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Transcription and translation of deleted mitochondrial genomes in Kearns-Sayre syndrome: implications for pathogenesis.
No full textLarge-scale deletions of human mitochondrial DNA (mtDNA) have been described in a clinical subgroup of mitochondrial encephalomyopathies associated with progressive external ophthalmoplegia and ragged-red fibers in skeletal muscle, including cases of Kearns-Sayre syndrome (KSS). Since the decrease in the activities of mtDNA-encoded respiratory-chain enzymes did not seem to be correlated to the sites of the deletions, the role played by the mtDNA deletions in the pathogenesis of these disorders has been unclear. To address this issue, we studied transcription and translation of deleted mtDNA in two patients with KSS harboring two different deletions. We found that the deleted genomes were transcriptionally active in both cases. Analysis of translation in one of the patients showed that the "fusion" mRNA derived from the region spanning the deletion did not seem to be translated. Thus, the biochemical defects in KSS can be explained by a lack of translation of mtDNA-encoded respiratory-chain polypeptides in some mitochondria, which, in turn, is probably due to the lack of indispensable mtDNA-encoded tRNAs in these organelles. These results imply that deleted mtDNAs may be segregated from normal genomes in this group of diseases. It seems likely that the absence of translation in proliferating mitochondria containing partially deleted genomes plays a major role in the pathogenesis of these disorders
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
Task force guidelines handbook: EFNS guidelines on diagnosis and management of fatty acid mitochondrial disorders
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PGC-1alpha/beta induced expression partially compensates for respiratory chain defects in cells from patients with mitochondrial disorders.
No full textMembers of the peroxisome proliferator-activated receptor gamma coactivator (PGC) family are potent inducers of mitochondrial biogenesis. We have tested the potential effect of increased mitochondrial biogenesis in cells derived from patients harboring oxidative phosphorylation defects due to either nuclear or mitochondrial DNA mutations. We found that the PGC-1 alpha and/or PGC-1 beta expression improved mitochondrial respiration in cells harboring a complex III or IV deficiency as well as in transmitochondrial cybrids harboring mitochondrial encephalomyopathy lactic acidosis and stroke A3243G tRNA((Leu)UUR) gene mutation. The respiratory function improvement was found to be associated with increased levels of mitochondrial components per cell, although this increase was not homogeneous. These results reinforce the concept that increased mitochondrial biogenesis is a promising venue for the treatment of mitochondrial diseases
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
Task force guidelines handbook: EFNS guidelines on diagnosis and management of fatty acid mitochondrial disorders
No full textGuidelines in the diagnosis and current dietary treatment of long-chain fatty acid (LCFA) defects have been collected according to evidence-based medicine. Since the identification of carnitine and carnitine palmitoyltransferase deficiency more than 25 years ago, nearly every enzymatic step required for beta-oxidation has been associated with an inherited metabolic disorder. These disorders effectively preclude the use of body fat as an energy source. Clinical consequences can range from no symptoms to severe manifestations including cardiomyopathy, hypoglycaemia, peripheral neuropathy and sudden death. A diet high in carbohydrates, diet with medium-chain triglycerides and reduced amount of LCFA has a beneficial effect (class IV evidence) and in appropriate deficiency states carnitine and riboflavin are used (good practice points)
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