Original sentence: Anti-aging medicine field has not joined the American Board of Medical Specialties.The American Academy of Anti-Aging Medicine (A4M) is a United States registered 501(c)(3) nonprofit organization which promotes anti-aging medicine
Edited sentence: The American Academy of Anti-Aging Medicine (A4M) is a United States registered 501(c)(3) nonprofit organization which promotes what it calls "anti-aging medicine," a field not recognized by the American Board of Medical Specialties