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  • 2000-2004  (2)
  • 1995-1999  (2)
  • 1960-1964  (1)
  • 1955-1959  (2)
  • 1
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Urethral epithelial cells are invaded by Neisseria gonorrhoeae during gonococcal infection in men. To understand further the mechanisms of gonococcal entry into host cells, we used the primary human urethral epithelial cells (PHUECs) tissue culture system recently developed by our laboratory. These studies showed that human asialoglycoprotein receptor (ASGP-R) and the terminal lactosamine of lacto-N-neotetraose-expressing gonococcal lipooligosaccharide (LOS) play an important role in invasion of PHUECs. Microscopy studies showed that ASGP-R traffics to the cell surface after gonococcal challenge. Co-localization of ASGP-R with gonococci was observed. As ASGP-R-mediated endocytosis is clathrin dependent, clathrin localization in PHUECs was examined after infection. Infected PHUECs showed increased clathrin recruitment and co-localization of clathrin and gonococci. Preincubating PHUECs in 0.3 M sucrose or monodansylcadaverine (MDC), which both inhibit clathrin-coated pit formation, resulted in decreased invasion. N. gonorrhoeae strain 1291 produces a single LOS glycoform that terminates with Gal(β1–4)GlcNac(β1–3)Gal(β1–4)Glc (lacto-N-neotetraose). Invasion assays showed that strain 1291 invades significantly more than four isogenic mutants expressing truncated LOS. Sialylation of strain 1291 LOS inhibited invasion significantly. Preincubation of PHUECs in asialofetuin (ASF), an ASGP-R ligand, significantly reduced invasion. A dose–response reduction in invasion was observed in PHUECs preincubated with increasing concentrations of NaOH-deacylated 1291 LOS. These studies indicated that an interaction between lacto-N-neotetraose-terminal LOS and ASGP-R allows gonococcal entry into PHUECs.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In the present study, we show that Neisseria gonorrhoeae lipooligosaccharide (LOS) can bind to the asialoglycoprotein receptor (ASGP-R) on human sperm. This work demonstrates the presence of ASGP-R on human sperm. Binding of purified ASGP-R ligand decreased in the presence of gonococci. Binding of purified iodinated gonococcal LOS identified a protein of molecular weight corresponding to that of human ASGP-R. The presence of excess unlabelled LOS blocked binding of iodinated gonococcal LOS. Binding of wild-type gonococcal LOS to sperm was higher than that of mutant LOS lacking the galactose ligand for ASGP-R. These data suggest that the ASGP-R on human sperm cells recognizes and binds wild-type gonococcal LOS. This interaction may contribute to the transmission of gonorrhea from infected males to their sexual partners.
    Type of Medium: Electronic Resource
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  • 3
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    Sydney, N.S.W. : Periodicals Archive Online (PAO)
    Australasian Journal of Philosophy. 36 (1958) 46 
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  • 4
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    Unknown
    Sydney, N.S.W. : Periodicals Archive Online (PAO)
    Australasian Journal of Philosophy. 37 (1959) 242 
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  • 5
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    Philosophy 37 (1962), S. 263-268 
    ISSN: 0031-8191
    Source: Cambridge Journals Digital Archives
    Topics: Philosophy
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 42 (1995), S. 61-75 
    ISSN: 1573-0867
    Keywords: potentially mineralizable N ; CERES model ; LEACHM model ; fertilizer N requirements ; crop rotations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Quantification of N dynamics in the ecosystem has taken on major significance in today's society, for economic and environmental reasons. A major fraction of the available N in soils is derived from the mineralization of organic matter. For decades, scientists have attempted to quantify the rate at which soils mineralize N, but the complexity of the N cycle has made this a major task. Further, agronomists have long sought soil test methods that are practical, yet will provide accurate means of predicting the amounts and rates of release of N from soils. Such tests would allow us to make more precise fertilization decisions. This paper discusses the potentially mineralizable N concept, first promoted by Stanford and colleagues [61, 62, 64], and suggests how it may be incorporated into deterministic models, such as CERES and LEACHM, so as to provide more accurate estimates of N mineralization under field conditions. We also suggest how the potentially mineralizable N concept may be coupled to quick, routine laboratory methods of determining available soil N, such as the hot 2M KCl extracted NH4-N method recently developed by Gianello and Bremner [35], and used together with deterministic N models, such as CERES, for predicting probable fertilizer N requirements.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 42 (1995), S. 277-296 
    ISSN: 1573-0867
    Keywords: nutrient cycling ; socioeconomic constraints ; sustainable agriculture ; temperate/boreal ecosystems ; tropical ecosystem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper discusses the influence of N resources (fertilizer, legume, soil) on sustainable agriculture in temperate/boreal ecosystems (exemplified by the Canadian prairies), and in the humid, subhumid and semi-arid tropic (exemplified by southeast Asia and central and south America). A sustainable agricultural system is one that is economically viable, provides safe, nutritious food, and. conserves or enhances the environment. Consequently, we discuss the impact of N on crop yields, nitrogen use efficiency (NUE), food quality, environmental quality and on socioeconomic factors. Considerably more long-term research has been conducted in the temperate regions, consequently this was where most information was available. However, the principles governing the behaviour of N are very similar in all ecosystems. It is mainly the rates of nutrient cycling and the socioeconomic constraints that differ. Legumes and N fertilizers, used in a responsible manner, will increase crop production, provide quality food, increase net returns, reduce risk of monetary loss, improve soil quality, and reduce N loss via leaching and gaseous means. The key to sustainable management of N is to synchronize N supply with N use by the crop. Because societies in most temperate ecosystems are more affluent they are better positioned to encourage adoption of management techniques that promote sustainability. In contrast, most producers in the tropics are, subsistence farmers; consequently, their immediate goal is economic survival, not preservation of the environment.
    Type of Medium: Electronic Resource
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