Fwd: Cigarette smoke causes breaks in DNA

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From: "califpacific" Wed, 06 Oct 2004 08:56:42 -0000 Cigarette smoke causes breaks in DNAhttp://www.cancerfacts.com/Home_News.asp?CancerTypeId=4 & NewsId=1737Cigarette smoke causes breaks in DNASource: (cancerfacts.com)Thursday, September 30, 2004PITTSBURGH – Oct. 1, 2004 – Scientists have long known that cigarettesmoke causes lung cancer, but until now, no one has ever shown themechanism that triggers the cascade of events resulting in cancerouslung cells.Researchers led by Dr. William Saunders of the University ofPittsburgh are the first to show that cigarette smoke causeschromosome instability.

Their research shows how just one or two puffsof a cigarette can cause breaks in DNA leading to defects in a cell'schromosomes. Such genetic instability can result in irreversiblechanges in genetic information being passed to a newly divided cell."Double-stranded breaks are considered the most mutagenic type of DNAdamage because the broken ends can fuse to other chromosomes in thecell," Saunders said in a news release. "Chromosome fusion isdetrimental to normal chromosome segregation, which in turn leads togenetic imbalances."The research findings will be reported Tues. Oct. 5 in Pittsburgh atthe 35th Annual Meeting of the Environmental Mutagen Society,entitled, "Genes, Mutations and Disease: The EnvironmentalConnection," taking place Oct. 2 to 6. The study will also appear inan upcoming article in the journal Mutation Research.Before a cell undergoes division, its DNA is duplicated and compressedinto identical

copies of each chromosome inside the cell nucleus. Thechromosomes are then segregated during cell division, so that eachdaughter nucleus receives a complete copy of the genetic material. Thestage when chromosomes are segregated and become separated is calledanaphase. Normally, each set of chromosomes is pulled with equal forcein opposite directions so that each daughter cell receives the samenumber of chromosomes.But when the researchers exposed cells in culture to cigarette smoke,they found that the fused chromosomes were being pulled simultaneouslyfrom both directions much like a piece of taffy, forming so-calledanaphase bridges between its two ends. Eventually, these chromosomeseither tear apart, leaving two broken pieces, or if they don't breakapart, the abnormal, elongated chromosomes may persist after anaphaseis completed. Either way, a major change in the structure of thechromosomes is the end

result.Cigarette smoke contains some 5,000 organic compounds, includingchemicals known to cause cancers. While the researchers did not exposecells to actual puffs of smoke, the cigarette smoke condensate theyused was derived from burning real cigarettes and obtained from theR.J. Reynolds Tobacco Company. Containing mostly particulates, theextracted smoke was liquefied as part of a solvent mixture before thecells were exposed to it."Others have found the presence of anaphase bridges is correlated withchromosome instability in cancer cells. Because cigarette smoking islinked to oral, larynx, lung, bladder and esophageal cancers, ourresults showing that cigarette smoke can produce anaphase bridges anddestabilize a cell's chromosomes have added significance," said Saunders.According to their results, the development of anaphase bridges andchromosome instability is most likely due to reactive oxygen speciesthat form

as the cell is exposed to the various chemicals in smoke.Treating the smoke-exposed cells with different antioxidants, agentsthat block formation of reactive oxygen species, prevented mostoccurrences of anaphase bridge formation and significantly reducedgenomic imbalances.Please pass this message or article on to someone else so that they may learn also.Community Newsletters.http://www.alternative-medicine-newsletter.infoCommunity Message Boards.http://www.alternative-medicine-message-boards.info"Do not let either the medical authorities or the politicians mislead you. Find out what the facts are, and make your own decisions about how to live a happy life and how to work for a better world." - Linus PaulingGetting well is done one step at a time, day by

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