排序方式: 共有20条查询结果,搜索用时 46 毫秒
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Ambati BK Nozaki M Singh N Takeda A Jani PD Suthar T Albuquerque RJ Richter E Sakurai E Newcomb MT Kleinman ME Caldwell RB Lin Q Ogura Y Orecchia A Samuelson DA Agnew DW St Leger J Green WR Mahasreshti PJ Curiel DT Kwan D Marsh H Ikeda S Leiper LJ Collinson JM Bogdanovich S Khurana TS Shibuya M Baldwin ME Ferrara N Gerber HP De Falco S Witta J Baffi JZ Raisler BJ Ambati J 《Nature》2006,443(7114):993-997
Corneal avascularity-the absence of blood vessels in the cornea-is required for optical clarity and optimal vision, and has led to the cornea being widely used for validating pro- and anti-angiogenic therapeutic strategies for many disorders. But the molecular underpinnings of the avascular phenotype have until now remained obscure and are all the more remarkable given the presence in the cornea of vascular endothelial growth factor (VEGF)-A, a potent stimulator of angiogenesis, and the proximity of the cornea to vascularized tissues. Here we show that the cornea expresses soluble VEGF receptor-1 (sVEGFR-1; also known as sflt-1) and that suppression of this endogenous VEGF-A trap by neutralizing antibodies, RNA interference or Cre-lox-mediated gene disruption abolishes corneal avascularity in mice. The spontaneously vascularized corneas of corn1 and Pax6+/- mice and Pax6+/- patients with aniridia are deficient in sflt-1, and recombinant sflt-1 administration restores corneal avascularity in corn1 and Pax6+/- mice. Manatees, the only known creatures uniformly to have vascularized corneas, do not express sflt-1, whereas the avascular corneas of dugongs, also members of the order Sirenia, elephants, the closest extant terrestrial phylogenetic relatives of manatees, and other marine mammals (dolphins and whales) contain sflt-1, indicating that it has a crucial, evolutionarily conserved role. The recognition that sflt-1 is essential for preserving the avascular ambit of the cornea can rationally guide its use as a platform for angiogenic modulators, supports its use in treating neovascular diseases, and might provide insight into the immunological privilege of the cornea. 相似文献
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The structural basis for an essential subunit interaction in influenza virus RNA polymerase 总被引:1,自引:0,他引:1
Obayashi E Yoshida H Kawai F Shibayama N Kawaguchi A Nagata K Tame JR Park SY 《Nature》2008,454(7208):1127-1131
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Compact lasers that can produce a range of beam patterns are important for progress in several areas, including the improvement of optical tweezers, ultra-high-density optical memory and microfluidics. Here we engineer photonic crystals to generate semiconductor lasers that produce a range of beam patterns while maintaining stable single-mode oscillation. Our results could contribute to the realization of compact lasers that are capable of producing diverse beam patterns on demand. 相似文献
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Akihiko NAGATA Takeo OKU Kenji KIKUCHI Atsushi SUZUKI Yasuhiro YAMASAKI Eiji OSAWA 《自然科学进展(英文版)》2010,20(1):38-42
Nanodiamond-based solar cells were fa bricated and the photovoltaic properties were investigated. Fullerene (C60) and fullerenol (C60(OH)10-12) were used as n-type semiconductors, and diamond nan oparticles and metal phthalocyanine derivative were
used as p-type semiconductors. The nanostructures of the solar cel ls were investigated by transmission electron microscopy and X-ray diffracometry, and the electronic property was discussed. 相似文献
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Seismological observations have revealed the existence of low-velocity and high-attenuation zones above the discontinuity at 410 km depth, at the base of the Earth's upper mantle. It has been suggested that a small amount of melt could be responsible for such anomalies. The density of silicate melt under dry conditions has been measured at high pressure and found to be denser than the surrounding solid, thereby allowing the melt to remain at depth. But no experimental investigation of the density of hydrous melt has yet been carried out. Here we present data constraining the density of hydrous basaltic melt under pressure to examine the stability of melt above the 410-km discontinuity. We infer that hydrous magma formed by partial melting above the 410-km discontinuity may indeed be gravitationally stable, thereby supporting the idea that low-velocity or high-attentuation regions just above the mantle transition zone may result from the presence of melt. 相似文献
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Isshiki M Irifune T Hirose K Ono S Ohishi Y Watanuki T Nishibori E Takata M Sakata M 《Nature》2004,427(6969):60-63
Carbonates are important constituents of marine sediments and play a fundamental role in the recycling of carbon into the Earth's deep interior via subduction of oceanic crust and sediments. Study of the stability of carbonates under high pressure and temperature is thus important for modelling the carbon budget in the entire Earth system. Such studies, however, have rarely been performed under appropriate lower-mantle conditions and no experimental data exist at pressures greater than 80 GPa (refs 3-6). Here we report an in situ X-ray diffraction study of the stability of magnesite (MgCO(3)), which is the major component of subducted carbonates, at pressure and temperature conditions approaching those of the core-mantle boundary. We found that magnesite transforms to an unknown form at pressures above approximately 115 GPa and temperatures of 2,100-2,200 K (depths of approximately 2,600 km) without any dissociation, suggesting that magnesite and its high-pressure form may be the major hosts for carbon throughout most parts of the Earth's lower mantle. 相似文献
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