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Biomedical subjects

A Lemonnier

Publications and source records attributed to A Lemonnier.

At least 91 records · Page 5Linked to original sources
PubMed1983

Influence of two cell harvesting methods on intracellular ATP and amino acid concentrations in human fibroblast cultures.

The intracellular ATP and amino acid concentrations were determined in human fibroblast cultures reaching confluence. The values obtained were very different, depending on the cell harvesting method: trypsinization or scraping. Trypsinization appeared to be the better method for measuring the ATP concentrations (21.25 +/- 0.96 nmol per mg cell protein), this level being much lower with scraping. On the contrary, scraping was the most appropriate method for amino acid measurement. This work underlines the importance of harvesting methods for metabolic studies in human cell cultures.

Adenosine Triphosphate↗
PubMed1983

[Biotin deficiency in the germ-free rat and propionic acidemia].

Biotin deficiency was induced in germ-free rats using three experimental protocols. The results showed the important role of biotin during gestation and suckling. The earlier the deprivation, the earlier the deficiency and the severer the symptoms. In this vitamin deficiency, symptoms occurred that were not observed in the control rats, such as the formation of an intestinal volvulus in rats ingesting an L-isoleucine-supplemented diet. The main biochemical anomalies characteristic of propionic acidemia (ketoacidosis and increased urinary elimination of propionic acid) due to propionyl CoA carboxylase deficiency in man were not observed in the rats that were deprived of biotin for 200 days even after a dietary load of L-isoleucine. Only a small urinary excretion of propionyl-glycine and tiglylglycine was observed. We observed a drop in enzymatic propionyl CoA carboxylase activity in the liver that was proportional to the severity of the vitamin deficiency.

Amino Acid Metabolism, Inborn Errors↗
PubMed1983

Defective galactose oxidation in a patient with glycogen storage disease and Fanconi syndrome.

Carbohydrate metabolism was studied in a child with atypical glycogen storage disease and Fanconi syndrome. Massive glucosuria, partial resistance to glucagon and abnormal responses to carbohydrate loads, mainly in the form of major impairment of galactose utilization were found, as reported in previous cases. Increased blood lactate to pyruvate ratios, observed in a few cases of idiopathic Fanconi syndrome, were not present. [1-14C]Galactose oxidation was normal in erythrocytes, but reduced in fresh minced liver tissue, despite normal activities of hepatic galactokinase, uridyltransferase, and UDP-glucose 4-epimerase in homogenates of frozen liver. These data suggest a defect in hepatic galactose metabolism not so far identified.

Child, Preschool↗
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↗
PubMed1981

Transport of L-alanine in cultured human fibroblasts: evidence for two kinetically distinguishable systems.

The transport of L-alanine in human diploid fibroblasts was investigated. Transport measurements were performed on subcultures between the third and eighth passages with subconfluent cells growing on glass coverslips. Kinetic analysis of approximate initial rates of transport at substrate concentrations from 0.05 to 10 mmole/liter indicate the presence of two distinguishable systems. The high affinity system has a Km of 0.24 mmole/liter and a Vmax of 6.4 nmole/100 micrograms protein/2 min. For the low affinity system, the contribution of the high affinity system to the uptake must absolutely be taken into account. The Km and Vmax values, obtained by using a computer program, are a Km of 15.0 mmole/liter and a Vmax of 14.7 nmole/100 micrograms protein/2 min. For alanine concentrations below 1 mmole/liter, the contribution of the Na+-independent uptake is less than 10%, and the kinetic constants of the high affinity system are in the same range if this contribution is taken into account. On the contrary the influence of a diffusion-like process is more significant on the low affinity system whose Km is about 49 mmole/liter after subtraction of the Na+-independent uptake from the experimental velocities. Inhibition studies were performed with NCH3-alanine. They permitted us first to confirm the existence of system A in cultured human fibroblasts in agreement with two recent works and second to show how this system contributes to L-alanine uptake. This contribution seems very small in low concentrations but it rises as the concentrations increase.

Alanine↗
PubMed1981

D-glucose uptake in human liver cell cultures.

The kinetics parameters for D-glucose uptake were studied in human liver cell cultures under strictly defined experimental conditions. Using a wide concentration range (0.005 to 30 mmol/l), the kinetic data obtained suggested strongly that D-glucose in human liver cell cultures can be transported by two separate systems. For the high-affinity system, the apparent Km was 0.645 +/- 0.21 mmol/l and the Vmax, 12.49 +/- 3.74 nmol/mg protein per min. For the low-affinity system, the apparent Km was 6.91 +/- 0.58 mmol/l and the Vmax, 79.90 +/- 5.27 nmol/mg protein per min. At a concentration of 2.1 x 10(-7) mol/l, cytochalasin B preferentially inhibited the high-affinity D-glucose site or transport system. The time course of D-glucose uptake, studied in two cell lines from patients with hereditary fructose intolerance, was significantly higher than for the control lines.

Biological Transport↗
PubMed1981

Metabolism of sodium [1-14C] and [3-14C] propionate in the non-deficient and biotin deficient rat.

The fixation and elimination kinetics of [1-14C] propionate were studied using autoradiographic technique in the non-deficient and biotin deficient mouse. To quantitate these results, radioactivity was evaluated in the principal organs and excreta over 24 hours from non-deficient and biotin deficient rats, after intravenous injection of sodium [1-14C] and [3-14C] propionate. Radioactivity was eliminated principally via the lungs in the non-deficient rat. Fecal and urinary elimination was weak. Tissular fixation of the radioactivity 24 hours after [14C] propionate injection was carried out principally on the glandular tissues. Almost identical results were obtained in the biotin deficient animal, in which the hepatic propionyl CoA carboxylase activity is decreased by 80 per cent.

Animals↗
PubMed1981

Metabolic abnormalities observed in the rat after administration of sodium dipropylacetate.

Sodium dipropylacetate (DPA) was administered to 10 normally fed rats and 5 biotin-deficient rats. The effects of DPA were measured on propionic acid and glycine levels in urine and blood; and on hepatic propionyl-CoA carboxylase (PCC) activity. No abnormal amounts of propionic acid were found in the blood and urine of the treated rats. Hyperglycinemia and significant constant hyperglycinuria were observed in all animals given DPA, but without significant differences between normal and biotin-deprived rats. DPA treatment did not affect PCC activity in vivo or vitro. These results indicate that the abnormalities of the glycine metabolism are not linked to an accumulation of propionic acid due to PCC inhibition by DPA.

Animals↗
PubMed1981

Liver glycogenosis caused by a defective phosphorylase system: hemolysate analysis.

Investigated were 24 cases of glycogenosis caused by a reduction in liver phosphorylase activity. The intravenous glucagon tolerance test could not discriminate between phosphorylase kinase deficiency [glycogen storage disease (GSD) IX] and phosphorylase deficiency (GSD VI). These two subgroups were distinguished by hemolysate enzyme assays: (1) GSD IX was characterized by a residual phosphorylase kinase activity, a low activation curve for endogenous phosphorylase b and increased amylo-1,6-glucosidase activity. (2) GSD VI was characterized by a normal or increased phosphorylase kinase activity, a slight activation of endogenous phosphorylase b and a normal amylo-1,6-glucosidase activity.

Child↗
PubMed1980

Some metabolic differences between human skin and aponeurosis fibroblasts in culture.

Two types of human fibroblast strains were studied in culture. One was derived from abdomen skin and the other from abdominal muscle aponeurosis. Tissue-specific differences were found between these two cell strains. Skin fibroblasts had faster doubling time, smaller cell volume, and lower glucose consumption when compared to aponeurosis fibroblasts. Furthermore, extracellular amino acid variations showed some specific differences, in particular a lack of serine consumption in skin fibroblasts.

Amino Acids↗
PubMed1980

Glycine transport by cultured skin fibroblasts from a patient with isolated hyperglycinuria.

Glycine transport is studied in cultured skin fibroblasts from a patient with isolated hyperglycinuria and from five normal subjects. Fibroblasts from the patient take up glycine less well than do cell lines from controls. Kinetic studies are consistent with a single transport system in the patient's and controls' cell lines. Vmax value in the hyperglycinuric lines is normal, but the apparent affinity is always reduced as opposed to those of four different control lines separately tested. Statistical analysis shows significant difference between Km values.

Amino Acid Metabolism, Inborn Errors↗
PubMed1980

[Effects of propionic acid metabolic precursors in biotin-deprived rats].

Biotin deficiency induced in the rat, with a biotin-deficient diet but with added avidin involves clinical symptoms of deficiency as well as an important drop (80%) in propionyl-CoA carboxylase activity in the liver, heart and kidneys. But major biochemical anomalies (ketoacidosis and increased urinary elimination of propionic acid), characteristic of propionic acidaemia due to propionyl-CoA carboxylase deficiency in man, are not observed in the rat. Nevertheless, abnormal urinary elimination of methylcitrate and tiglylglycine reflects an appreciable decrease in the metabolism of propionyl-CoA in these animals. The propionyl-CoA load caused by the administration of metabolic precursors of this substance, mainly L-isoleucine, does not induce important biochemical variations except for excretion of propionylglycine.

Animals↗
PubMed1979

[Propionic acidemia and sodium dipropylacetate].

After administering sodium dipropylacetate to normal rats and biotin-deficient rats, we observed a slight hyperglycinemia, significant constant hyperglycinuria, but no accumulation of propionic acid in the blood or significant urinary elimination. Hepatic propionyl-CoA carboxylase activity, in vivo and in vitro, did not change, neither did sodium dipropylacetate inhibit propionyl-CoA carboxylase nor induce propionic acidemia resulting from a deficiency in this enzyme.

Acyl Coenzyme A↗
PubMed1979

[Regulation of glycogen metabolism in the liver and hepatic glycogenosis due to phosphorylase system deficiency].

Glycogen synthesis and breakdown in the liver are tightly controlled through different mechanisms. The purpose of this review is to describe some properties of the enzymes involved in the glycogen metabolism and the sequence of events by which glucose, allosteric effectors and hormones control this metabolism in the liver. Clinical, genetic and biological aspects of the phosphorylase and the phosphorylase kinase deficiencies are examined. The enzymatic analysis of the haemolysates from the patients allows discrimination of these two types of glycogenosis.

Glycogen Storage Disease↗
PubMed1979

[Hereditary abnormalities of galactose metabolism: diagnosis and biochemical supervision (author's transl)].

The authors define the main stages of the biochemical study of hereditary abnormalities of galactose metabolism. They review laboratory examinations for detection, enzyme examinations which provide the diagnostic proof, further examinations which permit one to follow the course and efficacy of a galactose-free diet, the demonstration of genetic variants, the technics of antenatal diagnosis and routine neonatal detection.

Biological Assay↗
PubMed1978

Effect of cycloleucine on amino acid accumulation by human diploid fibroblasts.

Cycloleucine is a synthetic amino acid which produces, in vivo, biochemical abnoramlities comparable to those seen in human cystinuria-lysinuria. The effect of cycloleucine on intracellular accumulation of amino acids overlapping separate transport systems was studied using human diploid fibroblasts subcultures on glass coverslips. The data indicated that alpha-alanine, serine and proline accumulation was inhibited significantly by cycloleucine. The percentage of inhibition was approximately the same. Lysine was less affected by cycloleucine, but this amino acid accumulation proceeded at a rate slower than for neutral amino acids. In vitro, this inhibitory effect seems to be a generalized phenomenon affecting substrates. These results confirm in human fibroblasts data reported for human and rat kidney slices.

Amino Acids↗