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J L Mege

Publications and source records attributed to J L Mege.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Function of polynuclear neutrophils in patients with juvenile periodontitis and rapidly progressing periodontitis].

It is generally assumed that early onset forms of periodontal disease (including Juvenile and Rapidly Progressive Periodontitis) are associated with a defect in neutrophil behaviour. We have investigated neutrophil functions in patients with Juvenile (J.P.) and Rapidly Progressive Periodontitis (R.P.P.). In the group of J.P. patients the directed mobility (FMLP and zymosan activated plasma) is significantly decreased. The superoxide generation in response to FMLP decreases while the PMA response is normal. In the group of R.P.P. patients no significant abnormality has been reported.

Aggressive Periodontitis↗
PubMed1990

[Impairment of neutrophil functions: study of a family with a case of juvenile periodontitis].

Neutrophil function was assessed in family in which only one member suffered from Juvenile Periodontitis (JP). Directed mobility (fMet-Leu-Phe and zymosan-activated plasma) was decreased in all siblings without involving a seric inhibitor. Adhesion was studied by a new method which allows for the evaluation of both adhesive rate and binding strengths. The latter parameters were decreased in the parents neutrophils, but remained increased in a set of twin sisters. The specific receptor induced phagocytosis was altered in all members of the family (FC receptor: IgG-SCR, C3b and mannosylfucosyl receptor: zymosan). The superoxide generation in response to fMet-Leu-Phe was decreased while the PMA response was almost normal. These results suggest an overall abnormality of ligand-receptor interactions (C5a, fMet-Leu-Phe, Fc and C4b receptors), this defect seems to involve some membrane characteristics and underlines the absence of correlation between PMN deficiency and the clinical expression of J.P.

Adult↗
PubMed1989

Effect of granulocyte-macrophage colony-stimulating factor on superoxide production in cytoplasts and intact human neutrophils: role of protein kinase and G-proteins.

Granulocyte-macrophage colony-stimulating factor, GM-CSF, potentiates superoxide generation produced by human neutrophils stimulated with fMet-Leu-Phe and platelet-activating factor, PAF, but not by phorbol 12-myristate 13-acetate (PMA) or opsonized zymosan. The potentiation is greatest in fMet-Leu-Phe-stimulated cells. This indicates that the actions of only certain receptors are potentiated by GM-CSF. Incubation of the cells with the protein kinase inhibitor H-7 or with the protein synthesis inhibitor cyclohexamide before the addition of GM-CSF does not affect the observed potentiation. The rationales behind these studies are to examine the roles of protein kinase C and protein synthesis in the action of GM-CSF. The data suggest that neither protein kinase C nor protein synthesis is necessary for GM-CSF action. On the other hand, no potentiation can be seen in the presence of cytochalasin B. Unlike intact cells, GM-CSF does not enhance superoxide production by cytoplasts stimulated with fMet-Leu-Phe. The rationale behind the use of cytoplasts is to examine the role of granules and/or nucleus in GM-CSF action, and the data indicate that one or more of these two components is necessary for the priming effect of GM-CSF. The amount of actin associated with the cytoskeleton under control of fMet-Leu-Phe-stimulated condition is the same in normal and GM-CSF-treated human neutrophils. Botulinum D toxin ADP-ribosylates a protein with a molecular weight of 22 kDa. This ribosylation is reduced in homogenates obtained from cells pretreated with botulinum D toxin or GM-CSF. Botulinum D toxin does not affect the basal or the fMet-Leu-Phe-induced rise in the intracellular concentration of free calcium in human neutrophils. GM-CSF also increases the rise in intracellular concentration of free calcium in human neutrophils stimulated with PAF or fMet-Leu-Phe. The increases are inhibited by pertussis toxin. Several important conclusion can be drawn from these data. 1) GM-CSF potentiates the rise in Ca2+i produced by PAF and fMet-Leu-Phe, and these potentiations are inhibited in pertussis-toxin-treated cells. 2) GM-CSF does not prime cytoplasts to stimulation by fMet-Leu-Phe. This suggests that the granules and/or nucleus are necessary for the priming action. 3) The priming by GM-CSF is not mediated by the H-7-sensitive protein kinase C, botulinum D-sensitive G-protein, or protein synthesis.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Phagocyte-pathogen in the infected host.

Phagocytosis is a major mechanism of defense against bacterial infections. The ingestion of different microorganisms by blood granulocytes or monocytes may involve a variety of cell membrane recognition structures (e.g., immunoglobulin or complement receptors, lectin-like structures or other nonspecific binding sites). It is of interest to know which mechanism plays a prominent role in the management of a particular type of infection. Forty-three pathogenic bacterial suspensions were obtained from patients under mechanical ventilation at the onset of nosocomial lower respiratory tract infections. They were coincubated with blood granulocytes from the same or other patients in the presence or absence of the corresponding serum. Phagocytosis and the oxidative burst were then assayed. We conclude the following: a) Substantial phagocytosis was found under serum-free conditions and the patients' sera did not dramatically enhance bacterial uptake during the first days after the onset of clinical symptoms. b) The phagocytes from an infected patient did not display any peculiar inability to bind to the bacteria that grew successfully in this subject. Hence, the occurrence of a particular infection might be dependent on a defect of intracellular killing of ingested pathogens or on the conditions of infection development.

Adult↗
PubMed1989

Actions of the protease inhibitor phenylmethylsulfonyl fluoride on neutrophil granule enzyme secretion and superoxide production induced by fMet-Leu-Phe and phorbol 12-myristate-13-acetate.

The protease inhibitor, phenylmethylsulfonyl fluoride inhibits granule enzyme release and, above 1 mM, superoxide production from rabbit peritoneal neutrophils induced by the chemotactic peptide, fMet-Leu-Phe. At concentrations below 1 mM, it enhances superoxide production. Superoxide generation stimulated by phorbol 12-myristate-13-acetate is increased by phenylmethylsulfonyl fluoride at all concentrations studied. Phenylmethylsulfonyl fluoride has no effect on the rise in intracellular calcium or the depolarization induced by fMet-Leu-Phe but does decrease the extent of repolarization and abolishes hyperpolarization. It depresses actin polymerization and abolishes cytoplasmic alkalinization caused by fMet-Leu-Phe. The increased phosphorylation induced by phorbol 12-myristate-13-acetate in four of the five proteins studied was not affected by phenylmethylsulfonyl fluoride, but the increased phosphorylation of the fifth, a 21-kD protein was enhanced. We conclude that phenylmethylsulfonyl fluoride acts on inhibitory and enhancing processes or steps induced by fMet-Leu-Phe which are subsequent to or independent of calcium mobilization and protein kinase C activity.

Actins↗
PubMed1988

Effect of botulinum D toxin on neutrophils.

Activated botulinum D toxin ADP-ribosylates a 22 kDa molecular weight protein in homogenates obtained by sonication of a suspension of rabbit peritoneal neutrophils. The ADP-ribosylation catalyzed by activated botulinum D toxin is inhibited in homogenates obtained from cells pretreated with the toxin, suggesting that it is able to enter into these cells and be activated by them. The rise in intracellular concentration of free calcium in toxin treated cells stimulated by fMet-Leu-Phe is similar to that found in control cells. The basal concentration of intracellular free calcium is significantly elevated in neutrophils treated with the intact but not with the activated form of the botulinum D toxin. Superoxide generation in control and native toxin treated cells stimulated with fMet-leu-Phe, phorbol 12-myristate 13-acetate or opsonized zymosan is the same. The release of beta-glucosaminidase produced by fMet-Leu-Phe or Concanavalin A in botulinum D toxin treated neutrophils was slightly higher than the corresponding release in control cells. Furthermore, the fMet-Leu-Phe-induced increase in the amount of actin associated with the cytoskeleton is not inhibited by botulinum D toxin. These results suggest that the 22 kDa protein which can be ADP-ribosylated by botulinum D toxin is not involved in these stimulated neutrophil responses.

Adenosine Diphosphate Ribose↗
PubMed1988

Zymosan but not phorbol myristate acetate induces an oxidative burst in rat bone marrow-derived macrophages.

We found that rat bone marrow-derived macrophages responded to opsonized zymosan by releasing superoxide anion. However, these cells were defective in the response to the potent oxidative burst activator phorbol myristate acetate (PMA). This result was observed whatever the concentration of agonist used and with different concentrations of cells. Since it is strongly suspected that protein kinase C (PKC) is involved in the transductional pathway induced by PMA in numerous cell types, and particularly in phagocytes, we studied PKC and we observed that it was functional in rat bone marrow-derived macrophages, but only present at a low level. Thus, we suggest that our results are consistent with the possibility that zymosan-induced respiratory burst may be independent of PKC and that these cells may not possess the minimal level of PKC required for responding to PMA.

Animals↗
PubMed1988

Myotonic dystrophy: defective oxidative burst of polymorphonuclear leukocytes.

Because myotonic dystrophy (MD) is an autosomal dominant multisystemic disorder affecting plasma membrane, we have studied the oxidative burst of PMNs. The PMA and fMet-Leu-Phe-stimulated superoxide generation is defective in the patient group as compared to controls: the response is both delayed and low. The kinetic parameters of the NADPH oxidase complex are not affected. We have not found any abnormalities in the membrane potential changes. In addition, the cytosolic protein kinase C (PKC) activity of resting PMNs is similar in MD patients and controls, and the translocation of protein kinase C in response to PMA is not impaired. The decrease of the oxidative response of PMNs from MD patients may be related to an abnormality of the environment of the NADPH oxidase.

Adult↗
PubMed1988

Disseminated pustular dermatosis in polycythemia vera. Relationship with neutrophilic dermatosis of myeloproliferative disorders: study of neutrophil function.

An unusual case of disseminated pustular eruption associated with polycythemia vera is described. This eruption can be included in the group of neutrophilic dermatoses of myeloproliferative disorders (pyoderma gangrenosum, Sweet's syndrome). A defect in superoxide anion (O2-) generation is detected. The fact that both the clinical condition and the neutrophil function improved with the use of dapsone suggests that the O2- generation defect may play a role in the pathogenesis of the eruption. From an evolutionary standpoint, the occurrence of a neutrophilic dermatosis in polycythemia vera could be an unfavorable sign of preleukemia.

Aged↗
PubMed1988

Diacylglycerol kinase inhibitor R59022 and stimulated neutrophil responses.

The generation of phosphatidic acid in neutrophils stimulated by the chemotactic factor formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe) is inhibited by the diacylglycerol kinase inhibitor R59022. Superoxide generation produced by fMet-Leu-Phe, leukotriene B4, platelet-activating factor, or phorbol 12-myristate 13-acetate can be greatly increased in neutrophils pretreated with R59022. The potentiation occurs in the presence or absence of cytochalasin B and is evident in the absence of extracellular calcium. In addition, where the superoxide generated by fMet-Leu-Phe is not inhibited by the protein kinase C inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), the increase by R59022 is diminished by this compound. Unlike cytochalasin B, R59022 does not affect the increase in cytoskeletal actin produced by fMet-Leu-Phe or platelet-activating factor nor does it decrease the basal level. Furthermore, the basal intracellular concentration of free calcium, but not the rise produced by fMet-Leu-Phe or platelet-activating factor, is elevated by R59022. The data presented here suggest that the potentiation by R59022 of the oxidative burst is most likely mediated through protein kinase C.

Animals↗
PubMed1987

Quantification of the nonspecific intercellular transfer of fluorescent molecules between labeled and unlabeled rat thymocytes.

Fluorescein isothiocyanate has been used to label normal or tumor cells in order to study their migration in vivo. This requires that any transfer of fluorescence to neighbouring cells be carefully ruled out. The aim of the present report is to demonstrate the possibility of a transfer of fluorescein or fluorescein-bound molecules between untreated and labeled cells. When normal rat thymocytes were co-incubated with labeled cells (about 5 X 10(6) fluorescein molecules/cell) under continuous agitation or exposed to supernatants of these labeled cells, they bound an average of 10(4) fluorescein molecules. When the incubation was done on cell pellets after centrifugation, this transfer was increased tenfold. Hence, intercellular molecular exchange may occur in the absence of any specific interaction.

Animals↗
PubMed1987

Analysis of cell structural and functional diversity by combination of micromanipulation and microfluorimetry.

Fluorescent molecules are widely used to study quantitative cell properties, such as density of different antigenic markers or membrane responses to various stimuli. In most cases, studies are done on bulk cell populations with a spectrofluorimeter or at the single cell level with a cytofluorograph. However, only microspectrofluorimetric techniques allow continuous recording of dynamic events undergone by individual cells. The aim of the present report was twofold: first, to describe a methodology easily accessible to cell biologists that allows simultaneous manipulation of single cells and measurements of their fluorescence properties; and second, through this methodology to study quantitative aspects of cell structure and function such as binding of a fluorescein-labeled lectin, transfer of fluorescent molecules between labeled and unlabeled cells brought in close contact, or fluorescence response of individual cells stimulated after being loaded with a potential-sensitive dye. We conclude that the understanding of many aspects of cell structure and behavior requires that individual cells be studied under dynamic conditions and for prolonged periods of time.

Animals↗
PubMed1987

Use of cell contour analysis to evaluate the affinity between macrophages and glutaraldehyde-treated erythrocytes.

Recently, several authors evaluated the affinity between lipid bilayers or erythrocyte membranes by analyzing the deformation of cells or vesicles they brought into close contact using micromanipulators. In the present report, we extend this approach in a study of the adhesive properties of rough nucleated cells. Rat peritoneal macrophages were made to bind human red cells modified with glutaraldehyde or glutaraldehyde and polylysine. Conjugates were examined with electron microscopy, and photomicrographs were digitized for quantification of cell surface roughness in and out of adhesion areas. Also, macrophages were subjected to micropipette aspiration to find a relationship between apparent surface tension and area increase. Assuming that this increase was a direct consequence of a smoothing of the cell surface on the submicrometer scale, the actual affinity between macrophages and erythrocytes was estimated. The obtained values ranged between 8.4 X 10(-5) and 18.2 X 10(-5) J/m2. It is concluded that cell surface roughness may be an important parameter of cell adhesion and perhaps deformation. This is made amenable to experimental study by the present approach.

Aldehydes↗
PubMed1987

Study of CTL and LAK contacts to target cells after treatment with mitomycin C and adriamycin.

We tried to understand the role of Mitomycin C and Adriamycin in the increased killing of target cells by Cytotoxic T lymphocytes (CTL) and lymphokine activated killers (LAK). For this purpose, we used an objective method allowing quantitative evaluation of the roughness of cell contours on electron micrographs. We compared the folding of the membranes of LAK and CTL as well as conjugated targets exposed to different treatments. We demonstrated first that CTL and LAK displayed similar morphological patterns: the killer cells were more villous than targets in the free areas, and second that the former cells exhibited significant smoothing on the areas of contact with these targets. These results suggest that the binding process (as distinct from the recognition step) is dependent on killer properties which are the same in CTL, LAK and probably NK cells.

Animals↗
PubMed1987

[Physiopathology of the mechanism of activation of neutrophils: a future pathway?].

Numerous agonists such as chemotactic factors, phorbol esters, calcium ionophores, arachidonic acid or particles induce a cascade of events associated to oxygen reduction, the oxidative burst, in phagocytes and specially in neutrophils. Diverse transductional pathways involved in the oxidative burst were described. Moreover, various pathologies of the transductional pathways in different cell systems were recently observed. We think that the study of neutrophils constitutes first an excellent model of Cell Biology and second a putative model of the physiopathology of the transductional pathways.

Acute Disease↗
PubMed1986

Quantification of cell surface roughness; a method for studying cell mechanical and adhesive properties.

The presence on the surface of nucleated cells of a variety of asperities of different size and shape plays a prominent role in cell-cell and cell-substrate interaction. Also, the organization of these asperities is directly related to cellular cytoskeletal elements. In the present report, we describe a simple and objective method of studying electron micrographs to quantify the roughness of cell contours. Constant-length segments of cell boundaries are compared to reference circular segments with common extremities and enclosing the same area. This procedure was performed with a digitizer connected to a microcomputer, and it was used to analyse model contours or electron micrographs of (i) target tumour cells bound by cytotoxic T lymphocytes and (ii) thymocytes sticking to concanavalin A-coated surfaces. It is shown that this method allows precise quantification of cell deformation in adhesive zones, which may allow absolute evaluation of adhesive stimuli.

Animals↗