1,721,088 research outputs found
Encephalomyopathies caused by abnormal nuclear-mitochondrial intergenomic cross-talk
No full textAutosomal dominant Progressive External Ophthalmoplegias are Mendelian disorders characterized by the accumulation of multiple deletions of mitochondrial DNA in critical tissues. Most of the Autosomal dominant Progressive External Ophthalmoplegias families carry heterozygous mutations in one of three genes: ANT1, encoding the muscle-heart specific mitochondrial adenine nucleotide translocator, Twinkle, encoding the mitochondrial DNA helicase, and POLG1, encoding the catalytic subunit of the mitochondrial DNA-specific polymerase. Mutations in both POLG1 alleles are also found in autosomal recessive Progressive External Ophthalmoplegias sibships with multiple affected members and in apparently sporadic cases. In addition, recessive POLG1 mutations are responsible for three additional diseases: Alpers-Huttenlocher hepatopathic poliodystrophy, Sensory-Ataxic Neuropathy Dysarthria and Ophthalmoplegia and juvenile SpinoCerebellar Ataxia-Epilepsy syndrome. Mitochondrial neuro-gastro-intestinal encephalomyopathy is an autosomal recessive disorder of juvenile onset, caused by mutations in the gene encoding Thymidine Phosphorylase. Thymidine Phosphorylase is involved in the control and maintenance of the pyrimidine nucleoside pool of the cell. Finally, mitochondrial DNA depletion syndrome is a heterogeneous group of disorders characterized by a reduction in mitochondrial DNA copy number. Clinically, they include a myopathic form, a more generalized encephalomyopathic form and a fatal infantile hepato-cerebral syndrome leading to rapidly progressive liver and brain failure. To date, eight genes have been associated with mitochondrial DNA depletion syndrome. Novel disease genes have recently been added to this list, including OPA1 and GFER, and new clinical variants add further complexity to this expanding area of mitochondrial medicine
Myoclonus epilepsy in mitochondrial disorders
No full textMitochondrial disorders is a group of clinical entities associated with abnormalities of the mitochondrial respiratory chain (MRC), which carries out the oxidative phosphorylation (OXPHOS) of ADP into ATP. As the MRC is the result of genetic complementation between two separate genomes, nuclear and mitochondrial, OXPHOS failure can derive from mutations in either nuclear-encoded, or mitochondrial-encoded, genes. Epilepsy is a relatively common feature of mitochondrial disease, especially in early-onset encephalopathies of infants and children. However, the two most common entities associated with epilepsy include MERRF, for Myoclonic Epilepsy with Ragged Red Fibers, and AHS, or Alpers-Huttenlocher syndrome, also known as hepatopathic poliodystrophy. Whilst MERRF is a maternally inherited condition caused by mtDNA mutations, particularly the 8344A>G substitution in the gene encoding mt-tRNALys, AHS is typically caused by recessive mutations in POLG, encoding the catalytic subunit of polymerase gamma, the only mtDNA polymerase in humans. AHS is the most severe, early-onset, invariably fatal syndrome within a disease spectrum, which also include other epileptogenic entities, all due to POLG mutations and including Spino-cerebellar Ataxia and Epilepsy (SCAE). This review reports the main clinical, neuroimaging, biochemical, and molecular features of epilepsy-related mitochondrial syndrome, particularly MERRF and AHS
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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 redundancy resolution method for an anthropomorphic dual-arm manipulator based on a musculoskeletal criterion
No full textIn order to make humans feeling comfortable when working with robots, it is necessary for robots to be as much as possible “human-like” in both their appearance and movements. In redundant manipulators, it is possible to use the additional degrees of freedom in order to make the robot motion more human-like, thus increasing the quality of the human-robot interaction. In this work, a redundancy resolution method to address this issue is presented. Such a method considers the human musculoskeletal system and a biomechanical model of the human upper limbs in order to define a strategy to solve the redundancy for a dual-arm anthropomorphic manipulator as a human would do, then making the robot able to both perform the prescribed task and to assume human-like postures
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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