The mean systemic concentrations of Aα-VAL³⁶⁰in young and older healthy adults. Aα-VAL³⁶⁰ is an NE-specific fibrinogen cleavage product. The cleavage product was measured by enzyme-linked immunosorbent assay in plasma in triplicate from all individuals, and healthy subjects aged over 65 and under 35 were compared (n = 20 each group). The mean concentration is shown for each group with the standard error given. * indicates significant difference from young adults (P < .05).