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•New chitosan hydrogels with silver nanoparticles and ampicillin were prepared.•Antibiofilm activity against multidrug-resistant pathogens is reported.•New chitosan hydrogels are a ...strategy for biofilm control having low cytotoxicity.•Potential to prevent colonization and thrombosis on central venous catheter is studied.
The purpose of this study was to generate novel chitosan hydrogels (CHs) loaded with silver nanoparticles (AgNPs) and ampicillin (AMP) to prevent early formation of biofilms. AgNPs and CHs were characterized by UV-Vis, DLS, TEM, rheology, FT-IR, Raman, and SEM. The antibiofilm effect of the formulations was investigated against four multidrug-resistant and extensively drug-resistant pathogens using a colony biofilm, a high cell density and gradients model. Also, their hemostatic properties and cytotoxic effect were evaluated. Rheology results showed that CHs with AgNPs and AMP are typical non-Newtonian pseudoplastic fluids.
The CH with 25 ppm of AgNPs and 50 ppm AMP inhibited the formation of biofilms of Acinetobacter baumannii, Enterococcus faecium and Staphylococcus epidermidis, while a ten-fold increase of the antimicrobial’s concentration was needed to inhibit the biofilm of the β-lactamase positive Enterobacter cloacae. Further, CH with 250 ppm of AgNPs and 500 ppm AMP showed anticoagulant effect, and it was shown that all formulations were biocompatible. Besides to previous reports that described the bioadhesion properties of chitosan, these results suggest that AgNPs and AMP CHs loaded could be used as prophylactic treatment in patients with central venous catheter (CVC), inhibiting the formation of biofilms in their early stages, in addition to their anticoagulant effect and biocompatibility, those properties could keep the functionality of CVC helping to prevent complications such as sepsis and thrombosis.
We measured the distance between fluorescent-labeled DNA loci of various interloci contour lengths in Caulobacter crescentus swarmer cells to determine the in vivo configuration of the chromosome. ...For DNA segments less than about 300 kb, the mean interloci distances, 〈 r 〉, scale as n ⁰.²², where n is the contour length, and cell-to-cell distribution of the interloci distance r is a universal function of r/n ⁰.²² with broad cell-to-cell variability. For DNA segments greater than about 300 kb, the mean interloci distances scale as n , in agreement with previous observations. The 0.22 value of the scaling exponent for short DNA segments is consistent with theoretical predictions for a branched DNA polymer structure. Predictions from Brownian dynamics simulations of the packing of supercoiled DNA polymers in an elongated cell-like confinement are also consistent with a branched DNA structure, and simulated interloci distance distributions predict that confinement leads to “freezing” of the supercoiled configuration. Lateral positions of labeled loci at comparable positions along the length of the cell are strongly correlated when the longitudinal locus positions differ by <0.16 μm. We conclude that the chromosome structure is supercoiled locally and elongated at large length scales and that substantial cell-to-cell variability in the interloci distances indicates that in vivo crowding prevents the chromosome from reaching an equilibrium arrangement. We suggest that the force causing rapid transport of loci remote from the parS centromere to the distal cell pole may arise from the release at the polar region of potential energy within the supercoiled DNA.
Green roofs (GRs) are a feasible solution for mitigating increased runoff volumes in urban areas. Though many studies have focused their analysis on the quantity and quality of GR runoff, with ...respect to the relevance of specific site conditions in GR performance, the information gathered for the tropical Andes is not sufficient. This study assessed the hydrological performance and runoff water quality of 12 green roof modular systems located at the Universidad de los Andes campus (Bogotá, Colombia). Based on 223 rainfall events spanning a 3-year period, average rainfall retention was 85% (coefficient of variation = 29%). t-tests, the Welch Test, multiple linear regressions, and correlation analysis were performed in order to assess the potential effect of air temperature, substrate type, vegetation cover, relative humidity, antecedent dry weather period (ADWP), rainfall duration, and rainfall maximum intensity. In some cases, GR design variables (i.e., substrate type and vegetation cover) were found to be significant for describing rainfall retention efficiencies and, depending on the GR type, some hydrological variables were also correlated with rainfall retention. Rainfall and GR runoff from 12 rainfall events were also monitored for total Kjeldahl nitrogen (TKN), nitrates, nitrites, ammonia, total phosphorus (TP), phosphates, pH, total dissolved solids (TDS), total suspended solids (TSS), color, turbidity, biological oxygen demand (BOD), chemical oxygen demand (COD), total coliforms, metals (i.e., zinc, copper, nickel, lead, selenium, aluminum, barium, boron, calcium, strontium, iron, lithium, magnesium, manganese, potassium, sodium), and polyaromatic hydrocarbons (PAHs). The results obtained confirmed that GR systems have the ability to neutralize pH, but are a source of the rest of the aforementioned parameters, excluding PAHs (with concentrations below detection limits), ammonia, TSS, selenium and lithium, where differences with control cases (rainfall and plastic panel runoff) were not statistically significant. Substrate type, event size, and rainfall regime are relevant variables for explaining runoff water quality.
In situations where breastfeeding is impractical, milk formulas have emerged as the primary choice for infant nutrition. Numerous global studies have scrutinized the fluoride content in these ...formulas, uncovering fluctuations in fluoride levels directly associated with the method of preparation. This variability poses a potential risk of elevated fluoride concentrations and, consequently, an increased susceptibility to dental fluorosis in infants. The primary objective of this review is to intricately delineate the fluoride content in dairy formulas and emphasize the variability of these values concerning their reconstitution process. The review's findings reveal that, among the 17 studies assessing fluoride levels in infant formula, milk-based formulas exhibit a range of 0.01-0.92 ppm, with only two studies exceeding 1.30 ppm. Conversely, soy-based formulas demonstrate values ranging from 0.13-1.11 ppm. In conclusion, the observed variability in fluoride levels in infant formulas is ascribed to the choice of the water source employed in the preparation process. This underscores the paramount importance of meticulously adhering to recommendations and guidelines provided by healthcare professionals concerning the utilization of these formulas and their meticulous reconstitution.
Este artículo reporta el estudio de las variables subyacentes al estrés académico en dos poblaciones diferenciadas de estudiantes citadinos que cursan asignaturas de Física en instituciones de ...educación superior (Colombia y México). El inventario utilizado es el de Polo, Hernández y Pozo (1996), el cual mide dos dimensiones: respuestas al estrés y actividades que producen estrés. Se ha considerado una dimensión adicional que considera aspectos propios de la clase de Física. La población de estudiantes universitarios que participaron en cada comunidad fue de 124 por país. El instrumento tiene una confiabilidad de 0,918 (Col) y 0,937 (Mxn); la medida de adecuación muestral de Kaiser-Meyer-Olkin fue de 0,838 (Col) y 0,878 (Mxn); la varianza interpretada 61,40 % (Col) y 64,46 % (Mxn). Los resultados muestran cuatro variables subyacentes a la población de estudiantes en Colombia (respuestas al estrés RE, interacción I, la evaluación E y actividad escolar extra AEE); en tanto que en México hay tres variables subyacentes al estrés (respuestas al estrés RE, la evaluación E y entorno escolar EE). Las respuestas al estrés tienen diferencias entre las poblaciones. La evaluación, al igual que otros estudios, se muestra como una variable que subyace al estrés académico en ambas poblaciones; sin embargo, su comprensión muestra diferentes fuentes.
El Programa de Formación Permanente de docentes propuesto por elIDEP significa un cambio morfológico en las bases académicas de la formación . Este es un paso importante dentro de una nueva visión ...movilizadora de la educación en un contexto urbano. En este sentido, la dinámica organizativa y académica del PFPD permitirá la aparición de grupos de investigación asociados a diversos intereses. demandas y necesidades de los diferentes campos de la docencia.
La necesidad de preparar un maestro de alto nivel académicocapaz de generar nuevas relaciones con la sociedad y la culturamoderna, la importancia de que dicho maestro construya nuevasrelaciones con ...el conocimiento -la ciencia y la tecnología-, elinterés de hacer del campo pedagógico un auténtico campointelectual moderno, evidencian la importancia de consolidar elSistema Nacional de Formación de Docentes (S.N.F.D.)
Pluronic P105 micelles are potential candidates as chemotherapy drug delivery vehicles using ultrasonic stimulation as a release trigger. Acoustic power has been previously shown to release two ...anthracycline agents from these polymeric carriers. In this study, an ultrasonic exposure chamber with fluorescence detection was used to examine the mechanism of doxorubicin release from P105 micelles. Acoustic spectra were collected and analyzed, at the same spatial position as fluorescence data, to probe the role of cavitation in drug release. Our study showed a strong correlation between percent drug release and subharmonic acoustic emissions, and we attribute the drug release to collapse cavitation that perturbs the structure of the micelle and releases drug.
We aimed to comment on the methodological differences and applications of these three types of reviews with special attention to Latin America. Among these new types of reviews we have the scoping ...review, umbrella review and focused mapping review synthesis. Scoping reviews identify the nature and extent of the evidence, umbrella reviews focus on the synthesis of all systematic reviews that address the same health problem, while focused mapping review syntheses are valid options when a classical mapping of the evidence is not feasible, due to addressing too many articles. As researchers in Latin America become familiar with the methodology and usefulness of these new types of review, an increase in scientific production will be observed.
Actualmente, los nanomateriales son de gran interés para la ciencia y la tecnología, debido a que sus propiedades físicas, químicas y mecánicas pueden ajustarse de acuerdo con su dimensionalidad, lo ...que se ve reflejado en la mejora de su rendimiento si se compara con los materiales en bulto o de mayor escala. Otra ventaja de los nanomateriales es que pueden adoptar diversas morfologías, dependiendo del método de fabricación utilizado. Hoy en día existen diferentes técnicas de fabricación de nanomateriales. En este trabajo se utilizó la técnica de anodización para obtener nanovarillas de CuOH, debido a que, comparado con otras técnicas, la anodización no requiere de equipos costosos o sistemas de alta complejidad. Para la obtención de nanovarillas de CuOH se construyó una celda electrolítica formada por láminas de cobre al 99.9 % de pureza, calibre de 0.3 mm y un área de 3 cm2 como ánodo; se empleó además una barra cilíndrica de grafito de 6 mm de diámetro como cátodo y una solución de hidróxido de potasio (KOH) con una concentración 3 M como electrolito. Se fabricó un total de 21 muestras utilizando tiempos de 2 a 8 minutos. Un par de muestras representativas se estudiaron por microscopia electrónica de barrido (MEB) para identificar la morfología presente en las láminas anodizadas y 7 muestras se estudiaron por espectroscopía Raman. Por MEB se corroboró la presencia de nanovarillas; se identificó que el largo y el espesor de las nanoestructuras es de aproximadamente 10 µm y 200 nm respectivamente. Además, se logró apreciar que las nanovarillas están compuestas de nanohilos que tienen un espesor de 50 nm aproximadamente. Por microscopia Raman se determinó que las nanovarillas están compuestas de CuOH y se encontró una tendencia clara en el incremento de la intensidad de las señales Raman asociadas al CuOH, conforme incrementa el tiempo de anodización.
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