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F Demaugre

Publications and source records attributed to F Demaugre.

At least 37 records · Page 2Linked to original sources
PubMed1991

Infantile form of carnitine palmitoyltransferase II deficiency with hepatomuscular symptoms and sudden death. Physiopathological approach to carnitine palmitoyltransferase II deficiencies.

Reported cases of carnitine palmitoyltransferase II (CPT II) deficiency are characterized only by a muscular symptomatology in young adults although the defect is expressed in extra-muscular tissues as well as in skeletal muscle. We describe here a CPT II deficiency associating hypoketotic hypoglycemia, high plasma creatine kinase level, heart beat disorders, and sudden death in a 3-mo-old boy. CPT II defect (-90%) diagnosed in fibroblasts is qualitatively similar to that (-75%) of two "classical" CPT II-deficient patients previously studied: It resulted from a decreased amount of CPT II probably arising from its reduced biosynthesis. Consequences of CPT II deficiency studied in fibroblasts differed in both sets of patients. An impaired oxidation of long-chain fatty acids was found in the proband but not in patients with the "classical" form of the deficiency. The metabolic and clinical consequences of CPT II deficiency might depend, in part, on the magnitude of residual CPT II activity. With 25% residual activity CPT II would become rate limiting in skeletal muscle but not in liver, heart, and fibroblasts. As observed in the patient described herein, CPT II activity ought to be more reduced to induce an impaired oxidation of long-chain fatty acids in these tissues.

Blotting, Western↗
PubMed1990

Immunoquantitative analysis of human carnitine palmitoyltransferase I and II defects.

Carnitine palmitoyltransferase deficiency realizes two distinct clinical forms. We previously showed and confirmed in the present work that CPTII (identified as the carnitine palmitoyltransferase activity assayable in detergent conditions) is decreased in the muscular form whereas it is unaffected and CPTI is decreased in the hepatic form. The antibody previously prepared against human liver mitochondrial CPTII recognizes the same enzyme in muscle, liver, and fibroblasts. Immunoprecipitation experiments were performed in fibroblasts from patients with the muscular and hepatic forms of the defect. As compared with controls, cell lines from two patients with the hepatic form of the defect did not exhibit any qualitative nor quantitative abnormality of cross-reacting material, whereas cell lines from two patients with the muscular form of the defect exhibited a decreased amount of cross-reacting material. These data suggest that CPTII deficiency could result from a decreased production of protein. The amount of cross-reacting material in the two sets of patients only correlates with CPTII activity, which is decreased in the muscular presentation and unaffected in the hepatic form. These results strengthen the hypothesis of distinct proteins supporting CPTI and CPTII activities.

Acyltransferases↗
PubMed1989

Phytanic acid alpha-oxidation and complementation analysis of classical Refsum and peroxisomal disorders.

We have measured the production of 14CO2 from exogenous [1-14C] phytanic acid in fibroblast monolayers from patients with classical Refsum's disease and peroxisomal disorders. Activities in the different disorders were (percentage of control): classical Refsum's disease (5%), isolated peroxisomal acyl-CoA oxidase deficiency (75%), Zellweger syndrome (4%), neonatal adrenoleukodystrophy (5%), and rhizomelic chondrodysplasia punctate (3%). Absence of complementation was demonstrated between Zellweger syndrome and infantile Refsum's disease lines after polyethylene glycol fusion, with decreases of average activity of 11% relative to unfused cell mixtures. Classical Refsum's disease, rhizomelic chondrodysplasia punctata, and neonatal adrenoleukodystrophy lines all complemented one another, and Zellweger syndrome or infantile Refsum's disease lines, with average activity increases of 522%-772%. No intragenic complementation was observed within either group. Four complementation groups were detected suggesting that at least four genes are involved in phytanic acid alpha-oxidation: one gene for the enzyme phytanic acid alpha-hydroxylase (probably mitochondrial); one gene for a regulatory factor for the expression of phytanic acid alpha-decarboxylation activity and two membrane-bound peroxisomal enzymes involved in the synthesis of plasmalogens; two genes for the assembly of functional peroxisomes and/or import of proteins into peroxisomes.

Adrenoleukodystrophy↗
PubMed1989

Normal muscle CPT1 and CPT2 activities in hepatic presentation patients with CPT1 deficiency in fibroblasts. Tissue specific isoforms of CPT1?

Human carnitine palmitoyltransferase (CPT) deficiency results in 2 clinical forms: a more common "muscular form" with myoglobinuria with or without delayed or impaired ketogenesis and a rare "hepatic form" with hypoketotic hypoglycemia, encephalopathy and seizures without muscular manifestations. We present 2 patients, a male (patient 1) and a female (patient 2) with infantile "hepatic" CPT deficiency and previously documented CPT1 deficiency in fibroblasts. In patient 2, a deficiency of "total" CPT activity in liver had also been previously documented. We set up an isotope exchange assay system that effectively differentiated CPT1 and CPT2 activities in muscle. We found normal CPT1 and CPT2 activities in our patients under near saturating substrate conditions. The CPT1 and CPT2 activities were suppressed to a strikingly similar degree under different kinetic conditions as compared to control muscle and were found to have similar Km values for carnitine and PCoA. With Km concentrations of carnitine, the mean residual activities of CPT1 for patients 1 and 2 were 49 and 44%, respectively (control range 40-53%); the mean residual activities of CPT2 were 60 and 46%, respectively (control range 49-59%). With Km concentrations of PCoA, the mean residual activities of CPT1 for patients 1 and 2 were 52 and 58%, respectively (control range of 52-59%); mean residual activities of CPT2 were 54% and 56%, respectively (control range of 51-68%). When the Vmax concentration of PCoA was doubled and bovine serum albumin reduced to 0.1%, the mean residual activities of CPT1 for patients 1 and 2 were 69 and 63%, respectively (control range 60-80%). In "muscular" patients, a marked absolute deficiency of CPT2 activity (less than 12% residual) was found with an apparent increased sensitivity to suppression of enzymatic activity when the Km concentration of carnitine was used. We suggest that CPT1 and CPT2 may be separate proteins. Furthermore, CPT1 itself may exist as tissue-specific isoforms being the same protein in liver and fibroblasts and a different protein in muscle. Either could be encoded for by the same or closely related genes.

Acyltransferases↗
PubMed1989

Deficiency of carnitine palmitoyltransferase I.

Defective activity of carnitine palmitoyltransferase I was demonstrated in fibroblasts derived from a patient with hypoketotic hypoglycemia. The level of activity observed was approximately 10% of the control mean. Oxidation of palmitate by intact fibroblasts was reduced to 5% of control values. The patient presented at age 14 months with seizures and was found to have marked hypoglycemia and no ketones in the urine. In response to fasting, she developed hypoglycemia, but the curves for acetoacetate and 3-hydroxybutyrate were flat. Administration of medium-chain triglycerides relieved the hypoglycemia and generated a brisk ketogenesis.

Acyltransferases↗
PubMed1988

Hepatic and muscular presentations of carnitine palmitoyl transferase deficiency: two distinct entities.

Human carnitine palmitoyl transferase (CTP) deficiency results in two different clinical variants, one with "hepatic" and one with "muscular" symptoms. We studied CPT activity and long-chain fatty acid oxidation in fibroblast cell lines from four patients, two from each group. Overall CPT activity was deficient in patients' fibroblasts with the hepatic presentation, as previously demonstrated in patients' fibroblasts with the muscular presentation. The hepatic patients' fibroblasts displayed a CPT1 deficiency which resulted in impaired long-chain fatty acid oxidation. In contrast, CPT1 activity and palmitate oxidation were normal in muscular patients' fibroblasts. In these latter patients, the mutation presumably involved CPT2 activity. These data suggest that CPT deficiency is due to at least two different mutations, resulting in two distinct patterns of clinical and biochemical abnormalities.

Acyltransferases↗
PubMed1986

The effect of adenosine and chloroadenosine on sex differences in the energy metabolism of rat hepatocytes.

The intensity and regulation of metabolic pathways are different depending on the sex of the source animal for hepatocytes isolated from mature rats. In cells from fed animals incubated without exogenous substrate, ATP level and ketone body production are higher in males (+25% and +100%) and lactate production is higher (+64%) in females; oleate enhances mitochondrial pyruvate oxidation in hepatocytes from fed male rats but not from fed females; in cells from starved animals oleate increases gluconeogenesis in both sexes at saturating levels of gluconeogenic substrates. However, at physiological levels (1 mM lactate and 0.1 mM pyruvate), this activation can only be detected in cells from males. In both sexes, oleate activation is abolished by adenosine which reduces in parallel the mitochondrial oxidation of pyruvate; chloroadenosine, an A2-receptor agonist, increases glycogenolysis strongly in hepatocytes from male animals (+80%) but only very slightly in female cells (+12%).

2-Chloroadenosine↗
PubMed1984

Influence of oleate oxidation on pyruvate production and utilization in hepatocytes isolated from fed rats. Effect of 2-[5-(4-chlorophenyl)pentyl]oxiran-2-carboxylate.

Oleate (0.35 and 1.5 mM) decreases, in a concentration-dependent manner, lactate and pyruvate concentrations in hepatocytes, isolated from fed rats, incubated without exogenous substrate. The glycolytic flux, estimated at 18 mM-glucose by [6-3H]-glucose detritiation and apparent production of lactate and pyruvate, is decreased by oleate. The measurement of glycolytic intermediates shows a cross-over at the phosphofructokinase level, which might result from an increased citrate concentration. All those effects are dependent on oleate oxidation in mitochondria, since they are suppressed by 1 microM-2-[5-(4-chlorophenyl)pentyl]oxiran-2-carboxylate (POCA), an inhibitor of the mitochondrial entry of oleate, but not of its uptake by hepatocytes. The decrease of lactate and pyruvate also results from an oleate-induced enhancement of pyruvate utilization by hepatocytes, as shown by the increase of 14CO2 formation from [1-14C]- and [3-14C]-pyruvate, especially at low (0.4 mM) pyruvate concentration. Those oleate effects are also suppressed by POCA. They might be due to an enhanced flux through pyruvate carboxylase and pyruvate dehydrogenase, as a result of an oleate-induced increase in the mitochondrial concentrations of pyruvate and acetyl-CoA. Thus oleate oxidation inhibits production of lactate and pyruvate in fed-rat hepatocytes, as it does in other tissues. But, in the liver, it also enhances the mitochondrial utilization of pyruvate. The physiological implications of those findings are discussed.

Animals↗
PubMed1983

Evaluation of isolated human hepatocytes.

This preliminary study reports the functional capacities of freshly isolated human hepatocytes in regard to their energetic metabolism and monooxygenase activities. Incubated for 30 or 60 min, isolated cells maintain their membrane integrity, ATP and reduced glutathione content and redox potential estimated by means of lactate to pyruvate and beta-hydroxypyruvate to acetoacetate ratios. Three monooxygenase activities, supported by different isoenzymes of cytochrome P-450 are determined by the accumulation of unconjugated metabolites: their relative magnitudes are similar to those observed in microsomes, indicating a good preservation of hydroxylase activities during cell isolation and incubation. Although incubations did not exceed 60 min, one can conclude that human hepatocytes maintain their viability and metabolic capacities after isolation and might be considered in transplantation process for the treatment of acute hepatic failure. Isolated human hepatocytes might be also used as a tool for studying biochemical and toxicological effects of a drug.

Adolescent↗
PubMed1983

Influence of oxalate on the rate of the tricarboxylic acid cycle in rat hepatocytes.

In hepatocytes isolated from fed rats, physiological concentrations of oxalate lower the flux through the tricarboxylic acid cycle (-48%) and reduce the steady-state levels of oxaloacetate and other Krebs cycle intermediates. All the metabolic modifications observed are explained by pyruvate carboxylase inhibition, since oxalate hardly modifies the flux through pyruvate dehydrogenase.

Animals↗
PubMed1983

Comparison of the effects of 2-chloropropionate and dichloroacetate on ketogenesis and lipogenesis in isolated rat hepatocytes.

The respective effects of 2-chloropropionate and dichloroacetate on the pyruvate metabolic crossroads, lipogenesis and ketogenesis, were compared in hepatocytes isolated from fed rats. 2-Chloropropionate acts as an exclusive pyruvate dehydrogenase activator: it increases ketogenesis, lipogenesis, Krebs cycle intermediates and mitochondrial NADH/NAD+ ratio. The effects of dichloroacetate depend on experimental conditions and the intensity of its catabolization into oxalate: the resultant action of dichloroacetate on tested parameters combines the effects of pyruvate dehydrogenase activation on the one hand, and pyruvate carboxylase inhibition by oxalate on the other. A mixture of 2-chloropropionate plus oxalate mimics the effects of dichloroacetate. In hepatocytes from fed rats, endogenous lipogenesis is correlated with the mitochondrial NADH/NAD+ ratio, irrespective of the effector added.

Acetates↗
PubMed1983

Role of the mitochondrial metabolism of pyruvate on the regulation of ketogenesis in rat hepatocytes.

In hepatocytes isolated from fed rats the inhibition of lipogenesis (-80%) by 5-tetradecyloxy-2-furoate (an inhibitor of acetylCoA carboxylase) and alpha-cyano-3-hydroxycinnamate (an inhibitor of pyruvate entry into mitochondria) increases the oxidation of 0.35 mM oleate respectively by 70% and 90%. 5-tetradecyloxy-2-furoate increases ketone body production from oleate only by 30% and has no effect on ketogenesis from octanoate, whereas alpha-cyano-3-hydroxycinnamate mimics the effects of fasting on ketone body production: It increases ketogenesis from 0.35 mM oleate by 90%, from 0.78 mM oleate by 25% and from 1.57 mM butyrate by 37%. alpha-cyano-3-hydroxycinnamate also decreases the activity of tricarboxylic acid cycle and the production of malate and citrate. In hepatocytes from fasted rats, alpha-cyano-3-hydroxycinnamate does not modify ketogenesis from oleate, unless cells are incubated with a mixture of lactate and pyruvate. A lactate and pyruvate mixture decreases ketogenesis from oleate and octanoate and increases citrate and malate production without modifying the uptake of fatty acids. This effect is potentiated by 3-mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase. The results cannot be interpreted only by the effects of malonylCoA on carnitine acyltransferase. They are discussed with respect to the possible involvement of mitochondrial oxaloacetate concentration in the regulation of ketogenesis.

Animals↗