Poly-l/dl-lactic acid films functionalized with collagen IV as carrier substrata for corneal epithelial stem cells

Limbal epithelial stem cells (LESCs) are responsible for the renewal of corneal epithelium. Cultivated limbal epithelial transplantation is the current treatment of choice for restoring the loss or dysfunction of LESCs. To perform this procedure, a substratum is necessary for in vitro culturing of limbal epithelial cells and their subsequent transplantation onto the ocular surface. In this work, we evaluated poly-L/DL-lactic acid 70:30 (PLA) films functionalized with type IV collagen (col IV) as potential in vitro carrier substrata for LESCs. We first demonstrated that PLA-col IV films were biocompatible and suitable for the proliferation of human corneal epithelial cells. Subsequently, limbal epithelial cell suspensions, isolated from human limbal rings, were cultivated using culture medium that did not contain animal components. The cells adhered significantly faster to PLA-col IV films than to tissue culture plastic (TCP). The mRNA expression levels for the LESC specific markers, K15, P63α and ABCG2 were similar or greater (significantly in the case of K15) in limbal epithelial cells cultured on PLA-col IV films than limbal epithelial cells cultured on TCP. The percentage of cells expressing the corneal (K3, K12) and the LESC (P63α, ABCG2) specific markers was similar for both substrata. These results suggest that the PLA-col IV films promoted LESC attachment and helped to maintain their undifferentiated stem cell phenotype. Consequently, these substrata offer an alternative for the transplantation of limbal cells onto the ocular surface.This work was supported by the Carlos III National Institute of Health, Spain (CIBER-BBN and Spanish Network on Cell Therapy, (TerCel RD12/0019/0036), MINECO/FEDER, EU), and the Castilla y León Regional Government, Spain (Regional Center for Regenerative Medicine and Cell Therapy, SAN673/VA/28/08 and SAN126/VA11/09)

Obesity and overweight among the poor and marginalized in rural Mexico: impact analysis of the effect of school breakfasts on children aged five to eleven

This article estimates the effect of the School Breakfast Program (SBP) on overweight and obese Mexican children aged five to eleven living in a poor and marginalized rural context during 2012-2019. Using data from the 2012, 2016, 2018, and 2019 National Health and Nutrition Surveys (ENSANUT), as well as propensity score matching techniques, this research compares the usual food intake of a group of children enrolled on the SBP with a control group that were not. The results indicate that SBP recipients include more overweight children, and that these consume unhealthy foods, including sugary drinks, snacks, sweets, and desserts, more frequently than those in the control group. There was no significant difference in the children’s obesity between the two groups. These findings highlight the need for a more comprehensive school breakfast program, that is connected to the food and nutritional security approach and is designed and implemented according to each Mexican region’s specific alimentary requirements and socioeconomic needs.En este artículo, se analiza el efecto del Programa Desayunos Escolares en niños mexicanos de cinco a once años con sobrepeso y obesidad que viven en un contexto rural pobre y marginado durante 2012 a 2019. Utilizando datos de la Encuesta Nacional de Salud y Nutrición (Ensanut) de 2012, 2016, 2018 y 2019, así como técnicas de emparejamiento por puntaje de propensión, en esta investigación, se compara la ingesta habitual de un grupo de niños inscritos en Programa Desayunos Escolares con otro de control que no lo era. Los resultados indican que, entre los receptores de los Desayunos, se incluyen a más niños con sobrepeso, y que estos consumen alimentos poco saludables, incluidas bebidas azucaradas, bocadillos, dulces y postres, con mayor frecuencia que los del grupo de control. No constó diferencia significativa, sin embargo, en la obesidad de los niños entre los dos grupos. Tales hallazgos resaltan la necesidad de un programa de desayuno escolar más integral, vinculado al enfoque de la seguridad alimentaria y nutricional, y a que se diseñe e implemente de acuerdo con los requerimientos alimentarios y socioeconómicos de cada región de México

UN MODELO CAUSAL DE COMPETITIVIDAD EMPRESARIAL PLANTEADO DESDE LA VBR: CAPACIDADES DIRECTIVAS, DE INNOVACIÓN, MARKETING Y CALIDAD

El propósito de esta investigación es desarrollar un modelo explicativo de la competitividad empresarial a partir de factores internos a la empresa. Para ello se identifican los factores de competitividad más importantes en el caso de las empresas manufactureras vascas, así como las variables que permiten caracterizarlos, utilizando técnicas cualitativas basadas en entrevistas con directivos. Los factores resultantes son las capacidades directivas, las capacidades de innovación, las capacidades de marketing y las capacidades de calidad. Tras analizar estos factores bajo la Visión de la empresa Basada en Recursos (VBR), y definir sus escalas de medida, se plantea un modelo causal que relaciona cada uno de ellos con la competividad de la empresa. Este modelo otorga una importancia especial a las capacidades directivas al plantear este factor como precedente del resto de capacidades de la empresa. El modelo es contrastado a través de la técnica de modelado con ecuaciones estructurales utilizando una muestra representativa de la población de empresas manufactureras vascas formada por 861 empresas

Colloidal Silicon-Germanium Nanorod Heterostructures

Colloidal nanorods with axial Si and Ge heterojunction segments were produced by solution-liquid-solid (SLS) growth using Sn as a seed metal and trisilane and diphenylgermane as Si and Ge reactants. The low solubility of Si and Ge in Sn helps to generate abrupt Si-Ge heterojunction interfaces. To control the composition of the nanorods, it was also necessary to limit an undesired side reaction between the Ge reaction byproduct tetraphenylgermane and trisilane. High-resolution transmission electron microscopy reveals that the Si-Ge interfaces are epitaxial, which gives rise to a significant amount of bond strain resulting in interfacial misfit dislocations that nucleate stacking faults in the nanorods

The transcriptional cycle of HIV-1 in real-time and live cells

RNA polymerase II ( RNAPII) is a fundamental enzyme, but few studies have analyzed its activity in living cells. Using human immunodeficiency virus ( HIV) type 1 reporters, we study real- time messenger RNA ( mRNA) biogenesis by photobleaching nascent RNAs and RNAPII at specific transcription sites. Through modeling, the use of mutant polymerases, drugs, and quantitative in situ hybridization, we investigate the kinetics of the HIV- 1 transcription cycle. Initiation appears efficient because most polymerases demonstrate stable gene association. We calculate an elongation rate of approximately 1.9 kb/ min, and, surprisingly, polymerases remain at transcription sites 2.5 min longer than nascent RNAs. With a total polymerase residency time estimated at 333 s, 114 are assigned to elongation, and 63 are assigned to 3'- end processing and/ or transcript release. However, mRNAs were released seconds after polyadenylation onset, and analysis of polymerase density by chromatin immunoprecipitation suggests that they pause or lose processivity after passing the polyA site. The strengths and limitations of this kinetic approach to analyze mRNA biogenesis in living cells are discussed

Comparison of the material quality of AlxIn1-xN (x ~ 0-0.50) films deposited on Si (100) and (111) by reactive RF sputtering

Here, we compare the material quality of AlxIn1-xN layers deposited on Si with different crystallographic orientations, (100) and (111), via radio-frequency (RF) sputtering. To modulate their Al content, the Al RF power was varied from 0 to 225 W, whereas the In RF power and deposition temperature were fixed at 30 W and 300oC, respectively. X-ray diffraction measurements reveal a c-axis-oriented wurtzite structure with no phase separation regardless of the Al content (x = 0-0.50), which increases with the Al power supply. The surface morphology of the AlxIn1-xN layers improves with increasing Al content and it is similar for samples grown on both Si substrates (the root-mean-square roughness decreases from 12 nm to 2.5 nm). Furthermore, from TEM images we notice a similar grain-like columnar morphology and defect density on samples deposited on both Si substrates under the same conditions. Simultaneously grown AlxIn1-xN-on-sapphire samples point to a residual n-type carrier concentration in the 1020-1021 cm-3 range. The optical band gap energy of these layers evolves from 1.75 eV to 2.56 eV with increasing Al content, consistent with the blue shift of their low-temperature photoluminescence. In general, the material quality of the AlxIn1-xN films on Si is similar for both crystallographic orientations. Nonetheless, samples deposited on sapphire show an improved structural and morphological characteristic likely due to the lower difference in lattice constants between the nitride and the sapphire substrate

Development of sandwich ELISA and lateral flow immunoassay to detect almond in processed food

Almond (Prunus dulcis) represents a potential allergenic hazard that should be included in Allergen Control Plans. In this study, sandwich ELISA and lateral flow immunoassay (LFIA), using amandin (Pru du 6) as the target protein, were developed to detect almond in processed food and validated according to international guides. ELISA could detect 2 ng/mL and LFIA 30 ng/mL of pure amandin. No cross-reactivity was found on a panel of 50 food commodities with the exception of Pecan nut, Brazil nut and chestnut for which the cross-reactivity was lower than 0.02%. Furthermore, ELISA and LFIA were able to detect 0.12 and 0.70 ppm of almond protein in foods spiked with almond extract whereas 0.20 and 2.0 ppm could be detected in baked cookies incurred with almond, respectively. Both techniques could be applied for food manufacturers and control agencies for monitoring the presence of almond traces in food and working surfaces. © 2021 The Author(s