1,720,972 research outputs found
Exercise-induced recurrent myoglobinuria: Defective activity of inner carnitine palmitoyltransferase in muscle mitochondria of two patients
No full textIn carnitine palmitoyltransferase (CPT) deficiency, it is not known whether the outer (CPT-I) and the inner (CPT-II) mitochondrial activities are equally altered. By two different assays, we found that CPT activity in fresh intact mitochondria of two patients was normal or increased, indicating an active outer CPT. In controls and in one of the two patients, the isotope-exchange assay was also evaluated after disruption of mitochondria by sonication: in controls the activity almost doubled because of the contribution of inner CPT to the assay, but in the patients it did not increase, indicating absence of the CPT-II activity. After further disruption of mitochondria by freezing and all-glass homogenization, CPT activity in patients decreased to 36% and 10% of control. These data suggest that CPT deficiency was limited to the inner mitochondrial activity. The alteration could be explained by mutation of the membrane factor that determines in situ differences between CPT-I and II. © 1987 American Academy of Neurology
Clinical varieties of carnitine and carnitine palmitoyltransferase deficiency
No full textSeveral clinical entities are associated with disorders of fatty acid oxidation or transfer across the inner mitochondrial membrane. Over 40 cases of the primary carnitine deficiency syndrome have been reported to date and various subtypes have been characterized. This represents a large clinical spectrum. The deficiency of carnitine in muscle is at the basis of a syndrome characterized by muscle weakness and lipid storage myopathy. The systemic form of carnitine deficiency is more generalized and includes recurrent episodes of hepatic encephalopathy as well as lipid storage in muscle, liver and heart. In one subtype, hypoglycemia upon fasting and cardiomyopathy are found. There are also several causes of secondary carnitine deficiency states which are either acquired or associated with inborn errors of metabolism (organic acidurias, defects of acyl-CoA dehydrogenases). Clinically, Carnitine palmitoyltransferase (CPT) deficiency is a rather homogeneous syndrome presenting with recurrent episodes of myoglobinuria provoked by fasting or prolonged exercise. The only exception is an infantile variety associated with severe hypoglycemia and hepatic CPT deficiency. Using malonyl-CoA, a specific inhibitor of CPT-I, we had suggestions in five adult patients with myoglobinuria that CPT-II is lacking in muscle, liver and platelets while CPT-I is above the control level. The enzyme abnormality seems partial and limited to CPT-II or to its binding to the inner mitochondrial membrane. © 1987 The Canadian Society of Clinical Chemists
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
The expression of human mitochondrial ferritin rescues respiratory function in frataxin-deficient yeast.
No full textMyoglobinuria and carnitine palmityltransferase (CPT) deficiency: Studies with malonyl-CoA suggest absence of only CPT-II
No full textA 23-year-old man suffered since adolescence from recurrent myoglobinuria. His ketone body production during fasting was normal. Muscle, liver, and platelet carnitine palmityltransferase (CPT) ranged from 4 to 27% of control by isotope exchange and backward assays. Forward CPT activity was 34% of control in liver, whereas in muscle and platelets it was either normal or absent depending on the experimental conditions. CPT residual activity was studied with malonyl-CoA, a physiologic inhibitor of CPT-I (sensitive fraction) in rat liver mitochondria. In our patient, the insensitive fraction was missing in muscle, liver, and platelets, while the sensitive fraction was increased considerably in the same tissues. Similar results were obtained in platelets of two other patients with CPT deficiency. Increased malonyl-CoA sensitive CPT and decreased mal-onyl-CoA insensitive CPT suggest absence of only the CPT-II isoenzyme in these patients. © 1983 American Academy of Neurology
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
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