1,720,988 research outputs found
3D CULTURE OF ARTICULAR CARTILAGE EXPLANTS:NEW PERSPECTIVES FOR FUTURE POSSIBLE CLINICAL APPLICATIONS
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Microfluidic sensor for noncontact detection of cell flow in a microchannel
No full textA microfluidic sensor for detection of cells flowing in a microchannel is presented. The sensor consists of a PDMS (PolyDiMethylSiloxane) layer with two planar microreservoirs connected by a microchannel. The bottom sides of the microreservoirs are faced to two sensing electrodes realized on a PCB (Printed Circuit Board). A noncontact measurement is ensured by an insulator layer between the electrodes and the fluid. Particles flowing in the microchannel cause changes in the conductivity of the narrow path formed by the fluid, producing variations in the impedance between the electrodes. A tailored electronic interface based on a DDS (Direct Digital Synthesis) device is proposed to measure the impedance variations. In the experimental tests, the cell flow is detected by changes in the effective capacitance and conductance between electrodes. These preliminary results are promising for biological measurements such as counting and sizing of cells in different matrices
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
A comparison between the effects of five different inorganic Pb2+ compounds on the proliferation of an epithelial rat liver cell line
No full textExtremely Low-Frequency Electromagnetic Fields Affect Myogenic Processes in C2C12 Myoblasts: Role of Gap-Junction-Mediated Intercellular Communication
Full text linkExtremely low-frequency electromagnetic fields (ELF-EMFs) can interact with biological systems. Although they are successfully used as therapeutic agents in physiatrics and rehabilitative practice, they might represent environmental pollutants and pose a risk to human health. Due to the lack of evidence of their mechanism of action, the effects of ELF-EMFs on differentiation processes in skeletal muscle were investigated. C2C12 myoblasts were exposed to ELF-EMFs generated by a solenoid. The effects of ELF-EMFs on cell viability and on growth and differentiation rates were studied using colorimetric and vital dye assays, cytomorphology, and molecular analysis of MyoD and myogenin expression, respectively. The establishment of functional gap junctions was investigated analyzing connexin 43 expression levels and measuring cell permeability, using microinjection/dye-transfer assays. The ELF-EMFs did not affect C2C12 myoblast viability or proliferation rate. Conversely, at ELF-EMF intensity in the mT range, the myogenic process was accelerated, through increased expression of MyoD, myogenin, and connexin 43. The increase in gap-junction function suggests promoting cell fusion and myotube differentiation. These data provide the first evidence of the mechanism through which ELF-EMFs may provide therapeutic benefits and can resolve, at least in part, some conditions of muscle dysfunction
Structural analysis of rat bone explants kept in vitro in simulated microgravity conditions.
No full textSkeletal abnormalities reported in humans and laboratory animals after spaceflight, include cancellous osteopenia, decreased cortical and cancellous bone formation, aberrant matrix ultrastructure, decreased mineralization and reduced bone strength. Although considerable effort has been made up to now to understand the skeletal effects of spaceflight, in order to estimate health risk, our knowledge in this area is still largely incomplete. It is widely accepted that the mechanical strength of cancellous bone is related not only to the mineral content, but also to the trabecular micro-architecture arrangement. Three-dimensional numerical analysis of bone volumes has been shown to be an important tool in this field. The Cell Method, a recently introduced numerical method, has been applied to static analysis of structures obtained from 3D reconstruction of micro-computed tomography scans performed at the Elettra Synchrotron facility (Trieste, Italy) in order to quantify changes in trabecular bone architecture. In the present study, the Cell Method model is used to compare the micro-tomographed structure of fragments of rats bone explants (tibial proximal epiphyses) harvested after 3 days and after 1, 2, 3 and 4 weeks of culture in the RCCS bioreactor, which represents the unique existing bioreactor, operating on the Earth's surface, capable of successfully reproducing, in vitro, optimal conditions in order to simulate a microgravity environment. Although preliminary, our results seem to suggest that the exposure of tibial bone explants to simulated microgravity conditions obtained by the RCCS bioreactor, are consistent with skeletal changes observed after spaceflight
Advanced 3D Models Cultured to Investigate Mesenchymal Stromal Cells of the Human Dental Follicle
No full textThe human dental follicle (hDF) contains the developing tooth and is involved in regulating tooth maturation and eruption. To investigate the mesenchymal stromal cells of the dental follicle, 2 three-dimensional (3D) culture models were used, based on a dynamic bioreactor: the Rotary Cell Culture System (RCCSTM) and the 3D culture of precursor cells isolated from follicular tissue (human dental follicle cells [hDFCs]). The hDFCs were obtained from impacted third molars of 20 patients. Two 3D culture models were tested. In the first model, intact hDF explants were cultured in 3D conditions, preserving the original tissue architecture; they were studied using histomorphological and molecular analyses. The second model involved the 3D culture of hDFCs, which were characterized to evaluate their multipotency in terms of differentiation capability. Of the biomarkers known to characterize hDFCs, hDF precursors were selected for our study. The immunophenotype and in situ immunocytochemistry were evaluated for markers CD44, CD90, CD146, CD105, CD31, CD34, and CD45 Ag. The results show that the conditions provided by the RCCS preserve the original organizational architecture of the cells. The 3D conditions of the model enhanced differentiation in response to adipogenic, osteogenic, and chondrogenic inductive growth media. The immunophenotype and the immunocytochemistry showed generally high expression of CD90, CD44, and CD105, while CD146 expression was more restricted to ∼30% of cells. No expression was observed for CD31, CD34, and CD45 Ags. Two 3D tissue- and cell-based ex vivo models of the hDF supported the long-term maintenance of hDF-specific cell phenotypes and their ability to recapitulate typical cellular differentiation states. As such, these ex vivo models could be used to study the physiopathology of human odontogenesis. In addition, in a therapeutic context, they could be used to examine the role of specific chemical signals (e.g., new therapeutic agents) in the processes of dental tissue repair and regeneration
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
RCCSTM bioreactor-based modelled microgravity induces significant changes on in vitro 3D neuroglial cell cultures
Full text linkWe propose a human-derived neuro-/glial cell three-dimensional in vitro model to investigate the effects of microgravity on cell-cell interactions. A rotary cell-culture system (RCCS) bioreactor was used to generate a modelled microgravity environment, and morphofunctional features of glial-like GL15 and neuronal-like SH-SY5Y cells in three-dimensional individual cultures (monotypic aggregates) and cocultures (heterotypic aggregates) were analysed. Cell survival was maintained within all cell aggregates over 2 weeks of culture. Moreover, compared to cells as traditional static monolayers, cell aggregates cultured under modelled microgravity showed increased expression of specific differentiation markers (e.g., GL15 cells: GFAP, S100B; SH-SY5Y cells: GAP43) and modulation of functional cell-cell interactions (e.g., N-CAM and Cx43 expression and localisation). In conclusion, this culture model opens a wide range of specific investigations at the molecular, biochemical, and morphological levels, and it represents an important tool for in vitro studies into dynamic interactions and responses of nervous system cell components to microgravity environmental conditions
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