Transiciones microestructurales inducidas por cizalla en sistemas acuosos de un tensioactivo catiónico tipo esterquat

Se presenta un estudio basado en técnicas reológicas y de microscopía electrónica de barrido de bajas temperaturas (cryo-SEM) sobre los cambios de microestructura provocados por el flujo en cizalla de dispersiones acuosas de un tensioactivo catiónico tipo esterquat. Se comparan micrografías de cryo-SEM y las respuestas bajo cizalla oscilatoria de dispersiones sin y con cloruro de calcio. Esta última no presenta zona de comportamiento viscoelástico lineal, apuntando su respuesta no lineal a un fenomeno de estructuracion inducida por cizalla. Ensayos transitorios de inicioal flujo, entre 0,1s -1 y 2000s-1, confirman que se producen aumentos de viscosidad más acusados con el tiempo de flujo a medida que aumenta la velocidad de cizalla. La téecnica de cryo-SEM apoya que los resultados transitorios se deben a que un exceso de energía mecánica provoca transiciones de bicapas de tensioactivo a vesículas. Diferentes ensayos reológicos realizados en serie avalan la naturaleza irreversible, en la escala de tiempo de esta investigación, de las transiciones microestructurales inducidas por cizalla. Se demuestra que a pesar de la presencia de cloruro de calcio (0,1%), la aplicación de una velocidad de cizalla excesiva puede dar lugar a la aparición de respuestas viscoelasticas lineales significativas

Biomaterials for Cardiac Tissue Engineering

Semiotics / semiolog

Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies

By reducing energy density, low-energy sweeteners (LES) might be expected to reduce energy intake (EI) and body weight (BW). To assess the totality of the evidence testing the null hypothesis that LES exposure (versus sugars or unsweetened alternatives) has no effect on EI or BW, we conducted a systematic review of relevant studies in animals and humans consuming LES with ad libitum access to food energy. In 62 of 90 animal studies exposure to LES did not affect or decreased BW. Of 28 reporting increased BW, 19 compared LES with glucose exposure using a specific ‘learning’ paradigm. Twelve prospective cohort studies in humans reported inconsistent associations between LES use and Body Mass Index (-0.002 kg/m2/year, 95%CI -0.009 to 0.005). Meta-analysis of short- term randomized controlled trials (RCTs, 129 comparisons) showed reduced total EI for LES- versus sugar-sweetened food or beverage consumption before an ad libitum meal (-94 kcal, 95%CI -122 to -66), with no difference versus water (-2 kcal, 95%CI -30 to 26). This was consistent with EI results from sustained intervention RCTs (10 comparisons). Meta-analysis of sustained intervention RCTs (4 weeks to 40 months) showed that consumption of LES versus sugar led to relatively reduced BW (nine comparisons; -1.35 kg, 95%CI –2.28 to - 0.42), and a similar relative reduction in BW versus water (three comparisons; -1.24 kg, 95%CI –2.22 to -0.26). Most animal studies did not mimic LES consumption by humans, and reverse causation may influence the results of prospective cohort studies. The preponderance of evidence from all human RCTs indicates that LES do not increase EI or BW, whether compared with caloric or non-caloric (e.g., water) control conditions. Overall, the balance of evidence indicates that use of LES in place of sugar, in children and adults, leads to reduced EI and BW, and possibly also when compared with water

Estudio de la no participación en el programa de prevención de cáncer de mama en la ciudad de Valencia

ResumenObjetivoConocer los motivos de no participación de las mujeres en el Programa poblacional de Prevención de Cáncer de Mama.MétodosEs un estudio observacional transversal, en mujeres que fueron invitadas para participar en el Programa de Prevención de Cáncer de Mama en la ciudad de Valencia y no acudieron. Se realizó una entrevista con cuestionario en el domicilio con 25 preguntas, agrupadas en: conocimiento sobre el programa, motivos de la no participación, actitudes o creencias y características de las encuestadas (variables socioeconómicas, culturales y edad). Se analizaron las diferencias en las características de las mujeres con un análisis bivariante y multivariante mediante regresión logística.ResultadosSe utilizaron 783 direcciones, se obtuvieron 411 cuestionarios, y analizaron 361, y se excluyeron del análisis los 50 cuestionarios utilizados en la prueba piloto, ya que ésta produjo una modificación del cuestionario. El 93,4% (intervalo de confianza [IC] del 95%: 3-95,7) recordaba haber recibido una citación. El motivo principal de no participación fue estar estudiada por otros servicios sanitarios en el 48,8% (IC del 95%: 43,6-53,9), seguido de diversos motivos personales en el 16,1% (IC del 95%: 12,3-19,9) y del horario de citación que no les resultó adecuado en el 15,5% (IC del 95%:11,8-19,2). Analizando la clase social media y alta frente a la clase baja, se observan importantes diferencias: las mujeres de clase media o alta tenían mayor probabilidad de conocer el programa y llevar tratamiento hormonal sustitutivo (THS) y el motivo principal de no asistencia era el estar estudiada por otros servicios sanitarios y para las mujeres de la clase baja el temor, no considerarlo importante para su salud y problemas de accesibilidad horaria. En el análisis multivariante las variables que entraron en el modelo fueron: THS, la clase social y el nivel cultural; de tal forma que aquellas mujeres de clase social media o alta, que llevan THS y de nivel cultural medio o alto tienen mayor probabilidad de estar estudiadas.ConclusionesEl perfil de las mujeres que no participan, pertenece, por un lado, a la clase social media o alta, que toman THS y que están siendo revisadas por otros servicios sanitarios, y por otro, a un grupo de mujeres con nivel socioeconómico bajo y cuyo motivo de no participación es por temor o dificultades de horario.AbstractAimTo determine the reasons for non-participation of women in a breast cancer screening program.MethodsWe performed an observational, cross-sectional study in women who were invited to participate in the breast cancer screening program in the city of Valencia and who failed to attend. The women were interviewed in their homes through a questionnaire consisting of 25 questions grouped as follows: knowledge of the program, reasons for nonparcitipation, attitudes or beliefs and characteristics of the interviewees (socioeconomic and educational variables and age). A descriptive analysis was performed. Differences in the characteristics of women were evaluated thorugh bivariate analysis. Multivariate analysis was performed through logistic regression.ResultsA total of 783 addreses were used, 411 questionnaires were completed and 361 were analyzed. The 50 questionnaires used in the pilot study were excluded because, as a consequence of this study, the questionnaire had been modified. Most of the women (93,4%) (CI: 90.3-95.7) remembered having an appointment. The main reason for not attending was being screened in another health service in 48.8% (CI: 43.6-53.9), followed by various personal reasons in 16.1% (CI: 12.3-19.9) and inability to keep the appointment at the specified time in 15.5% (CI: 11.8-19.2). Comparison of women in the middle and upper social classes with those in the lower classes revealed important differences. Middle and upper class women had a higher probability of knowing about the program and of being on hormone replacement therapy (HRT) and the most frequent reason for non-attendance was attendance at another program run by another health service. In lower class women the reasons for non-attendance were fear, not believing the program to be important to health and inability to keep the appointment at the specified time. In the multivariate analysis, the variables that entered the model were HRT, social class and education. Thus, middle or upper class women undergoing HRT and with secondary or higher education had a higher probability of being screened.ConclusionsThe profile of non-participating women belongs on the one hand to those in the middle or upper social classes, undergoing HRT and being screened by other health services and, on the other, to a group of women of low social class, whose reason for non-participation is fear and timetable difficulties

The influence of dietary lipid composition on skeletal muscle mitochondria from mice following eight months of calorie restriction

PMCID: PMC4138957.-- et al.Calorie restriction (CR) has been shown to decrease reactive oxygen species (ROS) production and retard aging in a variety of species. It has been proposed that alterations in membrane saturation are central to these actions of CR. As a step towards testing this theory, mice were assigned to 4 dietary groups (control and 3 CR groups) and fed AIN-93G diets at 95 % (control) or 60 % (CR) of ad libitum for 8 months. To manipulate membrane composition, the primary dietary fats for the CR groups were soybean oil (also used in the control diet), fish oil or lard. Skeletal muscle mitochondrial lipid composition, proton leak, and H2O2 production were measured. Phospholipid fatty acid composition in CR mice was altered in a manner that reflected the n-3 and n-6 fatty acid profiles of their respective dietary lipid sources. Dietary lipid composition did not alter proton leak kinetics between the CR groups. However, the capacity of mitochondrial complex III to produce ROS was decreased in the CR lard compared to the other CR groups. The results of this study indicate that dietary lipid composition can influence ROS production in muscle mitochondria of CR mice. It remains to be determined if lard or other dietary oils can maximize the CRinduced decreases in ROS production. © 2014 Institute of Physiology v.v.i.This work was supported by the National Institutes of Health grants R01 AG028125 and P01 AG025532.Peer Reviewe

Saturday night purpura: An uncommon presentation of exercise-induced vasculitis

Exercise-induced vasculitis (EIV) is a benign cutaneous vasculitis that affects healthy individuals. We report a case of EIV in a 15-year-old male patient with a striking clinical appearance triggered by a combination of prolonged standing and disco dancing in a warm environment. Pediatric dermatologists should be aware of this activity as a possible trigger of EIV, especially in teenagers

Are we training our novices towards quality 2D profiles for 3D models?

In the history-based, feature-based, parametric CAD approach, 2D profile sketches are the basis for 3D models. Fully-constraining profiles is mandatory to create robust profiles. At present, neither CAD applications nor Model Quality Testing Tools usually check whether 2D profiles contain redundant constraints. Besides, our experience shows that novices tend to introduce redundant constraints. We hypothesize that 2D profiles over-constrained with redundant relations are more difficult to edit than those that avoid redundancies. In the present work―and as a first step to demonstrate this hypothesis―an experiment was conducted. Students of the subject “Graphics engineering” were taught on the creation of constrained 2D profiles. Then, they were asked two questions. On the one hand, novices had to identify and reason whether a simple given profile was fully-constrained, over-constrained or under-constrained. On the other hand, they had to identify and point out the types of the constraints. The results showed that in spite that novices received a specific training, roughly half of them failed to say if the 2D profile sketch was fully-constrained and which type of constraints it contained. Furthermore, the results of the second question revealed that more than the half of students did not recognize perpendicularity as a geometric constraint. As future work, we will try to demonstrate whether a reinforced training through simple exercises and a quick and effective feedback, will allow novices to improve the identification and removal of redundant 2D constraints when drawing 2D profile sketches (thus helping to produce robust profiles)

EFFECT OF DISSOLVED ORGANIC MATTER ON COPPER BIOAVAILABILITY TO A COASTAL DINOFLAGELLATE

Metal complexation by dissolved organic matter (DOM) is considered to decrease metal bioavailability by lowering the free metal ion concentration, therefore protecting organisms from the deleterious effects of metals (Campbell et al., 2002). In coastal lagoons like Mar Menor, with high terrestrial influence and low exchange with open sea, the levels of both DOM and metals are one or two orders of magnitude higher than in open-waters. In order to verify the free ion activity model (FIAM), copper internalization by Prorocentrum micans, a cosmopolitan dinoflagellate also present in the Mar Menor, was tested in the absence and presence of two types of DOM, commercially available fulvic acids from riverine origin (SRFA) and coastal DOM obtained by ultrafiltration (UF-DOM). The microalgae were exposed to artificial sea water enriched with increasing amounts of Cu65 isotope, at levels from 5 to 100 nM Cu, solely and in combination with DOM. After one-hour exposure, samples were centrifuged and washed and pellets were digested with nitric acid at 90ºC, following Sánchez-Marín et al (2010) and Croteau and Luoma (2005). In parallel, careful measurements of metal complexation by anodic stripping voltammetry (ASV) were performed and total Cu concentrations were measured by ICP-MS. Preliminary results show that copper internalization by the microalgae increases linearly as a function of labile Cu, both in the absence and presence of DOM, in agreement with FIAM and with labile Cu measurements performed by ASV. Future work might include testing the influence of competing metals, such as Pb or Zn, on Cu internalization, and to study Cu bioavailability in natural samples collected in the Mar Menor, in order to shed light into the factors that control Cu bioavailability in coastal lagoons