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F Lemonnier

Publications and source records attributed to F Lemonnier.

At least 37 records · Page 2Linked to original sources
PubMed1993

Simultaneous determination of the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their corresponding hydroperoxides obtained by lipoxygenase treatment.

A method for the simultaneous determination of the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their corresponding hydroperoxides is described. Hydroperoxides were formed by incubation of phospholipids with lipoxygenase at pH 9.2. Silicic acid column chromatography (silica Sep-Pak column) was used to separate the phospholipids into phosphatidylcholine and phosphatidylethanolamine. A single C-18 reverse-phase column was employed to separate the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their hydroperoxides by high-performance liquid chromatography. The mobile phase consisted of 5% 10 mM ammonium acetate at pH 5 and 95% methanol. The molecular species of phosphatidylcholine and phosphatidylethanolamine were detected at 205 nm; the eluate was mixed with a chemiluminescence reagent (isoluminol and microperoxidase) and monitored by fluorometry. Under the experimental conditions used, three individual molecular species of both soybean phosphatidylethanolamine and phosphatidylcholine (18:3/18:2, 18:2/18:2 and 16:0/18:2), together with their corresponding hydroperoxides, were identified and quantitated.

Chromatography, High Pressure Liquid↗
PubMed1993

Effects of alpha-tocopherol on antioxidant enzyme activity in human fibroblast cultures.

The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (Cat) were determined in human fibroblast cultures at four concentrations of exogenous alpha-tocopherol: 0.2, 2.5, 10 and 50 micrograms/ml of culture medium, or without alpha-tocopherol. Relationships between alpha-tocopherol levels and the activities of SOD and GPx were identified. The cellular alpha-tocopherol level correlated with GPx activity (p < or = 0.01) and inversely correlated with SOD activity (p < or = 0.003), but only when alpha-tocopherol was added to the culture medium. The variations in the cellular GPx/SOD ratio depended on the level of cellular alpha-tocopherol (p < or = 0.001). Furthermore, there was a strong inverse correlation between SOD and GPx activity (p < or = 0.0001). Cat activity did not correlate either with cellular alpha-tocopherol concentration, or with SOD or GPx activity. These results underline the complex interplay between alpha-tocopherol and other antioxidant systems in human fibroblast cultures.

Catalase↗
PubMed1992

H-2-restricted cytolytic T lymphocytes specific for HLA display T cell receptors of limited diversity.

We previously showed that H-2Kd-restricted cytotoxic T lymphocyte (CTL) clones specific for a single nonapeptide derived from the Plasmodium berghei circumsporozoite (PbCS) protein displayed T cell receptors (TCRs) of highly diverse primary structure. We have now analyzed the TCR repertoire of CTLs that recognize a peptide derived from the human class I major histocompatibility complex (MHC) molecule HLA-Cw3 in association with the same murine class I MHC molecule H-2Kd. We first sequenced the TCR alpha and beta genes of the CTL clone Cw3/1.1 and, based on this genomic analysis, the TCR alpha and beta cDNA junctional regions of 23 independent H-2Kd-restricted CTL clones specific for HLA-Cw3. The results show that the TCR chains display very limited heterogeneity, both in terms of V alpha, J alpha, V beta, and J beta segments, and in terms of length and sequence of the CDR3 alpha and beta loops. The TCR repertoire used in vivo was then analyzed by harvesting CTL populations from the peritoneal cavity of immune mice. The peritoneal exudate lymphocytes (PELs) displayed HLA-Cw3-specific cytolytic activity in the absence of any stimulation in vitro. Remarkably, most of these freshly isolated PELs expressed TCRs that shared the same structural features as those from HLA-Cw3-reactive CTL clones. Thus, our results show that a peptide from HLA-Cw3 presented by H-2Kd selects CTLs that bear TCRs of very limited diversity in vivo. When taken together with the high diversity of the TCRs specific for the PbCS peptide, these findings suggest that natural tolerance to self peptides presented by class I MHC molecules may substantially reduce the size of the TCR repertoire of CTLs specific for antigenic peptides homologous to self.

Amino Acid Sequence↗
PubMed1992

Progress toward the development of an implantable sensor for glucose.

The development of an electrochemically based implantable sensor for glucose is described. The sensor is needle-shaped, about the size of a 28-gauge needle. It is flexible and must be implanted subcutaneously by using a 21-gauge catheter, which is then removed. When combined with a monitoring unit, this device, based on the glucose oxidase-catalyzed oxidation of glucose, reliably monitors glucose concentrations for as long as 10 days in rats. Various design considerations, including the decision to monitor the hydrogen peroxide produced in the enzymatic reaction, are discussed. Glucose constitutes the most important future target analyte for continuous monitoring, but the basic methodology developed for glucose could be applied to several other analytes such as lactate or ascorbate. The success in implementation of such a device depends on a reaction of the tissue surrounding the implant so as not to interfere with the proper functioning of the sensor. Histochemical evidence indicates that the tissue response leads to enhanced sensor performance.

Biocompatible Materials↗
PubMed1991

2-Deoxy-D-glucose uptake and fatty acid content in fibroblast cultures from children with syndromic paucity of interlobular bile ducts (Alagille syndrome).

2-Deoxy-D-glucose (2-DOG) uptake was studied in skin fibroblast cultures from control children and children with Alagille syndrome or syndromic paucity of interlobular bile ducts (PILBD). No significant differences in uptake were observed between patients and controls. However, as the scatter of the results was larger in the fibroblasts from patients, we attempted to establish for these patients a relationship between 2-DOG uptake and some biochemical parameters. We observed an inverse relationship between this uptake and the levels of plasma cholesterol and phospholipids (r = -0.85). Compared to controls, 2-DOG uptake was significantly lower in cultures from patients who had very high levels of cholesterol (P2 group), but not in cultures from patients with moderately increased levels of cholesterol (P1 group). The level of total cellular cholesterol in cultured cells from the P1 and P2 groups was not significantly different from the control level, but we found marked differences between the concentrations of fatty acids. In the cultures from patients (especially the P2 group), we observed a significant increase in total fatty acids; among the saturated fatty acids, this increase chiefly concerned the 18:0 (14%) and among the polyunsaturated the n - 3 fatty acids (55%). The high concentrations of 20:5, 22:5 and 22:6, which enhance membrane fluidity, might explain the decrease in 2-DOG uptake found in the cultures from patients (P2 group) with PILBD. The nature of these abnormalities might be connected with the genetic origin of Alagille syndrome.

Bile Ducts↗
PubMed1991

Free thyroxin measured in dried blood spots from normal, low-birth-weight, and hypothyroid neonates.

We have adapted a new radioimmunoassay for free thyroxin (FT4) measurement in dried blood spots for use in neonatal screening for hypothyroidism. The method is easy, fast, and cheap. Within-assay and between-assay CVs are respectively 9.6% and 13.2%. In 997 neonates three days postpartum with normal thyrotropin concentrations, the mean FT4 concentration was 27.2 pmol/L (SD 7.3 pmol/L). There was no significant difference in mean FT4 concentration between boys and girls. FT4 concentrations increased linearly with birth weight or with gestational age, as expressed by multiple linear regression: FT4 (pmol/L) = 0.0016 birth weight (g) + 0.6931 gestational age (weeks) - 4.8772. Only gestational age significantly affected the FT4 value. For five hypothyroid infants tested on day three postpartum, FT4 values were all below the 1st percentile of values from healthy neonates. Thus, when the neonatal concentration of thyrotropin is above normal, FT4 measured in the same sample can provide a reliable earlier diagnosis of hypothyroidism.

Birth Weight↗
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↗
PubMed1990

Vitamin E deficiency and lipoperoxidation during adult respiratory distress syndrome.

Vitamin E (Vit E) is an important component of the lung's defense against oxidant injury. The aim of this study was to determine a) if adult respiratory distress syndrome (ARDS) was associated with a decrease in Vit E plasma level linked to an enhancement of plasma lipoperoxidation, and b) if this Vit E deficiency might be explained by malnutrition and/or a consumption defect. Vit E, lipoperoxides (LP), total lipids, and fatty acid plasma levels were measured in 12 patients with ARDS (PaO2 less than or equal to 60 Torr with FIO2 0.6 on mechanical ventilation). At the onset of ARDS (T0), the decrease in Vit E plasma level was significant (p less than .001) 7.73 +/- 0.54 (n = 12) vs. 11.46 +/- 0.55 mg/L (n = 7) in the control group (healthy subjects breathing room air). A significant (p less than .05) increase in LP was simultaneously observed (4.12 +/- 0.35 [n = 12] vs. 2.94 +/- 0.30 nmol/ml [n = 17]) in the control group. At T0, LP were inversely correlated with Vit E plasma levels (r = .78, p less than .01). Vit E deficiency was associated with low levels of total plasma lipids (3.68 +/- 0.25 g/L) and plasma cholesterol (0.97 +/- 0.07 g/L). Thus, the Vit E/total lipids ratio (2.18 +/- 0.17 mg/g) was always above the accepted normal limit value for this ratio (0.8 mg/g).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[A new strategy of neonatal screening for cystic fibrosis. The association of immunoreactive trypsin and molecular biology in dried blood].

Cystic fibrosis (CF) screening by means of immunoreactive trypsin (IRT) lacks specificity: only 1 out of 12 hypertrypsinemic neonates has cystic fibrosis. We propose here to analyse the KM.19 polymorphic site in the dried blood spots as an additional test in hypertrypsinemic neonates. A blind retrospective study of 114 hypertrypsinemic samples has been performed after polymerase chain reaction. Twenty-seven of 37 CF (74%) were homozygous for allele 2 (2-2) and could have been diagnosed on the 15th day of life. Fifty-five percent of the infants tested were homozygous for allele 1 (1-1), a very rare feature in CF, conferring them a probability of being normal of 99.8%. At the moment, this test could be of great help in the CF screening, even better than the search for the delta F508 mutation for which 45.9% of CF patients are homozygous.

Cystic Fibrosis↗
PubMed1989

Trypsin-binding immunoglobulin G and associated antigen in cystic fibrosis.

Trypsin-binding immunoglobulin G (TBIgG) is found in the sera of a high proportion of patients with cystic fibrosis. We previously reported that TBIgG preferentially binds human cationic trypsin rather than trypsin from other animal species. Binding affinity is enhanced by complex formation with bovine pancreatic trypsin inhibitor, which is known to induce characteristic conformational modifications in the active site region of the trypsin molecule. To identify the human trypsin-like antigen associated with TBIgG, we have studied the effects of conformational changes of cationic trypsin induced by limited proteolysis based on competitive binding studies. It is shown that the most likely TBIgG-related self-antigen is an 11,000-dalton fragment that is a cleavage product of the complex formed by trypsin and alpha 1-protease inhibitor. This result emphasizes the occurrence of circulating trypsinogen activation and is interpreted to be a consequence of the protease-antiprotease imbalance, which has been well documented by previous investigators in cystic fibrosis and also in other lung diseases associated with an inflammatory state.

Binding, Competitive↗
PubMed1988

Hybrid genes between HLA-A2 and HLA-A3 constructed by in vivo recombination allow mapping of HLA-A2 and HLA-A3 polymorphic antigenic determinants.

HLA-A2 and -A3 genes have been modified in their third exon (second domain) by using in vivo recombination. In this method Escherichia coli are transfected with a plasmid which contains two highly homologous sequences (e.g., the third exons of HLA-A2 and -A3) and has been linearized by cleavage between these two sequences. Circularization takes place in the bacteria by homologous recombination leading to hybrid A2-A3 sequences. The analysis by DNA sequencing of a number of such recombinants shows that they indeed occur by homologous recombination (no insertions or deletions) and that the probability of crossing over decreases as the distance from the free end of DNA in the homologous region increases. No double recombinants were observed. These hybrid exons were reinserted into either HLA-A2 or HLA-A3 genes, thus generating a panel of functional hybrid genes containing one or several HLA-A2 specific substitutions in an HLA-A3 background or vice versa. These genes were expressed by transfection into murine P815-high transfection efficiency recipient cells. Serologic analysis leads to the conclusion that expression of polymorphic antigenic determinants specific for HLA-A2 (detected with M58, A2A28M1, and CR11.351 mAb) is linked to the presence of threonine residue (amino acid (AA) 142) and/or histidine residue (AA 145) and valine residue (AA 152). The expression of specific HLA-A3 polymorphic determinants (recognized by GAP-A3 mAb) is correlated with the existence of a asparagine residue (AA 127) and a aspartic residue (AA 161). But aspartic residue 161 contributes with glutamic acid residue 152 in the formation of the A3 epitope recognized by the anti-A3 mAb X1.23.2.

Antibodies, Monoclonal↗
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

Free triiodothyronine measured in dried blood spots from normal, low-birth-weight, and hypothyroid neonates.

Free triiodothyronine (FT3) has rarely been studied in neonates, primarily because of obvious problems in obtaining serum samples from neonates for research purposes. We adapted an analog radioimmunoassay for measuring FT3 in dried blood samples and used it to assay 361 samples selected from those collected for the screening for neonatal hypothyroidism. The mean FT3 concentration in healthy neonates on the fourth postpartum day is 2.55 pmol per liter of whole blood (SD 0.78 pmol/L, n = 145), the same as in healthy adults. Low-birth-weight infants have a decreased concentration of FT3, and this decrease is much greater in premature neonates than in infants at low weight for gestational age. In six hypothyroid newborns, the FT3 concentration was normal or increased, clearly indicating that FT3 assay is not a diagnostic tool for hypothyroidism. FT3 was barely detectable in one case of congenital galactosemia.

Humans↗
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↗