Search results for "Muri"
showing 10 items of 289 documents
A microplate version of the SOS/umu-test for rapid detection of genotoxins and genotoxic potentials of environmental samples
1991
Abstract The umu-microtest is a miniaturized automated short-term test version proposed for screening of umuC-dependent mutagenic potentials of chemicals relevant to environmental pollution, river water and industrial waste water. The test is based on the SOS/umu-test and has been modified in order to allow extensive testing of environmental samples. Genetically engineered Salmonella typhimurium (TA1535/pSK1002) are incubated on a microplate rotor in a sloping position for 2 h with the test samples, followed by addition of fresh culture medium to reach a 10-fold dilution of the incubation medium. 2 h later, the activity of the β-galactosidase, which reflects umuC induction, is determined co…
Recovery Estimation of Dried Foodborne Pathogens Is Directly Related to Rehydration Kinetics.
2016
International audience; Drying is a common process which is used to preserve food products and technological microorganisms, but which is deleterious for the cells. The aim of this study is to differentiate the effects of drying alone from the effects of the successive and necessary rehydration. Rehydration of dried bacteria is a critical step already studied in starter culture but not for different kinetics and not for pathogens. In the present study, the influence of rehydration kinetics was investigated for three foodborne pathogens involved in neonatal diseases caused by the consumption of rehydrated milk powder: Salmonella enterica subsp. enterica serovar Typhimurium, Salmonella enteri…
Salmonella enterica serotype Typhimurium DT 104 antibiotic resistance genomic island I in serotype paratyphi B
2002
We have identified Salmonella genomic island I (SGI1) in an isolate of Salmonella enterica serotype Paratyphi B. This antibiotic-resistance gene cluster, which confers multidrug resistance, has been previously identified in S. enterica serotype Typhimurium phage types DT 104 and DT 120 and in S. enterica serotype Agona.
Epoxides metabolically produced from some known carcinogens and from some clinically used drugs. I. Differences in mutagenicity.
1975
The epoxide metabolites of two clinically used drugs and an experimental psychotropic agent, carbamazepine 10,11-oxide, cyproheptadine 10,11-oxide and cyclobenzaprine 10,11-oxide, were fully devoid of any mutagenic activity under conditions where K-region-epoxide metabolites of some known carcinogens, such as benzo (a)pyrene, proved to be potent frameshift mutational agents for Salmonella typhimurium TA 1537 and TA 1538. All epoxides tested were non-mutagenic for TA 1535, designed to detect substitution mutations. The 10,11-epoxides of the three drugs, carbamazepine, cyproheptadine and cyclobenzaprine, were not cytotoxic to any of the bacterial tester strains used, precluding that mutagenic…
Prevention of benzo(a)pyrene-induced mutagenicity by homogeneous epoxide hydratase
1976
Benzo(a)pyrene and benz(a)anthrancene which, in contrast to the K-region epoxides benzo(a)pyrene 4,5-oxide and benz(a)anthracene 5,6-oxide, are not mutagenic to Salmonella typhimurium TA 1537 in the absence of mammalian enzyme preparations, were activated by liver microsomes from C3H mice, which had not received any pretreatment, to mutagens reverting this tester strain to histidine prototrophy. Addition of epoxide hydratase inhibitors greatly increased this mutagenicity and addition of pure epoxide hydratase reduced it by more than 95% down to the range of spontaneous mutations as observed in absence of any added mutagen. This demonstrates that the metabolic pathway responsible for the mut…
Novel Penicillin-Type Analogues Bearing a Variable Substituted 2-Azetidinone Ring at Position 6: Synthesis and Biological Evaluation
2015
The synthesis and the biological activity of novel semi-synthetic β-lactam compounds containing an azetidinone moiety joined to the amino-nitrogen of the (+)-6-aminopenicillanic acid (6-APA) as new antibacterial agents is reported. The synthesized compounds were screened for their in vitro antimicrobial activity against a panel of Gram positive and Gram negative pathogens and environmental bacteria. Tested compounds displayed good antimicrobial activity against all tested Gram positive bacteria and for Staphylococcus aureus and Staphylococcus epidermidis antimicrobial activity resulted higher than that of the reference antibiotic. Additionally, in vitro cytotoxic screening was also carried …
Lack of mutagenic and co-mutagenic effects of magnetic fields during magnetic resonance imaging
2001
Mutagenic and co-mutagenic effects of static, pulsed bipolar gradient, and high-frequency magnetic fields, as well as combinations of them, were examined using the Ames test. The Ames test using Salmonella typhimurium bacteria, wild-type strain RTA, preincubation assay, without metabolic activation, was performed. All combinations of magnetic fields were tested with and without co-exposure to N-methyl-N′-nitro-N-nitrosoguanidine and benzo[a]pyrene-4,5-oxide, ethylene oxide, carboplatin, or cisplatin. As expected, chemical mutagens caused a clear-cut increase of the revertants in the Ames test. However, neither the static fields nor a combination of a static magnetic field with the time-vary…
DNA Oxidation Photoinduced by Norharmane Rhenium(I) Polypyridyl Complexes: Effect of the Bidentate N,N′-Ligands on the Damage Profile
2018
Re(I)--polypyridyl complexes have interesting and distinctive photochemical and photosensitizing properties. This work describes the capability to induce (or photoinduce) DNA damage of three Re(I)-complexes with a naturally occurring alkaloid called norharmane (nHo) as ligand: [Re(CO)₃ (nHo)(L)]CF₃ SO₃ where L=2,2'-bipyridine (ReBpy), phenanthroline (RePhen) or dipyrido[3,2-a:2',3'-c]phenazine (ReDppz). The interaction of the complexes with DNA was investigated by steady-state and time-resolved spectroscopy. Data show that the mode and strength of interaction depend on the chemical structure of the bidentate ligand. The complexes show a major static contribution to the overall interaction, …
Safety Evaluation of Food contact paper and board using Chemical Tests and in vitro Bioassays-The role of known and unknown substances
2010
International audience; In vitro toxicological tests has have been proposed as an approach to complement the chemical safety assessment of food contact materials, particularly those with a complex or unknown chemical composition such as paper and board. An EU 5th framework program project “BIOSAFEPAPER – Application of bioassays for safety assessment of paper and board for food contact” specially focused on the application of biotests to paper and board. The project included both chemical characterization and toxicological testing of a representative number of paper and board extracts prepared according to the proposed end use (wet, fatty and dry food contact). Among the concerns addressed …
Free radical scavenging abilities of flavonoids as mechanism of protection against mutagenicity induced by tert-butyl hydroperoxide or cumene hydrope…
2003
Mutagenicity induced by tert-butyl hydroperoxide (BHP) or cumene hydroperoxide (CHP) in Salmonella typhimurium TA102 was effectively reduced by flavonols with 3',4'-hydroxyl groups such as fisetin, quercetin, rutin, isoquercitrin, hyperoxide, myricetin, myricitrin, robinetin, and to a lesser extent also by morin and kaempferol (ID50=0.25-1.05 micromol per plate). With the exception of isorhamnetin, rhamnetin, morin, and kaempferol, closely similar results were obtained with both peroxides. Hydrogenation of the double bond between carbons 2 and 3 (dihydroquercetin, dihydrorobinetin) as well as the additional elimination of the carbonyl function at carbon 4 (catechins) resulted in a loss of a…