The N-terminus and a 4000 molecular weight peptide from the mid portion of the N-terminus of the atrial natriuretic factor prohormone each circulate in humans and increase in congestive heart failure. - Winters,C.J.; Sallman,A.L.; Baker,B.J.; Meadows,J.; Rico,D.M.; Vesely,D.L. (Circulation, 1989)