1,720,988 research outputs found
Heterogeneity of retinal manifestations in mitochondrial myopathy: genotype/phenotype correlation in our experience.
No full textMitochondria, oxidative stress and neurodegeneration.
No full textMitochondria are involved in ATP supply to cells through oxidative phosphorylation (OXPHOS), synthesis of key molecules and response to oxidative stress, as well as in apoptosis. They contain many redox enzymes and naturally occurring inefficiencies of oxidative phosphorylation generate reactive oxygen species (ROS). CNS functions depend heavily on efficient mitochondrial function, since brain tissue has a high energy demand. Mutations in mitochondrial DNA (mtDNA), generation and presence of ROS and environmental factors may contribute to energy failure and lead to neurodegenerative diseases. Many rare metabolic disorders have been associated with mitochondrial dysfunction. More than 300 pathogenic mtDNA mutations involve proteins that regulate OXPHOS and mitochondrial structural integrity, and have also been described in neurodegenerative diseases with autosomal inheritance. Mitochondria may have an important role in ageing-related neurodegenerative disorders like Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). In primary mitochondrial and neurodegenerative disorders, there is strong evidence that mitochondrial dysfunction occurs early and has a primary role in pathogenesis. In the present review, we discuss several mitochondrial diseases as models of neurodegeneration
A case of 3243A>G mutation in mtDNA presenting as apparently idiopathic hyperCKemia.
No full textThe 3243A>G mutation of mtDNA usually is associated with MELAS syndrome. Here we report a patient with the 3243A>G mutation presenting only recurrent muscle fatigue and elevated levels of serum creatine kinase (CK). The mother of the proband was referred to us for type 2 diabetes mellitus, muscle pain and sensorineural hearing loss. The percentage of mutation load in different tissues was similar in both subjects, except in the urinary epithelium. The mutation load in the son's urinary epithelial cells (UEC) was consistently higher (nearly 50%) than in his muscle (nearly 20%). We conclude that a correlation between the proportion of the UEC mutation load and the severity of the disease was lacking in this pedigree. The use of UEC as the tissue of choice in the noninvasive diagnosis of the 3243A>G mutation offers a very attractive alternative to muscle biopsy. Finally, our data expand the clinical spectrum of the 3243A>G mutation
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
Sporadic myopathy, myoclonus, leukoencephalopathy, neurosensory deafness, hypertrophic cardiomyopathy and insulin resistance associated with the mitochondrial 8306 T>C MTTK mutation.
No full textWe report a new T8306C transition in the D-stem of the MTTK gene of a 67-year-old man who manifested severe adult onset myopathy, myoclonus, leukoencephalopathy, neurosensory hypoacusis, hypertrophic cardiomyopathy and insulin resistance. No other family member was affected, suggesting that our patient was a sporadic case. The T8306C mutation was heteroplasmic in several tissues of the proband, while it was absent from his asymptomatic siblings. Single fibre analysis confirmed the segregation of higher mutational load in cytochrome c oxidase-deficient fibres. The mutation T8306C is predicted to disrupt a highly conserved base pair and was not found in more than 120 controls. This finding broadens the phenotypic and molecular spectrum of mitochondrial tRNA(Lys) associated disorders
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