Abstract:
:The mechanism of contrast enhancement of tumors using magnetic resonance imaging was investigated in MCF7 human breast cancer implanted in nude mice. Dynamic contrast-enhanced images recorded at high spatial resolution were analyzed by an image analysis method based on a physiological model, which included the blood circulation, the tumor, the remaining tissues, and clearance via the kidneys. This analysis enabled us to map in rapidly enhancing regions within the tumor, the capillary permeability factor (capillary permeability times surface area per voxel volume) and the fraction of leakage space. Correlation of these maps with T2-weighted spin echo images, with histopathology, and with immunohistochemical staining of endothelial cells demonstrated the presence of dense permeable microcapillaries in the tumor periphery and in intratumoral regions that surrounded necrotic loci. The high leakage from the intratumoral permeable capillaries indicated an induction of a specific angiogenic process associated with stress conditions that cause necrosis. This induction was augmented in tumors responding to tamoxifen treatment. Determination of the distribution and extent of this stress-induced angiogenic activity by contrast-enhanced MRI might be of diagnostic and of prognostic value.
journal_name
Proc Natl Acad Sci U S Aauthors
Furman-Haran E,Margalit R,Grobgeld D,Degani Hdoi
10.1073/pnas.93.13.6247subject
Has Abstractpub_date
1996-06-25 00:00:00pages
6247-51issue
13eissn
0027-8424issn
1091-6490journal_volume
93pub_type
杂志文章abstract::Activation-induced cytidine deaminase (AID) introduces single-strand breaks (SSBs) to initiate class switch recombination (CSR), gene conversion (GC), and somatic hypermutation (SHM). CSR is mediated by double-strand breaks (DSBs) at donor and acceptor switch (S) regions, followed by pairing of DSB ends in two S regio...
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.1324057111
更新日期:2014-02-11 00:00:00
abstract::Urbanization represents an extreme transformation of more natural systems. Populations of most species decline or disappear with urbanization, and yet some species persist and even thrive in cities. What determines which species persist or thrive in urban habitats? Direct competitive interactions among species can inf...
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.1809317115
更新日期:2018-12-04 00:00:00
abstract::Because virtually all organisms compete with others in their social environment, mechanisms that reduce conflict between interacting individuals are crucial for the evolution of stable families, groups, and societies. Here, we tested whether costs of social conflict over territorial space between Seychelles warblers (...
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.1704350114
更新日期:2017-10-24 00:00:00
abstract::The translational apparatus in cell-free extracts prepared from L cells infected with reovirus undergoes a time-dependent transition from cap dependence to cap independence. Extracts from uninfected L cells translate capped reovirus mRNA at high efficiency and synthesize the expected three size classes of reovirus pol...
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.77.1.152
更新日期:1980-01-01 00:00:00
abstract::Gentamicin C complex from Micromonospora echinospora remains a globally important antibiotic, and there is revived interest in the semisynthesis of analogs that might show improved therapeutic properties. The complex consists of five components differing in their methylation pattern at one or more sites in the molecul...
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.1711603115
更新日期:2018-02-06 00:00:00
abstract::We report that oxytocin (Oxt) receptors (Oxtrs), on stimulation by the ligand Oxt, translocate into the nucleus of osteoblasts, implicating this process in the action of Oxt on osteoblast maturation. Sequential immunocytochemistry of intact cells or isolated nucleoplasts stripped of the outer nuclear membrane showed 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.1419349111
更新日期:2014-11-18 00:00:00
abstract::Adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Recent studies have identified general patterns in adaptive radiation and inferred that resource competition is a primary factor driving phenotypic divergence. The role and importance of other processes, su...
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.0601575103
更新日期:2006-06-13 00:00:00
abstract::Overexpression of the p53 protein, resulting from gene mutations that increase protein stability, has been detected in greater than 25% of primary human breast cancers. In addition, approximately 10% of breast cancer patients have circulating antibodies to the p53 protein. In this study, the anti-p53 humoral response ...
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.89.8.3439
更新日期:1992-04-15 00:00:00
abstract::Fragility is an empirical property that describes how abruptly a glass-forming material solidifies upon supercooling. The degree of fragility carries important implications for the functionality and processability of a material, as well as for our fundamental understanding of the glass transition. However, the microst...
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.1912571116
更新日期:2019-12-10 00:00:00
abstract::Recent studies have shown that genes involved in oxidative phosphorylation (OXPHOS) exhibit reduced expression in skeletal muscle of diabetic and prediabetic humans. Moreover, these changes may be mediated by the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alph...
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.0401401101
更新日期:2004-04-27 00:00:00
abstract::Confronted with an object of perception, an individual will spontaneously try to identify unambiguously and consistently all its parts; except in rare instances of "illusory phenomena," he will immediately succeed. This elementary fact is formalized in a law of visual perception. It is used to define sets of stable 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.75.4.2049
更新日期:1978-04-01 00:00:00
abstract::An oligoribonucleotide (a 27-mer) that mimics the sarcin/ricin (S/R) domain of Escherichia coli 23S rRNA binds elongation factor EF-G; the Kd is 6.9 microM, whereas for binding to ribosomes it is 0.7 microM. Binding saturates when EF-G and the S/R RNA are equimolar; at saturation 70% of the input RNA is in complexes 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.94.23.12280
更新日期:1997-11-11 00:00:00
abstract::The p53 tumor suppressor protein and the MDM2 oncoprotein form a feedback-control loop that up-regulates cellular MDM2 production, blocks p53 activity, and promotes p53 decay. tsg101 was discovered as a gene whose deficiency results in neoplastic transformation of NIH 3T3 cells and the ability to generate metastatic t...
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.98.4.1619
更新日期:2001-02-13 00:00:00
abstract::In many cell-signaling pathways, information is transmitted by the diffusion of messenger molecules. Diffusion coefficients characterize the messenger's spatial range and the characteristic times of signal propagation. Inside cells, particles usually diffuse in the presence of immobile binding sites (or traps). It 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.0509576103
更新日期:2006-04-04 00:00:00
abstract::By adapting to sustained stimuli, hair cells in the internal ear retain their sensitivity to minute transient displacements. Because one model for adaptation asserts that this process is mediated by a myosin isozyme, we reasoned that we should be able to arrest adaptation by interfering with myosin's ATPase cycle thou...
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.90.7.2710
更新日期:1993-04-01 00:00:00
abstract::Constitutive cyclooxygenase (COX-1; prostaglandin-endoperoxide synthase, EC 1.14.99.1) is present in cells under physiological conditions, whereas COX-2 is induced by some cytokines, mitogens, and endotoxin presumably in pathological conditions, such as inflammation. Therefore, we have assessed the relative inhibitory...
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.90.24.11693
更新日期:1993-12-15 00:00:00
abstract::Mahler proved the following quantitative result supplementing the Lindemann-Weierstrass theorem: Sigma(i=0) (n)C(i)e(ri) > H(-n-epsilon) for any distinct rational numbers r(0),r(1),..., r(n) and rational integers C(0),C(1),...,C(n) with H = max(0=i=n) C(i). We improve Mahler's estimate by replacing exponentials 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.80.10.3138
更新日期:1983-05-01 00:00:00
abstract::C6 astrocytoma cells contain beta-adrenergic receptors coupled to adenylate cyclase. A 2-hr exposure to l-isoproterenol results in an 80% decrease in cyclic AMP production in response to a subsequent challenge by l-isoproterenol (desensitization). This loss in responsiveness is paralleled by a 20-30% decrease in 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.77.3.1341
更新日期:1980-03-01 00:00:00
abstract::A family of nanoscale-sized supramolecular cage compounds with a polyhedral framework is prepared by self-assembly from tritopic building blocks and rectangular corner units via noncovalent coordination interactions. These highly symmetrical cage compounds are described as face-directed, self-assembled truncated tetra...
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.030264697
更新日期:2000-02-15 00:00:00
abstract::A 43-kDa peripheral membrane protein is known to copurify with acetylcholine receptor (AcChoR)-rich membranes isolated from the electric organ of Torpedo californica. Immunoelectron microscopy and crosslinking studies have demonstrated that this 43-kDa protein is closely associated with the cytoplasmic domain(s) 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.82.23.8270
更新日期:1985-12-01 00:00:00
abstract::The cDNA sequences encoding the adult alpha- and beta-globin polypeptides of a marsupial, the native cat Dasyurus viverrinus, have been cloned and their nucleotide sequences have been determined. Using these cDNA clones we have determined the chromosomal location of the native cat alpha- and beta-globin genes by in si...
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.82.23.8105
更新日期:1985-12-01 00:00:00
abstract::Peptide nucleic acid (PNA) is a DNA mimic that has shown considerable promise as a lead compound for developing gene therapeutic drugs. We report that PNAs targeted to functional and accessible sites in ribosomal RNA can inhibit translation in an Escherichia coli cell-free transcription/translation system, with 50% re...
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.95.5.2073
更新日期:1998-03-03 00:00:00
abstract::The folding energetics of the mono-N-glycosylated adhesion domain of the human immune cell receptor cluster of differentiation 2 (hCD2ad) were studied systematically to understand the influence of the N-glycan on the folding energy landscape. Fully elaborated N-glycan structures accelerate folding by 4-fold and stabil...
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.0810318105
更新日期:2009-03-03 00:00:00
abstract::The Arctic Ocean already experiences areas of low pH and high CO2, and it is expected to be most rapidly affected by future ocean acidification (OA). Copepods comprise the dominant Arctic zooplankton; hence, their responses to OA have important implications for Arctic ecosystems, yet there is little data on their curr...
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.1315162110
更新日期:2013-12-17 00:00:00
abstract::Human infants are predisposed to rapidly acquire their native language. The nature of these predispositions is poorly understood, but is crucial to our understanding of how infants unpack their speech input to recover the fundamental word-like units, assign them referential roles, and acquire the rules that govern the...
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.1017617108
更新日期:2011-04-12 00:00:00
abstract::Sets of Burkitt lymphoma lines and Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) derived from the same individuals were compared for sensitivity to cytotoxic T-lymphocyte (CTL) clones. Major histocompatibility complex class I antigen-restricted CTL clones were generated by stimulating the lymph...
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.83.15.5620
更新日期:1986-08-01 00:00:00
abstract::DNA toroids produced by the condensation of lambda phage DNA with hexammine cobalt (III) have been investigated by cryoelectron microscopy. Image resolution obtained by this technique has allowed unprecedented views of DNA packing within toroidal condensates. Toroids oriented coplanar with the microscope image plane 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.261560398
更新日期:2001-12-18 00:00:00
abstract::Insights into the pathogenesis of migraine with aura may be gained from a study of human Ca(V)2.1 channels containing mutations linked to familial hemiplegic migraine (FHM). Here, we extend the previous single-channel analysis to human Ca(V)2.1 channels containing mutation V1457L. This mutation increased the channel 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.192242399
更新日期:2002-10-01 00:00:00
abstract::Low phosphate (Pi) availability is one of the major constraints for plant productivity in natural and agricultural ecosystems. Plants have evolved a myriad of developmental and biochemical mechanisms to increase internal Pi uptake and utilization efficiency. One important biochemical pathway leading to an increase 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.0600863103
更新日期:2006-04-25 00:00:00
abstract::ALS is a terminal disease of motor neurons that is characterized by accumulation of proteinaceous deposits in affected cells. Pathological deposition of mutated Cu/Zn superoxide dismutase (SOD1) accounts for ∼20% of the familial ALS (fALS) cases. However, understanding the molecular link between mutation and disease h...
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.1320786110
更新日期:2014-01-07 00:00:00