Dr. Clayton G. Johnsen

Alfred Simental is a General Surgeon practicing medicine in Loma Linda, California. Dr. Simental is highly rated in 16 conditions, according to our data. His clinical expertise encompasses Thyroid Cancer, Hyperparathyroidism, Anaplastic Thyroid Cancer, Thyroidectomy, and Parathyroidectomy.

Dr. Ninh T. Nguyen is a board-certified UCI Health surgeon who specializes in minimally invasive gastroesophageal surgery and bariatric surgery. He pioneered the development of laparoscopic esophagectomy and gastrectomy for the treatment of esophagogastric pathology and laparoscopic Roux-en-Y gastric bypass for the treatment of morbid obesity.Nguyen earned his medical degree at the University of Texas Health Science Center at San Antonio, Tex. He completed a residency in general surgery at Mount Sinai Medical Center, Miami Beach, Fla, followed by fellowships in surgical oncology and minimally invasive surgery at the University of Pittsburgh Medical Center.Nguyen is the John E. Connolly professor and chair of the UCI School of Medicine's Department of Surgery and chief of its Division of Gastrointestinal Surgery. He is also co-director of the minimally invasive surgery fellowship and associate director of the UCI Health H.H. Chao Comprehensive Digestive Disease Center.He was honored with the 2019 Outstanding Achievement Award by the American Society for Metabolic and Bariatric Surgery (ASMBS), of which he is an active member. He is also a member of the American College of Surgeons, the Association for Academic Surgery, the Society for Surgery of the Alimentary Tract, the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) and the American Surgical Association. In 2002, he received the Golden Scope Young Researcher Award from SAGES, in recognition of significant contribution to research in laparoscopic surgery.He is also past president of the ASMBS and served as the ASMBS representative on the Gastrointestinal Surgery Advisory Council for the American Board of Surgery. He is a former president of the North American Chapter of the International Federation for the Surgery of Obesity and has served on the editorial boards of theJournal of the American College of Surgeons,Surgical EndoscopyandAnnals of Surgery. He has been the principal investigator on numerous research grants and has published more than 250 peer-reviewed articles and book chapters. Dr. Nguyen is highly rated in 13 conditions, according to our data. His clinical expertise encompasses Hiatal Hernia, Hernia, Diaphragmatic Hernia, Gastrectomy, and Gastric Bypass.

John Lipham is a General Surgeon practicing medicine in Los Angeles, California. Dr. Lipham is highly rated in 20 conditions, according to our data. His clinical expertise encompasses Gastroesophageal Reflux Disease (GERD), Hiatal Hernia, Hernia, Endoscopy, and Gastrectomy.