1,720,998 research outputs found
Magnesium: Biochemistry, nutrition, detection, and social impact of diseases linked to its deficiency
Full text linkMagnesium plays an important role in many physiological functions. Habitually low intakes of magnesium and in general the deficiency of this micronutrient induce changes in biochemical pathways that can increase the risk of illness and, in particular, chronic degenerative diseases. The assessment of magnesium status is consequently of great importance, however, its evaluation is difficult. The measurement of serum magnesium concentration is the most commonly used and readily available method for assessing magnesium status, even if serum levels have no reliable correlation with total body magnesium levels or concentrations in specific tissues. Therefore, this review offers an overview of recent insights into magnesium from multiple perspectives. Starting from a biochemical point of view, it aims at highlighting the risk due to insufficient uptake (frequently due to the low content of magnesium in the modern western diet), at suggesting strategies to reach the recommended dietary reference values, and at focusing on the importance of detecting physiological or pathological levels of magnesium in various body districts, in order to counteract the social impact of diseases linked to magnesium deficiency
The assessment of intracellular magnesium: Different strategies to answer different questions
No full textThe role of magnesium in cell metabolism is complex and still not completely clarified. Although magnesium has been shown to modulate many phenomena in cells, its intracellular distribution and subcellular compartmentalization have not yet elucidated in detail, mainly as a consequence of the inadequacy of analytical techniques. The method usually employed to quantify total magnesium in cells or tissue are F-AAS or more sensitive techniques as graphite furnace AAS and inductively coupled plasma mass spectroscopy (MS). Thanks to the development of new specific fluorescent dyes, several progresses have been made in the comprehension of the fundamental biological process at the cellular and sub-cellular level. Moreover, the biological function of a chemical element in cells does not only require the determination of its intracellular quantity but also the spatial distribution of its concentration. Most of Mg2+-sensitive fluorescent dyes detect only the free metal ions, precluding the possibility of identifying the total pool of Mg. This review aims at giving an overview on different techniques focusing on two approaches to quantify total Mg in a small cell population or in single cells: i) Indirect Mg detection, labelbased methods that represent the best choice to quantify the elemental concentration on a large cell population; ii) direct Mg detection (label-free), Synchrotron-based x-ray microscopy techniques that offer the possibility of achieving a detailed map of the intracellular concentration of a specific chemical element on single cell
Development and Characterization of Azithromycin-Loaded Microemulsions: A Promising Tool for the Treatment of Bacterial Skin Infections
Full text linkIn recent years, the treatment of bacterial skin infections has been considered a major healthcare issue due to the growing emergence of antibiotic-resistant strains of Staphylococcus aureus. The incorporation of antibiotics in appropriate nanosystems could represent a promising strategy, able to overcome several drawbacks of the topical treatment of infections, including poor drug retention within the skin. The present work aims to develop microemulsions containing azithromycin (AZT), a broad-spectrum macrolide antibiotic. Firstly, AZT solubility in various oils, surfactants and co-surfactants was assessed to select the main components. Subsequently, microemulsions composed of vitamin E acetate, Labrasol (R) and Transcutol (R) P were prepared and characterized for their pH, viscosity, droplet size, zeta potential and ability to release the drug and to promote its retention inside porcine skin. Antimicrobial activity against S. aureus methicillin-resistant strains (MRSA) and the biocompatibility of microemulsions were evaluated. Microemulsions showed an acceptable pH and were characterized by different droplet sizes and viscosities depending on their composition. Interestingly, they provided a prolonged release of AZT and promoted its accumulation inside the skin. Finally, microemulsions retained AZT efficacy on MRSA and were not cytotoxic. Hence, the developed AZT-loaded microemulsions could be considered as useful nanocarriers for the treatment of antibiotic-resistant infections of the skin
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
Colorectal Cancer Cell Invasion and Functional Properties Depend on Peri-Tumoral Extracellular Matrix
Full text linkWe investigated how the extracellular matrix (ECM) affects LoVo colorectal cancer cells behavior during a spatiotemporal invasion. Epithelial-to-mesenchymal transition (EMT) markers, matrix-degrading enzymes, and morphological phenotypes expressed by LoVo-S (doxorubicin-sensitive) and higher aggressive LoVo-R (doxorubicin-resistant) were evaluated in cells cultured for 3 and 24 h on Millipore filters covered by Matrigel, mimicking the basement membrane, or type I Collagen reproducing a desmoplastic lamina propria. EMT and invasiveness were investigated with RT-qPCR, Western blot, and scanning electron microscopy. As time went by, most gene expressions decreased, but in type I Collagen samples, a strong reduction and high increase in MMP-2 expression in LoVo-S and -R cells occurred, respectively. These data were confirmed by the development of an epithelial morphological phenotype in LoVo-S and invading phenotypes with invadopodia in LoVo-R cells as well as by protein-level analysis. We suggest that the duration of culturing and type of substrate influence the morphological phenotype and aggressiveness of both these cell types differently. In particular, the type I collagen meshwork, consisting of large fibrils confining inter fibrillar micropores, affects the two cell types differently. It attenuates drug-sensitive LoVo-S cell aggressiveness but improves a proteolytic invasion in drug-resistant LoVo-R cells as time goes by. Experimental studies on CRC cells should examine the peri-tumoral ECM components, as well as the dynamic physical conditions of TME, which affect the behavior and aggressiveness of both drug-sensitive and drug-resistant LoVo cells differently
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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