Only when outside and inside channels line up with each other to form a single tube can the ions begin to flow.

ECONOMIST: Medical diagnostics

Vintage Tube logos form the background of a commemorative Oyster card to mark the 150th anniversary of London Underground rail service in London.

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Dirks showed that some of the immature-looking cells from his patients could form tumorlike clumps in the test tube, unlike most other cells from the tumors, but he didn't have a method to pluck out the stem cells.

FORBES: Cancer Killer

The more promising candidates were then cooked up and injected into a test tube holding a notoriously resistant form of ovarian cancer preserved from years ago.

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They could be used to build an artificial artery in a test tube or the stem cells could be injected straight into the heart and they could form within it.

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The stent, a metal-mesh tube, keeps the artery from closing up again after the balloon is removed, but scar tissue can form over the metal, re-blocking the artery.

FORBES