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C Charpentier

Publications and source records attributed to C Charpentier.

At least 91 records · Page 5Linked to original sources
PubMed1985

Cell density affects prolidase and prolinase activity and intracellular amino acid levels in cultured human cells.

Prolidase (EC 3.4.13.9) and prolinase (EC 3.4.13.8) and intracellular amino acid levels in cultured human cells increased when cell density rose. Firstly, two normal fibroblast strains were continuously cultured for 21 days and these parameters were measured on days 3, 7, 10, 14, 17 and 21 after plating. Prolidase, prolinase and amino acid levels varied considerably depending on the duration of culture and growth rate. Secondly, we studied the action of different cadmium and cobalt concentrations on prolidase activity. These two effectors altered this enzyme activity, but secondarily to modifying cell density. Thirdly, prolidase activity was investigated in 8 control amniotic cell strains, with a view to prenatal diagnosis of inherited prolidase deficiency, and we noted the same cell density interference. Due to the large variations related to cell density, we recommend specifying the number of cells per unit surface, and avoiding the term 'cells at confluency' which is unduly vague.

Amino Acids↗
PubMed1984

Prolidase and prolidase deficiency.

Prolidase deficiency seems to be a rather rare metabolic disorder. However, many new cases can be detected because screening is easy to perform and enzymatic confirmation allows the differentiation from other iminodipeptidurias . Clinical symptoms are briefly reviewed, while biological considerations and prolidase properties are exhaustively described. Methods for investigating urinary iminodipeptides are given with results. Moreover, several collagen modifications observed in this disorder led us to formulate a hypothesis for their mechanism. Genetic considerations and treatment attempts are discussed.

Amino Acid Metabolism, Inborn Errors↗
PubMed1984

Analysis of dipeptides in urine by gas chromatography/mass spectrometry: implications for collagen breakdown in iminodipeptiduria following a study of the dipeptides by electron impact and chemical ionization.

Dipeptides in the urine of a patient suffering from dermatological purpura, associated with iminodipeptiduria , were determined by gas chromatography/mass spectrometry. The dipeptides were identified as R-proline and R'-hydroxyproline where R is any one of the residues, glycyl, alanyl, valyl, leucyl, isoleucyl, seryl, aspartyl, glutamyl, prolyl, phenylalanyl and R' is alanyl, valyl, leucyl or isoleucyl, seryl, prolyl, glutamyl, phenylalanyl. The predominance of proline- and hydroxyproline-containing dipeptides and the percentage distributions of the other amino acid residues, R and R', strongly implicate an abnormality of collagen metabolism. Structural assignments are confidently based on (a) gas chromatographic retention times, (b) electron impact mass spectra and automatic comparison with reference to spectra stored in a specialized library, (c) chemical ionization mass spectra with isobutane and methanol as reactant gases and (d) the use of deuteriated acetic anhydride as a derivatizing agent.

Adult↗
PubMed1984

Potentiation by piridoxilate of the synthesis of hippurate from benzoate in isolated rat hepatocytes. An approach to the determination of new pathways of nitrogen excretion in inborn errors of urea synthesis.

The synthesis of hippurate from benzoate as compared to ureagenesis has been investigated in isolated rat hepatocytes. Half-maximal synthesis of hippurate was observed at 0.3 mmol/l benzoate. In the presence of 1 mmol/l benzoate, hippurate synthesis proceeded linearly with time at a rate of 40 +/- 10 mumol X h-1 X g-1 dry weight. This provided less than 10% of nitrogen epuration supported by concomitant urea synthesis (350 +/- 82 mumol X h-1 X g-1 dry weight). The incorporation of benzoate to hippurate was markedly limited by the availability of glycine. Half-maximal hippurate synthesis was observed at 2 mmol/l glycine. In the absence of glycine, piridoxilate, a glyoxylate derivative, markedly potentiated hippurate synthesis. Half-maximal stimulation was observed at 10 mmol/l piridoxilate. In the presence of 10 mmol/l piridoxilate, hippurate synthesis (420 +/- 35 mumol X h-1 X g-1 dry weight) provided more than 50% of nitrogen epuration supported by urea synthesis. It is concluded that supplementation with nitrogen-free analogues of glycine such as piridoxilate are required to potentiate hippurate synthesis in an attempt to replace ureagenesis as an alternative pathway of waste nitrogen excretion in inborn errors of urea synthesis.

Alanine↗
PubMed1984

Hudson memorial lecture. Neonatal management of organic acidurias. Clinical update.

Therapeutic guidelines have been obtained from a retrospective review of 41 patients affected with organic acidaemias, 16 patients with neonatal maple syrup urine disease (MSUD), 11 methylmalonic acidaemia, (MMA) seven propionic acidaemias (PA) and seven isovaleric acidaemias (IVA), and by comparing this personal series with similar reported cases. The emergency treatment of these organic acidurias in the neonate has to main goals: toxin removal and anabolism. Anabolism is always promoted by early diet therapy. The best method of toxin removal depends on the nature of the defect; peritoneal dialysis with exchange transfusions or multiple or prolonged exchange transfusions in MSUD and in PA, diuresis and exchange transfusions in MMA and glycine supplementation in IVA. Vitamin supplementation (thiamine 20 mg, biotin 10 mg, B12 2 mg and riboflavin 100 mg) should be tried in all cases although the neonatal forms of these defects are very rarely vitamin responsive. Additional treatments such as carnitine or insulin may prove to be useful.

Acids↗
PubMed1984

Relationship between cell density and prolidase activity in human skin fibroblasts: effects of ascorbate and fructose.

To evaluate the influence of cell density on the activity of fibroblast prolidase (EC 3.4.13.9), we determined this activity in sparse and dense cultures. We also investigated, the effects of different concentrations of beta-D (-) fructose and L (+) ascorbate, which both increased cell density at confluency. For a fructose concentration of 25 mM, we observed that in the absence of glucose, intracellular total proteins increased 1.5-fold and prolidase specific activity, 1.8-fold. For ascorbate, a broad optimum concentration was found (range 0.01 - 0.50 mM). Addition to cultures of 0.1 mM ascorbate increased total proteins 1.4-fold, and doubled prolidase activity. This investigation was prompted by our previous results [J. Metab. Dis. 1983, 6, 27-31], confirmed here, and suggesting that increased prolidase activity at confluency was due to a rise in cell density.

Ascorbic Acid↗
PubMed1984

Plasma prolidase activity: a possible index of collagen catabolism in chronic liver disease.

We describe here an easy method of determining prolidase (EC 3.4.13.9) in plasma after preincubation with Mn2+ for 24 h at 37 degrees C to maximize prolidase activity. The mean activity in 338 patients who were either in hospital or outpatients was 900 U/L +/- 520 (2 SD), unrelated to sex or age. In 25 of these 338 samples tested, prolidase activity was between 1500 and 2000 U/L. It exceeded 2000 U/L in eight, all of whom were patients with chronic liver disease. Plasma prolidase activity was normal in cytolytic syndromes such as liver or heart disease. Of the 27 patients with cirrhosis, only five exhibited prolidase activity greater than 2000 U/L. Plasma prolidase activity was uncorrelated with six biochemical indexes to liver function (the aminotransferases, alkaline phosphatase, glutamyltransferase, total bilirubin, and serum albumin) or with the degree of cirrhotic fibrosis. We believe that plasma prolidase activity may be high only in the early stage of fibrosis. This hypothesis would be consistent with the data on rat-liver collagenolytic activities during CCl4 administration. Monitoring of plasma prolidase activity might be useful in evaluating fibrotic processes in chronic liver disease in the human.

Adolescent↗
PubMed1983

Absence of hepatic molybdenum cofactor: an inborn error of metabolism leading to a combined deficiency of sulphite oxidase and xanthine dehydrogenase.

Five patients with a combined deficiency of xanthine dehydrogenase, sulphite oxidase and, possibly, also of aldehyde oxidase are described. This remarkable coincidence of three inborn errors of metabolism in a single individual was demonstrated to result from a deficiency of the 'molybdenum cofactor', an essential constituent of all three enzymes. The main biochemical findings in these patients included: hypouricaemia, xanthinuria, an increased excretion of sulphite, thiosulphate and S-SUL-sulphocysteine and a decreased excretion of inorganic sulphate. Plasma molybdenum was normal. The ultimate diagnosis was made by the measurement of 'molybdenum cofactor' in a liver biopsy specimen in three out of five patients. The clinical hallmarks in these patients were: feeding difficulties, mental retardation, neurological symptoms, lens dislocation, an abnormal muscle tone, myoclonia and an abnormal physiognomy. The majority of these were already present in the neonatal period. So far, attempts at treatment have been unsuccessful.

Child, Preschool↗
PubMed1983

In-vitro responses to ascorbate and manganese in fibroblasts from a patient with prolidase deficiency and iminodipeptiduria: cell growth, prolidase activity and collagen metabolism.

After successful ascorbate and manganese treatment of a female patient with prolidase deficiency and iminodipeptiduria, we attempted to explain the mechanism of action of these drugs in vitro, using them preferentially on skin fibroblasts. Since in vivo, ascorbate and manganese seemed to be responsible for both biochemical and clinical improvement, they were also expected to activate prolidase activity in vitro. Cell growth and prolidase activity were accordingly observed in fibroblast cultures supplemented with these compounds. It seemed that only ascorbate accounted for the successful in vivo response. To understand the mechanism involved, we studied collagen metabolism and found a decreased proline pool, a massive increase of rapidly degraded collagen and moderate enhancement of type III collagen and type I trimer in the patient's fibroblasts. We believe that ascorbate allowed the prolidase-deficient cells to maintain a normal collagen pool by increasing collagen synthesis. Both the massive increase in cell growth in response to ascorbate and the bad response as regards the quality of the collagen produced confirm the secondary nature of this mechanism. However, the relationship between accelerated collagen catabolism and prolidase deficiency remains unclear.

Adult↗
PubMed1983

Multiple acyl-CoA dehydrogenase deficiency occurring in pregnancy and caused by a defect in riboflavin metabolism in the mother. Study of a kindred with seven deaths in infancy: Value of riboflavin therapy in preventing this syndrome.

Seven infants in one kindred died: one was stillborn; the others, who were floppy at birth and were breast-fed, developed a disorder with the odor of sweaty feet and died in early infancy. In two further pregnancies, 3-hydroxvisovaleric, glutaric, and C6-C10-dicarboxylic acids were demonstrated in the mother's urine during the seventh month. Riboflavin therapy in the last trimester of pregnancy and a riboflavin-rich diet given the infants prevented this syndrome. The presence of abnormal erythrocyte glutathione-reductase activity in the mother while she excreted normal amounts of riboflavin in her urine indicates a probable disorder of riboflavin metabolism resulting in multiple acyl-CoA dehydrogenase deficiency.

Acyl-CoA Dehydrogenases↗
PubMed1982

Optimal conditions for prolidase assay by proline colorimetric determination: application to iminodipeptiduria.

Prolidase assay was reinvestigated by determining proline, using Chinard's method. Although several authors had previously tested this colorimetric reaction, accurate details regarding enzyme activity were not available. The need for greater sensitivity led to the introduction of several modifications: dialysis was eliminated and the substrate concentration and incubation time were changed. In addition, the reaction mixture was preincubated with Mn2+ for 24 h in order to triple prolidase activity. Color development followed at 90 degrees C, because of partial glycylproline hydrolysis at higher temperatures. The effect of several divalent cations on prolidase activity were tested with and without Mn2+. This modified assay was applied to erythrocytes, plasma and skin fibroblasts from a female patient with iminodipeptiduria.

Adult↗
PubMed1982

Biotin-responsive immunoregulatory dysfunction in multiple carboxylase deficiency.

The immunoregulatory system has recently been shown to require prostaglandins (PG) for its activation in man. We report here an impairment of immunoregulatory function, due to defective PGE monocytic production, in a 12-month-old boy with multiple carboxylase deficiency (MCD). The abnormal immune-response was corrected in vitro by adding PGE to the medium. Moreover, PGE deficiency and immunoregulatory dysfunction responded to biotin administration in vivo. It is suggested that the PGE deficiency in MCD could result from an impaired activity of a biotin enzyme, acetyl CoA carboxylase, since the product of this enzyme reaction, malonyl CoA, is required for prostaglandin synthesis.

Biotin↗