1,720,972 research outputs found
L-deprenyl as an inhibitor of menadione-induced permeability transition in liver mitochondria
No full textElectrophysiology clarifies the megariddles of the permeability transition pore
No full textAfter a brief review of the early history of mitochondrial electrophysiology, the contribution of this approach to the study of the mitochondrial permeability transition (MPT) is recapitulated. It has for example provided evidence for a dimeric nature of the MPT pore, allowed the distinction between two levels of control of its activity, and underscored the relevance of redox events for the phenomenon. Single-channel recording provides a means to finally solve the riddle of the biochemical entity underlying it by comparing the characteristics of the pore with those of channels formed by candidate molecules or complexes. The possibility that this entity may be the protein import machinery of the inner mitochondrial membrane is emphasized. (C) 2010 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved
Mitochondrial permeability transitions: how many doors to the house?
Full text linkThe inner mitochondrial membrane is famously impermeable to solutes not provided with a specific carrier. When this impermeability is lost, either in a developmental context or under stress, the consequences for the cell can be far-reaching. Permeabilization of isolated mitochondria, studied since the early days of the field, is often discussed as if it were a biochemically well-defined phenomenon, occurring by a unique mechanism. On the contrary, evidence has been accumulating that it may be the common outcome of several distinct processes, involving different proteins or protein complexes, depending on circumstances. A clear definition of this putative variety is a prerequisite for an understanding of mitochondrial permeabilization within cells, of its roles in the life of organisms, and of the possibilities for pharmacological intervention
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
Novel channels of the inner mitochondrial membrane
No full textAlong with a large number of carriers, exchangers and "pumps", the inner mitochondrial membrane contains ion-conducting channels which endow it with controlled permeability to small ions. Some have been shown to be the mitochondrial counterpart of channels present also in other cellular membranes. The manuscript summarizes the current state of knowledge on the major inner mitochondrial membrane channels. properties, identity and proposed functions. Considerable attention is currently being devoted to two K(+)-selective channels, mtK(ATP) and mtBK(Ca). Their activation in "preconditioning" is considered by many to underlie the protection of myocytes and other cells against subsequent ischemic damage. We have recently shown that in apoptotic lymphocytes inner membrane mtK(v)1.3 interacts with the pro-apoptotic protein Bax after the latter has inserted into the outer mitochondrial membrane. Whether the just-discovered mtIK(Ca) has similar cellular role(s) remains to be seen. The Ca(2+) "uniporter" has been characterized electrophysiologically, but still awaits a molecular identity. Chloride-selective channels are represented by the 107 pS channel, the first mitochondrial channel to be observed by patch-clamp, and by a similar to 400 pS pore we have recently been able to fully characterize in the inner membrane of mitochondria isolated from a colon turnout cell line. This we propose to represent a component of the Permeability Transition Pore. The available data exclude the previous tentative identification with porin, and indicate that it coincides instead with the still molecularly unidentified "maxi" chloride channel. (C) 2008 Elsevier B.V. All rights reserved
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
Intermediate conductance Ca2+-activated potassium channel (K(Ca)3.1) in the inner mitochondrial membrane of human colon cancer cells
No full textPatch-clamping mitoplasts isolated from human colon carcinoma 116 cells has allowed the identification and characterization of the intermediate conductance Ca(2+)-activated K(+)-selective channel K(Ca)3.1, previously studied only in the plasma membrane of various cell types. Its identity has been established by its biophysical and pharmacological properties. Its localisation in the inner membrane of mitochondria is indicated by Western blots of subcellular fractions, by recording of its activity in mitochondria made fluorescent by a mitochondria-targeted fluorescent protein and by the co-presence of channels considered to be markers of the inner membrane. Moderate increases of mitochondrial matrix [Ca(2+)] will cause mtK(Ca)3.1 opening, thus linking inner membrane K(+) permeability and transmembrane potential to Ca(2+) signalling. (C) 2009 Elsevier Ltd. All rights reserved
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