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M Bernard

Publications and source records attributed to M Bernard.

At least 217 records · Page 12Linked to original sources
PubMed1985

31P-NMR study of high-energy phosphorylated compounds metabolism and intracellular pH in the perfused rat heart.

Using 31P-NMR and haemodynamical measurements, this work assesses different aspects of myocardial preservation improvement during a global ischaemia, based on a simultaneous and correlated study of high-energy phosphorylated compounds, intracellular pH and left ventricular function. Isolated perfused working rat hearts were subjected to 2 or 3 h of hypothermic ischaemia followed by 30 or 45 min of reperfusion. A study of the influence of pH and buffer used in cardioplegic solutions has demonstrated a better preservation of high-energy phosphates and an improved functional recovery when using a pH 7.0, glutamate - containing solution. Protection provided by cardioplegia can be enhanced by the appropriate use of a fluorocarbon-oxygenated cardioplegic reperfusate. The use of nifedipine, a calcium antagonist, in the cardioplegic solutions, does not provide any additional protection under hypothermic conditions.

Adenosine Triphosphate↗
PubMed1985

Carbon-13 and phosphorus-31 NMR study of hepatic metabolism in the perfused rat liver.

Phosphorus-31 nuclear magnetic resonance (NMR) has been used to determine non-invasively absolute concentrations of phosphorylated metabolites in the perfused rat liver. It has been shown that the NMR method does detect cytoplasmic ATP and ADP (ATP:ADP ratio of 15 +/- 3) with no contribution from mitochondrial adenine nucleotides. The concentration of ATP was 7.2 +/- 0.3 mM in the cytosol of well-oxygenated liver, after two hours of perfusion with a Krebs-Ringer buffer. Other phosphorylated metabolites were detected, mainly inorganic phosphate (1.1 mumol/g liver wet weight), phosphorylcholine (1.0 mumol/g wet weight), glycerophosphorylethanolamine (0.34 mumol/g wet weight) and glycerophosphorylcholine (0.30 mumol/g wet weight). The intracellular pH measured from the position of the Pi resonance has a value of 7.2 +/- 0.1. It is likely that the detectable Pi originates from the cytosolic compartment since a pH value of 7.4-7.6 would be expected for the mitochondrial matrix. Natural abundance carbon-13 NMR has also been used to follow the glycogen breakdown in situ by measuring the intensity of the glycogen C-1 resonance in the perfused liver spectrum as a function of the perfusion time. The glycogenolytic process has been studied as a function of the glucose content of the perfusate. Rate of glycogenolysis from 2.7 to 0.16 muEq glycosyl units g wet weight-1 min-1 were found when glucose concentration in the perfusate was varied from 0 to 50 mM. The fate of 90% enriched [2-13C] acetate has been studied in the perfused rat liver by 13C-NMR in order to investigate the mitochondrial metabolism and the interrelations between cytosolic and mitochondrial pools of metabolites. Some compounds of the intermediary metabolism where found to be extensively labelled, e.g. glutamate, glutamine, acetoacetate and beta-hydroxybutyrate. Under our experimental conditions, labelling of glutamate reached a steady-state within 30 min after the onset of perfusion of 20 mM acetate. In addition, the observed incorporation of carbon-13 isotope into glutamine can be linked to the operation of the glutamate-glutamine antiporter and to the high activity of the cytosolic glutamate synthetase. The finding of both active glutaminase and glutamine synthetase activity in the same liver cells is an evidence of the existence of an active glutamine-glutamate futile cycle.

Acetates↗
PubMed1985

Influence of the pH of cardioplegic solutions on intracellular pH, high-energy phosphates, and postarrest performance. Protective effects of acidotic, glutamate-containing cardioplegic perfusates.

The common practice of using alkalotic cardioplegic solutions is not supported by experimental evidence. The present study was conducted to assess the effects of varying the pH (7.00, 7.40, and 7.70 at 20 degrees C) of a glutamate-containing cardioplegic solution on intracellular pH, high-energy phosphate content, and postarrest functional recovery and to compare the effects of various buffers (glutamate, bicarbonate, TRIS, and histidine) at a given pH (7.00 and 7.40). Isolated perfused rat hearts were subjected to 2 hours of cardioplegic arrest at 15 degrees C followed by 30 minutes of reperfusion. Intracellular pH and high-energy phosphate content were measured at 4 minute intervals by phosphorus 31 nuclear magnetic resonance spectroscopy. These data were correlated with postischemic recovery of function. There was no significant difference between the intracellular pH values recorded at the end of arrest in the three glutamate-containing groups. However, the acidotic solution (pH 7.00) resulted in better preservation than the alkalotic solution (pH 7.70), as evidenced by a higher creatine phosphate content at the end of arrest (61% +/- 9% of control values versus 30% +/- 9% [mean +/- standard error of the mean], p less than 0.05), a higher adenosine triphosphate content at the end of reperfusion (102% +/- 5% versus 82% +/- 6%, p less than 0.05), and a faster recovery of aortic flow (at 3 minutes of reperfusion, 91% +/- 11% versus 51% +/- 11%, p less than 0.05). Subsequent comparison of buffers showed that bicarbonate, TRIS, and histidine were equally effective in maintaining intracellular pH close to control values during arrest. Conversely, the use of glutamate resulted in a more pronounced fall in intracellular pH, which correlated with a better preservation of adenosine triphosphate and a better functional recovery than in the other groups. Overall, the greatest extent of preservation was provided by the pH 7.00 glutamate-containing cardioplegic solution. We conclude that additional protection can be conferred to the cold, chemically arrested heart by combining mild intracellular acidosis, which lowers metabolic needs during arrest, most likely through a limitation of calcium overload, and provision of glutamate, which may act as a substrate for anaerobic energy production while allowing intracellular pH to be kept within the appropriate range.

Adenosine Triphosphate↗
PubMed1985

[Nuclear magnetic resonance spectroscopy. New tool for investigating cellular metabolism in living systems].

Nuclear magnetic resonance spectroscopy is increasingly used to study cellular metabolism in a manner respecting cell integrity. The contribution of phosphorus-31 and carbon-13 NMR is discussed and illustrated by specific examples taken from work carried out in this laboratory or from the literature. A particular emphasis is layed on metabolite identification, quantitation and fluxes as studied by phosphorus-31 NMR which provides a direct insight of energy metabolism. The analysis of perfused rat liver by natural abundance carbon-13 NMR illustrates the potential of the method of study non-invasively lipid and carbohydrate metabolism in living systems. The use of carbon-13 enriched substrates to pinpoint a specific pathway of the intermediary metabolism is described in the case of excised rat heart and liver perfused with (2-C13)-acetate. Clinical applications of NMR spectroscopy are rapidly reviewed.

Adenine Nucleotides↗
PubMed1985

[Traumatic tricuspid insufficiency. Review of the literature, apropos of a case].

The authors report a case of traumatic tricuspid incompetence due to rupture of an anterior pillar and the chordae, associated with pericardial rupture, a first degree atrioventricular block, a persistent complete right bundle branch block and acute recurrent pericarditis. The diagnosis, suggested by echocardiography was confirmed by right cardiac catheterisation. The patient underwent tricuspid plasty six months after the accident. On the basis of a review of the literature, the authors discuss traumatic tricuspid incompetence (its symptoms and associated lesions), the diagnostic methods and the therapeutic approach.

Adult↗
PubMed1984

[Azoles. 12. Pyrazole carbolic acid thioamides].

Morpholids, N-methylpiperazids, piperidids and pyrrolidids of 5-methyl, 3,5-dimethyl-1-phenyl-4-pyrazolthioacetic acid and 3,5-dimethyl-1-phenyl-4-pyrazolcarbonic acid 4-12 are obtained by the Willgerodt-Kindler procedure. The oxothioamids 13-19 result as the intermediate products of the synthesis of thioamids 4-10. The compounds 4, 5, 8, 9, 11, 14 and 17 do not respond to Mycobacterium tuberculosis H37Rv. The thioamids 4, 8 and 11 are of slight toxicity (LD50 greater than 2.8 g/kg, albino-Swiss mice) and inhibit the Carrageenin oedema of the Wistar rat claw minor than phyenylbutazon and indometacin.

Animals↗
PubMed1984

[Cardiac manifestations of Lyme disease. Apropos of 2 cases].

Lyme disease, a well-known entity in the United States, has featured only rarely in the French literature. We report two cases from the Cardiology Department with acute symptomatic atrio-ventricular block. The illness begins with migratory chronic erythema, which is the best marker of the condition. This is followed by neurological, joint and cardiac manifestations. Cardiac involvement consists essentially in A-V block of varying severity, which rapidly regresses. Until the recent discovery of the arthropod vector responsible (Ixodes dammini), the diagnosis was clinical and was confirmed by negative serological results for the other infectious agents. Penicillin and tetracycline are effective at the skin lesion stage. It is important to recognise this condition since there is no case of complete A-V block lasting longer than 2 weeks.

Adult↗
PubMed1983

On the specificity of the two forms of human serum alpha-L-fucosidase.

All normal sera exhibiting either normal or low activities contain two forms of alpha-L-fucosidase (F1 and F2). These two forms, isolated from either type of serum, have respectively similar properties, but the low-activity sera contain a major proportion of the thermolabile, less-acidic form, F1. The specificities for natural substrates (glycoproteins and oligosaccharides) and for synthetic fucosides have been studied. All types of alpha-L-fucosidase linkages (1,2; 1,3; 1,4 and 1,6) are split by the form F2. The specificity of the form F1 is more restricted. Only alpha(1,3) and some types of alpha(1,2) and alpha(1,4) fucosyl linkages are split.

Carbohydrate Conformation↗
PubMed1981

Properties of two forms of alpha-L-fucosidase isolated from normal human sera with low and high enzymatic activity.

Studies on human alpha-L-fucosidase were performed on normal and low activity sera. After DEAE-Sephacel chromatography, two major forms of enzyme have been characterized in both types of sera. These enzymatic forms were different with respect to their thermostability and electrofocusing behaviour. The less acidic form (I) was thermolabile. In contrast, the more acidic one (II) was thermostable. But the forms I and II had respectively similar properties when isolated from either normal or low activity sera. These results suggest the presence in both types of sera of two major forms of alpha-L-fucosidase but in variable proportions. The low activity sera contained a major proportion of the thermolabile less acidic form when compared with normal activity sera.

Chromatography, Ion Exchange↗
PubMed1980

[Corneoscleral trabecular collagen. Ultrastructural changes and immunotyping in chronic and cortisone-induced glaucoma].

Ultrastructural changes in connective matrix of corneoscleral trabeculum in primary open-angle glaucoma and corticosteroid-induced glaucoma are described. Four forms of collagen fibers were observed: typical, hyper-, segmented fibers and cross-banded collagen. Light and electron microscopy, using antibodies against collagen types, demonstrates the presence of type I collagen widely distributed in trabecular connective matrix and type III collagen in perivascular zones. Type IV collagen is located on basal membranes on endothelial lamina. In glaucomatous disease, the ultrastructural aspect of connective matrix reflects a continuous remodelling process associating fibrolysis and fibrogenesis.

Adolescent↗