La vitamine K est reconnue pour son rôle dans la coagulation sanguine. Les apports alimentaires de cette vitamine influencent la stabilité de l’anticoagulothérapie à la warfarine sodique. Une intervention visant à augmenter de ≥ 150 μg/j les apports alimentaires de vitamine K a été développée au sein du laboratoire de Guylaine Ferland. Les données préliminaires d’un essai clinique randomisé contrôlé de 24 semaines ont montré que les participants ayant suivi la stratégie alimentaire portant sur la vitamine K ont présenté une anticoagulothérapie plus stable, comparativement aux participants du groupe témoin. Cette stratégie a été décrite afin de fournir les informations nécessaires à son application en pratique clinique. Les anticoagulants demeurent des piliers dans la prévention des évènements thrombotiques notamment chez certaines personnes atteintes de maladies cardiovasculaires (MCV). Parmi les MCV, les maladies du coeur [particulièrement la maladie coronarienne (MC)] sont les plus répandues. La MC peut accélérer le développement de troubles cognitifs avec l’âge, et ce déclin cognitif relève en grande partie de l’atteinte vasculaire sous-jacente. La vitamine K constitue un nutriment d’intérêt pour le système vasculaire et la cognition au cours du vieillissement et aurait le potentiel d'atténuer les effets néfastes de la MC sur le cerveau. Une étude pilote d’intervention de 12 semaines examinant l’impact d’un supplément de 500 μg/j de vitamine K sur les fonctions cognitives et vasculaires d’individus atteints de MC stable a été développée. Ce projet a été implanté à l’Institut de Cardiologie de Montréal en mai 2022, et à ce jour, quatre participants ont complété l’intervention. À terme, cette étude permettra d’obtenir une évaluation préliminaire des bénéfices associés à la supplémentation de vitamine K sur la cognition et à recueillir des preuves suffisantes justifiant la planification d’une étude de plus grande envergure au sein de cette population. / Vitamin K is known for its role in blood coagulation. Dietary intakes of this vitamin influence the stability of warfarin anticoagulation therapy. An intervention aiming to increase dietary vitamin K intakes by ≥ 150 μg/d was developed in Guylaine Ferland's laboratory. Preliminary data from a 24-week randomized controlled trial showed that participants who followed the vitamin K dietary strategy had more stable anticoagulation therapy compared to participants in the control group. This strategy was described to provide the necessary information for its application in clinical practice. Anticoagulants remain mainstays in the prevention of thrombotic events notably in certain people with cardiovascular disease (CVD). Among CVD, heart disease [particularly coronary heart disease (CHD)] is the most prevalent. Coronary heart disease can accelerate the development of cognitive impairment with age, and this cognitive decline is largely a consequence of the underlying vascular impairment. Vitamin K is a nutrient of interest for the vascular and nervous systems during aging, and has the potential to mitigate the adverse effects of CHD on the brain. A 12-week pilot study examining the impact of a 500 μg/d vitamin K supplement on cognitive and vascular functions in individuals with stable CHD was developed. This project was implemented at the Montreal Heart Institute in May 2022, and to date, four participants have completed the intervention. This study will provide a preliminary assessment of the benefits associated with vitamin K supplementation on cognition and provide sufficient evidence to justify the planning of a larger study in this population.

Les déficiences en vitamines liposolubles sont fréquentes chez les patients atteints de la fibrose kystique (FK), mais la fréquence et les implications cliniques d’un déficit en vitamine K sont peu documentées. L’objectif de cette étude était d’évaluer les déficiences en vitamines liposolubles des patients adultes atteints de la FK et d’examiner les associations entre la concentration sérique de la vitamine K1 et le statut nutritionnel, la fonction pulmonaire et la tolérance au glucose. Nous avons effectué une étude transversale chez des patients adultes (≥ 18 ans, n =168) atteints de la FK. Les concentrations sériques de vitamine K1 ont été mesurées par chromatographie liquide à haute performance (HPLC) sur les prélèvements à jeun, obtenus lors du test d’hyperglycémie provoquée par voie orale (HPGO) visant à dépister le diabète associé à la FK. Les patients ont été classés selon leur taux de vitamine K1 (sous-optimal défini comme < 0,30 nmol/L). Des taux sanguins sous-optimaux de vitamine K1 ont été observés chez 66 % des patients atteints de la FK. Les patients ayant un statut sous-optimal en vitamine K1 ont un risque plus élevé de colonisation par la bactérie Pseudomonas aeruginosa, un indice de masse corporelle (IMC) plus bas et sont plus susceptibles d'avoir une insuffisance pancréatique exocrine. Une régression multivariée n'a pas réussi à démontrer des relations significatives entre les variables cliniques et les niveaux de vitamine K1 transformés en log. En utilisant un seuil pour la vitamine K1, nous avons montré des mesures réduites de la sécrétion d'insuline chez les patients ayant un statut en vitamine K1 inférieur à 0,30 nmol/L. Une association claire entre un statut sous-optimal en vitamine K1 et les mesures de la dysglycémie et de la sécrétion d'insuline n’a pas pu être démontrée. Nous soulignons les associations potentielles d'une carence légère en vitamine K avec une colonisation par la bactérie Pseudomonas et un IMC plus bas, bien que celles-ci doivent être validées dans des études prospectives. Ce mémoire contribue à l’amélioration des connaissances sur le statut en vitamine K chez les adultes atteints de la FK. / Patients with Cystic Fibrosis (CF) are at high risk of fat-soluble vitamin deficiencies, even with supplementation. The contribution of fat-soluble deficiencies to respiratory and endocrine pathophysiology in CF has been inadequately characterized. The aim of this observational study was to assess vitamin deficiencies in adult patients with CF, in the Montreal Cystic Fibrosis Cohort (MCFC). In particular, given the lack of evidence around the impact of vitamin K in CF, the purpose was to look at how vitamin K1 related to CF-related diabetes (CFRD) and whether there was a negative association between a suboptimal vitamin K1 status and measures of dysglycemia. We performed a cross-sectional study with baseline data from adult patients with CF (≥ 18 years old, n = 168). Serum vitamin K1 was measured with high performance liquid chromatography (HPLC) on fasting samples from an oral glucose tolerance test (OGTT) used for CFRD screening. Patients were categorized according to vitamin K levels (suboptimal defined as <0.30 nmol/L). Suboptimal vitamin K1 levels were observed in 66 % of patients. Patients with a suboptimal vitamin K1 status have a higher risk of colonization with Pseudomonas aeruginosa, lower BMI and were more likely to have exocrine pancreatic insufficiency. Multivariate regression failed to demonstrate significant relationships between clinical variables and log-transformed vitamin K1 levels. Using an established threshold for vitamin K1, we did show reduced OGTT-derived measures of insulin secretion in patients with a vitamin K1 status below 0.30 nmol/L. We failed to demonstrate a clear association between a suboptimal vitamin K status and measures of dysglycemia and insulin secretion. We highlight the potential associations of mild vitamin K deficiency with pseudomonal colonization and lower BMI, although these need to be validated in prospective studies. This study contributes to improving knowledge on vitamin K status in patients with CF.

No / Potential protective effects of the flavonoids quercetin and luteolin have been examined against the oxidative stress of MC3T3-E1 osteoblast-like cells. Although hydrogen peroxide and menadione reduced cell viability, the toxicity was prevented by desferrioxamine or catalase but not superoxide dismutase, suggesting the involvement of hydrogen peroxide in both cases. Quercetin and luteolin reduced the oxidative damage, especially that caused by hydrogen peroxide. When cultures were pre-incubated with quercetin or luteolin, protection was reduced or lost. Protection was also reduced when a 24 h pre-incubation with the flavonoids was followed by exposure to menadione alone. Pretreating cultures with luteolin impaired protection by quercetin, whereas quercetin pretreatment did not affect protection by luteolin. It is concluded that quercetin and luteolin suppress oxidative damage to MC3T3-E1 cells, especially caused by peroxide. The reduction in protection by pretreatment implies a down-regulation of part of the toxic transduction pathway.

Background: Warfarin is an anticoagulant that is used for the prophylactic and therapeutic treatment for a wide range of thrombo-embolic disorders. The prescribing and monitoring of warfarin therapy is challenging due to the fact that warfarin exhibits numerous interactions with other drugs and a variety of factors that influence the dosing of warfarin. Objective: The general objective of this study was to investigate the prevalence of drugs prescribed with warfarin that may have a potential drug-drug interaction (DDI) with warfarin. Methods: This was a cross-sectional, observational or qualitative study that was conducted on medicine claims data of a pharmaceutical benefit management company for patients receiving warfarin therapy for a six year period, ranging from 1 January 2005 to 31 December 2010. Drug products that were co-prescribed with warfarin were also identified from the medicine claims database. The total number of prescriptions for all drug products during the study period were analysed and compared to the warfarin dataset. This was done by means of the SAS 9.1® computer package (SAS Institute, 2004). The total number of prescriptions and medicine items claimed from the database during the study period were respectively 49 523 818 and 118 305 941. Potential DDls between warfarin and coprescribed drugs were identified and classified according to a clinically significant rating. The clinically significance ratings of potential DDls are described in three degrees of severity, identified as major, moderate and minor (Tatro, 2011 :xiv). Results: The database consisted of 427 238 warfarin prescriptions and 427 744 warfarin medicine items, which represented 0.9% of the total number of prescriptions and 0.4% of total number of medicine items. The total number of patients who claimed warfarin prescriptions through the database represented 0.9% (n=68 575) of the total number of patients who claimed prescriptions in the total database (2005-2010). General practitioners prescribed the highest frequency of warfarin medicine items, representing 58.3% (n=249 202) of the total number prescribed. The age group that claimed the highest frequency of warfarin prescriptions (n=327 592, 76.6%) and the highest frequency of warfarin medicine items (n=327 984, 76.7%) was age group 4 (consisting of patients 59 years and older). The distribution between females and males regarding warfarin prescriptions claimed (n=205 999, 48.2%; n=221 117, 51.8%) and warfarin medicine items claimed (n=206 232, 48.2%; n=221 390, 51.8%) were almost equal. General practitioners prescribed the highest average PDD (7.01 mg ± 9.86 mg) of warfarin medicine items. Paediatric cardiologists prescribed the lowest average PDD (4.61 mg ± 1.29 mg) of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDD between general practitioners and paediatric cardiologists. The average PDD of warfarin medicine items between females (6.60 mg ± 9.06 mg) and males (6.74 mg± 8.41 mg) was almost equal. The age group who was prescribed the highest average PDD was age group 2 (consisting of patients 20 years to 39 years old) (7.42 mg± 7.42 mg). Age group 4 (consisting of patients 59 years and older) (6.50 mg± 8.90 mg) was prescribed the lowest average PDD of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDDs of warfarin medicine items between these two age groups. The results revealed that drugs with a significance rating (SR) of 1 (n=155 066, 43.3%), 2 (n=30128, 8.4%), 4 (n=137144, 38.3%), and 5 (n=36144, 10.1%) were co-prescribed with warfarin in the six year study period. The five drugs that was co-prescribed with warfarin most frequently was aspirin (n=48 903, 13.6%), thyroxine (n=33 954, 9.5%), amiodarone (n=25 056, 7.0%), simvastatin (n=19 070, 5.3%) and celecoxib (n=10 794, 3.0%). These five drugs have a SR of 1. Conclusions: This study showed that the top five drugs most frequently prescribed with warfarin are aspirin, thyroxine, amiodarone, simvastatin and celecoxib. These drugs can potentially interact with warfarin. The potential interactions of these drugs are rated with a significance rating of 1. This concludes that drugs that can potentially cause life threatening effects and permanent damage are commonly co-prescribed with warfarin. Clinical data concerning the INR or PT must be obtained in order to evaluate whether or not warfarin therapy is changed when a potentially interacting drug is co-prescribed. The age of the patients as well as the duration of warfarin treatment should also be obtained in order to assess whether warfarin treatment is changed with the progression of age. / MPharm (Pharmacy Practice), North-West University, Potchefstroom Campus, 2013

Background: Warfarin is an anticoagulant that is used for the prophylactic and therapeutic treatment for a wide range of thrombo-embolic disorders. The prescribing and monitoring of warfarin therapy is challenging due to the fact that warfarin exhibits numerous interactions with other drugs and a variety of factors that influence the dosing of warfarin. Objective: The general objective of this study was to investigate the prevalence of drugs prescribed with warfarin that may have a potential drug-drug interaction (DDI) with warfarin. Methods: This was a cross-sectional, observational or qualitative study that was conducted on medicine claims data of a pharmaceutical benefit management company for patients receiving warfarin therapy for a six year period, ranging from 1 January 2005 to 31 December 2010. Drug products that were co-prescribed with warfarin were also identified from the medicine claims database. The total number of prescriptions for all drug products during the study period were analysed and compared to the warfarin dataset. This was done by means of the SAS 9.1® computer package (SAS Institute, 2004). The total number of prescriptions and medicine items claimed from the database during the study period were respectively 49 523 818 and 118 305 941. Potential DDls between warfarin and coprescribed drugs were identified and classified according to a clinically significant rating. The clinically significance ratings of potential DDls are described in three degrees of severity, identified as major, moderate and minor (Tatro, 2011 :xiv). Results: The database consisted of 427 238 warfarin prescriptions and 427 744 warfarin medicine items, which represented 0.9% of the total number of prescriptions and 0.4% of total number of medicine items. The total number of patients who claimed warfarin prescriptions through the database represented 0.9% (n=68 575) of the total number of patients who claimed prescriptions in the total database (2005-2010). General practitioners prescribed the highest frequency of warfarin medicine items, representing 58.3% (n=249 202) of the total number prescribed. The age group that claimed the highest frequency of warfarin prescriptions (n=327 592, 76.6%) and the highest frequency of warfarin medicine items (n=327 984, 76.7%) was age group 4 (consisting of patients 59 years and older). The distribution between females and males regarding warfarin prescriptions claimed (n=205 999, 48.2%; n=221 117, 51.8%) and warfarin medicine items claimed (n=206 232, 48.2%; n=221 390, 51.8%) were almost equal. General practitioners prescribed the highest average PDD (7.01 mg ± 9.86 mg) of warfarin medicine items. Paediatric cardiologists prescribed the lowest average PDD (4.61 mg ± 1.29 mg) of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDD between general practitioners and paediatric cardiologists. The average PDD of warfarin medicine items between females (6.60 mg ± 9.06 mg) and males (6.74 mg± 8.41 mg) was almost equal. The age group who was prescribed the highest average PDD was age group 2 (consisting of patients 20 years to 39 years old) (7.42 mg± 7.42 mg). Age group 4 (consisting of patients 59 years and older) (6.50 mg± 8.90 mg) was prescribed the lowest average PDD of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDDs of warfarin medicine items between these two age groups. The results revealed that drugs with a significance rating (SR) of 1 (n=155 066, 43.3%), 2 (n=30128, 8.4%), 4 (n=137144, 38.3%), and 5 (n=36144, 10.1%) were co-prescribed with warfarin in the six year study period. The five drugs that was co-prescribed with warfarin most frequently was aspirin (n=48 903, 13.6%), thyroxine (n=33 954, 9.5%), amiodarone (n=25 056, 7.0%), simvastatin (n=19 070, 5.3%) and celecoxib (n=10 794, 3.0%). These five drugs have a SR of 1. Conclusions: This study showed that the top five drugs most frequently prescribed with warfarin are aspirin, thyroxine, amiodarone, simvastatin and celecoxib. These drugs can potentially interact with warfarin. The potential interactions of these drugs are rated with a significance rating of 1. This concludes that drugs that can potentially cause life threatening effects and permanent damage are commonly co-prescribed with warfarin. Clinical data concerning the INR or PT must be obtained in order to evaluate whether or not warfarin therapy is changed when a potentially interacting drug is co-prescribed. The age of the patients as well as the duration of warfarin treatment should also be obtained in order to assess whether warfarin treatment is changed with the progression of age. / MPharm (Pharmacy Practice), North-West University, Potchefstroom Campus, 2013

De plus en plus d’études montrent un lien entre la teneur en vitamine K (VK) dans l’organisme et la cognition. Certaines études effectuées in vitro on montré l’effet de la VK au niveau moléculaire, mais très peu in vivo. Une étude récente de Tamadon-Nejad a montré qu’un traitement de 14mg/kg/jr de warfarine, un antagoniste de la VK, administré simultanément à des injections sous-cutanées de 85mg/kg/jr de phylloquinone entrainait une diminution significative de la concentration de MK-4 du cerveau, résultant en une diminution significative du statut vitaminique K au cerveau, une altération de la cognition, du comportement exploratoire et de la locomotion [1]. Dans la présente étude, le traitement de Tamadon-Nejad a été modifié et les doses de phylloquinone ont été augmentées à 120mg/kg/jr (WVK) ce qui a maintenu une diminution significative de la concentration de la concentration de MK-4 dans le cerveau, mais a entrainé une surcompensation par la phylloquinone, résultant en une augmentation significative du statut vitaminique K au cerveau. Ce statut a été associé à une mémoire de reconnaissance intacte et corrélé à une amélioration de la mémoire spatiale des rats WVK. Le traitement a aussi été associé à une augmentation significative de l’anxiété et au rétablissement du comportement exploratoire et de la locomotion des rats WVK comparativement à l’étude de Tamadon-Nejad [1]. Dans l’hippocampe des rats WVK, l’amélioration de la cognition et le rehaussement du statut vitaminique K du cerveau n'ont pas induit de variation significative de l’activation des protéines dépendantes de la VK Gas6 et Protéine S, mais ont été associés à une augmentation significative de l’activation de la voie MAPK, à une inhibition de l’apoptose et à une présence accrue de la microglie. En somme, cette étude confirme le rôle modulateur de la VK dans le cerveau sur la cognition et la survie cellulaire. / There is growing evidence that vitamin K (VK) plays a role in cognition. Some in vitro studies have shown how VK affects different molecular pathways in brain cells, but few in vivo studies have been conducted. Recently, a study from Tamadon- Nejad showed that a treatment of 14mg/kg/d of warfarine, a VK antagonist, given simultaneously with subcutaneous injections of 85mg/kg/d lead to a significant decrease in MK-4 concentration in brain, resulting in a significant decrease of VK status in brain, and perturbation in cognition, exploratory behaviour and locomotion [1]. In the present study, we modified the treatment used in Tamadon-Nejad and increased the phylloquinone doses to 120mg/kg/d which maintained the significant decrease in MK-4 concentration in brain, but lead to an overcompensation of phylloquinone that resulted in an increase of VK status in brain. This status was associated with an intact recognition memory and correlated with an improvement in spatial memory of WVK rats. The treatment was also associated with a significant increase in anxiety and recovery of exploratory behavior and locomotion compared to rats in the Tamadon-Nejad study [1]. In WVK rat hippocampi, cognition improvement and increased VK status were not associated with significant variation in VK dependant proteins (VKDP) Gas6 and Protein S activation, but were associated with an increase in the MAPK activation pathway, an inhibition of apoptosis and, an increased presence of microglia. In summary, this study confirms the modulatory role of VK in brain in cognition and cell survival.

En France, depuis 2012, les anticoagulants oraux directs (AOD), indiqués dans la prévention des accidents vasculaires cérébraux chez les patients avec fibrillation auriculaire (FA) non valvulaire, sont une alternative aux antivitamines K (AVK) pour lesquels une sous-prescription et un défaut d’observance ont été largement décrits. L’objectif de cette thèse était, dans le cadre du programme de travail du Département études de santé publique de la Caisse nationale de l’Assurance maladie, d’étudier à partir des bases de données médico-administratives (BDMA) françaises l’utilisation et la sécurité du traitement anticoagulant oral (ACO) en situation réelle de soins chez les patients avec FA. Un premier travail a permis de construire un algorithme pour identifier l’indication FA chez les patients débutant un ACO et pour lesquels aucun diagnostic de FA n’était retrouvé dans les BDMA. Un deuxième travail a porté sur l’évaluation de l’adhésion au traitement ACO chez les nouveaux utilisateurs : au cours de l’année suivant l’initiation du traitement, au moins un patient sur trois arrêtait son traitement, dabigatran ou rivaroxaban, et la persistance à ces traitements n’était pas meilleure que celle des AVK. Un troisième travail a décrit une amélioration de la couverture anticoagulante chez les patients avec FA entre 2011 et 2016. Cependant, un patient sur trois était encore sans traitement ACO en 2016 et de potentiels mésusages à l’instauration du traitement AOD ont été identifiés, dont un signal de sous-dosage. Enfin, une analyse en symétrie de séquences a suggéré que l’initiation des AOD serait associée à la survenue rare d’atteintes toxiques aiguës du foie et à la survenue plus fréquente de troubles gastrointestinaux. Avec la description de la population et de l’utilisation rejointes des traitements ACO en France chez les patients avec FA, ces résultats encouragent la poursuite de la surveillance des effets indésirables non hémorragiques des AOD et l’amélioration de leur utilisation. / Direct oral anticoagulants (DOAC) were gradually introduced since 2012 in France for stroke and systemic embolism prevention in patients with nonvalvular atrial fibrillation (AF), as a more convenient alternative to vitamin K antagonists (VKA) for which underprescribing and high rates of discontinuation have been frequently reported. As part of the work programme of the Department of Studies in Public Health, French National Health Insurance, the aim of this dissertation was to assess the patterns of use and safety of oral anticoagulant (OAC) therapy in real-life setting using the French healthcare databases. First, an algorithm was developed to identify AF in outpatients initiating OAC and for whom no diagnosis of AF was found in the French claims data. Second, 1-year dabigatran and rivaroxaban adherence rates were estimated in nonvalvular AF patients and 1-year non-persistence rates were compared versus VKA. At least 1 in 3 dabigatran or rivaroxaban new users was found to be non-adherent to treatment. Treatment persistence among dabigatran or rivaroxaban new users was not found to be better versus VKA therapy. Third, OAC therapy use was found to have increased following in France between 2011 and 2016 but remained suboptimal with 1 in 3 patients with AF not treated by OAC therapy. Several situations of inappropriate use of DOAC were identified including potential undertreatment by inappropriate dosing. Finally, a sequence symmetry analysis suggested that DOAC therapy is associated with rare but severe liver injury and more frequent gastrointestinal disorders. A low risk of kidney injury with DOAC therapy can also not be excluded. These findings advocate further investigation of the potential risk of DOAC underdosing at initiation and the continuous monitoring of the non-bleeding adverse events of DOAC therapy.

A ce jour, les anticoagulants commerciaux souffrent de deux inconvénients majeurs : leur rémanence avec, pour certains d’entre eux, une demi-vie hépatique proche des 300 jours causant des intoxications secondaires sur les prédateurs des rongeurs, ainsi que le développement de nombreuses mutations génétiques causé par l’utilisation intensive de ces composés, rendant inopérant l’utilisation de certains AVKs commerciaux. Face à ce constat, l’Union Européenne envisage d’interdire l’utilisation de tels composés. La mission prioritaire est donc de trouver un anticoagulant capable de gérer les populations de rongeurs sans affecter leurs prédateurs. Les recherches mises en avant par Adrien Montagut (Thèse 2011-2014) ont permis d’aboutir à une structure type d’anticoagulants, dérivés de la 4-hydroxycoumarine. Actuellement, AMR361 a été testé in vitro sur l’ensemble des mutations de VKORC1 et in vivo sur rats sauvages, et constitue le premier AVK développé qui répond à l’ensemble des caractéristiques du cahier des charges initial. La première partie de mon projet de thèse consistait à compléter l’étude biologique sur le noyau 4-hydroxycoumarine en amenant de la diversité fonctionnelle sur la position para du noyau aromatique. D’un point de vue biologique, l’allongement du bras espaceur sur la chaîne latérale par l’utilisation de fonctions telles que les amides ou amides inversés ou l’introduction d’un groupement diméthyle sur le pont méthylène ont été étudiés afin d’analyser les paramètres d’efficacité et de rémanence. Cependant, la plupart des composés synthétisés appartenant à la famille des 4-hydroxycoumarines font déjà l’objet d’un brevet déposé par l’entreprise Liphatech en 1999. L’étude de nouveaux noyaux, dont certains sont analogues à la 4-hydroxycoumarine, de même que la fonctionnalisation du noyau 4-hydroxycoumarine sur la partie aromatique, a permis l’accès à des structures plus diverses. Ces perspectives originales pour l’innovation ont été introduites pour contourner les brevets déjà existants. / To date, commercial anticoagulants suffer from two major inconveniences: their persistence causing secondary poisoning of rodent predators and the development of many genetic mutations caused by the intensive use of these compounds. As a result, the European Union plans to prohibit the use of such compounds. Consequently, the priority task is to find an anticoagulant that can control the rodent populations without affecting their predators. The research of Dr. Adrien Montagut (PhD, 2011-2014) have led to the structure type of an anticoagulant derived from 4-hydroxycoumarin. Currently, AMR361 was tested in vitro on all VKORC1 mutations and in vivo on wild rats. It is the first AVK developed that responds to all the characteristics of the initial specification. The first part of my PhD was to complete the biological study on 4-hydroxycoumarin core by bringing functional diversity on the para position of the aromatic ring. From a biological point of view, the lengthening of the spacer arm on the side chain by use of various functions or the introduction of a dimethyl group on the methylene bridge were studied in order to analyze the effectiveness and persistence parameters. However, most of the synthesized compounds belonging to the family of 4-hydroxycoumarins are already described in a patent filed by Liphatech company in 1999. The study of new cores which are similar to the 4-hydroxycoumarin or the functionalization of the aromatic part of the 4-hydroxycoumarin has provided access to more diverse structures. These original possibilities for innovation have been introduced to circumvent existing patents.

Les anticoagulants antivitamine K (AVK) sont destinées à limiter la coagulation du sang. Ils sont donc susceptibles de provoquer des saignements. Les AVK ralentissent le cycle de la vitamine K qui est indispensable à la gamma-carboxylation de certaines protéines (PVKD). Les AVK inhibent l'activité vitamine K époxide reductase (VKOR), principalement catalysée par VKORC1. Ce sont des médicaments anticoagulants utilisés chez l'homme. Chez les rongeurs, ils servent de rodonticides. Une résistance aux AVK est observé tant chez l'homme que chez le rongeur.Chez des patients résistants aux AVK, 26 mutations ont été décrites dans la zone codante de VKORC1. L'expression hétérologue de ces enzymes mutées n'a permis de trouver que 6 mutations impliquées dans la résistance. Repérer ces mutations avant le début d'un traitement permettra une mise en place du traitement plus rapide. Les autres mutations ne seraient pas responsables du phénotype observé.La VKORC1L1 a été décrite comme une protéine agissant contre le stress oxydatif. Notre travail confirme que l'enzyme catalyse la réaction VKOR. Si sa participation dans la réduction de la vitamine K époxide est insignifiante dans le foie, il en est tout autrement dans les autres tissus testés. De plus, la VKORC1L1 apparait plus résistante aux AVK par rapport à la VKORC1. Ces propriétés catalytiques de la VKORC1L1 permettent d'expliquer l'absence d'effets des AVK sur les PVKD d'origine extra-hépatiques.Enfin, un travail de mutagénèse dirigée a permis d'abaisser ou d'augmenter considérablement la sensibilité de VKORC1L1 aux AVK. Ces résultats nous permettent de décrire l'implication de différents acides aminés dans l'interaction avec les AVK / Anticoagulant vitamin K antagonists (VKA) are molecules designed to prevent or delay blood clotting. They cause bleeding by slowing the recycling of vitamin K, an essential micronutrient for posttranslational modification of specific proteins (VKDP). It has been shown that VKA specifically inhibit VKORC1 enzyme which catalyze the VKOR reaction. VKA are used as rodenticides to control the proliferation of populations of pest rodents. In humans, they are used in the treatment and prevention of the occurrence of thromboembolic events. Due to the widespread use of these VKA, it was observed a phenomenon of resistance which is essential to better understand for economic, ecological or public health interests. In humans, 25 of 26 mutations were characterized. While these changes have been observed in patients resistant to VKA, the causality of these mutations has been demonstrated for 6 mutations. The ability to detect these changes before the start of treatment will allow the future implementation of the much faster and less expensive. Other mutations are not responsible for the observed phenotype.Moreover, VKORC1L1 has been described as an enzyme whose function is to act against oxidative stress. This study confirms that the enzyme catalyzes the VKOR reaction. If it appears that the liver in its participation in the reduction of vitamin K epoxide is insignificant, it is quite different in other tissues tested. In addition, VKORC1L1 appears more resistant to VKA over the VKORC1. Finally, directed mutagenesis of these residues lead to the decrease or the increase of VKORC1L1 sensitivity to VKA. These data result to the implication of residues in their interaction with VKA

Venous thromboembolism that cause blood clotting in blood vessels, prevent blood circulation, depending on changes in one or more of the coagulation factors II, VII, IX and X. Patients who have had a blood clot or cardiovascular diseases are treated with oral anti-vitamin K (Warfarin®) to reducing and prevent relapse. Warfarin is also used as a preventive treatment before the disease. An overdose of Warfarin® may cause bleeding-complications and low dose cause blood clotting. The dosage of the drug is controlled by measuring prothrombin in plasma. The aim of this study was to investigate if prothrombin-complex value changes due to re-spinning and re-analysis after six hours. Fitty whole blood samples from warfarin-treated patients were divided into three subgroups, those with protrombinkomplex-values of 2-4 (n=20), &gt;4 (n=15) and &lt;2 (n=15). The samples were centrifugated and measured (Method A), re-centrifugated and measured (Method B) or re-analysed after six hours (Method C). All results were compared in a Bland-Altman plot as follows: Method B vs. Method A and Method C vs. Method A. The scatter graph yielded a strong correlation between Method A and Method B (R2=0.9984) and Method A and Methods C (R2=0.9977). The results from t-test showed a significance level (p&lt;0.001) for both analyses (statistical significance=p&lt;0.05). In this study we showed that prothrombin complex value ware stable after re-centrifugation and re-measurement after six hours. Statistical calculations yielded a strong correlation between the methods (A, B, C), and there was no significance difference between the methods.