Medical Services Directory

  • Yvette Rhea-Burg joined Columbia Health in 1999. She is a scheduling coordinator at Medical Services.

  • Yonette Douglas joined Columbia Health in 2012.

  • Education:

    • New York University, Bachelor of Science in Nursing
    • Hunter College, BA

    Certifications and Licensure

    • Registered Nurse
    • BLS
    • Certified School Nurse

    Professional Experience

    • Bone Marrow Transplant- Collected, analyzed and reported statistical and clinical data in support of BMT cancer research activities.
    • Women's Health- Breast Surgery and Fertility
    • School Nurse

    Yaffa is fluent in Hebrew.

  • Veronica joined Columbia Health in 2018.

  • Valerie Noel is a medical assistant at Columbia Health, Medical Services.

  • Tonia Lesesne joined Columbia Health in 1991.

  • Tahshann S. Richards, D.O., M.P.H., joined Columbia Health in November 2015. Tahshann is a board-certified family physician with special interests in reproductive health, behavioral health, health promotion and osteopathic manipulative medicine. After receiving her medical degree from the University of Medicine and Dentistry of New Jersey (now Rowan University), Tahshann returned to her hometown of the Bronx to complete her family medicine residency at St. Barnabas Hospital. She spent the early part of her career as staff physician in St. Barnabas Hospital’s Adolescent Medicine Department, where she helped write and implement a New York State Department of Health Comprehensive Adolescent Pregnancy Prevention grant, as well as help develop the Teen Health Center and supporting Youth Development programs. Tahshann later fulfilled her National Health Service Corps Scholarship service commitment at the Union Community Health Center, Bronx.

    Prior to her transition to college health, she served as family medicine residency associate program director at St. Barnabas Hospital. She remains committed to improving the health of underserved communities, in addition to promoting the overall health and wellbeing of Columbia students, affiliates and their families.

  • Sharon Sperling-Silber joined Columbia Health in 2011, when she and her husband, three children, dog and cat returned to New York City after living in the Washington, D.C., area for 15 years. As a nurse practitioner, her areas of focus are on wellness through nutrition, exercise and on sexual health. Sperling-Silber is also an adjunct lecturer in the nursing department at New York City College of Technology. 

    Prior to joining Columbia, Sperling-Silber worked in the operating room in a level-2 trauma hospital. Outside of work she enjoys group fitness, especially yoga and spin classes as well as outdoor cycling and following and Paleo/Keto diet and lifestyle.

  • Samuel Schnapp joined Columbia Health in 1993. Trained as a nurse practitioner, Sam has a background that includes home care, rehabilitation medicine and post-surgical patient care. His original commitment to teaching patients about health maintenance and disease prevention has been strengthened at Columbia Health by the students he works with who, he notes, "Often take a very active and positive role in maintaining their own health.”


  • Roseann Neuberg joined Columbia Health in 2007. She began her career in women's health, working at several hospitals, two birthing centers, as well as Planned Parenthood. She transitioned to student health, where she worked at the Fordham University Health Service for 12 years. As a mother of three college-age children, Roseann feels a strong connection to the student population. She enjoys the diversity of student health, and focuses on education and prevention as integral parts of treatment.

  • Education:

    B.A. from CUNY

    B.S.N. from CUNY

    Certification and Licensure:

    Registered Nurse

    Professional Experience:

    Emergency Department

    NSG Supervisor

    Occupational Health

    School Nursing

  • Dr. Rick O’Keefe joined Columbia Health in 2004. Prior to Columbia, Rick worked in academic family medicine with a focus on increasing the quality and access to care for underserved communities in urban areas. O’Keefe developed programs that care for marginalized and LGBT adolescents in school-based and street settings.  

    As part of Columbia Health, Rick is a member of the men's health team, serves as medical advisor for Gay Health Advocacy Project and facilitates the Integrative Medicine Workgroup. He earned an M.A. in Social and Organizational Psychology from Teachers College, Columbia University in 2015.

  • Ramona Lanzo joined Columbia Health in 1994. Prior to Columbia, Ramona worked as a laboratory technologist in various medical facilities and hospitals. She has been in the laboratory services field since 1985. Ramona attended Bronx Community College, where she majored in medical laboratory technology, and Lehman College with a concentration health services administration.

  • Patty joined Columbia Health in 2018.

  • Monica joined Columbia Health in 2018 as the Associate Director of Nursing.  She brings to Columbia considerable college health experience having been part of the student health team at Brown University.

  • Dr. Mary O'Brien joined Columbia Health in 1993. Prior to Columbia, Mary worked as the associate director of the emergency room at St. Luke's Hospital. 

  • Martine Duplan joined Columbia Health in 2017.

  • Marcia Sutherland is a medical assistant at Columbia Health Medical Services.

  • Laura Maudene Nelson is a nutritionist and instructor at the Columbia University Institute of Human Nutrition and teaches graduate nutrition, medical, dental, nursing, and public health students.

    She has been active with the American Diabetes Association, where she serves on the national board of directors, and the American Heart Association, where she previously served on the board of directors of the New York City Affiliate, the Advisory Council, Heart-at-Work, Nutrition Counseling Workshop Planning Committee, and as a member of the Nutrition Committee. She has also served on the editorial board for RN Magazine.

    Maudene volunteers for the American Diabetes Association making public presentations and reaching out to elected officials to advocate for people with diabetes. She also coordinates opportunities for work site and community nutrition projects.

    Best nutrition advice: Eat mostly foods that grow from roots not feet, and, watch out for shiny food – it may be glazed not polished.


    • B.S., Human Nutrition, Cornell University
    • M.S., Public Health Nutrition, Teachers College, Columbia University. 

    Certifications and Licensure

    • Registered Dietitian
    • New York State Certified Dietitian-Nutritionist
    • Certified Diabetes Educator

    Professional Experience

    • Instructs classes on nutrition, exercise, and weight management to adults and children patients at the Naomi Berrie Diabetes Center, New York City
    • Nutrition assessments and counseling on home visits for Care Coordination Services, Philadelphia, PA
    • Nutrition counseling in worksite wellness for Metropolitan Life Insurance Company and Merrill Lynch
    • Nutrition counseling in the student health service of Columbia University



  • Dr. Tombackwas born and raised in Freehold, NJ.  She loves exploring NYC and going to Broadway shows.


    • Residency:  Hunterdon Medical Center Family Medicine Residency Program, 2005
    • M.D., UMDNJ-New Jersey Medical School, 2002
    • B.A., American History, University of Pennsylvania, 1996

    Certifications and Licensure:

    • M.D., 2002
    • New York State Board of Medicine


    • American Association of Family Practitioners


  • Jennifer joined Columbia Health in 2018. She worked as a RN in the ambulatory care setting for 4 years, working with various patients of all ages. Her interests include women's health and public health.

  • Jamie Zhang joined Columbia Health in 2017.

  • Dr. Gregoriy Grenader joined Columbia Health in 2012. Gregoriy earned his BA in psychology from CUNY Brooklyn College, graduating with honors. Prior to earning his DO from New York College of Osteopathic Medicine, he was a certified emergency medical technician. He completed his post-graduate residency training in family practice at North Shore/Long Island Jewish Plainview Hospital in Long Island, New York. Gregoriy enjoys home improvement, music, and traveling.

  • Elizabeth Shelley, DNP, FNP-BC joined Columbia Health in 2016.  She graduated from Barnard College in 2006 and played on the Columbia University’s Varsity Volleyball team during this time.  She later received her nursing degree from the University of Rochester School of Nursing and her family nurse practitioner as well as doctor of nursing practice from Columbia University School of Nursing. 

    Prior to Columbia, Elizabeth worked as a registered nurse on a medical neurosurgical unit, as a primary care nurse at Barnard Health Services, and as a private duty nurse in New York City before becoming a family nurse practitioner.  She worked as a family nurse practitioner at a federally qualified health service center in New York before joining Columbia Medical Services.



    • D.N.P., Doctor of Nursing Practice, Columbia University, School of Nursing
    • M.S.N., Family Health, Columbia University, School of Nursing
    • B.A., Neuroscience & Behavior, Columbia University, Barnard College


    Certifications and Licensure:

    • Certified by American Nurses Credentialing Center (ANCC)
    • Licensed to practice medicine in the State of New York
    • Basic Life Support (BLS)
    • Breastfeeding Specialist Certificate (BSC)


    Professional Experience:

    • Preceptor in ambulatory care for Columbia University School of Nursing student nurse practitioners
    • Family Nurse Practitioner in a Federally Qualified Health Center
    • Registered Private Duty Nurse in New York City
    • Registered Nurse at Barnard College
    • Registered Nurse at Strong Memorial Hospital


    Professional Memberships:

    • The Nurse Practitioner Association, Inc. (NPA) of New York
    • Sigma Theta Tau
  • Dr. Don Kreuz joined Columbia Health in 2009. Don has a very diverse medical background, which includes over ten years of experience in clinical academic medicine and a focus in men’s health. He has expertise in the diagnosis and treatment of sexually transmitted diseases and sexual dysfunction. He earned his M.D. from the Universidad Central del Este and B.S. from Rutgers University. Dr. Kreuz is also a clinical assistant professor of medicine at the New York University School of Medicine.

  • Dr. Dawn Mcallister is a Urgent Care Physician at Columbia Health. She studied medicine at the University Of Cincinnati College Of Medicine and then moved to New York to practice at The Family Medicine Residency Program at Montefiore. Afterwards she went to the Family Medicine Residency Program at Columbia University Medical Center in 1997 and taught medical students and residents there for about nine years as an Assistant Professor of Medicine in the Center for Family Medicine. 

    She moved away from the academic setting and worked at Community Health Centers where she could take care of patients regardless of their legal status or ability to pay for their health care. She has one son by birth who is now 16 years old and two by adoption from Ethiopia who are 15 and 10 years old. Dawn says she chose to come back to Columbia University in 2014 at the Student Health Service and truly enjoys with students, both optimizing health and treating health problems. As an androgynous lesbian mom, from a working class background, with African American sons,  Dr. Mcallister hopes to offer a welcoming and supportive presence in the lives of all the students who come to visit at Columbia Health.


    • M.D., University of Cincinnati
    • B.A., History, University of California, Berkeley

    Certifications and Licensure:

    • New York State Medical License
    • Board Certified: Diplomat of American Board of Family Medicine

    Professional Experience:

    • Assistant Professor of Medicine, Columbia University Medical Center, Center for Family Medicine
    • Federal Qualified Community Health Centers in New York City and Westchester
    • Montefiore Medical Center, Family Medicine Residency
  • David Carney joined Columbia Health in 2017. He served as a critical care nurse in Albany Medical Center Neuroscience Progressive Care Unit prior to moving back to New York City after living in New York's Catskill mountains for 10 years.


    • MSN, Excelsior College, anticipated Summer 2018
    • BA, Art History and Fine Arts, SUNY New Paltz
    • AS, Nursing, SUNY Columbia-Greene Community College
  • Darline Volcy joined Columbia Health in 2012.

  • Colleen S. Eng, DO, joined Columbia Health in 2014. Dr. Eng is a board-certified family physician who also performs osteopathic manipulative treatment. Prior to Columbia, she spent her career practicing as a family physician in Philadelphia and Bucks County, Pennsylvania, in Westchester County, New York, and on the Upper West Side in Manhattan. She completed her internship at the Hospital of the University of Pennsylvania and her residency training at Aria Health (formerly Frankford Hospital), where she served as chief resident.

    After a career in marketing and recruiting and the events of Sept. 11, 2001, Eng switched her focus to pursue a career in medicine. She received her medical degree from the University of Medicine and Dentistry of New Jersey School of Osteopathic Medicine (now Rowan University School of Osteopathic Medicine), and her undergraduate degree from Cornell University. She is a native New Yorker and an alumna of the Bronx High School of Science.

  • Colby Golder has provided nutrition therapy since she received a master’s degree in nutrition from Teachers College at Columbia University in 2009. As part of her clinical training in dietetics, Colby worked at the eating disorder unit of the New York State Psychiatric Institute. She was part of a multidisciplinary team that focused on the research and treatment of eating disorders for in-patient care.

    Most recently, Colby worked at the prestigious Renfrew Center for eating disorders in New York City. Colby was involved in every level of therapeutic care including the day program, the intensive outpatient program, and individual nutrition counseling. She gained vast experience in nutrition therapy for those struggling with anorexia, bulimia, binge eating disorder, compulsive exercise, and other forms of disordered eating. She routinely conducted weekly group sessions that focused on nutrition education, the management of therapeutic meals, and post-meal support therapy.

    In addition to her work in Health Services, Colby also works in a private practice focusing on nutrition, eating disorders, and weight management by working with patients to cultivate a healthy relationship with food.

  • Christine Napoleon is a medical assistant at Columbia Health, Medical Services.

  • Dr. Brenda Aiken joined Columbia Health in 2000. Brenda served as a physician before being promoted to director of Medical Services in 2012. She is also an assistant professor of clinical medicine at Columbia University Medical Center.

    Prior to Columbia, she was an assistant professor of medicine at Albert Einstein College of Medicine, as well as an assistant attending physician at the Allen Pavilion. She has worked closely with the faculty and staff of the residency program in social medicine at Montefiore Medical Center.

    Dr. Aiken has devoted her professional career to the comprehensive study of medical and health-related issues of under-represented communities.

  • Belgica Peguero is a medical assistant at Columbia Health, Medical Services.

  • Anna Combs joined Columbia Health in 1995. Prior to Columbia, Anna was employed with Kelly Temps and had several working assignments in customer service. She is originally from Brooklyn and joined the United States Army after high school. Anna’s interests include indoor and outdoor sports, music, and gardening.

  • Ann Marie Alexander is a health services assistant at Columbia Health.

  • I am a native New Yorker raised in Queens, NY.  I attended St. Francis College, Hunter College and received my B.S.N. from Pace University in 2005.  I was an ICU nurse from 2005-2018.


    B.S.N. from Pace University (2005)

    Certification and Licensure:

    Registered Nurse

    Professional Experience:

    NYU Langone Medical Center

    NY Presbyterian Hospital

    Beth Israel Hospital

    Mt. Sinai / St. Luke's Hospital

  • Andrea G. Andaya received her BSN from the University of Texas at Austin in 2006.  She became a commissioned officer in the Navy Nurse Corps in 2007 and cared for service members and their beneficiaries while stationed in the National Naval Medical Center Bethesda (now Walter Reed National Military Medical Center), Naval Hospital Okinawa (Japan), and Naval Hospital Lemoore (California).  She left the Navy in 2017. 


    B.S.N. from University of Texas at Austin

    Certifications and Licensure:


    Professional Experience:

    Staff nurse on medical-surgical unit at National Naval Medical Center Bethesda.  Staff nurse on post-partum unit at Naval Hospital Okinawa. Department head of mother/infant unit at Naval Hospital Lemoore.  Division officer of Ambulatory Procedures Unit. 

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