Staphylococcal enterotoxin B as DNA vaccine against breast cancer in a murine model / Enterotoxina B estafilocócica como vacuna de ADN contra el cáncer de mama en un modelo murino

Recently, many efforts have been made to treat cancer using recombinant bacterial toxins and this strategy has been used in clinical trials of various cancers. Therapeutic DNA cancer vaccines are now considered as a promising strategy to activate the immune system against cancer. Cancer vaccines could induce specific and long-lasting immune responses against tumors. This study aimed to evaluate the antitumor potency of the SEB DNA vaccine as a new antitumor candidate against breast tumors in vivo. To determine the effect of the SEB construct on inhibiting tumor cell growth in vivo, the synthetic SEB gene, subsequent codon optimization, and embedding the cleavage sites were sub-cloned to an expression vector. Then, SEB construct, SEB, and PBS were injected into the mice. After being vaccinated, 4T1 cancer cells were injected subcutaneously into the right flank of mice. Then, the cytokine levels of IL-4 and IFN-γ were estimated by the ELISA method to evaluate the antitumor activity. The spleen lymphocyte proliferation, tumor size, and survival time were assessed. The concentration of IFN-γ in the SEB-Vac group showed a significant increase compared to other groups. The production of IL-4 in the group that received the DNA vaccine did not change significantly compared to the control group. The lymphocyte proliferation increased significantly in the mice group that received SEB construct than PBS control group (p < 0.001). While there was a meaningful decrease in tumor size (p < 0.001), a significant increase in tumor tissue necrosis (p < 0.01) and also in survival time of the animal model receiving the recombinant construct was observed.(AU)

Induction of nasal polyps using house dust mite and Staphylococcalenterotoxin B in C57BL/6 mice

BACKGROUND: The murine polyp model was developed previously using ovalbumin and Staphylococcus aureusenterotoxin B (SEB). Here, we established a model mimicking key aspects of chronic eosinophilic rhinosinusitis with nasal polyps using the house dust mite (HDM), a clinically relevant aeroallergen, co-administered with SEB. We assessed the inflammatory response and formation of nasal polypoid lesions in an experimental murine model using intranasal delivery of HDM and ovalbumin. METHODS: After induction of HDM-induced allergic rhinosinusitis in C57BL/6 mice, SEB (10 ng) was instilled into the nasal cavity of mice for eight weeks. Phosphate-buffered saline-challenged mice served as control. Histopathological changes were evaluated using haematoxylin and eosin for overall inflammation, Sirius red for eosinophils, and periodic acid-Schiff stain for goblet cells. The distribution of mast cells in mouse nasal tissue was determined by immunohistochemistry. Serum total IgE was measured using enzyme-linked immunosorbent assay. RESULTS: Compared to mice treated with HDM only, the HDM + SEB-treated mice demonstrated nasal polypoid lesion formation and a significant increase in the number of secretory cells and eosinophilic infiltration. Moreover, mice challenged intranasally with HDM showed highly abundant mast cells in the nasal mucosa. In contrast, OVA + SEB-challenged mice showed a significantly lower degree of mast cell infiltration. CONCLUSION: We established an in vivo model of chronic allergic rhinosinusitis with nasal polypoid lesions using HDM aeroallergen. This study demonstrated that the HDM + SEB-induced murine polyp model could be utilised as a suitable model for nasal polyps, especially with both eosinophil and mast cell infiltration

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Enterocyte chloride and water secretion into the small intestine after enterotoxin challenge: Unifying hypothesis or intellectual dead end?

Many forms of diarrhoeal disease, particularly so called "secretory" diarrhoealdisease are thought to arise by the active secretion of chloride ion from the enterocytes,creating an osmotic gradient for fluid movement into the small intestinallumen. This model implies that normally occurring intestinal secretion is catastrophicallyenhanced by bacterial enterotoxins. This review advocates that neither normalnor abnormal intestinal secretion from the enterocytes occurs and that no competentproof for chloride secretion exists. Prior to 1970, the physiological evidence failed tosupport the concept of the formation of intestinal juice as a normal intestinal event.The concept was later revived to explain the high rate of fluid entry into the lumenafter exposure to cholera toxin. Much evidence has been advanced for the chloridesecretion hypothesis, the dominant secretory paradigm after 1974, but is the evidencesufficiently compelling for it to be regarded as proving the chloride secretory model?. The evidence falls into four categories and a fifth conjectural argument that proposes that an abnormal chloride ion channel in cystic fibrotic sufferers confers a natural selective advantage by preventing diarrhoeal disease. Secretion is putatively demonstrated by 1) showing that mass transfer of fluid is into the lumen (secretion) and not merely a failure to transport out of the lumen (failed absorption). Support is offered by 2) chloride ion flux measurements in vitro in Ussing chambers and by 3) shortcircuit current measurements that are consistent with and purport to show chloride ion movement into the lumen. In addition, 4) pharmacological agents are identified that affect short-circuit current and these are assumed to be anti-secretory, consistent with the biochemical mechanism for secretion, confirmed wherever possible by mouse knock-out models. Finally, the proxy methods used to study water movement such as elevated short-circuit current measurements show these to be absent in cystic fibrotic patients. The enterocyte secretion hypothesis is challenged here on the basis of an examination of the methods used to show secretion, particularly after exposing the small intestine to heat stable enterotoxin (STa) from E.coli. STa is thought to be secretory because fluid entry into the lumen is claimed, enhanced isotopic flux of chloride ion towards the lumen occurs, an increase in short-circuit current is found, preventable by various drugs that are deemed likely to be anti-secretory and also because the short-circuit current changes after STa are not seen in cystic fibrotic patients. Using volume recovery in vivo, STa is found not to be secretory but only anti-absorptive. Hence, other techniques used to show secretion are not fit for that purpose. If STa is identified as secretory and yet no secretion occurs, how reliable is the evidence for other toxins being secretory when these methods are used? This review concludes that chloride ion secretion is unproven. A review of the literature indicates that secretion occurs not because epithelial cells actively pump water but by interdiction of fluid absorption, increased conductivity through tight junctions and an increased hydrostatic driving force through elevated capillary pressure.The exclusive focus on chloride secretion may explain the failure to develop antisecretory drugs over the last three decades (AU)

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Lack of evidence in vivo for nitrergic inhibitionby Escherichia coli (STa) enterotoxin of fluidabsorption from rat proximal jejunum

Fluid absorption from the proximal jejunum of the anaesthetised rat was measuredin vivo by fluid recovery. As expected, heat stable (STa) enterotoxin fromE.coli reduced fluid absorption. Neither intraperitoneal L-NAME, thought to inhibita putative neurally mediated action of STa, nor similar doses of D-NAME,ameliorated the inhibitory effect on jejunal fluid absorption of STa. Luminally perfused10 mM sodium nitroprusside (SNP) had no effect on fluid absorption whenexpressed per gram dry weight per hour but reduced fluid absorption whenexpressed per cm length per hour. Similarly, 80 but not 40 mg/Kg of L-NAMEreduced fluid absorption when expressed per cm length per hour, while the samedose of D-NAME did not. L-NAME and SNP significantly increased the wet weightto dry weight and the length to dry weight ratio of perfused loops. We conjecturethat smooth muscle relaxation caused by these compounds increases interstitial fluidvolumes that can be misconstrued as changes in absorption when this is expressed percm length or per tissue wet weight. When fluid absorption is expressed per gram dryweight of tissue, there is no evidence for a role of nitric oxide in normal or STa inhibitedfluid absorption (AU)

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Lack of evidence in vivo for nitrergic inhibition by Escherichia coli (STa) enterotoxin of fluid absorption from rat proximal jejunum

Fluid absorption from the proximal jejunum of the anaesthetised rat was measuredin vivo by fluid recovery. As expected, heat stable (STa) enterotoxin fromE.coli reduced fluid absorption. Neither intraperitoneal L-NAME, thought to inhibita putative neurally mediated action of STa, nor similar doses of D-NAME,ameliorated the inhibitory effect on jejunal fluid absorption of STa. Luminally perfused10 mM sodium nitroprusside (SNP) had no effect on fluid absorption whenexpressed per gram dry weight per hour but reduced fluid absorption whenexpressed per cm length per hour. Similarly, 80 but not 40 mg/Kg of L-NAMEreduced fluid absorption when expressed per cm length per hour, while the samedose of D-NAME did not. L-NAME and SNP significantly increased the wet weightto dry weight and the length to dry weight ratio of perfused loops. We conjecturethat smooth muscle relaxation caused by these compounds increases interstitial fluidvolumes that can be misconstrued as changes in absorption when this is expressed percm length or per tissue wet weight. When fluid absorption is expressed per gram dryweight of tissue, there is no evidence for a role of nitric oxide in normal or STa inhibitedfluid absorption (AU)

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Enterotoxinas y enzimas estafilococcicas en presencia de aceites esenciales / Staphylococcal enterotoxins and enzymes in presence of essential oils

Nuestro objetivo fue investigar el efecto de concentraciones subinhibitorias de clavo, canela, y tomillo en el crecimiento de S aureus y en la producción de coagulasa, termonucleasa y enterotoxina. Con ese fi n se agregaron diferentes concentraciones de los aceites esenciales a Caldo Cerebro Corazón. La producción de enterotoxina en presencia y en ausencia de los aceites esenciales se determinó por la técnica de enzimoinmunoensayo (ELISA). Nuestros resultados indican que bajas concentraciones que no afectan el crecimiento, reducen la producción de la producción de las enzimas ensayadas y de enterotoxina El aceite esencial de tomillo es el que presenta mayor actividad pues al 0,04% produce la pérdida de la actividad de ambas enzimas y de la enterotoxicidad Esto es importante cuando consideramos su potencial aplicación en alimentos y en la industria farmacéutica

Our aim was to investigate the effect of subinhibitory concentrations of clove, cinnamon, and thyme essential oils on the growth of Staphylococcus aureus and its production of coagulase, thermonuclease and enterotoxin. Different concentrations of the essential oils were added to Brain Heart Infusion broth. The production of enterotoxin in the presence or absence of essential oils was estimated using the ELISA technique. Our results indicate that a lower concentration did not affect the growth S. aureus but reduced the production of metabolites. Thyme oil presents the most signifi cant effect, inhibiting the activity of both enzymes and the production of enterotoxin with 0,04%. There is a renewed interest in the potential application of these essential oils in the food and pharmaceutical industries to control staphylococcal poisoning

Brote de toxiinfección alimentaria por Clostridiumperfringens en un comedor escolar / Foodborne outbreak by Clostridium perfringens in a school dining room

FUNDAMENTO Y OBJETIVO: Investigar las características epidemiológicas y la etiología de un brote de origen alimentario en un comedor escolar. SUJETOS Y MÉTODO: Estudio de cohortes retrospectivo. Se recogió información sobre la utilización del servicio de comedor del colegio y la presencia de síntomas de gastroenteritis. Se realizaron coprocultivos de siete pacientes y se investigó la presencia de enterotoxina de Clostridium perfringens en heces mediante aglutinación pasiva reversa por látex. Se calcularon los riesgos relativos (RR) y sus intervalos de confianza (IC) del 95 por ciento. RESULTADOS: La tasa de ataque fue del 17,5 por ciento (48/275) y la probabilidad de enfermar resultó superior en los alumnos del segundo turno de comida con respecto a los del primero (RR = 13,8; IC del 95 por ciento, 4,4-43,1). En 6 muestras de heces de enfermos se detectó la presencia de enterotoxina de C. perfringens. En las muestras testigo de los alimentos del menú que se mantuvieron congeladas tras su elaboración no se observó un recuento elevado de C. perfringens. CONCLUSIONES: La determinación de la enterotoxina de C. perfringens en heces permitió confirmar la etiología del brote (AU)

Escherichia coli isolated from seafood: toxicity and plasmid profiles

Thirty-two Escherichia coli strains were isolated from red snapper (Lutjanus purpureus) and from seabob shrimp (Xiphopenaeus kroyeri). The strains were numbered S1-S16, and F1-F16, which corresponds to the isolation origin from shrimp (S) and fish (F). The isolates were biologically and antigenically characterized by agglutination tests with enteropathogenic E. coli (EPEC)-, enteroinvasive E. coli (EIEC)- and enterohemorrhagic E. coli (EHEC) O157-specific antisera. The ETEC enterotoxins were characterized by GMI-ELISA for enterotoxin LT-1 (thermolabile) and by inoculation of supernatants prepared from newly born mice for enterotoxin Sta. A total of 14 strains produced exotoxins, of which seven were thermolabile (LT) and seven were thermostable (ST). Antimicrobial susceptibility profiles were determined by disc diffusion in agar using ampicillin, cephalothin, cefoxitin, ceftriaxone, imipenem, nalidixic acid, ciprofloxacin, chloramphenicol, gentamicin, nitrofurantoin, sulfamethoxazole-trimethoprim, and tetracycline. Four isolates showed lower susceptibility to some antibiotics, two strains were resistant to ampicillin, tetracycline, and sulfamethoxazole-trimethoprim, and two were resistant to tetracycline and nitrofurantoin. Plasmids were extracted in the four resistant isolates; two of them contained plasmids whose molecular weight varied from low to high. The characterization of LT- and ST-toxin-producing E. coli strains displaying multiresistance and containing plasmids suggests the need for tightening current control measures for the use of antimicrobials (AU)

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Adecuación de pautas vacunales en viajes internacionales. Vacunas en desarrollo / Adecuation of vaccination to the international traveller. Vaccines under development

Los importantes movimientos poblacionales y los viajes a países exóticos tan frecuentes en los tiempos modernos hacen que cada vez más a menudo el médico sea consultado sobre vacunaciones o medidas preventivas que un viajero debería recibir antes de emprender su viaje. Actualmente la Organización Mundial de la Salud (OMS) sólo exige la vacunación de la Fiebre Amarilla cuando se viaje a zonas endémicas así como la vacuna antimeningocócica para entrar en Arabia Saudí, el resto de las vacunas disponibles serán recomendadas según el tipo de viaje y la situación del viajero (AU)