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101.
Transmissible spongiform encephalopathies (TSEs) or prion diseases are infectious neurological disorders of man and animals, characterised by abnormal disease-associated prion protein (PrPd) accumulations in the brain and lymphoreticular system (LRS). Prior to neuroinvasion, TSE agents often accumulate to high levels within the LRS, apparently without affecting immune function. However, our analysis of scrapie-affected sheep shows that PrPd accumulations within the LRS are associated with morphological changes to follicular dendritic cells (FDCs) and tingible body macrophages (TBMs). Here we examined FDCs and TBMs in the mesenteric lymph nodes (MLNs) of scrapie-affected mice by light and electron microscopy. In MLNs from uninfected mice, FDCs could be morphologically categorised into immature, mature and regressing forms. However, in scrapie-affected MLNs this maturation cycle was adversely affected. FDCs characteristically trap and retain immune complexes on their surfaces, which they display to B-lymphocytes. In scrapie-affected MLNs, some FDCs were found where areas of normal and abnormal immune complex retention occurred side by side. The latter co-localised with PrPd plasmalemmal accumulations. Our data suggest this previously unrecognised morphology represents the initial stage of an abnormal FDC maturation cycle. Alterations to the FDCs included PrPd accumulation, abnormal cell membrane ubiquitin and excess immunoglobulin accumulation. Regressing FDCs, in contrast, appeared to lose their membrane-attached PrPd. Together, these data suggest that TSE infection adversely affects the maturation and regression cycle of FDCs, and that PrPd accumulation is causally linked to the abnormal pathology observed. We therefore support the hypothesis that TSEs cause an abnormality in immune function. 相似文献
102.
Outer membrane vesicles (OMVs) shed from the gastroduodenal pathogen Helicobacter pylori have measurable effects on epithelial cell responses. The aim of this study was to determine the effect of iron availability, and its basis, on the extent and nature of lipopolysaccharide (LPS) produced on H. pylori OMVs and their parental bacterial cells. Electrophoretic, immunoblotting and structural analyses revealed that LPSs of bacterial cells grown under iron-limited conditions were notably shorter than those of bacteria and OMVs obtained from iron-replete conditions. Structural analysis and serological probing showed that LPSs of iron-replete cells and OMVs expressed O-chains of Lewis(x) with a terminal Lewis(y) unit, whereas Lewis(y) expression was notably reduced on bacteria and OMVs from iron-limiting conditions. Unlike the O-chain, the core oligosaccharide and lipid A moieties of iron-replete and iron-limited bacteria and their OMVs were similar. Quantitatively, shed OMVs from iron-replete bacteria were found to be LPSenriched, whereas shed OMVs from iron-limited bacteria had a significantly reduced content of LPS. These differences were linked to bacterial ATP levels. Since iron availability affects the extent and nature of LPS expressed by H. pylori, host iron status may contribute to H. pylori pathogenesis. 相似文献
103.
104.
Mattson RJ Catt JD Sloan CP Gao Q Carter RB Gentile A Mahle CD Matos FF McGovern R VanderMaelen CP Yocca FD 《Bioorganic & medicinal chemistry letters》2003,13(2):285-288
A new 5-HT(1A) silent antagonist 14 (5-HT(1A) IC(50)=2.2 nM) antagonizes the effects of agonists on reciprocal forepaw treading behavior, on neuronal firing in the rat dorsal raphé, and on 5-HT(1A) release in the raphé and hippocampus. While 14 alone was inactive in the social interaction paradigm, it completely reversed the social interaction activity of the serotonergic compounds (buspirone, 1, and 2). 相似文献
105.
Assays of malathion content and toxicity to boll weevil, Anthonomus grandis grandis Bohemian, were conducted on boll weevil bait sticks, now marketed as Boll Weevil Attract and Control Tubes (BWACTs; Plato Industries, Houston, TX). In general, the longer BWACTs were in the field, the lower the mortality of weevils that were exposed to them. Bioassays of weevil mortality correlated with hexane washes of BWACT surfaces showed highly variable mortality when surface malathion fell below approximately 20 ng per 1 microl of hexane, but consistently high mortality (> or = 90%) when surface malathion was above 30 ng per 1 microl of hexane. A linear equation was calculated to predict mortality as a function of malathion on a BWACT surface. Although mortality was related to surface amounts of malathion, it was unrelated to the total amount of malathion present in BWACTs. Similarly, surface malathion was unrelated to the total amount present in BWACTs. As with mortality, amount of surface malathion declined with time, but total malathion did not decline with time. Boll weevils placed on fresh BWACTs tended to accumulate more malathion and died in greater numbers as time spent on fresh tubes increased, but not as time spent on tubes aged in the field (for 5 mo total) increased. Weevils that landed on tubes after a short flight died in approximately the same numbers as those that were placed on tubes using proper methodology. The amount of malathion expected to cause 90% mortality of boll weevils subjected to proper methodology was 47% higher than for a less stringent methodology (34.3 versus 23.4 ng), which demonstrates the importance of strictly adhering to proper methodology; nevertheless, chemical assay of malathion on the BWACT surface proved to be a more consistent measure of BWACT toxicity than bioassay, and it should replace the bioassay. 相似文献
106.
Broad specificity of virus-specific CD4+ T-helper-cell responses in resolved hepatitis C virus infection 总被引:1,自引:0,他引:1
Day CL Lauer GM Robbins GK McGovern B Wurcel AG Gandhi RT Chung RT Walker BD 《Journal of virology》2002,76(24):12584-12595
Vigorous virus-specific CD4+ T-helper-cell responses are associated with successful control of hepatitis C virus (HCV) and other human viral infections, but the breadth and specificity of responses associated with viral containment have not been defined. To address this we evaluated the HCV-specific CD4+ T-helper-cell response in HCV antibody-positive persons who lack detectable plasma viremia, and compared this response to that in persons with chronic HCV infection. Peripheral blood mononuclear cells were stimulated with HCV proteins, followed by measurement of HCV-specific CD4+ T-cell responses to a comprehensive set of overlapping HCV peptides by intracellular gamma interferon production. In three persons with resolved HCV infection studied in detail, 13 to 14 epitopes were targeted, but none was recognized by all three. The 37 defined epitopes were predominantly distributed among the HCV proteins core, NS3, NS4, and NS5. In an expanded analysis of responses to these proteins in persons with resolved infection, an average of 10 epitopes was targeted, whereas in persons with chronic viremia never was more than one epitope targeted (P < 0.001). This comprehensive analysis of the breadth and specificity of HCV-specific T-helper-cell responses indicates that up to 14 viral epitopes can be simultaneously targeted by circulating virus-specific CD4+ T helper cells in a controlled human viral infection. Moreover, these data provide important parameters for evaluation of candidate HCV vaccines, and provide rationale for immunotherapy in chronic HCV infection. 相似文献
107.
Temporary blockade of the tumor necrosis factor receptor signaling pathway impedes the spread of scrapie to the brain
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Although the transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases, their agents usually replicate and accumulate in lymphoid tissues long before infection spreads to the central nervous system (CNS). Studies of a mouse scrapie model have shown that mature follicular dendritic cells (FDCs), which express the host prion protein (PrP(c)), are critical for replication of infection in lymphoid tissues. In the absence of mature FDCs, the spread of infection to the CNS is significantly impaired. Tumor necrosis factor alpha (TNF-alpha) secretion by lymphocytes is important for maintaining FDC networks, and signaling is mediated through TNF receptor 1 (TNFR-1) expressed on FDCs and/or their precursors. A treatment that blocks TNFR signaling leads to the temporary dedifferentiation of mature FDCs, raising the hypothesis that a similar treatment would significantly delay the peripheral pathogenesis of scrapie. Here, specific neutralization of the TNFR signaling pathway was achieved through treatment with a fusion protein consisting of two soluble human TNFR (huTNFR) (p80) domains linked to the Fc portion of human immunoglobulin G1 (huTNFR:Fc). A single treatment of mice with huTNFR:Fc before or shortly after intraperitoneal injection with the ME7 scrapie strain significantly delayed the onset of disease in the CNS and reduced the early accumulation of disease-specific PrP in the spleen. These effects coincided with a temporary dedifferentiation of mature FDCs within 5 days of huTNFR:Fc treatment. We conclude that treatments that specifically inhibit the TNFR signaling pathway may present an opportunity for early intervention in peripherally transmitted TSEs. 相似文献
108.
Leptin receptor signaling in POMC neurons is required for normal body weight homeostasis 总被引:21,自引:0,他引:21
Balthasar N Coppari R McMinn J Liu SM Lee CE Tang V Kenny CD McGovern RA Chua SC Elmquist JK Lowell BB 《Neuron》2004,42(6):983-991
Neuroanatomical and electrophysiological studies have shown that hypothalamic POMC neurons are targets of the adipostatic hormone leptin. However, the physiological relevance of leptin signaling in these neurons has not yet been directly tested. Here, using the Cre/loxP system, we critically test the functional importance of leptin action on POMC neurons by deleting leptin receptors specifically from these cells in mice. Mice lacking leptin signaling in POMC neurons are mildly obese, hyperleptinemic, and have altered expression of hypothalamic neuropeptides. In summary, leptin receptors on POMC neurons are required but not solely responsible for leptin's regulation of body weight homeostasis. 相似文献
109.
110.
The axr6 mutants of Arabidopsis thaliana define a gene involved in auxin response and early development 总被引:9,自引:0,他引:9
Hobbie L McGovern M Hurwitz LR Pierro A Liu NY Bandyopadhyay A Estelle M 《Development (Cambridge, England)》2000,127(1):23-32
The indolic compound auxin regulates virtually every aspect of plant growth and development, but its role in embryogenesis and its molecular mechanism of action are not understood. We describe two mutants of Arabidopsis that define a novel gene called AUXIN-RESISTANT6 (AXR6) which maps to chromosome 4. Embryonic development of the homozygous axr6 mutants is disrupted by aberrant patterns of cell division, leading to defects in the cells of the suspensor, root and hypocotyl precursors, and provasculature. The homozygous axr6 mutants arrest growth soon after germination lacking a root and hypocotyl and with severe vascular pattern defects in their cotyledons. Whereas previously described mutants with similar developmental defects are completely recessive, axr6 heterozygotes display a variety of morphological and physiological alterations that are most consistent with a defect in auxin physiology or response. The AXR6 gene is likely to be important for auxin response throughout the plant, including early development. 相似文献