Mary Kathleen Engelken joined GSI as a Nurse Practitioner in 2017 and works out of the Memorial Regional Medical Center location. She received her bachelor’s degree from York College of Pennsylvania in 2009 and her master’s degree from Virginia Commonwealth University in 2017. In 2017, Mary Kathleen received the Outstanding Student Award by the Virginia Council of Nurse Practitioners Richmond Region.

She has 10 years of experience as a registered nurse in hospital settings with a focus on critical and emergency care. Mary Kathleen is from Western Maryland and grew up living abroad in the Middle East but has lived in Richmond since 2011 with her husband and son. In her free time, she enjoys spending time with her family, running, traveling internationally, and putting her Spanish language skills to use through volunteer efforts in the Latin American community.

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Kelley Osborne, NP

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Kelley Osborne is an ANCC board certified family nurse practitioner, as well as an ASMBS certified bariatric nurse. Kelley works at our Wadsworth office, primarily with Dr. Omer Khalid.

She received her bachelor’s degree in liberal arts from Virginia Tech and originally worked at GSI as a front desk and medical assistant; an experience that led her to seek her advanced nursing degrees. After graduating nursing school in Boston, she spent three years working as a nurse practitioner in the Gastrointestinal Surgery Department at Hospital of University of Pennsylvania and then three years as director for the Sibley Center for Weight Loss Surgery in Washington, D.C.

She was born and raised in Richmond and is excited to be with the practice. Happily married, she is the busy mother of three young children who enjoys gardening and reading in her free time.

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Will Warren, PA

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  • Primary Location: St. Mary’s Hospital

Will is located at St. Mary’s Hospital where he assists Drs. Talreja and Thanjan. He received his bachelor of science degree in biology from the University of Georgia and then went on to complete his master of physician assistant degree at Eastern Virginia Medical School in Norfolk, Va. Prior to joining Gastrointestinal Specialists. Inc., Will worked in emergency medicine and orthopedic surgery.

Born and raised in Richmond, Will and his wife, Lindsay, enjoy cooking, spending time with their dog, trying new restaurants, traveling, running, college football, and do-it- yourself home projects.

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Molly Sandel, NP

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  • Primary location: St. Mary’s Hospital

Molly graduated from Virginia Commonwealth University’s Adult-Gerontology Acute Care Nurse Practitioner program in 2016. She joined Gastrointestinal Specialists, Inc., in 2017 after a fellowship in critical care at VCU. At GSI, she is primarily located at St. Mary’s hospital and works very closely with Drs. Abou-Assi, Seeman, Srivastava, Talreja and Thanjan.

Prior to becoming a nurse practitioner she worked in a medical intensive care unit where she gained valuable experience in the care of acutely ill patients and saw a wide variety of gastrointestinal illnesses. She is an active member of the Virginia Council of Nurse Practitioners and serves as the secretary for the Richmond region.

Originally from Botetourt County, Virginia, Molly has enjoyed living in Richmond since 2005, when she began the nursing program at VCU. In her free time, she enjoys traveling with her husband, playing tennis and board/card games, water and snow skiing, and working out.

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Rebecca Bae, PA

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Rebecca is a native Floridian, graduating summa cum laude from the University of Florida with a background in health science and Spanish. She completed her training as a physician assistant (PA) at Eastern Virginia Medical School from where she graduated with honors and was given the Eugene A. Stead Award, presented to one graduate who exhibited overall excellence in both clinical and didactic settings.

Before PA school, she worked in a psycho-oncology research lab studying the biopsychosocial interactions of gynecologic cancers. It was here that she became passionate about the mind-body connection and how physical health heavily influences mental well-being and vice versa. She practices medicine with this holistic philosophy of care. Rebecca has long been interested in gastrointestinal disorders for their vast interaction with every other body system and power to influence quality of life. Her training in this realm took place in the general surgery setting, emergency department, oncology unit at Johns Hopkins University, inpatient and outpatient internal medicine, and (her favorite) Gastrointestinal Specialists, Inc. as a PA student. She is excited to work with such a wonderful group of practitioners.

In her free time, Rebecca enjoys outdoor activities and playing board/card games with her wonderful husband. She also delights in her church and missions involvement and is long-time adult and pediatric hospice volunteer.

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Stephanie B. Herndon, NP

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Stephanie Herndon has been an Acute Care Nurse Practitioner since 2004. She has worked in gastroenterology since 2011 and joined GSI in 2014. She works closely with Drs. Michael Farrell, William Brand, and Ben Bradenham at both the Henrico Doctor’s Forest and Parham Doctor’s Hospital locations, seeing both office patients and inpatients.

Stephanie received both her undergraduate and master’s degrees from Virginia Commonwealth University. Prior to discovering her passion for gastroenterology, she worked as a nurse practitioner in various other areas, including pain management, occupational health, and interventional radiology. Before becoming a nurse practitioner, she spent 3 years as a registered nurse in the emergency room at Henrico Doctor’s Forest, where she gained great experience in the care of acutely ill patients. She is a member of the Virginia Council of Nurse Practitioners and the American Academy of Nurse Practitioners and has served as a preceptor for the School of Nursing at Virginia Commonwealth University.

Born and raised in Richmond, Stephanie is the proud mother of one boy. In her free time, she enjoys shopping, reading, listening to music, cooking/baking, and spending time with her family.

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Mandi M. Wolfe, NP

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Mandi Wolfe joined GSI as a nurse practitioner in 2013. She works at St Francis hospital and office with Drs. Ramy Eid and Diego Baltodano.

She received her master’s degree in nursing at the University of Alabama in Huntsville, Alabama, specializing in family medicine. Prior to joining GSI, Mandi worked for a large GI practice in South Carolina for several years. She has also worked as an RN in the cardiac ICU/cardiac cath lab and neuro/trauma ICU.

Originally from Alabama, Mandi has called the Richmond area home for the past couple of years. She is happily married and the mother of two young girls. She enjoys reading, baking, and knitting in her free time.

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Elizabeth A. Bowers, NP

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Elizabeth Bowers has been a Family Nurse Practitioner with GSI since 2002, working primarily with Drs. Stephen Clement, Ramy Eid and Diego Baltadano.

Her specialty focuses on care of the individual from birth through death in a holistic approach to treatment and the prevention of disease. Since becoming a Nurse Practitioner, she has focused exclusively on gastroenterology with continuing education and seminars on a regular basis. Prior to joining our practice, Elizabeth spent 10 years as an RN in the Richmond, Va., and Philadelphia, Pa., regions caring for intensive care, coronary care and pediatric ICU patients.

Born in the Philadelphia area and raised in the Poconos, Elizabeth has called the Richmond area her home for the past 20 years. She is happily married and a busy mother of a girl and a boy. In her limited free time, she enjoys reading, cooking, Tae Kwon Do, visiting family and friends, and gardening.

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