1,720,976 research outputs found
DISPOSITIVO PER IL PRELIEVO E L'ANALISI DI UN FLUIDO BIOLOGICO
No full textDispositivo per il prelievo e l’analisi di un fluido biologico in micro-volumi; il dispositivo comprende un sensore, il quale è configurato per rilevare e/o quantificare un analita presente nel campione e/o una proprietà del campione.
Il dispositivo comprende, inoltre, un sistema di trasporto, il quale è configurato per il trasporto del campione dall’ambiente esterno (in particolare, da un essere vivente) al sensore e comprende un materiale fibroso, configurato per permettere la diffusione del fluido biologico attraverso sé stesso e presentante una porzione di analisi disposta in corrispondenza del sensore ed una porzione di trasporto dotata di una prima estremità che si aggetta all’esterno del dispositivo ed una seconda estremità in contatto con la porzione di analisi
Fast data fitting scheme for compressive multispectral fluorescence lifetime imaging
No full textA single-pixel camera combined with compressive sensing techniques is a promising fluorescence microscope scheme for acquiring a multidimensional dataset (space, spectrum, and lifetime) and for reducing the measurement time with respect to conventional microscope schemes. However, upon completing the acquisition, a computational step is necessary for image reconstruction and data analysis, which can be time-consuming, potentially canceling out the beneficial effect of compressive sensing. In this work, we propose and experimentally validate a fast-fit workflow based on global analysis and multiple linear fits, which significantly reduces the computation time from tens of minutes to less than 1 s. Moreover, as the method is interlaced with the measurement flow, it can be applied in parallel with the acquisitions
Optical Pacing of Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes Mediated by a Conjugated Polymer Interface
No full textThe use of light for triggering skeletal and cardiac muscles allows lower invasiveness higher selectivity and unprecedented possibility to target individual cells or even subcellular compartments in a temporally and spatially precise manner. Because cells are in general transparent, this requires the development of suitable interfaces that bestow light sensitivity to living matter. In the present work, successfully demonstrated is the use of conjugated polymer films as transducer to optically enhance the contraction rate of a human and patient-specific cardiac in vitro cell model. By different experimental approaches, the coupling mechanism to the photothermal effect is assigned. This work extends the range of application of the polymer-mediated cell photostimulation phenomenon to cardiac muscle cells, opening up possible applications in cardiac therapy and for implementation of in vitro studies
Modulation of Mechanosensitive Potassium Channels by a Membrane-targeted Nongenetic Photoswitch
Full text linkMechanosensitive ion channels are present in the plasma membranes of all cells. They play a fundamental role in converting mechanical stimuli into biochemical signals and are involved in several physiological processes such as touch sensation, hearing, and blood pressure regulation. This protein family includes TWIK-related arachidonic acid-stimulated K+ channel (TRAAK), which is specifically implicated in the maintenance of the resting membrane potential and in the regulation of a variety of important neurobiological functions. Dysregulation of these channels has been linked to various diseases, including blindness, epilepsy, cardiac arrhythmia, and chronic pain. For these reasons, mechanosensitive channels are targets for the treatment of several diseases. Here, we propose a new approach to investigate TRAAK ion channel modulation that is based on nongenetic photostimulation. We employed an amphiphilic azobenzene, named Ziapin2. In the dark, Ziapin2 preferentially dwells in the plasma membrane, causing a thinning of the membrane. Upon light irradiation, an isomerization occurs, breaking the dimers and inducing membrane relaxation. To study the effect of Ziapin2 on the mechanosensitive channels, we expressed human TRAAK (hTRAAK) channels in HEK293T cells. We observed that Ziapin2 insertion in the membrane is able per se to recruit hTRAAK, permitting the exit of K+ ions outside the cells with a consequent hyperpolarization of the cell membrane. During light stimulation, membrane relaxation induces hTRAAK closure, generating a consistent and compensatory depolarization. These results add information to the Ziapin2 mechanism and suggest that membrane deformation can be a tool for the nonselective modulation of mechanosensitive channels
Skeletal muscle cells opto-stimulation by intramembrane molecular transducers
Full text linkOptical stimulation and control of muscle cell contraction opens up a number of interesting applications in hybrid robotic and medicine. Here we show that recently designed molecular phototransducer can be used to stimulate C2C12 skeletal muscle cells, properly grown to exhibit collective behaviour. C2C12 is a skeletal muscle cell line that does not require animal sacrifice Furthermore, it is an ideal cell model for evaluating the phototransducer pacing ability due to its negligible spontaneous activity. We study the stimulation process and analyse the distribution of responses in multinuclear cells, in particular looking at the consistency between stimulus and contraction. Contractions are detected by using an imaging software for object recognition. We find a deterministic response to light stimuli, yet with a certain distribution of erratic behaviour that is quantified and correlated to light intensity or stimulation frequency. Finally, we compare our optical stimulation with electrical stimulation showing advantages of the optical approach, like the reduced cell stress.A study on the stimulation of cells with light, thanks to a photochromic molecule, called Ziapin2. It shows the difference between the light stimulation and the electrical stimulation in terms of cell viability and performance
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
Photocell-Based Optofluidic Device for Clogging-Free Cell Transit Time Measurements
Full text linkMeasuring the transit time of a cell forced through a bottleneck is one of the most widely used techniques for the study of cell deformability in flow. It in turn provides an accessible and rapid way of obtaining crucial information regarding cell physiology. Many techniques are currently being investigated to reliably retrieve this time, but their translation to diagnostic-oriented devices is often hampered by their complexity, lack of robustness, and the bulky external equipment required. Herein, we demonstrate the benefits of coupling microfluidics with an optical method, like photocells, to measure the transit time. We exploit the femtosecond laser irradiation followed by chemical etching (FLICE) fabrication technique to build a monolithic 3D device capable of detecting cells flowing through a 3D non-deformable constriction which is fully buried in a fused silica substrate. We validated our chip by measuring the transit times of pristine breast cancer cells (MCF-7) and MCF-7 cells treated with Latrunculin A, a drug typically used to increase their deformability. A difference in transit times can be assessed without the need for complex external instrumentation and/or demanding computational efforts. The high throughput (4000–10,000 cells/min), ease of use, and clogging-free operation of our device bring this approach much closer to real scenarios
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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