Search PubMed⌕ Search

Biomedical subjects

A Lemonnier

Publications and source records attributed to A Lemonnier.

At least 55 records · Page 3Linked to original sources
PubMed1988

Prolinase activity in prolidase-deficient fibroblasts.

The activity of prolinase (EC 3.4.13.8) was studied in cultured skin fibroblasts derived from three patients with deficient prolidase (EC 3.4.13.9). With pro-val as substrate and manganese in the reaction buffer, prolinase activity was higher in prolidase-deficient cells than in control cells (mean (SEM) 917 (67) nmol min-1 mg-1, n = 3, control mean (SEM) 294, (50), n = 11). The Michaelis constants were not different for the pro-val and progly substrates in control and prolidase deficient fibroblasts. However, the constants for Vmax rose for both substrates in deficient cells. These results demonstrate that prolinase activity increases in prolidase-deficient fibroblasts as also shown in the plasma of patients with prolidase deficiency. We suggest that in prolidase-deficient fibroblasts, this rise in prolinase activity constitutes an attempt to compensate for the prolidase deficiency by increasing the greatly reduced intracellular proline pool.

Adult↗
PubMed1988

Plasma fatty acid composition and lipid peroxide levels in children with paucity of interlobular bile ducts.

The total and free fatty acid composition of plasma and lipid peroxide concentrations was studied in 32 cholestatic children with syndromatic paucity of interlobular bile ducts (Alagille's syndrome). The mean lipid peroxide value in these patients was 8.80 +/- 3.70 nmol/ml, nearly 4 times higher than the mean control value. Compared to the control group, the patients exhibited significant variations in total fatty acids, and in particular a relative decrease in linoleic acid (from 29.5 +/- 6.1% in the controls to 19.1 +/- 8.03% in the patients) compensated by an increase in saturated and monounsaturated fatty acids. The plasma lipid peroxide levels were inversely correlated with the unsaturated/saturated fatty acids ratio in total fatty acids, and with the vitamin E status (vitamin E/total lipids). Most of the total and free fatty acid variations observed were largest in patients with severe jaundice. Dietary fat malabsorption and the increase in lipid peroxidation partly explain these results. Furthermore, in free fatty acids, we observed a marked increase in arachidonic acid (from 1.43 +/- 0.85% in the controls to 4.27 +/- 2.24% in the patients), suggesting abnormal eicosanoid synthesis.

Adolescent↗
PubMed1988

Screening of the Philadelphia variant of galactokinase in racially unmixed black Africans: first results.

In previous reports, it was emphasized that the gene GALKA of galactokinase was the predominant allele in white populations and that another allele, GALKP, which reduces red blood cell activity (RBC GALK), was common in black people. In a group of black Americans living in Philadelphia, the frequency of GALKA was found to be very close to values expected from independent estimation of white admixture. The authors have suggested that the ancestors of these blacks might have been virtually all GALKP homozygous. We have looked for carriers of GALKP genotypes among 73 black Africans; only 33 probands were shown to have a low RBC GALK. To detect white admixture, immunoglobulin allotypes Km and Gm were investigated in 50 individuals of the sample; 15 GALKP carriers with low RBC GALK and 30 of 35 individuals with normal RBC GALK shared Gm phenotypes exclusive to blacks. Our work demonstrates for the first time the polymorphism of GALK in black Africans in the absence of white admixture.

Africa↗
PubMed1987

L-proline uptake in human fibroblasts: evidence for a high-affinity system in addition to system A.

Proline uptake was studied in human skin fibroblasts by simultaneous running of kinetic and inhibition experiments on the same cell lines. Two systems for proline uptake were shown: a high-affinity system not inhibited by alpha-(methylamino)isobutyric acid and a low affinity system inhibited by this amino acid (i.e. system A). These results appear to be of interest, firstly because up till now, system A was considered preferable for proline uptake in human fibroblasts, and secondly because they illustrate the need for combined inhibition and kinetic studies of amino acid uptake, especially when the substrate concentration range used and the respective Km of the systems do not allow their detection by kinetic analysis alone. Furthermore, this high-affinity system may have major physiological implications.

Aminoisobutyric Acids↗
PubMed1987

Upper gastrointestinal endoscopy. An unrecognized cause of hyperamylasemia.

The prevalence of hyperamylasemia 2 hr and 24 hr after upper gastrointestinal endoscopy without attempts to cannulate the ampulla of Vater was prospectively studied in 50 consecutive patients. In the 2-hr sample, hyperamylasemia was observed in nine patients (18%) (serum amylase range 59-191 units/liter with a mean value of 102 units/liter; reference range: 12-46 units/liter). Five of the nine patients still had an increased serum amylase (range 54-118 units/liter, mean 78.4) 24 hr after endoscopy. When hyperamylasemia occurred, it always appeared in and was higher in the 2-hr sample. The increased serum amylase activity was due to a rise of S-type isoamylase. The cause of hyperamylasemia after gastrointestinal endoscopy is speculative but is probably due to an hypersalivation.

Adult↗
PubMed1987

Comparative use of glucose and fructose in cultured fibroblasts from patients with hereditary fructose intolerance.

The utilization of fructose and glucose by fibroblast cultures obtained from patients with hereditary fructose intolerance (HFI) was studied in comparison with fibroblast controls. The cell growth, the time course of D-glucose or D-fructose uptake and the consumption of fructose were similar for both HFI and control cells. Some results showed significant differences between these two cell types: HFI cells consumed less glucose, produced less lactate and contained less glycogen than control cells. Furthermore, significantly less [U-14C]D-glucose and [U-14C]D-fructose was incorporated into lipids in HFI cells than in control cells. The mechanisms responsible for these differences observed between the two cell types are not known.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1987

Comparative metabolic effects of fructose and glucose in human fibroblast cultures.

The comparative metabolic effects of fructose and glucose were determined in human fibroblast cultures. Cells were grown in four different media containing 5.5 and 27.5 mM of glucose and fructose, respectively. For these two hexoses, we compared their uptake, consumption, and conversion into 14CO2 and 14C-lipids. D-Fructose was taken up in fibroblasts by an unsaturable process and its consumption was much smaller than that of D-glucose. Whatever the experimental procedure, the glycogen content of cells grown in fructose media was significantly lower than of those grown in glucose media. Labeling of fructose and glucose with 14C showed that more carbon from fructose than from glucose was incorporated into CO2 and glycerolipids. The relative distribution of 14C in the different lipid fractions was similar for both hexoses. These results indicated that the pathways of intermediary metabolism in fibroblast cultures were influenced by the nature of the carbohydrate present in the culture medium and that fructose was a better lipogenic substrate than glucose in human fibroblast cultures.

Carbon Dioxide↗
PubMed1987

Metabolic studies of a sustained galactose overload in rat.

In order to obtain an experimental model for studying inherited disorders of galactose metabolism in man, we administered to adult rats a diet supplemented with 50% of galactose during 38 days. The results showed clinical symptoms such as polyuria, polydipsia, growth retardation and bilateral cataract. The main biochemical features were an increase in the galactokinase and uridyltransferase activities in liver, an ubiquitous accumulation in tissues and a considerable urinary elimination of galactose and galactitol, a weak accumulation of galactose-1-phosphate in tissue and a hyperaminoaciduria. This work led us to quantify the respective importance of the major pathway and minor pathways of galactose in the rat after a galactose-rich diet.

Animals↗
PubMed1987

Determining methemoglobin in blood by zero-crossing-point first-derivative spectrophotometry.

We determined methemoglobin in blood by zero-crossing-point first-derivative spectrophotometry. After lysis of erythrocytes, hemoglobin was converted into oxyhemoglobin and the first derivative spectrum was recorded between 405 and 425 nm. At the exact point where the first-derivative spectrum of oxyhemoglobin was zero ("zero-crossing point"), the first-derivative value of oxyhemoglobin and methemoglobin mixture was proportional to the methemoglobin concentration. The standard curve was linear for all proportions of methemoglobin. Within-assay precision (CV) was 3.4% for a 20% methemoglobin content. Correlation with results by the Evelyn and Malloy method was very good for high proportions of methemoglobin (greater than 10%), but the proposed technique was far better for low methemoglobin percentages because of its linearity, its high sensitivity, and its low detection limit.

Humans↗
PubMed1987

Changes in prolinase and prolidase activity during CCl4 administration inducing liver cytolysis and fibrosis in rat.

In earlier papers, we reported that the activity of prolidase (EC 3.4.13.9) increased in the plasma of patients with cirrhosis, while that of serum prolinase (EC 3.4.13.8) was normal and was affected only by necrosis. In this work, we investigated prolinase and prolidase activity during short and long-term CCL4 administration in the rat. After a single dose, prolinase activity increased in serum faster than did prolidase activity and it also decreased more slowly. Within the liver, no significant change in these two enzyme activities was observed during the acute phase of necrosis. During chronic CCl4 intoxication, the rises in prolidase and prolinase activity in rat serum were difficult to interpret, because of the liver necrosis present throughout the experiment. However, within the liver, prolinase activity was not affected, unlike that of prolidase which rose at week 3, reached a maximum value at week 6 (reversible fibrosis) and remained elevated at weeks 10 and 12 (irreversible fibrosis). The increase in prolidase activity was specific for liver and was not observed in other tissues. These results are in agreement with those obtained in humans; they highlight the possible physiological significance of enhanced liver prolidase activity during the fibrotic process.

Alanine Transaminase↗
PubMed1986

Changes in methionine metabolism induced by D-galactosamine in isolated rat hepatocytes.

We studied several steps of methionine metabolism in isolated rat hepatocytes both with and without the presence of a hepatotoxic agent (D-galactosamine). By use of selective labelling either on methyl or on carboxyl groups, we showed that intracellular methionine is used preferentially for the methylation of phospholipids (42%) and nucleic acids (31%) via S-adenosylmethionine. In the presence of D-galactosamine, the incorporation of L-(14CH3) methionine into macromolecules is significantly inhibited (greater than 50%). This inhibition is associated with a decrease of S-adenosylmethionine and an increase of methionine in the injured cells. These results suggest that hepatotoxicity of galactosamine may be due in part to an inhibition of the methylation of nucleic acids and phospholipids. Consequently, we hypothesize that hypermethioninemia associated with human liver disease could be due, at least partly, to a defect in synthesis and/or utilization of S-adenosylmethionine by hepatocytes.

Adenosine Triphosphate↗
PubMed1986

The use of Ultroser G as a serum substitute in the culture of human skin fibroblasts.

Growth of human skin fibroblasts was dramatically enhanced when serum in the culture medium was replaced by Ultroser G. Compared to the same cells cultured in the presence of serum, alterations in glucose and lipid metabolism and an increase in the activity of prolidase (EC 3.4.13.9) and prolinase (EC 3.4.13.8) were also observed. Consequently, we advise extreme caution in the use of Ultroser G in metabolic studies, especially for periods of culture exceeding 10 days. However, Ultroser G can help to produce a large number of cells and so facilitate purification of the proteins produced during the stationary growth phase.

Ascorbic Acid↗
PubMed1986

[Lipids in the urine after extracorporeal shockwave lithotripsy].

Lipid corpuscles have been found in the urine in about 40 per cent of women (4/10) after extracorporeal shock wave lithotripsy, however this lipuria is very rare in men (1 or 2 per cent of cases) and less pronounced. During three days after treatment, this post-therapeutic lipuria was found to be independent of the age of patients, of the site of the calculi, of their chemical composition or of the number of shock waves administered. This lipuria probably results from the liquefaction of peri-pelvic fat tissue by exothermic reaction. These lipid corpuscles consist mostly of triglycerides and to a lesser extent phospholipids with a very small proportion of cholesterol and fatty acids.

Adult↗
PubMed1986

[Value of derivative spectrophotometry for the determination of plasma and urinary hemoglobin. Comparison with the method using Allen's correction].

We are proposing a technique enabling the dosage of hemoglobin in plasma or urine using spectrophotometry in derivative double dash. Around 420 nm hemoglobin has an elevated molecular extinction factor but the absorption of natural pigments creates a non-negligible interference in the classic spectrophotometric methods. On the contrary, the use of the derivative double dash enables to practically eliminate the background noise and to obtain a specific signal for hemoglobin while keeping an excellent sensitivity. In the plasma, where hemoglobin is entirely linked to haptoglobin, the dosage is done by direct reading (while in the urine the presence of several pigment forms requires the use of Drabkin's reagent. The method is simple, quick, precise and enables to titrate 1 mg.l (or 0.015 mumole.l-1) of hemoglobin. The influence of bilirubin is negligible. The comparison with a method using Allen's correction shows the superiority of the former as far as precision and accuracy are concerned, by avoiding the danger of a non-negligible systematic error.

Hemoglobins↗
PubMed1986

Isolation and characterization of an abnormal alpha slow-moving high-density lipoprotein subfraction in serum from children with long-standing cholestasis.

An abnormal high-density lipoprotein (HDL) subfraction, detected during periods of mild jaundice in the serum of seven children with chronic cholestasis from birth, was isolated and characterized. This fraction, identified by its slow alpha electrophoretic migration, is present in addition to normal HDL and differs from the abnormal HDL previously described in cholestatic syndromes. It is devoid of apolipoprotein B but is precipitated by phosphotungstate-MgCl2. These properties allowed its isolation by double selective precipitation. This subfraction is undetectable with this procedure in the serum of healthy subjects, is rich in cholesterol, and contains a large amount of apolipoprotein E, which may explain its precipitation by phosphotungstate-MgCl2. These apo E-containing HDL may play a major role in the lipid metabolism of patients with long-standing cholestasis during periods of mild jaundice.

Adolescent↗