ABSTRACT
Objective To establish a human colon cancer cell line HCT-116/5-FU resistant to 5-fluorouracil(5-FU)and explore the relationship between runt-related transcription factor 3(RUNX3)and drug resistance of colorectal cancer.Methods The human colon cancer cell line HCT-116/5-FU with resistance to 5-FU was established by low concentration gradient increment combined with high-dose intermittent shock.CCK-8 method was used to determine the half maximal inhibitory concentration(IC
Subject(s)
Humans , Cell Line, Tumor , Colonic Neoplasms/genetics , Core Binding Factor Alpha 3 Subunit , Drug Resistance, Neoplasm , Fluorouracil/pharmacology , Transcription Factor 3ABSTRACT
Objective To screen specific mass peaks (SMP) of carbapenem-resistant Klebsiella pneumoniae (CRKP) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and perform rapid homology analysis on CRKP based on SMP.Methods 76 strains of CRKP with multilocus sequence typing (MLST) were selected from a microbiology laboratory of a hospital, 52 strains were for establishment of method and 24 strains were for validation of method. Five different criteria for selecting SMP of CRKP were set, SMP of different ST-type were screened according to different criteria, CRKP was typed based on screened SMP, criterion with the highest coincidence rate of MLST results was determined as the best criterion. Twenty-four CRKP strains were typed according to the specific peaks screened through best criteria, accuracy of SMP typing method was verified, and was compared with principal component analysis (PCA) and main spectra profile (MSP) cluster analysis in mass spectrometer software.Results According to standard 2 (①signal-to-noise ratio [S/N]≥4, ②S/N ratio≥1.5, ③coefficient of variability [CV≤40％]), 45 SMP were selected from 52 strains of CRKP strains, 29 strains of CRKP were typed by SMP, with the highest coincidence rate (82.8％) with MLST, which was determined as the best criterion. Another 24 CRKP strains were typed according to SMP screened based on this criterion, and the coincidence rate with MLST was 83.3％. The coincidence rate between PCA cluster analysis and MLST was only 66.7％, consistency between MSP clustering analysis and MLST was poor, and it didn't conform to the grouping trend of ST typing.Conclusion MALDI-TOF MS can select SMP of CRKP of different ST, which can be used for rapid homology analysis on CRKP, provide basis for surveillance and control of outbreak of healthcare-associated infection.
ABSTRACT
Using MRS medium, as imitating gastroenteric environments, such as low pH (1.5-4.5) and high bile salt (0.1%~0.4%), the antagonistic properties of Lactobacillus acidophilus were studied. At the same time, the antimicrobial activities on pathogenic E. coli and S. aureus in the intestinal tract and antibiotic tolerance of Lacto-bacillus acidophilus were also studied. The results indicated that Lactobacillus acidophilus survived at pH 2.5 - 4.5 after 6h culture and the living bacterial number could reach 107cfu/mL. One strain even survived at pH 1.5; that living bacterial number were above 106cfu/mL at the 0.1% -0.3% bile salt and a strain survived in 0.4% after 4h culture; that antimicrobial activities to the pathogenic E. coli and 5. aureus were obvious; and that the tolerance to Penicillin and Roxithromycin was medium and power.