LOS ANGELES -- Hacking and gasping, Irma Ortiz could cart her groceries only so far before she'd catch other shoppers glaring at her. Mortified, she'd abandon her cart on the spot and bolt for the door. Frank Herrera could gun his dirt bike only so far before choking on the rush of air. Go. Stop. Go. Stop. Exasperated, he gave up riding. Ortiz, 44, and Herrera, 34, are odd candidates for lung transplants, being nonsmokers and having considerable youth on their side. How they lost 70 to 80 percent of their breathing capacity is no less astonishing. They acquired the...