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P Lafont

Publications and source records attributed to P Lafont.

At least 37 records · Page 2Linked to original sources
PubMed1979

Determination of mycophenolic acid, penicillic acid, patulin, sterigmatocystin, and aflatoxins in cheese.

A method has been developed for detection of aflatoxins, mycophenolic acid, patulin, penicillic acid, and sterigmatocystin in cheese. It is based on selective extraction with a mixture of equal volumes of 5% sodium chloride, methanol, and aceton, precipitation of caseins at -25 C, defatting with hexane, and removal of extraneous matter by transfer of mycotoxins to chloroform and ethyl acetate. The extract is purified further by column chromatography. Mycotoxins are quantitated on thin layer chromatograms by fluorescence comparisons. Mycophenolic acid, patulin, and penicillic acid are visualized with diethylamine. The limits of detection in cheese are about 20 micrograms/kg for mycophenolic acid, patulin, and sterigmatocystin, 30 microgram/kg for pencillic acid, and 1 microgram/kg for aflatoxins B1 and M1.

Aflatoxins↗
PubMed1979

Immunosuppressive activity of Fusarium toxins. Effects on antibody synthesis and skin grafts of crude extracts, T2-toxin and diacetoxyscirpenol.

The inhibitory effect of crude Fusarium poae extracts, T2-toxin and diacetoxyscirpenol on synthesis of antibody to sheep red blood cells was investigated, as well as the effect of T2-toxin on skin graft rejection. Fusarium crude extracts, T2-toxin and diacetoxyscirpenol cause a significant reduction in thymus weight and inhibit responsiveness to sheep red blood cells. The effect on antibody synthesis was critically dependent on the drug doses used. The effect of an immunosuppressive dose of T2-toxin disappeared within 6 days after the end of the treatment. The administration of T2-toxin subsequent to immunization stops antibody synthesis. T2-toxin significantly prolongs the period required for skin graft rejection.

Animals↗
PubMed1978

[In vitro toxigenesis of Aspergillus fumigatus strain. Production of fumitoxins].

A new class of mycotoxins has been characterized from a strain of Aspergillus fumigatus: the fumitoxins A, B, C and D. The in vitro production of these metabolites is studied. Fumitoxins are common in cultures extracts of most strains of A. fumigatus. They are not detected from A. fischeri. Variations of the levels of these products during the incubation of cultures, and also by using different media, are noted. At all events, the toxicity of crude extracts of the mould, for the chick embryo, is equal to the one of the fumitoxins.

Animals↗
PubMed1978

[New toxins from Aspergillus fumigatus Fresenius].

A strain of Aspergillus fumigatus Fres., isolated from sugar-beet draffs, synthesizes in vitro four toxic metabolites which have not yet been described in these fungal species. Toxic effects of the most abundant of these metabolites "fumitoxin A" have been studed on chick embryo. Artemia salina larvae, cell cultures, and on mice.

Animals↗
PubMed1978

Fumitoxins, new mycotoxins from Aspergillus fumigatus Fres.

Extracts of cultures of Aspergillus fumigatus isolated from silage were lethal to chicken embryos. Using this test and thin-layer chromatography, four UV-absorbing toxins, designated as fumitoxins A, B, C and D, were isolated. Analysis and mass spectrometry of crystallized fumitoxin A, the most abundant in the extract, established its molecular formula to be C31H42O8. Infrared, UV spectroscopy, and chemical reactions suggested that fumitoxin A is a steroid. Fumitoxins appear to be clearly different from the previously described toxins recognized in A. fumigatus.

Animals↗
PubMed1978

[Effect of surface-active agents on Mycobacterium tuberculosis and Mycobacterium bovis. Obtaining chromogenic mycobacteria].

In 18 strains of M. tuberculosis and M. bovis it has been possible to demonstrate the existence, in pure cultures, of elements able to grow in vitro in scotochromogenic mycobacteria. The experimental method used includes a dispersion, under shaking, of organisms in different surface-active agents. The chromogenic strains isolated during the experimentation are eugonic, and PAS- and INH-resistant. Their experimental virulence is different from that of tubercle bacillus. We discuss the signification of this dissociation phenomenon inductible by surface-active agents.

Animals↗
PubMed1978

[Influence of microorganisms on the formation of nitrosamines].

The N-nitroso compounds synthesis from amine and nitrite contained in food is influenced by many factors: -the pH; -the temperature; -the amine basicity; -the presence of organic groups which catalyse or inhibit the reaction. The chemical nitrosation of the amino group takes place at pH between 2 and 4,5. At the near neutrality pH of most of food, this synthetis, cannot be realised. Under these conditions the nitrosamine occurence can be explained by the effect of microorganisms. We have studied the influence of moulds used in cheese making on the nitrosation reaction in a middle where nitrate and amino groups are found together. The middles are realised on caseine or curdled milk, and contained 150 mg/l of nitrate and 100 mg/l of piperidine. The nitrosopiperidine has been identified in all the middles studied. The results are discussed concerning the risk of nitrosamine formation of this type of food during the technological process.

Amines↗
PubMed1975

[The "in vitro" effect of aflatoxin B1 on the development and toxinogenesis of "Aspergillus" gr. "glavus" (author's transl)].

After culture of Aspergillus flavus in synthetic medium supplemented with aflatoxin B1, the level of mycotoxin decreases rapidly during the course of two or three days. Later, in the case of highly toxinogenic strains, a reduction in the production of aflatoxins is observed; whereas, conversely, in the case of low toxinogenesis are obtained in the presence of high levels of the mycotoxin. With all strains of A. flavus, the presence of aflatoxin B1 in the medium at the time of inoculation, moderately limits the growth of mycelium but it has a little effect on the conidial sporulation.

Aflatoxins↗