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Objective To evaluate the ability of matrix-assisted laser desorption/ionization time-offlight mass spectrometry (MALDI-TOF MS) in identifying species of Acinetobacter calcoaceticus-Acinetobacter baumannii complex,and investigate the species distribution of Acinetobacter calcoaceticus-Acinetobacter baumannii complex isolated in our hospital.Methods A total of 502 nonduplicate clinical isolates of Acinetobacter calcoaceticus-Acinetobacter baumannii complex were retrospectively collected from the second affiliated hospital of Zhejiang University between January 2012 and July 2012.All strains were re-identified by MALDI-TOF MS and were also verified by sequence analysis of 16S-23S rRNA gene spacer region.Results Among all the 502 strains of Acinetobacter calcoaceticus-Acinetobacter baumannii complex,identificaion results provided by MALDI-TOF MS were A.baumannii (431,85.9％),A.pittii (68,13.5％),A.calcoaceticus (3,0.6％).Sequence analysis of 16S-23S rRNA gene spacer region was used to identify all the 502 strains:403 (80.3％) were identified as A.baumannii,68 (13.5％) as A.pittii,28 (5.6％) as A.nosocomialis and 3 (0.6％) as A.calcoaceticus.MALDI-TOF MS correctly identified all the strains but erroneously identified all 28 strains of A.nosocomialis as A.baumannii,compared with sequence analysis of 16S-23S rRNA gene spacer region.Conclusions MALDI-TOF MS can be used as a fast,simple,reliable and excellently reproducible method to identify members of Acinetobacter calcoaceticus-Acinetobacter baumannii complex at low costs.MALDI-TOF MS is expected to be an ideal technique for routine clinical microbiology testing in the future.
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markers of endometriosis. Its clinical value deserves further investigation.
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Objective To analyze the differential expression of proteins among patients with pancreatic cancer,chronic pancreatitis and choledocholithiasis in order to find potential biomarkers for diagnosis of pancreatic cancer and to differentiate pancreatic cancer from chronic pancreatitis. Methods The pancreatic juice were connected from 5 pancreatic cancer patients,6 chronic pancreatitis patients and 3 choledocholi-thiasis patients by naso-pancreatic drainage using endoscopic retrograde cholanglopancreatography(ERCP).The proteins in pooled pancreatic juice were separated by two-dimensional gel electrophoresis (2-DE).The differential expression of proteins were analyzed by image analysis software and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF-MS).Results ①There were 35-200 ml of pancreatic juice collected,and protein concentration were ranged from 0.8 to 4.6 μg/μl.The 2-DE showed that the protein spots in pancreatic cancer,chronic pancreatitis and choledocholithiasis juice were 196±12,209±15 and 199±10,respectively.The matched proteins among three groups all exceeded 75%.②MALDI-TOF-MS revealed that the expression of chain A of a covalent dimer of transthyretin in pancreatic cancer was up-regulated(＞2-fold)while the expressions of chain A of crystal structure of lipid-free human apolipoproteinA-1,chain of human lithostathin and regenerating islet-derived 1 beta precursor were down-regulated. Conclusions Protein spectra are different in patients with pancreatic cancer,chronic pancreatitis and choledocholithiasis.Transthyretin,apolipoproteinA-1,human lithostathin and regenerating islet-derived 1 beta might be the biomarkers of human pancreatic cancer and may be useful in distinguishing pancreatic cancer from chronic panceatitis.