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Cellular Architecture (cellular + architecture)
Selected AbstractsPPP1R9B (Neurabin 2): Involvement and dynamics in the NK immunological synapseEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2009Xiaobo Meng Abstract The NK immunological synapse (NKIS) is a dynamic structure dependent on the assembly of membrane, cytoskeletal and signaling components. These serve to focus and generate stimuli for adhesion and orientation of the cytoskeleton for targeted cytolytic granule release. Previous studies have demonstrated the importance of the cytoskeleton in these processes. We previously identified PPP1R9B (neurabin 2, spinophilin) as a cytoskeletal component of the NK-like cell line YTS. We demonstrate that (i) PPP1R9B gradually accumulates at the NKIS in a maturation stage-dependent manner; (ii) it mimics the early kinetics of actin recruitment to the NKIS but it precedes actin departure from the site; (iii) it is recruited by CD18 stimulation but not by CD28 ligation; (iv) it is required for the maintenance of the cortical F-actin organization in the YTS cells and knocking down PPP1R9B reduces the frequency of YTS,target cell conjugation, possibly due to the collapsed F-actin cytoskeleton in these cells. These results indicate that PPP1R9B is required for synapse formation in the NK cells and suggest that it may be involved in the maintenance of cellular architecture by regulation of actin assembly, possibly acting to stabilize the NKIS until granule release is eminent. [source] Biochemical insights into the mechanisms central to the response of mammalian cells to cold stress and subsequent rewarmingFEBS JOURNAL, Issue 1 2009Anne Roobol Mammalian cells cultured in vitro are able to recover from cold stress. However, the mechanisms activated during cold stress and recovery are still being determined. We here report the effects of hypothermia on cellular architecture, cell cycle progression, mRNA stability, protein synthesis and degradation in three mammalian cell lines. The cellular structures examined were, in general, well maintained during mild hypothermia (27,32 °C) but became increasingly disrupted at low temperatures (4,10 °C). The degradation rates of all mRNAs and proteins examined were much reduced at 27 °C, and overall protein synthesis rates were gradually reduced with temperature down to 20 °C. Proteins involved in a range of cellular activities were either upregulated or downregulated at 32 and 27 °C during cold stress and recovery. Many of these proteins were molecular chaperones, but they did not include the inducible heat shock protein Hsp72. Further detailed investigation of specific proteins revealed that the responses to cold stress and recovery are at least partially controlled by modulation of p53, Grp75 and eIF3i levels. Furthermore, under conditions of severe cold stress (4 °C), lipid-containing structures were observed that appeared to be in the process of being secreted from the cell that were not observed at less severe cold stress temperatures. Our findings shed light on the mechanisms involved and activated in mammalian cells upon cold stress and recovery. [source] A new high-content model system for studies of gastrointestinal transit: the zebrafishNEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2009A. Rich Abstract, The zebrafish gastrointestinal (GI) tract displays an anatomy and cellular architecture that is similar to the human GI tract, with concentric layers of inner epithelia, connective tissue, circular muscle and outer longitudinal muscle layers. Propulsion of luminal content results from the integrated activity of smooth muscle cells, enteric neurons and the interstitial cells of Cajal (ICC). Zebrafish larvae are transparent and propagating contractions in the entire GI tract are easily visualized. A new moderate-throughput zebrafish-based GI transit assay is described in this issue of Neurogastroenterology and Motility. This assay utilizes intact zebrafish larvae which contain essential regulatory elements (ICC and enteric neurons). Forward genetic analysis, which identifies genes underlying specific phenotypes, is possible using the zebrafish system. The zebrafish model system compliments existing models for studies of GI motility and will contribute to the understanding of the regulation of GI motility, and to identification of novel drug targets. [source] Cellular characterization of the gouty tophus: A quantitative analysisARTHRITIS & RHEUMATISM, Issue 5 2010Nicola Dalbeth Objective To characterize the cellular architecture of the tophus and to determine the presence of cytokines implicated in the initiation and resolution of gouty inflammation. Methods Sixteen fixed, paraffin-embedded, uninfected tophus samples were surgically obtained from 12 patients with microscopically proven gout and were analyzed by quantitative immunohistochemistry. The number of cells present in the corona and fibrovascular zones of the tophus was analyzed by Genmod mixed models analysis. Results Numerous CD68+ mononucleated and multinucleated cells were present within the corona zone. Mast cells were identified in all tophus samples and at similar densities throughout the corona and fibrovascular zones. In contrast, neutrophils were rarely observed. Plasma cells were present in very high numbers within the corona zone. The overall number of CD20+ B cells was much lower. However, in 6 of 12 patients (50%), at least 1 B cell aggregate was present in the fibrovascular zone. Large numbers of cells expressing interleukin-1, (IL-1,) were observed in the corona zone. Transforming growth factor ,1 (TGF,1),expressing mononucleated cells were also identified. The number of CD68+ cells correlated with the number of cells expressing IL-1, (r = 0.691, P = 0.009) and the number expressing TGF,1 (r = 0.518, P = 0.04). Conclusion The tophus represents a complex and organized chronic inflammatory tissue response to monosodium urate monohydrate crystals involving both innate and adaptive immune cells. The coexpression of IL-1, and TGF,1 suggests that both proinflammatory and antiinflammatory factors present within the tophus contribute to a cycle of chronic inflammation, attempted resolution, and tissue remodeling. [source] 1,,25-Dihydroxyvitamin D3 inhibits rat liver ultrastructural changes and the development of ,-glutamyltranspeptidase-positive foci in diethylnitrosamine-initiated and streptozotocin-induced diabetes-promoted hepatocarcinogenesisCELL BIOCHEMISTRY AND FUNCTION, Issue 3 2002Barun Kanti Saha Abstract In the present study, the chemopreventive effect of the active metabolite of vitamin D, 1,,25-dihydroxyvitamin D3 (VD3), against chemically-induced and diabetes-promoted rat liver carcinogenesis was investigated. Hepatocarcinogenesis was initiated with a single intraperitoneal (i.p.) injection of diethylnitrosamine (DEN) (125 mg kg,1 body weight) at week 4 followed by promotion with streptozotocin (STZ) (65 mg kg,1 body weight with a single i.p. injection) at week 7. With this basic experimental regimen, the effect of VD3 (0.3 ,g (0.1 ml),1 propylene glycol per os twice a week) was investigated with effect from 4 weeks prior to the exposure of DEN. The results showed that VD3 supplementation throughout the experimental period reduced the incidence, total number and multiplicity and altered the size of visible persistent nodules (PNs) in DEN- or DEN,+,STZ-treated rats as compared with their respective controls. In these two groups, it also caused a significant decrease in the number (p,<,0.002 and 0.001 respectively) and focal area (p,<,0.05) of ,-glutamyltranspeptidase (GGT)-positive hepatic foci. Moreover, continuous supplementation of VD3 exhibits a protective effect in maintaining the normal cellular architecture of the hepatocytes in DEN- or DEN,+,STZ-treated rats. Our results thus strongly suggest that VD3 is very effective in the inhibition of DEN-initiated and STZ-induced diabetes-promoted rat liver carcinogenesis. Copyright © 2002 John Wiley & Sons, Ltd. [source] Comparison of satellite and cellular architectures for downlink broadcast data transmissionINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2007Adarsh Sridhar Abstract Traditional voice and video-oriented networks such as the cellular and satellite networks are being increasingly used to carry data traffic. We endeavour to compare the downlink broadcast performance of the two architectures against each other on the basis of energy consumption, end-to-end delay and maximum stable throughput. The architectures are modelled as systems of Geo/G/1 queues. Queuing theory arguments and then sample-path based comparisons are used to show that the satellite architecture while being more energy-efficient has a higher delay and a lower maximum throughput. The variation of energy and delay with the total number of receiver nodes is also studied. Copyright © 2006 John Wiley & Sons, Ltd. [source] IP-driven access-independent resource management in converged access networksBELL LABS TECHNICAL JOURNAL, Issue 2 2007Markus Bauer A key requirement on future networks is to provide the user with seamless broadband access for triple-play services via any available access technology with high end-to-end quality of service. In this paper we propose a novel resource management concept on the network layer that utilizes service- and user-specific cross-layer metrics to control the resources in an all-Internet Protocol (IP) access network optimally via IP mechanisms such as routing and traffic engineering. We interpret any link, wireless or wireline, as an IP-hop in an all-IP network where major lower layer information is included in such metrics. This approach turns out to be access technology,independent, leading to a unified resource management concept in a "converged" wireline/wireless environment. With this proposal, we leverage flat IP-based cellular architectures like the Alcatel-Lucent Base Station Router (BSR) technologies and show how wireless and wireline access nodes can be integrated into future converged all-IP networks. The paper is based on results from ScaleNet, a European research initiative that is dedicated to advancing a vision of a scalable and flexible next-generation access network that provides an IP-optimized integration of heterogeneous access systems for future broadband multimedia services. © 2007 Alcatel-Lucent. [source] | ||||||||||