14 results match your criteria: "INSERM EMI 9929 & université Bordeaux-2[Affiliation]"
C R Biol
May 2003
INSERM EMI 9929 & université Bordeaux-2, 146, rue Léo-Saignat, 33076 Bordeaux, France.
The enzymatic activities of threonine pathway in Escherichia coli are sensitive to pollutants such as cadmium, copper and mercury, which, even at low concentration, can substantially decrease or even block the pathway at several steps. Our aim was to investigate the complex effects on a metabolic pathway of such general enzyme inhibitors with several sites of action, using a previously developed computer simulation of the pathway. For this purpose, the inhibition parameters were experimentally determined and incorporated in the model.
View Article and Find Full Text PDFBiochem J
March 2003
INSERM-EMI 9929, Physiologie mitochondriale, Université Victor Segalen-Bordeaux 2, 146 rue Léo-Saignat, F-33076 Bordeaux-cedex, France.
The study of mitochondrial diseases has revealed dramatic variability in the phenotypic presentation of mitochondrial genetic defects. To attempt to understand this variability, different authors have studied energy metabolism in transmitochondrial cell lines carrying different proportions of various pathogenic mutations in their mitochondrial DNA. The same kinds of experiments have been performed on isolated mitochondria and on tissue biopsies taken from patients with mitochondrial diseases.
View Article and Find Full Text PDFAnesthesiology
December 2002
Laboratoire d'Anesthésiologie (INSERM EMI 9929), Université Victor Segalen Bordeaux 2, F-33076 Bordeaux Cedex, France.
Background: Adaptation to chronic exposure to hypoxia alters energy metabolism in the heart, particularly in the left ventricle, which undergoes a loss in oxidative capacity. Highly lipophilic local anesthetics interfere with mitochondrial energy metabolism. The purpose of this study was to compare the effects of bupivacaine on mitochondrial energy metabolism in heart of rats subjected to normoxic or hypoxic environments.
View Article and Find Full Text PDFMol Biol Rep
July 2003
Inserm EMI 9929, Université de Bordeaux 2, France.
Inside the eukaryotic cell, mitochondria are internal organelles of prokaryotic origin, responsible for energy supply in the cell. The control of the mitochondrial ATP production is a complex problem with different patterns according to different tissues and organs. Our aim is to continue to develop the modelling of oxidative phosphorylation in different tissues, to model other parts of mitochondrial metabolism and to include this virtual mitochondria in a virtual cell.
View Article and Find Full Text PDFBiochem J
August 2001
INSERM-EMI 9929, Université Victor Segalen Bordeaux 2, 146 rue Léo-Saignat, F-33076 Bordeaux Cedex, France.
Respiratory-chain-complex subunits in mitochondria are encoded by nuclear or mitochondrial DNA. This property might have profound implications for the phenotypic expression of mutations affecting oxidative phosphorylation complexes. The aim of this paper is to study the importance of the origin of the mutation (nuclear or mitochondrial) on the expression of mitochondrial defects.
View Article and Find Full Text PDFBiochem J
June 2001
INSERM EMI 9929, University Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France.
A computer simulation of the threonine-synthesis pathway in Escherichia coli Tir-8 has been developed based on our previous measurements of the kinetics of the pathway enzymes under near-physiological conditions. The model successfully simulates the main features of the time courses of threonine synthesis previously observed in a cell-free extract without alteration of the experimentally determined parameters, although improved quantitative fits can be obtained with small parameter adjustments. At the concentrations of enzymes, precursors and products present in cells, the model predicts a threonine-synthesis flux close to that required to support cell growth.
View Article and Find Full Text PDFBiochem J
June 2001
INSERM EMI 9929, University Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France.
We have developed an experimental model of the whole threonine pathway that allows us to study the production of threonine from aspartate under different conditions. The model consisted of a desalted crude extract of Escherichia coli to which we added the substrates and necessary cofactors of the pathway: aspartate, ATP and NADPH. In this experimental model we measured not only the production of threonine, but also the time dependence of all the intermediate metabolites and of the initial substrates, aspartate, ATP and NADPH.
View Article and Find Full Text PDFBiochem J
June 2001
INSERM EMI 9929, University Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France.
We have determined the kinetic parameters of the individual steps of the threonine pathway from aspartate in Escherichia coli under a single set of experimental conditions chosen to be physiologically relevant. Our aim was to summarize the kinetic behaviour of each enzyme in a single tractable equation that takes into account the effect of the products as competitive inhibitors of the substrates in the forward reaction and also, when appropriate (e.g.
View Article and Find Full Text PDFBiochim Biophys Acta
March 2001
INSERM EMI 9929, Université Bordeaux 2, 146 rue Léo-Saignat, F-33076 Bordeaux Cédex, France.
This paper shows how metabolic control analysis (MCA) can help to explain two important features of mitochondrial diseases: (i) the existence of a threshold in the expression of the complex deficiencies on the respiratory flux or on ATP synthesis, i.e. the fact that it is necessary to have a large complex deficiency in order to observe a substantial decrease in these fluxes; (ii) the tissue specificity, i.
View Article and Find Full Text PDFCell Calcium
February 2001
European Institute of Chemistry and Biology, & INSERM EMI-U.9929 Mitochondrial Physiology, Victor Segalen-Bordeaux 2 University, Bordeaux cedex, F-33076, France.
Kinetic fluorescence imaging and the potentiometric probe tetramethylrhodamine methyl ester (TMRM) were used to evoke and detect changes in membrane potential (delta Psi(m)) of individual mitochondria in living cells. As a combined effect of preferential TMRM accumulation in mitochondria, and of TMRM photoactivation, individual organelles displayed sharp transient depolarizations caused by local reactive oxygen species (ROS)-mediated gatings of the mitochondrial permeability transition pore (PTP). In COS-7 cells, such directed repetitive gatings of the PTP gave rise to stochastic delta Psi(m)flickering at the level of individual organelles, but also to prominent synchronous delta Psi(m)transitions in whole subgroups of the mitochondrial population, indicative of the existence of an underlying electrically coupled mitochondrial network.
View Article and Find Full Text PDFDev Neurosci
February 2001
INSERM EMI 9929, Université Bordeaux 2, Bordeaux, France.
The expression of an enzymatic deficiency in a metabolic network can present a biochemical threshold. This threshold can be characterised thus: (1) a low activity of the enzyme can sustain a normal flux, but (2) a minute further decrease of its activity makes the flux collapse. We give simple mathematical models displaying such a behaviour, and we apply the models to some examples of oxidative phosphorylation dependency on respiratory chain complex deficiency.
View Article and Find Full Text PDFAnesthesiology
August 2000
Laboratoire d'Anesthésiologie (INSERM EMI 9929), Université Victor Segalen Bordeaux 2, France.
Background: Highly lipophilic local anesthetics interfere with mitochondrial energy metabolism. These metabolic effects could, in part, explain some toxic effects of local anesthetics, such as bupivacaine-induced myocardial depression. The purpose of this study was to compare the optically pure isomers of bupivacaine on heart mitochondrial bioenergetics.
View Article and Find Full Text PDFLab Invest
July 2000
INSERM EMI 9929, Université Bordeaux II, Rabat-Léon, France.
Mitochondrial pathologies are a heterogeneous group of metabolic disorders that are frequently characterized by anomalies of oxidative phosphorylation, especially in the respiratory chain. The identification of these anomalies may involve many investigations, and biochemistry is a main tool. However, considering the whole set of biochemical data, the interpretation of the results by the traditionally used statistical methods remains complex and does not always lead to an unequivocal conclusion about the presence or absence of a respiratory chain defect.
View Article and Find Full Text PDFJ Biol Chem
November 1999
INSERM-EMI 9929, Université Victor Segalen-Bordeaux 2, 146 rue Léo-Saignat, F-33076 Bordeaux Cedex, France.
Mitochondrial cytopathies present a tissue specificity characterized by the fact that even if a mitochondrial DNA mutation is present in all tissues, only some will be affected and induce a pathology. Several mechanisms have been proposed to explain this phenomenon such as the appearance of a sporadic mutation in a given stem cell during embryogenesis or mitotic segregation, giving different degrees of heteroplasmy in tissues. However, these mechanisms cannot be the only ones involved in tissue specificity.
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