1/20: Sochi Olympics: Security tightens as new video threat surfaces; Groundbreaking stem cell treatment approved for MS patients

      |An Islamic militant group that claimed responsibility for suicide bombings that killed 34 people last month posted a video threatening to strike at the Winter Olympics in Sochi; and, Dr. Jon LaPook goes inside the trial and approval process for an experimental treatment using stem cells designed to make Multiple Sclerosis patients better.

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