Dans ce travail, l'oxydation totale du toluène et de la butanone sur des catalyseurs à base d'or et de palladium supportés sur un oxyde de titane macro-mésoporeux a été étudiée. Nous avons tout d'abord discuté l'effet bénéfique du dopage (V, Nb, Fe, Ce, Ni) du support TiO₂ macro-mésoporeux sur l'activité catalytique de ce matériau. Une interaction existant entre le dopant et le support a joué un rôle important dans l'augmentation de l'activité des matériaux dopés par rapport à celle du titane pure. Une phase active constituée d'or et/ou de palladium a été ensuite déposée sur les solides dopés et la performance des catalyseurs préparés a été suivie dans l'oxydation du toluène et de la butanone. La présence de la phase active a assuré une sélectivité totale pour le CO₂ avec la formation de sous-produits en particulier dans l'oxydation de la butanone. Par ailleurs, l'oxydation du mélange des deux COVs a montré l'existence d'une compétition entre les molécules en terme d'adsorption sur le support, ce qui a favorisé leur éliminationà de basses températures. Une étude operando DRIFT réalisée dans l'oxydation du mélange toluène/butanone a vérifié la présence de cette compétition. / In this work, the total oxidation of toluene and butanone over noble metal loaded doped titanium oxide supports has been investigated. The study focused firstly on showing the effect of doping a macro-mesoporous titania with metal oxide supports in the oxidation of VOCs. It seems that doping enhances the performance of the used solid in VOC oxidation reactions. We proved that this increase can be directly related to interactions between the dopants and the support. Then, an active phase made of noble metals has been loaded onto both best performing doped materials as to study the role played by this active phase in oxidation reactions. It appears that the presence of noble metals increases the catalytic performance of prepared materials and reduces the formation of toxic by-products such as CO. Butanone elimination proved to be harder that toluene oxidation, whereas when catalysts were exposed to a mixture of toluene and butanone, the presence of both VOCs prompted a competitive effect in the adsorption of both molecules onto the support, which facilitated their oxidation rate. An FTIR operando study illustrated the changes occuring in used catalysts in the oxidation of the VOC mixture, and verified the existence of this competitive effect.

Tobacco-specific nitrosamines (TSNA) are carcinogenic constituents derived from alkaloids in tobacco. Researchers are actively exploring several avenues to reduce TSNA levels in tobacco products like moist snuff tobacco. The focus of the research presented within is the quantitative analysis of TSNA in tobacco, specifically N’-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1(3-pyridyl)-1-butanone (NNK), N’-nitrosoanatabine (NAT), and N’-nitrosoanabasine (NAB). Tobacco alkaloids and nitrosamines in tobacco are currently analyzed by different instrumentation due to orders of magnitude difference in their concentrations, chromatographic separation challenges due to structural similarities, and similar mass fragmentation patterns. An analytical column using silica and 1,2-bis(siloxy)ethane hybrid particles of 1.7 µm size is the foundation of a chromatographic separation of NNN, NNK, NAT, NAB, nicotine, nornicotine, anatabine, and anabasine. This is the first rapid and robust quantitative method for the TSNA and their alkaloid precursors using high pH mobile phase conditions with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The suitability of the method is demonstrated by its application to the analysis of reference tobacco materials for cigarettes and moist snuff. In addition, a novel TSNA analytical method was developed using TSNA-specific molecularly imprinted polymers (MIP) as the selective extraction element from tobacco extract. The affinity mechanisms between MIP and TSNA were found to have extensive cross-reactivity to structurally similar alkaloids present in tobacco extract. TSNA-specific MIP was demonstrated to have stronger retention for the alkaloids than for the TSNA substrate. The MIP-TSNA interaction was optimized to create the first analytical method to quantify underivatized NNN and NNK from tobacco extracts by HPLC-UV.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent pulmonary carcinogen found in unburned tobacco and tobacco smoke. To exert its carcinogenic effect, NNK is metabolically activated to reactive intermediates that can damage DNA by alkylation or pyridyloxobutylation. NNK also has the ability to induce DNA oxidation and alter DNA repair activities that can result in deficient repair and potentially exacerbate carcinogenesis. Base excision repair (BER) is a ubiquitous DNA repair system that mainly repairs oxidative DNA damage. The goal of this study was to determine the effect of NNK on DNA oxidation status and BER activity in A/J mouse lung and liver. Female mice were treated with 10 µmol of NNK i.p. and lung and liver were isolated 1, 2 and 24 hours post administration. DNA was isolated from lung and liver, and the formation of 8-hydroxydeoxyguanosine (8-OHdG, a biomarker of DNA oxidation) was assessed by high-performance liquid chromatography with electrochemical detection. At 1, 2 and 24 hours in both murine lung and liver, there was no statistically significant difference in 8-OHdG levels (n = 4, P > 0.05) between control and NNK-treated mice. To assess BER, cell-free whole tissue nuclear protein extracts from liver and lung were prepared and incubated with a plasmid substrate containing oxidative DNA damage. In vivo treatment with NNK did not alter BER activity in lung or liver compared to control mice (n=3 or 4, P > 0.05). These experiments indicate that acute treatment with a tumourigenic dose of NNK does not significantly stimulate oxidative DNA damage or significantly alter BER activity in murine lung and liver. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2011-04-28 17:42:08.172

Thèse (Ph.D)--Université Laval, 2001. / Titre de l'écran-titre (visionné le 22 mars 2004). Bibliogr. Présenté aussi en version papier.

Thèse (M.Sc.) -- Université Laval, 1997. / Bibliogr.: f. 74-84. Publ. aussi en version électronique.

Alveolar macrophages (AM) play an important role in pulmonary homeostasis by their cellular functions which include inflammatory mediator production and cytotoxic activity. Epithelial cells are known for their role as a physical barrier, gas exchange and ion and fluid transport. However, they can also initiate the pulmonary immune response by secreting many inflammatory mediators. The functions of these two cell types are affected by cigarette smoke, which is composed of more than 4 000 compounds, 20 of which are known to be pulmonary carcinogens. One of these carcinogens, 4-(methylnitrosamino)-l- (3-pyridyl)-l-butanone (NNK), has a strong specificity for pulmonary tissues. This compound also has an immunomodulatory effect on AM mediator production. Many metabolic pathways of NNK performed by AM may be responsible for the immunomodulatory effects observed. We investigated these pathways to characterize the major one implicated in the effects of NNK on AM. We also studied the implication of NNK on cytotoxic activity of AM against tumoral cells. Knowing the importance of epithelial cells in the pulmonary immune response, we investigated the effect of NNK on these cells at the bronchial and alveolar level and identified the major pathway implicated. Our study showed that the a-methylhydroxylation pathway is responsible for the immunomodulatory effects on AM and epithelial cells. NNK, like cigarette smoke, inhibits AM cytotoxicity. This study indicates that NNK modulates cellular function of both AM and epithelial cells. Cell-cell communication between these two cell types being a leading event in the pulmonary immune response, we investigated the effect of NNK on this communication. This study, specific to NNK's modulatory effect on immune response, shows the global effect of NNK at the pulmonary level. This study also reports that NNK carcinogenic mechanism may involved the inhibition of defence pulmonary mechanisms in addition to forming DNA adducts. / Plusieurs cellules pulmonaires, dont les macrophages alvéolaires (MA) et les cellules épithéliales, peuvent être affectées par une exposition à la fumée de cigarette. Les MA sont responsables de l'intégrité immunologique du poumon de par leurs nombreuses fonctions dont la production de médiateurs inflammatoires et leur activité cytotoxique. Les cellules épithéliales sont reconnues pour leur rôle de barrière physique, les échanges gazeux ainsi que le transport ionique et liquidien, mais elles peuvent aussi initier la réponse immune pulmonaire en sécrétant différents médiateurs inflammatoires. La fumée de cigarette contient plus de 4000 composants, dont une vingtaine sont des cancérigènes pulmonaires, dont la 4-(methylnitrosamino)-l-(3-pyridyl)-l-butanone (NNK). Plusieurs voies d'activation métabolique de la NNK sont présentes chez les MA et peuvent expliquer l'effet immunomodulatoire de ce cancérigène sur ces cellules. Nous avons caractérisé la voie d'activation métabolique majeure de la NNK impliquée dans la modulation de ce composé chez les MA en plus d'étudier son effet sur l'activité cytotoxique des MA envers les cellules tumorales. En plus de déterminer la voie principale d'activation métabolique de la NNK chez les cellules épithéliales, nous avons aussi investi gué l'effet de la NNK sur la production de médiateurs inflammatoires par les cellules épithéliales bronchiques et alvéolaires,. Cette étude démontre que la voie d'a-méthylhydroxylation de la NNK est responsable de l'effet immunomodulateur de celle-ci sur les MA et sur les cellules épithéliales. La NNK, comme la fumée de cigarette, inhibe l'activité cytotoxique des MA. Cette inhibition pourrait contribuer à la survie et à la prolifération des cellules tumorales. La communication cellule-cellule entre les MA et les cellules épithéliales joue un grand rôle dans l'initiation de la réponse immune pulmonaire. Pour démontrer l'effet de synergie de cette communication sur la production de cytokines dans les co-cultures, nous avons exposé des co-cultures de MA et de cellules épithéliales alvéolaires à la NNK. Cette étude, spécifique au pouvoir immunomodulatoire de la NNK sur la réponse immune, précise davantage l'effet global que ce composé peut avoir au niveau pulmonaire. Cette étude indique que la NNK pourrait contribuer au développement des cellules tumorales en inhibant les défenses cellulaires de l'organisme face à ces cellules en plus d'induire la formation d'adduits d'ADN et l'inhibition de la réparation de l'ADN.

Dans le cadre du projet DISPATMO (étude de la prévision des risques de pollution liés à la dispersion atmosphérique de produits chimiques), des études de risques liés aux incendies et explosions dus aux produits chimiques stockés sur deux sites tests ont été menées. Le but est d’identifier les produits de combustion de certains composés cibles définis au début du projet, ainsi que d’estimer leur concentration. Les composés tests sont l’éthanol, le 2-butanone, le toluène et le solvant TIFLEX. Ces composés sont susceptibles, surtout à richesse élevées, de former des quantités non-négligeables d’isomères du butène, composés chimiques connus pour être d’importants intermédiaires de la combustion d’hydrocarbures. Après une étude bibliographique sur les isomères du butène, de l’éthanol, de la 2-butanone et du toluène, un mécanisme cinétique détaillé pour simuler l’oxydation de ces composés a été proposé. Une étude expérimentale de l’oxydation de 4 butènes (1-butène, trans-2-butène, cis-2-butène et iso-butène) a été réalisée en réacteur auto-agité (T = 900-1440 K, p = 1 atm, = 0,25, 0,5, 1 et 2, = 70 ms) et en chambre de combustion sphérique (Ti = 300 K, pi = 1, 2, 3 et 5 atm, = 0,8-1,4). Les résultats obtenus ont été confrontés à la simulation. Des données expérimentales issues de la littérature ont été utilisées afin de valider le modèle pour l’oxydation de l’éthanol, de la 2-butanone, du toluène et des isomères du butène. Enfin, une étude expérimentale de l’oxydation du solvant TIFLEX a été menée en réacteur auto-agité (T = 740-1310 K, p = 1 atm, = 0,5, 1 et 2) pour en connaître la composition ainsi que pour identifier et quantifier les produits d’oxydation. Le mécanisme cinétique proposé comporte un coeur C0-C4 robuste, en faisant un outil prédictif fiable, pouvant servir de base à des mécanismes plus étendus capables de représenter la combustion de nombreuses autres espèces (alcanes, alcènes, alcools, aldéhydes ou cétones), par ajout de sous-mécanismes. / In the context of the DISPATMO project (study of the forecast of the risks of pollution related to the atmospheric dispersal of chemicals), risk studies linked to the fires and the explosions due to chemical storage were conducted. The purpose is to identify the combustion products of certain target compounds defined at the beginning of the project, as well as to estimate their concentration. The target compounds include ethanol, 2-butanone, toluene and the solvent TIFLEX. These compounds lead, especially in fuel-rich conditions, to the formation of high quantities of butene isomers, compounds known as important intermediates of hydrocarbon combustion. After a bibliographical study on butene isomers, ethanol, 2- butanone and toluene, a detailed kinetic mechanism for the simulation of the oxidation of these compounds was proposed. An experimental study of the oxidation of the butene isomers was performed in a jet-stirred reactor (T = 900-1440 K, p = 1 atm, = 0.25, 0.5, 1 and 2, = 70 ms) and in a spherical combustion chamber (Ti = 300 K, pi = 1, 2, 3 and 5 atm, = 0.8-1.4). Experimental results were compared with their simulations. Experimental data from the literature were used to validate the model for the oxidation of ethanol, 2-butanone, toluene and butene isomers. Finally, an experimental study of the oxidation of the solvent TIFLEX was performed in the jet-stirred reactor (T = 740-1310 K, p = 1 atm, = 0.5, 1 and 2) in order to know the composition as well as to identify and quantify of the oxidation products. The proposed kinetic mechanism contains a strong C0-C4 base, resulting in a reliable predictive tool, which can be used as a base in larger mechanisms simulating the combustion other species (alkanes, alkenes, alcohols, aldehydes or ketones), by addition of sub-mechanisms.

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is believed to play a role in human lung cancer induced by tobacco smoking. NNK biotransformation may involve the enzymes prostaglandin H synthase (PHS)-1, PHS-2 and cytochrome 450 (CYP) 2F. PHS activity is thought to be important in extrahepatic tissues, where CYP activity is low. The CYP2F subfamily contains a single functional enzyme in humans (CYP2F1) and goats (CYP2F3); these enzymes are preferentially expressed in the lung, with little or no expression in other organs. The role of these enzymes in the pulmonary biotransformation of NNK was investigated. 4.2 µM [5-3H]NNK was incubated with human lung microsomes under NADPH-dependent and arachidonic acid-dependent conditions. Metabolites reflective of NNK α-carbon hydroxylation, N-oxidation and carbonyl reduction were detected in the presence of NADPH, and metabolite levels for all three biotransformation pathways were lower in the presence of arachidonic acid compared with NADPH (p<0.05, N=4). Incubation of microsomes with the PHS-1 selective inhibitor SC-560 and the PHS-2 selective inhibitor NS-398 did not change NNK biotransformation either in the presence of NADPH or in the presence of arachidonic acid (p>0.05, N=4). Incubation of [5-3H]NNK with ovine PHS-1 or PHS-2 did not result in formation of α-carbon hydroxylation or N­-oxidation metabolites; 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was measurable only in the presence of PHS-2. Incubation of goat recombinant CYP2F3 with [5-3H]NNK resulted in formation of keto acid, keto alcohol and NNK-N-oxide (65.0%, 17.5% and 30.0% (µmol enzyme)-1 minute-1, respectively). Metabolite formation was inhibited by 3-methylindole (3-MI), a mechanism-based inactivator of CYP2F3. Based on an N value of 3, incubation of human lung microsomes with 3-MI inhibited N-oxidation (p<0.05) but did not alter NNK bioactivation or carbonyl reduction (p>0.05). However, when metabolite formation was examined in lung microsomes from different individuals, decreases in NNK biotransformation (ranging from 19.6 to 68.5%) were observed and were more pronounced in some patients than others, suggesting inter-individual variability in CYP2F1 activity. These studies demonstrate the ability of CYP2F to biotransform NNK and suggest inter-individual variability in the importance of CYP2F1 for this activity in human lung. They also strongly argue against the involvement of PHS enzymes. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2007-12-30 16:12:58.228

Studies described in this thesis were at aimed at characterizing the mechanisms involved in the pulmonary carcinogenicity of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), by addressing two critical determinants of carcinogenicity; biotransformation and DNA repair. The contributions of cytochrome P450 (CYP) 2A13 and CYP2A6 to NNK biotransformation in human lung microsomes were investigated. Based on total bioactivation and detoxification of NNK and its keto-reduced metabolite, 4 (methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), subjects could be classified as either high or low bioactivators and detoxifiers. Data from all of 29 individuals revealed no correlations between levels of CYP2A mRNA, enzyme activity or immunoinhibition and the degree of total NNK bioactivation or detoxification. However, subgroups were identified for whom CYP2A13 mRNA correlated with total NNK and NNAL bioactivation (n=4) and NNAL detoxification (n=5). Although results do not support CYP2A13 or CYP2A6 as predominant contributors to NNK metabolism in lung of all individuals, CYP2A13 appears to be important in some. The involvement of nucleotide excision repair (NER) in the repair of NNK-induced DNA pyridyloxobutylation was assessed. Extracts from NER-deficient cells were less active at repairing pyridyloxobutyl (POB) adducts on plasmid DNA than were extracts from normal cells, and NER-deficient cells were more susceptible to 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc)-induced cytotoxicity, demonstrating the participation of NER in the repair of POB-DNA adducts. The role of DNA repair in contributing to inter-organ susceptibility to NNK-induced carcinogenesis was investigated. POB adduct repair was greater in extracts from mouse liver than lung, and activities in lungs of NNK-treated mice were lower than those of saline-treated mice, while repair was 3 times higher in livers of NNK-treated mice relative to control. NNK treatment decreased incision of POB adducts by 92 % in lung extracts and increased incision by 169 % in liver extracts. In addition, NNK altered the levels and binding to POB damage of key incision proteins. These results suggest that lower NER incision activity and NNK-mediated alterations in levels and activities of incision proteins contribute to the relative susceptibility of mouse lung to NNK-induced carcinogenesis. / Thesis (Ph.D, Pharmacology & Toxicology) -- Queen's University, 2008-11-13 14:10:01.603

Dans ce travail, l'oxydation totale du toluène et de la butanone sur des catalyseurs à base d'or et de palladium supportés sur un oxyde de titane macro-mésoporeux a été étudiée. Nous avons tout d'abord discuté l'effet bénéfique du dopage (V, Nb, Fe, Ce, Ni) du support TiO₂ macro-mésoporeux sur l'activité catalytique de ce matériau. Une interaction existant entre le dopant et le support a joué un rôle important dans l'augmentation de l'activité des matériaux dopés par rapport à celle du titane pure. Une phase active constituée d'or et/ou de palladium a été ensuite déposée sur les solides dopés et la performance des catalyseurs préparés a été suivie dans l'oxydation du toluène et de la butanone. La présence de la phase active a assuré une sélectivité totale pour le CO₂ avec la formation de sous-produits en particulier dans l'oxydation de la butanone. Par ailleurs, l'oxydation du mélange des deux COVs a montré l'existence d'une compétition entre les molécules en terme d'adsorption sur le support, ce qui a favorisé leur éliminationà de basses températures. Une étude operando DRIFT réalisée dans l'oxydation du mélange toluène/butanone a vérifié la présence de cette compétition.