Nuclear Medicine

By now, perhaps you’ve heard about the rather “well”: “publicized”: story to appear in “Science”: tomorrow.

[Update: Here’s the “abstract”:;324/5923/98?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=frisen%2C+j&andorexacttitle=or&andorexacttitleabs=or&andorexactfulltext=or&searchid=1&FIRSTINDEX=0&sortspec=relevance&fdate=4/1/2009&tdate=4/30/2009&resourcetype=HWCIT,HWELTR of Bergmann et al., “Evidence for Cardiomyocyte Renewal in Humans.”]

No? It involves cadavers and atmospheric nuclear testing. “For real”:

Cell turnover rates can easily be measured in animals by making their cells radioactive and seeing how fast they are replaced. Such an experiment, called pulse-labeling, could not ethically be done in people. But Dr. Frisen realized several years ago that nuclear weapons tested in the atmosphere until 1963 had in fact labeled the cells of the entire world’s population.

The nuclear blasts generated a radioactive form of carbon known as carbon-14. The amount of carbon-14 in the atmosphere has gradually diminished since 1963, when above-ground tests were banned, as it has been incorporated into plants and animals or diffused into the oceans.

In the body, carbon-14 in the diet gets into the DNA of new cells and stays unchanged for the life of the cell. Because the level of carbon-14 in the atmosphere falls each year, the amount of carbon-14 in the DNA can serve to indicate the cell’s birth date, Dr. Frisen found.

Four years ago he used his new method to assess the turnover rate of various tissues in the body, concluding that the average age of the cells in an adult’s body might be as young as 7 to 10 years. But there is a wide range of ages — from the rapidly turning over cells of the blood and gut to the mostly permanent cells of the brain.

Long story short, they found that the heart muscle actually regenerates slightly over a human lifetime.

Usually, this sort of thing would be called a “natural experiment”:, but that label doesn’t seem quite appropriate here.

_Unnatural_ experiment?

_Accidental_ experiment?

Sure, it doesn’t make up for excess cancers from atmospheric nuclear testing, but it’s pretty neat anyhow.

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