Comparative Biology of the Resistance to Vitamin K Antagonists: An Overview of the Resistance Mechanisms

Vitamin K antagonists (VKA) are used in human medicine as well as for the management of rodent populations. In both cases, we have to deal with inter-individual resistances. Many mechanisms of resistances are common in humans and rodents. Moreover, with the large use of vitamin K antagonist rodenticides, the resistant phenotype is overrepresented in some rodent populations. Consequently, some resistance mechanisms with a low prevalence in the human population have a higher prevalence in rodent population; thus, they can be more studied in rodents. The aim of this chapter is to cross knowledge coming from human medicine and rodent research in order to better understand each resistance mechanism. After an overview of the essential knowledge for the understanding of the VKA action, this chapter presents the different methods of VKA resistance studying and then it assesses the current knowledge on VKA resistance in humans and rodents

Overview of laboratory methods to diagnose Leptospirosis and to identify and to type leptospires

Leptospirosis is a virulent zoonosis with a global distribution. Pathogenic spirochetes of the genus Leptospira are responsible for this disease, and the primary animal reservoirs are rodentvvvs. Direct and indirect contact with infected urine constitutes the main route of transmission. Renal failure and advanced abortions are frequently observed in animals affected by leptospirosis, causing serious problems for farms. In humans, there is a high rate of mortality (10 percent), and farmers and persons in contact with water are frequently exposed. However, vaccines and strict prevention measures confer protection against leptospirosis. Serological tests facilitate the detection and identification of leptospire strains. Such tests are based on specific surface antigen recognition and are used for clinical analyses. To determine which serovars circulate in the environment, leptospires must be typed. Molecular methods, such as restriction enzyme-based techniques and the sequencing of specific regions, permit serovar identification. Unfortunately, although there are numerous techniques, they are not very efficient, and thus, new methods must be developed. With the advent of genomic sequencing, a substantial amount of information regarding leptospire genomes is now available, facilitating the selection of regions to discriminate between strains. Typing is important for both epidemiologic purposes and clinical analyses.Keywords: Leptospirosis · zoonosis · methods · diagnosi

House Mice as a Real Sanitary Threat of Human and Animal Leptospirosis: Proposal for Integrated Management

International audienceLeptospirosis is a reemerging zoonosis and ranges in severity from benign to sometimes fatal. In cattle, infection may be responsible for abortion and infertility cases causing economic losses. Humans may be contaminated through direct contact with urine of infected animals or indirectly though interaction with urine-contaminated environment. Many wildlife species living close to cattle, especially commensal rodents may play a role in the transmission of leptospires. Because little is known on the epidemiology of nonmaintenance Leptospira serovars, appropriate management is still limited. On a French farm where human and cattle leptospirosis were detected, the transmission cycle was explored to propose appropriate mitigation measures. For that, commensal rodents present on the farm were trapped and their leptospires carriage was studied by molecular methods. Trapped mice were shown to carry two pathogenic Leptospira species (L. interrogans and L. kirschneri). Since these 2 serogroups were simultaneously detected in the trapped mice and in the cows of this farm, we suspected an initial Leptospira transmission from mice to cows requiring an effective management of mice on this farm. Because resistance to anticoagulant rodenticides due to Vkorc1 mutations has been largely described in rodents and first-generation anticoagulant rodenticides seemed to be inefficient in controlling mice on this farm, susceptibility of these mice to anticoagulants has been characterized by Vkorc1 sequencing. 50% of the trapped mice carried mutations in the Vkorc1 gene leading to severe resistance to first-generation anticoagulants. The management of such mice that are a real sanitary threat can be achieved only by using the most toxic second-generation anticoagulants or nonanticoagulant solutions

Poisoning by Anticoagulant Rodenticides in Humans and Animals: Causes and Consequences

Anticoagulant rodenticides (ARs) are a keystone of the management of rodent populations in the world. The widespread use of these molecules raises questions on exposure and intoxication risks, which define the safety of these products. Exposures and intoxications can affect humans, domestic animals and wildlife. Consequences are different for each group, from the simple issue of intoxication in humans to public health concern if farm animals are exposed. After a rapid presentation of the mechanism of action and the use of anticoagulant rodenticides, this chapter assesses the prominence of poisoning by anticoagulant rodenticides in humans, domestic animals and wildlife

Establishment of the Variation of Vitamin K Status According to Vkorc1 Point Mutations Using Rat Models

International audienceVitamin K is crucial for many physiological processes such as coagulation, energy metabolism, and arterial calcification prevention due to its involvement in the activation of several vitamin K-dependent proteins. During this activation, vitamin K is converted into vitamin K epoxide, which must be re-reduced by the VKORC1 enzyme. Various VKORC1 mutations have been described in humans. While these mutations have been widely associated with anticoagulant resistance, their association with a modification of vitamin K status due to a modification of the enzyme efficiency has never been considered. Using animal models with different Vkorc1 mutations receiving a standard diet or a menadione-deficient diet, we investigated this association by measuring different markers of the vitamin K status. Each mutation dramatically affected vitamin K recycling efficiency. This decrease in recycling was associated with a significant alteration of the vitamin K status, even when animals were fed a menadione-enriched diet suggesting a loss of vitamin K from the cycle due to the presence of the Vkorc1 mutation. This change in vitamin K status resulted in clinical modifications in mutated rats only when animals receive a limited vitamin K intake totally consistent with the capacity of each strain to recycle vitamin K

Les Monooxygénases à Flavine (clonage, séquençage, caractérisation et étude de la distribution tissulaire chez le rat et le chien)

En présence de NADPH et d'oxygène moléculaire, les flavines monooxygénases (FMOs) catalysent l'oxydation de nombreux xénobiotiques azotés, phosphorés ou soufrés. La famille des FMOs est composée d'au moins cinq gènes codant cinq isoformes décrites jusqu'à présent que chez le lapin et l'homme. Ce travail rapporte la purification des isoformes 1 et 3 chez le mouton, ainsi que le clonage, le séquençage, et l'étude de la distribution tissulaire des FMOs 1 et 3, chez le chien et des FMOs 2, 3, 4 et 5, chez le rat. Cette étude confirme l'existence des isoformes FMO1 et FMO3 dans le foie de ces espèces animales. La régulation de l'expression des isoformes FMO1 et FMO3, chez le rat, a été observée par RT-PCR semi-quantitative et western blot. Leurs expressions hépatiques et rénales sont très largement influencées par l'acquisition de la maturité sexuelle chez le mâle comme chez la femelle. Sachant que la FMO1 avait été auparavant séquencée, cette étude a permis la caractérisation, chez le rat, des quatre autres isoformes. En raison d'une double délétion nucléotidique, la FMO2 du rat est, comme chez l'homme, tronquée et composée que de 432 acides aminés et non de 535. Malgré cette anomalie, la protéine FMO2 est exprimée, bien que très faiblement, dans le poumon du rat. La FMO4 a été séquencée à partir du rein et du cerveau. Deux transcrits différents ont été identifiés, un transcrit long et un transcrit court issu de l'épissage d'une région interne de 189 paires de bases. Cet épissage alternatif semble spécifique du cerveau. L'expression du variant FMO4 long a été démontrée dans le rein, alors que dans le cerveau, seul le variant FMO4 court a été détecté. La FMO5 a été séquencée à partir du foie du rat. Elle apparaît relativement similaire aux autres FMO5s orthologues. De nombreux tissus, le foie, le rein et les organes stéroïdo-formateurs expriment ce transcrit. Par contre l'expression de la protéine correspondante n'a été repérée que dans le foie.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

The stereoisomerism of second generation anticoagulant rodenticides - a way to improve this class of molecules to meet the requirements of society ?

International audienceSecond generation anticoagulant rodenticides (SGAR) are generally highly efficient for rodent management even towards warfarin-resistant rodents. Nevertheless, because of their long tissue-persistence, they are very associated with non-target exposure of wildlife and have been identified as 'Candidates for Substitution' by the European Union's competent authority. A promising way to reduce ecotoxicity issues associated to SGAR could be the improvement of SGAR based on their stereoisomery, and due to this improvement, positioning about SGAR might be reconsidered

Stereochemistry: a tool to modify pharmacokinetics properties of anticoagulant rodenticides without modifying their efficiency

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Enantiomeric fraction evaluation of the four stereoisomers of difethialone in biological matrices of rat by two enantioselective liquid chromatography tandem mass spectrometry methods: Chiral stationary phase or derivatization

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