Abstract:
:Many studies have reported age-related changes in immune responses that could be due to alterations in lymphoid cell numbers or functions. Here we report the results of studies using immunofluorescent staining and in vitro assays of cellular function to compare the expression of cell surface antigens on lymphocytes from mice up to 2 years of age. No significant changes were observed in the frequencies of spleen cells bearing class I or class II major histocompatibility complex (MHC) antigens, surface immunoglobulin, or Thy-1, Ly-1, Ly-2, or L3T4 antigens. However, the densities (per cell) of both class I and class II MHC antigens were increased significantly on cells from aged as compared to young mice, whereas the densities of the other cell surface antigens studied were unchanged or slightly decreased. The increased levels of MHC antigen expression in old relative to young mice were shown to be functionally significant regarding immunological stimulation. These data suggest that T-cell clones silent in young individuals may be activated in comparable situations in older animals, leading to immunological alterations perhaps including increased autoreactivity.
journal_name
Proc Natl Acad Sci U S Aauthors
Sidman CL,Luther EA,Marshall JD,Nguyen KA,Roopenian DC,Worthen SMdoi
10.1073/pnas.84.21.7624subject
Has Abstractpub_date
1987-11-01 00:00:00pages
7624-8issue
21eissn
0027-8424issn
1091-6490journal_volume
84pub_type
杂志文章abstract::Fatty acylation of cysteine residues provides spatial and temporal control of protein function in cells and regulates important biological pathways in eukaryotes. Although recent methods have improved the detection and proteomic analysis of cysteine fatty (S-fatty) acylated proteins, understanding how specific sites a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1602244113
更新日期:2016-04-19 00:00:00
abstract::Metallic nanoscale structures are capable of supporting surface plasmon polaritons (SPPs), propagating collective electron oscillations with tight spatial confinement at the metal surface. SPPs represent one of the most promising structures to beat the diffraction limit imposed by conventional dielectric optics. Ag na...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0902064106
更新日期:2009-12-15 00:00:00
abstract::This article extends our previous quantitative analysis of the relationship between the dynamics of the primary structure of DNA and mutagenesis associated with single-strand lesions to an analysis of the production and processing of endogenous double-strand breaks (EDSBs) and to their implications for oncogenesis. We...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2135498100
更新日期:2003-10-28 00:00:00
abstract::In 1950, John Nash contributed a remarkable one-page PNAS article that defined and characterized a notion of equilibrium for n- person games. This notion, now called the "Nash equilibrium," has been widely applied and adapted in economics and other behavioral sciences. Indeed, game theory, with the Nash equilibrium as...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0308738101
更新日期:2004-03-23 00:00:00
abstract::Protein carboxymethylase, an enzyme capable of methylating proteins and polypeptides, was purified from bovine pituitary. The anterior pituitary hormones, luteinizing hormone, follicle-stimulating hormone, adrenocorticotropic hormone, growth hormone, thyroid-stimulating hormone, and prolactin, were found to be substra...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.71.5.1701
更新日期:1974-05-01 00:00:00
abstract::Site-specific recombination is responsible for a broad range of biological phenomena, including DNA inversion, resolution of transposition intermediates, and the integration and excision of bacteriophage genomes. Integration of mycobacteriophage L5 is catalyzed by a phage-encoded integrase with recombination occurring...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.140014297
更新日期:2000-07-05 00:00:00
abstract::Inward rectifying potassium (Kir) channels participate in regulating potassium concentration (K(+)) in the central nervous system (CNS), including in the retina. We explored the contribution of Kir channels to retinal function by delivering Kir antibodies (Kir-Abs) into the rat eye in vivo to interrupt channel activit...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0913472107
更新日期:2010-07-13 00:00:00
abstract::Mycobacterium marinum, a natural pathogen of fish and frogs and an occasional pathogen of humans, is capable of inducing actin tail formation within the cytoplasm of macrophages, leading to actin-based motility and intercellular spread. Actin tail formation by M. marinum is markedly reduced in macrophages deficient in...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0504663102
更新日期:2005-10-11 00:00:00
abstract::Increasing concentrations of estradiol (E2) ranging from 0.01 to 10 nM were found to inhibit partially but significantly the lactogenic effect of ovine prolactin (oPRL) on alpha-lactalbumin production in primate mammary tissues maintained in organ culture for 9 days. E2 at 10 nM inhibited by 38% (mean) PRL-stimulated ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.80.13.4144
更新日期:1983-07-01 00:00:00
abstract::It is well established that pregnancy early in life reduces the risk of breast cancer in women and that this effect is universal. This phenomenon of parity protection against mammary cancer is also observed in rodents. Earlier studies have demonstrated that short-term administration of estradiol (E) in combination wit...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.201393798
更新日期:2001-09-25 00:00:00
abstract::Whereas 234(92)U142 and other actinon nuclei have ground-state bands that indicate that each nucleus consists of a sphere and a single revolving cluster with constant composition and with only a steady increase in the moment of inertia with increase in J, the angular-momentum quantum number, many of the lanthanon grou...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.3.820
更新日期:1991-02-01 00:00:00
abstract::The hammerhead ribozyme, as engineered by J. Haseloff and W. L. Gerlach [(1988) Nature (London) 334, 585-591], is an RNA molecule containing two regions of conserved nucleotides, a double helix, called helix II, which connects the two conserved regions, and flanking arms of variable sequence, which hybridize the riboz...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.13.5710
更新日期:1992-07-01 00:00:00
abstract::Multiple epidemic diseases have been designated as emerging or reemerging because the numbers of clinical cases have increased. Emerging diseases are often suspected to be driven by increased virulence or fitness, possibly associated with the gain of novel genes or mutations. However, the time period over which humans...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1411012111
更新日期:2014-08-19 00:00:00
abstract::The positive transcription elongation factor b (P-TEFb) is involved in physiological and pathological events including inflammation, cancer, AIDS, and cardiac hypertrophy. The balance between its active and inactive form is tightly controlled to ensure cellular integrity. We report that the transcriptional repressor C...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1220136110
更新日期:2013-07-30 00:00:00
abstract::GB virus B (GBV-B), which infects tamarins, is the virus most closely related to hepatitis C virus (HCV). HCV has a protein (p7) that is believed to form an ion channel. It is critical for viability. In vitro studies suggest that GBV-B has an analogous but larger protein (p13). We found that substitutions of the -1 an...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0511297103
更新日期:2006-02-28 00:00:00
abstract::Chronic sleep deprivation perturbs the circadian clock and increases susceptibility to diseases such as diabetes, obesity, and cancer. Increased inflammation is one of the common underlying mechanisms of these diseases, thus raising a hypothesis that circadian-oscillator components may regulate immune response. Here w...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1209965109
更新日期:2012-07-31 00:00:00
abstract::Tobacco mosaic virus (TMV) was reconstituted from the RNA of a common strain (OM) and the protein of a watermelon strain of cucumber green mottle mosaic virus (CGMMV-W), which is a member of the tobamovirus group. In 0.25 M phosphate buffer at 25 degrees C, CGMMV-W protein existed mainly as 21S aggregates. When this p...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.19.5833
更新日期:1982-10-01 00:00:00
abstract::Male relationships in most species of mammals generally are characterized by intense intrasexual competition, with little bonding among unrelated individuals. In contrast, human societies are characterized by high levels of cooperation and strong bonds among both related and unrelated males. The emergence of cooperati...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1405811111
更新日期:2014-10-14 00:00:00
abstract::Asexual freshwater planarians reproduce by tearing themselves into two pieces by a process called binary fission. The resulting head and tail pieces regenerate within about a week, forming two new worms. Understanding this process of ripping oneself into two parts poses a challenging biomechanical problem. Because pla...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1700762114
更新日期:2017-10-10 00:00:00
abstract::Previously it was shown that yeast ADA2 protein is necessary for the full activity of some activation domains, such as VP16 and GCN4, in vivo and in vitro. These results suggest that ADA2 protein functions as a transcriptional coactivator or adaptor that bridges the interaction between certain acidic activation domain...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.24.11665
更新日期:1994-11-22 00:00:00
abstract::Cognitive flexibility depends on a fast neural learning mechanism for enhancing momentary relevant over irrelevant information. A possible neural mechanism realizing this enhancement uses fast spiking interneurons (FSIs) in the striatum to train striatal projection neurons to gate relevant and suppress distracting cor...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2001348117
更新日期:2020-07-28 00:00:00
abstract::Sepiapterin reductase (7,8-dihydrobiopterin: NADP+ oxidoreductase, EC 1.1.1.153) catalyzes the terminal step in the biosynthetic pathway for tetrahydrobiopterin, the cofactor necessary for aromatic amino acid hydroxylation. We report here the isolation of a cDNA clone for rat liver sepiapterin reductase. The cDNA has ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.16.6436
更新日期:1990-08-01 00:00:00
abstract::Chromatin boundaries or insulators modulate enhancer-promoter interactions in complex genetic loci. However, the mechanism underlying insulator activity is not known. Previous studies showed that the activity of the Drosophila suHw insulator is abolished by the tandem arrangement (pairing) of the insulator elements, s...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0830190100
更新日期:2003-04-29 00:00:00
abstract::The cytoskeleton provides structural integrity to cells and serves as a key component in mechanotransduction. Tensins are thought to provide a force-bearing linkage between integrins and the actin cytoskeleton; yet, direct evidence of tensin's role in mechanotransduction is lacking. We here report that local force app...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1911865116
更新日期:2019-10-01 00:00:00
abstract::Dominant mutations in the maize homeobox gene knotted1 (kn1) act nonautonomously during maize leaf development, indicating that Kn1 is involved in the generation or transmission of a developmental signal that passes from the inner layers of the leaf to epidermal cells. We previously found that this nonautonomous activ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.052484099
更新日期:2002-03-19 00:00:00
abstract::A stable complex between pentaammineruthenium(III) and histidine-33 in horse heart ferricytochrome c is formed in the reaction between aquopentaammineruthenium(II) and the protein at pH 7. HPLC of the tryptic hydrolysate of the modified protein was employed to identify the pentaammineruthenium binding site. Spectrosco...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.22.7052
更新日期:1982-11-01 00:00:00
abstract::Plant soil specialists contribute greatly to global diversity; however, the ecoevolutionary forces responsible for generating this diversity are poorly understood. We integrate molecular phylogenies with descriptive and experimental ecological data, creating a powerful framework with which to elucidate forces driving ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1409242111
更新日期:2014-10-21 00:00:00
abstract::Fibronectin mediates the adhesion of cells to collagen by first binding to the collagen substrate, followed by attachment of the cells to the fibronectin-collagen complex. Bovine brain gangliosides were found to block fibronectin-mediated cell adhesion to collagen in a concentration-dependent manner. The gangliosides ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.76.7.3367
更新日期:1979-07-01 00:00:00
abstract::Nanophthalmos is a rare disorder of eye development characterized by extreme hyperopia (farsightedness), with refractive error in the range of +8.00 to +25.00 diopters. Because the cornea and lens are normal in size and shape, hyperopia occurs because insufficient growth along the visual axis places these lensing comp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0501451102
更新日期:2005-07-05 00:00:00
abstract::Shigella sonnei is a human-adapted pathogen that is emerging globally as the dominant agent of bacterial dysentery. To investigate local establishment, we sequenced the genomes of 263 Vietnamese S. sonnei isolated over 15 y. Our data show that S. sonnei was introduced into Vietnam in the 1980s and has undergone locali...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1308632110
更新日期:2013-10-22 00:00:00