Ricin is a plant toxin isolated from the seed of the castor plant(Ricinus communis). As a typical II ribosome inactivating protein,ricin consists of two polypeptide chains named ricin toxin A chain(RTA)and ricin toxin B chain(RTB),linked via a disulfide bridge. RTB binds to both glycopro?tein and glycolipid at the surface of the target cell and mediates ricin to be endocytosed and transported retro?gradely to the endoplasmic reticulum. After being reduced and retrotranslocated to the cytosol,RTA mediates its toxicity due to its activity of a RNA N- glycosidases. Aside from its main toxic effect of protein synthesis inhibition,ricin also displays other properties that contribute to its toxicity such as inducing apoptosis,cytokine secreting and peroxidation. Ricin is stable and can be easily isolated. It has many routes of intoxication with no specific antidotes. Due to its natural abundance,remarkable toxicity,and the potential to be used in biological warfare as well as terrorist attacks,ricin has been classified as a Category B biothreat agent. Here we reviewed its history as a biothreat agent,constitu?tion,intoxication mechanism,detection methods and the development of specific antitodes.

Objective:To analyze the immunogenicity of the extracellular region of Δ42PD1.Methods: Six fragments ofΔ42PD1 extracellular region-encoding sequence were amplified by PCR, and were cloned into pCTCON2 vector, a yeast surface displaying vector.Yeast cells were transfected with Δ42PD1 fragment-carrying plasmids, then yeast cells were spread on SDCAA plates.Single cell clones were selected and cultured in SGCAA media to induce expression of the target genes.Mouse anti-humanΔ42PD1 anti-serum were generated by immunization of BALB/c mice via intramuscular injection ofΔ42PD1-carrying plasmid plus in-situ electroporation.The binding of anti-serum with yeast cells surface-displaying Δ42PD1 fragments were analyzed using flowcytometry.Results:Nucleotide sequences analysis indicated that the amplified six fragments ofΔ42PD1 sequence length were 110 bp,and the isolated sequence ofΔ42PD1 fragments were 100%homology with PD1 gene previously registered in GenBank.Results from flowcytometry showed that among the six fragments of Δ42PD1 displaying on the surface of yeast cells,F3 and F2 profoundly boundΔ42PD1-specific polyclonal antibodies.Conclusion:F3 and F2 ofΔ42PD1 is an immunogenic dominant region,which pave the way for generation of Δ42PD1-specific monoclonal antibody and epitope mapping.

Public hospitals stand in need of strengthening cost control and improving operational efficiency to balance public welfare and economic benefits.Taking practice and exploration of ultrasound department as an exam-ple,it integrates the advantages of TDABC with cost management.Take the merits of time driver and activity driver,realizes direct cost accounting under the clinical pathway,strengthen capacity management capabilities un-der the integration of industry and finance,with a view to providing a powerful cost control tool for public hospitals to sensibly respond to pricing reform and reasonably make operational decisions.