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Search Results: 1 - 10 of 5631 matches for " Diana Fiorentini "
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Dietary Phenolic Acids Act as Effective Antioxidants in Membrane Models and in Cultured Cells, Exhibiting Proapoptotic Effects in Leukaemia Cells
Laura Zambonin,Cristiana Caliceti,Francesco Vieceli Dalla Sega,Diana Fiorentini,Silvana Hrelia,Laura Landi,Cecilia Prata
Oxidative Medicine and Cellular Longevity , 2012, DOI: 10.1155/2012/839298
Abstract: Caffeic, syringic, and protocatechuic acids are phenolic acids derived directly from food intake or come from the gut metabolism of polyphenols. In this study, the antioxidant activity of these compounds was at first evaluated in membrane models, where caffeic acid behaved as a very effective chain-breaking antioxidant, whereas syringic and protocatechuic acids were only retardants of lipid peroxidation. However, all three compounds acted as good scavengers of reactive species in cultured cells subjected to exogenous oxidative stress produced by low level of H2O2. Many tumour cells are characterised by increased ROS levels compared with their noncancerous counterparts. Therefore, we investigated whether phenolic acids, at low concentrations, comparable to those present in human plasma, were able to decrease basal reactive species. Results show that phenolic acids reduced ROS in a leukaemia cell line (HEL), whereas no effect was observed in normal cells, such as HUVEC. The compounds exhibited no toxicity to normal cells while they decreased proliferation in leukaemia cells, inducing apoptosis. In the debate on optimal ROS-manipulating strategies in cancer therapy, our work in leukaemia cells supports the antioxidant ROS-depleting approach.
Effect of Plasma Membrane Cholesterol Depletion on Glucose Transport Regulation in Leukemia Cells
Cristiana Caliceti, Laura Zambonin, Cecilia Prata, Francesco Vieceli Dalla Sega, Gabriele Hakim, Silvana Hrelia, Diana Fiorentini
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0041246
Abstract: GLUT1 is the predominant glucose transporter in leukemia cells, and the modulation of glucose transport activity by cytokines, oncogenes or metabolic stresses is essential for their survival and proliferation. However, the molecular mechanisms allowing to control GLUT1 trafficking and degradation are still under debate. In this study we investigated whether plasma membrane cholesterol depletion plays a role in glucose transport activity in M07e cells, a human megakaryocytic leukemia line. To this purpose, the effect of cholesterol depletion by methyl-β-cyclodextrin (MBCD) on both GLUT1 activity and trafficking was compared to that of the cytokine Stem Cell Factor (SCF). Results show that, like SCF, MBCD led to an increased glucose transport rate and caused a subcellular redistribution of GLUT1, recruiting intracellular transporter molecules to the plasma membrane. Due to the role of caveolae/lipid rafts in GLUT1 stimulation in response to many stimuli, we have also investigated the GLUT1 distribution along the fractions obtained after non ionic detergent treatment and density gradient centrifugation, which was only slightly changed upon MBCD treatment. The data suggest that MBCD exerts its action via a cholesterol-dependent mechanism that ultimately results in augmented GLUT1 translocation. Moreover, cholesterol depletion triggers GLUT1 translocation without the involvement of c-kit signalling pathway, in fact MBCD effect does not involve Akt and PLCγ phosphorylation. These data, together with the observation that the combined MBCD/SCF cell treatment caused an additive effect on glucose uptake, suggest that the action of SCF and MBCD may proceed through two distinct mechanisms, the former following a signalling pathway, and the latter possibly involving a novel cholesterol dependent mechanism.
Steviol Glycosides Modulate Glucose Transport in Different Cell Types
Benedetta Rizzo,Laura Zambonin,Cristina Angeloni,Emanuela Leoncini,Francesco Vieceli Dalla Sega,Cecilia Prata,Diana Fiorentini,Silvana Hrelia
Oxidative Medicine and Cellular Longevity , 2013, DOI: 10.1155/2013/348169
Abstract: Extracts from Stevia rebaudiana Bertoni, a plant native to Central and South America, have been used as a sweetener since ancient times. Currently, Stevia extracts are largely used as a noncaloric high-potency biosweetener alternative to sugar, due to the growing incidence of type 2 diabetes mellitus, obesity, and metabolic disorders worldwide. Despite the large number of studies on Stevia and steviol glycosides in vivo, little is reported concerning the cellular and molecular mechanisms underpinning the beneficial effects on human health. The effect of four commercial Stevia extracts on glucose transport activity was evaluated in HL-60 human leukaemia and in SH-SY5Y human neuroblastoma cells. The extracts were able to enhance glucose uptake in both cellular lines, as efficiently as insulin. Our data suggest that steviol glycosides could act by modulating GLUT translocation through the PI3K/Akt pathway since treatments with both insulin and Stevia extracts increased the phosphorylation of PI3K and Akt. Furthermore, Stevia extracts were able to revert the effect of the reduction of glucose uptake caused by methylglyoxal, an inhibitor of the insulin receptor/PI3K/Akt pathway. These results corroborate the hypothesis that Stevia extracts could mimic insulin effects modulating PI3K/Akt pathway. 1. Introduction Stevia rebaudiana Bertoni is a weak perennial shrub belonging to Asteraceae (Compositae) family, native to subtropical regions of Brazil and Paraguay. Its leaves have been used as a sweetener since ancient times and for many other medicinal purposes in Latin America and the Orient for centuries [1, 2]. The “sweet herb” has gained increasing interest from nutritional researchers and commercial area in the last years, due to the growing need to find new natural calorie-free sweeteners alternative to sugar. Indeed, in both industrialized and developing countries, the incidence of type 2 diabetes mellitus and obesity is sharply increasing as a result of dietary behaviours, reduced physical activities, and ageing. These metabolic disorders have become major public health problems worldwide [3, 4]. Glycemic control is fundamental to the management of diabetes since it is associated with significantly decreased rates of retinopathy, nephropathy, neuropathy, and cardiovascular disease, the most common cause of death in diabetic patients. The effort to achieve near-normoglycemia through the key strategy of glycemic control includes recommendations for prevention and control of diabetes, for example, monitoring carbohydrate intake and limiting the consumption
Mobilità umana e qualità dell'informazione: il ruolo dei centri di documentazione
Barbara Fiorentini
m@gm@ , 2003,
Abstract: In tema di interculturalità e di mobilità umana in Italia si stanno diffondendo numerosi centro di documentazione. In genere si tratta di strutture di supporto ad enti o associazioni che già operano nel settore e che necessitano di strumenti di informazione e di formazione ... Quindi un Centro di documentazione dedicato all'interculturalità e alla mobilità umana si profila non come un semplice deposito di notizie, bensì un Centro in grado di trasformare informazioni, spesso parziali, in materiali organicamente ricomposti e più facilmente leggibili. Inoltre dovrebbe proporsi di fornire un efficiente e aggiornato servizio divulgativo e di promuovere uno spazio di studio e di lavoro.
Formazione e nuove tecnologie: la formazione a distanza
Barbara Fiorentini
m@gm@ , 2003,
Abstract: Per formazione a distanza (FAD) si intendono tutti gli ambienti educativi in cui i momenti dell'insegnamento e dell'apprendimento sono spazialmente e/o temporalmente separati ed in cui il processo formativo prevede servizi di supporto all'apprendimento. La storia della FAD segue l'evoluzione delle tecnologie di comunicazione, partendo dai corsi per corrispondenza, passando per l'emissione televisiva e arrivando alle più recenti strutture di teleconferenza satellitare. Infatti la reale innovazione nel campo della FAD avviene con l'introduzione delle reti telematiche e di internet. L'insegnamento a distanza on line permette e stimola l'interazione e la collaborazione tra i partecipanti. La FAD in rete condivide con la formazione tradizionale l'interazione di gruppo, con il vantaggio della libertà da vincoli temporali e spaziali.
A Pesquisa e as Práticas de Forma o de Professores de Matemática em face das Políticas Públicas no Brasil Research and Practices on Mathematics Teacher Education in face of the Public Policies in Brazil
Dario Fiorentini
Bolema: Boletim de Educa??o Matemática , 2008,
Abstract: Este artigo pretende p r em evidência algumas políticas públicas brasileiras no campo da educa o e analisar os desdobramentos e impactos das mesmas sobre cursos, programas e processos de forma o de professores que ensinam matemática. O foco da análise incide principalmente sobre os cursos de licenciatura e pedagogia, os cursos emergenciais de forma o em servi o, os processos de sele o de professores para o ensino público e alguns programas de forma o continuada de professores. Para desenvolver a análise s o tomados como referência alguns estudos brasileiros que tematizam as políticas públicas educacionais no Brasil engendradas sob um regime de política econ mica neo-liberal e algumas pesquisas desenvolvidas pelo Grupo de Estudo e Pesquisa sobre Forma o de Professores de Matemática (GEPFPM) da FE/Unicamp. O artigo conclui sobre a necessidade da SBEM mobilizar a comunidade de educadores matemáticos, tentando estabelecer parcerias com outras entidades científicas e institui es congêneres, de modo a participar e intervir com responsabilidade e compromisso na concep o e gest o das políticas educacionais do Brasil. Palavras-chave: Forma o de Professores de Matemática. Políticas Públicas. Políticas Educacionais. Licenciatura em Matemática. Forma o em Servi o de Professores. This paper intends to highlight some Brazilian public policies in the field of education and analyze their impact on courses, programs and processes of mathematics teacher education. The analysis focuses mainly on: teaching degree courses; in-service education courses; teachers’ selection processes for public teaching; and some continuing education programs for teachers. To develop this analysis, some Brazilian studies that deal with educational public policies in Brazil are used as references. These policies are engendered under a regime of neo-liberal economic policies. Some research developed by the Study & Research Group on Mathematics Teacher Education (GEPFPM) of FE/Unicamp is also used as reference. This paper ends highlighting the need of SBEM to mobilize the mathematics educators community to establish partnerships with other scientific entities and similar institutions, aiming at participating and intervening in the conception and administration of public education policies in our country with responsibility and commitment. Keywords: Mathematics Teacher Education. Public Policies. Educational Policies. Preservice Teacher Education. In-service Teacher Education.
Nuclear astrophysics and neutrinos
G. Fiorentini
Physics , 1998,
Abstract: In this report, centered on the activities within the MURST-PRIN project "Fisica teorica del nucleo e dei sistemi a pi\`u corpi" we discuss recent advances on the following items: i)neutrinos as probes of the solar interior and of other astrophysical objects; ii)neutrinos as probes of physics beyond the Standard Model of electroweak interactions; iii)the role of nuclear physics in i) and ii); iv) who is doing what within the italian network; v)future projects.
Origin of the efficient light emission from inversion domain boundaries in GaN
V. Fiorentini
Physics , 2002, DOI: 10.1063/1.1554776
Abstract: Intentionally-produced inversion domain boundaries in GaN have been reported to be highly efficient recombination centers. Here I report a rationale for this phenomenon based on ab initio density-functional calculations. I also propose a model, based on the existence of polarization in GaN, of the observation that a domain boundary acts as a rectifying junction under voltage applied between the two opposite-polarity surfaces.
Conceitos de arquitetura manutente e de arquitetura voltária
Jarbas Karman,Domingos Fiorentini
Exacta , 2006,
Abstract: To situate, with property, the nosocomial architecture, so that we can differ it from the other architectures, we use the concepts of manutente (unalterable, immutable) and voltária (mutable, fickle) architectures, developed by the authors. Whereas manutente refers to a finished, enduring architecture, which stands stable over the years, basically like in its original project, voltária refers to an unfinished, provisory, dynamic, mutable architecture. Each one of this concepts congregates characteristics which are peculiar and inherent to them; with regard to the medical care establishments, so that they survive and endure efficaciously, they must be provided, beforehand, since their creation, of provisory means and resources which assure the flexibility and the necessary resources to keep them up-to-dated and in conditions to contrapose the physical and functional obsolescence omnipresent in health institutions. The nosocomial architecture disposes of basic requirements that confers to the draftsman the necessary tools to provide the required functionality and competitiveness to the health institutions. Flexibility is one of them. The text focuses some of its aspects and illustrates some of the practical applications.
Solar neutrinos (almost) without standard solar models
G. Fiorentini,B. Ricci
Physics , 1995,
Abstract: We extract information on the fluxes of Be and CNO neutrinos directly from solar neutrino experiments, with minimal assumptions about solar models. Next we compare these results with solar models, both standard and non standard ones. Finally we discuss the expectations for Borexino, both in the case of standard and non standard neutrinos.
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