The effect of total particulate matter (TPM) from cigarette smoke on the expression and binding properties of nicotinic acetylcholine receptors (nAChRs) was investigated using a human neuroblastoma cell line (SH-SY5Y). TPM but not nicotine on its own inhibited cell growth at nicotine concentrations above 5 microM. To examine effects on nAChR expression, intact cells were incubated with 3H-epibatidine, and a Bmax of 13 fmoles/10(5) cells (7.8 x 10(4) binding sites/cell) was measured in unexposed cells as well as in cells treated with 2 microM nicotine alone or with TPM containing 2 microM nicotine. Using Scatchard analysis, we measured a Kd of 0.3 nM for 3H-epibatidine binding to nAChRs. This Kd was increased to 1.3 nM by addition of nicotine or TPM extract, both at 2 microM nicotine. Bmax, however, was unaffected, suggesting competitive binding of nicotine to its receptor. Short-term and prolonged 3-day exposures of SH-SY5Y cells to either TPM or nicotine at nicotine concentrations ranging from 0.2 microM to 20 microM increased specific binding, suggesting upregulation of nAChR expression. Most significant, binding was consistently greater in cells pretreated with TPM than in cells pretreated with nicotine. We conclude that TPM contains compounds that are toxic to cells at high concentrations (cell growth inhibition) but that do not compete with nicotine for binding to nAChRs (Scatchard analysis). These non-nicotinic compounds are capable of increasing the expression of one or more of the nAChR subunits. Furthermore, our cell culture assay provides a useful in vitro model for assessing the relative addictiveness of different tobacco products, including that of non-nicotine components.

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Aims:  This study investigated the survival of Escherichia coli and Salmonella spp. in sewage sludge applied to young and old Pinus radiata forest in Spring and Autumn/Winter. Methods and Results:  Large numbers of E. coli were present in sludge applied to the forest blocks but Salmonella spp. numbers were low or nondetectable. In the mature stand in Spring, numbers of E. coli returned to back‐ground after 3 weeks and die‐off was significantly correlated with per cent solids of sludge. E. coli survived longer in mature and young stands in Autumn/Winter where numbers did not significantly decrease until weeks 5 and 13, respectively. Salmonella spp. was detectable in the mature stand until week 4 and in the young stand until week 11 in Autumn/Winter. Conclusions:  Microbial die‐off was related to desiccation of the sewage sludge, and was faster in warmer, drier conditions. Significance and Impact of the Study:  In many countries, environmental and health risks associated with the application of sewage sludge to land are minimized by ‘best management practice’ guidelines, where risks are managed by restriction of public access to these sites. This study provides supporting evidence that withholding periods of greater than 6 months are sufficient to reduce microbial contaminants to background levels.

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This study determined whether human pathogenic viruses are present in two New Zealand surface waters that are used as drinking-water sources. Enteric viruses were concentrated using hollow-fibre ultrafiltration and detected using PCR for adenovirus (AdV), and reverse transcription PCR for norovirus (NOV) genogroups I-III, enterovirus, rotavirus (RoV) and hepatitis E virus (HEV). Target viruses were detected in 106/109 (97%) samples, with 67/109 (61%) samples positive for three or more viral types at any one time. AdV, NoV and ROV were detected the most frequently, and HEV the least frequently. Human NoV was not usually associated with animal NOV. Our results suggest that New Zealand would be well served by assessing the ability of drinking-water treatment plants to remove viruses from the source waters, and that this assessment could be based on the viral concentration of AdV-NoV-RoV. The long-term aim of our work is to use this information to estimate the risk of waterborne viral infection.

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