1,721,056 research outputs found
Stem cell distribution and MGMT expression in glioblastoma: Role of intratumoral hypoxic gradient
No full textLetter: Combining 5-Aminolevulinic Acid Fluorescence and Intraoperative Magnetic Resonance Imaging in Glioblastoma Surgery: A Histology-Based Evaluation
No full textL-Proline as a modulator of ectodermal differentiation in ES cells. Focus on "L-Proline induces differentiation of ES cells: a novel role for an amino acid in the regulation of pluripotent cells in culture
No full textThe development of cell therapeutics from embryonic stem (ES) cells will require technologies that direct cell differentiation to specific somatic cell lineages in response to defined factors. The initial step in formation of the somatic lineages from ES cells, differentiation to an intermediate, pluripotent primitive ectoderm-like cell, can be achieved in vitro by formation of early primitive ectoderm-like (EPL) cells in response to a biological activity contained within the conditioned medium MEDII. Fractionation of MEDII has identified two activities required for EPL cell formation, an activity with a molecular mass of 100 M l-proline and some l-proline-containing peptides resulted in changes in colony morphology, cell proliferation, gene expression, and differentiation kinetics consistent with differentiation toward a primitive ectoderm-like cell. This activity appeared to be associated with l-proline since other amino acids and analogs of proline did not exhibit an equivalent activity. Activation of the mammalian target of rapamycin (mTOR) signaling pathway was found to be necessary but not sufficient for l-proline activity; addition of other activators of the mTOR signaling pathway failed to alter the ES cell phenotype. This is the first report describing a role for amino acids in the regulation of pluripotency and cell differentiation and identifies a novel role for the imino acid l-proline
Glioblastoma cancer stem cells: Role of the microenvironment and therapeutic targeting
No full textIt has been recently suggested that many types of cancer, including glioblastoma (GBM), contain functionally subsets of cells with stem-like properties named "cancer stem cells" (CSCs). These are characterized by chemotherapy resistance and considered one of the key determinants driving tumor relapse. Many studies demonstrated that Glioma stem cells (GSCs) reside in particular tumor niches, that are necessary to support their behavior. A hypoxic microenvironment has been reported to play a crucial role in controlling GSC molecular and phenotypic profile and in promoting the recruitment of vascular and stromal cells in order to sustain tumor growth. Recent advances in the field allow researches to generate models able to recapitulate, at least in part, the extreme heterogeneity found within GBM tumors. These models try to account for the presence of GSCs and more differentiated cells, the influence of different microenvironments enclosed within the mass, heterotypic interactions between GBM and stromal cells and genetic aberrations. Understanding the mechanism of action of the microenvironmental signals and the interplay between different cell types within the tumor mass, open new questions on how GSCs modulate GBM aggressiveness and response to therapy. The definition of these tumor features will allow to setup innovative multimodal therapies able to target GBM cells at multiple levels. Here, we will discuss the major advances in the study of GSC role in GBM and the therapeutic implications resulting from them, thus reporting the latest strategies applied to counteract and overcome GBM intrinsic resistance to therapy for a better management of patients. © 2012 Elsevier Inc
Laser Systems and Networks with Organic Nanowires and Nanofibers
No full textThe potentialities of miniaturized laser sources are still far from being fully developed. Unprecedented opportunities are generated in this field by organic nanowires and nanofibers, which can be used as building blocks of micro- and nanolasers in which they combine optical gain, waveguiding, and very high versatility to create nanophotonic networks. The progress in laser devices and network architectures based on optically pumped organic light-emitting nanowires and nanofibers is here presented, with emphasis on developed active materials, fabrication technologies, lasing mechanisms, and cavity geometries, and on achieved device performance in terms of spectral tunability, excitation threshold, and resonator quality factors. Recent examples of optical coupling of different miniaturized lasers, of their application in optical sensing, and of network lasers are presented. Future directions for research are also outlined, which include the exploration of new classes of active organic or hybrid materials within nanowires, the more in-depth characterization of the fundamental properties of these lasers, and the use of topologically defined organic nanophotonics in network science, computing, and diagnostics
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
Role of environmental chemicals, processed food derivatives, and nutrients in the induction of carcinogenesis
No full textIn recent years it has been hypothesized that cancer stem cells (CSCs) are the actual driving force of tumor formation, highlighting the need to specifically target CSCs to successfully eradicate cancer growth and recurrence. Particularly, the deregulation of physiological signaling pathways controlling stem cell proliferation, self-renewal, differentiation, and metabolism is currently considered as one of the leading determinants of cancer formation. Given their peculiar, slow-dividing phenotype and their ability to respond to multiple microenvironmental stimuli, stem cells appear to be more susceptible to genetic and epigenetic carcinogens, possibly undergoing mutations resulting in tumor formation. In particular, some animal-derived bioactive nutrients and metabolites known to affect the hormonal milieu, and also chemicals derived from food processing and cooking, have been described as possible carcinogenic factors. Here, we review most recent literature in this field, highlighting how some environmental toxicants, some specific nutrients and their secondary products can induce carcinogenesis, possibly impacting stem cells and their niches, thus causing tumor growt
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
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