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Biomedical subjects

F Lemonnier

Publications and source records attributed to F Lemonnier.

At least 73 records · Page 4Linked to original sources
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↗
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↗
PubMed1979

Study of some enzymatic activities in human liver cell cultures.

Some enzymatic activities were studied in long ter cultures of human liver cells : glucose-6-phosphatase, U.D.P. glucuronosyltransferase, phenylalanine 4-hydroxylase and tyrosine aminotransferase. Only weak tyrosine aminotransferase activity has been found in 12 subcultures, and it has not been increased by addition of corticoids. This tyrosine aminotransferase activity has been measured at different passages of the culture. Our results are compared with those found in literature. The different reasons which could explain the absence of liver specific biochemical functions have been discussed.

Cell Survival↗
PubMed1978

The biologic significance of alloreactivity. The ontogeny of T-cell sets specific for alloantigens or modified self antigens.

We have analyzed the cellular basis of T-cell reactivity against lymphocytes expressing major histocompatibility complex (MHC) products that are foreign by virtue of polymorphism (alloantigens) or because of modification by chemicals or viruses. We find that early in ontogeny, prekiller activity against both trinitrophenyl (TNP)-coupled autologous MHC products and allogeneic MHC products resides in the same (Ly123(+)) T-cell pool; later in ontogeny alloreactivity is invested in Ly23 cells which, when activated, lyse TNP-coupled autologous cells as well as appropriate allogeneic target cells. We demonstrate that stimulation of Ly123(+) T cells in vitro by autologous cells coated with chemically-inactivated Sendai virus results in the formation of Ly23(+) cytolytic T lymphocytes (CTL) that specifically lyse both virus modified autologous target cells and unmodified allogeneic target cells. These results suggest the following model to account for the presence of large numbers of alloreactive T-cell clones in adult animals: continuous stimulation of Ly123 cells by autologous MHC antigens associated with foreign materials such as a virus results in the formation of Ly23 memory progeny carrying receptors that recognize MHC products that are foreign due to genetic polymorphism (alloantigens). In general, these studies indicate that alloaggression (as manifest by Ly23 cells in the CTL response) reflects a high degree of cross stimulation between physiologically relevant antigens, e.g., viral determinants associated with self MHC products, and biologically irrelevant allelic variants of the MHC.

Animals↗
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↗
PubMed1978

The induction of secondary cytolytic T lymphocytes by solubilized membrane proteins.

Membrane-bound antigens responsible for induction of a secondary allogeneic murine cytolytic T-cell (CTL) response have been obtained in a soluble, biologically active form by deoxycholate solubilization of tumor cell plasma membranes. The active proteins are soluble by the criteria of both ultracentrifugation and gel filtration. The immunological specificity of the induced CTL and removal of the activity from solution by treatment with B6 anti-P815 (anti-H-2d) antiserum and Protein A-Sepharose demonstrate that the CTL-inducing activity is dependent upon solubilized major histocompatibility complex antigens.

Animals↗
PubMed1978

Inhibition of the induction of cytolytic T lymphocytes with alloantisera directed against H-2K and H-2D gene products.

Alloantisera directed at gene products of the H-2Kd or H-2Dd loci on the stimulator cell were shown to inhibit specifically the generation of cytolytic T lymphocytes to those antigens. Thus, masking the antigens of one H-2 locus on the stimulator cell inhibits the induction of CTL to products of that locus but does not inhibit the induction of CTL to antigens of another H-2 locus. Alloantisera inhibition of the induction of cytolytic T lymphocytes occurred with both normal and primed responder cells and also occurred when the stimulating antigens were on whole cells or purified plasma membrane. Absorption on the appropriate spleen cells removed the inhibitory capacity of these alloantisera.

Absorption↗
PubMed1978

The induction of cytolytic T lymphocytes with purified plasma membranes.

Subcellular fractions were demonstrated to be effective in stimulating primary and secondary allogeneic CTL responses. 5' nucleotidase activity was used to assess purification of plasma membranes and stimulating activity was found to co-purify with the plasma membrane fraction of the cell. Electron micrographs of these purified plasma membranes showed the majority of the material to be in the form of vesicles of relatively heterogeneous size. The cytolytic T lymphocytes generated by incubation with purified plasma membranes demonstrated immunologic specificity.

Animals↗
PubMed1977

Effects of serum-free culture media on human liver and fibroblastic cells.

The morphological aspects and amino acid variations of human fibroblast and liver cell monolayer cultures were studied in serum free media. Under these conditions, the behaviour of the two cell types differed greatly. The morphological changes for the liver cells, as compared with the fibroblasts, appear more quickly and some of these changes are particular. Furthermore, extracellular amino acid variations are of lesser importance for the liver cells, during the 10 days following the suppression of serum, except for serine.

Amino Acids↗
PubMed1976

Comparative study of extracellular amino acids in culture of human liver and fibroblastic cells.

Amino acid concentration are studied in the extracellular media of ten series of human fibroblast and liver cell monolayer cultures. These two cell types consume and produce ostensively the same amino acids. Among the nonessential amino acids, the most significant variations involve serine and aspartate which are decreased; alpha-alanine, glutamate, ornithine and proline are, on the contrary, increased. Among the essential amino acids, leucine, isoleucine and glutamine are preferentially decreased. The variations of some amino acids are correlated with the cell density. The interrelations which may exist between the variations of these different amino acids are discussed. Furthermore, the glycolytic acitivity of the cells studied is very high: 85% of glucose consumed is found in the form of lactate.

Alanine↗