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P Poindron

Publications and source records attributed to P Poindron.

At least 73 records · Page 4Linked to original sources
PubMed1994

Establishment of maternal bonding and its mediation by vaginocervical stimulation in goats.

To investigate the establishment of offspring recognition in mother goats, 11 females were subjected to two successive 5-min tests with their own kid and an alien, 2 h 30 min postpartum. All mothers accepted their own kid, while nine rejected the alien. This suggests that in goats, 2.5 h are sufficient for the development of an exclusive bond with the kid. We also studied the role of physiological factors mediating maternal bonding in this species. Eight of the nine goats that rejected alien kids were, therefore, submitted to 5 min of vaginocervical stimulation (VCS) immediately following the selectivity tests. Of these eight goats, five changed their behavior after VCS and accepted the alien kid (0/8 before VCS vs. 5/8 after VCS, p = 0.031). Thus, VCS appears to reduce rejection behavior towards alien kids while resulting in a significant increase in their rate of acceptance. Underlying physiological mechanisms by which VCS may act are discussed.

Animals↗
PubMed1994

Olfaction mediates the establishment of selective bonding in goats.

Nine pregnant goats of the Creole breed were rendered anosmic 3 weeks before parturition by irrigating their olfactory mucosa with zinc sulfate, and nine additional pregnant goats were left intact. At parturition, interactions between all females and their young were observed for 1 h. No differences were found in mother-young relationships between intact and anosmic mothers during this time, except that kids from anosmic females were slower to suck than controls. After 4 h of uninterrupted mother-young, mothers underwent three successive 5-min tests in a predetermined order to study selective bonding: with their own kid, an alien kid of similar coat color and pattern, and an alien kid of dissimilar coat color and pattern. Intact goats readily discriminated between kids, and rejected the two aliens while accepting their own. By contrast, anosmic mothers showed no signs of discrimination and accepted the three types of kids. It is concluded that during the first postpartum hours of contact, mother goats memorize individual olfactory characteristics of their kid that serve as a basis for selective suckling and exclusive bonding. Furthermore, at this early stage, visual characteristics of the young do not appear able to compensate for the loss of olfactory cues.

Animals↗
PubMed1994

Functional beta-glucan receptor expression by a microglial cell line.

In the central nervous system, the functions of microglia appear crucial after brain damage, when phagocytes eliminate cell debris, acting as the scavengers of the brain. Diseases where an active role for microglia has been proposed recently include Alzheimer's disease, the acquired immune deficiency syndrome (AIDS) and multiple sclerosis. Only recently has it been possible to obtain a microglial cell line retaining morphological and functional aspects of these cells and their secretory products. Sugar receptors are expressed by a variety of phagocytes in primary cultures, but in contrast, are absent on the majority of the described macrophage-like cell lines. We here establish, by 4 degrees C binding experiments, that this murine cell line, called BV-2, expresses a high level (9.86 +/- 0.91 x 10(5); n = 3) of beta-glucan receptors. At 37 degrees C, BV-2 cells show high phagocytic power that can only be inhibited by the free polysugar beta-laminarin (a poly-glucose) and not by mannan (a poly-mannose) as described for macrophages. The beta-glucan receptor expressed by the microglial cell line BV-2 is fully functional in phagocytosis of unopsonized heat-killed yeast particles.

Animals↗
PubMed1994

Antitumoral potential of aerosolized interferon-gamma in mice bearing lung metastases.

Cytokines and immune cells are likely to be involved in the control of lung metastasis. We have therefore investigated the possibility of inhibiting lung metastases by the means of interferon-gamma (IFN-gamma) aerosolizations in a murine model of lung cancer. A Lewis lung carcinoma (3LL) was inoculated in the thigh of C57BL/6 mice. Randomized groups of 10 mice each were then treated by repeated aerosols of IFN-gamma (4,000 U/mouse) of aerosols of a Hanks' solution as controls. When the animals were killed at 18 days, the number of lung metastatic nodules was significantly reduced (by 50%; P < 0.01) after IFN-gamma aerosols, compared with controls. When the primary tumor was resected at 18 days and aerosols were continued, in the absence of local recurrence, mice treated by IFN-gamma aerosols survived longer than did controls (P < 0.05). In vitro, IFN-gamma exerted no direct antitumoral effect on 3LL cells in culture. Macrophages recovered from mice receiving IFN-gamma aerosols showed a higher antiproliferative effect on 3LL cells in vitro than did controls. Nevertheless, the higher antiproliferative effect of activated macrophages seems insufficient to explain the difference of survival that we observed between IFN-gamma-treated mice and controls.

Administration, Inhalation↗
PubMed1993

Prednisolone enhances myogenesis and dystrophin-related protein in skeletal muscle cell cultures from mdx mouse.

The differentiation of skeletal muscle cells from mdx mice which lack dystrophin expression was examined after glucocorticoid treatment, namely alpha-methylprednisolone (PDN). Primary skeletal muscle cell cultures were established from newborn mdx, congenic C57BL/10, and allogenic BALB/C mice. We show that PDN promotes the myogenesis of both mdx- and control mice-derived cultures as determined by 1) the number of myotubes, 2) acetylcholine receptors, and 3) dystrophin and dystrophin-related protein levels. These results support the hypothesis that PDN could enhance the myogenesis of satellite cells and increase dystrophin-related protein expression in DMD treated patients.

Animals↗
PubMed1993

alpha-Methylprednisolone promotes skeletal myogenesis in dystrophin-deficient and control mouse cultures.

We have examined the influence of the glucocorticoid alpha-methylprednisolone (PDN) on the morphological differentiation of skeletal muscle cells derived from dystrophin-deficient C57BL/10 mdx, congenic C57BL/10 and allogenic Balb/c newborn mice. We show that PDN enhances myogenic cell numbers in dystrophin-deficient cultures as well as in matched controls. A parallel increase in the fusion rate of myoblasts into myotubes occurs while the size of myotubes, as determined by nuclei per myotube, is slightly increased. This promoting effect of PDN on myogenesis could be related to the enhanced muscular function observed in PDN-treated Duchenne's muscular dystrophy-affected boys.

Animals↗
PubMed1993

Both mannose and beta-glucan receptors are involved in phagocytosis of unopsonized, heat-killed Saccharomyces cerevisiae by murine macrophages.

We studied the involvement of lectin-like receptors in phagocytosis of unopsonized heat-killed yeast (Saccharomyces cerevisiae) by murine macrophage-like cell lines and murine peritoneal resident macrophages. For this purpose we used a technique that allowed us to discriminate ingested and adsorbed heat-killed yeast. The internalization can be partly inhibited by soluble polyosides such as laminarin (beta-glucan) or alpha-mannan. However, when they were used together (0.4 mg/ml alpha-mannan and 0.4 mg/ml laminarin), almost complete inhibition of phagocytosis was obtained. These observations suggest that phagocytosis of unopsonized heat-killed yeast by murine macrophage-like cell lines as well as murine peritoneal resident macrophages is mediated by both mannose and beta-glucan receptors. The respective activity of these two types of receptors is a function of in vitro cell differentiation. To achieve maximal phagocytosis of unopsonized heat-killed yeast, coexpression of both mannose and beta-glucan receptors is required.

Animals↗
PubMed1993

alpha-Bungarotoxin sensitization in experimental autoimmune myasthenia gravis.

A mouse model of MG, termed experimental autoimmune myasthenia gravis (EAMG), can be obtained after immunization with Torpedo acetylcholine receptor (AChR). Although many studies have detailed the consequence of AChR antibodies binding at the neuromuscular junction and the difficulty in obtaining obvious clinical signs, less attention has been focused on the possibility of amplifying the muscular block in order to discriminate between immunized and healthy animals. In the present studies we observe that a single inoculation of alpha-bungarotoxin (alpha-bgt) can amplify the neuromuscular block revealed by repetitive nerve stimulation, and induce in EAMG mice a stable muscular weakness state lasting for at least 169 hours instead of 95 hours in normal mice. This model could provide an excellent tool for evaluating drugs active on neuromuscular transmission.

Animals↗
PubMed1993

A rapid preparation of primary cultures of mouse skeletal muscle cells.

We describe a rapid and reproducible technique for establishing primary cultures of skeletal muscle cells from mouse origin. This method was aimed at avoiding extensive enzymatic proteolysis which is commonly used for preparation of primary skeletal muscle cultures. It relies on a Stomacher blender that allows a rapid and regular mechanical dissociation of muscle samples by repeated shocks. Cultures have been compared to those obtained by a modification of the method of Yaffé (1993) based on tryptic dissociation of rat muscle thighs. The time of preparation was reduced to 1 h and 15 min as compared to 4 h with the technique of Yaffé. Both cultures displayed similar morphologies and exhibited comparable myogenesis processes. Cellular yield, rate of myotube formation and myotube numbers were similar. The expression of myogenesis markers were identical as assessed by determination of acetylcholine receptor number, creatine kinase activity and level of myosin light chain.

Animals↗
PubMed1993

Failure to obtain hybridomas between human macrophages and human tumoral U-937 cells is probably due to parental macrophages.

Despite more than 50 attempts and the use of various methods, it has been impossible to establish homologous hybridomas between human mature macrophages and 8-azaguanine-resistant U-937 clones prepared in the laboratory. To rule out the possibility that these clones were unsuitable for the selection of hybrids, a study of their properties was done. It was shown that U-937 wild type cells were able to produce HPRT, whereas 8-azaguanine (8-aza)-resistant clones did not. Curiously, exonic and intronic HPRT sequences were undetectable both in wild type and in 8-aza-resistant cell genomes, under conditions where they were detected in control cells. Chromosome analysis of the clone UM9, one of the most frequently used in fusion experiments, revealed many qualitative and quantitative differences with the U-937 wild type cells. 8-aza-resistant U-937 cells were capable of fusion with human macrophages and gave rise to heterokaryons and probably to synkaryons, which survived for weeks without dividing in hypoxanthine-aminopterin-thymidine medium. The results could be interpreted in terms of the existence of a transacting negative regulatory mechanism of the macrophage genome on the proliferative capacity of homospecific hybridomas.

Animals↗
PubMed1993

Effects of Clostridium difficile toxin B on human monocytes and macrophages: possible relationship with cytoskeletal rearrangement.

Toxin B from Clostridium difficile is cytopathic in vitro for various types of cells, including polymorphonuclear cells, lymphocytes, and monocytes. Since intestine lamina propria is rich in macrophages, we studied the effect of toxin B on human monocytes and on human macrophages generated in vitro by long-term culture of purified circulating blood monocytes. Upon addition of toxin B, human monocytes exhibited few modifications whereas macrophages adopted a stellate morphology, with rounding up of the perikaryon. Toxin B made microfilaments of actin disappear and induced an important reorganization of vimentin and a redistribution of tubulin. Membrane area increased by approximately 16%. Toxin B did not affect the viability of human mononuclear phagocytes and did not exert any significant lytic effect. It profoundly altered the phagocytic function of macrophages. When activated by gamma interferon in the presence of toxin B, monocytes were more cytotoxic for U-937 target cells than control monocytes activated in absence of toxin. Finally, the combined treatment of monocytes with gamma interferon and toxin B increased significantly the secretion of tumor necrosis factor alpha, whereas toxin B alone was unable to induce tumor necrosis factor production. These results suggest that morphological and functional alterations induced in human mononuclear phagocytes by toxin B from C. difficile are due to the disorganization of the cytoskeleton and the resulting impairment of the membrane traffic equilibrium.

Bacterial Proteins↗
PubMed1993

[Value of TE671 cells in the detection of anti-acetylcholine receptor antibodies].

The measurement of antibodies directed against the cholinergic receptor, produced by myasthenic patients, involves a radioimmunoassay. The use of human muscular nicotinic cholinergic receptor is highly recommended for this assay. However, difficulties in supplying and standardizing this reagent led us to consider its replacement by the homologous cholinergic receptor constitutively expressed by the human cell line TE671. TE671 cells were grown in mass cultures on microcarriers and acetylcholine receptors were solubilized using detergents. Replacement of human muscular receptor by cellular receptor in the radioimmunoassay assay was assessed by challenging these 2 antigens for numeric or diagnostic correlations. Using TE671 receptor, the correlations observed were good and, despite a slight decrease in the absolute values of the titers, about 90 p. 100 of the assays provided the same diagnostic accuracy. Some interfering proteins, perhaps immature acetylcholine receptor alpha subunits, could be expressed and could account for the slight decline in the antibody titers obtained using TE671 receptor. These interferences could be overcome by a further step of purification and concentration of the various receptor preparations. Finally, TE671 receptor could definitely replace human muscular receptor for screening and measuring myasthenic patients auto-antibodies.

Adolescent↗
PubMed1992

A new and simple method for studying the binding and ingestion steps in the phagocytosis of yeasts.

Autoclaved yeasts are stained light pink by May-Grünwald Giemsa (MGG). If treated with tannic acid solution just before MGG staining, they display a deep violet color. It seemed possible that these properties could be used to discriminate between extra- and intracellular yeasts in a phagocytosis test, extracellular yeasts being violet and intracellular yeasts being pink. To validate this protocol, quantitative studies of phagocytosis by MALU cells (a murine macrophage cell line) were performed in the presence or absence of drugs known to interfere with phagocytosis. After treatment of cells with cytochalasin B, the mean number of pink yeasts per cell decreased in a dose-dependent manner, the mean number of violet yeasts increased in a dose-dependent manner, whereas the total number of cell-associated yeasts remained almost unchanged whatever the dose used. After treatment with alpha-mannans or chloroquine, the mean numbers of both violet and pink yeasts decreased in a dose-dependent manner. These results confirmed that (i) violet yeasts are extracellular, (ii) autoclaved yeasts recognize lectin receptors, and (iii) unstained (pink) yeasts are intracellular. We show that this simple method can be used for quantitative light microscopic analysis of both the attachment and internalization steps in the phagocytosis of yeasts.

Animals↗
PubMed1992

Specific effect of corticoids on acetylcholine receptor expression in rat skeletal muscle cell cultures.

The potential effect of different classes of steroids on the expression of acetylcholine receptors (AChR) was studied in different primary cultures of newborn-rat skeletal muscle cells. Comparison among three techniques for preparing newborn skeletal muscle cells showed that these systems were equivalent to study AChR expression. Only corticoids stimulated myogenesis as a twofold increase in AChR expression indicated. Among the corticoids, the glucocorticoids were the more potent, whereas the mineralocorticoid aldosterone had less marked effect. The sex hormones progesterone and testosterone partially blocked these effects, without inducing any significant effect when given alone. The steroids tested differed in efficacy in correlation with their different chemical structures. Among the glucocorticoids a clear structure-activity relationship could be established. These results emphasize the specificity of corticoid action on muscle cells and suggest an explanation for the effects induced by glucocorticoids used in treating human muscular or neuromuscular diseases.

Adrenal Cortex Hormones↗
PubMed1992

Phenotypic characterization of three long-term-cultured murine resident macrophage lines.

The antigenic phenotypes of three long-term cultured murine resident macrophage lines selected in vitro from cell suspensions of different tissues--namely MAY 1 (from the peritoneal cavity), MASP (from the spleen) and MALU (from lung tissue)--were determined using a panel of monoclonal antibodies. The results indicate that all three cell lines belong to the mononuclear phagocyte system and express characteristics indicating a rather high differentiation state. However, there was a significant difference in antigen expression between the two macrophage lines obtained from solid tissues (MASP from spleen and MALU from lung), which were very similar in their antigenic pattern, and the MAY 1 line obtained from the peritoneal cavity, which seemed to be less well differentiated. The antigenic profile of the "mesothelial" cell population associated with the MASP line indicates that this cell population is difficult to characterize and to include in a particular lineage.

Animals↗
PubMed1992

Intracerebral oxytocin is important for the onset of maternal behavior in inexperienced ewes delivered under peridural anesthesia.

Measurement of cerebrospinal concentrations of oxytocin (OT) in intact and peridural-anesthetized ewes showed that central release of OT during parturition is inhibited by this anesthesia. Also, observations of maternal behavior and attraction to amniotic fluid (AF) in inexperienced peridural-anesthetized parturient ewes after intracerebroventricular injections of either OT (2 x 10 micrograms) or saline showed that OT infusions increased the proportion of maternal females (2/17 vs. 10/20; p = .01) and attraction to AF. This study confirms that in sheep vaginocervical stimulation activates the oxytocinergic system, which induces the onset of maternal behavior, and that this action is not limited to maternally experienced females.

Anesthesia, Epidural↗
PubMed1992

Human interferons-alpha inhibit the production of immunoglobulin M by secreting and nonsecreting lymphoblastoid cell lines.

It is well known that human lymphoblastoid interferon-alpha [HuIFN-alpha(ly)] may either increase or decrease antibody production by B cells, in vivo as well as in vitro, depending on the experimental conditions and the system used. We compare here the effect of HuIFN-alpha(ly) and human recombinant interferon-alpha (rHuIFN-alpha) on immunoglobulin M (IgM) production by secreting and nonsecreting human B-like lymphoblastoid cells, respectively, ST8246, and Daudi cells. Under our experimental conditions, Daudi cells were less sensitive to the antiproliferative effect of IFN than previously reported by other authors, and ST8246 cells were insensitive to this antiproliferative effect. In contrast, IgM production was profoundly affected in both cell lines. Thus, we could discriminate between the effect on cell growth from the effect on the immune response. Using high-pressure liquid chromatography (HPLC) separation, mu chains and monomeric and pentameric IgM were distinguished from cytosolic and membrane-associated fractions and from culture medium (extracellular IgM). Pentameric extracellular IgM and monomeric membrane IgM were diminished by HuIFN-alpha(ly) treatment, respectively, in ST8246 cells and in Daudi cells. We conclude that HuIFN-alpha(ly) induces regression of B-like lymphoblastoid cells toward a less mature phenotype.

Antibody-Producing Cells↗