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Biomedical subjects

A Lemonnier

Publications and source records attributed to A Lemonnier.

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

Improved fluorometric determination of malonaldehyde.

Lipoperoxidation is implicated in various pathological conditions. Malonaldehyde (MDA) is the most commonly used marker of this process. We propose simple modifications to Yagi's fluorometric assay for MDA determinations, to avoid long and tedious manipulations by eliminating the first precipitation and washing steps, analogous to HPLC methods, and to increase both the sensitivity and the specificity of the assay by measuring synchronous fluorescence. The proposed technique is easier, faster, and more sensitive than Yagi's method (Academic Press, 1982: Lipid peroxides in biology and medicine). The results obtained with the novel method correlate with those from the HPLC method described by Therasse and Lemonnier (J Chromatogr Biomed Appl 1987;413:237-41).

Chromatography, High Pressure Liquid↗
PubMed1990

Culture of galactosaemic fibroblasts in the presence of galactose: effect of inosine.

Fibroblasts from three galactosaemics had no galactose-1-phosphate uridyltransferase (GALT) activity. These fibroblasts cells were cultured in different media supplemented with dialysed fetal calf serum. Galactosaemic and control cell strains stopped growing in hexose-free medium. In glucose-free medium containing galactose, galatosaemic cells, in contrast to control cells, stopped growing after two days and died. In the same medium supplemented with inosine, they exhibited the same growth pattern as the control cell strains although in the presence of high concentrations of galactose-1-phosphate (Gal-1-P). These findings indicated that the glucose-free medium containing galactose supplemented with dialysed fetal calf serum and inosine, as a ribose donor, was appropriate for further in vitro investigations of galactose metabolism in galactosaemic cells.

Cell Division↗
PubMed1990

Effect of vitamin E on 2-deoxy-D-glucose uptake in human fibroblast cultures.

2-Deoxy-D-glucose (2-DOG) uptake was tested in human fibroblast cultures in the presence and absence of vitamin E. Addition of 10 micrograms/ml vitamin E to the culture medium significantly reduced this uptake for 2-DOG concentrations of 0.005 to 10 mmol/liter (P less than or equal to 0.01). The decrease of 2-DOG uptake was inversely proportional to the rise in 2-DOG concentration (P less than or equal to 0.01). The presence of vitamin E reduced by 71% the average cellular level of lipid peroxides (expressed as thiobarbituric acid reactive substances) and caused a small but significant decrease in the cholesterol concentration (P less than or equal to 0.01). These last results might explain the decrease in 2-DOG uptake observed in the presence of vitamin E.

Biological Transport↗
PubMed1989

Simultaneous determination of hemoglobin and coproporphyrin by second derivative differential spectrophotometry: application to the diagnosis of meconium aspiration.

We describe a simple, fast method for simultaneous measurement of hemoglobin and coproporphyrin in urine and amniotic fluid, by second-derivative differential spectrophotometry. Both pigments were determined in biological samples without prior extraction. Despite the slightly overlapping spectra, the method permitted satisfactory resolution and avoided interspectral interference. Its sensitivity, sufficiently good, allowed to detect hemoglobin and coproporphyrin in slightly pathological urine and amniotic fluid as an aid to the diagnosis of meconium aspiration.

Amniotic Fluid↗
PubMed1989

Cytosolic thymidine kinase activity in cultured human fibroblasts from individuals with galactokinase deficiency.

The structural genes for human galactokinase (GALK) and the human cytosolic form of thymidine kinase (TK1) are located on 17q21-q22. These two loci are tightly linked, and studies on Chinese hamster cell lines have shown that the expression of TK1 and GALK genes may alter simultaneously. We investigated the possibility of a dependent mutation of TK1 and GALK genes in cultured fibroblasts, obtained from two patients homozygous for the GALKG-deficient gene. Since we showed that the TK1 level varies as a function of the passage and the growth rate of a given strain, our experiments were performed on nonstored skin fibroblasts, between the third and the fifth passage for both controls and patients. We found that TK1 levels in GALK-deficient cells were almost 75% of those observed in control strains with a similar growth rate. Previous results in the literature have shown a pronounced decrease in TK1 activity in three GALK-deficient fibroblastic strains. We suggest that these disparities of TK1 levels in GALK-deficient fibroblasts may be related either to genetic heterogeneity of GALK deficiency or to differences in culture conditions.

Cell Division↗
PubMed1989

High hepatic gamma-glutamyltransferase (gamma-GT) activity with normal serum gamma-GT in children with progressive idiopathic cholestasis.

gamma-Glutamyl transferase (gamma-GT) was assayed in the serum and liver biopsies of children affected with either progressive idiopathic cholestasis (PIC, Byler's disease), or other types of cholestatic (biliary atresia, cholestasis of various origins) and non-cholestatic diseases. The mean liver gamma-GT activity was increased significantly only in PIC and biliary atresia. In contrast, the serum gamma-GT activity, raised in children with evident damage to the main bile ducts or to the interlobular bile ducts, was normal in children with PIC. Although the mechanism for such a discrepancy between high liver and normal serum gamma-GT activities in PIC is still speculative, this peculiarity could prove to be of use in leading to a better understanding of the disease.

Biliary Atresia↗
PubMed1989

[Metabolic cooperation in cocultures of fibroblasts from patients with various abnormalities of galactose metabolism].

14C galactose incorporation into the TCA-precipitable material of cultures of fibroblasts deficient in galactokinase (GALK-) was nil. In cultures of fibroblasts deficient in uridyltransferase (GALT-), it was 30 to 75% of control incorporation. In cocultures of GALK and GALT-deficient fibroblasts, 14C incorporation was restored to near-normal levels. This restoration produced in the presence of close cellular contacts was not increased by polyethyleneglycol somatic hybridization. Our results indicate that metabolic cooperation occurred involving the transfer of galactose 1-phosphate from the GALT-deficient to the GALK-deficient cells via intercellular connections.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1989

[Direct spectrophotometric determination of urinary uroporphyrin and coproporphyrin using zerocrossing second derivative spectrophotometry].

The use of zero-crossing second-derivative spectrophotometry allows simultaneous determination of uroporphyrin and coproporphyrin directly in urines. Linearity and repeatability are excellent. Detection limit is about 8 nmol/l. Specificity is excellent too, except in unusual porphyrias where porphyrins with 5, 6 or 7 carboxylic groups are encountered. In such a case, this method allows the detection of increased porphyrins contents. The main advantage of this technique is its simplicity: it needs just to acidify urines and to plot a spectrum from 380 to 440 nm to determine the uroporphyrin and coproporphyrin concentrations. So it may be a very useful technic for clinical biochemistry laboratories in charge of monitoring patients suffering from porphyria.

Coproporphyrins↗
PubMed1988

Plasma prolidase and prolinase activity in alcoholic liver disease.

Prolidase (EC 3.4.13.9) and prolinase (EC 3.4.13.8) activity was measured in the plasma of 53 patients with alcoholic liver disease. Plasma prolinase activity was not correlated with histological characteristics in liver biopsies. In contrast, prolidase activity rose significantly (p less than 0.02) in cirrhotic patients with alcoholic hepatitis in comparison with those without alcoholic hepatitis. It also showed a significant positive correlation with ASAT activity (r = 0.505, p less than 0.001) and with the ASAT/ALAT ratio (r = 0.452, p less than 0.001). Plasma prolidase activity did not allow the differentiation of patients with reversible fibrosis from those with cirrhosis. The interest of this new marker is discussed.

Adult↗
PubMed1988

The Philadelphia variant of galactokinase in human erythrocytes: physicochemical and catalytic properties.

The Philadelphia variant of galactokinase (GALKP) is responsible for an asymptomatic disorder of galactose metabolism. Individuals with GALKP phenotype are common among black people. They exhibit reduced galactokinase (GALK) activity in their red blood cells but normal activity in their white blood cells. We explored the biochemical characteristics of hemolysates from individuals with the GALKP phenotype and from controls. In mixed hemolysates from a control and a proband, the GALK activity measured did not suggest the presence of an inhibitor. We observed that the catalytic properties, pI and thermolability in hemolysates from controls and GALKP individuals were identical. Thus, the Philadelphia variant of galactokinase seems not to alter biochemical properties of the red blood cell enzyme. A silent amino acid substitution, or the dysfunction of a regulatory gene might be likely suggested to explain the reduced enzyme activity.

Black People↗
PubMed1988

The Philadelphia variant of galactokinase: impaired [1-14C]galactose oxidation by intact erythrocytes.

Probands with the Philadelphia variant of galactokinase (GALKP) are black people who exhibit reduced galactokinase (GALK) activity in their red blood cells (RBC), but normal activity in their white blood cells (WBC). This reduced RBC GALK was demonstrated in disrupted erythrocytes. To investigate the possibility of a missing cofactor in hemolysates from individuals with GALKP phenotype, we compared [1-14C]galactose oxidation by intact erythrocytes, with the direct GALK assay in disrupted erythrocytes. The rate of [1-14C]glucose oxidation was also measured in order to differentiate an impaired galactose metabolism from a defect further along the pentose phosphate pathway. A good correlation (p less than 0.001) was found between the direct GALK assay and [1-14C]galactose oxidation in control subjects, which indicates that this method can be used effectively for the detection of GALK defects. This was further supported by studies on samples from heterozygotes and homozygotes for the GALKG deficient gene. For all the probands with a GALKP phenotype, diminished CO2 production from galactose was observed in the absence of impaired glucose metabolism. This allowed us to confirm the existence of a GALK deficiency in intact erythrocytes due to the GALKP variant. Further studies of RBC GALK catalytic properties are needed to investigate the molecular basis of this GALK deficiency.

Blood Glucose↗
PubMed1988

Use of platelets, mononuclear and polymorphonuclear cells in the diagnosis of glycogen storage disease type VI.

We determined glycogen concentration and phosphorylase 'a+b' and phosphorylase a activities in platelets, mononuclear and polymorphonuclear cells from control subjects and patients with phosphorylase kinase deficiency (glycogen storage disease IX) and liver phosphorylase deficiency (glycogen storage disease VI). Variations according to cellular type and to subjects' age (1-40 years) were established. Variable glycogen overloading was found in all our patients. Glycogen storage disease (GSD) VI was characterized by a diminished total phosphorylase activity with a low or normal a/(a+b) ratio of phosphorylase activity. GSD IX was characterized by a very low residual activity of phosphorylase a with an 'a+b' activity low or normal.

Adult↗