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In this study, a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method coupled with UPLC-QqQ-MS/MS analysis was developed to detect tebuthiuron in sugarcane fields and the surrounding aquatic ecosystems. Methodological validation showed the method developed was of favorable sensitivity, reproducibility and accuracy. For assessment of its dietary and ecological risks, dissipation and occurrence of tebuthiuron in situ were further investigated through a supervised field trial and an aquatic environment monitoring carried out in six dominant sugarcane production regions in South China. After application at the range of recommended dose, tebuthiuron dominantly distributed in soil, and then dissipated in accordance with the first-order rate model with the half-lives of 12.2–21.5 d. At pre-harvest intervals (PHI), occurrence of tebuthiuron was found to be 0.718–1.366 mg/kg and 0.016–0.034 mg/kg, in sugarcane and soil, respectively. The supervised trials median residue (STMR) of tebuthiuron in sugarcane was thus 0.024 mg/kg and the dietary Risk Quotient (RQ d ) was accordingly calculated as 2.34 × 10 −4 , indicating safety on long-term consumption of sugarcane with tebuthiuron residues. Yet high risks of tebuthiuron towards soil ecosystems was noticed as it possessed maximum ecological Risk Quotient (RQ e ) at 1.97 to earthworms. In sugarcane field-surrounding aquatic environment, distribution of tebuthiuron was found to range from 0.007 mg/L to 0.022 mg/L, leading to high risk towards the aquatic ecosystem due to the maximum RQ e at 440 to algae, irrespective of its low risks to invertebrate and fish. Taken together, our approach serve as an effective tool for monitoring residual tebuthiuron environmentally and also advance in-depth understanding of dietary and ecological risks posed by the phenylurea herbicide. [ABSTRACT FROM AUTHOR]

Malignancy arising in fibrous dysplasia (FD) is rare. Approximately 100 cases have been reported so far, and osteosarcoma is the most common malignancy. We report a case of osteosarcoma in a 33-year-old Japanese man with monostotic FD of the right proximal femur from the age of 16 years. Histologically, relatively well-differentiated osteosarcoma was found in the FD lesion. Immunohistochemically, the FD was negative for p53 or MDM2, and the MIB-1 index was less than 1%, whereas the osteosarcoma was positive for both p53 and MDM2, and the MIB-1 index was up to 15%. The FD and osteosarcoma were negative for CDK4. Fluorescent in situ hybridization assay showed no amplification of the MDM2 gene, indicating that the osteosarcoma was a conventional osteosarcoma, not an intraosseous well-differentiated type. The original cell of malignancy in FD is unclear. Malignancy can be potentially derived from dysplastic cells in the area of the FD or cells in the adjacent normal tissues. GNAS gene mutation has recently been reported for fibrous dysplasia and the mutation is highly specific to fibrous dysplasia among fibro-osseous lesions including osteosarcoma. In this case, point mutations of GNAS were found in the FD and osteosarcoma but not in the adjacent normal tissues, suggesting that osteosarcoma was derived from the spindle cells of FD. This is the first report to clearly show that osteosarcoma is derived from the spindle cells in fibrous dysplasia (FD). [ABSTRACT FROM AUTHOR]