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991.
Bruey JM Bruey-Sedano N Luciano F Zhai D Balpai R Xu C Kress CL Bailly-Maitre B Li X Osterman A Matsuzawa S Terskikh AV Faustin B Reed JC 《Cell》2007,129(1):45-56
Caspases are intracellular proteases that cleave substrates involved in apoptosis or inflammation. In C. elegans, a paradigm for caspase regulation exists in which caspase CED-3 is activated by nucleotide-binding protein CED-4, which is suppressed by Bcl-2-family protein CED-9. We have identified a mammalian analog of this caspase-regulatory system in the NLR-family protein NALP1, a nucleotide-dependent activator of cytokine-processing protease caspase-1, which responds to bacterial ligand muramyl-dipeptide (MDP). Antiapoptotic proteins Bcl-2 and Bcl-X(L) bind and suppress NALP1, reducing caspase-1 activation and interleukin-1beta (IL-1beta) production. When exposed to MDP, Bcl-2-deficient macrophages exhibit more caspase-1 processing and IL-1beta production, whereas Bcl-2-overexpressing macrophages demonstrate less caspase-1 processing and IL-1beta production. The findings reveal an interaction of host defense and apoptosis machinery. 相似文献
992.
Apurva Bhargava Milan Osusky Benjamin S. Forward Robert E. Hancock William W. Kay Santosh Misra 《Plant Cell, Tissue and Organ Culture》2007,88(3):301-312
Antimicrobial cationic peptides provide a promising means of engineering plant resistance to a range of plant pathogens, including
viruses. PV5 is a synthetic structural variant of polyphemusin, a cationic peptide derived from the horseshoe crab-Limulus polyphemus. PV5 has been shown to be benign toward eukaryotic membranes but with enhanced antimicrobial activity against animal pathogens.
In this work, the cytotoxicity of PV5 toward tobacco protoplasts and leaf discs was assessed using TTC (2,3,5-triphenyltetrazolium
chloride) and Evans blue colorimetric assays. PV5 showed no measurable cytotoxic effects even at levels as high as 60 μg.
As a possible approach to enhancing plant resistance, a gene encoding PV5 was fused to the signal sequence encoding the C-terminus
portion of the BiP protein from Pseudotsuga menziesii, under the control of 2 × 35S CaMV promoter. When introduced into Nicotiana tabacum var Xanthi gene integration and expression was confirmed by both Southern and northern analyses. When transgenic plants were
subsequently challenged with bacterial and fungal phytopathogens enhanced resistance was observed. Moreover, transgenic plants
also displayed antiviral properties against Tobacco Mosaic Virus making PV5 an excellent candidate for conferring unusually
broad spectrum resistance to plants and the first anti-plant virus antimicrobial peptide. 相似文献
993.
When observing art the viewer's understanding results from the interplay between the marks made on the surface by the artist and the viewer's perception and knowledge of it. Here we use a novel set of stimuli to dissociate the influences of the marks on the surface and the viewer's perceptual experience upon the manner in which the viewer inspects art. Our stimuli provide the opportunity to study situations in which (1) the same visual stimulus can give rise to two different perceptual experiences in the viewer, and (2) the visual stimuli differ but give rise to the same perceptual experience in the viewer. We find that oculomotor behaviour changes when the perceptual experience changes. Oculomotor behaviour also differs when the viewer's perceptual experience is the same but the visual stimulus is different. The methodology used and insights gained from this study offer a first step toward an experimental exploration of the relative influences of the artist's creation and viewer's perception when viewing art and also toward a better understanding of the principles of composition in portraiture. 相似文献
994.
Parthenolide sensitizes cells to X-ray-induced cell killing through inhibition of NF-kappaB and split-dose repair 总被引:2,自引:0,他引:2
Mendonca MS Chin-Sinex H Gomez-Millan J Datzman N Hardacre M Comerford K Nakshatri H Nye M Benjamin L Mehta S Patino F Sweeney C 《Radiation research》2007,168(6):689-697
Human cancers have multiple alterations in cell signaling pathways that promote resistance to cytotoxic therapy such as X rays. Parthenolide is a sesquiterpene lactone that has been shown to inhibit several pro-survival cell signaling pathways, induce apoptosis, and enhance chemotherapy-induced cell killing. We investigated whether parthenolide would enhance X-ray-induced cell killing in radiation resistant, NF-kappaB-activated CGL1 cells. Treatment with 5 microM parthenolide for 48 to 72 h inhibited constitutive NF-kappaB binding and cell growth, reduced plating efficiency, and induced apoptosis through stabilization of p53 (TP53), induction of the pro-apoptosis protein BAX, and phosphorylation of BID. Parthenolide also enhanced radiation-induced cell killing, increasing the X-ray sensitivity of CGL1 cells by a dose modification factor of 1.6. Flow cytometry revealed that parthenolide reduced the percentage of X-ray-resistant S-phase cells due to induction of p21 waf1/cip1 (CDKN1A) and the onset of G1/S and G2/M blocks, but depletion of radioresistant S-phase cells does not explain the observed X-ray sensitization. Further studies demonstrated that the enhancement of X-ray-induced cell killing by parthenolide is due to inhibition of split-dose repair. 相似文献
995.
996.
Stich B Melchinger AE Piepho HP Hamrit S Schipprack W Maurer HP Reif JC 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(4):529-536
Knowledge about the forces generating and conserving linkage disequilibrium (LD) is important for drawing conclusions about
the prospects and limitations of association mapping. The objectives of our research were to examine the importance of (1)
selection, (2) mutation, and (3) genetic drift for generating LD in a typical maize breeding program. We conducted computer
simulations based on genotypic data of Central European maize open-pollinated varieties which have played an important role
as founders of the European flint heterotic group. The breeding scheme and the dimensioning underlying our simulations reflect
essentially the maize breeding program of the University of Hohenheim. Results suggested that in a plant breeding program
of the examined dimension and breeding scheme, genetic drift and selection are major forces generating LD. The currently used
population-based association mapping tests do not explicitly correct for LD caused by these two forces. Therefore, increased
type I error rates are expected if these tests are applied to plant breeding populations. As a consequence, we recommend to
use family-based association tests for association mapping approaches in plant breeding populations. 相似文献
997.
Stone KL Bjornson RD Blasko GG Bruce C Cofrancesco R Carriero NJ Colangelo CM Crawford JK Crawford JM daSilva NC Deluca JD Elliott JI Elliott MM Flory PJ Folta-Stogniew EJ Gulcicek E Kong Y Lam TT Lee JY Lin A LoPresti MB Mane SM McMurray WJ Tikhonova IR Westman S Williams NA Wu TL Hongyu Z Williams KR 《The Yale journal of biology and medicine》2007,80(4):195-211
998.
Configural information has long been considered important for face recognition. However, traditional portraiture instruction encourages the artist to use a 'generic' configuration for faces rather than attempting to replicate precise feature positions. We examine this intriguing paradox with two tasks designed to test the extent to which configural information is incorporated into face representations. In Experiment 1, we use a simplified face production task to examine how accurately feature configuration can be incorporated in the generated likenesses. In Experiment 2, we ask if the 'portraits' created in Experiment 1 are discriminable from veridical images. The production and recognition results from these experiments show a consistent pattern. Subjects are quite poor at arranging facial features (eyes, nose and mouth) in their correct locations, and at distinguishing erroneous configurations from correct ones. This seeming insensitivity to configural relations is consistent with artists' practice of creating portraits based on a generic geometric template. Interestingly, the frame of reference artists implicitly use for this generic template - the external face contour - emerges as a significant modulator of performance in our experimental results. Production errors are reduced and recognition performance is enhanced in the presence of outer contours. We discuss the implications of these results for face recognition models, as well as some possible perceptual reasons why portraits are so difficult to create. 相似文献
999.
Breckenridge SM Raju B Arbelaez AM Patterson BW Cooperberg BA Cryer PE 《American journal of physiology. Endocrinology and metabolism》2007,293(5):E1303-E1310
Conclusions drawn from the pancreatic (or islet) clamp technique (suppression of endogenous insulin, glucagon, and growth hormone secretion with somatostatin and replacement of basal hormone levels by intravenous infusion) are critically dependent on the biological appropriateness of the selected doses of the replaced hormones. To assess the appropriateness of representative doses we infused saline alone, insulin (initially 0.20 mU.kg(-1).min(-1)) alone, glucagon (1.0 ng.kg(-1).min(-1)) alone, and growth hormone (3.0 ng.kg(-1).min(-1)) alone intravenously for 4 h in 13 healthy individuals. That dose of insulin raised plasma insulin concentrations approximately threefold, suppressed glucose production, and drove plasma glucose concentrations down to subphysiological levels (65 +/- 3 mg/dl, P < 0.0001 vs. saline), resulting in nearly complete suppression of insulin secretion (P < 0.0001) and stimulation of glucagon (P = 0.0059) and epinephrine (P = 0.0009) secretion. An insulin dose of 0.15 mU.kg(-1).min(-1) caused similar effects, but a dose of 0.10 mU.kg(-1).min(-1) did not. The glucagon and growth hormone infusions did not alter plasma glucose levels or those of glucoregulatory factors. Thus, insulin "replacement" doses of 0.20 and even 0.15 mU.kg(-1).min(-1) are excessive, and conclusions drawn from the pancreatic clamp technique using such doses may need to be reassessed. 相似文献
1000.
Suárez Y Shepherd BR Rao DA Pober JS 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(11):7488-7496
There is considerable interest in exploiting circulating endothelial progenitor cells (EPCs) for therapeutic organ repair. Such cells may be differentiated into endothelial cells (ECs) in vitro and then expanded for use in tissue engineering. Vessel-derived ECs are variably immunogenic, depending upon tissue source, and it is unknown whether ECs derived from cord blood EPCs are able to initiate an allogeneic response. In this study, we compare the phenotype and alloantigenicity of human cord blood progenitor cell-derived ECs with HUVECs isolated from the same donors. Human cord blood progenitor cell-derived ECs are very similar to HUVECs in the expression of proteins relevant for alloimmunity, including MHC molecules, costimulators, adhesion molecules, cytokines, chemokines, and IDO, and in their ability to initiate allogeneic CD4(+) and CD8(+) memory T cell responses in vitro and in vivo. These findings have significant implications for the use of cord blood EPCs in regenerative medicine or tissue engineering. 相似文献