MECANISMOS DE ADHESIÓN AL TRACTO INTESTINAL Y ANTAGONISMO DE Bifidobacterium

El género Bifidobacterium está integrado por bacilos Gram positivos que forman parte de la microflora normal del tracto intestinal de mamíferos. Como probiótico, uno de los beneficios que ofrecen estas bacterias, es inhibir la adhesión de patógenos en el intestino, tanto en humanos como en animales. Sin embargo, el mecanismo no está bien establecido. Las bacterias patógenas poseen proteínas de superficie tipo lectina, llamadas adhesinas, con las que reconocen carbohidratos (receptores) en la mucosa y/o epitelio. Dentro de ese reconocimiento también están involucradas interacciones de tipo hidrofílico e hidrofóbico. Mediante este mecanismo se adhieren y colonizan el tracto intestinal. En los microorganismos probióticos, la presencia de adhesinas, su papel en la colonización y desplazamiento de bacterias patógenas en el intestino empieza a investigarse.Palabras clave: Bifidobacterium, probiotico, tracto intestinalBifidobacterium, probiotic, intestinal trac

Study of Methylene Blue Degradation by Gold Nanoparticles Synthesized within Natural Zeolites

We carried out the in situ synthesis of gold nanoparticles inside a natural clinoptilolite-type zeolite matrix, using ascorbic acid as reducing agent. The microstructure of both zeolite and zeolite-gold nanocomposite was characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and Energy-Dispersive X-ray Spectroscopy (EDS) techniques. Size distribution as assessed by STEM indicated that 60% of gold nanoparticles measured less than 2.5 nm. Determination of the surface area by the BET method revealed a specific value of 27.35 m2/g. The catalytic activity of zeolite-gold regarding methylene blue degradation under different light-exposing conditions was evaluated by UV-Vis spectroscopy. The results indicated that 50% degradation was achieved in only 11 min in presence of sunlight. This reaction was faster in comparison with those obtained using a white LED light. A notable aspect of this study is that catalysis was carried out without the addition of any strong reducing agents, such as sodium borohydride (NaBH4)

BIOCOMPATIBLE SILVER NANOPARTICLES SYNTHESIZED USING RUMEX HYMENOSEPALUS EXTRACT DECREASES FASTING GLUCOSE LEVELS IN DIABETIC RATS

The objective of this study was to evaluate the antihyperglycemic activity of silver nanoparticles (SNPs) produced using green chemistry in a model of stretozotocin (STZ)-induced experimental diabetes in rats. Green SNPs (GSNPs) were synthesized using Rumex hymenosepalus extracts as reducing agent. In control and hyperglycemic rats was performed the measurement of blood glucose levels and glucose tolerance tests. Posteriorly, low dose of GSNPs were administrated in diabetic rats and was evaluated fasting blood glucose and glucose tolerance tests, pre and post-treatment. The basal level of fasting blood glucose of all rats (103.5 ± 4.4 mg/dL) increased after diabetes induction with STZ (315.2 ± 36.1 mg/dL). The treatment with GSNPs during 9 days decreased 50% the blood glucose in diabetic rats. The glucose tolerance test showed that in diabetic rats treated with GSNPs induces a minimal increase in blood glucose. In conclusion, a low dose of GSNPs showed antihyperglycemic activity

Coarse particulate air pollution and daily mortality: A global study in 205 cities.

RATIONALE: The associations between ambient coarse particulate matter (PM2.5-10) and daily mortality is not fully understood at a global scale. OBJECTIVES: To evaluate the short-term associations between PM2.5-10 and total, cardiovascular, and respiratory mortality across multiple countries/regions worldwide. METHODS: We collected daily mortality (total, cardiovascular, respiratory) and air pollution data from 205 cities in 20 countries/regions. Concentrations of PM2.5-10 were computed as the difference between inhalable and fine particulate matter. A two-stage time-series analytic approach was applied, with over-dispersed generalized linear models and multilevel meta-analysis. We fitted two-pollutant models to test the independent effect of PM2.5-10 from co-pollutants (fine particulate matter, nitrogen dioxide, sulfur dioxide, ozone, and carbon monoxide). Exposure-response relationship curves were pooled and regional analyses were conducted. MEASUREMENTS AND MAIN RESULTS: A 10 μg/m3 increase in PM2.5-10 concentration on lag 0-1 day was associated with increments of 0.51% (95% confidence interval [CI]: 0.18%, 0.84%), 0.43% (95%CI: 0.15%, 0.71%) and 0.41% (95%CI: 0.06%, 0.77%) in total, cardiovascular, and respiratory mortality, respectively. The associations varied by country and region. These associations were robust to adjustment by all co-pollutants in two-pollutant models, especially for PM2.5. The exposure-response curves for total, cardiovascular, and respiratory mortality were positive, with steeper slopes at lower exposure ranges and without discernible thresholds. CONCLUSIONS: This study provides novel global evidence on the robust and independent associations between short-term exposure to ambient PM2.5-10 and total, cardiovascular and respiratory mortality, suggesting the need to establish a unique guideline or regulatory limit for daily concentrations of PM2.5-10

Identification, characterization and selection of autochthonous lactic acid bacteria as probiotic for feedlot cattle

Livestock microbiota is becoming a focus of interest for veterinaries, animal nutritionists and microbiologists in view to select beneficial bacteria with impact in health and animal productivity. As resident adapted microorganisms, lactic acid bacteria (LAB) were isolated, identified and characterized from the homologous host to promote their permanence/efficiency acting as additives in feedlot cattle feeding. Cultivable LAB numbers from cattle feces (CF), pens soil (PS) and feed rations (FR) ranged from 5 to 6 log CFU/g during feedlot permanence. Isolates (500) were identified by (GTG)5-PCR and sequence analysis of 16S rRNA, being represented by Enterococcus, Lactobacillus, Leuconostoc, Pediococcus and Weissella genera and 20 different species. Genetic mapping showed that predominant LAB species in CF and PS samples were Lactobacillus (Lb) mucosae (34%), Enterococcus (E) hirae (26%) and E. faecium-durans (20%), while in FR E. faecium-durans (46%), Pediococcus (P). pentosaceous, P. acidilactici (17%) and Lb. acidophilus (11%) were mainly isolated. Surface characterization showed most of LAB as high hydrophilic, however several strains from CF and PS revealed strong hydrophobic and auto-aggregative character with a positive correlation between both superficial properties. Adhesion to polystyrene displayed variable biofilm formation patterns for Enterococcus and Lactobacillus strains depending on the presence of Tween in MRS medium. When antagonistic activity of isolated LAB against bovine relevant pathogens was evaluated, organic acids and hydrogen peroxide production were mostly responsible for inhibition; bacteriocin production was shown only by a Lb. mucosae strain. In addition, tolerance to acid and bile salts showed lactobacilli to withstand GIT conditions, while enterococci were more sensitive to low acid environment. On these bases, several Lactobacillus strains may be selected to explore their potential use as direct fed bacteria in feedlot cattle.Fil: Maldonado, Natalia Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Aristimuño Ficoseco, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Mansilla, Flavia Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Melian, Constanza Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Hebert, Elvira Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Vignolo, Graciela Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin