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Biomedical subjects

M Gautier

Publications and source records attributed to M Gautier.

At least 55 records · Page 3Linked to original sources
PubMed1991

Respective effects of glucose and glutamine on the glutamine synthetase activity of human skin fibroblasts.

The activity of Glutamine Synthetase (GS) was measured during the growth of human diploid skin fibroblasts cultured for three weeks in the presence or absence of either glucose or glutamine or both. In medium free of both glucose and glutamine, a single late peak in GS activity was observed concomitantly with delayed small cell protein increment. In all media containing either glucose or glutamine or both. GS activity rose sharply during rapid cell growth, displayed a plateau, and then decreased once the cells had reached confluency. The variations in extracellular amino acid levels were also determined and were found to depend on the composition of the medium but not on the cell culture duration. These results demonstrate, for the first time as far as we know, that strong GS activity is present in rapidly growing skin fibroblasts. In contrast to many other mammalian cell types, GS activity in human skin fibroblasts appears not to be subject to regulation by extracellular glutamine. This difference may well be connected with cell differentiation.

Amino Acids↗
PubMed1991

Normal expression of thymidine kinase and O6-methylguanine-DNA methyltransferase in cultured fibroblasts from individuals with hereditary galactokinase deficiency.

Expression of the enzymes galactokinase, thymidine kinase, and O6-methylguanine-DNA methyltransferase is occasionally coordinately regulated in human cell lines. We have measured the activities of these three enzymes in extracts of fibroblasts from individuals with hereditary galactokinase deficiency. These cells do not express measurable galactokinase activity. The levels of O6-methylguanine-DNA methyltransferase were in the normal range in cells from three galactokinase-deficient individuals. The activity of thymidine kinase in the affected cells was in the normal range for two of the three individuals. The reduced thymidine kinase activity in the third individual reflected the extremely poor growth of the cells in culture. Immortalization of one galactokinase-deficient cell line resulted in loss of O6-methylguanine-DNA methyltransferase activity, but the galactokinase and thymidine kinase levels remained unchanged. The data indicate that the loss of galactokinase activity in these individuals is the consequence of an alteration of gene expression which does not involve coordinate silencing with the thymidine kinase and methyltransferase loci.

Cell Line↗
PubMed1989

Cholesterol and prostaglandin synthesis by cultured human skin fibroblasts in the Alagille syndrome involving paucity of interlobular bile ducts.

Children with Alagille syndrome show high serum cholesterol (15-20 mmol/L). To establish correlation of this unusual level of cholesterol with the regulation of cholesterol metabolism, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) activity and synthesis of cholesterol, fatty acids and acidic steroids from [14C]acetate were determined in cultured skin fibroblasts from 2-3 year old children. Prostaglandin E2 (PGE2) synthesis and nucleic acid synthesis were determined in cells when they were growing in medium containing normal, Alagille or fetal bovine serum. These values were similar to values of controls. HMGR activity was found to be similar in cells of control and children with the syndrome, whether the cells were incubated in lipoprotein-deficient or normal medium. Incorporation of acetate into cholesterol was inhibited to a greater extent by lipoprotein-containing medium in control than in children with the syndrome. Fatty acid synthesis was similar in all conditions. 1-7% of the recovered lipid radioactivity in cells and medium separated as acidic steroids. Serum from a donor patient, when included in the medium, did not affect PGE2 or nucleic acid synthesis compared with normal human or fetal bovine serum. The data suggest that cells of children with Alagille syndrome may have a membrane defect of transfer of cholesterol (LDL receptor defect) leading to excessive cholesterol synthesis. Also, synthesis of acidic steroids (bile acid-like material) and their secretion into the medium occurs in normal fibroblasts and those from children with the syndrome.

Acetates↗
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

Glutamine dependency of human skin fibroblasts: modulation by hexoses.

The combined effects of carbohydrates and glutamine were investigated in diploid strains of normal human skin fibroblasts cultured for 21 days under eight different culture conditions: hexose-free medium or medium containing D-glucose, D-galactose, or D-fructose, with or without added glutamine. Cell growth, hexose consumption, lactate production, intracellular glycogen content and extracellular amino acid levels were measured every third to fourth day. In the presence of glutamine, cells reached a higher saturation density in fructose medium than in glucose or galactose medium but per cell consumption of fructose and galactose was much less than that of glucose. Consumption of all three carbohydrates per unit cell growth exhibited three distinct phases: Days 1-3, 3-10, and 10-20, respectively. In the absence of glutamine the rate of cell growth was not altered in glucose or galactose medium, but slowed down considerably in fructose medium. Glutamine deprivation also led to changes in hexose consumption. In hexose-free media the cell growth rate at first was very slow, but rose after 2 or 3 weeks of culture. The levels of extracellular nonessential amino acids varied according to medium and growth phase. One of the most exciting findings was that human fibroblasts are able to maintain a slight excess of glutamine in all media not supplemented with glutamine and, more surprisingly, to synthesize it in a medium containing galactose and glutamine.

Amino Acids↗
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↗
PubMed1988

Factor VIII procoagulant antigen in human tissues.

The localization of factor VIII procoagulant antigen (VIII:Ag) and factor VIII von Willebrand antigen (VWF:Ag) was investigated in human liver, lung, spleen, placenta and umbilical cord, by an immunoperoxidase technique using an avidin biotin complex (ABC). Positive staining for VIII:Ag was observed in the endothelial cells of liver sinusoids, veins and arteries, as well as in the endothelial cells of placenta, lung and spleen. VWF:Ag was detected in the vascular endothelial cells of all the organs explored. The staining intensity of both VIII:Ag and VWF:Ag varied in the different tissues and showed a distinctive pattern of distribution in the liver. VIII:Ag was also observed in the cytoplasm of dysplastic, foetal-like hepatocytes which infiltrated one liver specimen. Our results agree with the view that liver endothelial cells are a major site of Factor VIII (F VIII) storage and secondary release into the circulation. However, the bright staining intensity of VIII:Ag and VWF:Ag in the lung and placenta suggests that these two tissues might also be a substantial source of F VIII.

Antigens↗
PubMed1987

Glomerular mesangiolipidosis in Alagille syndrome (arteriohepatic dysplasia).

Alagille syndrome is characterized by the association of chronic cholestasis with a paucity of interlobular bile ducts and a distinctive facies together with cardiovascular, skeletal and eye abnormalities. We examined the kidneys of 26 patients with this syndrome; 22 were under 3 years of age and 4 were 4, 6, 12 and 17 years old, respectively. Eighteen showed glomerular lesions of variable severity characterized by a mesangiolipidosis. In the 8 lesser affected patients light microscopy (LM) disclosed a fibrillar appearance of the mesangium, and electron microscopy (EM) showed lipid vacuoles widespread in the mesangial matrix. In the 10 patients who were affected to a greater degree LM and EM showed, in addition to the mesangial matrix changes, the presence of mesangial foam cells. Clinical signs of renal involvement were mild in all patients except for one who died from chronic renal failure at 8 months of age. The extent of mesangiolipidosis was not related to age but to the degree of cholestasis, the most severe lesions being observed in patients aged 3, 6, 8, and 14 months. The glomerular lesions observed in Alagille syndrome are strikingly similar to those observed in adults with lecithin-cholesterol acyl transferase deficiency and other conditions characterized by an increase in plasma lipoproteins rich in free cholesterol and in phospholipids. We conclude that glomerular involvement should be added to the characteristic features of Alagille syndrome. Also we found that the lipid deposition in the glomeruli of patients with Alagille syndrome is related to an abnormal lipid metabolism, which is the consequence of severe cholestasis. The most striking feature of our study is the early detection of the glomerular lesions, contrasting with the lack of overt clinical renal disease. Renal failure may be a major complication for patients with this syndrome in adulthood.

Adolescent↗
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

Syndromic paucity of interlobular bile ducts (Alagille syndrome or arteriohepatic dysplasia): review of 80 cases.

We have observed two types of paucity of interlobular bile ducts (PILBD) in children with chronic cholestasis: the syndromic type, which is more frequent (80 cases), and the nonsyndromic type (31 cases). Study of patients with syndromic PILBD has enabled us to recognize five major features: peculiar facies (95%), chronic cholestasis (91%), posterior embryotoxon (88%), butterfly-like vertebral arch defects (87%), and peripheral pulmonary artery hypoplasia or stenosis, either isolated or associated with complex cardiovascular abnormalities (85%). By observing these major features, it is possible to differentiate the "complete" syndrome, in which all five features are present (26 cases), from the "partial" syndrome, in which only four (42 cases) or three (12 cases) major features are present. Other less frequent features were observed in patients with complete or partial syndrome: growth retardation (50%), mental retardation (16%), renal disturbances, other vascular malformations, bone abnormalities, high-pitched voice, and delayed puberty. Death occurred in 21 (26%) patients with syndromic PILBD. Therapy consisted of supplementation of medium-chain triglycerides and fat-soluble vitamins and administration of cholestyramine or phenobarbital. An autosomal dominant mode of transmission, with variable penetrance, seems likely.

Bile Ducts, Intrahepatic↗
PubMed1987

Permissive role of n-6 polyunsaturated fatty acids on carbohydrate oxidation in human infant skin fibroblasts: one possible mechanism of their intervention on coronary heart disease and diabetes.

UNLABELLED: Many publications indicate the beneficial effect of n-6 polyunsaturated fatty acids (n-6 PUFAs) in the control of coronary heart disease and diabetes, although the mechanism is not clear. Some of our previous results suggest that, in contrast to other lipids, n-6 PUFAs could have a permissive effect on carbohydrate oxidation. To check this hypothesis, we determined pyruvate dehydrogenase (PDH, decarboxylase: EC 1.2.4.1) activity in infant skin fibroblasts (ISF) incubated 6 hours in the presence of 0.25 mM linoleic (LI) or arachidonic (AR) acid, compared to oleic acid (OL) and control ISF incubated without addition of fatty acids. The four groups of cells were preincubated 36 hours either in the presence of fetal bovine serum (FBS), or in the presence of lipoprotein-deprived serum (LPDS). RESULTS: (1) When the ISF were maintained in the medium containing FBS, the two PUFAs had little inhibitory effect on PDH activity, in contrast with the effect of OL. (2) When the ISF were kept in the lipoprotein-deficient medium, PDH activity was low in controls and in the OL cells, but the addition of LI or AR increased the activity. This suggests the role of n-6 PUFAs in enhancing carbohydrate oxidation, under certain conditions.

Arachidonic Acids↗
PubMed1987

Plasmid-Determined Systems for Restriction and Modification Activity and Abortive Infection in Streptococcus cremoris.

Streptococcus cremoris strain IL964 possessed a restriction and modification (R/M) activity which resulted in a bacteriophage efficiency of plating of 5 x 10. Phage sensitivity of protoplast-induced plasmid-cured derivatives indicated that two plasmids called pIL103 (5.7 kilobases) and pIL107 (15.2 kilobases) were each coding for one R/M system. Plasmid pIL103-encoded R/M was ascertained by transfer into the plasmid-free, R/M strain IL1403 of S. lactis, using protoplast cotransformation. This procedure failed for pIL107 because of some degree of incompatibility between pIL107 and the indicator plasmid pHV1301 used in cotransformation experiments. We also observed that plasmid pIL105 (8.7 kilobases) which showed no incidence on phage sensitivity in the parental strain IL964, mediated abortive infection in strain IL1403. In 97% of the infected cells, the phage infection was abortive, while in the remaining 3% phages were produced with a decreased burst size (50 instead of 180).

Journal Article↗
PubMed1986

Insulin dependence of M2 pyruvate kinase in primary culture of human liver.

In the basal state, the presence of L pyruvate kinase (LPK) was constantly observed in primary human liver cell cultures initiated from explants, when cells were examined by immunofluorescence and double labelling. After short-term insulin incubation, M pyruvate kinase (MPK) appeared. Therefore, both LPK and MPK were located in the same cells. We previously obtained the same results in isolated rat hepatocytes in which we demonstrated that short-term regulation of M2PK by insulin was a function of dose and/or incubation time. The present work established that similar conditions govern the regulation of this isozyme in vitro in human hepatocytes.

Cells, Cultured↗