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  • 11
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The principal constituent of amyloid plaques found in the brains of individuals with Alzheimer's disease (AD) is a 39–42-amino-acid protein, amyloid β protein (Aβ). This study examined whether the measurement of Aβ levels in CSF has diagnostic value. There were 108 subjects enrolled in this prospective study: AD (n = 39), non-AD controls (dementing diseases/syndromes; n = 20), and other (n = 49). CSF was obtained by lumbar puncture, and Aβ concentrations were determined using a dual monoclonal antibody immunoradiometric sandwich assay. The mean Aβ value for the AD group (15.9 ± 6.8 ng/ml) was not significantly different from that for the non-AD control group (13.0 ± 7.1 ng/ml; p = 0.07), and substantial overlap in results were observed. Aβ values did not correlate with age (r = −0.05, p = 0.59), severity of cognitive impairment (r = 0.22, p = 0.21), or duration of AD symptoms (r = 0.14, p = 0.45). These findings are in conflict with other reports in the literature; discrepant results could be due to the instability of Aβ in CSF. Aβ immunoreactivity decays rapidly under certain conditions, particularly multiple freeze/thaw cycles. Use of a stabilizing sample treatment buffer at the time of lumbar puncture allows storage of CSF without loss of Aβ reactivity. In conclusion, the total CSF Aβ level is not a useful marker for current diagnosis of AD.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 86 (2003), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Deagglomeration of ceramic powders is usually accomplished by immersion of powders in a surfactant-containing liquid vehicle, followed by milling. We seek alternative mechanisms to the classical milling approach by generating a chemical pressure to break up the agglomerate. This study explores the enhanced redispersion of TiO2 ceramic compacts that contain a nonionic water-soluble polymer, poly(ethylene glycol) (PEG). PEG forms a polymer solution within the agglomerated structure during redispersion. The resulting osmotic pressure gradient forces water into the porous structure and creates a tensile stress on the particle network with magnitudes as high as 0.6 MPa. Thus, the principle to achieving redispersion is to develop osmotic pressures that exceed the cohesive strength of the agglomerated structure. A critical PEG concentration of 2.0 vol% PEG 400 with respect to titania has been determined, below which redispersion is minimal.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Members of the newly discovered regulator of G protein signaling (RGS) families of proteins have a common RGS domain. This RGS domain is necessary for conferring upon RGS proteins the capacity to regulate negatively a variety of Gα protein subunits. However, RGS proteins are more than simply negative regulators of signaling. RGS proteins can function as effector antagonists, and recent evidence suggests that RGS proteins can have positive effects on signaling as well. Many RGS proteins possess additional C- and N-terminal modular protein-binding domains and motifs. The presence of these additional modules within the RGS proteins provides for multiple novel regulatory interactions performed by these molecules. These regions are involved in conferring regulatory selectivity to specific Gα-coupled signaling pathways, enhancing the efficacy of the RGS domain, and the translocation or targeting of RGS proteins to intracellular membranes. In other instances, these domains are involved in cross-talk between different Gα-coupled signaling pathways and, in some cases, likely serve to integrate small GTPases with these G protein signaling pathways. This review discusses these C- and N-terminal domains and their roles in the biology of the brain-enriched RGS proteins. Methods that can be used to investigate the function of these domains are also discussed.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: This study examined mRNAs encoding regulators of G protein signaling (RGSs) expressed within the striatum and determined whether their expression in the caudate putamen was altered by amphetamine. RT-PCR techniques were used to clone cDNA probes of RGSs expressed within the rat striatum. Northern blot analysis of caudate putamen and nucleus accumbens RNA determined the relative abundance of RGS mRNA expressed within the caudate putamen and adjacent nucleus accumbens to be RGS 2 〉 RGS 5 〉 RGS 16 〉 RGS 4 = RGS 9 〉 RGS 8 = RGS 3. A single injection of amphetamine rapidly and transiently induced RGS 2 mRNA. The temporal pattern of induction of RGS 2 strongly resembled that of the immediate early gene c-fos. Levels of mRNAs of RGS 3 and 5 steadily increased over a 4-h interval, as did that of the 6.6-kb transcript of RGS 8. The level of RGS 9 mRNA, which shows strong striatal-specific expression, steadily decreased over a 4-h interval, whereas RGS 4 and 16 and the 3.9-kb transcript of RGS 8 were not significantly affected at any point examined. The ability of amphetamine to alter RGS mRNA expression within the caudate putamen suggests these proteins may play an important role in adaptive processes to psychostimulant exposure.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 16 (2000), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Land disposal of sewage sludge in the UK is set to increase markedly in the next few years and much of this will be applied to grassland. Here we applied high rates of digested sludge cake (1–1.5×103 kg total N ha−1) to grassland and incorporated it prior to reseeding. Using automated chambers, nitrous oxide (N2O) and carbon dioxide (CO2) fluxes from the soil were monitored 2–4 times per day, for 6 months after sludge incorporation. Peaks of N2O emission were up to 1.4 kg N ha−1 d−1 soon after incorporation, and thereafter were regularly detected following significant rainfalls. Gas emissions reflected diurnal temperature variations, though N2O emissions were also strongly affected by rainfall. Although emissions decreased in the winter, temperatures below 4 °C stimulated short, sharp fluxes of both CO2 and N2O as temperature increased. The aggregate loss of nitrogen and carbon over the measurement period was up to 23 kg N ha−1 and 5.1 t C ha−1. Losses of N2O in the sludge-amended soil were associated with good microbial conditions for N mineralization, and with high carbon and water contents. Since grassland is an important source of greenhouse gases, application of sewage sludge can be at least as significant as fertilizer in enhancing these emissions.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 20 (2004), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Grassland is a major source of nitrous oxide (N2O) and methane (CH4) emissions in the UK, resulting from high rates of fertilizer application. We studied the effects of substituting mineral fertilizer by organic manures and a slow-release fertilizer in silage grass production on greenhouse gas emissions and soil mineral N content in a three-year field experiment. The organic manures investigated were sewage sludge pellets and composted sewage sludge (dry materials), and digested sewage sludge and cattle slurry (liquid materials). The organic manures produced N2O and carbon dioxide (CO2) consistently from time of application up to harvest. However, they mitigated N2O emissions by around 90% when aggregate emissions of 15.7 kg N ha−1 from NPK fertilizer were caused by a flux of up to 4.9 kg N ha−1 d−1 during the first 4 days after heavy rainfall subsequent to the NPK fertilizer application. CH4 was emitted only for 2 or 3 days after application of the liquid manures. CH4 and CO2 fluxes were not significantly mitigated. Composting and dried pellets were useful methods of conserving nutrients in organic wastes, enabling slow and sustained release of nitrogen. NPK slow-release fertilizer also maintained grass yields and was the most effective substitute for the conventional NPK fertilizer for mitigation of N2O fluxes.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Journal of neurochemistry 72 (1999), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Single injections of cocaine, amphetamine, or methamphetamine increased RGS2 mRNA levels in rat striatum by two- to fourfold. The D1 dopamine receptor-selective antagonist SCH-23390 had no effect by itself but strongly attenuated RGS2 mRNA induction by amphetamine. In contrast, the D2 receptor-selective antagonist raclopride induced RGS2 mRNA when administered alone and greatly enhanced stimulation by amphetamine. To examine the effects of repeated amphetamine on RGS2 expression, rats were treated with escalating doses of amphetamine (1.0-7.5 mg/kg) for 4 days, followed by 8 days of multiple daily injections (7.5 mg/kg/2 h × four injections). Twenty hours after the last injection the animals were challenged with amphetamine (7.5 mg/kg) or vehicle and killed 1 h later. In drug-naive animals, acute amphetamine induced the expression of RGS2, 3, and 5 and the immediate early genes c-fos and zif/268. RGS4 mRNA levels were not affected. Prior repeated treatment with amphetamine strongly suppressed induction of immediate early genes and RGS5 to a challenge dose of amphetamine. In sharp contrast, prior exposure to amphetamine did not reduce the induction of RGS2 and RGS3 mRNAs to a challenge dose of amphetamine, indicating that control of these genes is resistant to amphetamine-induced tolerance. These data establish a role for dopamine receptors in the regulation of RGS2 expression and suggest that RGS2 and 3 might mediate some aspects of amphetamine-induced tolerance.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 14 (1998), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 52 (2001), S. 0 
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Methods  of determining exchangeable K+ of soil by mixing extracting solutions and analysing the soil suspension with ion-selective electrodes were developed and evaluated on 30 samples of soils. From preliminary comparisons of the K+ extracted by BaCl2 and NH4OAc solutions and by batch and leaching treatments of soils, we established that suspensions of 5 g soil in 100 ml 0.5 m BaCl2 and single batch treatments of 1 h should be used. The exchangeable K+ was determined with a K-selective, valinomycin-based PVC membrane electrode and electrochemical cells that did or did not include a liquid junction (the reference electrode being a double-junction reference electrode assembly with a 10 m LiOAc salt bridge solution or a Cl-selective electrode, respectively). The Ba-exchangeable K+ values were sensibly the same whether a liquid junction was involved or not, a result that can be attributed to the beneficial effects of the salt bridge and the ionic strength of the extractant. Comparisons of these Ba-exchangeable results with those obtained by various combinations of batch or leaching treatments, BaCl2 or NH4OAc extractants and filtrate analysis by the ion-selective electrode method or atomic absorption spectrometry showed they were all highly correlated (r≥ 0.996). The selectivity of the K+-selective electrode (kpotKNH4 = 0.004) significantly reduced the interference from indigenous soil NH4+ in the BaCl2 suspensions. Overall, the results show potentiometric measurements of K+ in soil suspensions can provide a simple, rapid, and reliable means of determining exchangeable K+ in soils.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 93 (1971), S. 3534-3536 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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