Las crónicas Griegas y la entrada de los Rusos en la historia

Se supone que el Povest vremennyj let es el testimonio más antiguo de la cronística rusa que conservamos. Tanto sus fuentes como su ideología revelan su deuda con las crónicas griegas, pero también se trata de una obra muy original. Un acercamiento a la primera parte de la crónica, una especie de "introducción" a la historia universal desde la creación del mundo hasta la historia rusa propiamente dicha, pone de manifiesto algunos aspectos importantes de los géneros historiográficos medievales, de las relaciones culturales y políticas entre la Rus de Kíev y el Imperio bizantino, y de la formación de la identidad rusa.The Povest vremmenykh let is supposed the most ancient Russian chronicle. Both its sources and ideology reveal the debt to Greek chronicles, but it is really original as well. An approach to the first part of the chronicle, a kind of "introduction" to universal history from the creation of the world to the very Russian history, will show some important aspects of the medieval historiographicaI genres, the cultural and political relations between the Kievan Rus and the Byzantine Empire and the formation of Russian identity

La clasificación semántica de los adjetivos en griego clásico (I)

Los intentos de elaborar una clasificación de los adjetivos en griego se han visto obstaculizados por la heterogeneidad de los criterios manejados. La naturaleza semántica del adjetivo puede explicar algunas de sus peculiaridades sintácticas, por lo que cabe proponer una clasificación semántica basada en el criterio funcional de la alternancia entre coordinación y yuxtaposición, según el cual se coordinan las clases funcionalmente equivalentes y se yuxtaponen las que no lo son. El resultado es una clasificación abierta constituida por once clases funcionales a las que los adjetivos no se adscriben de forma unívoca, sino dependiendo de los contextos. Las clases centrales engloban los contenidos más objetivos (cualidad inherente y no inherente, color, materia, procedencia y ubicación), mientras que en los extremos de la escala se sitúan los más subjetivos (valoración, dimensión, propósito, característica típica...)

Las crónicas greigas y la entrada de los rusos en la historia

The Povest vremmenykh let is supposed the most ancient Russian chronicle. Both its sources and ideology reveal the debt to Greek chronicles, but it is really original as well. An approach to the first part of the chronicle, a kind of “introduction” to universal history from the creation of the world to the very Russian history, will show some important aspects of the medieval historiographical genres, the cultural and political relations between the Kievan Rus and the Byzantine Empire and the formation of Russian identity.Se supone que el Povest vremennyj let es el testimonio más antiguo de la cronística rusa que conservamos. Tanto sus fuentes como su ideología revelan su deuda con las crónicas griegas, pero también se trata de una obra muy original. Un acercamiento a la primera parte de la crónica, una especie de “introducción” a la historia universal desde la creación del mundo hasta la historia rusa propiamente dicha, pone de manifiesto algunos aspectos importantes de los géneros historiográficos medievales, de las relaciones culturales y políticas entre la Rus de Kíev y el Imperio bizantino, y de la formación de la identidad rusa

H2O2-preconditioned human adipose-derived stem cells (HC016) increase theirresistance to oxidative stress byoverexpressing Nrf2 and bioenergetic adaptation

BackgroundMesenchymal stem cells, including those derived from human adipose tissue (hASCs), are currently being widely investigated for cell therapy. However, when transplanted at the site of injury, the survival and engraftment rates of hASCs are low, mainly due to the harsh microenvironment they encounter, characterized by inflammation and oxidative stress. To overcome these therapeutic limitations, cell preconditioning with low-concentration of hydrogen peroxide (H2O2) has been proposed as a plausible strategy to increase their survival and adaptation to oxidative stress. Nonetheless, the underlying mechanisms of this approach are not yet fully understood. In this study, we analyzed molecular and bioenergetic changes that take place in H2O2 preconditioned hASCs.MethodsLong-term exposure to a low concentration of H2O2 was applied to obtain preconditioned hASCs (named HC016), and then, their response to oxidative stress was analyzed. The effect of preconditioning on the expression of Nrf2 and its downstream antioxidant enzymes (HO-1, SOD-1, GPx-1, and CAT), and of NF-kappa B and its related inflammatory proteins (COX-2 and IL-1 beta), were examined by Western blot. Finally, the Seahorse XF96 Flux analysis system was used to evaluate the mitochondrial respiration and glycolytic function, along with the total ATP production.ResultsWe found that under oxidative conditions, HC016 cells increased the survival by (i) decreasing intracellular ROS levels through the overexpression of the transcription factor Nrf2 and its related antioxidant enzymes HO-1, SOD-1, GPx-1, and CAT; (ii) reducing the secretion of pro-inflammatory molecules COX-2 and IL-1 beta through the attenuation of the expression of NF-kappa B; and (iii) increasing the total ATP production rate through the adaption of their metabolism to meet the energetic demand required to survive.ConclusionsH(2)O(2) preconditioning enhances hASC survival under oxidative stress conditions by stimulating their antioxidant response and bioenergetic adaptation. Therefore, this preconditioning strategy might be considered an excellent tool for strengthening the resistance of hASCs to harmful oxidative stress.Partial funding for this project was provided by the Department of Economic Development and Competitiveness of the Basque Government, the European Regional Development Fund (PREMISE IG-2015/0000558), and the University of the Basque Country (UPV/EHU; research grants PES 17/29 and 16/37)

Hydrogen Peroxide-Preconditioned Human Adipose-Derived Stem Cells Enhance the Recovery of Oligodendrocyte-Like Cells after Oxidative Stress-Induced Damage

Oxidative stress associated with neuroinflammation is a key process involved in the pathophysiology of neurodegenerative diseases, and therefore, has been proposed as a crucial target for new therapies. Recently, the therapeutic potential of human adipose-derived stem cells (hASCs) has been investigated as a novel strategy for neuroprotection. These cells can be preconditioned by exposing them to mild stress in order to improve their response to oxidative stress. In this study, we evaluate the therapeutic potential of hASCs preconditioned with low doses of H2O2 (called HC016 cells) to overcome the deleterious effect of oxidative stress in an in vitro model of oligodendrocyte-like cells (HOGd), through two strategies: i, the culture of oxidized HOGd with HC016 cell-conditioned medium (CM), and ii, the indirect co-culture of oxidized HOGd with HC016 cells, which had or had not been exposed to oxidative stress. The results demonstrated that both strategies had reparative effects, oxidized HC016 cell co-culture being the one associated with the greatest recovery of the damaged HOGd, increasing their viability, reducing their intracellular reactive oxygen species levels and promoting their antioxidant capacity. Taken together, these findings support the view that HC016 cells, given their reparative capacity, might be considered an important breakthrough in cell-based therapies.Partial funding for this project was provided by the Department of Economic Development and Competitiveness of the Basque Government, the European Regional Development Fund (PREMISE IG-2015/0000558) and the University of the Basque Country (UPV/EHU; research grants GIU 19/088 and PES 17/29 and 16/37)

Conditioned Medium from H2O2-Preconditioned Human Adipose-Derived Stem Cells Ameliorates UVB-Induced Damage to Human Dermal Fibroblasts

Human skin exposure to ultraviolet B (UVB) radiation can result in acute photodamage through oxidative modifications of cellular components and biomolecules involved in the metabolism of dermal cells. Recently, the therapeutic potential of human adipose-derived stem cells (hASCs) has been investigated as a novel strategy for photoprotection due to their pro-angiogenic properties, protective activity against oxidative stress and paracrine effect on dermal cells. To enhance these therapeutic properties, hASCs can be preconditioned by exposing them to sublethal cellular stressors. In this study, we first analyzed response capacity against UVB-induced oxidative stress in H2O2-preconditioned hASCs (called HC016 cells); and second, we evaluated the photoprotective effect of HC016-conditioned medium (CM) in an in vitro UVB irradiation model in cultured human foreskin fibroblasts (hFFs). The results demonstrated that HC016 cells have a greater capacity to respond efficiently to UVB-induced oxidative stress, evidenced by higher Nrf2 antioxidant system activity and enhanced viability and migration capacity. Further, HC016-CM treatment increased viability, migratory capacity and collagen type I synthesis in hFFs exposed to UVB radiation, as well as reducing their cytotoxicity, apoptosis, senescence and IL-6 secretion. Collectively, these findings support the view that HC016 cells could protect against UVB-induced photodamage via paracrine mechanisms.This research was founded by the University of the Basque Country (UPV/EHU, grant reference numbers: GIU19/088 and PES 21/50)