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  • 1
    Publication Date: 2014-10-04
    Description: The Procellarum region is a broad area on the nearside of the Moon that is characterized by low elevations, thin crust, and high surface concentrations of the heat-producing elements uranium, thorium, and potassium. The region has been interpreted as an ancient impact basin approximately 3,200 kilometres in diameter, although supporting evidence at the surface would have been largely obscured as a result of the great antiquity and poor preservation of any diagnostic features. Here we use data from the Gravity Recovery and Interior Laboratory (GRAIL) mission to examine the subsurface structure of Procellarum. The Bouguer gravity anomalies and gravity gradients reveal a pattern of narrow linear anomalies that border Procellarum and are interpreted to be the frozen remnants of lava-filled rifts and the underlying feeder dykes that served as the magma plumbing system for much of the nearside mare volcanism. The discontinuous surface structures that were earlier interpreted as remnants of an impact basin rim are shown in GRAIL data to be a part of this continuous set of border structures in a quasi-rectangular pattern with angular intersections, contrary to the expected circular or elliptical shape of an impact basin. The spatial pattern of magmatic-tectonic structures bounding Procellarum is consistent with their formation in response to thermal stresses produced by the differential cooling of the province relative to its surroundings, coupled with magmatic activity driven by the greater-than-average heat flux in the region.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Andrews-Hanna, Jeffrey C -- Besserer, Jonathan -- Head, James W 3rd -- Howett, Carly J A -- Kiefer, Walter S -- Lucey, Paul J -- McGovern, Patrick J -- Melosh, H Jay -- Neumann, Gregory A -- Phillips, Roger J -- Schenk, Paul M -- Smith, David E -- Solomon, Sean C -- Zuber, Maria T -- England -- Nature. 2014 Oct 2;514(7520):68-71. doi: 10.1038/nature13697.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geophysics and Center for Space Resources, Colorado School of Mines, Golden, Colorado 80401, USA. ; Department of Earth and Planetary Sciences, University of California, Santa Cruz, California 95064, USA. ; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island 02912, USA. ; Planetary Science Directorate, Southwest Research Institute, Boulder, Colorado 80302, USA. ; Lunar and Planetary Institute, Houston, Texas 77058, USA. ; Hawaii Institute of Geophysics and Planetology, University of Hawaii, Honolulu, Hawaii 96822, USA. ; Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, USA. ; Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. ; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA. ; 1] Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington DC 20015, USA [2] Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    ISSN: 1573-0646
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 3-Deazaguanine (dezaguanine, USAN; CI-908) is a new antipurine antimetabolite which is entering Phase I studies in the USA. This compound differs from guanine only in the substitution of a carbon for the 3-nitrogen of guanine. Dezaguanine has an unusual spectrum of activity against experimental rodent tumors; its activity against transplantable rodent leukemias is only modest, but it has significant activity against transplantable rodent solid tumors, particularly mammary adenocarcinomas. Mammary adenocarcinoma models against which this compound is active include slow and fast-growing tumors, hormone sensitive and hormone insensitive tumors, and the subrenal capsule implanted human breast cancer xenograft, MX-1. Dezaguanine must be converted to its nucleotides to be active. Dezaguanine nucleotides inhibit synthesis of guanine nucleotides, and can be incorporated into nucleic acids in place of guanine nucleotides; incorporation into DNA may be particularly important in the cytotoxicity of this compound. Addition of certain purines or purine nucleosides can prevent dezaguanine cytotoxicity in vitro. Preclinical studies suggest that dezaguanine does not undergo deamination to 3-deazaxanthine, and is not metabolized by xanthine oxidase. Therefore, this compound may not be subject to metabolic inactivation in vivo, and active metabolites may have a prolonged half-life. This concept is supported by the prolonged half-life of radiolabelled dezaguanine in rats. Finally, dezaguanine can cross the blood-brain barrier. In summary, the novel biochemical and experimental antitumor properties of dezaguanine indicate that this compound could have better activity against some human solid tumors than currently used purine antimetabolites. Preclinical formulation and toxicology studies are now complete, and Phase I human studies are being initiated.
    Type of Medium: Electronic Resource
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