Science  09 Mar 2012:
Vol. 335, Issue 6073, pp. 1153

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  1. Transplant Procedure Helps Both Sides Get Along

    The immune system's job is to keep out foreign invaders—which can also mean attacking transplanted organs. Transplant recipients take immunosuppressive drugs for life so their bodies won't reject the new tissue—risking kidney damage, infections, heart disease, and increased susceptibility to cancer. Still, many transplants are eventually rejected. Adding some of the donor's bone marrow (which manufactures immune cells), can help—but if the donor's immune system takes over, it can attack the recipient's tissues, called “graft versus host disease” (GVHD).

    A clinical trial held at Northwestern University and described in Science Translational Medicine this week shows a way to evade both difficulties. Researchers at the University of Louisville in Kentucky engineered bone-marrow-producing cells from kidney donors to remove the cells likely to cause GVHD, while increasing “facilitating cells” that make the recipient's system more receptive to the transplant.

    Of eight recipients who received the treatment the day after the transplant, five were off immunosuppressants, with normal kidney function and no sign of GVHD, within a year. “It's likely that the facilitating cells increase regulatory T cells, which balance immune system activity,” says study co-author Suzanne Ildstad. “One patient says he's never felt better than when he was finally off immunosupression.”

  2. Spreading the Blame for The Mammoth's Extinction

    The wooly mammoth of North America, a 3-meter-tall Australian kangaroo, and hundreds of other species of oversized animals around the world may have been the victims of collusion between changing climate and human depredation, according to a new study this week in the Proceedings of the National Academy of Sciences.

    Zoologists Graham Prescott and David Williams and their colleagues at the University of Cambridge compiled extinction dates over the past few tens of millennia for 110 genera of megafauna across Australia, Eurasia, New Zealand, North America, and South America. They compared the timing of extinctions with the timing of the arrival of humans, of severe climate change, and of both. “It seems likely that both climate and human factors played a role,” says Prescott.


    Victims of a double whammy?


    The study “makes a clear case for there being an interaction” between humans and climate, says paleoecologist Anthony Barnosky of the University of California, Berkeley. “It shows what happens when two bad things happen at once.” However, ecological statistician Andrew Solow of Woods Hole Oceanographic Institution in Massachusetts worries “that too much of the detail was omitted. This is a first step.”