OBJECTIVE： To compare the quality of ceftazidime for injection among the domestic and imported products METHODS： The ceftazidime was observed and determined with respect to the property， color and clarity of the solution， insoluble particle， content of pyridine， polymer of ceftazidime and marked content of ceftazidime RESULTS： There were some differences in above－ mentioned parameters among products of different factories， however， the parameters were within the range of standard CONCLUSION： The quality of domestic products is reliable and comparable to that of imported ones

Magnetotactic bacteria (MTB), a group of phylogenetically diverse organisms that use their unique intracellular magnetosome organelles to swim along the Earth's magnetic field, play important roles in the biogeochemical cycles of iron and sulfur. Previous studies have revealed that the bacterial actin protein MamK plays essential roles in the linear arrangement of magnetosomes in MTB cells belonging to the Proteobacteria phylum. However, the molecular mechanisms of multiple-magnetosome-chain arrangements in MTB remain largely unknown. Here, we report that the MamK filaments from the uncultivated 'Candidatus Magnetobacterium casensis' (Mcas) within the phylum Nitrospirae polymerized in the presence of ATP alone and were stable without obvious ATP hydrolysis-mediated disassembly. MamK in Mcas can convert NTP to NDP and NDP to NMP, showing the highest preference to ATP. Unlike its Magnetospirillum counterparts, which form a single magnetosome chain, or other bacterial actins such as MreB and ParM, the polymerized MamK from Mcas is independent of metal ions and nucleotides except for ATP, and is assembled into well-ordered filamentous bundles consisted of multiple filaments. Our results suggest a dynamically stable assembly of MamK from the uncultivated Nitrospirae MTB that synthesizes multiple magnetosome chains per cell. These findings further improve the current knowledge of biomineralization and organelle biogenesis in prokaryotic systems.
Actins ; chemistry ; metabolism ; Adenosine Triphosphate ; metabolism ; Bacteria ; classification ; metabolism ; Bacterial Proteins ; chemistry ; metabolism ; Magnetospirillum ; classification ; metabolism ; Nucleotides ; metabolism ; Phylogeny ; Substrate Specificity