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L'esercizio fisico e l'elettro-stimolazione, strategie per contrastare il declino muscolare negli anziani.
Full text linkAging is a multifactorial process characterized by a constant and relentless decline of the structure, functions and consequently of muscle performance.
One of the most obvious effects of aging in humans is the reduction of muscle mass, known as sarcopenia, which its development changes from individual to individual and which leads to reduced functional capacity (strength and resistance). Factors that contribute to the progress of this state are the decrease in both the number and size of myofibers and the amount of motoneurons that innervate the muscle fibers. Histological examinations carried out on the muscles of the elderly have demonstrated that denervation can contribute to atrophy and in addition the immobility and a life of sedentary accelerates the process, while the physical exercise protects in part from the effects of aging. Several studies have shown that regular exercise can prolong life expectancy and slow the effects of aging. At the molecular level calcium, and consequently the sarcoplasmic reticulum, plays a vital role in metabolic processes and structural adaptation of muscle through the activation of specific signaling pathways, in response to the type of stimulus received. This thesis focuses precisely on the benefits of physical exercise and whether these can be compared to those obtained by using a training protocol induced by electrostimulation. This could be useful in rehabilitation as exercise, especially in the elderly, it is not always applicable due to pathological and psychological problems.
To determine the effects of aging and to correlate them with different lifestyles were studied the vastus lateralis muscle of three distinct groups of people (a) healthy sedentary seniors (b) healthy seniors with at least 30 years of regular exercise (c) young athletes. In these subjects muscle was characterized in relation to age and type of exercise to determine the effects of the voluntary exercise on the progress of sarcopenia during aging. From the data obtained through a series of functional tests was showed that the physically active seniors have characteristics most similar to young compared to the sedentary group of the same age. This is evidence of the fact that physically active seniors are a very powerful and performing group and it's possible to compare them to master athletes of the same age. Morphological analysis and histological studies have shown that the sedentary seniors present more denervated fibers than the other two groups, and that the physically active seniors have a significantly higher percentage of slow fibers, which, however, does not depend by the type of exercise done. Also it was detected in all three groups fibers that coexpress both myosin fast and slow and specifically the group of the sedentary seniors presents an higher percentage of coexpressing fibers than the other two groups. However, the serial sections of sedentary seniors showed the presence of coexpressing fibers of small dimensions and angled (denervated); therefore, this fact suggests that these fibers are slow fibers that coexpress fast myosin isoforms through default myogenic programs. On the contrary, the coexpressing muscle fibers in the physically active seniors are similar in size to the innervated "pure" muscle fibers, only fast or only slow. Based on the results obtained high levels of exercise appear to have beneficial effects on reinnervation of muscle fibers, resulting in conservation of muscle function, size and structure, thus delaying the functional decline and loss of independence which are common in older people.
However, some pathological conditions and also some psychological situations, typical of the elderly, limit the ability to perform physical activity. It is therefore necessary to find an alternative to physical exercise that can maintain the beneficial properties, and above all that can be safe; these features can all be found in electrostimulation (ES). To determine whether this type of therapy can be effective in the elderly was also developed a study to define the effects of ES on aged human muscle, compared with a group of seniors the performed a voluntary strength training program (Leg Press, LP), for a period of nine weeks. In both groups of seniors, after the two workouts, it was noted an improvement in functional parameters, but only those who received the ES treatment presented an increase in the maximum isometric strength of the muscles vastus lateralis. Electrostimulation, unlike the LP, has kept unchanged the overall average size of the fibers, while there was an increment of the diameter and the number of fast fibers and a decrement of both parameters in slow type fibers. Of note, no sign of fibrosis and/or infiltration of inflammatory cells was detected in the treated muscles for both types of training. In addition, analysis of ultrastructure not viewed any alteration of muscle structure before and after treatment.
After both treatments of ES and LP was recorded an activation of both the pathway of calcineurin/NFAT and calcium calmodulin dependent kinase (CaMKII), both key points for muscle remodeling. The quantitative evaluation of all the proteins that constitute the sarcoplasmic reticulum, shows a significant increment in protein levels of SERCA2 and Sarcalumenin and a decrement CASQ1 after ES, while after LP there were no significant changes. Analysis of quantitative PCR (qPCR) were made in order to clarify whether the level of Sarcalumenin SERCA2 and CASQ RNA are regulated by electrostimulation. None of the genes is up-regulated or down-regulated in a statistically significant way by the ES training, suggesting a regulation at the post transcriptional level. The vastus lateralis muscle is a mixture of different types of muscle fibers, consequently, the increase in the average quantity of SERCA2 and Sarcalumenin in total homogenates can be attributed to all the fibers or to a specific subpopulation (ie, slow twitch fibers or intermediate oxidative fibers IIA). To see if the increase in SERCA2 is against fast fibers in muscles treated by electrostimulation, it was developed a protocol immunofluorescence to assess the co-expression of myosin fast and SERCA2. After the ES the number of mixed fiber SERCA2/fast myosin is significantly increased, but was unchanged after LP. From the analysis of the intensity of fluorescence of fast myosin it was found that certain fast-twitch fibers exhibit a lower signal of fast myosin respectively in sections post ES and post LP and about 50% of such fibers were also positive SERCA2. From these observations we conclude that the mixed fibers for fast myosin/SERCA2 are a heterogeneous population and a part of these fibers probably expresses both isoforms of myosin.
In conclusion, in this thesis were developed experimental protocols that have allowed to identify some favorable changes induced by physical exercise in the seniors. Moreover, thanks to the stabilization of the nuclear translocation of NFATc1 that remains even after several days last training session, it can be assign to the role of biomarker of inactivity (NFATc1 cytoplasmic) and activation "muscle" (myonuclear translocation), whether induced from ES or LP . Also for the first time it was shown that the ES is able to neuro-modulate with beneficial effects for the quality of the muscle, the mobility and the functional performances of the seniors. Thus the ES may be a viable approach to counter the problems and the atrophy of the muscle caused by the aging process both for healthy seniors and subjects to chronic health conditions, having as ultimate goal to improve lifestyle
Calsequestrins in skeletal and cardiac muscle from adult Danio rerio
Full text linkCalsequestrin (Casq) is a high capacity, low affinity Ca2+-binding protein, critical for Ca2+-buffering in cardiac and skeletal muscle sarcoplasmic reticulum. All vertebrates have multiple genes encoding for different Casq isoforms. Increasing interest has been focused on mammalian and human Casq genes since mutations of both cardiac (Casq2) and skeletal muscle (Casq1) isoforms cause different, and sometime severe, human pathologies. Danio rerio (zebrafish) is a powerful model for studying function and mutations of human proteins. In this work, expression, biochemical properties cellular and sub-cellular localization of D. rerio native Casq isoforms are investigated. By quantitative PCR, three mRNAs were detected in skeletal muscle and heart with different abundances. Three zebrafish Casqs: Casq1a, Casq1b and Casq2 were identified by mass spectrometry (Data are available via ProteomeXchange with identifier PXD002455). Skeletal and cardiac zebrafish calsequestrins share properties with mammalian Casq1 and Casq2. Skeletal Casqs were found primarily, but not exclusively, at the sarcomere Z-line level where terminal cisternae of sarcoplasmic reticulum are located
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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