AiiA quorum-sensing quenching controls proteolytic activity and biofilm formation by Enterobacter cloacae.

The aim of this work was to evaluate a quorum-quenching approach to identify functions regulated by quorum sensing in Enterobacter cloacae. We employed an aiiA transconjugant strain of E. cloacae that synthesizes a lactonase enzyme that hydrolyzes N-acyl homoserine lactone signaling molecules to compare bacterial phenotypes in the presence and absence of quorum signals. The aiiA-expressing strain displayed increased proteolytic activity and intensity of a milk-clotting reaction when compared to the wild-type strain. Although both strains growing on polystyrene plates in rich media and a minimal medium of salts formed biofilms, the wild-type strain exhibited a higher number of adhered cells. On the surface of stainless steel coupons that were submerged in culture media, the number of adhered cells of the wild type contained up to one log more cells compared with the aiiA transconjugant. However, after 48 h of incubation, there was no significant difference between the strains. The results demonstrated that the quorum-sensing system negatively regulates proteolytic activity and is likely involved in the early steps of biofilm formation by E. cloacae 067.

Biofilm formation and acyl homoserine lactone production in Hafnia alvei isolated from raw milk.

The objective of this study was to detect the presence of acyl homoserine lactones (AHLs), signal molecules of the quorum sensing system in biofilm formed by Hafnia alvei strains. It also evaluated the effect of synthetic quorum sensing inhibitors in biofilm formation. AHLs were assayed using well diffusion techniques, thin layer chromatography (TLC) and detection directly in biofilm with biomonitors. The extracts obtained from planktonic and sessile cell of H. alvei induced at least two of three monitor strains evaluated. The presence of AHLs with up to six carbon atoms was confirmed by TLC. Biofilm formation by H. alvei was inhibited by furanone, as demonstrated by 96-well assay of crystal violet in microtitre plates and by scanning electron microscopy. The H. alvei 071 hall mutant was deficient in biofilm formation. All these results showed that the quorum sensing system is probably involved in the regulation of biofilm formation by H. alvei.

Effects of TiO2 NPs coating-titanium for fibroblast adhesion / Efectos del recubrimiento de NPs de TiO2 sobre placas de titanio para la adhesión de fibroblastos

The objective of this study was to determine the effects of coating nanoparticles of titanium dioxide (TiO2 NPs) and irradiation -UV on plates of titanium (Ti) for the adhesion and proliferation of human gingival fibroblasts (HGF). A total of 15 Ti plates were divided into three groups (n = 5); (i) control Ti, (ii) experimental: Ti+TiO2 NPs, (iii) experimental: Ti+TiO2 NPs+UV. The plates were analyzed with atomic force microscopy (AFM) and the roughness (Ra and Rmax) was determined. UV irradiation was performed for 20 min. HGF were subcultured in DMEM+10 % fetal bovine serum (FBS) at 37 °C with 5 % CO2. 2x106 cells/mL were inoculated on the plates and incubated for 1 h and washed with phosphate buffer saline (PBS). In the case of cell proliferation, cells were incubated for further 24 h more. Cell viability was determined with the MTT method, the formazan was dissolved with dimethylsulfoxide (DMSO) and analyzed at 540 nm. Experiments were performed of three independent experiments and data were analyzed by Kruskall-Wallis and multiple comparison of Mann-Whitney test. The surface topography of samples corresponded as follow: Ti (Ra= 0,492 µm y Rms= 0.640 µm), Ti+NPs TiO2, (Ra= 0.55 µm y Rms= 0.714 µm), respectively. The coating with TiO2 NPs significantly (p <0.05) increased the adhesion and proliferation of HGF compared with the group. The modification of Ti plates by coated with TiO2 NPs significantly increased adhesion and proliferation of HGF with the formation of a hydrophilic surface which favors the humectancy. This treatment may be reported here convenient to accelerate osseointegration of dental implants based titanium.

El objetivo fue determinar los efectos del recubrimiento con nanopartículas de dióxido de titanio (TiO2 NPs) e irradiación UV sobre placas de titanio (Ti) para la adhesión y proliferación de fibroblastos gingivales humanos (FGH). Un total de 15 placas de Ti se dividieron en tres grupos (n= 5); (i) control Ti, (ii) experimental Ti+NPs TiO2, (iii) experimental: Ti+NPs TiO2+UV. Las placas fueron analizadas en microscopía de fuerza atómica (MFA) y se determinó la rugosidad (Ra y Rmax). La irradiación con UV se realizó durante 20 min. FGH fueron subcultivados en DMEM+10 % de suero fetal bovino a 37 °C con 5 % de CO2. 2x106 células/mL fueron inoculadas sobre las placas e incubadas durante 1 h, se lavaron con solución salina de buffer fosfato. En el caso de la proliferación celular, las células se incubaron por 24 h más. La viabilidad celular se determinó con el método de MTT, el formazan fue disuelto con dimetilsulfoxido y se analizó a 540 nm. Los experimentos se realizaron a partir de tres experimentos independientes y los datos se analizaron por Kruskall-Wallis y por comparación múltiple de Mann-Whitney. La topografía de la superficie de las muestras correspondio de la siguiente manera: Ti (Ra= 0,492 µm y Rms= 0,640 µm), Ti+NPs TiO2, (Ra= 0,55 µm y Rms= 0,714 µm), respectivamente. El recubrimiento con NPs TiO2 aumentó significativamente la adhesión y proliferación de HGF en comparación con el grupo de Ti control (p <0,05). La modificación de la superficie de las placas de Ti recubiertas con NPs TiO2 aumentó significativamente la adhesión y proliferación de HGF con la formación de una superficie hidrófila que favorece la humectancia. Este tratamiento aquí informado tal vez sea un método conveniente para acelerar el proceso de la osteointegración de los implantes dentales a base de titanio.

Biofilm formation and acyl homoserine lactone production in Hafnia alvei isolated from raw milk

The objective of this study was to detect the presence of acyl homoserine lactones (AHLs), signal molecules of the quorum sensing system in biofilm formed by Hafnia alvei strains. It also evaluated the effect of synthetic quorum sensing inhibitors in biofilm formation. AHLs were assayed using well diffusion techniques, thin layer chromatography (TLC) and detection directly in biofilm with biomonitors. The extracts obtained from planktonic and sessile cell of H. alvei induced at least two of three monitor strains evaluated. The presence of AHLs with up to six carbon atoms was confirmed by TLC. Biofilm formation by H. alvei was inhibited by furanone, as demonstrated by 96-well assay of crystal violet in microtitre plates and by scanning electron microscopy. The H. alvei 071 hall mutant was deficient in biofilm formation. All these results showed that the quorum sensing system is probably involved in the regulation of biofilm formation by H. alvei.

Ensayo de inmunogenicidad y toxicidad local del cocleato de Neisseriameningitidis en ratas Sprague Dawley / Study of immunogenicity and local toxicity of the Neisseria meningitidis cochleate in Sprague Dawley rats

Los estudios de tolerancia local para productos vacunales resultan fundamentales como requisitos regulatorios para los estudios preclínicos. En este ensayo se utilizaron 48 ratas Sprague Dawley, de ambos sexos, con un peso corporal de 180-220 g, suministradas por el Centro Nacional para la Producción de Animales de Laboratorio, y una duración de 17 días. Las ratas fueron distribuidas en 5 grupos: 3 con diferentes concentraciones de cocleatos, uno sin inocular y otro que recibió el diluente del producto en prueba. A estas se les realizaron las observaciones clínicas necesarias, tales como: mediciones de incremento de peso, consumo de alimentos y agua, así como la evaluación anatomopatológica en los dos tiempos de sacrificio, uno a los 12 y otro a los 17 días; se enfatizó en el estudio histopatológico de encéfalo y las fosas nasales en tres niveles de su extensión. Se hicieron investigaciones inmunológicas consistentes en la determinación de IgG en suero, saliva y líquido cefalorraquídeo. Los resultados arrojaron un incremento del peso. En el consumo de agua y alimento no se observaron alteraciones clínicas, la anatomopatología evidenció discretos cambios inflamatorios que guardaron una relación directa con el aumento de las concentraciones del producto, los títulos de IgG en la saliva y suero de las ratas inoculadas con los cocleatos difirieron de forma significativa (P < 0,05) respecto a los grupos controles, el líquido cefalorraquídeo resultó negativo a la presencia de anticuerpos específicos IgG. Se concluye que los cocleatos aplicados por esta vía en ratas resultaron inmunogénicos e inocuos para el referido producto(AU)

Local Tolerance studies for vaccine products are a main link in the chain of Regulatory Requirements for toxicological preclinical studies. Mainly considering that the use of mucosal road seems to be a current tendency due to the advantages it offers. Sprague Dawley rats of both sexes weighing 100-120 g (reception weight) provided by CENPALAB with the corresponding certificates of sanitary and genetic quality were used in this test. Local tolerance study lasted 17 days. Rats were distributed in 5 groups (3 groups with different cochleate concentrations, one without inoculation and another one that received the diluents of the product in test. Measurement of weight increase, food and water consumption, as well as the anatomopathologic studies in the two times of sacrifice, at 12 and 17 days were performed. Main histopathological studies were carried out in brain and nasal nostrils in three levels of their extension (anterior, medium and posterior areas). In addition, immunological assays such as the determination of IgG in serum, saliva and cerebrospinal fluid (CSF) were carried out. Results showed a sustained weight increase. There were no clinical alterations during water and food consumption, while the existence of discreet acute inflammatory changes was found by anatomopathological studies, which were directly related to the increase of the product concentration. The presence of IgG antibodies in saliva and in sera of the rats inoculated with the cochleates showed significant differences (P <0.05) compared to the non inoculated control group and to the animals inoculated with the diluent. CSF studies resulted negative regarding the presence of specific IgG antibodies. The existence of a direct relation among the concentrations of the product in test and the inflammatory processes in the medium and posterior levels of the nasal nostril was proven, therefore it is considered that cochleates applied by this route and in the concentrations ...(AU)

Evaluación de la toxicidad por dosis única de la vacuna antitetánica vax-TET en ratas Sprague Dawley / Evaluation of toxicity by single dose of the tetanus vaccine vax-TET in Sprague Dawley rats

La vacuna vax-TET® está indicada en la prevención del tétanos y es efectiva si se logra un completo y apropiado esquema de inmunización. Para investigar el potencial tóxico de este producto se realizó una prueba toxicológica con una dosis única, por vía intramuscular, en un volumen de 0,2 mL en ratas Sprague Dawley. La composición de la vacuna de ensayo probada fue la misma de la vacuna comercial. Los animales fueron observados diariamente en buscade síntomas locales y sistémicos de toxicidad. Se realizaron mediciones del consumo de agua y alimento, así como del peso corporal. Dos semanas después de la inoculación las ratas fueron sacrificadas por métodos de eutanasia sin dolor y sometidas a necropsia. No se observaron muertes ni síntomas de toxicidad en los animales estudiados. Tampoco se encontraron diferencias de interés toxicológico entre los grupos experimentales en cuanto a las variables medidas. El estudio anatomopatológico reveló la presencia de formaciones granulomatosas de tipo macrofágico asociadas, fundamentalmente, al hidróxido de aluminio. Estos resultados permitieron concluir que, bajo las condiciones delestudio y según los criterios establecidos, esta vacuna no produce efectos adversos en el modelo animal usado, por lo que se considera potencialmente no tóxica para humanos(AU)

The tetanus vaccine vax-TET® is indicated for the prevention of tetanus and it is effective if a complete and adequate immunization scheme is achieved. In order to investigate the toxic potential of this product, a toxicological test at single dose(0,2 ml), by intramuscular route was developed in Sprague Dawley rats using the same substance concentrations suggested by the manufacturer. The animals were daily observed looking for local and systemic symptoms of toxicity. Water and food consumption and body weight were also monitored during the experiment. Two weeks after inoculation, rats were slaughteredand submitted to necropsy studies. No deaths or toxicity symptoms were observed in the animals studied. No differences of toxicological interest were found among experimental groups regarding the variables measured. The anatomic-pathological study showed the presence of granulomatous formations mainly associated to aluminium hydroxide in the formulation. It wasconcluded that under the study conditions and following the established criteria, this vaccine does not produce any adverse reactions in the animal model used, suggesting a low potential toxicity in humans(AU)

Evaluación de la toxicidad por dosis única de la vacuna antidiftérica-antitetánica en ratas Sprague-Dawley / Evaluation of toxicity by single dose of the Diphtheria-Tetanus Vaccine in SpragueDawley rats

En el presente ensayo se evaluó la toxicidad por dosis única de la vacuna antitetánica antidiftérica (VA-DIFTET®) en ratas Sprague-Dawley. Para ello se utilizó la vía intramuscular por ser la propuesta a usar en humanos. Se administraron 0,3 mL de la vacuna o sus componentes a un total de 20 animales por grupo (10 de cada sexo). Los mismos se observaron diariamente: se midió el consumo de agua y alimento en días alternos y se determinó el peso corporal con intervalos semanales. Se incluyó el análisis anatomopatológico de los animales al final del estudio. Ninguno murió durante el ensayo ni se observaron síntomas clínicos. No hubo diferencias estadísticamente significativas (p>0,1) en cuanto al consumo de agua, alimentos y el peso corporal. En el estudio anatomopatológico se observaron lesiones granulomatosas macrofágicas en las ratas tratadas con la vacuna o con el placebo, hallazgo este característico delas vacunas adyuvadas con hidróxido de aluminio. Los resultados sugirieron que la vacuna VADIFTETes potencialmente inocua al administrar la dosis única por vía intramuscular(AU)