Accountable Healthcare Holdings Corp, a Boca Raton, Fla.-based healthcare staffing provider, announced the appointment of Lynne Mathews as chief operating officer. Mathews has more than 20 years of experience as an executive in the healthcare sector, having most recently served as regional operations director at DaVita SOURCE. Prior to joining DaVita, Mathews served as the executive vice president of operations at Medical Staffing Network.