排序方式: 共有109条查询结果,搜索用时 154 毫秒
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Jumaa H Bossaller L Portugal K Storch B Lotz M Flemming A Schrappe M Postila V Riikonen P Pelkonen J Niemeyer CM Reth M 《Nature》2003,423(6938):452-456
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Protective role of phospholipid oxidation products in endotoxin-induced tissue damage 总被引:21,自引:0,他引:21
Lipopolysaccharide (LPS), an outer-membrane component of Gram-negative bacteria, interacts with LPS-binding protein and CD14, which present LPS to toll-like receptor 4 (refs 1, 2), which activates inflammatory gene expression through nuclear factor kappa B (NF kappa B) and mitogen-activated protein-kinase signalling. Antibacterial defence involves activation of neutrophils that generate reactive oxygen species capable of killing bacteria; therefore host lipid peroxidation occurs, initiated by enzymes such as NADPH oxidase and myeloperoxidase. Oxidized phospholipids are pro-inflammatory agonists promoting chronic inflammation in atherosclerosis; however, recent data suggest that they can inhibit expression of inflammatory adhesion molecules. Here we show that oxidized phospholipids inhibit LPS-induced but not tumour-necrosis factor-alpha-induced or interleukin-1 beta-induced NF kappa B-mediated upregulation of inflammatory genes, by blocking the interaction of LPS with LPS-binding protein and CD14. Moreover, in LPS-injected mice, oxidized phospholipids inhibited inflammation and protected mice from lethal endotoxin shock. Thus, in severe Gram-negative bacterial infection, endogenously formed oxidized phospholipids may function as a negative feedback to blunt innate immune responses. Furthermore, identified chemical structures capable of inhibiting the effects of endotoxins such as LPS could be used for the development of new drugs for treatment of sepsis. 相似文献
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Greenman C Stephens P Smith R Dalgliesh GL Hunter C Bignell G Davies H Teague J Butler A Stevens C Edkins S O'Meara S Vastrik I Schmidt EE Avis T Barthorpe S Bhamra G Buck G Choudhury B Clements J Cole J Dicks E Forbes S Gray K Halliday K Harrison R Hills K Hinton J Jenkinson A Jones D Menzies A Mironenko T Perry J Raine K Richardson D Shepherd R Small A Tofts C Varian J Webb T West S Widaa S Yates A Cahill DP Louis DN Goldstraw P Nicholson AG Brasseur F Looijenga L Weber BL Chiew YE DeFazio A 《Nature》2007,446(7132):153-158
Cancers arise owing to mutations in a subset of genes that confer growth advantage. The availability of the human genome sequence led us to propose that systematic resequencing of cancer genomes for mutations would lead to the discovery of many additional cancer genes. Here we report more than 1,000 somatic mutations found in 274 megabases (Mb) of DNA corresponding to the coding exons of 518 protein kinase genes in 210 diverse human cancers. There was substantial variation in the number and pattern of mutations in individual cancers reflecting different exposures, DNA repair defects and cellular origins. Most somatic mutations are likely to be 'passengers' that do not contribute to oncogenesis. However, there was evidence for 'driver' mutations contributing to the development of the cancers studied in approximately 120 genes. Systematic sequencing of cancer genomes therefore reveals the evolutionary diversity of cancers and implicates a larger repertoire of cancer genes than previously anticipated. 相似文献
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Sonic hedgehog (Shh) has been implicated in the ongoing neurogenesis in postnatal rodent brains. Here we adopted an in vivo genetic fate-mapping strategy, using Gli1 (GLI-Kruppel family member) as a sensitive readout of Shh activity, to systematically mark and follow the fate of Shh-responding cells in the adult mouse forebrain. We show that initially, only a small population of cells (including both quiescent neural stem cells and transit-amplifying cells) responds to Shh in regions undergoing neurogenesis. This population subsequently expands markedly to continuously provide new neurons in the forebrain. Our study of the behaviour of quiescent neural stem cells provides in vivo evidence that they can self-renew for over a year and generate multiple cell types. Furthermore, we show that the neural stem cell niches in the subventricular zone and dentate gyrus are established sequentially and not until late embryonic stages. 相似文献
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This paper explores how the boundaries of the UK's Animals (Scientific Procedures) Act (A(SP)A) are constituted, as illustrative of the rising importance of legal procedures around animal research and how these are continuously being challenged and questioned. Drawing on empirical work in animal research communities, we consider how it is decided whether activities are undertaken for an “experimental or other scientific purpose”. We do this by focusing on “edge cases”, where debates occur about whether to include an activity within A(SP)A's remit. We demonstrate that the boundaries of animal research regulation in the UK are products of past and present decisions, dependencies, and social relationships. Boundaries are therefore not clear-cut and fixed, but rather flexible and changing borderlands. We particularly highlight the roles of: historical precedent; the management of risk, workload, and cost; institutional and professional identities; and research design in constituting A(SP)A's edges. In doing so, we demonstrate the importance of paying attention to how, in practice, animal law requires a careful balance between adhering to legal paragraphs and allowing for discretion. This in turn has real-world implications for what and how science is done, who does it, and how animals are used in its service. 相似文献
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Evidence for complete denitrification in a benthic foraminifer 总被引:2,自引:0,他引:2
Risgaard-Petersen N Langezaal AM Ingvardsen S Schmid MC Jetten MS Op den Camp HJ Derksen JW Piña-Ochoa E Eriksson SP Nielsen LP Revsbech NP Cedhagen T van der Zwaan GJ 《Nature》2006,443(7107):93-96
Benthic foraminifera are unicellular eukaryotes found abundantly in many types of marine sediments. Many species survive and possibly reproduce in anoxic habitats, but sustainable anaerobic metabolism has not been previously described. Here we demonstrate that the foraminifer Globobulimina pseudospinescens accumulates intracellular nitrate stores and that these can be respired to dinitrogen gas. The amounts of nitrate detected are estimated to be sufficient to support respiration for over a month. In a Swedish fjord sediment where G. pseudospinescens is the dominant foraminifer, the intracellular nitrate pool in this species accounted for 20% of the large, cell-bound, nitrate pool present in an oxygen-free zone. Similarly high nitrate concentrations were also detected in foraminifera Nonionella cf. stella and a Stainforthia species, the two dominant benthic taxa occurring within the oxygen minimum zone of the continental shelf off Chile. Given the high abundance of foraminifera in anoxic marine environments, these new findings suggest that foraminifera may play an important role in global nitrogen cycling and indicate that our understanding of the complexity of the marine nitrogen cycle is far from complete. 相似文献
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Estevão Alves-Silva Alexandra Bächtold Gudryan Jackson Barônio Helena Maura Torezan-Silingardi Kleber Del-Claro 《Journal of Natural History》2015,49(13-14):841-851
Extrafloral nectary drinking ants are known as effective plant guards, but some herbivores may circumvent ant attacks by foraging on different plant parts or presenting adaptations to avoid ant predation. Here we experimentally investigated the effect of Camponotus blandus on the florivory of the extrafloral nectaried shrub Banisteriopsis malifolia; and a possible spatial segregation between ants and herbivores (leaves and flowers). Flower buds are attacked by Anthonomus weevils. Results revealed no significant influence of C. blandus on the reduction of florivory. Adult Anthonomus are hard-bodied and were immune to ant bites; larvae are endophytic, so protected from ants. Ants and adult beetles were concentrated in different plant parts (leaves and flowers, respectively) so restraining the probability of encounters. Our results indicate that the system C. blandus–Anthonomus–B. malifolia is not stable, as ants receive extrafloral nectar, but are unable to protect the plant against weevils. 相似文献
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