Abstract:
:We have used a semiselective Hahn spin-echo sequence of the form (1331)-tau-(2662)-tau-AQ, delivered by a surface coil to obtain high-resolution 1H NMR spectra from the brains of intact dead rats. This sequence gave suppression of the tissue water resonance by a factor of 80,000 when tau = 68 ms. Delivery of a frequency-selective Dante pulse train to the alpha-CH resonance of lactate at 4.11 ppm, simultaneously with the 2662 refocusing pulse, altered the j-modulation in the spin-coupled beta-CH3 protons. Subtraction of this spectrum from one in which the Dante was ineffective gave an edited spectrum containing only the beta-CH3 resonance of lactate at 1.31 ppm. When the position of the Dante was shifted to 3.78 ppm to selectively invert the alpha-CH protons of alanine, an edited spectrum of alanine was obtained.
journal_name
Proc Natl Acad Sci U S Aauthors
Hetherington HP,Avison MJ,Shulman RGdoi
10.1073/pnas.82.10.3115subject
Has Abstractpub_date
1985-05-01 00:00:00pages
3115-8issue
10eissn
0027-8424issn
1091-6490journal_volume
82pub_type
杂志文章abstract::There is no theoretical limit in using molecular networks to harvest diffusive sun photons on large areas and funnel them onto much smaller areas of highly efficient but also precious energy-converting materials. The most effective concept reported so far is based on a pool of randomly oriented, light-harvesting donor...
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.2019198117
更新日期:2020-12-29 00:00:00
abstract::We have developed a high-efficiency nucleic acid delivery system that uses receptor-mediated endocytosis to carry DNA macromolecules into cells. We accomplished this by conjugating the iron-transport protein transferrin to polycations that bind nucleic acids. Human transferrin, as well as the chicken homologue conalbu...
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.87.9.3410
更新日期:1990-05-01 00:00:00
abstract::Nonsteroidal anti-inflammatory drugs selective for inhibition of COX-2 increase heart failure and elevate blood pressure. The COX-2 gene was floxed and crossed into merCremer mice under the alpha-myosin heavy-chain promoter. Tamoxifen induced selective deletion of COX-2 in cardiomyocytes depressed cardiac output, and ...
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.0805806106
更新日期:2009-05-05 00:00:00
abstract::Antigen.antibody complexes (Ag.Ab) prepared from (125)I-labeled bovine serum albumin and guinea pig anti-albumin were incubated at 37 degrees C for 30 min with normal human serum diluted optimally for binding (1:16) and then with autologous erythrocytes (RBC). After washing, RBC-bearing antigen.antibody.complement com...
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.79.16.5047
更新日期:1982-08-01 00:00:00
abstract::AIDS remains incurable due to the permanent integration of HIV-1 into the host genome, imparting risk of viral reactivation even after antiretroviral therapy. New strategies are needed to ablate the viral genome from latently infected cells, because current methods are too inefficient and prone to adverse off-target e...
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.1405186111
更新日期:2014-08-05 00:00:00
abstract::To investigate protein folding dynamics in terms of compactness, we developed a continuous-flow mixing device to make small-angle x-ray scattering measurements with the time resolution of 160 micros and characterized the radius of gyration (R(g)) of two folding intermediates of cytochrome c (cyt c). The early intermed...
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.012458999
更新日期:2002-02-05 00:00:00
abstract::In his Philosophical Investigations, Wittgenstein famously noted that the formation of semantic representations requires more than a simple combination of verbal and nonverbal features to generate conceptually based similarities and differences. Classical and contemporary neuroscience has tended to focus upon how diff...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 临床试验,杂志文章
doi:10.1073/pnas.0907307107
更新日期:2010-02-09 00:00:00
abstract::Major changes in global rainfall patterns accompanied a northward shift of Earth's thermal equator at the onset of an abrupt climate change 14.6 kya. This northward pull of Earth's wind and rain belts stemmed from disintegration of North Atlantic winter sea ice cover, which steepened the interhemispheric meridional te...
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.1301855110
更新日期:2013-10-15 00:00:00
abstract::A mol of creatine kinase (EC 2.7.3.2), an enzyme with two identical subunits can be titrated very rapidly and stoichiometrically with 2 mol of 2-chloromercuri-4-nitrophenol, an environmentally sensitive chromophoric probe specific for thiols. Chemical modification does not inactivate the enzyme nor can the reaction be...
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.70.10.2858
更新日期:1973-10-01 00:00:00
abstract::CD11c, also known as integrin alpha X, is the most widely used defining marker for dendritic cells (DCs). CD11c can bind complement iC3b and mediate phagocytosis in vitro, for which it is also referred to as complement receptor 4. However, the functions of this prominent marker protein in DCs, especially in vivo, rema...
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.1805542115
更新日期:2018-06-26 00:00:00
abstract::Most mammalian cell types, including endothelial cells, respond to cell swelling by activating a Cl- current termed ICl,swell, but it is not known how the physical stimulus of cell swelling is transferred to the channels underlying ICl,swell. We have investigated the precise relation between cell volume and ICl,swell ...
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.96.9.5298
更新日期:1999-04-27 00:00:00
abstract::Through a process called "bioturbation," burrowing macrofauna have altered the seafloor habitat and modified global carbon cycling since the Cambrian. However, the impact of macrofauna on the community structure of microorganisms is poorly understood. Here, we show that microbial communities across bioturbated, but ge...
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.1917494117
更新日期:2020-07-07 00:00:00
abstract::Nuclear structural changes during fertilization and embryogenesis in mice and in sea urchins have been followed by using antibodies against the nuclear lamins A/C and B and against antigens at the periphery of nuclei and chromosomes. Lamins are found on all pronuclei and nuclei during mouse fertilization, but with a d...
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.82.14.4727
更新日期:1985-07-01 00:00:00
abstract::Micro-RNAs (miR genes) are a large family of highly conserved noncoding genes thought to be involved in temporal and tissue-specific gene regulation. MiRs are transcribed as short hairpin precursors ( approximately 70 nt) and are processed into active 21- to 22-nt RNAs by Dicer, a ribonuclease that recognizes target m...
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.242606799
更新日期:2002-11-26 00:00:00
abstract::Normal rat kidney cells infected with a temperature-sensitive mutant (LA23) of Rous sarcoma virus exhibit the transformed phenotype when grown at 33 degrees and the normal phenotype at 39 degrees. We have previously shown [Ash, J.F., Vogt, P.K. & Singer, S.J. (1976) Proc. Natl. Acad. Sci. USA 73, 3603-3607] that the 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.75.10.5015
更新日期:1978-10-01 00:00:00
abstract::The issue of protein dynamics and its implications in the biological function of proteins are arousing greater and greater interest in different fields of molecular biology. In cryo-electron tomography experiments one may take several snapshots of a given biological macromolecule. In principle, a large enough collecti...
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.0400119101
更新日期:2004-04-27 00:00:00
abstract::Environmental cues are transmitted to the interior of the cell via a complex network of signaling hubs. Receptor tyrosine kinases (RTKs) and trimeric G proteins are two such major signaling hubs in eukaryotes. Conventionally, canonical signal transduction via trimeric G proteins is thought to be triggered exclusively ...
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.1420140112
更新日期:2015-03-03 00:00:00
abstract::The modern Old World Monkeys (Superfamily Cercopithecoidea, Family Cercopithecidae) can be traced back into the late Miocene, but their origin and subsequent diversification is obscured by the scarcity of terrestrial fossil sites in Africa between 15 and 6 Ma. Here, we document the presence of cercopithecids at 12.5 M...
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.1213691110
更新日期:2013-04-09 00:00:00
abstract::Theoretical distributions of genetic distance between reproductively isolated taxa are derived by means of computer simulation, taking into account mutation and random genetic drift. The distributions obtained are in good agreement with the observed distributions of interracial and interspecific genetic distances for ...
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.72.7.2758
更新日期:1975-07-01 00:00:00
abstract::Genomic analyses of patients with congenital heart disease (CHD) have identified significant contribution from mutations affecting cilia genes and chromatin remodeling genes; however, the mechanism(s) connecting chromatin remodeling to CHD is unknown. Histone H2B monoubiquitination (H2Bub1) is catalyzed by the RNF20 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.1808341116
更新日期:2019-07-09 00:00:00
abstract::We have cloned an additional member (GC-D) of the membrane receptor guanylyl cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2] family that is specifically expressed in a subpopulation of olfactory sensory neurons. The extracellular, putative ligand-binding domain of the olfactory cyclase is similar in primary ...
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.92.8.3571
更新日期:1995-04-11 00:00:00
abstract::In a previous study, we found that human neural stem cells (HNSCs) exposed to high concentrations of secreted amyloid-precursor protein (sAPP) in vitro differentiated into mainly astrocytes, suggesting that pathological alterations in APP processing during neurodegenerative conditions such as Alzheimer's disease (AD) ...
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.0705346104
更新日期:2007-07-24 00:00:00
abstract::The trinucleotide CCA sequence is present at the 3' terminus of all mature tRNAs. Despite this high degree of conservation, we have been able to prepare in vitro transcripts of Escherichia coli tRNA(Val) with altered 3' termini that are readily aminoacylated and can function in polypeptide synthesis. Replacement of th...
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.91.22.10389
更新日期:1994-10-25 00:00:00
abstract::We show in climate model experiments that large-scale afforestation in northern mid-latitudes warms the Northern Hemisphere and alters global circulation patterns. An expansion of dark forests increases the absorption of solar energy and increases surface temperature, particularly in regions where the land surface is ...
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.1116706108
更新日期:2012-01-17 00:00:00
abstract::X-chromosome inactivation (XCI) is initiated by the long noncoding RNA Xist, which coats the inactive X (Xi) and targets Polycomb repressive complex 2 (PRC2) in cis. Epigenomic analyses have provided significant insight into Xist binding patterns and chromatin organization of the Xi. However, such epigenomic analyses ...
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.1503690112
更新日期:2015-08-04 00:00:00
abstract::Phosphoinositides are essential lipid regulators of trafficking and signaling pathways of all eukaryotic cells. Phosphatidylinositol 4-phosphate (PtdIns4P) is an intermediate in the synthesis of several important phosphoinositide species but also serves as a regulatory molecule in its own right. Phosphatidylinositol 4...
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.1000157107
更新日期:2010-05-04 00:00:00
abstract::Elucidating the mechanism of folding of polynucleotides depends on accurate estimates of free energy surfaces and a quantitative description of the kinetics of structure formation. Here, the kinetics of hairpin formation in single-stranded DNA are measured after a laser temperature jump. The kinetics are modeled as co...
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.131477798
更新日期:2001-07-03 00:00:00
abstract::Fatty liver disease (FLD) is a disorder in which accumulation of triglycerides (TGs) in the liver can lead to inflammation, fibrosis, and cirrhosis. Previously, we identified a variant (I148M) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) that is strongly associated with FLD, but the mechanistic b...
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.1901974116
更新日期:2019-05-07 00:00:00
abstract::Recent epidemiological studies indicate beneficial effects of moderate ethanol consumption in ischemic heart disease. Most studies, however, focus on the effect of long-term consumption of ethanol. In this study, we determined whether brief exposure to ethanol immediately before ischemia also produces cardioprotection...
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.96.22.12784
更新日期:1999-10-26 00:00:00
abstract::The Escherichia coli chaperonins GroEL and GroES facilitate the refolding of polypeptide chains in an ATP hydrolysis-dependent reaction. The elementary steps in the binding and release of polypeptide substrates to GroEL were investigated in surface plasmon resonance studies to measure the rates of binding and dissocia...
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.93.5.1977
更新日期:1996-03-05 00:00:00