This study was conducted to analyze the effects of sodium nitrite,nisin,potassium sorbate,and sodium lactate against Staphylococcus aureus(S.aureus)growth and staphylococcal enterotoxins(SEs)production in cooked pork ...This study was conducted to analyze the effects of sodium nitrite,nisin,potassium sorbate,and sodium lactate against Staphylococcus aureus(S.aureus)growth and staphylococcal enterotoxins(SEs)production in cooked pork sausage by inoculating sausage samples containing preservative with an S.aureus strain producing staphylococcal enterotoxin A(SEA)and then storing them at 37℃ for 36 h.Samples were analyzed every 3 h to count the S.aureus colonies and to detect SEA.The modified Gompertz model was used to describe S.aureus growth in the samples under various conditions,and the preservatives with a significant antimicrobial effect were selected.In addition,the antimicrobial effects of the selected preservatives under various concentrations were tested.Results showed that sodium nitrite,nisin,and potassium sorbate had a weak effect against S.aureus growth and had no effect against SEA production,whereas sodium lactate could significantly inhibit S.aureus growth and SEA production.Moreover,the antimicrobial effect of sodium lactate was concentration-dependent,wherein sodium lactate concentration<12 g/kg showed no inhibitory effect,but when the concentration was increased to 24 g/kg,sodium lactate could effectively inhibit S.aureus growth and SEA production,and at 48 g/kg,sodium lactate had a significant inhibitory effect.展开更多
The anti-tumor effect and mechanism of the staphylococcal enterotoxin A (SEA) were studied. The mouse gastric tumor model was produced by subcutaneously inoculating gastric tumor ceils (MGC80-3). The experimental grou...The anti-tumor effect and mechanism of the staphylococcal enterotoxin A (SEA) were studied. The mouse gastric tumor model was produced by subcutaneously inoculating gastric tumor ceils (MGC80-3). The experimental group was treated with SEA, and the control group was treated with normal saline. The percentage of tumor generation and tumor mass was measured. The results showed that the percentage of the tumor generation in the SEA-treated mice was lower than in the control group, but there was no significant difference (P>0. 05). However, the tumor mass in the experimental group was significantly lighter than in the control group, with the difference being very significant (P<0. 001). There were more CD4+ T cells and CD8+ T cells in the tumor of the mice treated with SEA than those of the control group. SEA has an obvious anti-tumor effect on mice gastric tumor. The mechanism might be that SEA induces the effect of superantigen-dependent cell mediated cytotoxicity to the tumor cells.展开更多
Objective To observe the role of superantigen staphylococcal enterotoxin B(SEB) andD - galactosamine (D - GalN) on Balb/c mouse hepatocytes and its mechanism. Methods After Balb/c mice wereinjected intraperitoneally w...Objective To observe the role of superantigen staphylococcal enterotoxin B(SEB) andD - galactosamine (D - GalN) on Balb/c mouse hepatocytes and its mechanism. Methods After Balb/c mice wereinjected intraperitoneally with SEB, D- GalN or both, blood samples were collected and livers were removed at 2,6, 12, 24h. Patterns of hepatocellular death were studied morphologically and biochemically, circulating cytokines(TNF, IFN-γ) were determined, and mice mortality within 24h was assessed. Results SEB could induce thetypical apoptotic changes of hepatocytes morphologically and biochemically. The mechanism is probably associatedwith the production and release of Cytokines (such as TNF, IFN- γ, etc).D - GalN could induce hepatocytesapoptosis and degeneration at the same time. Besides this, we confirmed hepatocytes of the mice which wereadministered SEB and D - GalN developing apoptosis at 2, 6h, but after 12h hepatocytes were characterized bysevere injury, the mice mortality within 24h is 50%. Conclusion SEB or D - GalN alone could induce the typicalapoptotic changes of hepatocytes. SEB+D-GalN developed hepatocytes apoptosis in the early stage and necrosisin the later. It suggests that there is some relationship between hepatic cell apoptosis and necrosis, and massivehepatocyte apoptosis is the probably initiating step of acute hepatic necrosis in mice.展开更多
Staphylococcal Enterotoxin B (SEB) is considered a potential biological weapon. It is toxic by both inhalation and ingestion. Effects of ingestion include fever, vomiting and diarrhoea, while inhalation may additional...Staphylococcal Enterotoxin B (SEB) is considered a potential biological weapon. It is toxic by both inhalation and ingestion. Effects of ingestion include fever, vomiting and diarrhoea, while inhalation may additionally result in chest pain, dyspnoea, pulmonary oedema and respiratory failure. Severe exposure may be fatal and treatment relies on symptomatic support. At a cellular level, SEB up-regulates T-cell proliferation leading to a pathological inflammatory response. Deguelin, a rotenoid isolated from the African plant Mundulea sericea (Leguminosae), has been shown to reduce cellular proliferation by inhibiting the phosphoinositide 3-kinase/Akt (PI3K/Akt) signalling pathway. Using isolated murine splenocytes, we have demonstrated that treatment with deguelin reduces SEB inducing T cell proliferation by 60%. Deguelin treatment also decreased IL-2 and CCL2 secretion by splenocytes exposed to SEB. We demonstrate that targeting cellular proliferation can significantly reduce inflammation after SEB exposure and suggest that anti-proliferatives may have a role as potential generic medical counter measures if superantigens are used as biological weapons.展开更多
Staphylococcal enterotoxin A(SEA)derived from Staphylococcus aureus,as a superantigen,shows potential for cancer immunotherapy,but systemic immunotoxicity restricts its clinical application.Targeted delivery of SEA to...Staphylococcal enterotoxin A(SEA)derived from Staphylococcus aureus,as a superantigen,shows potential for cancer immunotherapy,but systemic immunotoxicity restricts its clinical application.Targeted delivery of SEA to tumor site provides a promising option for reducing the systemic toxicity.Here,we constructed an iRGD peptide(H-[Cys-Arg-Gly-Asp-Lys-Gly-Pro-Asp-Cys]-NH_(2))modified nanoparticle(iDPP)to deliver plasmids encoding SEA for melanoma treatment.The iDPP/SEA nanocomplexes efficiently mediated SEA expression in B16-F10 cells in vivo and in vitro and induced the activation of lymphocytes and maturation of murine bone marrow-derived dendritic cells(BMDCs)in vitro.In the subcutaneous B16-F10 melanoma model,the iDPP/SEA nanocomplexes could effectively enhance immune response and T lymphocytes infiltration in tumor site after intravenous administration,thereby considerably decreased melanoma growth.Meanwhile,no obvious adverse effect was observed after intravenous administration of the iDPP/SEA nanocomplexes in vivo.Our findings demonstrated that gene therapy of SEA is a potential candidate for melanoma treatment.展开更多
Predictive microbiology was utilized to model Staphylococcus aureus （S. aureus） growth and staphylococcal enterotoxin A （SEA） production in milk in this study. The modifed logistic model, modifed Gompertz model an...Predictive microbiology was utilized to model Staphylococcus aureus （S. aureus） growth and staphylococcal enterotoxin A （SEA） production in milk in this study. The modifed logistic model, modifed Gompertz model and Baranyi model were applied to model growth data of S. aureus between 15℃ and 37℃. Model comparisons indicated that Baranyi model described the growth data more accurately than two others with a mean square error of 0.0129. Growth rates generated from Baranyi model matched the observed ones with a bias factor of 0.999 and an accuracy factor of 1.01, and ft a square root model with respect to temperature; other two modifed models both overestimated the observed ones. SEA amount began to be detected when the cell number reached106.4 cfu ？ mL-1, and showed the linear correlation with time. Besides, the rate of SEA production ftted an exponential relationship as a function of temperature. Predictions based on the study could be applied to indicate possible growth of S. aureus and prevent the occurrence of staphylococcal food poisoning.展开更多
基金Development of Application Technology Project(No:2015-114)issued by Science and Technology Committee of Shanghai Municipal GovernmentNational Key Scientific Instruments Project(No:2013YQ150557)issued by Ministry of Science and Technology of the P.R.China.
文摘This study was conducted to analyze the effects of sodium nitrite,nisin,potassium sorbate,and sodium lactate against Staphylococcus aureus(S.aureus)growth and staphylococcal enterotoxins(SEs)production in cooked pork sausage by inoculating sausage samples containing preservative with an S.aureus strain producing staphylococcal enterotoxin A(SEA)and then storing them at 37℃ for 36 h.Samples were analyzed every 3 h to count the S.aureus colonies and to detect SEA.The modified Gompertz model was used to describe S.aureus growth in the samples under various conditions,and the preservatives with a significant antimicrobial effect were selected.In addition,the antimicrobial effects of the selected preservatives under various concentrations were tested.Results showed that sodium nitrite,nisin,and potassium sorbate had a weak effect against S.aureus growth and had no effect against SEA production,whereas sodium lactate could significantly inhibit S.aureus growth and SEA production.Moreover,the antimicrobial effect of sodium lactate was concentration-dependent,wherein sodium lactate concentration<12 g/kg showed no inhibitory effect,but when the concentration was increased to 24 g/kg,sodium lactate could effectively inhibit S.aureus growth and SEA production,and at 48 g/kg,sodium lactate had a significant inhibitory effect.
文摘The anti-tumor effect and mechanism of the staphylococcal enterotoxin A (SEA) were studied. The mouse gastric tumor model was produced by subcutaneously inoculating gastric tumor ceils (MGC80-3). The experimental group was treated with SEA, and the control group was treated with normal saline. The percentage of tumor generation and tumor mass was measured. The results showed that the percentage of the tumor generation in the SEA-treated mice was lower than in the control group, but there was no significant difference (P>0. 05). However, the tumor mass in the experimental group was significantly lighter than in the control group, with the difference being very significant (P<0. 001). There were more CD4+ T cells and CD8+ T cells in the tumor of the mice treated with SEA than those of the control group. SEA has an obvious anti-tumor effect on mice gastric tumor. The mechanism might be that SEA induces the effect of superantigen-dependent cell mediated cytotoxicity to the tumor cells.
文摘Objective To observe the role of superantigen staphylococcal enterotoxin B(SEB) andD - galactosamine (D - GalN) on Balb/c mouse hepatocytes and its mechanism. Methods After Balb/c mice wereinjected intraperitoneally with SEB, D- GalN or both, blood samples were collected and livers were removed at 2,6, 12, 24h. Patterns of hepatocellular death were studied morphologically and biochemically, circulating cytokines(TNF, IFN-γ) were determined, and mice mortality within 24h was assessed. Results SEB could induce thetypical apoptotic changes of hepatocytes morphologically and biochemically. The mechanism is probably associatedwith the production and release of Cytokines (such as TNF, IFN- γ, etc).D - GalN could induce hepatocytesapoptosis and degeneration at the same time. Besides this, we confirmed hepatocytes of the mice which wereadministered SEB and D - GalN developing apoptosis at 2, 6h, but after 12h hepatocytes were characterized bysevere injury, the mice mortality within 24h is 50%. Conclusion SEB or D - GalN alone could induce the typicalapoptotic changes of hepatocytes. SEB+D-GalN developed hepatocytes apoptosis in the early stage and necrosisin the later. It suggests that there is some relationship between hepatic cell apoptosis and necrosis, and massivehepatocyte apoptosis is the probably initiating step of acute hepatic necrosis in mice.
文摘Staphylococcal Enterotoxin B (SEB) is considered a potential biological weapon. It is toxic by both inhalation and ingestion. Effects of ingestion include fever, vomiting and diarrhoea, while inhalation may additionally result in chest pain, dyspnoea, pulmonary oedema and respiratory failure. Severe exposure may be fatal and treatment relies on symptomatic support. At a cellular level, SEB up-regulates T-cell proliferation leading to a pathological inflammatory response. Deguelin, a rotenoid isolated from the African plant Mundulea sericea (Leguminosae), has been shown to reduce cellular proliferation by inhibiting the phosphoinositide 3-kinase/Akt (PI3K/Akt) signalling pathway. Using isolated murine splenocytes, we have demonstrated that treatment with deguelin reduces SEB inducing T cell proliferation by 60%. Deguelin treatment also decreased IL-2 and CCL2 secretion by splenocytes exposed to SEB. We demonstrate that targeting cellular proliferation can significantly reduce inflammation after SEB exposure and suggest that anti-proliferatives may have a role as potential generic medical counter measures if superantigens are used as biological weapons.
基金supported by the National Natural Science Foundation(No.82073363)the Sichuan Science and Technology Program(Nos.2020YFQ0059,2022YFQ0004)the Natural Science Foundation of Sichuan Province(No.2022NSFSC1304).
文摘Staphylococcal enterotoxin A(SEA)derived from Staphylococcus aureus,as a superantigen,shows potential for cancer immunotherapy,but systemic immunotoxicity restricts its clinical application.Targeted delivery of SEA to tumor site provides a promising option for reducing the systemic toxicity.Here,we constructed an iRGD peptide(H-[Cys-Arg-Gly-Asp-Lys-Gly-Pro-Asp-Cys]-NH_(2))modified nanoparticle(iDPP)to deliver plasmids encoding SEA for melanoma treatment.The iDPP/SEA nanocomplexes efficiently mediated SEA expression in B16-F10 cells in vivo and in vitro and induced the activation of lymphocytes and maturation of murine bone marrow-derived dendritic cells(BMDCs)in vitro.In the subcutaneous B16-F10 melanoma model,the iDPP/SEA nanocomplexes could effectively enhance immune response and T lymphocytes infiltration in tumor site after intravenous administration,thereby considerably decreased melanoma growth.Meanwhile,no obvious adverse effect was observed after intravenous administration of the iDPP/SEA nanocomplexes in vivo.Our findings demonstrated that gene therapy of SEA is a potential candidate for melanoma treatment.
基金Supported by"Academic Backbone"Project of Northeast Agricultural University(15XG26)the National High-level Talents Special Support Program of China
文摘Predictive microbiology was utilized to model Staphylococcus aureus （S. aureus） growth and staphylococcal enterotoxin A （SEA） production in milk in this study. The modifed logistic model, modifed Gompertz model and Baranyi model were applied to model growth data of S. aureus between 15℃ and 37℃. Model comparisons indicated that Baranyi model described the growth data more accurately than two others with a mean square error of 0.0129. Growth rates generated from Baranyi model matched the observed ones with a bias factor of 0.999 and an accuracy factor of 1.01, and ft a square root model with respect to temperature; other two modifed models both overestimated the observed ones. SEA amount began to be detected when the cell number reached106.4 cfu ？ mL-1, and showed the linear correlation with time. Besides, the rate of SEA production ftted an exponential relationship as a function of temperature. Predictions based on the study could be applied to indicate possible growth of S. aureus and prevent the occurrence of staphylococcal food poisoning.
