Sulbactam enhances the in vitro activity of sitafloxacin against extensively-drug resistant Acinetobacter baumannii.

The present study aimed to determine the in vitro activities of sulbactam and sitafloxacin against extensively-drug resistant Acinetobacter baumannii (XDR-A. baumannii). A total of 50 strains of XDR-A. baumannii were isolated from clinical specimens. Broth microdilution assay was applied to determine the minimum inhibitory concentration (MIC) for sulbactam and sitafloxacin. Microdilution checkerboard method was used to determine the in vitro activity of this antimicrobial combination. Accordingly, the fractional inhibitory concentration (FIC) and FIC index (FICI) were calculated. Time-kill study was also carried out for four strains with different susceptibilities to determine the bactericidal activities of individual or combined use of sitafloxacin and sulbactam. Isolates with MICs of sitafloxacin ≤2 mg/l were considered to be susceptible to sitafloxacin. The susceptibility rate for sitafloxacin was 92% originally. When combined with sulbactam, this rate increased to 96%. Microdilution checkerboard results indicated that, when tested in combination, sulbactam/sitafloxacin exhibited marked synergistic and partial synergistic effects on 16 and 50% of the 50 strains, respectively. Time-kill assay suggested that sulbactam enhanced the bactericidal activity of sitafloxacin and the combination induced a synergistic effect. For strains that were not susceptible to sitafloxacin, the bactericidal activities of the combination of sitafloxacin and sulbactam at a sub-MIC concentration were impaired. However, this impairment could be overcome with the increase of the concentration to 1X MIC. The present study demonstrated that sulbactam enhanced the in vitro antimicrobial activity of sitafloxacin against XDR-A. baumannii.

The prevalence of Escherichia coli strains with extended spectrum beta-lactamases isolated in China.

The extended-spectrum-lactamases-producing Escherichia coli has rapidly spread worldwide. Escherichia coli has been becoming much more resistant to ß-lactam antibiotics and other commonly available antimicrobials. We investigated the prevalence, resistance, and probable gene type of extended spectrum beta-lactamases (ESBLs) using minimum inhibitory concentrations (MICs) testing and polymerase chain reaction (PCR). We have collected 289 single-patient E. coli Isolates based on samples of China from July 2013 to August 2014. This article explored that the prevalence of ESBL-producing Isolates showed multi-resistant to antimicrobials such as fluoroquinolones, trimethoprim, tetracycline and aminoglycosides, and so on. The frequencies of resistance in Isolates were as follows: Ciprofloxacin, 74%, gentamicin, 69.5%, levofloxacin, 63%, tobramycin, 39%, and minocycline, 7.9%. According to our results, 197(68.2%) of the total 289 Isolates were ESBL-producing strains; further, 172 (87.3%) producers contained genes encoding CTX-M enzymes and 142(72.1%) producers contained genes encoding TEM enzymes. Most ESBL-producing Escherichia coli has produced more than one type of ß-lactamase. Nucleotide sequence analysis has revealed the diversity of ESBLs types: CTX-M -15 is in the majority and TEM-135, CTX-M-3, CTX-M-98, CTX-M-14, CTX-M-142, CTX-M-65, CTX-M-55, CTX-M-27, and CTX-M-123 have been recovered. The results confirm that ESBL producers which are common in hospital strains of Escherichia coli are resistant to cephalosporins and other antibiotics in China. It is important to monitor such strains closely and provide scientific evidence of rational application of antibiotics to prevent their spread.

Overexpression of Abl2 predicts poor prognosis in hepatocellular carcinomas and is associated with cancer cell migration and invasion.

INTRODUCTION: Abl2 nonreceptor tyrosine kinase (Arg, c-abl oncogene 2) has recently been identified as being recurrently amplified at DNA levels and overexpressed at mRNA levels in hepatocellular carcinomas (HCCs), and might be a potential oncogenic driver and therapeutic target for HCC. METHODS: In this study, we investigated the Abl2 expression in a series of HCC tumors by immunohistochemistry and further evaluated its clinicopathological and prognostic significance. We also performed an in vitro experiment to validate the effect of Abl2 gene silencing on the migration and invasion abilities of human liver cancer HepG2 cells. RESULTS: It has been demonstrated that Abl2 was unregulated in 37.3% (28/75) of primary HCC tissues, and was significantly associated with a shorter overall survival time (P=0.0005). In addition, Abl2 gene silencing in HepG2 cells significantly attenuated its migration and invasion abilities in vitro. We also found that the phosphorylation of metastasis-associated gene cortactin was markedly decreased by Abl2 silencing. CONCLUSION: We propose that Abl2 might be a potential candidate therapeutic target for HCCs and that targeted therapies against Abl2 in the treatment of HCCs deserve further investigation in the future.

A study of mifepristone/IFN-γ-induced apoptosis of human cholangiocarcinoma cell line FRH-0201 in vitro.

OBJECTIVE: To investigate the effects of mifepristone, a progesterone receptor (PR) antagonist, through the proliferation of human cholangiocarcinoma cell line FRH-0201 in vitro and the possible mechanisms involved. METHODS: A two-step addition of poly-HRP anti-mouse immunoglobulin G detection system was used to detect the expression of PR in FRH-0201 cells. After treatments with various concentrations of mifepristone (10, 20, 40, 80, 160, and 320 µmol/L) at various time intervals (24, 48, and 72 hours), the rate of cell inhibition, the rate of cell apoptosis, and the expression of bax/bcl-2/Fas were analyzed with tetrazolium blue (MTT) assay, flow cytometry, reverse transcription polymerase chain reaction and Western blotting. The effect of mifepristone and mifepristone combined with interferon (IFN)-γ-inducing apoptosis on the cells was observed. RESULTS: Mifepristone remarkably inhibited the proliferation of FRH-0201 cells, which was revealed by MTT assay in a dose- and time-dependent manner. The inhibitory rate gradually increased following the increase of the dosage of mifepristone from a low dosage (10 µmol/L) to a high dosage (320 µmol/L) at different time intervals. Flow cytometry analysis showed mifepristone increased the rate of the FRH-0201 cell-line apoptosis. Notably, the rate of apoptosis increased markedly when the cells were pretreated with IFN-γ and then treated with mifepristone. In addition, mifepristone obviously upregulated bax and Fas expression and downregulated bcl-2 expression. CONCLUSION: Mifepristone effectively inhibited the growth of PR-positive human cholangiocarcinoma cell line FRH-0201 in vitro through multiple mechanisms. Mifepristone combined with IFN-γ might therefore induce the apoptosis of the cell line, which is possibly a beneficial clinical scheme for patients suffering from cholangiocarcinoma.

Hepatitis B virus infection and replication in human bone marrow mesenchymal stem cells.

BACKGROUND: Hepatitis B virus (HBV) infection is a blood borne infectious disease that affects the liver. Human bone marrow mesenchymal stem cells (BMSCs) may serve as a cell source for adult stem cell transplantation in liver repair. However, the susceptibility of human BMSCs to HBV infection is poorly understood. The aim of this study was to investigate the infection and replication of HBV in cultures of human BMSCs. RESULTS: Human BMSCs were confirmed using flow cytometry. Intracellular HBV DNA was detected at d 2 after infection and maintained at relatively high levels from d 6 to d 12. The maximal level of intracellular HBV DNA was 9.37 × 105 copies/mL. The extracellular HBV DNA was observed from d 3 to d 15, and the levels ranged from 3.792 × 102 copies/mL to 4.067 × 105 copies/mL. HBsAg in the culture medium was detected from d 2 to d 16. HBeAg secretion was positive from d 5 to d 13. HBcAg constantly showed positive signals in approximately 7%-20% of BMSCs from 2 days after exposure. Intracellular HBV covalently closed circular DNA (cccDNA) could be detected as early as 2 days postinfection, and strong signals were obtained with increasing time. CONCLUSION: HBV can infect and replicate in human BMSCs. Human BMSCs may be a useful tool for investigating HBV life-cycle and the mechanism of initial virus-cell interactions.

Antineoplastic effects of octreotide on human gallbladder cancer cells in vitro.

AIM: To investigate whether octreotide can inhibit the growth of human gallbladder cancer cells in vitro and to elucidate the antineoplastic mechanism of octreotide in gallbladder cancer. METHODS: A human gallbladder cancer cell line, GBC-SD, was cultured in vitro. The antiproliferative effects of octreotide were examined by means of an MTT assay and a colony forming ability assay. Morphological variation was investigated under scanning electron microscopy and transmission electron microscopy. Cell cycle analysis and apoptosis rate was evaluated by flow cytometry (FCM) after staining by propidium iodide. DNA fragmentation was assayed by agarose gel electrophoresis. Immunohistochemical staining was performed to evaluate the expressions of mutant-type p53 and bcl-2. RESULTS: The growth curve and colony forming ability assay showed significant inhibition of octreotide to the proliferation of GBC-SD cells in culture in a time- and dose-dependent manner. After exposure to octreotide, GBC-SD cells showed typically apoptotic characteristics, including morphological changes of chromatin condensation, vacuolar degeneration, nucleus fragmentation and apoptotic body formation. In FCM profile apoptotic cells showed increased sub-G(1) peaks in the octreotide group, significantly higher than the control group (P=0.013). There was also an augmentation in the cell proportion of G(0)/G(1) phase (P=0.015), while the proportion of S phase and G(2)/M phase remained unchanged (P=0.057 and P=0.280, respectively). DNA agarose gel electrophoresis displayed a ladder after exposure to 1 000 nmol/L octreotide. After being treated with octreotide, the expressions of both mutant-type p53 and bcl-2 decreased considering the percentage of positive cells (P<0.05). CONCLUSION: Octreotide has a negative action to the proliferation of GBC-SD cells, and the mechanism may be related to cytostatic and cytotoxic effects. The reduction of mutant-type p53 and bcl-2 expressions may be associated with the apoptosis induced by octreotide.