Quantitative analysis of chloramphenicol, thiamphenicol, florfenicol and florfenicol amine in eggs via liquid chromatography-electrospray ionization tandem mass spectrometry.

A widely applicable method involving liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (LC-ESI/MS/MS) was developed for the simultaneous determination of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in eggs. Samples were extracted with ethyl acetate-acetonitrile-ammonium hydroxide (49:49:2, v/v) and defatted with hexane saturated with acetonitrile. The analysis was carried out on a mass spectrometer via an electrospray interface operated in the positive and negative ionization modes using deuterated chloramphenicol-d5 as the internal standard. The limits of detection and limits of quantification were 0.04-0.5 µg/kg and 0.1-1.5 µg/kg in eggs, respectively. The average recoveries of the four analytes from egg samples were 90.84-108.23%, with relative standard deviations of less than 9.61%. The corresponding intra-day and inter-day variations were found to be less than 8.11% and 11.30%, respectively. Finally, the new approach was successfully applied to the quantitative determination of these analytes in 50 commercial eggs from local supermarkets.

Inhibition of DACH1 activity by short hairpin RNA represses cell proliferation and tumor invasion in pancreatic cancer.

Cancer of the pancreas is one of the most lethal diseases worldwide. Better understanding of the molecular mechanisms involved in tumorigenesis is of great consequence to elevate the survival rate. Human Dachshund homologue 1 (DACH1) plays a controversial role in human malignancy progression with its expression being altered in a variety of cancers. Nevertheless, its functional roles and molecular mechanisms in pancreatic cancer remain unknown. The expression of DACH1 in pancreatic cancer cell lines and the ductal epithelial cells were evaluated both at mRNA and protein levels. Three pairs of siRNA targeting the DACH1 gene were designed and synthesized, double-stranded short hairpin RNA (shRNA) were annealed and inserted into pGenesil-1 vector, which was confirmed by enzymatic digestion and sequencing analyses. The successfully constructed recombinant plasmids were transfected into Capan-1 cells and our data indicated that knockdown of DACH1 gene expression showed strong correlation with repressing tumorigenesis. The proliferation of Capan-1 cells was significantly repressed as evaluated by CCK-8 and colony formation assays. Flow cymetry revealed that cell apoptosis was promoted in interference plasmid group compared with control groups (P<0.05), whereas cell cycle had no significant differences among the groups (P>0.05). Transwell assay validated the abilities of migration and invasion as being significantly reduced in pshRNA-DACH1 group. Furthermore, our study suggested that DACH1 expression regulates the pancreatic cancer cell apoptosis through interacting with Bcl-2 signaling axis, whereas it controls cell migration and invasion via epithelial-mesenchymal transition (EMT) process.