Immunocapture-based fluorometric assay for the measurement of neprilysin-specific enzyme activity in brain tissue homogenates and cerebrospinal fluid.

Contains fulltext : 69861.pdf (publisher's version ) (Closed access)Neprilysin, a zinc-metalloendopeptidase, has important roles in the physiology and pathology of many diseases such as hypertension, cancer and Alzheimer's disease. We have developed an immunocapture assay to measure the specific enzyme activity of neprilysin in brain tissue homogenates and cerebrospinal fluid (CSF). The assay uses a neprilysin-specific antibody, previously used in a commercially available ELISA kit, to isolate and immobilise NEP from brain homogenates and CSF, prior to the addition of a fluorogenic peptide substrate (Mca-RPPGFSAFK(Dnp)). This fluorogenic substrate is ordinarily cleaved by multiple enzymes. We have shown that without the immunocapture phase, even under reaction conditions reported to be specific for neprilysin - i.e. in the presence of thiorphan, at pH above 7 - the fluorogenic peptide substrate does not allow neprilysin activity in brain homogenates and CSF to be discriminated from that of other closely related enzymes. The specificity of the immunocapture enzyme activity assay was confirmed by >80% inhibition of substrate cleavage in brain homogenates and CSF in the presence of thiorphan. The assay allows high-throughput analysis and, critically, also ensures a high level of enzyme specificity even when assaying crude tissue homogenates or CSF

Effects of heavy metal pollution in the Pilcomayo river system, Bolivia, on resident human populations

The Pilcomayo river in Bolivia drains the Potosi mining district and flows downstream, exposing indigenous populations, who rely on the river for drinking water, irrigation and fish, to elevated levels of toxic metals. A preliminary analysis of agricultural soil and crops from four riverside Pilcomayo communities has shown that many agricultural fields are contaminated with heavy metals (Ag, Cd, Cu, Pb, Sb, Zn) and arsenic (As) However, concentrations of these elements in most crops are within guideline values. Concentrations of metals and As in samples of drinking water are, for the most part, lower than concentrations in Pilcomayo river water taken at the respective communities, and the drinking water concentrations are within guideline values. Exceptions are Sb and As concentrations in two of the communities. In irrigation waters, Zn and Pb exceed recommended guideline values in two of the communities, and may lead to high Zn and Pb values in some crops and soils. The work carried out to date suggests that the strategies used by these communities appear to considerably reduce their risks to exposure. Work is ongoing to develop more complex and effective strategies based on further geochemical analyses and social science surveys.

Hong Kong identity and the press–politics dynamics: a corpus-assisted discourse study

This is an Author's Original Manuscript of an article submitted for consideration in the Asian Journal of Communication [Taylor and Francis © AMIC/SCI-NTU]. Asian Journal of Communication is available online at http://www.tandfonline.com/ and the definitive version is available at: http://dx.doi.org/10.1080/01292986.2012.701315This article uses corpus-assisted discourse studies to examine the discursive construction of collective identity in the Hong Kong press, particularly with regard to its relationship with mainland China. Drawing on critical discourse analysis and collective identity theory, it develops a set of analytical techniques amenable to quantification, and applies it to a corpus of newspaper coverage of the 2005 Hong Kong Chief Executive election. The article uses these techniques not only to develop a representative description and interpretation of discursive patterns, but also to offer an explanatory account of the discursive construction of Hong Kong identity. It shows that the discursive patterns vary systematically depending on newspaper ownership, commercial imperatives, and newspaper type