INTRODUÇÃO. Estudos epidemiológicos têm demonstrado que a exposição à poluição atmosférica está associada ao aumento de doenças cardiorrespiratórias. Trabalhos experimentais anteriores, utilizaram uretana para induzir a formação de nódulos pulmonares em camundongos e expor estes animais à poluição de \"mundo real\". Ou seja, os animais foram expostos a gases e partículas da mesma forma com que a população está exposta na cidade de São Paulo. Evidenciou-se então, o papel promotor e dose dependente da atmosfera poluída na progressão dos tumores de pulmão. Sabe-se que substâncias carcinogênicas como hidrocarbonetos policíclicos aromáticos (HPA), metais, ácidos graxos e aldeídos, estão presentes na fração particulada respirável da poluição (material particulado fino - MP 2,5), e a exposição prolongada a este último vem sendo considerada um risco para o desenvolvimento do câncer de pulmão. O objetivo deste estudo é verificar se a exposição crônica ao MP2,5 concentrado, a partir do ar ambiente da cidade de São Paulo, tem potencial carcinogênico. MÉTODOS. Foram utilizados 60 camundongos machos suíços (30g); e 60 AJ (20g), com quatro a seis semanas de vida. Os camundongos suíços foram pré-tratados com um carcinógeno completo, o ácido carbâmico (uretana-U), enquanto que os AJ receberam um carcinógeno iniciador 4-(methylnitrosamino)-1-(3-pyridil)-1-butanona (NNK), por serem pré-dispostos ao desenvolvimento de tumores de pulmão. Em seguida todos os animais foram expostos no Concentrador de Partículas Atmosféricas Harvard ao MP 2,5 diariamente, por 2 horas, durante quatro meses. Cada linhagem foi dividida em quatro grupos (n=15 cada): 2 controles com salina e carcinógeno (CsS e CsU ou CajS e CajNNK) e 2 expostos com salina e carcinógeno (EsS e EsU ou EajS e EajNNK). Foi realizada a análise histopatológica dos pulmões, a contagem e classificação das lesões pulmonares encontradas. Foi feito estudo imunoistoquimico para p53 e PCNA. RESULTADOS. Os animais dos grupos expostos, em ambas as linhagens, apresentaram maior número de lesões neoplásicas. As médias de lesões (nódulos e hiperplasia) obtidas foram: CsU: 1,07( DP+ 1,54), CsSl: 0( DP+ 0), EsU: 2,57 ( DP+ 2,77) e EsS: 0,40 ( DP+ 1,12), com p < 0,001; CajNNK: 4,94( DP+ 3,54), CajS: 0,15( DP+ 0,37), EajNNK: 9,14 ( DP+ 7,70) e EajS:0,80 ( DP+ 1,93), com p<0,001. Não houve alterações para o p53 em ambas as linhagens e, apenas os grupos AJ controle e exposto NNK apresentaram diferença para o PCNA. CONCLUSÃO. A exposição crônica ao MP 2,5 proveniente da poluição atmosférica da cidade de São Paulo tem potencial para promover tumores em camundongos de duas linhagens diferentes, com ou sem o pré-tratamento por carcinógenos / INTRODUCTION. Epidemiological studies have shown that exposure to air pollution is associated with increased cardiorespiratory diseases. Previous experimental studies, we used urethane to induce lung nodule formation in mice and these animals exposed to pollution from \"real world.\" In these studies, animals were exposed to gases and particles in the same way that the population is exposed in the city of São Paulo. It was evident then, the role of promoter and dose dependent polluted atmosphere in the progression of lung tumors. It is known that carcinogens such as polycyclic aromatic hydrocarbons (PAHs), metals, aldehydes and fatty acids, are present in the respirable fraction particulate pollution (fine particulate matter - PM2.5), and prolonged exposure to the latter has been considered a risk factor for the development of lung cancer. The objective of this study is to verify whether chronic exposure to PM 2.5 concentration from the air of the city of São Paulo, has carcinogenic potential. METHODS. A total of 60 male Swiss mice (30 g) and 60 AJ (20g), with four to six weeks of life. The Swiss mice were pretreated with a carcinogen completed, the carbamic acid (urethane-U), while AJ received a carcinogen primer 4 - (methylnitrosamino) -1 - (3-pyridil)-1-butanone (NNK) as being predisposed to developing lung tumors. Then all the animals were exposed to atmospheric Harvard Particle Concentrator to PM 2.5 daily for two hours for four months. Each strain was divided into four groups (n = 15 each): 2 with saline controls and carcinogen (CsS and CsU or CajS and CajNNK) and 2 exposed to saline and carcinogen (EsS and EsS or EajS and EajNNK). After the exposure time, the animals were anesthetized and euthanized. The lungs were fixed, processed histologically and imunohistochemistry was performed on slides with tumor presence of antibodies to p53 and PCNA. Later, in histopathology of pulmonary nodules made counting and classification of lesions found. RESULTS. The animals exposed groups in both strains showed a high percentage of neoplastic lesions. Mean lesions (nodules and hyperplasia) were obtained: CsU: 1.07 (SD + 1.54), CsS: 0 (DP + 0), EsU: 2.57 (SD + 2.77) and EsS: 0.40 ( + SD 1.12), p < 0.001; CajNNK: 4.94 (SD + 3.54), CajS: 0.15 (SD + 0.37), EajNNK: 9.14 (SD + 7.70) and EajS: 0 , 80 (SD + 1.93), with p < 0.001. There were no changes to the p53 in both strains, and only groups A / J control and exposed to NNK differ PCNA. CONCLUSION. The chronic exposure to PM 2.5 air pollution from the city of São Paulo has the potential to promote tumors in mice of two different strains with or without pretreatment by carcinogens

Thèse (Ph. D.)--Université Laval, 2007. / Titre de l'écran-titre (visionné le 18 sept. 2007). Bibliogr.

Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-01T13:42:01Z No. of bitstreams: 1 arquivototal.pdf: 3885187 bytes, checksum: 43a97495626de95064ede3adad23bcd9 (MD5) / Made available in DSpace on 2017-08-01T13:42:01Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3885187 bytes, checksum: 43a97495626de95064ede3adad23bcd9 (MD5) Previous issue date: 2016-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work we performed ωB97XD, CAM-B3LYP, CASSCF, MR-CISD, MRCISD+ Q and NEVPT2 calculations. The basis sets aug-cc-pVDZ and cc-pVTZ were used to assess the stability of certain neutral and protonated N-nitrosamines in the ground and excited states. In addition, we analyzed the effect of methylation on proton transfer. The initial proposal was to characterize the stationary points and the potential energy curves in the ground and excited state, in order to suggest a strategy that results in lower computational demand to be applied in larger systems (cyclic and bicyclic N-nitrosamines). The results indicate that the methodology MR-CISD/cc-pVTZ//MR-CISD/aug-cc-pVDZ may be appropriate to study the N-nitrosamines. The used functionals provided good descriptions to vertical excitation energy, but were not capable to represent the states correctly to dissociation curves. MR-CID+Q/cc-pVTZ results for the system (CH3)2NNO protonated indicate that protonation is more favorable for NDMA_1A, increasing energy in 17.5 kcal mol-1, and that the methylation significantly alter the intramolecular proton transfer barriers. With the aim to find a methodology with lower computational cost, use a reference wave function CASSCF (12, 9) at the level NEVPT2/cc-pVTZ was used study the neutral NDMA and results were consistent with both the theoretical and experimental parameters in the literature. For studies involving larger systems, for example, cyclic and bicyclic N-nitrosamines, NEVPT2 may be used, since it is completely paralyzed, and involves the use of a CASSCF larger than CAS (14, 10), which is a fundamental characteristic to study larger systems. / Neste trabalho foram realizados cálculos ωB97XD, CAM-B3LYP, CASSCF, MRCISD, MR-CISD+Q e NEVPT2. Os conjuntos de base aug-cc-pVDZ e cc-pVTZ foram usados para avaliar a estabilidade de algumas N-nitrosaminas neutras e protonadas nos estados fundamental e excitado. Além disso, foi analisado o efeito da metilação nas transferências de próton. A proposta inicial foi caracterizar os pontos estacionários, as curvas de energia potencial no estado fundamental e excitado, com a finalidade de sugerir uma estratégia que resulte em menor demanda computacional para ser aplicada em sistemas maiores (N-nitrosaminas cíclicas e bicíclicas). Os resultados indicaram que a metodologia MR-CISD/cc-pVTZ//MR-CISD/aug-cc-pVDZ pode ser adequada para estudar as N-nitrosaminas. Os funcionais utilizados forneceram boas descrições para a energia de excitação vertical, mas para as curvas de dissociação não foram capazes de representar os estados corretamente. Os resultados com MR-CISD+Q/cc-pVTZ para o sistema (CH3)2NNO protonado indicam que a protonação é mais favorável para NDMA_1A, aumentando a energia em 17,5 kcal mol-1, e que a metilação altera significativamente as barreiras de transferência de próton intramoleculares. Com a proposta de encontrar uma metodologia com menor custo computacional, utilizou-se uma função de onda de referência CASSCF (12, 9) a nível NEVPT2/cc-pVTZ para estudar a NDMA neutra e os resultados foram compatíveis com os parâmetros experimentais e teóricos existentes na literatura. Para estudos envolvendo sistemas maiores, por exemplo, N-nitrosaminas cíclicas e bicíclicas, NEVPT2 poderá ser usado, uma vez que está totalmente paralelizado e comporta a utilização de um CASSCF maior que CAS (14, 10), característica fundamental para estudar sistemas maiores.

INTRODUÇÃO. Estudos epidemiológicos têm demonstrado que a exposição à poluição atmosférica está associada ao aumento de doenças cardiorrespiratórias. Trabalhos experimentais anteriores, utilizaram uretana para induzir a formação de nódulos pulmonares em camundongos e expor estes animais à poluição de \"mundo real\". Ou seja, os animais foram expostos a gases e partículas da mesma forma com que a população está exposta na cidade de São Paulo. Evidenciou-se então, o papel promotor e dose dependente da atmosfera poluída na progressão dos tumores de pulmão. Sabe-se que substâncias carcinogênicas como hidrocarbonetos policíclicos aromáticos (HPA), metais, ácidos graxos e aldeídos, estão presentes na fração particulada respirável da poluição (material particulado fino - MP 2,5), e a exposição prolongada a este último vem sendo considerada um risco para o desenvolvimento do câncer de pulmão. O objetivo deste estudo é verificar se a exposição crônica ao MP2,5 concentrado, a partir do ar ambiente da cidade de São Paulo, tem potencial carcinogênico. MÉTODOS. Foram utilizados 60 camundongos machos suíços (30g); e 60 AJ (20g), com quatro a seis semanas de vida. Os camundongos suíços foram pré-tratados com um carcinógeno completo, o ácido carbâmico (uretana-U), enquanto que os AJ receberam um carcinógeno iniciador 4-(methylnitrosamino)-1-(3-pyridil)-1-butanona (NNK), por serem pré-dispostos ao desenvolvimento de tumores de pulmão. Em seguida todos os animais foram expostos no Concentrador de Partículas Atmosféricas Harvard ao MP 2,5 diariamente, por 2 horas, durante quatro meses. Cada linhagem foi dividida em quatro grupos (n=15 cada): 2 controles com salina e carcinógeno (CsS e CsU ou CajS e CajNNK) e 2 expostos com salina e carcinógeno (EsS e EsU ou EajS e EajNNK). Foi realizada a análise histopatológica dos pulmões, a contagem e classificação das lesões pulmonares encontradas. Foi feito estudo imunoistoquimico para p53 e PCNA. RESULTADOS. Os animais dos grupos expostos, em ambas as linhagens, apresentaram maior número de lesões neoplásicas. As médias de lesões (nódulos e hiperplasia) obtidas foram: CsU: 1,07( DP+ 1,54), CsSl: 0( DP+ 0), EsU: 2,57 ( DP+ 2,77) e EsS: 0,40 ( DP+ 1,12), com p < 0,001; CajNNK: 4,94( DP+ 3,54), CajS: 0,15( DP+ 0,37), EajNNK: 9,14 ( DP+ 7,70) e EajS:0,80 ( DP+ 1,93), com p<0,001. Não houve alterações para o p53 em ambas as linhagens e, apenas os grupos AJ controle e exposto NNK apresentaram diferença para o PCNA. CONCLUSÃO. A exposição crônica ao MP 2,5 proveniente da poluição atmosférica da cidade de São Paulo tem potencial para promover tumores em camundongos de duas linhagens diferentes, com ou sem o pré-tratamento por carcinógenos / INTRODUCTION. Epidemiological studies have shown that exposure to air pollution is associated with increased cardiorespiratory diseases. Previous experimental studies, we used urethane to induce lung nodule formation in mice and these animals exposed to pollution from \"real world.\" In these studies, animals were exposed to gases and particles in the same way that the population is exposed in the city of São Paulo. It was evident then, the role of promoter and dose dependent polluted atmosphere in the progression of lung tumors. It is known that carcinogens such as polycyclic aromatic hydrocarbons (PAHs), metals, aldehydes and fatty acids, are present in the respirable fraction particulate pollution (fine particulate matter - PM2.5), and prolonged exposure to the latter has been considered a risk factor for the development of lung cancer. The objective of this study is to verify whether chronic exposure to PM 2.5 concentration from the air of the city of São Paulo, has carcinogenic potential. METHODS. A total of 60 male Swiss mice (30 g) and 60 AJ (20g), with four to six weeks of life. The Swiss mice were pretreated with a carcinogen completed, the carbamic acid (urethane-U), while AJ received a carcinogen primer 4 - (methylnitrosamino) -1 - (3-pyridil)-1-butanone (NNK) as being predisposed to developing lung tumors. Then all the animals were exposed to atmospheric Harvard Particle Concentrator to PM 2.5 daily for two hours for four months. Each strain was divided into four groups (n = 15 each): 2 with saline controls and carcinogen (CsS and CsU or CajS and CajNNK) and 2 exposed to saline and carcinogen (EsS and EsS or EajS and EajNNK). After the exposure time, the animals were anesthetized and euthanized. The lungs were fixed, processed histologically and imunohistochemistry was performed on slides with tumor presence of antibodies to p53 and PCNA. Later, in histopathology of pulmonary nodules made counting and classification of lesions found. RESULTS. The animals exposed groups in both strains showed a high percentage of neoplastic lesions. Mean lesions (nodules and hyperplasia) were obtained: CsU: 1.07 (SD + 1.54), CsS: 0 (DP + 0), EsU: 2.57 (SD + 2.77) and EsS: 0.40 ( + SD 1.12), p < 0.001; CajNNK: 4.94 (SD + 3.54), CajS: 0.15 (SD + 0.37), EajNNK: 9.14 (SD + 7.70) and EajS: 0 , 80 (SD + 1.93), with p < 0.001. There were no changes to the p53 in both strains, and only groups A / J control and exposed to NNK differ PCNA. CONCLUSION. The chronic exposure to PM 2.5 air pollution from the city of São Paulo has the potential to promote tumors in mice of two different strains with or without pretreatment by carcinogens

<div>Mass spectrometry (MS) is a powerful and versatile analytical tool that is extensively used for the identification and analysis of complex mixtures. The ability to couple MS to atmospheric pressure ionization techniques and high-performance liquid chromatography (HPLC) or gas chromatography (GC) provides a high degree of experimental flexibility. MS is based on the analysis of gas-phase ions. Gas-phase ions are manipulated within the mass spectrometer and separated for detection based on their mass-to-charge (m/z) ratio.</div><div>One of the most commonly used techniques for complex mixture analysis is tandem mass spectrometry (MSⁿ). MSⁿ involves the isolation of the desired ion and allowing it to undergo reactions, such as collision-activated dissociation (CAD) or ion-molecule reactions. Based on the generated product ions, structural information can be obtained for unknown analytes in complex mixtures. In addition, MSⁿ methods based on diagnostic gas-phase ion-molecule reactions have been demonstrated to provide a general and predictable tool to identify specific functional groups in unknown ionized analytes and to classify unknown analytes into different compound classes depending on their functionalities.</div><div>The research described in this dissertation mainly focuses on the development of tandem mass spectrometric methods based on gas-phase ion-molecule reactions and/or CAD for the identification of the <i>N</i>-nitroso functionality, which is present in some potentially mutagenic drug impurities. Furthermore, the dissertation discusses combining machine learning and MSⁿexperiments based on diagnostic ion-molecule reactions of 2-methoxypropene to predict reaction outcomes in a semiautomated fashion for protonated analytes containing specific functional groups. Lastly, chemical characterization and gas-phase reactivity of the boron-centered radical dianion [B₁₂I₁₁]^2-• toward some organic molecules are discussed.</div>

No description available.

Na presente dissertação, o comportamento eletroquímico da nitrosamina aromática N-Nitrosodifenilamina (NDPhA) foi caracterizado em eletrodo de carbono vítreo (GCE) em meio aquoso através de técnicas eletroanalíticas e espectroscópicas. Para tal, propôs-se um mecanismo de oxidação em quatro etapas envolvendo quatro elétrons e quatro prótons, assim como de redução em três ou quatro etapas, dependendo do pH do meio, também envolvendo quatro elétrons e quatro prótons no total. Diferentes eletrodos de carbono (GCE e GPUE) foram comparados e caracterizados eletroquimicamente através de técnicas cronocoulométricas e voltamétricas, e microscopia de imagem (Microscopia Eletrônica de Varredura e Microscopia de Força Atômica) com objetivo de aplicá-los na quantificação de NDPhA em amostras de urina. Após otimização das condições experimentais, o GPUE demonstrou-se ser mais sensível que o GCE apresentando uma faixa linear de 2,5 a 17,5 &mu;mol L-1, com sensibilidade igual a 5,50 &mu;A L &mu;mol-1 cm-2, coeficiente de correlação igual a 0,9998 e limite de detecção igual a 0,27 /&mu;mol L-1, apresentando sensibilidade cinco vezes maior e limite de detecção calculado cerca de 20 vezes menor. O preparo do eletrodo e a resposta do mesmo se mostraram reprodutível ao longo do tempo. Ademais, o método desenvolvido foi aplicado em uma amostra de urina sintética, utilizando o método de adição e recuperação, e foi possível concluir que esse processo pode ser aplicado a essa amostra com 95% de confiança. / In the present dissertation, the electrochemical behaviour of the aromatic nitrosamine N-Nitrosodiphenylamine (NDPhA) on the Glassy Carbon Electrode (GCE) in aqueous medium was characterized through electroanalytical and spectroscopic techniques. A four-step oxidation mechanism was proposed involving four electrons and four protons, as well as a reduction in three or four steps, depending on the pH of the medium, also involving four electrons and four protons in total. Different carbon electrodes (GCE and GPUE) were compared and characterized electrochemically by chronocoulometry and voltammetric techniques, and image microscopy (Scanning Electron Microscopy and Atomic Force Microscopy) with the objective of applying them to the quantification of NDPhA in urine samples. After optimization of the experimental conditions, the GPUE presented to be more sensitive than the CGE with a linear range of 2.5 to 17.5 &mu;mol L-1, with sensitivity equal to <br /> 5.50 &mu;A L &mu;mol-1 cm-2, correlation coefficient equal to 0.9998 and detection limit equal to 0.27 / &mu;mol L-1, with sensitivity five times higher and detection limit calculated about 20 times lower. The preparation of the electrode and its response proved to be reproducible over time. In addition, the developed method was applied in a synthetic urine sample, using the addition and recovery method, and it was possible to conclude that this process can be applied to this sample with 95% confidence.

No description available.

La spécialisation des techniques agricoles que nous connaissons ces dernières décennies, particulièrement dans les régions rurales, est à l’origine de l’abus de fertilisants. Ces derniers sont actuellement reconnus comme étant les causes principales de la contamination de l’eau souterraine par les nitrates. Suite à leur ingestion via l’eau potable, les nitrates sont transformés en nitrites par la flore buccale. Une fois dans l’estomac les nitrites réagissent avec certaines amines provenant de l’alimentation pour générer des nitrosamines cancérogènes. L’objectif de notre étude était d’estimer quantitativement l’excès de risque de cancer (ER) pour les populations de sept régions rurales du Québec qui consomme l’eau potable provenant de réseaux municipaux alimentés en eau souterraine. Le territoire à l’étude était caractérisé par une agriculture intensive d’élevage. Les médianes (et 95e centiles) régionales des concentrations de nitrates mesurées dans les réseaux de ces régions étaient de : 0,18 (2,74); 0,48 (10,35); 0,15 (1,28); 0,32 (11); 0,05 (0,76); 0,10 (4,69); 0,09 (2,13) mg N-NO3-/l. Nous avons envisagé un scénario de transformation complète des nitrites et de certaines amines (diméthylamine, diéthylamine, n-butylamine, méthyléthylamine) en nitrosamines spécifiques : N-diméthylnitrosamine (NDMA), N-diéthylnitrosamine (NDEA), N-n-dibutylnitrosamine (NDBA) et N-méthyléthylnitrosamine (NMEA). Pour estimer la concentration de nitrites formés dans l’estomac, nous avons considéré une consommation définie d’eau potable, le volume de l’estomac et un taux de transformation des nitrates en nitrites. Supposant les quantités de nitrites et de chaque amine constantes pendant 1h, nous avons considéré la constante de nitrosation spécifique à chaque amine pour évaluer la dose d’exposition journalière à chaque nitrosamine équivalente formée. Par la suite, la combinaison de cette dose à un estimateur de potentiel cancérogène qhumain spécifique à chaque nitrosamine, nous a permis d’évaluer l’ER associé à chacune d’elles. Globalement l’analyse a démontré que les ER les plus élevés, estimés pour le NDBA, étaient de l’ordre de 10-6, ne contribuant pas de façon significative à une augmentation du risque de cancer pour ces populations. / Specialization of agricultural practices in rural regions over the past few decades has led to overuse of fertilizers which are main causes of groundwater contamination by nitrates. After their ingestion through drinking water, nitrates are transformed into nitrites by the oral flora. Once in the stomach, nitrites react with some amines from food supply to form nitrosamines with some being probably carcinogenic to humans. The aim of this study was to quantitatively estimate the possible excess cancer risk (ER) for populations of seven rural regions in Quebec that consume water from public drinking water systems using groundwater. The studied regions practice extensive breeding agriculture. The regional medians (and 95th percentile) of nitrate levels in water from those seven regions were: 0.18 (2.74); 0.48 (10.35); 0.15 (1.28); 0.32 (11); 0.05 (0.76); 0.10 (4.69) and 0.09 (2.13) mg N-NO3-/l, respectively. Indeed, we first considered a scenario of complete transformation of nitrites and some amines (dimethylamine, diethylamine, n-butylamine and methylethylamine) into specific nitrosamines: N-dimethylnitrosamine (NDMA), N-diethylnitrosamine (NDEA), N-nitrosodi-n-butylamine (NDBA) and N-nitrosomethylethylamine (NMEA). Gastric nitrite concentrations were estimated on the basis of defined drinking water intake, stomach volume, and the transformation rate of nitrates into nitrites. Considering that levels of nitrites and each amine were kept constant for 1 hour, and taking in account the nitrosatability rate constant specific to each amine, we then estimated the daily doses of the corresponding endogenously formed nitrosamines. Furthermore combination of dose with the human cancer potency factor qhuman specific to each nitrosamine, allowed the estimation of excess cancer risk. The highest ER estimated for NDBA was in the order of 10-6, thus not contributing to a significant increase in the risk of cancer for that population.

La fumée de tabac contient plusieurs substances carcinogènes qui mènent à la formation constante de petites quantités de dommages à l'ADN dans les poumons des fumeurs ainsi que des non-fumeurs exposés à la fumée environnementale de tabac. La 4-(méthylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) est l'une de ces substances et elle semble plus particulièrement associée avec le développement des adénocarcinomes, la forme de cancer pulmonaire dont l'incidence progresse le plus rapidement ces dernières années. Dans les cellules pulmonaires, la NNK est bioactivée via des cytochromes P450 en intermédiaires réactifs capables de méthyler ou de pyridyloxobutyler l'ADN. Les dommages résultant de ces deux modes d'activation de la NNK peuvent être investigués séparément en utilisant des analogues qui génèrent sélectivement l'un ou l'autre type d'intermédiaires réactifs. Le test des comètes est une technique simple, très sensible et couramment utilisée pour étudier au niveau cellulaire les dommages à l'ADN qui sont peu fréquents. Les travaux présentés dans cette thèse montrent que certains des dommages résultant de l'activation de la NNK peuvent être investigués de manière spécifique à l'aide de cette technique, et ce à des fréquences de dommages qui se rapprochent de celles correspondant à une exposition réelle à la fumée de tabac. Parmi ces dommages, un type d'adduits encore inconnu associé à la pyridyloxobutylation de l'ADN a pu être mis indirectement en évidence. Il s'agit vraisemblablement de la forme formamidopyrimidine (fapy) d'une lésion primaire formée dans les cellules. La vitesse de réparation d'un type de dommage influe sur le risque qu'il a d'être impliqué dans la transformation maligne des cellules. La disparition des dommages dans le temps a pu être suivie avec le test des comètes afin d'investiguer la réparation dans des cellules capables ou pas de bioactiver la NNK. Le suivi post-traitement des dérivés fapy associés à la pyridyloxobutylation de l'ADN, a montré un phénotype ne dépendant pas du type cellulaire mais plutôt du statut de p53 dans les cellules. En effet, au lieu de diminuer après la fin du traitement, la fréquence des adduits fapy dans les fibroblastes augmente dans un premier temps et ce, seulement dans les cellules ayant une protéine p53 fonctionnelle. La nature de ce phénotype particulier n'est pas clairement identifiée, mais elle est vraisemblablement liée à la réparation des dommages à l'ADN. / Tobacco smoke contains several carcinogens that lead to the frequent formation of rare DNA damage in lungs of smokers. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is one of these substances that seems more particularly associated with the development of adenocarcinoma. During the last 30 years, the frequency of this lung cancer type has increased significantly. In lung cells, cytochromes P450 can bioactivate NNK into reactive species capable of either methylating or pyridyloxobutylating DNA. The use of analogs capable of generating only one type of NNK-associated reactive species allows to investigate methylation and pyridyloxobutylation separately. The comet assay is a simple and sensitive technique that is commonly used to investigate low frequency DNA damage at the cellular level. The work presented here show how some of the NNK-related DNA damage can be investigated specifically with this technique at damage frequencies that are relevant to a real exposure to cigarette smoke. One of the adduct type resulting of DNA pyridyloxobutylation that we studied here had never been demonstrated before. It corresponds likely to the formamidopyrimidine (fapy) form of a lesion primarily formed in cells. The repair rate of a damage type influences the probability that it has to be implicated in mutagenesis. The time course of different damage types was documented with the comet assay in order to investigate the repair of NNK-related damage in different cell types that can either bioactivate NNK or not. When the fapy adducts associated with pyridyloxobutylation were investigated post-treatment, their time course did not depend on the cell type but showed a p53-dependant phenotype. In fact, instead of decreasing because of repair, the frequency of these fapy adducts in fibroblasts first increased post-treatment and this increase seemed associated with p53 proficiency. The cause of this phenotype is not clearly elucidated but it should be related to DNA damage repair.