Diosgenin induces ROS-dependent autophagy and cytotoxicity via mTOR signaling pathway in chronic myeloid leukemia cells.

BACKGROUND: Diosgenin, a steroidal saponin isolated from legumes and yams, has been confirmed to possess potent anticancer effect on multifarious tumors including chronic myeloid leukemia (CML). PURPOSE: We aimed to further determine the anti-cancer activity of diosgenin and its mechanisms in CML cells. METHODS: The cell vitality was detected by MTT assay. Autophagic flux and reactive oxygen species (ROS) production were analyzed by laser scanning confocal microscope. Apoptosis was observed by flow cytometry. All proteins expression was examined by western blotting. RESULTS: Autophagy induction was demonstrated by examination of autophagic flux including autophagosomes accumulation, autophagosome-lysosome fusion and degradation of autophagosomes. Moreover, blocking autophagy with inhibitor chloroquine (CQ) and 3-methyladenine (3-MA), enhanced diosgenin-induced apoptosis, indicating the protective effect of autophagy in diosgenin-treated CML cells. Further study suggested that diosgenin-induced autophagy and cytotoxicity were accompanied by reactive oxygen species (ROS) generation and mammalian target of rapamycin (mTOR) signaling pathway inhibition. N-acetyl-L-cysteine (NAC) administration, a scavenger agent of ROS, could down-regulate diosgenin-induced autophagy via reversion of mTOR pathway inhibition. CONCLUSION: These results indicate that diosgenin obviously generates ROS and this oxidative pressure not only produces cytotoxic effect on CML cells but also induces autophagy. What's more, autophagy functions as a cytoprotective mechanism to overcome cytotoxicity of diosgenin in tumor cells and inhibition of autophagy can enhance the anti-CML activity of diosgenin.

Two novel Salmonella genomic island 1 variants in Proteus mirabilis isolates from swine farms in China.

Four different Salmonella genomic island 1 (SGI1) variants, including two novel variants, were characterized in one Salmonella enterica serovar Rissen sequence type ST1917 isolate and three Proteus mirabilis isolates from swine farms in China. One novel variant was derived from SGI1-B with the backbone gene S021 disrupted by a 12.72-kb IS26 composite transposon containing the dfrA17-aadA5 cassettes and macrolide inactivation gene cluster mphA-mrx-mphR. The other one was an integron-free SGI1 and contained a 183-bp truncated S025 next to IS6100 and S044.

First report of macrolide resistance gene erm(T) harbored by a novel small plasmid from Erysipelothrix rhusiopathiae.

The macrolide resistance gene erm(T) was identified for the first time in a porcine Erysipelothrix rhusiopathiae isolate from swine in China. The novel 3,749-bp small plasmid pER29, which carries erm(T), had a G+C content of 31% and four distinct open reading frames. The presence of pER29 increased by at least 128-fold the MICs of clindamycin and erythromycin for E. rhusiopathiae. The fitness cost of pER29 could be responsible for the low frequency of erm(T) in E. rhusiopathiae.

Molecular characteristics of Salmonella genomic island 1 in Proteus mirabilis isolates from poultry farms in China.

Six out of the 64 studied Proteus mirabilis isolates from 11 poultry farms in China contained Salmonella genomic island 1 (SGI1). PCR mapping showed that the complete nucleotide sequences of SGI1s ranged from 33.2 to 42.5 kb. Three novel variants, SGI1-W, SGI1-X, and SGI1-Y, have been characterized. Resistance genes lnuF, dfrA25, and qnrB2 were identified in SGI1 for the first time.

Dynamics of quinolone resistance in fecal Escherichia coli of finishing pigs after ciprofloxacin administration.

Escherichia coli resistance to quinolones has now become a serious issue in large-scale pig farms of China. It is necessary to study the dynamics of quinolone resistance in fecal Escherichia coli of pigs after antimicrobial administration. Here, we present the hypothesis that the emergence of resistance in pigs requires drug accumulation for 7 days or more. To test this hypothesis, 26 pigs (90 days old, about 30 kg) not fed any antimicrobial after weaning were selected and divided into 2 equal groups: the experimental (EP) group and control (CP) group. Pigs in the EP group were orally treated daily with 5 mg ciprofloxacin/kg of body weight for 30 days, and pigs in the CP group were fed a normal diet. Fresh feces were collected at 16 time points from day 0 to day 61. At each time point, ten E. coli clones were tested for susceptibility to quinolones and mutations of gyrA and parC. The results showed that the minimal inhibitory concentration (MIC) for ciprofloxacin increased 16-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin administration for 3 days and decreased 256-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin withdrawal for 26 days. GyrA (S83L, D87N/ D87Y) and parC (S80I) substitutions were observed in all quinolone-resistant E. coli (QREC) clones with an MIC ≥8 µg/ml. This study provides scientific theoretical guidance for the rational use of antimicrobials and the control of bacterial resistance.

Comparative dynamic distribution of avian infectious bronchitis virus M41, H120, and SAIBK strains by quantitative real-time RT-PCR in SPF chickens.

Avian infectious bronchitis is an acute, highly contagious disease of chickens. To study the differences of dynamic distribution between nephropathogenic infectious bronchitis virus (IBV) strains such as SAIBK and other strains (the M41 and H120 strains), relative quantitative real-time reverse transcription-polymerase chain reaction was developed by housekeeping gene selection. Glyceraldehyde-3-phosphate dehydrogenase and Ubiquitin were chosen for normalization in this experimental set. Then nine tissues, the trachea, thymus, liver, spleen, lungs, kidney, pancreas, proventriculus, and bursa of Fabricius, were analyzed and compared to determine the tropism of IBV infection. In this research, the kidney and the lung were established of the most sensitive organs in IBV infection. The pancreas and the liver are candidates for antigen detection. The trachea and the spleen can be used as references for histological diagnosis, but they are not suitable for antigen detection; proventriculus might be an important target in IBV infection; the thymus and the bursa of Fabricius were not sensitive organs in IBV infection.

Detection of clinically important ß-lactamases in commensal Escherichia coli of human and swine origin in western China.

Data correlating ß-lactamases found in commensal Escherichia coli of human and animal origin are limited. In this study, 447 commensal E. coli isolates from the faeces of humans and swine (280 human isolates from four hospitals and 167 swine isolates from seven farms) were collected between September 2006 and January 2009 in western China. For extended-spectrum ß-lactamase (ESBL)-producing and other cephalosporin-resistant isolates, the relevant ß-lactamase genes (bla(TEM), bla(SHV), bla(CTX-M-1/2/9) group, bla(CMY-2) and bla(KPC)) were detected by PCR analysis. Of the 447 isolates tested, 120 (26.8 %) were confirmed as producing ESBL. Among these, 70 and 40 human isolates carried a member of the bla(CTX-M-1 )group (13 bla(CTX-M-3), 21 bla(CTX-M-15), four bla(CTX-M-22), eight bla(CTX-M-28), four bla(CTX-M-36), 15 bla(CTX-M-55) and five bla(CTX-M-69)) or bla(SHV) (14 bla(SHV-2), seven bla(SHV-5), ten bla(SHV-12), five bla(SHV-57) and four bla(SHV-97)),respectively, whilst six and four swine isolates carried a member of the bla(CTX-M-1 )group (one bla(CTX-M-15) and five bla(CTX-M-22)) or bla(SHV) (three bla(SHV-2) and one bla(SHV-12)), respectively. Furthermore, 59 human and swine isolates and seven human isolates carried bla(CMY-2) and bla(KPC), respectively. These findings indicate that the bla(CTX-M-1) group, including the novel variant bla(CTX-M-69), and bla(SHV) are the predominant ESBL genes in both humans and swine in western China, and bla(CMY-2) is also common in both groups. The carriage rates of broad-spectrum ß-lactamases among commensal E. coli was much lower in swine than in humans, suggesting that ß-lactamase genes have not established themselves in animal ecosystems in western China.