PubMed Health⌕ Search

Biomedical subjects

M Maugras

Publications and source records attributed to M Maugras.

At least 19 recordsLinked to original sources
PubMed2001

Interactions of surfactants with living cells. Induction of apoptosis by detergents containing a beta-lactam moiety.

The toxicity of new surfactants containing a beta-lactam ring has been established by studying their interaction with a hybridoma cell line. An hour of contact is sufficient to generate an apoptotic signal after two days of culture. Under the experimental conditions chosen for the experiments, surfactants have been divided into three categories: i) biocompatible and non-apogenic; ii) surfactants triggering an apoptotic signal without inducing cell necrosis; iii) surfactants triggering an apoptotic signal at low concentrations and destroying the cells by necrosis at higher concentrations. The necrosis inducing surfactants also had haemolytic properties. These properties were related to the values of the hydrophilic-lipophilic balance of the molecules.

Animals↗
PubMed2001

Possible effects of counterions on biological activities of anionic surfactants.

The aggressiveness in terms of apogenic and necrotic activities of lysine-derived anionic surfactants towards a mammalian cell line (U937) were studied. We used N(alpha)N(epsilon)-dioctanoyl lysine as the model surfactant with lysine, tris, Na(+) or Li(+) as counterions. The aggressiveness of the different surfactants was assessed as the concentrations leading to apoptosis or necrosis after the cells were incubated in the presence of surfactants and then cultivated in their absence. Used in the same conditions, acetates associated with the same cations, had no effects on the cells. Our results show that the aggressiveness of the surfactants depended on the nature of the counterions: it was high when surfactants were associated with small counterions, and low with large counterions.

Anions↗
PubMed1999

Erythrocyte hemolysis and shape changes induced by new lysine-derivate surfactants.

The effects of new synthetic lysine-derived anionic surfactants on human and rat erythrocytes were studied. The surfactants were salts of Nalpha,Nepsilon-dioctanoyl lysine with different counterions: lysine (77KK), tris (trishydroxymethyl amminomethane) (77KT), sodium (77KS), and lithium (77KL). 77KK and 77KT showed a biphasic hemolytic behavior in the erythrocytes. The surfactants 77KS and 77KL showed concentration-dependent hemolysis with a CH50 of about 3.4 and 2.6 mmol/l, respectively. 77KK and 77KT induced protection against hypotonic hemolysis in rat erythrocytes at the concentration which showed the least hemolytic activity under isotonic conditions. With human erythrocytes, 77KT did not show biphasic behavior in isotonic medium, but under hypotonic conditions biphasic behavior was present. Changes in shape of the erythrocyte, from discocytic to stomatocytic were observed after incubation with the anionic surfactants studied. Such shape changes occurred progressively over time, with total alteration in shape occuring after about 20 min of incubation.

Adult↗
PubMed1996

Effects of lipid supplementation of culture media on cell growth, antibody production, membrane structure and dynamics in two hybridomas.

Membrane lipid organization and membrane fluidity affect cell functions. The effects of supplementing culture media with a lipid mixture (Ex-Cyte) containing cholesterol, phospholipids and fatty acids on cell growth, antibody production and membrane composition and dynamics in two hybridoma cell lines were studied. A49 cells decreased immunoglobulin production but cell growth increased. Lipids had no effect on the cell growth rate of B9 cells but increased immunoglobulin production and productivity. The fluidity of the deep areas of the plasma membrane and cytoplasmic organelles increased in the two cell lines. There was increased fluidity of the polar regions of the plasma membrane and a decreased phosphatidylethanolamine/phosphatidylcholine ratio in A49 cells. B9 cells underwent no change in fluidity of the polar regions but the phosphatidylinositol content was increased, together with higher monoclonal antibody production. These results demonstrate that antibody production is not linked to the dynamic properties of the membrane, even though changes in the membrane phosphatidylinositol content are associated with the final step of antibody secretion, but that the action of phospholipids and fatty acids on cell growth is membrane-associated.

Animals↗
PubMed1995

Hybridoma cell cultures continuously undergo apoptosis and reveal a novel 100 bp DNA fragment.

This report represents an investigation into the nature of apoptosis in hybridoma cultures and its significance to their utilization in biotechnology. To this end DNA fragmentation and capillary electrophoresis of genomic DNA was studied during the culture of two hybridoma cell lines. This indicated that the phenomenon of apoptosis was always present even under normal culture conditions. Two DNA fragments not associated with the typical DNA fragmentation ladder were identified in the two hybridoma cultures: a previously unreported DNA fragment of about 100 bp and a large fragment which may correspond to one reported in the literature (Walker et al., 1993). The small fragment was identified as soon as the early exponential growth phase of culture, while the large fragment appeared only in the latter part of the growth curve when there was marked DNA fragmentation. In addition we present evidence that aurintricarboxylic acid, which inhibits apoptosis in neural cells, permits this process in hybridoma cells at levels below 100 microM. This unusual predisposition of hybridoma cultures to undergo apoptosis and their response to inhibitor of apoptosis may have important implications for approaches to the culture of hybridomas and their utilization for monoclonal production.

ABO Blood-Group System↗
PubMed1993

Increase of hybridoma productivity using an original dialysis culture system.

Hybridoma cell growth and monoclonal antibody production were investigated with a laboratory-made system in which cells were grown in dialysis tubing (MW cut-off 25 kD). The dialysis system contained 10 ml of cell suspension and was immersed in 200 ml of culture medium which when replaced or was at 4-day intervals. With this system, monoclonal antibody concentrations similar to those observed in ascites (concentrations in the order of one gram per liter) were obtained. With no medium replacement, the antibody production was 3.3 g/l and the cell productivity 3.2 x 10(-8) micrograms of IgM produced per cell in one minute. With medium replacement the antibody production was higher, 4.4 g/l but the cell productivity was lower, 1.49 x 10(-8) micrograms per cell in one minute. Cells cultivated in non-optimized conditions were better producers than cells growing in a good environment.

Animals↗
PubMed1992

Use of fluorescence anisotropy determinations for indicating the physiological status of hybridoma cell cultures.

The evolution of lipid compartment fluidity during culture of hybridoma cells was studied by fluorescence polarization measurements. The probe partition between the plasma membrane and intracytoplasmic compartments was determined by a quenching fluorescence method. A progressive decrease of the plasma membrane fluidity was observed during the growth phase with an increase during stationary and degeneration phases of the culture. These data suggest that fluidity parameters could be used to follow the behaviour of hybridoma cell cultures.

Cell Membrane↗
PubMed1989

[Cell cycle analysis of hybridoma cultures: study by cytofluorimetry].

An hybridoma cell line cultivated in flasks has been used as a model to study the loss of cell viability in high density cell cultures. Cell cycle analysis by cytofluorimetry has shown that a new hypochromosomic cell population appeared as soon as the viability began to decrease. However there is no evidence that this new population is constituted of dead cells.

Animals↗
PubMed1988

[Highly purified, functionally active human fibronectin preparation].

Fibronectin has been purified by gelatin-Sepharose affinity chromatography from fresh frozen human plasma. The bound fibronectin was eluted with 3 M urea. The purity of the fibronectin obtained has been checked on (immunoelectrophoresis, polyacrylamide gel electrophoresis, FPLC). Biological activity of the purified molecule has been monitored by means of three assays: quantitation of the gelatin-binding activity by ELISA, quantitation of the fibronectin-mediated attachment of fibroblasts on plastic and evaluation of the opsonic activity (uptake of gelatin latex particles by a murine macrophage line). When deep-frozen, fibronectin retains all of its properties. This highly purified and functional fibronectin fulfills the basic requirements for a standard reagent. It will allow to investigate physicochemical and functional alterations of various fibronectins.

Cell Adhesion↗
PubMed1984

Cell surface modifications with trifluoromethyl dinitrophenyl-soluble protein conjugates: immunogenic role of noncovalently bound hapten.

Bovine serum albumin (BSA) was derivatized, under mild conditions, with trifluoromethyl-dinitrophenyl (CF3-DNP), a haptenic group cross-reacting with trinitrophenyl (TNP). High-field nuclear magnetic resonance of fluorine (19F-NMR) permitted to calculate the number of covalently and noncovalently bound haptenic groups per BSA molecule. Further dialysis against paratoluene sulfonic acid permitted to obtain CF3-DNP-BSA conjugates from which noncovalently bound hapten had been removed. Soluble conjugates containing 4 covalently bound plus 1 noncovalently bound hapten groups, or only 4 covalently bound groups, were added to splenocytes in culture. These splenocytes, after such treatments, were added to effector lymphocytes in a 5-day culture aimed at the generation of cytotoxic T lymphocytes (CTL) against the CF3-DNP-induced cell surface modification antigens. It was found that only the BSA conjugates that contained noncovalently bound haptens were able to generate CTL against target cells whose surface had been directly modified with CF3-DNP, whereas BSA bearing only covalently bound hapten groups were not. Replacing BSA by human serum albumin, or CF3-DNP by TNP, gave comparable results. Thus, under the conditions used, haptenic groups covalently bound to their soluble carrier protein did not generate hapten-dependent CTL, but noncovalently bound or free haptenic groups at very low concentration were able to do so.

Antigens, Surface↗
PubMed1983

Cell-surface antigenic modifications with trinitrophenyl sulfonate versus trifluoromethyl-dinitrophenyl sulfonate.

The aim of the work was to justify the use of trifluoromethyl-dinitrobenzene sulfonate (CF3-DNBS) modification rather than trinitrobenzene-sulfonate (TNBS) modification, so as to be able to take advantage of the presence of fluorine atoms in the analogue, which allow the analysis of the hapten-carrier bonds by 19F-NMR nuclear magnetic resonance. Cell-surface antigenic modifications brought about by exposure to TNBS or CF3-DNBS were found to be immunologically cross-reactive, both in cell-mediated lymphocytotoxicity and in indirect immunofluorescence. The extent of haptenic derivatizations was found to be of the same order of magnitude, as appraised both by quantitative-absorption studies or by using radioactive hapten, provided that the less chemically reactive CF3-DNBS was used at the concentration of 10 mM and TNBS at the concentration of 1 mM. However, only TNBS-modified cells were sensitive to destruction by antibody-plus-complement-mediated cytotoxicity.

Animals↗
PubMed1983

[Visualization of different types of hapten-cell membrane interaction by fluorine high-field nuclear magnetic resonance].

Using a high field spectrometer (5.9 Tesla) 19F-NMR spectrum of soluble material from 4 trifluoromethyl 2,6 dinitrobenzene sulphonate (CF3-DNBS) treated murine lymphocytes was recorded. CF3-DNBS is a fluorinated analog of 2,4,6 trinitrobenzene sulphonate (TNBS), and these compounds have been found to create cross-reacting antigenic modifications of cell surface. At least 4 distinguishable signals have been detected, and we think that 19F-NMR could be used to study, at a molecular level, some immunochemical problems concerning modification with TNBS.

Animals↗
PubMed1982

Differential variations of sensitivities of TNP-modified lymphoma cells to lysis by cytotoxic lymphocytes and by antibodies.

Cultured RDM4 cells were modified with 1 mM trinitrobenzene sulphonate (TNBS) and assayed for lysis by either in vitro generated cytotoxic T-lymphocytes (CTL) or complement-mediated humoral immunity. It was observed that cells harvested from the exponentially growing phase culture (as assessed by an important incorporation of thymidine) were more sensitive to CTL, but less sensitive to humoral immunity, than cells harvested from resting phase culture. Radiolabelled [14C]TNBS permitted to show that exponentially growing cells bound about 5 times less TNBS than cells at the resting phase. It is therefore concluded that the efficiency of the CTL on TNP-modified cells is not proportional to the density of TNP-groups on the targets, and that CTL on the one hand, and complement-mediated humoral immunity on the other hand, must have very different cell surface requirements to be able to lyze the targets.

Animals↗
PubMed1979

The hepatic cytochrome level in the cat (Felis catus): normal value and variations in relation to some biological parameters.

1. The average level of the hepatic hydroxylating cytochrome was determined in the cat (0.380 +/- 0.085 nmol.mg-1 proteins). 2. Great individual differences were noted. 3. The level of cytochrome increases with age in the immature (age less than or equal to 8.5 months) and young adults (age: 10-18 months). It is diminished in the older animals. 4. The measured average level is lower than that in other species, and approaches the human one. 5. The induction capacity of phenobarbital is lower in the cat than in other mammals, for example the rat or the mouse.

Aging↗
PubMed1977

[Use of measurement of liver cytochrome P 450 as a water toxicity test].

The authors describe a new approach to determine the toxicity of water samples. The level of liver hydroxylating cytochrome in mice injected with water samples is assayed. This assay is used to test the toxicity of waters containing an earth extract (humic and fulvic acids). The water samples showed various toxicities desinfected with chlorine or ozone.

Animals↗
PubMed1975

Microbial transformation of artificial estrogens of the allenolic group.

When 2,2-dimethyl 3-(2'-naphthyl 6'-hydroxy) pentanoic acid, an artificial estrogen of the allenolic acid group, was added to an exponential-phase growth culture of Neurospora crassa (in Horowitz medium), it was transformed into its hydroxylated derivative, 2,2-dimethyl 3-(2'-naphthyl 4',6'-dihydroxy)pentaoic acid. To study this transformation, radioactive 2-methyl-[2-14-C=A1methyl 3-(2'-naphthyl 6'-hydroxy) pentanoic acid has been prepared. The rate of metabolism of allenolic acids varies in the same way as their estrogenic activity.

Carbon Radioisotopes↗