The history of the Arctic Ocean during the Cenozoic era (0-65 million years ago) is largely unknown from direct evidence. Here we present a Cenozoic palaeoceanographic record constructed from >400 m of sediment core from a recent drilling expedition to the Lomonosov ridge in the Arctic Ocean. Our record shows a palaeoenvironmental transition from a warm 'greenhouse' world, during the late Palaeocene and early Eocene epochs, to a colder 'icehouse' world influenced by sea ice and icebergs from the middle Eocene epoch to the present. For the most recent ∼14 Myr, we find sedimentation rates of 1-2 cm per thousand years, in stark contrast to the substantially lower rates proposed in earlier studies; this record of the Neogene reveals cooling of the Arctic that was synchronous with the expansion of Greenland ice (∼3.2 Myr ago) and East Antarctic ice (∼14 Myr ago). We find evidence for the first occurrence of ice-rafted debris in the middle Eocene epoch (∼45 Myr ago), some 35 Myr earlier than previously thought; fresh surface waters were present at ∼49 Myr ago, before the onset of ice-rafted debris. Also, the temperatures of surface waters during the Palaeocene/Eocene thermal maximum (∼55 Myr ago) appear to have been substantially warmer than previously estimated. The revised timing of the earliest Arctic cooling events coincides with those from Antarctica, supporting arguments for bipolar symmetry in climate change. © 2006 Nature Publishing Group

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Human hepatocyte growth factor (hHGF) has been purified 209,000-fold with 18% yield from plasma of a patient with fulminant hepatic failure. The purification involves heat treatment of.plasma, ammonium sulfate precipitation, and chromatography on Affi-Gel Blue, heparin-Sepharose, and hydroxylapatite. Purified hHGF shows several bands with molecular weights between 76,000 and 92,000. Each band shows growthstimulating activity on cultured hepatocytes which is proportional to the intensity of the band. After reduction of the sample with 2-mercaptoethanol, SDS-PAGE yields two chains with molecular weights of 31,500-34,500 and 54,000-65,000. The effect of hHGF on DNA synthesis by hepatocytes is halfmaximal at 3.5 ng/ml. hHGF stimulates proliferation of cultured hepatocytes more effectively than human epidermal growth factor (hEGF) or insulin, and the effect of hHGF is additive or synergistic with the maximal effects of hEGF and insulin. These results suggest that hHGF is a new growth factor which is different from hEGF.

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