PITTSBURGH, Sept. 30 The amount of smoke in just one or two puffs of a cigarette can cause breaks in DNA and defects to a cell's chromosomes, leading to irreversible changes in genetic information being passed to a newly divided cell, according to University of Pittsburgh researchers. Their findings, to be reported Tuesday, Oct. 5 at the 35th Annual Meeting of the Environmental Mutagen Society, are the first to show that cigarette smoke causes chromosome instability.

The meeting, "Genes, Mutations and Disease: The Environmental Connection," will be held Oct. 2 to 6 at the Pittsburgh Hilton and Towers.

While most research has focused on the changes in DNA sequence caused by cigarette smoke, little attention has been given to how smoke affects genomic stability of cells. In laboratory studies using human fibroblasts, common cells found in connective tissue, William S. Saunders, Ph.D., and colleagues discovered that exposure to even a small amount of cigarette smoke condensate equal to about 1/25 of a cigarette caused breaks to both strands of DNA and compromised the integrity of the cell's chromosomes.

Cigarette smoke contains some 5,000 organic compounds, including chemicals known to cause cancers. While the researchers did not expose cells to actual puffs of smoke, the cigarette smoke condensate they used was derived from burning real cigarettes and obtained from the R.J. Reynolds Tobacco Company. Containing mostly particulates, the extracted smoke was liquefied as part of a solvent mixture before it was exposed to the cells.

"Double-stranded breaks are considered the most mutagenic type of DNA damage because the broken ends can fuse to other chromosomes in the cell. Chromosome fusion is detrimental to normal chromosome segregation, which in turn leads to genetic imbalances," explained Dr. Saunders, associate professor of biological sciences, University of Pittsburgh School of Arts and Sciences, and a researcher with the Or
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30-Sep-2004

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