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981.
Antibodies to the core protein of lymphadenopathy-associated virus (LAV) in patients with AIDS 总被引:16,自引:0,他引:16
V S Kalyanaraman C D Cabradilla J P Getchell R Narayanan E H Braff J C Chermann F Barré-Sinoussi L Montagnier T J Spira J Kaplan 《Science (New York, N.Y.)》1984,225(4659):321-323
Lymphadenopathy-associated virus ( LAV ), a human T- lymphotrophic retrovirus isolated from a homosexual man with lymphadenopathy, has been causally associated with acquired immunodeficiency syndrome (AIDS). A sensitive and specific radioimmunoprecipitation test was developed for the detection of antibodies to the major core protein of LAV , p25 (molecular weight 25,000). Antibody to LAV p25 was found in the serum of 51 of 125 AIDS patients, 81 of 113 patients with lymphadenopathy syndrome, 0 of 70 workers at the Centers for Disease Control (some of whom had handled specimens from AIDS patients), and 0 of 189 random blood donors. Of a group of 100 homosexual men from San Francisco whose serum was obtained in 1978, only one had antibody to LAV p25; in contrast, of a group of 50 homosexual men in the same community whose serum was obtained in 1984, 12 had antibodies to LAV p25. 相似文献
982.
In vitro binding studies have demonstrated the existence of multiple opiate receptor types. An additional site in the rat brain (termed the lambda site) is distinct from the established types by its selectivity for 4,5-epoxymorphinans (such as naloxone and morphine). While the lambda site displays a high affinity for naloxone in vivo and in vitro in fresh brain membrane homogenates, these sites rapidly convert in vitro to a state of low affinity. The regional distribution of the lambda site in the brain is strikingly different from that of the classic opiate receptor types. 相似文献
983.
Piro L Garmire G Garcia M Stratta G Costa E Feroci M Mészáros P Vietri M Bradt H Frail D Frontera F Halpern J Heise J Hurley K Kawai N Kippen RM Marshall F Murakami T Sokolov VV Takeshima T Yoshida A 《Science (New York, N.Y.)》2000,290(5493):955-958
We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha) line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron approximately 0.01 of the mass of the sun at a velocity approximately 0.1 of the speed of light, probably by a supernova explosion. 相似文献
984.
McPherson JP Lemmers B Chahwan R Pamidi A Migon E Matysiak-Zablocki E Moynahan ME Essers J Hanada K Poonepalli A Sanchez-Sweatman O Khokha R Kanaar R Jasin M Hande MP Hakem R 《Science (New York, N.Y.)》2004,304(5678):1822-1826
Mus81-Eme1 endonuclease has been implicated in the rescue of stalled replication forks and the resolution of meiotic recombination intermediates in yeast. We used gene targeting to study the physiological requirements of Mus81 in mammals. Mus81-/- mice are viable and fertile, which indicates that mammalian Mus81 is not essential for recombination processes associated with meiosis. Mus81-deficient mice and cells were hypersensitive to the DNA cross-linking agent mitomycin C but not to gamma-irradiation. Remarkably, both homozygous Mus81-/- and heterozygous Mus81+/- mice exhibited a similar susceptibility to spontaneous chromosomal damage and a profound and equivalent predisposition to lymphomas and other cancers. These studies demonstrate a critical role for the proper biallelic expression of the mammalian Mus81 in the maintenance of genomic integrity and tumor suppression. 相似文献
985.
986.
Pascual JI Méndez J Gómez-Herrero J Baró AM Garcia N Landman U Luedtke WD Bogachek EN Cheng HP 《Science (New York, N.Y.)》1995,267(5205):1793-1795
Material structures of reduced dimensions exhibit electrical and mechanical properties different from those in the bulk. Measurements of room-temperature electronic transport in pulled metallic nanowires are presented, demonstrating that the conductance characteristics depend on the length, lateral dimensions, state and degree of disorder, and elongation mechanism of the wire. Conductance during the elongation of short wires (length l approximately 50 angstroms) exhibits periodic quantization steps with characteristic dips, correlating with the order-disorder states of layers of atoms in the wire predicted by molecular dynamics simulations. The resistance R of wires as long as l approximately 400 angstroms exhibits localization characteristics with In R(l) approximately l(2). 相似文献
987.
Cariolle D Amodei M Déqué M Mahfouf JF Simon P Teyssédre H 《Science (New York, N.Y.)》1993,261(5126):1313-1316
The quasi-biennial oscillation (QBO) is a free atmospheric mode that affects the equatorial lower stratosphere. With a quasi-regular frequency, the mean equatorial zonal wind alternates from easterly to westerly regimes. This oscillation is zonally symmetric about the equator, has its largest amplitude in the latitudinal band from 20 degrees S to 20 degrees N, and has a mean period of about 27 months. The QBO appears to originate in the momentum deposition produced by the damping in the stratosphere of equatorial waves excited by diabatic thermal processes in the troposphere. The results of three 10-year simulations obtained with three general circulation models are reported, all of which show the development in the stratosphere of a QBO signal with a period and a spatial propagating structure that are in good agreement with observations without any ad hoc parameterization of equatorial wave forcing. Although the amplitude of the oscillation in the simulations is still less than the observed value, the result is promising for the development of global climate models. 相似文献
988.
te Welscher P Zuniga A Kuijper S Drenth T Goedemans HJ Meijlink F Zeller R 《Science (New York, N.Y.)》2002,298(5594):827-830
Distal limb development and specification of digit identities in tetrapods are under the control of a mesenchymal organizer called the polarizing region. Sonic Hedgehog (SHH) is the morphogenetic signal produced by the polarizing region in the posterior limb bud. Ectopic anterior SHH signaling induces digit duplications and has been suspected as a major cause underlying congenital malformations that result in digit polydactyly. Here, we report that the polydactyly of Gli3-deficient mice arises independently of SHH signaling. Disruption of one or both Gli3 alleles in mouse embryos lacking Shh progressively restores limb distal development and digit formation. Our genetic analysis indicates that SHH signaling counteracts GLI3-mediated repression of key regulator genes, cell survival, and distal progression of limb bud development. 相似文献
989.
Mészáros P 《Science (New York, N.Y.)》2001,291(5501):79-84
Gamma-ray bursts (GRBs) are sudden, intense flashes of gamma rays that, for a few blinding seconds, light up in an otherwise fairly dark gamma-ray sky. They are detected at the rate of about once a day, and while they are on, they outshine every other gamma-ray source in the sky, including the sun. Major advances have been made in the last 3 or 4 years, including the discovery of slowly fading x-ray, optical, and radio afterglows of GRBs, the identification of host galaxies at cosmological distances, and evidence showing that many GRBs are associated with star-forming regions and possibly supernovae. Progress has been made in understanding how the GRB and afterglow radiation arises in terms of a relativistic fireball shock model. These advances have opened new vistas and questions on the nature of the central engine, the identity of their progenitors, the effects of the environment, and their possible gravitational wave, cosmic ray, and neutrino luminosity. The debates on these issues indicate that GRBs remain among the most mysterious puzzles in astrophysics. 相似文献
990.
Zepik H Shavit E Tang M Jensen TR Kjaer K Bolbach G Leiserowitz L Weissbuch I Lahav M 《Science (New York, N.Y.)》2002,295(5558):1266-1269
Differences in the two-dimensional packing arrangements of racemic and enantiomeric crystalline self-assemblies on the water surface of amphiphilic activated analogs of lysine and glutamic acid have been used to prepare oligopeptides of homochiral sequence and oligopeptides of single handedness from chiral nonracemic mixtures. The crystalline structures on the water surface were determined by grazing incidence x-ray diffraction and the diastereomeric composition of the oligopeptides by matrix-assisted laser desorption time-of-flight mass spectrometry with enantio-labeling. These results suggest that reactivity of ordered clusters at interfaces might have played a role in the generation of early homochiral biopolymers. 相似文献