Professional Staff

William O'Riordan, M.D. | Chief Medical Officer

La Mesa, CA

Dr. William O’Riordan, Chairman of the Board and Chief Medical Officer, founded eStudySite in 1999 along with twelve healthcare providers with whom he’d performed research for over ten years. Dr. O’Riordan has been involved in emergency medicine for more than thirty years at St. Francis Medical Center, Paradise Valley Hospital and Sharp Chula Vista Medical Center. His academic appointments include Harbor General Hospital–UCLA Medical Center and UCSD. His nineteen years of clinical investigation has been performed at Paradise Valley Hospital and Sharp Chula Vista Medical Center. As Principal Investigator, he has directed over 70 studies including cSSSI, Stroke, Acute Myocardial Infarction, Unstable Angina, Sepsis, Septic Shock, Hospital & Community Acquired Pneumonia, Hepatitis C, Atrial Fibrillation, Congestive Heart Failure, Hyponatremia, Complicated Appendicitis, UTI/Pyleonephritis, Occluded Central Venous Access Devices, genomic studies and more. He has served as Chief of Staff at Paradise Valley Hospital and President of the American College of Emergency Physicians in California. Dr. O’Riordan has also served on numerous advisory adjudication committees including AstraZeneca, Basilea Pharmaceutica, Aventis Pharmaceuticals, Inc., HoechstMarionRoussel among others. He is an examiner for the American Board of Emergency Medicine and a Fellow of the American College of Emergency Physicians. Dr. O’Riordan earned his medical degree from the University of Kansas Medical School and is licensed in Kansas and California.

Paul Manos, D.O. | Assistant Medical Director

Oceanside, CA

Dr. Paul Manos, one of the original founders of eStudySite in 1999, currently serves as Assistant Medical Director, co-directing clinical research studies for the company. He is Director of Emergency Services at Paradise Valley Hospital, where he has been an Emergency Staff Physician and Associate Medical Director. He was also Staff Physician at Sharp Chula Vista Hospital. Dr. Manos has been involved as Sub Investigator in numerous clinical investigations including Sepsis, Stroke, Hospital & Community Acquired Pneumonia, Skin/Skin-Structure Infections, S. aureus Bacteremia, cSSSI, and Urinary Tract Infection. Certifications include ACLS Instructor and Provider, Trauma Ultrasound; Diplomate of the American Board of Emergency Medicine; Fellow of the American Board of Emergency Medicine; and Fellow of the American Academy of Emergency Medicine. Dr. Manos received a Bachelor Science degree at the University of Southern California and earned his Medical Degree in 1993 from Midwestern University Chicago College of Osteopathic Medicine. He completed his Residency at Wayne State University, The Detroit Medical Center – Grace Hospital in 1997.

Alison McManus DNP, FNP-BC | Principal Investigator

Chula Vista, CA

Alison McManus Dr. Alison McManus joined eStudySite in 2007 as a Sub-Investigator and subsequently assumed the role of Principal Investigator at Sharp Chula Vista Hospital.  Alison completed her Masters in Nursing as a Nurse Practitioner at the University of San Diego and her Doctorate of Nursing Practice at Rush University in Chicago.  Alison is a Board Certified Family Nurse Practitioner and a Certified Emergency Nurse.  She has over 20 years of experience in the Emergency Department.  Her clinical research experience includes; complicated skin infections, community acquired pneumonia, influenza, anemia, diabetes, vaccines, and hepatitis C.





J. Scott Overcash, M.D. | Principal Investigator

Chula Vista, CA

J. Scott Overcash J. Scott Overcash, M.D. joined eStudySite in 2012 and is the Principal Investigator at our Sharp Chula Vista site.  Dr. Overcash is a board certified Emergency Physician with over 10 years of clinical and research experience.  He attended the University of North Carolina School of Medicine where he obtained his M.D. degree and completed their highly ranked Emergency Medicine residency program.  Throughout medical school and residency he conducted academic NIH funded research which resulted in journal publications and national presentations.  Dr. Overcash practiced Emergency Medicine in several locations throughout the country before settling in San Diego in 2008.  He has practiced Emergency Medicine at Sharp Grossmont Hospital since 2008 where he has been involved in hospital Quality Assurance as a member of the Sharp Grossmont Supervisory Committee since 2010. Dr. Overcash has been awarded the Sharp Health Guardian Angel award for clinical appreciation by his patients each year since 2011.  Dr. Overcash is a Diplomate of the American Board of Emergency Medicine,  a Fellow of the American Board of Emergency Medicine, board certified by the American Academy of Anti-Aging, and an active member of the Association of Clinical Research Professionals .  As a clinical investigator he has participated in and overseen clinical trials in all clinical phases of development and in multiple therapeutic areas.  His work has been published in national peer reviewed journals including the New England Journal of Medicine.  Areas of research expertise include Acute Bacterial Skin and Skin Structure Infections (ABSSI), chronic Hepatitis C, Community Acquired Pneumonia (CAP), Type 2 Diabetes Mellitus, acute Influenza, Venous Thromboembolism prophylaxis, Urinary Tract Infection, and novel  vaccine development.

Sandra Win, M.D. | Principal Investigator

San Francisco, CA

Dr. Sandra Win​​​​​​​​​​ is the Principal Investigator of Quest Clinical Research. Dr. Win has professional interests of chronic liver disease, infectious diseases, genetics and genomics, and clinical research on chronic hepatitis B & C, HIV, other infectious diseases, and fatty liver disease.

Dr. Win grew up in the upper Midwest in Southern Wisconsin and Northern Illinois. Her hobbies include photography, hiking, baking, reading, playing with her dog, and spending time with her family. Her public service interests include giving community health education talks and mentoring and teaching medical students and resident physicians.

Heidi Kabler, M.D. | Principal Investigator

Las Vegas, NV

Dr. Heidi Kabler joined eStudySite in 2012 as a Sub-Investigator and subsequently assumed the role of Principal Investigator at Sunrise Hospital in Las Vegas, NV.  Dr. Kabler completed her Bachelor of Science degree, graduating summa cum laude, from Duquesne University in Pittsburgh, PA.  She earned her medical degree from Wright State University School of Medicine in Dayton, Ohio.  She went on to complete her residency in Emergency Medicine at Wright State University where she was also named Chief Resident.  Dr. Kabler is board certified in Emergency Medicine, and after residency she moved to Las Vegas, NV to practice Emergency Medicine with Fremont Emergency Services.  Dr. Kabler is now a physician owner with Advance Care Emergency Services.   ACES is an independent group of Emergency Medicine physicians who practice in both Las Vegas, NV as well as in Bullhead City, Arizona.  Her clinical research at eStudySite includes Complicated Skin Infections, Clostridium Difficile,  Influenza, Hepatitis C, Diabetes, and Oral Nutritional Supplements.

Elliot Shin, M.D. | Principal Investigator

Las Vegas, NV

Dr. Dr. Elliot Shin serves as the principal investigator in the Las Vegas site. He graduated from Rutgers University as a Henry Rutgers Scholar in 1991, obtained a master’s degree in Nuclear Physics at Rosalind Franklin University of Health Sciences/The Chicago Medical School where he also received his medical degree in 2000. He then completed his residency training in 2003 at In His Image Family Practice Residency Program where he was also ordained as a medical missionary. Dr. Shin is a board certified family physician.

Dr. Shin founded Operation H.O.P.E., Inc. (Helping Other People Everywhere) in October of 2009 to invite the public to join with him in providing comprehensive solutions to the homeless and underprivileged populations worldwide. Operation H.O.P.E. provides innovative programs to equip, transform, and empower these individuals to become leaders in their own family and community. Since 2010, HOPE Clinic has seen over 14,000 uninsured low-income patients and continues to provide service and support to the community.

Steve Mannis, M.D. | Principal Investigator

Oceanside, CA

Dr. Steven Mannis serves as principal investigator in Oceanside and he's been an emergency medicine physician for over 25 years. Dr. Mannis also serves as medical director at Vista Detention Facility.  Dr. Mannis received his bachelor’s degree at University of California Santa Cruz, medical degree at Autonomous University of Guadalajara, and completed an emergency medicine residency in Toledo, Ohio at St. Vincent’s and Toledo Hospital. Dr. Mannis’ research experience includes, but is not limited to: skin infections; pneumonia; hepatitis; influenza; diabetes; and other infectious diseases.  He has clinical experience in general medicine including: hypertension; pain management; cardiovascular diseases; dermatology; and pediatrics.

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Current and Upcoming Studies

Dermatology: Actinic Keratosis Rosacea

Acute Studies: Abscess/Cellulitis/Wound Infections Urinary Tract Infections

Chronic Diseases: Type 2 Diabetes Hepatitis C HIV Osteoarthritis Chronic Lower Back Pain Uterine Fibroids Endometriosis Fatty Liver/NASH

Other: Healthy Volunteers Migraines C.difficile infection Anemia

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