Selenium Compounds Affect Differently the Cytoplasmic Thiol/Disulfide State in Dermic Fibroblasts and Improve Cell Migration by Interacting with the Extracellular Matrix.

Deficient wound healing is frequently observed in patients diagnosed with diabetes, a clinical complication that compromises mobility and leads to limb amputation, decreasing patient autonomy and family lifestyle. Fibroblasts are crucial for secreting the extracellular matrix (ECM) to pave the wound site for endothelial and keratinocyte regeneration. The biosynthetic pathways involved in collagen production and crosslinking are intimately related to fibroblast redox homeostasis. In this study, two sets of human dermic fibroblasts were cultured in normal (5 mM) and high (25 mM)-glucose conditions in the presence of 1 µM selenium, as sodium selenite (inorganic) and the two selenium amino acids (organic), Se-cysteine and Se-methionine, for ten days. We investigated the ultrastructural changes in the secreted ECM induced by these conditions using scanning electron microscopy (SEM). In addition, we evaluated the redox impact of these three compounds by measuring the basal state and real-time responses of the thiol-based HyPer biosensor expressed in the cytoplasm of these fibroblasts. Our results indicate that selenium compound supplementation pushed the redox equilibrium towards a more oxidative tone in both sets of fibroblasts, and this effect was independent of the type of selenium. The kinetic analysis of biosensor responses allowed us to identify Se-cysteine as the only compound that simultaneously improved the sensitivity to oxidative stimuli and augmented the disulfide bond reduction rate in high-glucose-cultured fibroblasts. The redox response profiles showed no clear association with the ultrastructural changes observed in matrix fibers secreted by selenium-treated fibroblasts. However, we found that selenium supplementation improved the ECM secreted by high-glucose-cultured fibroblasts according to endothelial migration assessed with a wound healing assay. Direct application of sodium selenite and Se-cysteine on purified collagen fibers subjected to glycation also improved cellular migration, suggesting that these selenium compounds avoid the undesired effect of glycation.

Biological Redox Impact of Tocopherol Isomers Is Mediated by Fast Cytosolic Calcium Increases in Living Caco-2 Cells.

Most of the biological impacts of Vitamin E, including the redox effects, have been raised from studies with α-tocopherol only, despite the fact that tocopherol-containing foods carry mixed tocopherol isomers. Here, we investigated the cellular mechanisms involved in the immediate antioxidant responses evoked by α-, γ- and δ-tocopherol in Caco-2 cells. In order to track the cytosolic redox impact, we performed imaging on cells expressing HyPer, a fluorescent redox biosensor, while cytosolic calcium fluctuations were monitored by means of Fura-2 dye and imaging. With this approach, we could observe fast cellular responses evoked by the addition of α-, γ- and δ-tocopherol at concentrations as low as 2.5 µM. Each isomer induced rapid and consistent increases in cytosolic calcium with fast kinetics, which were affected by chelation of extracellular Ca2+, suggesting that tocopherols promoted a calcium entry upon the contact with the plasma membrane. In terms of redox effects, δ-tocopherol was the only isomer that evoked a significant change in the HyPer signal at 5 µM. By mimicking Ca2+ entry with ionomycin and monensin, a decline in the HyPer signal was induced as well. Finally, by silencing calcium with 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), an intracellular Ca2+ chelator, none of the isomers were able to induce redox changes. Altogether, our data indicate that an elevation in cytoplasmic Ca2+ is necessary for the development of a tocopherol-induced antioxidant impact on the cytoplasm of Caco-2 cells reported by HyPer biosensor.

Tratamiento nutricional en úlceras por presión y úlceras venosas / Nutritional treatment in pressure and venous ulcers

RESUMEN Las úlceras por presión (UPP) y úlceras venosas (UV) son frecuentes en adultos y adultos mayores. En Chile un 70% de las heridas crónicas corresponden a UV y la prevalencia de UPP en pacientes hospitalizados es de 28%. El objetivo de esta revisión es analizar la evidencia disponible respecto al tratamiento nutricional de individuos con UPP y UV. Estas úlceras tienen diferentes etiologías, pero ambas provocan un aumento de requerimientos energéticos, proteicos y de micronutrientes. La cicatrización de heridas depende de varios factores como: el tipo de úlcera, estado nutricional, patologías presentes, el tipo de curación y el tratamiento médico. La terapia nutricional establece en la mantención o aumento de peso de estos pacientes, administración adecuada de proteínas y suplementación de energía, proteínas o micronutrientes cuando se presente déficit.

ABSTRACT Pressure and venous ulcers are common in adults and the elderly. In Chile, 70% of chronic wounds correspond to venous ulcers and the prevalence of pressure ulcers in hospitalized patients is 28%. The aim of this review was to analyze the available evidence regarding the nutritional treatment of individuals with pressure and venous ulcers. These ulcers have different etiologies, but both produce an increase in energy, protein, and micronutrient requirements. The healing of wounds depends on several factors such as the type of ulcer, nutritional status, current co-morbidities, healing type and medical treatment. Nutritional therapy should be based on weight maintenance or gain of these patients, adequate administration of proteins and energy supplementation, or protein or micronutrients when a deficiency occurs.

Variación estacional del perfil lipídico en adultos aparentemente sanos de Santiago, Chile / Seasonal variations in the lipid profile of apparently healthy young adults living in Santiago, Chile.

El perfil lipídico depende de muchos factores. Sin embargo, las variaciones estacionales de estos componentes han sido escasamente establecidas en el hemisferio sur. El objetivo de este estudio fue determinar la variación estacional del perfil lipídico por un periodo de un año en un grupo de adultos aparentemente sanos de Santiago, Chile. El diseño del estudio fue observacional y prospectivo. Participaron en el estudio 50 voluntarios sanos de ambos sexos y de edades entre 23 a 62 años. En forma mensual y durante un año se midió el perfil lipídico. LDL fue significativamente mayor en invierno y primavera que en verano (p<0,01). Por el contrario HDL disminuye en invierno (p<0,05). Se concluye que existen variaciones estacionales en los niveles séricos de LDL y HDL. El patrón circanual está caracterizado por mayores niveles de LDL en invierno y primavera y menores niveles de HDL en invierno.

The lipid profile is impacted by numerous factors. However, the seasonal variations in this profile have not been well-established in the southern hemisphere. The aim of this study was to determine the seasonal variation of the lipid profile in apparently healthy adults from Santiago, Chile. The study design was observational and prospective, involving 50 healthy volunteers of both genders, aged 23-62 years. The lipid profile was measured at monthly intervals over the course of one year. LDL was significantly higher in winter -spring than in summer- fall (p <0.01). Conversely, HDL decreases significantly in winter (p<0,05). We conclude that there are seasonal variations in the serum levels of LDL and HDL. The circannual pattern is characterized by increased levels of LDL in winter-spring and low levels of HDL in winter.

[Seasonal variations in the lipid profile of apparently healthy young adults living in Santiago, Chile]. / Variación estacional del perfil lipídico en adultos aparentemente sanos de Santiago, Chile.

The lipid profile is impacted by numerous factors. However, the seasonal variations in this profile have not been well-established in the southern hemisphere. The aim of this study was to determine the seasonal variation of the lipid profile in apparently healthy adults from Santiago, Chile. The study design was observational and prospective, involving 50 healthy volunteers of both genders, aged 23-62 years. The lipid profile was measured at monthly intervals over the course of one year. LDL was significantly higher in winter -spring than in summer- fall (p < 0.01). Conversely, HDL decreases significantly in winter (p < 0.05). We conclude that there are seasonal variations in the serum levels of LDL and HDL. The circannual pattern is characterized by increased levels of LDL in winter-spring and low levels of HDL in winter.