ABSTRACT
Objective To investigate the contamination status of Salmonella, Vibrio parahaemo-lyticus and Staphylococcus aureus and bacterial resistance in retail meat products in Taiyuan, Shanxi Prov-ince. Methods In the epidemic season of diarrhea in 2017, poultry and meat product specimens were ran-domly collected from the farmer's markets and supermarkets of 10 districts and counties of Taiyuan. Salmo-nella, Vibrio parahaemolyticus and Staphylococcus aureus were isolated form these specimens. Serotypes of Salmonella strains were analyzed. ELSIA was used to detect Staphylococcus aureus enterotoxin (A-E). Vibrio parahaemolyticus isolates were tested for the virulence genes encoding direct hemolysin (tdh) and indirect hemolysin (trh). Antibiotic resistance of the three food-borne pathogens were analyzed using microdilution methods. Results A total of 38 food-borne pathogens were isolated from 123 poultry and livestock meat product specimens with a positive rate of 30. 9％ , of which mainly were Salmonella (26 strains, 21. 1％ ), followed by Vibrio parahaemolyticus (8 strains, 6. 5％ ) and Staphylococcus aureus (4 strains, 3. 3％ ). The 26 strains of Salmonella belonged to 10 serotypes. The Salmonella strains isolated from pork specimens had diverse serotypes. Salmonella serovar Derby, Salmonella serovar Gold-coast and Salmonella serovar Liver-pool were isolated from raw and cooked pork food for the first time in Taiyuan. All Salmonella strains isolated form chicken products were Salmonella enteritis. The enterotoxin types of the four Staphylococcus aureus strains were three E-type and one complex type (A/ E). All Vibrio parahaemolyticus isolates were negative for tdh or trh gene. Ampicillin, chloramphenicol, streptomycin, sulphonamides and tetracyclines (ACSSuT) resistance was prevalent in multi-drug resistant (MDR) Salmonella strains, but there was high sensitivity to fluoroquinolones and cephalosporins. MDR Staphylococcus aureus accounted for 75％ . No third-generation cephalosporin- or fluoroquinolone-resistant or MDR Vibrio parahaemolyticus strains were isolated. Conclu-sions There were food-borne multi-pathogenic bacteria contamination in retail raw and cooked meat prod-ucts in Taiyuan. Salmonella strains had diverse serotypes and high MDR rate. It was suggested that the regu-latory authorities should strengthen the management of antibiotic use in aquaculture and specialized laborato-ry-based monitoring of meat supply chain.
ABSTRACT
Aim To investigate the effect of adenosine on the autophagy and proliferation of hepatocellular carcinoma cells, and improve the curative effect of a-denosine on hepatocellular carcinoma. Methods HepG2 cells were incubated with adenosine, CCK-8 method was used to study the changes of cell prolifera-tion,Western blot was used to study the expression of LC3-Ⅱ and LC3-Ⅰ, and MDC staining was used to observe the number of autophagosomes. Results HepG2 cells were incubated with adenosine(1.0~4.0 mmol·L-1) for 48 h,the proliferation of HepG2 cells were detected at the different time points (12,24,48 h),and the result showed the proliferation was signifi-cantly inhibited by adenosine (P < 0.01). HepG2 cells were incubated with adenosine (0.2,0.5,1.0, 2.0,4.0 mmol·L-1) for 24 h,the ratio of LC3-Ⅱ/LC3-Ⅰ decreased significantly in low concentration of adenosine group (0.2, 0.5 mmol·L-1, P <0.05;1.0 mmol·L-1,P<0.01),and the ratio of LC3-Ⅱ/LC3-Ⅰ increased significantly in higher concentration of adenosine group (4.0 mmol·L-1, P <0.05). HepG2 cells were incubated with adenosine(1.0 mmol·L-1) for 24 h, the ratio of LC3-Ⅱ/LC3-Ⅰ de-creased significantly at 6,12 and 24 h detecting point, the number of autophagosomes were reduced, the low-est ratio of LC3-Ⅱ/LC3-Ⅰ and autophagosomes were observed at 12 h detecting point(P<0.01). Conclu-sions Adenosine inhibits the proliferation of hepato-cellular carcinoma cells,the low concentration of aden-osine inhibits the autophagy,while the high concentra-tion of adenosine increases the autophagy, which is of great significance to reduce multi-drug resistance and improve the therapeutic effect of anti-hepatoma drugs.