Biomedical subjects

M T Thébault

Publications and source records attributed to M T Thébault.

7 recordsLinked to original sources

PubMed2000

Coordinated changes of adenylate energy charge and ATP/ADP: use in ecotoxicological studies.

The coordinated variations of the adenylate energy charge and ATP/ADP ratio were modeled and a function that depends on the numerical value of the adenylate kinase-catalyzed reaction has been derived. The model allows sensitive detection of the effects of xenobiotics on adenylate kinase and its cellular environment and offers a robust estimation of the direct or indirect effects of pollutants on the adenylate kinase system: data obtained in laboratory studies on shrimp exposed to cadmium and in field studies on oysters either exposed to polychloro-biphenyl compounds or located in a heavily polluted area indicate that xenobiotics affect the adenylate kinase reaction directly or by changing its cellular environment. These results demonstrate that application of the model to the treatment of ecotoxicological data allows detection of energetic changes that would have been missed by simple analysis of the usual energetic parameters, and should overcome problems encountered in using energetic parameters during assessment of pollution monitoring.

Adenosine Diphosphate↗

PubMed1999

A 31P nuclear magnetic resonance study of the hydrothermal vent tube worm Riftia pachyptila.

31P nuclear magnetic resonance (NMR) was used to study the major phosphorylated compounds visible in perchloric extracts of three body regions of the vestimentiferan worm Riftia pachyptila: winged vestimentum, trunk and segmented posterior opisthosome. Two phosphagens (PGs) were present in vestimentum and opisthosome. The major resonance corresponded to those of phosphoarginine and phosphotaurocyamine, which cannot be discriminated on 31P NMR spectra. We have identified four distinct phosphodiesters (PDEs) in these tissues: glycerophosphorylethanolamine (GPE), serine ethanolamine phosphodiester (SEP), glycero-phosphorylcholine (GPC) and threonine ethanolamine phosphodiester (TEP). Three phosphonates or derivates (PAs) were observed in the three body regions. The minor one was identified as 2-aminoethyl phosphonate (2-AEP). The phosphorus profile of the trunk was appreciably different: one additional resonance in the PDE region and only one phosphagen peak were observed.

Animals↗

PubMed1996

Modelization of coordinated changes of adenylate energy charge and ATP/ADP ratio: application to energy metabolism in invertebrate and vertebrate skeletal muscle.

Regulation of the coordinated adenylate energy charge (AEC) and ATP/ADP ratio variations was studied with the aid of computer-made simulations. When the equilibrium state for the adenylate kinase-catalyzed reaction has been assumed, the function describing the coordinated AEC and ATP/ADP ratio variations can be simply derived from the formulas describing these 2 parameters. The model was used to analyze incidence of AMP deamination in the coordinated regulation of cellular energy metabolism.

AMP Deaminase↗

PubMed1994

Amplification of myoadenylate deaminase during evolution. A comparative study.

Myoadenylate deaminase activity was measured, by using a specific assay technique, in a wide range of animal species, including four invertebrates, one cyclostome, 13 chondrosteans, one teleost and one mammal. The results are discussed considering the known genetic events that have lead to the appearance of the higher vertebrates myoadenylate deaminase molecular form. It is proposed that, during the extensive gene duplication that occurred in the beginning of vertebrate evolution, genetic modification of the myoadenylate deaminase molecule took place in at least two different taxa: the one that evolved to rajiform elasmobranch fishes and the other to the land vertebrates.

AMP Deaminase↗

PubMed1993

Detection of phosphodiester resonances in the perfused heart from vertebrate ectotherms with nuclear magnetic resonance.

In vivo 31P NMR has been used to characterize the phosphorylated compounds present in the heart from vertebrate ectotherms. The perfused hearts from all animals experimented showed prominent resonances between the inorganic phosphate and phosphocreatine peaks. The pattern of these compounds was found to be different in the heart of the different species. As shown by 31P and proton NMR of perchloric extracts, the chemical shift of some of the compounds was characteristic of glycerophosphorylcholine, glycerophosphorylinositol, phosphorylcholine, phosphorylserine, phosphorylethanolamine and phosphoenolpyruvate. The non-identified resonances were found to be phosphodiesters, as demonstrated by alkaline phosphatase hydrolysis. The physiological significance of these high levels of phosphodiesters in the heart from vertebrate ectotherms is discussed.

Alkaline Phosphatase↗

PubMed1987

In vivo 31P NMR in crustacean muscles: fatigue and recovery in the tail musculature from the prawn Palaemon elegans.

31P NMR has been used to observe the in vivo phosphometabolite concentrations in the tail musculature from the prawn Palaemon elegans, at rest and after escape swimming and subsequent recovery. Muscular fatigue corresponds to a 60% breakdown of phosphoarginine, and a 45% increase of sugar phosphates. The pHi fell from 7.10 to 6.86. During recovery, the sugar phosphates and arginine phosphate are replenished after 20 minutes. The ATP concentration did not change throughout the experiment. The pHi was restored within 20 minutes.

Adenosine Triphosphate↗

PubMed1983

Ca2+ ATPase inhibition in trout gill microsomes following in vitro and in vivo treatments with 2,4,5.T.

Bioassay experiments were performed after exposure for 96 hr to various concentrations of trichlorophenoxyacetic acid (2,4,5.T). The sensitivity of juvenile trout was considerably higher than that of mature animals. The activity of the microsomal Ca2+ ATPase in trout gill under the effect of 2,4,5.T was investigated. In vitro studies showed an inhibitory effect on the Ca2+ ATPase, occurring at sublethal concentrations of the herbicide. In vivo exposure to various sublethal concentrations of 2,4,5.T during 96 hr involved a significant inhibition of the microsomal Ca2+ ATPase. The sensitivity of the microsomal Ca2+ ATPase from gills to 2,4,5.T is related to the toxicity of this herbicide.

2,4,5-Trichlorophenoxyacetic Acid↗