[Analysis of soil components along water channel of east route of South-to-North Water Diversion Project].

OBJECTIVE: To explore the relationship between the soil components along the areas of the east route of the Southto-North Water Diversion Project and the survival situation of Oncomelania hupensis snails. METHODS: Four study sites were selected along the project, and soil samples were collected to analyze the components. The amounts of components among the different study sites were compared statistically. RESULTS: Except zinc, sodium, and phosphorus, the contents of the soil components where the snails survived were different from those where snails were dead (t = -19.150 to 12.810, all P < 0.01). However, the logistic regression analysis did not obtain a model with statistical significance. CONCLUSIONS: O. hupensis snails live in the soil with adequate organic matter and neutral pH value. Along with the global warming and the operation of the South-toNorth Water Diversion Project, O. hupensis snails may survive in the northern area, and therefore, the surveillance work should be strengthened.

Dexamethasone enhances invasiveness of Aspergillus fumigatus conidia and fibronectin expression in A549 cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The efficacies of current treatments for invasive aspergillus (IA) are unsatisfactory and new therapeutic targets or regimens to treat IA are urgently needed. Previous studies have indicated that the ability of conidia to invade host cells is critical in IA development and fibronectin has a hand in the conidia adherence process. In the clinical setting, many patients who receive glucocorticoid for extended periods are susceptible to Aspergillus fumigatus (A. fumigatus) infection, for this reason we investigated the effect of glucocorticoid on conidia invasiveness by comparing the invasiveness of A. fumigatus conidia in the type II human alveolar cell line (A549) cultured with different concentrations of dexamethasone. We also explored the relationships between dexamethasone and fibronectin expression.</p><p><b>METHODS</b>Following culture with anti-fibronectin antibodies and/or dexamethasone, type II human alveolar A549 cells were infected with conidia of A. fumigatus. After 4 hours, the extracellular free conidia were washed away and the remaining immobilized conidia were released using Triton-X 100 and quantified by counting the colony-forming units. The invasiveness of conidia was measured by calculating the invasion rate (%). The transcription of the fibronectin gene in cells cultured with different concentrations of dexamethasone for 24 hours was tested by fluorogenic quantitative RT-PCR while the expression of fibronectinin cells cultured for 48 hours was tested by Western blotting and immunocytochemistry.</p><p><b>RESULTS</b>A significant reduction in the invasiveness of conidia was seen in the cells cultured with anti-fibronectin antibody ((14.42 ± 1.68)% vs. (19.17 ± 2.53)%, P < 0.05), but no significant difference was observed in cells cultured with a combination of anti-fibronectin antibody and dexamethasone (6.37 ± 10(-5) mol/L). There was no correlation between the dexamethasone concentration and the invasiveness of conidia after dexamethasone pretreatment of cells for 4 hours. In contrast, after pretreated for 24 hours, the invasiveness of conidia in the presence of 6.37×10(-5) mol/L dexamethasone ((24.66 ± 2.41)%) was higher than for the control ((19.17 ± 2.53)%) and the 0.25×10(-5) mol/L group ((19.93 ± 3.06)%), and the invasiveness in the 1.27×10(-5) mol/L group ((22.47 ± 2.46)%) was also higher than in the control, P < 0.05. The relative transcripts of the fibronectin gene after exposure to 6.37×10(-5) mol/L dexamethasone (9.19×10(-3)±1.2×10(-3)) was higher than for the control (4.61×10(-3)± 1.54×10(-3)) and the 0.25×10(-5) mol/L group (6.20×10(-3)± 1.93×10(-3)), and expression in the 1.27×10(-5) mol/L group (7.94×10(-3)± 2.24×10(-3)) was also higher than for the control, P < 0.05. High concentrations of dexamethasone promoted fibronectin production after culture for 48 hours.</p><p><b>CONCLUSIONS</b>Dexamethasone can increase invasiveness of A. fumigatus conidia by promoting fibronectin expression. This may partially explain why patients who are given large doses of glucocorticoids for extended periods are more susceptible to A. fumigatus infection.</p>