Abstract:
:Purified fractions of human apotransferrin, monoferric transferrins with iron on the acid-labile binding site and on the acid-stable binding site, and diferric transferrin have been prepared. The iron loading and unloading behavior of these preparations has been examined by isoelectric focusing. Iron release from the two monoferric transferrin preparations to human reticulocytes was of similar magnitude. In a mixture containing equal amounts of diferic and monoferric iron, approximately 4 times the amount of iron delivered by the monoferric species was delivered by the diferric species. Iron loading of transferrin in vitro showed a random distribution between monoferric and diferric transferrin. Among the monoferric transferrins, loading of the acid-labile binding sites was greater than that of the acid-stable binding sites. In vivo iron distribution in normal subjects, as evaluated by in vitro-added 50Fe, gave similar results. Absorption of a large dose of orally administered iron in iron-deficient subjects resulted in a somewhat greater amount of diferric transferrin at low saturation and a somewhat smaller amount of diferric transferrin at higher saturations than would have been anticipated by random loading. These data would indicate that in the human, iron loading of transferrin may be considered essentially random. Unloading from the two monoferric transferrin species is of similar magnitude but far less than that delivered by diferric transferrin.
journal_name
Proc Natl Acad Sci U S Aauthors
Huebers H,Josephson B,Huebers E,Csiba E,Finch Cdoi
10.1073/pnas.78.4.2572subject
Has Abstractpub_date
1981-04-01 00:00:00pages
2572-6issue
4eissn
0027-8424issn
1091-6490journal_volume
78pub_type
杂志文章abstract::The onset of autoimmunity in experimental rodent models and patients frequently correlates with a lymphopenic state. In this condition, the immune system has evolved compensatory homeostatic mechanisms that induce quiescent naive T cells to proliferate and differentiate into memory-like lymphocytes even in the apparen...
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.0807743105
更新日期:2008-12-09 00:00:00
abstract::The activation of plant defensive genes in leaves of tomato plants in response to herbivore damage or mechanical wounding is mediated by a mobile 18-amino acid polypeptide signal called systemin. Systemin is derived from a larger, 200-amino acid precursor called prosystemin, similar to polypeptide hormones and soluble...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章,评审
doi:10.1073/pnas.93.22.12053
更新日期:1996-10-29 00:00:00
abstract::We document male-biased sex ratios among U.S.-born children of Chinese, Korean, and Asian Indian parents in the 2000 U.S. Census. This male bias is particularly evident for third children: If there was no previous son, sons outnumbered daughters by 50%. By contrast, the sex ratios of eldest and younger children with 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.0800703105
更新日期:2008-04-15 00:00:00
abstract::The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) is a P-type ATPase that transports Ca2+ from the cytosol into the sarco(endo)plasmic reticulum (SR/ER) lumen, driven by ATP. This primary transport activity depends on tight coupling between movements of the transmembrane helices forming the two Ca2+-binding 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.2014896117
更新日期:2020-12-08 00:00:00
abstract::The orphan nuclear receptor Nur77/N10 has recently been demonstrated to be involved in apoptosis of T cell hybridomas. We report here that chronic expression of Nur77/N10 in thymocytes of transgenic mice results in a dramatic reduction of CD4+CD8+ double-positive as well as CD4+CD8- and CD4-CD8+ single-positive cell 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.93.11.5533
更新日期:1996-05-28 00:00:00
abstract::The electron spin resonance spectrum of the triplet excited state of Rhodopseudomonas spheroides R-26 reaction centers has been studied after excitation with the polarized narrow-bandwidth output of a tunable dye laser from 520 to 670 nm. A theory is developed relating experimental observables to the angles between 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.76.11.5636
更新日期:1979-11-01 00:00:00
abstract::The nucleic acid sequence of the 3' region of human T-cell leukemia virus type II (HTLV-II) proviral DNA was determined using a HTLV-II proviral clone that could be recovered as infectious, transforming virus. The sequence data indicate a region of unknown function of approximately equal to 1.6 kilobase pairs in the 3...
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.81.21.6657
更新日期:1984-11-01 00:00:00
abstract::After the start of transcription, the 5' ends of eukaryotic mRNA molecules are modified by the addition of a guanylyl residue to form a cap structure, G(5')ppp(5')N. The guanylyltransferase (GTP:mRNA guanylyltransferase, EC 2.7.7.50) reaction responsible for cap formation usually proceeds via a covalent enzyme-GMP int...
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.92.2.507
更新日期:1995-01-17 00:00:00
abstract::Patent ductus arteriosus (PDA) is a common congenital heart disease that results when the ductus arteriosus, a muscular artery, fails to remodel and close after birth. A syndromic form of this disorder, Char syndrome, is caused by mutation in TFAP2B, the gene encoding a neural crest-derived transcription factor. Estab...
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.0409852102
更新日期:2005-02-22 00:00:00
abstract::The cytokine IFN-γ is a critical regulator of immune system development and function. Almost all leukocytes express the receptor for IFN-γ, yet each cell type elicits a different response to this cytokine. Cell type-specific effects of IFN-γ make it difficult to predict the outcomes of the systemic IFN-γ blockade 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.1804556115
更新日期:2018-11-06 00:00:00
abstract::A recent study showed that limited trypsin treatment of liposomes containing purified Electrophorus electricus sodium channels activates a sodium radiotracer flux. We now report that similarly treated sodium channels show voltage-gated, tetrodotoxin-sensitive and highly sodium-selective single-channel currents when 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.86.23.9592
更新日期:1989-12-01 00:00:00
abstract::Seasonal cycles govern life on earth, from setting the time for the mating season to influencing migrations and governing physiological conditions like hibernation. The effect of such changing conditions on behavior is well-appreciated, but their impact on the brain remains virtually unknown. We investigate long-term ...
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.1922888117
更新日期:2020-12-15 00:00:00
abstract::Liver fibrosis interferes with normal liver function and facilitates hepatocellular carcinoma (HCC) development, representing a major threat to human health. Here, we present a comprehensive perspective of microRNA (miRNA) function on targeting the fibrotic microenvironment. Starting from a murine HCC model, we identi...
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.1909145117
更新日期:2020-01-07 00:00:00
abstract::Dark-cycle, night administration of the pineal hormone melatonin in drinking water to aging mice (15 months of age) prolongs survival of BALB/c females from 23.8 to 28.1 months and preserves aspects of their youthful state. Similar results were seen in New Zealand Black females beginning at 5 months and C57BL/6 males ...
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.91.2.787
更新日期:1994-01-18 00:00:00
abstract::The mechanistic target of rapamycin complex 1 (mTORC1) growth pathway detects nutrients through a variety of sensors and regulators that converge on the Rag GTPases, which form heterodimers consisting of RagA or RagB tightly bound to RagC or RagD and control the subcellular localization of mTORC1. The Rag heterodimer ...
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.1811727115
更新日期:2018-09-18 00:00:00
abstract::It is well documented that human modification of the hydrological cycle has profoundly affected the flow of liquid water across the Earth's land surface. Alteration of water vapor flows through land-use changes has received comparatively less attention, despite compelling evidence that such alteration can influence 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.0500208102
更新日期:2005-05-24 00:00:00
abstract::After more than a decade of experiments generating and studying the physics of quantized vortices in atomic gas Bose-Einstein condensates, research is beginning to focus on the roles of vortices in quantum turbulence, as well as other measures of quantum turbulence in atomic condensates. Such research directions have ...
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.1312737110
更新日期:2014-03-25 00:00:00
abstract::Signaling through Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) is central to the responses to the majority of cytokines and some growth factors, including the interferons (IFNs) and the IL-6 family of cytokines. The biological responses to stimulation through the widely distribut...
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.122236099
更新日期:2002-06-11 00:00:00
abstract::Unit electrical activity was recorded from single neurons in the isolated lumbo-sacral spinal cord of 14- to 19-day chick embryos, in situ. Spinal cord transection was combined with transection of all lumbo-sacral dorsal roots. The spontaneous discharge of cells is confined, for the most part, to the lower two thirds ...
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.66.1.40
更新日期:1970-05-01 00:00:00
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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.96.26.14783
更新日期:1999-12-21 00:00:00
abstract::In recent years, advertisers and magazine editors have been widely criticized for taking digital photo retouching to an extreme. Impossibly thin, tall, and wrinkle- and blemish-free models are routinely splashed onto billboards, advertisements, and magazine covers. The ubiquity of these unrealistic and highly idealize...
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.1110747108
更新日期:2011-12-13 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::Production of mature erythrocytes requires multiple growth factors, but we do not know how their actions are coordinated. Here we show that erythroid progenitors from erythropoietin receptor (Epo-R)-/- fetal livers, infected in vitro with a retrovirus expressing the wild-type Epo-R, require addition of both Epo and st...
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.94.5.1806
更新日期:1997-03-04 00:00:00
abstract::The DNA in chromatin of isolated thymus nuclei, and in two different preparations of deoxyribonucleoprotein extracted from chromatin, has been digested with DNase. By variation of the time of reaction and the concentration of enzyme, and by comparison of the action of the enzyme on (protein-free) DNA with its action o...
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.68.12.2945
更新日期:1971-12-01 00:00:00
abstract::The ionophores A23187 and bromolasalocid (Br-X537A) acted synergistically in translocating Ca(2+) from an aqueous into an organic immiscible phase or in mediating Ca(2+) transport across the organic phase, the effects obtained in the simultaneous presence of both ionophores being greater than those expected from a sum...
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.78.1.279
更新日期:1981-01-01 00:00:00
abstract::The D1 reaction center protein of photosystem II (PSII) is subject to light-induced damage. Degradation of damaged D1 and its replacement by nascent D1 are at the heart of a PSII repair cycle, without which photosynthesis is inhibited. In mature plant chloroplasts, light stimulates the recruitment of ribosomes specifi...
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.2007833117
更新日期:2020-09-01 00:00:00
abstract::We describe a model for early onset preeclampsia (EOPE) that uses induced pluripotent stem cells (iPSCs) generated from umbilical cords of EOPE and control (CTL) pregnancies. These iPSCs were then converted to placental trophoblast (TB) representative of early pregnancy. Marker gene analysis indicated that both sets o...
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.1816150116
更新日期:2019-03-05 00:00:00
abstract::Accumulating evidence suggests that α-synuclein (α-syn) occurs physiologically as a helically folded tetramer that resists aggregation. However, the mechanisms underlying the regulation of formation of α-syn tetramers are still mostly unknown. Cellular membrane lipids are thought to play an important role in the regul...
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.1700465115
更新日期:2018-01-23 00:00:00
abstract::An in vitro system for replication of lambda dv plasmid DNA has been constructed. This system consists of an ammonium sulfate fraction from Escherichia coli extract, exogenously added purified lambda O and P proteins, and lambda dv DNA in closed circular form. More than 85% of the added template DNA replicated semicon...
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.79.24.7639
更新日期:1982-12-01 00:00:00
abstract::Electron micrographs are shown of the first component of human complement (C1) which has been crosslinked with a water-soluble carbodiimide to prevent dissociation into its C1q and C1r2C1s2 subunits. Two projections of the crosslinked molecule are seen in the electron micrographs, which are called "top" and "profile."...
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.79.2.586
更新日期:1982-01-01 00:00:00