1,721,005 research outputs found
Amniotic Fluid and Placental Membranes as Sources of Stem Cells: Progress and Challenges
Full text linkThe intention of this special edition is to collect review and original research articles that illustrate and stimulate growing efforts to understand the implication of perinatal stem cells in pathological conditions such as cardiovascular and metabolic diseases and inflammatory, autoimmune, musculoskeletal, and degenerative diseases [...
Effect of sulforaphane on aquaporin-8 in a leukemic cell line
No full textCancer cells are characterized by an increase in spatially localized reactive oxygen species (ROS) production and by an altered redox environment compared to normal cells. Consequently, signalling pathways that promote cell proliferation, survival, angiogenesis and metastasis are hyper-activated. In particular, hydrogen peroxide (H2O2) derived from NOX family is involved in various redox signal transduction pathways and the aquaporin 8 (AQP8) has been identified as a H2O2 transport facilitator across the plasma membrane. Recent evidence demonstrated that many tumor cell types express elevated level of aquaporin isoforms and highlighted a positive correlation between histological tumor grade and the AQP expression.
Sulforaphane (SFN), an isothiocyanate compound present in abundance in cruciferous vegetables, has been found to induce therapeutic effects against a wide array of malignancies in both experimental and epidemiological studies .
Therefore, this study aimed at the evaluation of the potential effect of SFN on the modulation of AQP8, NOX2 and p-VEGFR-2 expression in B1647 cell line, a model of acute myeloid leukemia. In fact, we previously demonstrated that AQP8 funnels NOX-derived H2O2, triggered by endogenously generated VEGF, which, in turn, provokes VEGFR-2 phosphorylation and the consequent modulation of many cellular activities, resulting in cell survival and proliferation. As peroxiredoxin (Prx1) represents a member of the so called thiol-based antioxidant system that acts as redox switches to modulate redox signalling pathways, the effect of SFN on Prx1 expression was also evaluated.
Unravelling the role of AQP8 in cancer redox signalling, and the effect exerted by SFN on its modulation, can offer new potential target for anti-cancer therapy, suggesting the importance of dietary co-treatment
Natural compounds as a strategy to optimize “in vitro” expansion of stem cells
Full text linkThe efficient use of stem cells for transplantation is often limited by the relatively low numbers of stem cells collected. The ex vivo expansion of human stem cells for clinical use is a potentially valuable approach to increase stem cell number. Currently, most of the procedures used to expand stem cells are carried out using a 21% oxygen concentration, that is about 4- to 10-fold greater than the concentration characteristic of their natural niches. Hyperoxia might cause oxidative stress with a deleterious effect on the physiology of cultured stem cells. In this review, we investigate and critically examine the available information on the ability of natural compounds to counteract hyperoxia-induced damage in different type of stem cells ex vivo. In particular, we focused on proliferation and stemness maintenance in an attempt to draw up useful indications to define new culture media with a promoting activity on cell expansion in vitro
Natural antioxidants to improve cell culture conditions of amniotic fluid stem cells
No full textHuman amniotic fluid stem cells (AFSCs) are a powerful source of cells with a plethora of trophic and immunomodulatory functions. These cells can be appropriately expanded ex-vivo to be differentiated in many cell types, in order to dissect developmental pathways, unravel pathogenic mechanisms and replace defective tissues. Traditionally, in vitro AFSCs are exposed to non-physiological concentrations of O2 increasing the production of reactive oxygen species (ROS). The unbalance in the redox signals may impair the AFSC stemness machinery1. In this context the use of natural antioxidants could be proposed as a strategy to prevent the loss of self-renewal and the extensive cellular damage due to abnormal ROS production. To this aim, AFSCs were exposed to sulphorafane (SF) and epigallo-3-catechingallate (EGCG) to counteract ROS deleterious effects.
AFSCs were co-treated with 1 M SF and 10 M EGCG. After 72 h a slight increase in their metabolic activity was observed. However, cell population doubling over a cell culture period of 25 days was not different between untreated and co-treated samples. Interestingly, the co-treatment with SF and EGCG synergistically reduced intracellular ROS level in respect to SF or EGCG treatment alone, as measured by DCFH-DA assay. In addition, co-treated AFSCs displayed higher total GSH level in respect to the untreated samples. Self-renewal capacity was investigated evaluating the expression of pluripotent gene markers such as OCT4, NANOG and SOX2 by RT-PCR. Interestingly, the co-treatment was able to up-regulate the expression of all the three genes. Moreover, the chronic treatment for 21 days with SF and EGCG counteracted the expected decrease of OCT4 and NANOG expression during cell passaging.
In conclusion, we propose the co-treatment with SF and EGCG as a strategy to counteract oxidative stress and maintain the functionality of AFSCs
Nuclear Nox4-derived reactive oxygen species in myelodysplastic syndromes
Full text linkA role for intracellular ROS production has been recently implicated in the pathogenesis and progression of a wide variety of neoplasias. ROS sources, such as NAD(P)H oxidase (Nox) complexes, are frequently activated in AML (acute myeloid leukemia) blasts and strongly contribute to their proliferation, survival, and drug resistance. Myelodysplastic syndromes (MDS) comprise a heterogeneous group of disorders characterized by ineffective hematopoiesis, with an increased propensity to develop AML. The molecular basis for MDS progression is unknown, but a key element in MDS disease progression is the genomic instability. NADPH oxidases are now recognized to have specific subcellular localizations, this targeting to specific compartments for localized ROS production. Local Nox-dependent ROS production in the nucleus may contribute to the regulation of redox-dependent cell growth, differentiation, senescence, DNA damage, and apoptosis. We observed that Nox1, 2, and 4 isoforms and p22phox and Rac1 subunits are expressed in MDS/AML cell lines and MDS samples, also in the nuclear fractions. Interestingly, Nox4 interacts with ERK and Akt1 within nuclear speckle domain, suggesting that Nox4 could be involved in regulating gene expression and splicing factor activity. These data contribute to the elucidation of the molecular mechanisms used by nuclear ROS to drive MDS evolution to AML
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Enhancing stem cell functionality through antioxidant supplementation
No full textAmniotic fluid stem cells (AFSCs) are characterized in vivo by a particular niche allowing their unique role in the body. Maintaining the functionality of stem cells ex vivo for clinical applications is essential. Cellular redox status plays an important role in stem cell biology as long the adverse effects by reactive oxygen species (ROS) are excluded. Aim of our study was to investigate the protective effect of two antioxidants, sulforaphane (SF) and epigallocathechin gallate (EGCG), against oxidative stress occuring during in vitro AFSC culture. The co- treatment with SF and EGCG was effective in reducing ROS production, increasing GSH levels and enhancing the endogenous antioxidant defences through the up-regulation of glutathione reductase, NAD(P)H:quinone oxidoreductase-1 and thioredoxin reductase. Intriguingly, the co- treatment sustained the stemness state by up-regulating pluripotency markers and influenced senescence associated markers. The co-treatment promoted osteogenic differentiation and up- regulated osteogenic genes. In conclusion, SF and EGCG can be used in combination in AFSC culture as a strategy to preserve stem cell functionality
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