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Biomedical subjects

R Girard

Publications and source records attributed to R Girard.

At least 19 recordsLinked to original sources
PubMed1995

Variation of LPS-binding capacity, epitope expression, and shedding of membrane-bound CD14 during differentiation of human monocytes.

The myeloid differentiation Ag CD14 is considered to play a critical role in the binding of LPS to monocytes. To determine if differences in LPS-binding capacities of cells could reflect a variability of CD14 molecules, we analyzed the interactions of various reagents with these molecules in human blood monocytes and in promyelocytic (HL60) and monocytic (THP-1) cell lines. The expression of CD14 epitopes was analyzed with the fluorescent anti-CD14 mAbs My4 and LeuM3. Expression of LPS-binding sites (LPS+ molecules) was detected with LPS-FITC. THP-1 cells stimulated with calcitriol (VitD3), as well as the majority of blood monocytes (50-90%) were My4+/LPS+. However, untreated THP-1 cells, and a substantial population (10-50%) of human monocytes from healthy donors, were My4+/LPS-, thus suggesting the existence of CD14 isoforms with different LPS-binding capacities. In line with this assumption, monocytes stimulated with PMA selectively shed LeuM3+ molecules, but almost no My4+ and LPS+ constituents. Analysis of monocytes after treatment with phosphatidylinositol-specific phospholipase C indicated that among CD14 molecules with LPS-binding capacity, some are susceptible and others are resistant to the enzyme, each type being mainly expressed by a different monocyte subset. Studies of uninduced and chemically induced THP-1 cells showed that wheat-germ agglutinin blocked the binding of My4 to constitutive, but not to chemically inducible CD14. The overall results suggest the existence of at least three different forms of CD14, which may reflect different stages of cell maturation.

Adult↗
PubMed1995

Dielectric properties of grapes and sugar solutions at 2.45 GHz.

Dielectric properties of grapes at 2.45 GHz were measured at moisture contents varying from 80 to 15% (wet basis) at temperatures ranging from 25-80 degrees C using the Open Ended Coaxial Transmission Line Technique. Both dielectric constant and loss factor decreased with decreasing moisture content. In low moisture samples these properties were found to be considerably influenced by higher temperatures. Dielectric properties of sugar solutions of varying concentrations (20-250% by weight in water) were also determined at different temperatures, and these values were compared to those of grapes of corresponding moisture concentration. Predictive models of the dieletric properties as functions of moisture content and temperature were generated using response surface methodology. The results are useful in estimating the volumetric heating of grapes by microwave energy, and these methods can be extended to sugar-based foods in general.

Electrochemistry↗
PubMed1994

Phosphatidylinositol-anchored molecules and inducible lipopolysaccharide binding sites of human and mouse bone marrow cells.

We have previously established that lipopolysaccharide (LPS) induces the expression of new specific LPS-binding sites (LpsR) in mouse bone marrow cells (BMC). We now show that exposure of human BMC to LPS elicits the production of both CD14 molecules (detectable with monoclonal antibody My4) and LpsR (detectable with fluorescein isothiocyanate-LPS). Pretreatment of stimulated human BMC with My4 inhibited the binding of fluorescein isothiocyanate-LPS. The stimulation of human BMC, but not mouse BMC, required the presence of serum. Other characteristics of mouse and human BMC examined were very similar. Their inducible LpsR interacted with the lipid moieties of LPS and Leishmania donovani lipophosphoglycan and with a soluble preparation of peptidoglycan. Moreover, mouse and human LpsR were susceptible to treatment with a phosphatidylinositol-specific phospholipase C (PI-PLC), thus suggesting that both are PI-anchored CD14 molecules. Neither LpsR appeared able to interact with a synthetic LPS antagonist (compound PPDm2) structurally related to the lipid region of LPS. However, PPDm2 blocked LPS-induced expression of LpsR in both BMC. Furthermore, in both species, pretreatment of BMC with PI-PLC did not prevent the cells from expressing LpsR in response to LPS. The results support the hypothesis that the elicited LpsR of mouse and human BMC is an inducible form of CD14, whereas the putative "signaling LPS receptor" of these cells is not CD14 or any other PI-anchored molecule.

Acute-Phase Proteins↗
PubMed1993

Lipopolysaccharide and tumor necrosis factor-alpha induce lipopolysaccharide receptor expression on bone marrow cells by different mechanisms.

Two cell types, monocytes/macrophages and neutrophilic granulocytes, play a prominent role in the pathogenic effects of endotoxins during Gram-negative infections. We previously established that nanomolar concentrations of LPS induce the expression of new specific LPS-binding sites (LpsR) in bone marrow granulocytes of LPS-responsive mice. To examine this induction process further, we asked whether it, like other LPS activities, can be mediated by TNF-alpha. We report that exogenous rTNF-alpha can induce LpsR expression in bone marrow cells (BMC) from both LPS-responsive (C3H/HeOU) and LPS-hyporesponsive (C3H/HeJ) mice. In BMC, LPS elicited a down-regulation of the TNF-alpha receptors (TNF-R) without direct binding to TNF-R. On the other hand, taxol, a microtubule stabilizer that has shown LPS mimetic activity in macrophages, was unable to elicit LpsR expression or induce TNF-R down-regulation in BMC. Thus, unlike the LPS-signaling receptor of macrophages, that of BMC is apparently not functionally associated with microtubules. The LPS-induced expression of LpsR was inhibited only partially with an anti-TNF-alpha serum, and with dexamethasone, suggesting that an autocrine activity of endogenous TNF-alpha cannot alone account for the LPS effect. Comparative analyses also indicated that dexamethasone inhibited the LPS-induced increase of LpsR, but enhanced the number of TNF-induced LpsR+ BMC. Furthermore, the synthetic lipid PPDm2 (a 1,4-bisphosphorylated and N,N-diacylated derivative of 2,3-diamino-2,3-dideoxy-D-glucose) inhibited LPS-induced, but not TNF-induced, expression of LpsR. These data show that in BMC, LPS and TNF-alpha induce LpsR expression by different mechanisms.

Animals↗
PubMed1993

Endotoxin-induced expression of endotoxin binding sites on murine bone marrow cells.

A variety of binding sites for endotoxin (LPS) have been identified on leukocytes. However, the sequence of expression of these receptors, and their interrelations, are poorly understood. In this report, we show that in LPS-responsive hosts, interaction of nanomolar concentrations of LPS with bone marrow cells induces the expression of new specific LPS-binding sites. Cells from LPS-nonresponsive (C3H/HeJ) mice do not express these receptors after LPS treatment. Experimental differences in the conditions allowing the induction and the detection of these binding sites (influence of Leishmania lipophosphoglycan, role of serum), support the hypothesis that interaction of LPS with primary receptors on bone marrow cells triggers the expression of secondary LPS receptors, and that the two types of receptors have distinct fine specificities.

Animals↗
PubMed1993

A synthetic analog of the 3-deoxy-D-manno-2-octulosonic acid disaccharide moiety of rough-type endotoxins does not bind to mouse peritoneal macrophages and human monocytes.

Strong evidence supports the concept that lipid A is the main biologically active region of endotoxins and is recognized by specific binding sites of different cell types. However, receptors for carbohydrates are also present on mononuclear phagocytes, and it has been suggested that one of these lectin-like proteins may be specific for the 3-deoxy-D-manno-2-octolosonic acid (Kdo) residues of endotoxins. To reexamine this hypothesis, we prepared a 125I-labeled conjugate consisting of a synthetic Kdo-2,4-Kdo disaccharide covalently linked to bovine serum albumin (125I-Kdo2-BSA). The Kdo disaccharide residues of this radiolabeled conjugate were fully accessible to a monoclonal antibody which reacts specifically with this epitope. However, 125I-Kdo2-BSA did not exhibit any detectable specific binding on thioglycolate-elicited mouse peritoneal macrophages or on human monocytes. Furthermore, the specific binding of biotin-labeled lipopolysaccharide derivatives to mouse macrophages and human monocytes was not inhibited by a soluble synthetic Kdo-2,4-Kdo-polyacrylamide copolymer or by a synthetic glycolipid consisting of an alpha-Kdo residue glycosidically linked to O-6 of allyl-4-O-phosphoryl-N-3-hydroxytetradecanoyl-beta-D-glucosaminide. These results indicate that binding sites specific for Kdo are not present (or not accessible) on the surface of mouse macrophages and human monocytes.

Animals↗
PubMed1992

Preparation and binding specificity of a monoclonal antibody recognizing 3-deoxy-D-manno-2-octulosonic acid (Kdo) in lipopolysaccharides of Re chemotype.

A mouse monoclonal antibody (MAb E1) was raised against the lipopolysaccharide (LPS) of the Re mutant R595 of Salmonella minnesota. This IgG3 antibody (MAb E1), unstable at low pH and low ionic strength, was purified by chromatography on QAE Sepharose A50. The binding specificity of MAb E1 was characterized by direct and inhibition enzyme immunoassays, using natural LPSs from different strains and chemotypes, and synthetic analogs of LPS substructure of the 3-deoxy-D-manno-2-octulosonic acid (Kdo) and Lipid A regions. Among various LPSs, MAb E1 reacted exclusively with those of Re-chemotype. It recognized alpha-Kdo- monosaccharide and disaccharide structures present as non-reducing side chains in various Re-type LPSs and synthetic antigens. The antibody did not react with Lipid A or various lipids, and the presence of the lipid region was not necessary for the reaction. The recognition of the epitope was not reduced by the presence of a substituent at O-8 of one of the two Kdo units present in the Re LPS from Proteus mirabilis, but the reaction was inhibited by phosphorylation of O-4 of Kdo, by the proximity of core (heptose) or Lipid A (acylated glucosamine) residues, or by certain LPS-LPS interactions.

Animals↗
PubMed1992

New synthetic analogs of lipid A as lipopolysaccharide agonists or antagonists of B lymphocyte activation.

We have studied the ability of synthetic analogs of lipid A to mimic lipopolysaccharide (LPS) for activation of 70Z/3 pre-B cells (expression of surface Igs) or to antagonize this effect. The results indicate that the presence of glucosamine (mono- or disaccharide) as a 'backbone' for the attachment of fatty acids is not necessary for activation of cells of the B lineage. Phosphate groups are not necessary either. Other structural features such as the configuration of particular asymmetric carbons, and the distance between an anionic group and an N-acyl chain, seem to be much more critical parameters for activation of B cells. Among the synthetic lipids which were unable to activate 70Z/3 cells, one compound, consisting of N,N-acylated and bisphosphorylated 2,3-dideoxy-2,3-diamino-D-glucose, behaved as a specific LPS antagonist and blocked also the activation triggered by the other synthetic inducers. The influence of the synthetic lipids on the entry of mature mouse B lymphocytes into the G1A phase of the cell cycle (cell enlargement) was also investigated. A high correlation was observed between the potency to activate pre-B cells and the ability to induce blast formation in mature B cells.

Animals↗
PubMed1992

Otitis media, language development, and parental verbal stimulation.

Examined the impact of recurrent otitis media in the first 3 years of life on verbal abilities of 3- to 4-year-old children and the potential for parental verbal stimulation to buffer the negative effects of intermittent hearing loss. Fathers and mothers of 56 children with variable histories of otitis media participated in videotaped parent-child interactions that were used to code level of parental verbal stimulation. Measures of the children's verbal abilities were the McCarthy Verbal Scale Index and a score for the child's verbalizations with each parent. Active and engaging parental verbalizations appeared to buffer the child's developing verbal abilities from the deleterious effects of recurrent otitis. Post hoc analyses examined the implications of task structure and parent sex on parent verbal stimulation. Discussion addresses the importance of paternal involvement for the home language environment and implications for intervention.

Age Factors↗
PubMed1990

Prosomatostatin II processing is initiated in the trans-Golgi network of anglerfish pancreatic cells.

Anglerfish prosomatostatin II, the precursor of somatostatin-28 II, is produced in different cells from prosomatostatin I, by a cleavage at Arg73. Antibodies were raised against the carboxy-terminal [64-72] portion of the precursor II upstream from somatostatin-28 II sequence. These antibodies recognized only this epitope when unmasked from the entire precursor, allowing the detection of the [1-72] domain which was isolated from pancreatic islets extracts. The antibodies were used to monitor the peptide bond cleavage occurring at the carboxy terminus of Arg73 to generate somatostatin-28 II. Immunocytochemistry revealed labeling both in the vesicles budding from the trans-Golgi network and in the dense core granules. Together, these data support the conclusions that i) prohormone processing is initiated in the Golgi apparatus of the pancreatic islet cells; ii) the "non-hormonal" [1-72] amino-terminal domain of the precursor may be involved in some intra and/or extra-cellular function(s).

Animals↗
PubMed1990

Specific binding of lipopolysaccharides to mouse macrophages--II. Involvement of distinct lipid a substructures.

The interaction of lipopolysaccharide-binding sites of mouse macrophages with the Lipid A region of endotoxins (LPS) was demonstrated by direct binding of labeled Lipid A conjugates, by inhibition of the binding of labeled LPS with anti-Lipid A monoclonal antibodies, and by the considerable reduction of this binding after chemical and enzymatic removal of the fatty acid esters of the LPS. The substructures of Lipid A required for the specific binding of LPS to macrophages were analyzed by the use of synthetic lipids consisting of mono- or disaccharide derivatives of glucosamine. The two phosphate groups of Lipid A (at positions 1 and 4') as well as certain hydroxyl groups, appeared to play a critical role in the binding. However, the reactivities of the synthetic lipids with the macrophage surface, as compared with those with anti-Lipid A antibodies, could hardly be explained by the existence of a single LPS receptor, and suggested the presence, on the macrophage surface, of different LPS-binding sites that recognize different substructures or spatial configurations of the lipid moiety of endotoxins.

Animals↗
PubMed1990

The splenic pool of mouse stem cells: in vitro differentiation and expression of the BP-1 alloantigen on cells of the lymphoid and myeloid lineages.

The relative paucity of data about the development of the stem cell pool present in the spleen prompted this study. During in vitro cultures of B-enriched lymphocytes from mouse spleens and in the presence of a culture supernatant of WEHI-3 cells (WEHI-SUP), a population of cells expressing the BP-1 antigen appears progressively, reaches an optimal size 8 days after initiation of the culture, and disappears on day 28. In 8-day-old cultures, a minor population of cells bearing both BP-1 and B220 can be detected. The growth of this cell population, with characteristics of the B lymphoid lineage (pro-B), is strictly dependent on the presence of WEHI-SUP in the medium. After 2 weeks of culture, the BP-1 antigen is expressed on a cell population, which is essentially constituted of B220-, polynuclear cells. The BP-1 antigen, which is considered as characteristic of early cells of the B lymphoid lineage, can therefore also be expressed on cells of the myeloid lineage. The injection of BP-1+ or B220+ cells in irradiated mice can hardly reconstitute their B cell pool, whereas BP-1- and B220- cells are much more efficient in vivo progenitors of this cell lineage.

Animals↗
PubMed1990

Dual or single infection of the terrestrial snail Solatopupa similis (Bruguière, 1792) with two protostrongylid nematodes, Muellerius capillaris (Mueller, 1889) and Neostrongylus linearis (Marotel, 1913).

The land snails Solatopupa similis were experimentally infected with two protostrongylidae, Muellerius capillaris and Neostrongylus linearis. Although the apparent rate of penetration was always high (64-91%), infection remained low (less than 3 larvae/snail); most of the larvae that penetrated the snails did not develop into second stage larvae. Rates of snail mortality recorded in infected groups were higher than those observed in non infected snails.

Animals↗
PubMed1989

Effects of lipopolysaccharide on macrophages analyzed with anti-lipid A monoclonal antibodies and polymyxin B.

Six monoclonal antibodies (mAb) to the lipid A region of bacterial lipopolysaccharide (LPS), obtained from mice immunized with lipid A-coated Bordetella pertussis cells (mAb 3.E8, 2.21, 2.37, 2.41) or with lipid A covalently coupled to keyhole limpet hemocyanin (mAb R1 and R7), were examined for their potential to inhibit in vitro activities of LPS on macrophages. mAb R7 was inactive in vitro, but the five other mAb inhibited efficiently some in vitro activities of LPS. mAb R1, 2.21 and 3.E8 reduced the LPS-induced secretion of tumor necrosis factor (TNF) and interleukin 1 (IL 1) by macrophages, but did not modify the binding of LPS to macrophages. On the other hand, mAb 2.37 and 2.41 reduced LPS binding to macrophages and subsequent IL1 secretion, but did not modify TNF production. This is in agreement with our previous finding that IL1 and TNF productions can be selectively triggered by synthetic analogs of lipid A substructures (Lasfargues and Chaby, Cell. Immunol. 1988. 115: 165). The pattern of in vitro inhibition of LPS activities (LPS binding to macrophages and production of TNF and membrane IL 1) by polymyxin B was different from those of the two groups of anti-lipid A mAb mentioned above. These observations suggest the presence on lipid A of four functionally distinct substructures.

Animals↗
PubMed1989

The effect of the 1979 French seat-belt law on the nature and severity of injuries to front-seat occupants.

In a regional study of the effect of the 1979 French seat-belt law, the nature and severity of car occupants' injuries were recorded for all car crashes during the same 3-month period in 1976, 1977, 1978 (before the law), and in 1979 (after the law). A trend analysis of data from all 4 years showed a slight decrease in the total injury rate, and significant decreases in the frequency of hospital admissions, and of head, face, arm, and leg injuries. Moderate pelvic and leg injuries, and serious head injuries were also less than expected in 1979. There was also a significant increase in the frequency of thoraco-lumbar spine injuries and of serious cervical spine injuries, but the absolute increase in these injuries was less than the absolute decrease in other injuries. These changes are compatible with the biomechanical effects of increased seat belt use, and thus suggest a beneficial effect of the law.

Accidents, Traffic↗
PubMed1988

Opposite effects of lipopolysaccharide and dextran sulfate on membrane phospholipid metabolism of murine B lymphocytes.

The metabolism of [3H]inositol- and [14C]arachidonate-labeled phospholipids of B lymphocytes from normal (C3H/HePAS) and endotoxin-hyporesponsive (C3H/HeJ) mice, after incubation with two B cell mitogens, lipopolysaccharide (LPS) and dextran sulfate (DxS) was examined. The early effects of the two mitogens on the biosynthesis of phosphoinositides were different. DxS enhanced the levels of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate in C3H/HeJ and C3H/HePAS cells, whereas LPS did not modify the levels of these components. When mixed with DxS, LPS reduced the effects of this stimulant. Analysis of the metabolism of fatty acids gave opposite results. Incorporation of arachidonate in all phospholipids, and particularly in phosphatidic acid, was inhibited in the two cell types after incubation with DxS, but was enhanced in C3H/HePAS and remained unchanged in C3H/HeJ cells after incubation with LPS. This activation of acyltransferases by LPS in B lymphocytes from endotoxin-responsive mice was inhibited when DxS was added in the stimulating mixture. The outcome of these opposite biochemical effects of LPS and DxS on the mitogenic responses of B cells was also examined. Preincubation with DxS for a 15-min period blocked the mitogenic effect of LPS in C3H/HePAS cells, whereas preincubation with LPS blocked the mitogenic effect of DxS in C3H/HeJ cells. Early changes in phospholipid metabolism induced by the two stimulants are therefore correlated with their late mitogenic effect.

Animals↗