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E Fontan

Publications and source records attributed to E Fontan.

At least 19 recordsLinked to original sources
PubMed2001

Early translocation of acid-adapted Listeria monocytogenes during enteric infection in TNF/LTalpha-/- mice.

TNF/LTalpha deficient mice are devoid of Peyer's patches and lack mesenteric lymph nodes. Translocation, especially in the early steps after intragastric delivery of Listeria monocytogenes, has been explored in this study, and the role of TNFalpha has been addressed. We showed that L. monocytogenes translocation occurred at least as efficiently in TNF/LTalpha-/- mice as in TNF/LTalpha+/+ littermates. Even very low inocula (2.7x10(4) cfu) could initiate infection in the TNF/LTalpha deficient mice. Early kinetics of dissemination to the spleen and liver were similar, L. monocytogenes reaching these organs at 8 h post inoculation. However, a 10-fold higher bacterial load was observed at this early time point in the TNF/LTalpha deficient mice. rTNF pretreatment (4 h before intragastric inoculation) had no effect on the L. monocytogenes associated with the caecum-colon walls at 10 h after inoculation, although bacterial levels in the caecum-colon lumen and in spleen and liver were already controlled.

Animals↗
PubMed2001

Characterisation of a Listeria monocytogenes mutant deficient in D-arabitol fermentation.

We selected and analysed a Tn917-lac Listeria monocytogenes mutant deficient in D-arabitol fermentation. Comparison of the 310-aa-long translated partial sequence of the disrupted gene with known proteins showed similarity with the phosphotransferase system galactitol-specific enzyme IIC component of the alkaliphilic Bacillus halodurans (50% identity) and of Escherichia coli (36% identity). Fermentation of 18 other carbohydrates was unimpaired, suggesting the specificity of this transmembrane permease IIC for the pentitol D-arabitol. The deficiency in D-arabitol fermentation did not alter L. monocytogenes virulence in the BALB/c mouse model after intravenous and intragastric inoculations. This fully virulent mutant is a valuable tool to study L. monocytogenes oral infection, since the antibiotic resistance marker present on the Tn917-lac transposon will efficiently select L. monocytogenes against the intestinal microflora.

Animals↗
PubMed2000

Effect of acid-adaptation on Listeria monocytogenes survival and translocation in a murine intragastric infection model.

Acid tolerance response mechanisms can greatly influence Listeria monocytogenes survival in low pH foods. In the present paper, the effect of acid-adaptation together with control of gastric pH level on L. monocytogenes survival and translocation was analyzed after intragastric inoculation in the BALB/c mouse model. Our results showed that acid-adaptation led to an increase in resistance to the first barrier constituted by the low gastric pH and that inoculation at alkaline pH had a synergistic effect. It resulted in a higher live bacterial load reaching the next intestinal compartments and was correlated with increased translocation rates to the mesenteric lymph nodes, both at the frequency and quantitative levels. Our results in this murine model suggest that acid-adaptation of L. monocytogenes in low pH foods, together with control of gastric pH level through dietary practices, or use of inhibitors of gastric acid secretion, may be potential aggravating risk factors to food-borne listeriosis.

Adaptation, Physiological↗
PubMed1997

The anti-tumoral activity of human glycoprotein HGP.92: a study with the mouse Lewis-lung-tumor cell.

The ability of a purified human glycoprotein (HGP.92) to exert anti-tumor activity was investigated in a mouse model using long-term readout assays. In vitro, in the presence of inflammatory mouse macrophages incubated with HGP.92, the growth of the mouse Lewis-lung-tumor cells (3LL) was decreased. This effect was concentration-dependent and required direct contact between tumor targets and HGP.92-treated macrophages. In addition, if the macrophage monolayer was depleted of HGP.92 before addition of the target cells, no more cytostatic effect was observed. This anti-tumor activity of HGP.92-treated mouse macrophage was partially abrogated by addition of catalase in the culture medium, but not by superoxide dismutase or scavengers of the hydroxyl radical and singlet oxygen. Moreover, this tumor-cell growth reduction was not dependent on nitric oxide. In vivo, multiple i.v. injections of HGP.92 (5 times, 3 days apart) during the first week and a half exerted significant anti-tumor activity, as assessed by the reduction of both the number and the size of the lung nodules 3 weeks after i.v. inoculation of 3LL cells.

Adjuvants, Immunologic↗
PubMed1995

Purification of a 92 kDa human immunostimulating glycoprotein obtained from the Tamm-Horsfall glycoprotein.

A purification method for a human urinary glycoprotein (HGP92) dissociated from Tamm Horsfall protein (THP) is described. Tamm-Horsfall protein, obtained by salt precipitations, was again precipitated in presence of monovalent ions. In these conditions, Tamm-Horsfall protein displayed a tendency to form a gel. After ultracentrifugation, HGP92, which was trapped in the gel, was dissociated from Tamm-Horsfall protein and found in the supernatant. The final step of purification of HGP92 was chromatography on a DEAE Affigel blue column. Injected intravenously, HGP92, but not THP, protected mice against a lethal inoculum of Listeria monocytogenes. This procedure has the advantage of being easy to perform, and enables preparation of large amounts of HGP92. These results suggest that the previously described 'immunostimulating' properties of Tamm-Horsfall protein were, in fact, a consequence of its contamination by HGP92.

Adjuvants, Immunologic↗
PubMed1995

Human glycoprotein HGP92 induces cytokine synthesis in mouse mononuclear phagocytes.

HGP92 has been shown to enhance in vitro and in vivo the bactericidal and tumoricidal activity of mouse macrophages. In this study we investigated the effect of HGP92 on the accumulation of cytokine mRNA in mouse inflammatory, peritoneal macrophages and the monocytic cell line J774. HGP92 significantly enhanced the level of cytokine mRNA for IL-1 alpha, IL-1 beta, IL-6, IL-10, IL-12, TNF-alpha and GM-CSF during the first 24 h of the incubation. This effect triggered by HGP92 was comparable to that obtained with lipopolysaccharide (LPS), which is a strong cytokine inducer. This accumulation of cytokine mRNA in macrophages was correlated with secretion of IL-6 and TNF-alpha in cell supernatant. The release of IL-6 was HGP92 concentration dependent over a range of 0.3-10 micrograms/ml with a maximum production obtained after a 24 h incubation of inflammatory macrophages with HGP92. This effect was shown not to be due to contamination of HGP92 by LPS since inflammatory macrophages from C57BL/6 mice were responsive to HGP92 pretreated with polymyxin B sulfate and unresponsive to heated HGP92. Stimulating activity of HGP92 was confirmed using macrophages from C3H/HeJ mice. These results suggest that HGP92 might modulate the immune responses by increasing cytokine production by macrophages.

Adjuvants, Immunologic↗
PubMed1994

A 92-kDa human immunostimulatory protein.

We purified to apparent homogeneity a human urinary glycoprotein of 92 kDa (HGP.92) that, administered intravenously at 250 micrograms/kg, fully protected mice against a lethal inoculum of Listeria monocytogenes. Since HGP.92 protected scid mice, which lack B and T lymphocytes, this increased resistance to Listeria did not appear to be lymphocyte mediated. Furthermore, inflammatory macrophages incubated with 6 nM HGP.92 inhibited the growth of Lewis carcinoma cells in vitro. These two activities appeared to depend on an oligosaccharide moiety, as they were lost after N-Glycanase treatment of HGP.92. Thus, the biological activity of HGP.92 was in some way related to a glycan moiety.

Amino Acid Sequence↗
PubMed1993

Macrophage-induced cytotoxicity and anti-metastatic activity of a 43-kDa human urinary protein against the Lewis tumor.

Resident, inflammatory or bone-marrow macrophages from C57Bl/6 mice incubated in vitro with a pure human urinary protein (HGP.43) decreased the growth rate of Lewis tumor cells (3LL). This inhibition of 3LL growth was the result of a cytotoxic activity of these macrophages which was independent of oxygen metabolites and nitrous oxide. Murine monoclonal antibodies (MAbs) against HGP.43 inhibited macrophage-mediated cytotoxicity. This cytotoxic activity was not due to the release of cytotoxic factors in the culture supernatant, showing that a contact between macrophages and tumor cells was required to express cytotoxicity. The presence of HGP.43 was absolutely necessary during the incubation of macrophages with target cells. In vivo, in HGP.43-treated mice, the growth of the primary tumor was not delayed but the size and number of lung metastases were significantly reduced 21 days after tumor inoculation.

Animals↗
PubMed1992

Immunostimulatory human urinary protein.

We have previously extracted a protein from inflammatory mouse granuloma that fully protects normal mice against lethal Listeria monocytogenes infection. We now report that polyclonal antibodies directed against this protein react with a human urinary fraction that also provides full protection of normal mice against L. monocytogenes. Murine monoclonal antibodies completely inhibit the protective activity of the human urinary fraction. We have purified to apparent homogeneity a human glycoprotein of 43 kDa (HGP.43), pI = 3.2 +/- 0.2. HGP.43 injected i.v. at 250 micrograms/kg fully protected mice against a lethal inoculum of L. monocytogenes. Such resistance followed injection of HGP.43, 4 days before and, still significantly, 8 hr after Listeria infection. In scid mice lacking T and B cells, similar resistance to L. monocytogenes was observed. Inflammatory murine macrophages became cytostatic against Lewis carcinoma cells after incubation with 1.5 nM HGP-43.

Animals↗
PubMed1988

Inflammation and anti-tumor resistance. IV. Induction of cytostatic activity of murine peritoneal cells by a mouse granuloma protein.

Peritoneal cells from C57B1/6 mice, incubated in vitro with a pure mouse granuloma protein (MGP), decreased growth of Lewis tumor cells (3LL). This cytostatic activity was due to the release of stable cytostatic factor(s) as determined by reduction of 125iododeoxyuridine (125I-UdR) incorporation in target cell cultures. Resident, inflammatory or bone-marrow-derived macrophages incubated with MGP had no cytostatic effect on tumor cells. Co-operation between lymphocytes and macrophages was required to express cytostasis when these cells were exposed to MGP. Maximal production of this factor by peritoneal cells was detected in the medium after treatment with MGP for 6 hr. Cytostatic activity was thermolabile (1 hr/56 degrees C). Fractionation of peritoneal cell supernatant by HPLC resulted in the recovery of one peak, eluting at 70 kDa, which was cytostatic for 3LL cells. The cytostatic supernatant was tested for tumor necrosis factor activity (TNF): no correlation between TNF and cytostatic activity was observed. Indeed, even high amounts of mouse rTNF did not affect 3LL cell growth. Moreover, monoclonal antibodies (MAbs) to mouse TNF had no effect on cytostasis, indicating absence of synergistic interactions of the cytostatic factor with low levels of mouse TNF.

Animals↗
PubMed1987

Remote effects of inflammation on non-specific immunity.

Following inflammation induced in mice with non-biodegradable, non-diffusible, and non-antigenic substances, host resistance is increased against bacteria, parasites and malignant cells injected at a distance from the inflammatory focus. This resistance is also increased in germ-free and nude mice. The increased resistance is correlated with (1) an increased leukopoiesis induced, at least in part, by a protein (MW = 40 kDa, pI = 5.2) which, in vitro, is able to induce the differentiation of bone-marrow cells into polymorphs; (2) the occurrence of giant cells in the granuloma which, after incubation in vitro, release an immunostimulating protein able to activate mice macrophages in vivo; (3) activation in vivo of liver and spleen macrophages following the occurrence, both in granuloma and in serum, of a protein (MW = 56 kDa, pI = 5) which, contrary to endotoxin, is heat-labile and can fully protect mice against Listeria monocytogenes. Furthermore, this protein, which is different from TNF and GM CSF, is able to activate macrophages against Lewis tumor cells. The same protein can be isolated from rat and is antigenically related to a human protein having the same biological activity.

Animals↗
PubMed1983

Immunostimulatory mouse granuloma protein.

Earlier studies have shown that from subcutaneous talc-induced granuloma in mice, a fraction could be extracted that fully protected mice against Listeria monocytogenes. Using standard biochemical procedures--i.e., ammonium sulfate fractionation, preparative electrophoresis, gel filtration chromatography, isoelectric focusing, and preparative polyacrylamide gel electrophoresis--we have now purified an active factor to homogeneity. A single band was obtained in NaDodSO4/polyacrylamide gel with an apparent Mr of 55,000. It migrated with alpha 1-globulins and the isoelectric point was 5 +/- 0.1. The biological activity was destroyed with Pronase but not with trypsin and a monospecific polyclonal rabbit antiserum was obtained. The intravenous injection of 5 micrograms of this "mouse granuloma protein" fully protects mice against a lethal inoculum of L. monocytogenes. Moreover, after their incubation with 10 nM mouse granuloma protein, mouse peritoneal cells became cytostatic against Lewis carcinoma cells.

Animals↗
PubMed1978

The threonine-sensitive homoserine dehydrogenase and aspartokinase activities of Escherichia coli K12. Carboxymethylation of the enzyme: threonine binding and inhibition are functionally dissociable.

The inactivation of the aspartokinase I-homoserine dehydrogenase I by iodoacetic acid and the effect on the sensitivity to its inhibitor, L-threonine, were examined. Both aspartokinase and homoserine dehydrogenase inactivation, as well as the dehydrogenase desensitization toward L-threonine occur as a pseudo-first order process. During its inactivation, the aspartokinase remains sensitive to L-threonine. At 50% inactivation, the inhibition curve of the aspartokinase by L-threonine displays homotropic cooperative effects. This alkylated protein retains eight binding sites for L-threonine. During the carboxymethylation, the protein remains in the tetrameric form until half of the kinase activity is lost. At the end of the inactivation aggregate forms and dimers appear.

Alkylation↗
PubMedDate not supplied

[Severe hypofibrinegenemia after rattlesnake envenomation in France].

A 22-year-old man, who maintains illegally numerous exotic snakes at home (suburbs of Paris), was bitten by one of his Bresilian rattlesnakes, the lance-headed viper Bothrops moojeni, with grade III envenomation. The fibrinogen was less than 0,5 g/L, the prothombin time was 22%, the activated partial thromboplastin time was 94 seconds. The authors discuss the biological and clinical management of this defibrination, due to defibrinogenating proteases (thrombin-like enzymes), present in Bothrops moojeni venom. The patient received 7 vials of an antivenom directed to another crotal, Bothrops lanceolatus. Despite the importance of defibrinogenation, there was only a few clinical evidence of bleeding, according to the literature. The normalization of coagulation studies occured only after day 11. This case-report outlines the danger of the increase of exotic snakes maintained as pet in France and the difficulties to obtain specific antivenoms.

Adult↗
PubMedDate not supplied

Increased phagocytic activity in mice treated by a mouse granuloma protein.

Intravenous injection of a protein extracted from a talc-induced granuloma (MGP) enhanced the blood clearance of a highly virulent strain of Salmonella typhimurium. This protein was able to enhance mouse resistance to systemic infection with Listeria monocytogenes when injected one or two days prior to infection. Furthermore, since MGP-treated athymic mice were also protected against Listeria infection, mature T cells were most likely not involved in this enhanced resistance. These findings suggest that this increased resistance to infection correlates with an activation of liver and spleen macrophages. This protective effect of MGP was not due to possible endotoxin contamination of the preparation, as the MGP activity was destroyed by heating.

Adjuvants, Immunologic↗