1,721,155 research outputs found
Amyloid fil rouge from invertebrate up to human ageing: A focus on Alzheimer disease
No full textAmyloid fibrils and fibril-like structures are currently estimated to represent many different products of several genes in humans and play a key role in many types of proteinopathies, commonly associated with ageing process. They share the mutual feature of aggregation-prone proteins and the building up of molecular-supramolecular structure, such as inter-neuronal plaques in the brain of Alzheimer's Disease (AD) patients, characterized by an extraordinary strength. Noteworthy, this type of structure has been reported in different organisms, in particular in invertebrates. The aim of the current review is to focus on alpha and beta amyloids i.e., SAAs, SAP and APP, elucidating the structure and function of amyloid proteins in invertebrates (such as nematods, annelids, molluscs, insects, ascidians) and highlighting their striking pattern of functional conservation when compared to human amyloid-like fibrils, thus focusing on possible new studies and applications for innovative therapies, particularly for AD, the most common and worldwide type of dementia
An evaluation of genotoxicity in human neuronal-type cells subjected to oxidative stress under an extremely low frequency pulsed magnetic field.
No full textThe possible genotoxicity of extremely low frequency magnetic field (ELF-MF) exposure is still a controversial topic. The most of the reported data suggests that it alone does not affect DNA integrity, but several recent reports have suggested that sinusoidal ELF-MF may increase the effect of known genotoxic agents. Only a few studies deal with non sinusoidal ELF-MF, including pulsed magnetic field (PMF), which are produced by several devices. The aim of this study is to investigate whether PMF exposure can interfere with DNA damage and repair in the presence of a genotoxic oxidative agent in neuronal type cells. To this purpose gamma-H2AX foci formation, which is a sensitive marker of DNA double strand breaks (DSB), was investigated at different points of time (1, 24, 48, 72. h) after the H2O2 treatment (300. μM for 1. h) under PMF exposure (1. mT, 50. Hz) in human neuroblastoma BE(2)C cells. Moreover, cytotoxicity evaluation, by MTT assay and cell cycle analysis, was performed at various points of time after the treatment. Taken together, results suggest that PMF exposure does not interfere with genotoxicity and cytotoxicity induced by oxidative stress
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
Gut microbiota changes in the extreme decades of human life: a focus on centenarians
No full textThe gut microbiota (GM) is a complex, evolutionarily molded ecological system, which contributes to a variety of physiological functions. The GM is highly dynamic, being sensitive to environmental stimuli, and its composition changes over the host's entire lifespan. However, the basic question of how much these changes may be ascribed to variables such as population, diet, genetics and gender, and/or to the aging process per se is still largely unanswered. We argue that comparison among studies on centenarians-the best model of healthy aging and longevity-recruited from different geographical areas/populations (different genetics and dietary habits) can help to disentangle the contribution of aging and non-aging-related variables to GM remodeling with age. The current review focuses on the role of population, gender and host genetics as possible drivers of GM modification along the human aging process. The feedback impact of age-associated GM variation on the GM-brain axis and GM metabolomics is also discussed. We likewise address the role of GM in neurodegenerative diseases such as Parkinson's and Alzheimer's, and its possible therapeutic use, taking advantage of the fact that centenarians are characterized by an extreme (healthy) phenotype versus patients suffering from age-related pathologies. Finally, it is argued that longitudinal studies combining metagenomics sequencing and in-depth phylogenetic analysis with a comprehensive phenotypic characterization of centenarians and patients using up-to-date omics (metabolomics, transcriptomics and meta-transcriptomics) are urgently needed
Present and future of anti-ageing epigenetic diets
No full textThe rapid technological advancements achieved in the last years have boosted the progressive identification of age-associated epigenetic changes. These studies not only contribute to shed light on the molecular basis of ageing and age-related diseases but, given the plasticity of epigenetic modifications, also provide the basis for anti-ageing interventions to counteract the onset of age-related diseases. In this review we will discuss nutritional interventions as a promising approach that can positively counteract epigenetic changes associated with ageing and promote the health for the elderly. First, we will give an overview of age-associated epigenetic signatures, focusing on DNA methylation. Then, we will report recent evidences regarding the epigenetic changes induced by nutritional interventions in the adulthood (referred as "epigenetic diets"), such as (i) caloric/dietary restriction, (ii) diet supplementation with nutrients involved in one-carbon metabolism and (iii) diet supplementation with bioactive food components. Attention will be drawn on the limits of current studies and the need of proper human models, such as those provided by the ongoing European project NU-AGE. Finally, we will discuss the potential impact of epigenetic diets on inflammaging and age-related diseases, focusing on cardiovascular disease, highlighting the involvement of epigenetic modifications other than DNA methylation, such as microRNA
Genes of human longevity: an endless quest?
No full textHuman longevity is a complex trait in which genetics, epigenetics, environmental and stochasticity differently contribute. To disentangle the complexity, our studies on genetics of longevity were, at the beginning, mainly focused on the extreme phenotypes, i.e. centenarians who escaped the major age-related diseases compared with cross sectional cohorts. Recently, we implemented this model by studying centenarians' offspring and offspring of non-long lived parents. In association, during studies on many candidate genes SNPs, positively or negatively correlated with longevity have been identified. The results obtained on Insulin-like Growth Factor 1 Receptor (IGF1R) polymorphisms showed a correlation between specific genetic variants combinations and the low plasma level of IGF1 in centenarians, suggesting an impact of the IGF-I/insulin pathway on human longevity. This pathway together with mammalian target of rapamycin (mTOR) will be reviewed as being the most promising for longevity. Further, we will summarise the role of apolipoprotein E (APOE) variants in human longevity since the results of the large European project GEHA (Genetics of Healthy Aging) indicate APOE among the chromosomal loci associated with longevity. On the other hand, the identification of longevity-related genes does not explain the mechanisms of healthy aging and longevity rather pose questions on epigenetic contribution, gene regulation and the interactions with essential genomes, i.e. mitochondrial DNA and microbiota. To fully disentangle what appears to be an endless quest, all the components of the complexity of human longevity genetics are taken into account
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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