Dr. Michael Van Natta is leaving Knoxville Hospital and Clinics effective next month. Knoxville Hospital and Clinics Public Relations Director Katrina Nelson confirmed Dr. Van Natta turned in his resignation Tuesday morning. Tuesday morning. Doctor Van Natta’s departure comes after he accepted a teaching position at Des Moines University. Van Natta has spent 10 years working at Knoxville Hospital and Clinics, where he specialized in Family Practice. His last day will be on August 29th.