11.   Swine lungs, he was told, with the dark one resembling a human lung exposed to cigarette smoking.

12.   The scientists exposed human lung cells to BPDE, a powerful carcinogen produced in the body when a chemical in cigarette smoke breaks down.

13.   Then clumps of spores must be refined to precise specifications if they are to find their way into the human lung.

14.   These animal surfactants, he said, might be analyzed and their composition mimicked to help treat human lung disorders.

15.   He found identical fibers in more human lung tissue and used smoking machines to show inhaling also released fibers.

16.   Oxygen is too scarce, as is air pressure to force that small amount of oxygen through human lungs.

17.   Suthanthiran and his colleagues isolated human lung and bladder cancer cells that were treated with cyclosporine.

18.   The discovery was made while the researchers were studying effects of human milk on bacteria associated with human lung cancer.

19.   Tuberculosis is a serious, infectious disease that afflicts human lungs.