1,720,979 research outputs found
Acute toxicity test of CuO nanoparticles using human Mesenchymal Stem Cells
No full textDespite the growing interest in nanoparticles (NPs), standardized procedures for the evaluation of their toxicity have not been defined. The risk of human exposure is rapidly increasing and reliable toxicity test systems are urgently needed. In vitro methods are ideal in toxicology research because they can rapidly provide reproducible results while preventing the use of animals. Recently, a new test for acute toxicity based on the use of human bone marrow mesenchymal stem cells (hBMMSCs) has been developed and successfully tested in our laboratory following the Interagency Coordinating Committee on the Validation of Alternative Methods guidelines. Along these lines, the aim of this study is to evaluate the acute cytotoxicity of copper oxide (CuO) NPs using the new toxicity test based on hBMMSCs. Our results show that CuO NPs are much more toxic compared to micrometer ones. Specifically, CuO NP exposure exhibits a significant cytotoxicity at all the concentrations used, with an IC50 value of 2.5 ± 0.53 μg/ml. On the other hand, CuO microsized particle exposure exhibits a very low cytotoxicity at the same concentrations, with an IC50 value of 72.13 ± 16.2 μg/ml
GC-MS metabolomics analysis of mesenchymal stem cells treated with copper oxide nanoparticles
No full textHuman exposure to copper oxide (CuO) nanoparticles (NPs) is rapidly increasing and for this reason reliable toxicity test systems are urgently needed. Recently, the acute cytotoxicity of CuO NPs using the new toxicity test based on human bone marrow mesenchymal stem cells (hBMMSCs) has been evaluated. It was shown that CuO NPs are much more toxic when compared to CuO microparticles (MPs). Several studies associate CuO toxicity to a possible alteration of reactive oxygen species (ROS) system. Unluckily, the mechanism that causes the toxicity is still not clear. In this work, the polar metabolite pool of treated cells, at the corresponding IC50 value, for CuO micro and NPs has been studied by gas chromatography coupled to mass spectrometry (GC-MS) and multivariate statistical data analysis. By the same means, differences due to different treatments, on samples, were investigated. Results of discriminant analysis were considered with the aim of finding the relevant metabolites unique for each class. Serine, glyceric acid, and succinic acid were upregulated on samples treated with CuO microparticles, while glutamine was the only discriminant metabolite for the class of samples treated with nanoparticles
Decellularized ovine arteries as small-diameter vascular grafts
No full textAtherosclerosis and its complications still represent the leading cause of death in the developed countries. While autologous blood vessels may be regarded as the best solution for peripheral and coronary bypass, they are unavailable in most patients. Even though tissue engineering techniques are often applied to the development of small-diameter vascular grafts, limiting factors of this approach are represented by the lack of essential extracellular matrix proteins and/or poor biomechanical properties of the scaffolds used. Along these lines, the aim of this study was to develop a decellularization protocol for ovine carotids to be used as suitable small-diameter vascular grafts. Samples were treated either with sodium dodecyl sulphate (SDS) or with Trypsin and Triton X-100; a final nuclease digestion was performed for both protocols. Morphological analyses demonstrate complete removal of nuclei and cellular components in treated vessels, also confirmed by significant reduction in wall thickness and DNA content. Essential extracellular matrix proteins such as collagen, elastin, and fibronectin are well preserved after decellularization. From a mechanical point of view, Trypsin and Triton X-100 treated arteries show elastic modules and compliance comparable to native carotids, whereas the use of SDS makes samples stiffer, with a significant decrease in the compliance mean value and an increase in longitudinal and circumferential Young's modules. It is demonstrated that the treatment where Trypsin and Triton X-100 are combined guarantees complete decellularization of carotids, with no significant alteration of biomechanical and structural properties, thus preserving a suitable environment for adhesion, proliferation, and migration of cells
Evaluation of the use of human mesenchymal stem cells for acute toxicity tests.
No full textIn vitro cytotoxicity tests are typically carried out with transformed, immortalized cell lines or primary cells. Immortalized cells are readily available and easily maintained, although they usually show anomalous behavior and phenotypes, which do not reflect the mechanisms observed in their normal homologous cells. Primary cells are indeed considered a better option as model systems for predicting toxicological behavior, although they are limited in quantity and suffer from batch-to-batch variation due to the need to isolate them freshly for each study. In particular, human Mesenchymal Stem Cells (hMSCs) have never been adopted in order to develop in vitro model systems for acute toxicity tests of chemicals. Therefore, the aim of this study was to verify the possibility of using hMSCs as an alternative method to estimate in vivo starting dose for acute toxicity. As suggested by ICCVAM, 12 reference chemicals were assessed in the present study and a Neutral Red Uptake assay was performed. It is shown for the first time that MSCs isolated from human bone marrow can be confidently used in this area of toxicology. MSCs represent a good promise for the development of in vitro human assays and could ultimately replace, improve or overtake current predictive models in toxicology
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Experimental analysis and modelling of in vitro HUVECs proliferation in the presence of various types of drugs
No full textIn-vitro behavior of different fully dense calcium phosphate materials fabricated by Spark Plasma Sintering
No full textResults obtained during in-vitro experiments concerning human osteoblasts cultivated on the surface of dense samples produced by Spark Plasma Sintering from three types of hydroxyapatite powders are described and discussed. The sintered products display diverse composition and microstructures which are found to significantly influence the biological response of the cells. Osteoblasts adhesion, viability and proliferation are quantitatively comparable for the three classes of bioceramics, whereas matrix mineralization occurs only in products exclusively consisting of hydroxyapatite. Correspondingly, a calcium-phosphate layer exhibiting a trabecular-like microstructure is deposited on the materials surface. Matrix mineralization is favored when the substrate is composed of submicrometer-sized apatite grains. On the other hand, the latter phenomena is markedly suppressed, and so does the formation of the new apatite phase, when cells are seeded on sintered disks composed of Î2-Tri-Calcium Phosphate, which was formed during the sintering process from the decomposition of initial apatite
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