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[IPk] OCRed article from New Scientist re diabetic damage mechanism

Dear All,

This is off-topic (i.e. nothing to do with pumps), but hope that it will
be of enough general interest that I'll be forgiven.

  ------- Forwarded message follows -------
Radical damage.

A single type of toxic molecule may destroy organs in diabetics.

BLINDNESS, kidney failure and nerve damage caused by diabetes can be traced
to a single mechanism in cells, say researchers in New York. If drugs could
be found that target this mechanism, they say, these complications could be
stopped in their tracks.

Diabetes leads to hyperglycaemia-excess glucose in the blood. This damages
nerves and the lining of blood vessels. When this happens in the retina, for
instance, it can cause blindness. Scientists already know of four major
biochemical pathways that give rise to this damage. "But there was nothing
connecting them," says Michael Brownlee of the Albert Einstein College of
Medicine in New York. So he and his colleagues set out to find the link.
Cells oxidise glucose to fuel their energy factories, or mitochondria. This
process involves a sequence of electron-transfer reactions called the
mitochondrial electron transport chain, which produces a free radical called
superoxide as a by-product.

Normally, cells are able to dispose of the small amount of superoxide they
produce. But too much glucose in the blood upsets the cell's delicate
balance. "If you push too many electrons through the mitochondrial electron
transport chain, it jams up. You start generating lots of superoxide," says
Brown-lee, who presented his team's findings at last week's meeting in
Jerusalem of the European Association for the Study of Diabetes.

Brownlee and his team took cells from cows and humans genetically modified
them to produce high levels of a protein called UCP1, which indirectly
reduces levels of superoxide.
Significantly, stopping the build-up of superoxide blocked the four pathways
that lead to diabetic complications. "They are all connected because they
are downstream of one thing-the superoxide production," says Brownlee.

The electron transport chain may also explain a phenomenon called
hyperglycaemic memory, in which cells that have been exposed to excess
glucose later develop complications even after glucose concentrations have
returned to normal. Brownlee suggests that excess superoxide can cause
mutations in mitochondrial DNA. These mutations would in turn lead to more
superoxide production, he says.

"This is a really fundamental and highly important discovery," says Phillip
Gorden, former director of the National Institute of Diabetes and Digestive
and Kidney Diseases near Washington DC. "It offers a lot of promise for
therapies." Anhl Ananthaswamy

Pat Reynolds
email @ redacted
   "It might look a bit messy now, but just you come back in 500 years time" 
   (T. Pratchett)
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