Dominique Vidal - Academia.edu (original) (raw)
Papers by Dominique Vidal
Toxins necessary for Bacillus anthracis pathogenesis are made of three sub-units : PA (protective... more Toxins necessary for Bacillus anthracis pathogenesis are made of three sub-units : PA (protective antigen), LF (lethal factor) and EF (edema factor). Anti-PA recombinant antibodies have been developed for anthrax treatment, but other sub-units have not been targeted despite anthrax experts recommendations. Here, we describe an anti-LF scFv that was obtained from a macaque (Macaca fascicularis) immune antibody gene library (1.8x10 8 clones) in pHAL14 phagemid vector. One scFv clone (2LF) selected from the library, had a high-affinity (KD = 1.02 nM), was highly neutralizing in the standardized in vitro (IC50 = 1.17 ± 0.06 nM) and in an in vivo assays. The genes encoding 2LF are similar to human immunoglobulin germline genes, and assigned to subgroups of human V, (D) or J genes by IMGT/V-QUEST. 2LF framework regions have a 84% identity with their most similar, germinally encoded human counterparts. This scFv neutralizes the anthrax lethal toxin by inhibiting the formation of the LF-PA complex, as shown in a competition assay. This inhibition suggests that 2LF interacts with domain 1 of LF, which is partially shared with EF and 2LF also reacted with EF, in ELISA and SPR. A 2LF-derived IgG, targeting LF and maybe EF, would be suitable for medical use.
Annales pharmaceutiques françaises, 1990
We have obtained polyclonal anti-T-2 toxin antibodies with high affinity to T-2 toxin (K = 0.34 x... more We have obtained polyclonal anti-T-2 toxin antibodies with high affinity to T-2 toxin (K = 0.34 x 10(9) l/M at 4 degrees C), crossreacting with HT-2 toxin, one of the major metabolites. We have assessed these antibodies in prevention and therapy of the acute intoxication. When given 24 h before 1 or 2 LD50 of T-2 toxin (5 or 10 mg/kg), the antibodies decreased the mortality from 67% to 37%, or from 100% to 83% respectively with an optimal antibody dosage of 100 mg/kg. In contrast when given 30 mn after the toxin, anti-T-2 toxin antibodies increased the mortality; in the same way non specific antibodies increased the mortality of mice intoxicated with T-2 toxin.
Biochimie, 1972
This work describes a preparative procedure to obtain IFs, one of the main translation initiation... more This work describes a preparative procedure to obtain IFs, one of the main translation initiation factors, in a 35S labelled form. 3.~S IF~ thus prepared was 80 p. cent pure. The main features of 35S IF~ binding to E. colt ribosomes have been specified by means of the sucrose density sedimentation technique. At 5.10-3 M Mg ÷*, :~5S IF,~ readily forms a stable complex with 30S subunits-previously 'washed free of their endogeneous factors-but not with 50S subnnits. When the Mg ÷÷ concentration is lowered to 2.10 4 M, appreciable binding to the 50S subunits is observed. After mixing 35S IF~ with 70S ribosomes, one can detect the appearance of 30S-35S IF3 complexes as a result of the dissociating effect of IF~. The staechiometry of this binding corresponds to one molecule of factor per 30S subunit,-~S-IFz is released from 30S subunits after or during formation of an initiation complex. In the presence of streptomycin or neomycin at doses inhibiting spontaneous 70S dissociation, formation of 30S-35S-IFz complex cannot be detected. These antibiotics as well as kasugamycin or colicin F~ do not inhibit 35S-IF:, binding to pre-dissociated 30S at low Mg ÷÷.
Revue Francophone des Laboratoires, 2009
Resume Le reseau national des laboratoires Biotox-Piratox est une des composantes des plans natio... more Resume Le reseau national des laboratoires Biotox-Piratox est une des composantes des plans nationaux de sauvegarde des populations. Il tire profit des lecons de la crise « charbon » de 2001, afin d’assurer l’utilisation optimale des capacites analytiques des laboratoires nationaux. L’organisation generale du reseau est articulee en trois niveaux de competence, les laboratoires sentinelles, les laboratoires de zones de defense et les laboratoires a competence nationale. Il met ainsi a la disposition des autorites locales et nationales une capacite de reponse flexible et adaptee aux actes malveillants ou alertes mettant en cause des agents biologiques ou des toxiques de guerre ou industriels.
Revue Francophone des Laboratoires, 2009
La maladie du charbon est une zoo-anthroponose touchant les troupeaux et parfois l'homme en conta... more La maladie du charbon est une zoo-anthroponose touchant les troupeaux et parfois l'homme en contact avec les produits animaux dans un contexte de maladies professionnelles, industrielles ou de toxi-infections alimentaires. Elle se présente sous formes cutanée, digestive et respiratoire. Bacillus anthracis est l'agent responsable de la maladie du charbon. C'est un bacille à Gram positif, immobile, capsulé, non hémolytique formant des spores. Alors qu'il est facile de traiter le charbon cutané par les antibiotiques, le charbon digestif, le charbon méningé et le charbon pulmonaire (ou d'inhalation) sont redoutables. Le cycle du charbon met en jeu une forme sporulée tellurique et une forme végétative capsulée produisant les toxines charbonneuses chez l'hôte. Toujours présente dans l'environnement hydrotellurique des zones d'enzootie, la maladie réémerge périodiquement en fonction des évolutions climatiques et écologiques ou des activités humaines. La grande résistance des spores dans l'environnement et la virulence du bacille du charbon en font un agent potentiel de guerre bactériologique et de bioterrorisme de premier plan. Il est donc important de savoir faire le diagnostic biologique de cette maladie qui s'appuie sur des techniques de bactériologie classique, de biologie moléculaire et d'immunologie. Bacillus anthracis-maladie du charbon-diagnostic-PCR.
Sociologie du travail
Issu d’une enquete menee en Cote d’Ivoire entre 1999 et 2001, l’ouvrage de Melanie Jacquemin appo... more Issu d’une enquete menee en Cote d’Ivoire entre 1999 et 2001, l’ouvrage de Melanie Jacquemin apporte une contribution originale a trois des difficiles questions devant lesquelles se trouve placee la sociologie de l’emploi domestique, notamment dans les pays du Sud. Sans trahir le propos de l’auteur qui ne les enonce pas telles quelles, on peut les formuler de la maniere suivante : observe-t-on dans le service domestique la persistance de relations de type traditionnel dans une societe gagnee ...
Infection and Immunity
The effects of T-2 toxin on mouse peritoneal macrophages were investigated. Scanning electron mic... more The effects of T-2 toxin on mouse peritoneal macrophages were investigated. Scanning electron microscopy of macrophages treated in vitro with T-2 toxin revealed retraction of pseudopodia. Protein synthesis was inhibited after in vitro contact with T-2 toxin but was not affected 24 h after injection of a sublethal dose of toxin into mice. There was reduction in the phagocytosis of Pseudomonas aeruginosa when macrophages were exposed in vitro to T-2 toxin and when mice were injected with T-2 toxin. Clearance of colloidal carbon was not modified after T-2 toxin injection, whereas spleen weight was decreased 24 h after T-2 injection. T-2 toxin enhanced the mortality of mice infected with Salmonella typhimurium C5S when it was administered 24 h prior to oral challenge with the bacterium.
Applied and Environmental Microbiology
Fusarium sambucinum Fuckel 8099-1 was grown on Czapek-Dox peptone-supplemented medium at 15 degre... more Fusarium sambucinum Fuckel 8099-1 was grown on Czapek-Dox peptone-supplemented medium at 15 degrees C for 14 days, and the cultures were investigated for diacetoxyscirpenol (DAS) production by liquid-liquid extraction and gas chromatography. The addition of 150 mg of sorbic acid, a tricarboxylic acid cycle inhibitor, per liter stimulated both fungal growth and DAS production. Among the beta-hydroxy-beta-methylglutaryl coenzyme A precursors tested, isovaleric acid completely inhibited fungal growth and DAS production, ethyl isovalerate did not support a significant increase in DAS production, and L-leucine partially inhibited DAS production, showing that L-leucine and isovaleric acid catabolisms do not induce trichothecene biosynthesis. Solid particles (cork powder) were necessary for DAS production in stationary cultures but did not influence DAS production in shaken cultures. Shaking strongly stimulated DAS production and fungal growth.
Applied and environmental microbiology
SpringerReference
Anthrax is a zoonotic disease caused by Bacillus anthracis. Skin disease is the most common form ... more Anthrax is a zoonotic disease caused by Bacillus anthracis. Skin disease is the most common form in humans. Pulmonary anthrax related to the inhalation of airborne germs develops after a silent incubation period of several days and followed by acute respiratory distress. Diagnosis is a difficult task and generally based on demonstration of Bacillus anthracis on direct examination. Despite the sensitivity of B. anthracis to penicillin, treatment is rarely successful.
Annales Pharmaceutiques Françaises
Working with pathogens or genetically engineered micro-organisms is a potential hazard for scient... more Working with pathogens or genetically engineered micro-organisms is a potential hazard for scientists, health care workers, employees of pharmaceutical industry, and also for the environment. Carelessness, poor technique in the handling of infectious materials, needle sting or infectious aerosol exposure are the cause of laboratory acquired infection. Biosafety, corollary of biocontamination, is based on the combination of good microbiological techniques, facility design of the laboratory and safety equipment. So, four biosafety levels are appropriate for the operations performed and the hazard posed by the infectious agents.
Biotechnology therapeutics
The immunomodulating properties of arglabin, a sesquiterpene lactone isolated from Artemisia myri... more The immunomodulating properties of arglabin, a sesquiterpene lactone isolated from Artemisia myriantha Wall. (Asteraceae) were investigated using the murine macrophage tumor line J774.1. Arglabin-stimulated macrophages displayed a strong cytotoxic activity and the lowest doses (1.25 micrograms/mL and 0.125 micrograms/mL) induced a significant stimulation of cell mitochondrial metabolism, which correlated with [3H]TdR uptake by J774.1 cells under the same experimental conditions. In addition, the secretion of cytokines involved in host defence mechanisms--IL-1, TNF-alpha, and IL-2--was investigated upon incubation of J774-1 cells with arglabin. Arglabin triggered the production of the three cytokines from J774-1 cells. However, the pattern of cytokine secretion differed to some extent, according to the methodology used for cytokine measurement: either traditional bioassay or specific immunoassay (ELISA). Our data emphasize a possible proliferative effect of arglabin in the traditional bioassays, at least for the highest concentrations used. The results were verified with specific ELISA immunoassays. Using either method, lower concentrations of arglabin (ranging from 12.5 micrograms/mL to 0.125 micrograms/mL) were the most effective in inducing IL-1, TNF-alpha, or IL-2 secretion. In addition, preliminary data on phagocytosis showed that arglabin enhanced the uptake of fluorescent latex beads by J774.1 cells.
Acta microbiologica Hungarica
The effects of patulin and T-2 toxin were investigated on immunological responses of Balb/c mice.... more The effects of patulin and T-2 toxin were investigated on immunological responses of Balb/c mice. In vitro patulin had a stimulatory effect on splenocytes at lower concentration (1 nM to 10 nM) and strongly inhibited lymphocyte proliferation at higher concentrations (ID50 from 0.02 to 0.24 microM depending on mitogens). In the same experiments T-2 toxin was 100-fold more potent (ID50 from 0.7 to 2 nM). In vivo studies on immunity were performed in mice receiving Bordetella pertussis antigens and keyhole limpet haemocyanin. Patulin significantly reduced delayed type hypersensitivity to B. pertussis antigen and did not reduce anti-KLH antibody production. T-2 toxin had no effect on delayed type hypersensitivity and reduced anti-KLH antibody production. Splenocytes were harvested in mice with or without antigen stimulation to assess mitogenic responses. Patulin generally increased splenocyte proliferation, therefore T-2 toxin effect depended on the immunological status of mice and on the dose injected. At the lower doses (0.8 mg/kg), T-2 toxin enhanced responses to mitogen, but at the greater dose (1.6 mg/kg) T-2 toxin enhanced responses to mitogen of antigen stimulated mice and decreased responses of unstimulated mice.
Annales Pharmaceutiques Françaises
When bacteria grow in close association with solid surface, they constitute a microbial community... more When bacteria grow in close association with solid surface, they constitute a microbial community tight included in the exopolymer glycocalyx. Many laboratory studies have shown that these bacteria are 10 to 100 folds more resistant to disinfectants than the bacteria of the same strain in suspension. Several factors are responsible for this resistance: the glycocalyx which limits the diffusion and reacts with the disinfectant, the more or less dense repartition of the bacteria inside the biofilm, their physiologic state with reduced metabolism, and the surface on which is the biofilm. The activity assessment of disinfectant agents is achieved with standardized methods. They must take into account not only the conditions in which the disinfectants are employed, but also the micro-organism state. Experimental results showing the resistance of biofilm bacteria must lead to elaborate methods allowing the assessment of bactericide activity of disinfectants against biofilm bacteria.
Revue Francophone des Laboratoires, 2009
Burkholderia pseudomallei est l'agent de la mélioïdose. Il s'agit d'une bactérie de l'environneme... more Burkholderia pseudomallei est l'agent de la mélioïdose. Il s'agit d'une bactérie de l'environnement hydrotellurique, hautement pathogène pour l'homme. En France et en Europe, les cas de mélioïdose sont des cas d'importation, alors qu'en Asie du Sud-est et en Australie, cette maladie sévit sous forme d'endémie. La répartition géographique de cette maladie s'étend et touche maintenant le Brésil, Madagascar et l'Ile de la Réunion. Le diagnostic phénotypique de cette bactérie est aisé, mais il faut savoir penser à ce micro-organisme, qui n'est pas fréquent sous nos contrées. Son antibiogramme spécifique constitue une aide précieuse au diagnostic. Cette maladie est d'autant plus grave que les possibilités de traitement sont très restreintes et reposent sur une lourde antibiothérapie. Burkholderia pseudomallei-mélioïdose-diagnostic-thailandensis.
Plasmid, 2009
Francisella tularensis is the causative agent of tularemia, a zoonotic disease often transmitted ... more Francisella tularensis is the causative agent of tularemia, a zoonotic disease often transmitted to humans by infected animals. The lack of useful specific genetic tools has long hampered the study of F. tularensis subspecies. We identified and characterized two new plasmids, pF242 and pF243, isolated from Francisella philomiragia strains ATCC 25016 and ATCC 25017, respectively. Sequence analysis revealed that pF242 and pF243 are closely related to pC194 and pFNL10 plasmids, respectively. Two generations of pF242- and pF243-based shuttle vectors, harboring several antibiotic resistance markers, were developed. We used the first generation to compare transformation efficiencies in two virulent F. tularensis subspecies. We found that electroporation was more efficient than cryotransformation: almost all vectors tested were successfully introduced by electroporation into Francisella strains with a high level of efficiency. The second generation of shuttle vectors, containing a multiple...
Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie, 1985
Sodium hypochlorite was used to suppress diacetoxyscirpenol cutaneous toxicity; mice skin can be ... more Sodium hypochlorite was used to suppress diacetoxyscirpenol cutaneous toxicity; mice skin can be decontaminated with "Eau de Javel" (1 p. 100 free chlorine) if application is performed less than 15 min. after contact with toxin.
Toxins necessary for Bacillus anthracis pathogenesis are made of three sub-units : PA (protective... more Toxins necessary for Bacillus anthracis pathogenesis are made of three sub-units : PA (protective antigen), LF (lethal factor) and EF (edema factor). Anti-PA recombinant antibodies have been developed for anthrax treatment, but other sub-units have not been targeted despite anthrax experts recommendations. Here, we describe an anti-LF scFv that was obtained from a macaque (Macaca fascicularis) immune antibody gene library (1.8x10 8 clones) in pHAL14 phagemid vector. One scFv clone (2LF) selected from the library, had a high-affinity (KD = 1.02 nM), was highly neutralizing in the standardized in vitro (IC50 = 1.17 ± 0.06 nM) and in an in vivo assays. The genes encoding 2LF are similar to human immunoglobulin germline genes, and assigned to subgroups of human V, (D) or J genes by IMGT/V-QUEST. 2LF framework regions have a 84% identity with their most similar, germinally encoded human counterparts. This scFv neutralizes the anthrax lethal toxin by inhibiting the formation of the LF-PA complex, as shown in a competition assay. This inhibition suggests that 2LF interacts with domain 1 of LF, which is partially shared with EF and 2LF also reacted with EF, in ELISA and SPR. A 2LF-derived IgG, targeting LF and maybe EF, would be suitable for medical use.
Annales pharmaceutiques françaises, 1990
We have obtained polyclonal anti-T-2 toxin antibodies with high affinity to T-2 toxin (K = 0.34 x... more We have obtained polyclonal anti-T-2 toxin antibodies with high affinity to T-2 toxin (K = 0.34 x 10(9) l/M at 4 degrees C), crossreacting with HT-2 toxin, one of the major metabolites. We have assessed these antibodies in prevention and therapy of the acute intoxication. When given 24 h before 1 or 2 LD50 of T-2 toxin (5 or 10 mg/kg), the antibodies decreased the mortality from 67% to 37%, or from 100% to 83% respectively with an optimal antibody dosage of 100 mg/kg. In contrast when given 30 mn after the toxin, anti-T-2 toxin antibodies increased the mortality; in the same way non specific antibodies increased the mortality of mice intoxicated with T-2 toxin.
Biochimie, 1972
This work describes a preparative procedure to obtain IFs, one of the main translation initiation... more This work describes a preparative procedure to obtain IFs, one of the main translation initiation factors, in a 35S labelled form. 3.~S IF~ thus prepared was 80 p. cent pure. The main features of 35S IF~ binding to E. colt ribosomes have been specified by means of the sucrose density sedimentation technique. At 5.10-3 M Mg ÷*, :~5S IF,~ readily forms a stable complex with 30S subunits-previously 'washed free of their endogeneous factors-but not with 50S subnnits. When the Mg ÷÷ concentration is lowered to 2.10 4 M, appreciable binding to the 50S subunits is observed. After mixing 35S IF~ with 70S ribosomes, one can detect the appearance of 30S-35S IF3 complexes as a result of the dissociating effect of IF~. The staechiometry of this binding corresponds to one molecule of factor per 30S subunit,-~S-IFz is released from 30S subunits after or during formation of an initiation complex. In the presence of streptomycin or neomycin at doses inhibiting spontaneous 70S dissociation, formation of 30S-35S-IFz complex cannot be detected. These antibiotics as well as kasugamycin or colicin F~ do not inhibit 35S-IF:, binding to pre-dissociated 30S at low Mg ÷÷.
Revue Francophone des Laboratoires, 2009
Resume Le reseau national des laboratoires Biotox-Piratox est une des composantes des plans natio... more Resume Le reseau national des laboratoires Biotox-Piratox est une des composantes des plans nationaux de sauvegarde des populations. Il tire profit des lecons de la crise « charbon » de 2001, afin d’assurer l’utilisation optimale des capacites analytiques des laboratoires nationaux. L’organisation generale du reseau est articulee en trois niveaux de competence, les laboratoires sentinelles, les laboratoires de zones de defense et les laboratoires a competence nationale. Il met ainsi a la disposition des autorites locales et nationales une capacite de reponse flexible et adaptee aux actes malveillants ou alertes mettant en cause des agents biologiques ou des toxiques de guerre ou industriels.
Revue Francophone des Laboratoires, 2009
La maladie du charbon est une zoo-anthroponose touchant les troupeaux et parfois l'homme en conta... more La maladie du charbon est une zoo-anthroponose touchant les troupeaux et parfois l'homme en contact avec les produits animaux dans un contexte de maladies professionnelles, industrielles ou de toxi-infections alimentaires. Elle se présente sous formes cutanée, digestive et respiratoire. Bacillus anthracis est l'agent responsable de la maladie du charbon. C'est un bacille à Gram positif, immobile, capsulé, non hémolytique formant des spores. Alors qu'il est facile de traiter le charbon cutané par les antibiotiques, le charbon digestif, le charbon méningé et le charbon pulmonaire (ou d'inhalation) sont redoutables. Le cycle du charbon met en jeu une forme sporulée tellurique et une forme végétative capsulée produisant les toxines charbonneuses chez l'hôte. Toujours présente dans l'environnement hydrotellurique des zones d'enzootie, la maladie réémerge périodiquement en fonction des évolutions climatiques et écologiques ou des activités humaines. La grande résistance des spores dans l'environnement et la virulence du bacille du charbon en font un agent potentiel de guerre bactériologique et de bioterrorisme de premier plan. Il est donc important de savoir faire le diagnostic biologique de cette maladie qui s'appuie sur des techniques de bactériologie classique, de biologie moléculaire et d'immunologie. Bacillus anthracis-maladie du charbon-diagnostic-PCR.
Sociologie du travail
Issu d’une enquete menee en Cote d’Ivoire entre 1999 et 2001, l’ouvrage de Melanie Jacquemin appo... more Issu d’une enquete menee en Cote d’Ivoire entre 1999 et 2001, l’ouvrage de Melanie Jacquemin apporte une contribution originale a trois des difficiles questions devant lesquelles se trouve placee la sociologie de l’emploi domestique, notamment dans les pays du Sud. Sans trahir le propos de l’auteur qui ne les enonce pas telles quelles, on peut les formuler de la maniere suivante : observe-t-on dans le service domestique la persistance de relations de type traditionnel dans une societe gagnee ...
Infection and Immunity
The effects of T-2 toxin on mouse peritoneal macrophages were investigated. Scanning electron mic... more The effects of T-2 toxin on mouse peritoneal macrophages were investigated. Scanning electron microscopy of macrophages treated in vitro with T-2 toxin revealed retraction of pseudopodia. Protein synthesis was inhibited after in vitro contact with T-2 toxin but was not affected 24 h after injection of a sublethal dose of toxin into mice. There was reduction in the phagocytosis of Pseudomonas aeruginosa when macrophages were exposed in vitro to T-2 toxin and when mice were injected with T-2 toxin. Clearance of colloidal carbon was not modified after T-2 toxin injection, whereas spleen weight was decreased 24 h after T-2 injection. T-2 toxin enhanced the mortality of mice infected with Salmonella typhimurium C5S when it was administered 24 h prior to oral challenge with the bacterium.
Applied and Environmental Microbiology
Fusarium sambucinum Fuckel 8099-1 was grown on Czapek-Dox peptone-supplemented medium at 15 degre... more Fusarium sambucinum Fuckel 8099-1 was grown on Czapek-Dox peptone-supplemented medium at 15 degrees C for 14 days, and the cultures were investigated for diacetoxyscirpenol (DAS) production by liquid-liquid extraction and gas chromatography. The addition of 150 mg of sorbic acid, a tricarboxylic acid cycle inhibitor, per liter stimulated both fungal growth and DAS production. Among the beta-hydroxy-beta-methylglutaryl coenzyme A precursors tested, isovaleric acid completely inhibited fungal growth and DAS production, ethyl isovalerate did not support a significant increase in DAS production, and L-leucine partially inhibited DAS production, showing that L-leucine and isovaleric acid catabolisms do not induce trichothecene biosynthesis. Solid particles (cork powder) were necessary for DAS production in stationary cultures but did not influence DAS production in shaken cultures. Shaking strongly stimulated DAS production and fungal growth.
Applied and environmental microbiology
SpringerReference
Anthrax is a zoonotic disease caused by Bacillus anthracis. Skin disease is the most common form ... more Anthrax is a zoonotic disease caused by Bacillus anthracis. Skin disease is the most common form in humans. Pulmonary anthrax related to the inhalation of airborne germs develops after a silent incubation period of several days and followed by acute respiratory distress. Diagnosis is a difficult task and generally based on demonstration of Bacillus anthracis on direct examination. Despite the sensitivity of B. anthracis to penicillin, treatment is rarely successful.
Annales Pharmaceutiques Françaises
Working with pathogens or genetically engineered micro-organisms is a potential hazard for scient... more Working with pathogens or genetically engineered micro-organisms is a potential hazard for scientists, health care workers, employees of pharmaceutical industry, and also for the environment. Carelessness, poor technique in the handling of infectious materials, needle sting or infectious aerosol exposure are the cause of laboratory acquired infection. Biosafety, corollary of biocontamination, is based on the combination of good microbiological techniques, facility design of the laboratory and safety equipment. So, four biosafety levels are appropriate for the operations performed and the hazard posed by the infectious agents.
Biotechnology therapeutics
The immunomodulating properties of arglabin, a sesquiterpene lactone isolated from Artemisia myri... more The immunomodulating properties of arglabin, a sesquiterpene lactone isolated from Artemisia myriantha Wall. (Asteraceae) were investigated using the murine macrophage tumor line J774.1. Arglabin-stimulated macrophages displayed a strong cytotoxic activity and the lowest doses (1.25 micrograms/mL and 0.125 micrograms/mL) induced a significant stimulation of cell mitochondrial metabolism, which correlated with [3H]TdR uptake by J774.1 cells under the same experimental conditions. In addition, the secretion of cytokines involved in host defence mechanisms--IL-1, TNF-alpha, and IL-2--was investigated upon incubation of J774-1 cells with arglabin. Arglabin triggered the production of the three cytokines from J774-1 cells. However, the pattern of cytokine secretion differed to some extent, according to the methodology used for cytokine measurement: either traditional bioassay or specific immunoassay (ELISA). Our data emphasize a possible proliferative effect of arglabin in the traditional bioassays, at least for the highest concentrations used. The results were verified with specific ELISA immunoassays. Using either method, lower concentrations of arglabin (ranging from 12.5 micrograms/mL to 0.125 micrograms/mL) were the most effective in inducing IL-1, TNF-alpha, or IL-2 secretion. In addition, preliminary data on phagocytosis showed that arglabin enhanced the uptake of fluorescent latex beads by J774.1 cells.
Acta microbiologica Hungarica
The effects of patulin and T-2 toxin were investigated on immunological responses of Balb/c mice.... more The effects of patulin and T-2 toxin were investigated on immunological responses of Balb/c mice. In vitro patulin had a stimulatory effect on splenocytes at lower concentration (1 nM to 10 nM) and strongly inhibited lymphocyte proliferation at higher concentrations (ID50 from 0.02 to 0.24 microM depending on mitogens). In the same experiments T-2 toxin was 100-fold more potent (ID50 from 0.7 to 2 nM). In vivo studies on immunity were performed in mice receiving Bordetella pertussis antigens and keyhole limpet haemocyanin. Patulin significantly reduced delayed type hypersensitivity to B. pertussis antigen and did not reduce anti-KLH antibody production. T-2 toxin had no effect on delayed type hypersensitivity and reduced anti-KLH antibody production. Splenocytes were harvested in mice with or without antigen stimulation to assess mitogenic responses. Patulin generally increased splenocyte proliferation, therefore T-2 toxin effect depended on the immunological status of mice and on the dose injected. At the lower doses (0.8 mg/kg), T-2 toxin enhanced responses to mitogen, but at the greater dose (1.6 mg/kg) T-2 toxin enhanced responses to mitogen of antigen stimulated mice and decreased responses of unstimulated mice.
Annales Pharmaceutiques Françaises
When bacteria grow in close association with solid surface, they constitute a microbial community... more When bacteria grow in close association with solid surface, they constitute a microbial community tight included in the exopolymer glycocalyx. Many laboratory studies have shown that these bacteria are 10 to 100 folds more resistant to disinfectants than the bacteria of the same strain in suspension. Several factors are responsible for this resistance: the glycocalyx which limits the diffusion and reacts with the disinfectant, the more or less dense repartition of the bacteria inside the biofilm, their physiologic state with reduced metabolism, and the surface on which is the biofilm. The activity assessment of disinfectant agents is achieved with standardized methods. They must take into account not only the conditions in which the disinfectants are employed, but also the micro-organism state. Experimental results showing the resistance of biofilm bacteria must lead to elaborate methods allowing the assessment of bactericide activity of disinfectants against biofilm bacteria.
Revue Francophone des Laboratoires, 2009
Burkholderia pseudomallei est l'agent de la mélioïdose. Il s'agit d'une bactérie de l'environneme... more Burkholderia pseudomallei est l'agent de la mélioïdose. Il s'agit d'une bactérie de l'environnement hydrotellurique, hautement pathogène pour l'homme. En France et en Europe, les cas de mélioïdose sont des cas d'importation, alors qu'en Asie du Sud-est et en Australie, cette maladie sévit sous forme d'endémie. La répartition géographique de cette maladie s'étend et touche maintenant le Brésil, Madagascar et l'Ile de la Réunion. Le diagnostic phénotypique de cette bactérie est aisé, mais il faut savoir penser à ce micro-organisme, qui n'est pas fréquent sous nos contrées. Son antibiogramme spécifique constitue une aide précieuse au diagnostic. Cette maladie est d'autant plus grave que les possibilités de traitement sont très restreintes et reposent sur une lourde antibiothérapie. Burkholderia pseudomallei-mélioïdose-diagnostic-thailandensis.
Plasmid, 2009
Francisella tularensis is the causative agent of tularemia, a zoonotic disease often transmitted ... more Francisella tularensis is the causative agent of tularemia, a zoonotic disease often transmitted to humans by infected animals. The lack of useful specific genetic tools has long hampered the study of F. tularensis subspecies. We identified and characterized two new plasmids, pF242 and pF243, isolated from Francisella philomiragia strains ATCC 25016 and ATCC 25017, respectively. Sequence analysis revealed that pF242 and pF243 are closely related to pC194 and pFNL10 plasmids, respectively. Two generations of pF242- and pF243-based shuttle vectors, harboring several antibiotic resistance markers, were developed. We used the first generation to compare transformation efficiencies in two virulent F. tularensis subspecies. We found that electroporation was more efficient than cryotransformation: almost all vectors tested were successfully introduced by electroporation into Francisella strains with a high level of efficiency. The second generation of shuttle vectors, containing a multiple...
Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie, 1985
Sodium hypochlorite was used to suppress diacetoxyscirpenol cutaneous toxicity; mice skin can be ... more Sodium hypochlorite was used to suppress diacetoxyscirpenol cutaneous toxicity; mice skin can be decontaminated with "Eau de Javel" (1 p. 100 free chlorine) if application is performed less than 15 min. after contact with toxin.