A avaliação do risco é um processo sistemático pelo qual a possibilidade de dano, a exposição e o próprio risco são identificados e quantificados. A consideração, de que a participação em um estudo é de risco, fundamenta-se no princípio da precaução, que é a garantia da existência de medidas de proteção contra riscos potenciais. De acordo com a gravidade dos eventos adversos, e de sua probabilidade de ocorrência, determina-se se o risco previsto é negligenciável, tolerável ou intolerável. Portanto, a caracterização do risco representa um importante elo entre os dados científicos obtidos nos diferentes estudos e as tomadas de decisões, ao monitoramento e à comunicação do risco. O objetivo deste estudo é avaliar os riscos previstos de eventos adversos gastrintestinais em projetos de pesquisa em seres humanos na área farmacológica, realizados no Hospital de Clínicas de Porto Alegre (HCPA), através da análise do Termo de Consentimento Livre e Esclarecido (TCLE), do manual do pesquisador e do projeto. Realizou-se um estudo transversal, com unidade de observação nos eventos adversos (EAs) gastrintestinais, através do levantamento de risco de projetos de pesquisa farmacológica, com patrocínio privado, submetidos e aprovados pelo Comitê de Ética em Pesquisa (CEP) do HCPA, no ano de 2004. De 58 projetos analisados, identificou-se 9734 referências de riscos de EAs gerais, sendo que 1463 (15,0%) eram gastrintestinais. Destas, 181 (12,4%) aparecem somente no TCLE, desprovida de embasamento teórico; já 1047 (71,6%) estão descritas nos documentos não disponibilizados ao participante, informação não compartilhada, tendo embasamento teórico; e apenas 235 referências de riscos, que representam 16,0% dos riscos gastrintestinais totais, como informação compartilhada e documentada, para o participante e pesquisador, com embasamento teórico. Essas 1463 referências de riscos de EAs gastrintestinais foram padronizadas, fazendo-se uso do Código Internacional de Doenças, décima revisão (CID 10), obtendo-se 170 tipos diferentes de riscos. Os riscos com maior repetição de referência nos projetos foram: náusea e vômitos 14,1%; alteração do hábito intestinal 6,5%; aumento dos níveis de transaminases e da desidrogenase lática 5,7%; outras dores abdominais e as não especificadas 4,9%. Quanto à gravidade, dos 170 tipos de riscos, obteve-se 65 (38,2%) graves, 52 (30,6%) moderados, 30 (17,6%) leves e 23 (13,5%) múltipla classificação. Todos os documentos relativos ao projeto de pesquisa deveriam conter a descrição e quantificação dos riscos importantes, seja pela alta gravidade ou freqüência associada. No TCLE, parte dos riscos estavam descritos, porém desprovidos de uma quantificação e caracterização adequadas. O manual apresentava as informações sobre os riscos, mas de forma dispersa ao longo do documento, levando a uma dificuldade de utilização desses dados nas intervenções propostas. Nos projetos analisados, observa-se a falta de homogeneidade e padronização para se expressar adequadamente os riscos já ocorridos em estudos prévios. Isso demonstra a importância da leitura atenta de toda documentação encaminhada para avaliação pelo CEP, visando a proteção ativa dos sujeitos da pesquisa. / Risk evaluation is a systematic process whereby damage possibility, exposure and the risk itself are identified and quantified. The consideration that the participation in a study is risky is founded on the precaution principle, i.e., the warranty of existing protection measures against potential risks. According to the severity of the adverse events and of its occurrence probability, one determines if the foreseen risk is negligible, tolerable or intolerable. Therefore, risk characterization represents an important link between the scientific data obtained from the different studies and the decision-makings, to monitoring and to risk communication. The objective of this study is evaluating the foreseen risks of gastrointestinal adverse events (AEs) in research projects with human beings in the pharmacological field carried out at Hospital de Clínicas de Porto Alegre – HCPA by means of the Informed Consent Form – ICF, of the researcher brochure and of the Research Protocol. A transversal study was carried out with an observation unit in the gastrointestinal AEs, through the survey of risk of projects of clinical trial with private sponsorship submitted to and approved by the Research Ethics Committee – REC of the HCPA in 2004. Out of 58 analyzed protocols were identified 9734 risk references of general AEs, being 1463 (15.0%) gastrointestinal. Out of these, 181 (12.4%) appear on the ICF only, deprived of theoretical basis; while 1047 (71.6%) are described in documents non available for the participant, non-shared information, with theoretical basis; only 235 risk references that represent 16.0% of the total gastrointestinal risk, as shared and documented information for the participant and the researcher, having theoretical basis. These 1463 risk references of gastrointestinal AEs were standardized by making use of the International Code of Diseases – 10th Revision –, and 170 different risk types were obtained. The risks with more reference repetition in the protocols were: nausea and vomit 14.1%; alteration of intestinal habit 6.5%; increase of the levels of transaminases and of lactic dehydrogenase 5.7%; abdominal pain 4.9%. As to the severity, out of the 170 risk types, 65 (38.2%) are severe, 52 (30.6%) moderate, 30 (17.6%) soft and 23 (13.5%) of multiple classification. All of the documents regarding the research protocol should contain the description and quantification of the important risks either due to high severity or to frequency. In the ICF, some of the risks were described however deprived of an adequate quantification and characterization. The brochure presented the information about the risks, however in a disperse way over the document leading to a difficult utilization of these data in the proposed interventions. In the analyzed protocols was observed lack of homogeneity and standardization to adequately express the risks that had already occured in previous studies. This observation demonstrates the importance of careful reading of all of the documentation addressed for evaluation by the REC aiming at the active protection of the research subjects.

CTRP3 is a secreted plasma protein of the C1q family that helps regulate hepatic gluconeogenesis and is downregulated in a diet-induced obese state. However, the role of CTRP3 in regulating lipid metabolism has not been established. Here, we used a transgenic mouse model to address the potential function of CTRP3 in ameliorating high-fat diet-induced metabolic stress. Both transgenic and wild-type mice fed a high-fat diet showed similar body weight gain, food intake, and energy expenditure. Despite similar adiposity to wild-type mice upon diet-induced obesity (DIO), CTRP3 transgenic mice were strikingly resistant to the development of hepatic steatosis, had reduced serum TNF-α levels, and demonstrated a modest improvement in systemic insulin sensitivity. Additionally, reduced hepatic triglyceride levels were due to decreased expression of enzymes (GPAT, AGPAT, and DGAT) involved in triglyceride synthesis. Importantly, short-term daily administration of recombinant CTRP3 to DIO mice for 5 days was sufficient to improve the fatty liver phenotype, evident as reduced hepatic triglyceride content and expression of triglyceride synthesis genes. Consistent with a direct effect on liver cells, recombinant CTRP3 treatment reduced fatty acid synthesis and neutral lipid accumulation in cultured rat H4IIE hepatocytes. Together, these results establish a novel role for CTRP3 hormone in regulating hepatic lipid metabolism and highlight its protective function and therapeutic potential in attenuating hepatic steatosis.

This thesis describes studies in patients with inflammatory bowel disease (IBD) and collagenous colitis (CC). We investigated mucosal eosinophil and neutrophil granulocytes and T-cells involved in the inflammatory processes and aimed at determining whether these processes are reflected in the faecal (F) contents of specific proteins secreted by cells in the intestinal mucosa. Thus, we measured eosinophil cationic protein (ECP) and eosinophil protein X (EPX) and the neutrophil derived myeloperoxidase (MPO) and calprotectin (C); and in addition, chromogranin A (CgA), Chromogranin B (CgB) and secretoneurin (SN), derived from EEC cells and cells in the enteric nervous system. We found that a normalised FC level can serve as a surrogate marker for successful treatment in patients with IBD, but persistently high FC levels need further evaluation (study I). Furthermore, FC and F-MPO appear to relate better than F-EPX to treatment outcome in IBD. We evaluated F-ECP, F-EPX, F-MPO and FC as markers of disease activity and treatment outcome in patients with CC (study III) and concluded that F-ECP was the best discriminator of detecting active CC. Normalised F-ECP and F-EPX could serve as markers of successful treatment. We showed that the inflammation in CC is characterised by activated eosinophils, but that there is no neutrophil activity (study II). T-cells have a lower grade of activity in active CC than in control subjects. During budesonide treatment the normal activation of eosinophils and T-cells is restored, with concomitant clinical remission. The findings in studies II and III indicate that the eosinophils have an essential role in the pathophysiology of CC. Markedly higher values of F-CgA, F-CgB and F-SN were found in patients with CC than in those with IBD and controls (study IV) indicating a crucial role for the intestinal neuro-endocrine system in the pathogenesis of collagenous colitis.

La consommation excessive d'alcool est la première cause de cirrhose en France. L'atteinte hépatique débute par une stéatose (accumulation de triglycérides dans les hépatocytes) qui peut évoluer vers un état inflammatoire (hépatite alcoolique) lors d'une consommation chronique d'alcool. La maladie peut ensuite évoluer vers la fibrose, la cirrhose et jusqu'à l'hépatocarcinome. La mortalité des formes aiguës de l'hépatite alcoolique sévère est comprise entre 50 et 75%. La corticothérapie est le seul traitement qui peut améliorer le pronostic à court terme. D'autres facteurs que la seule consommation excessive d'alcool interviennent dans la genèse des lésions hépatiques. Ainsi, parmi les sujets ayant une forte consommation d'alcool à long terme, la majorité des patients développent une stéatose mais seulement 10 à 35% développeront une hépatite et 8 à 20% évolueront vers la cirrhose. La recherche de facteurs qui relient la consommation d'alcool et la nature et progression des lésions hépatiques est donc essentielle pour trouver de nouvelles cibles thérapeutiques améliorant la prise en charge de ces formes graves. Afin de rechercher quels sont ces facteurs, nous avons utilisé un modèle murin d'alcoolisation. Nous avons utilisé un régime Lieber de Carli (LDC) enrichi en graisses, additionné d'alcool ou non. Nous avons orienté notre projet vers un axe microbiote-inflammation hépatique en analysant l'évolution des populations bactériennes intestinales au cours de la surconsommation d'alcool chez la souris. Des résultats nous ont montré que les Bacteroides variaient grandement d'une animalerie à l'autre. L'objet de nos travaux était d'étudier l'effet de la modulation des Bacteroides sur l'apparition des lésions hépatiques lors de la maladie alcoolique du foie.

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

A avaliação do risco é um processo sistemático pelo qual a possibilidade de dano, a exposição e o próprio risco são identificados e quantificados. A consideração, de que a participação em um estudo é de risco, fundamenta-se no princípio da precaução, que é a garantia da existência de medidas de proteção contra riscos potenciais. De acordo com a gravidade dos eventos adversos, e de sua probabilidade de ocorrência, determina-se se o risco previsto é negligenciável, tolerável ou intolerável. Portanto, a caracterização do risco representa um importante elo entre os dados científicos obtidos nos diferentes estudos e as tomadas de decisões, ao monitoramento e à comunicação do risco. O objetivo deste estudo é avaliar os riscos previstos de eventos adversos gastrintestinais em projetos de pesquisa em seres humanos na área farmacológica, realizados no Hospital de Clínicas de Porto Alegre (HCPA), através da análise do Termo de Consentimento Livre e Esclarecido (TCLE), do manual do pesquisador e do projeto. Realizou-se um estudo transversal, com unidade de observação nos eventos adversos (EAs) gastrintestinais, através do levantamento de risco de projetos de pesquisa farmacológica, com patrocínio privado, submetidos e aprovados pelo Comitê de Ética em Pesquisa (CEP) do HCPA, no ano de 2004. De 58 projetos analisados, identificou-se 9734 referências de riscos de EAs gerais, sendo que 1463 (15,0%) eram gastrintestinais. Destas, 181 (12,4%) aparecem somente no TCLE, desprovida de embasamento teórico; já 1047 (71,6%) estão descritas nos documentos não disponibilizados ao participante, informação não compartilhada, tendo embasamento teórico; e apenas 235 referências de riscos, que representam 16,0% dos riscos gastrintestinais totais, como informação compartilhada e documentada, para o participante e pesquisador, com embasamento teórico. Essas 1463 referências de riscos de EAs gastrintestinais foram padronizadas, fazendo-se uso do Código Internacional de Doenças, décima revisão (CID 10), obtendo-se 170 tipos diferentes de riscos. Os riscos com maior repetição de referência nos projetos foram: náusea e vômitos 14,1%; alteração do hábito intestinal 6,5%; aumento dos níveis de transaminases e da desidrogenase lática 5,7%; outras dores abdominais e as não especificadas 4,9%. Quanto à gravidade, dos 170 tipos de riscos, obteve-se 65 (38,2%) graves, 52 (30,6%) moderados, 30 (17,6%) leves e 23 (13,5%) múltipla classificação. Todos os documentos relativos ao projeto de pesquisa deveriam conter a descrição e quantificação dos riscos importantes, seja pela alta gravidade ou freqüência associada. No TCLE, parte dos riscos estavam descritos, porém desprovidos de uma quantificação e caracterização adequadas. O manual apresentava as informações sobre os riscos, mas de forma dispersa ao longo do documento, levando a uma dificuldade de utilização desses dados nas intervenções propostas. Nos projetos analisados, observa-se a falta de homogeneidade e padronização para se expressar adequadamente os riscos já ocorridos em estudos prévios. Isso demonstra a importância da leitura atenta de toda documentação encaminhada para avaliação pelo CEP, visando a proteção ativa dos sujeitos da pesquisa. / Risk evaluation is a systematic process whereby damage possibility, exposure and the risk itself are identified and quantified. The consideration that the participation in a study is risky is founded on the precaution principle, i.e., the warranty of existing protection measures against potential risks. According to the severity of the adverse events and of its occurrence probability, one determines if the foreseen risk is negligible, tolerable or intolerable. Therefore, risk characterization represents an important link between the scientific data obtained from the different studies and the decision-makings, to monitoring and to risk communication. The objective of this study is evaluating the foreseen risks of gastrointestinal adverse events (AEs) in research projects with human beings in the pharmacological field carried out at Hospital de Clínicas de Porto Alegre – HCPA by means of the Informed Consent Form – ICF, of the researcher brochure and of the Research Protocol. A transversal study was carried out with an observation unit in the gastrointestinal AEs, through the survey of risk of projects of clinical trial with private sponsorship submitted to and approved by the Research Ethics Committee – REC of the HCPA in 2004. Out of 58 analyzed protocols were identified 9734 risk references of general AEs, being 1463 (15.0%) gastrointestinal. Out of these, 181 (12.4%) appear on the ICF only, deprived of theoretical basis; while 1047 (71.6%) are described in documents non available for the participant, non-shared information, with theoretical basis; only 235 risk references that represent 16.0% of the total gastrointestinal risk, as shared and documented information for the participant and the researcher, having theoretical basis. These 1463 risk references of gastrointestinal AEs were standardized by making use of the International Code of Diseases – 10th Revision –, and 170 different risk types were obtained. The risks with more reference repetition in the protocols were: nausea and vomit 14.1%; alteration of intestinal habit 6.5%; increase of the levels of transaminases and of lactic dehydrogenase 5.7%; abdominal pain 4.9%. As to the severity, out of the 170 risk types, 65 (38.2%) are severe, 52 (30.6%) moderate, 30 (17.6%) soft and 23 (13.5%) of multiple classification. All of the documents regarding the research protocol should contain the description and quantification of the important risks either due to high severity or to frequency. In the ICF, some of the risks were described however deprived of an adequate quantification and characterization. The brochure presented the information about the risks, however in a disperse way over the document leading to a difficult utilization of these data in the proposed interventions. In the analyzed protocols was observed lack of homogeneity and standardization to adequately express the risks that had already occured in previous studies. This observation demonstrates the importance of careful reading of all of the documentation addressed for evaluation by the REC aiming at the active protection of the research subjects.

A avaliação do risco é um processo sistemático pelo qual a possibilidade de dano, a exposição e o próprio risco são identificados e quantificados. A consideração, de que a participação em um estudo é de risco, fundamenta-se no princípio da precaução, que é a garantia da existência de medidas de proteção contra riscos potenciais. De acordo com a gravidade dos eventos adversos, e de sua probabilidade de ocorrência, determina-se se o risco previsto é negligenciável, tolerável ou intolerável. Portanto, a caracterização do risco representa um importante elo entre os dados científicos obtidos nos diferentes estudos e as tomadas de decisões, ao monitoramento e à comunicação do risco. O objetivo deste estudo é avaliar os riscos previstos de eventos adversos gastrintestinais em projetos de pesquisa em seres humanos na área farmacológica, realizados no Hospital de Clínicas de Porto Alegre (HCPA), através da análise do Termo de Consentimento Livre e Esclarecido (TCLE), do manual do pesquisador e do projeto. Realizou-se um estudo transversal, com unidade de observação nos eventos adversos (EAs) gastrintestinais, através do levantamento de risco de projetos de pesquisa farmacológica, com patrocínio privado, submetidos e aprovados pelo Comitê de Ética em Pesquisa (CEP) do HCPA, no ano de 2004. De 58 projetos analisados, identificou-se 9734 referências de riscos de EAs gerais, sendo que 1463 (15,0%) eram gastrintestinais. Destas, 181 (12,4%) aparecem somente no TCLE, desprovida de embasamento teórico; já 1047 (71,6%) estão descritas nos documentos não disponibilizados ao participante, informação não compartilhada, tendo embasamento teórico; e apenas 235 referências de riscos, que representam 16,0% dos riscos gastrintestinais totais, como informação compartilhada e documentada, para o participante e pesquisador, com embasamento teórico. Essas 1463 referências de riscos de EAs gastrintestinais foram padronizadas, fazendo-se uso do Código Internacional de Doenças, décima revisão (CID 10), obtendo-se 170 tipos diferentes de riscos. Os riscos com maior repetição de referência nos projetos foram: náusea e vômitos 14,1%; alteração do hábito intestinal 6,5%; aumento dos níveis de transaminases e da desidrogenase lática 5,7%; outras dores abdominais e as não especificadas 4,9%. Quanto à gravidade, dos 170 tipos de riscos, obteve-se 65 (38,2%) graves, 52 (30,6%) moderados, 30 (17,6%) leves e 23 (13,5%) múltipla classificação. Todos os documentos relativos ao projeto de pesquisa deveriam conter a descrição e quantificação dos riscos importantes, seja pela alta gravidade ou freqüência associada. No TCLE, parte dos riscos estavam descritos, porém desprovidos de uma quantificação e caracterização adequadas. O manual apresentava as informações sobre os riscos, mas de forma dispersa ao longo do documento, levando a uma dificuldade de utilização desses dados nas intervenções propostas. Nos projetos analisados, observa-se a falta de homogeneidade e padronização para se expressar adequadamente os riscos já ocorridos em estudos prévios. Isso demonstra a importância da leitura atenta de toda documentação encaminhada para avaliação pelo CEP, visando a proteção ativa dos sujeitos da pesquisa. / Risk evaluation is a systematic process whereby damage possibility, exposure and the risk itself are identified and quantified. The consideration that the participation in a study is risky is founded on the precaution principle, i.e., the warranty of existing protection measures against potential risks. According to the severity of the adverse events and of its occurrence probability, one determines if the foreseen risk is negligible, tolerable or intolerable. Therefore, risk characterization represents an important link between the scientific data obtained from the different studies and the decision-makings, to monitoring and to risk communication. The objective of this study is evaluating the foreseen risks of gastrointestinal adverse events (AEs) in research projects with human beings in the pharmacological field carried out at Hospital de Clínicas de Porto Alegre – HCPA by means of the Informed Consent Form – ICF, of the researcher brochure and of the Research Protocol. A transversal study was carried out with an observation unit in the gastrointestinal AEs, through the survey of risk of projects of clinical trial with private sponsorship submitted to and approved by the Research Ethics Committee – REC of the HCPA in 2004. Out of 58 analyzed protocols were identified 9734 risk references of general AEs, being 1463 (15.0%) gastrointestinal. Out of these, 181 (12.4%) appear on the ICF only, deprived of theoretical basis; while 1047 (71.6%) are described in documents non available for the participant, non-shared information, with theoretical basis; only 235 risk references that represent 16.0% of the total gastrointestinal risk, as shared and documented information for the participant and the researcher, having theoretical basis. These 1463 risk references of gastrointestinal AEs were standardized by making use of the International Code of Diseases – 10th Revision –, and 170 different risk types were obtained. The risks with more reference repetition in the protocols were: nausea and vomit 14.1%; alteration of intestinal habit 6.5%; increase of the levels of transaminases and of lactic dehydrogenase 5.7%; abdominal pain 4.9%. As to the severity, out of the 170 risk types, 65 (38.2%) are severe, 52 (30.6%) moderate, 30 (17.6%) soft and 23 (13.5%) of multiple classification. All of the documents regarding the research protocol should contain the description and quantification of the important risks either due to high severity or to frequency. In the ICF, some of the risks were described however deprived of an adequate quantification and characterization. The brochure presented the information about the risks, however in a disperse way over the document leading to a difficult utilization of these data in the proposed interventions. In the analyzed protocols was observed lack of homogeneity and standardization to adequately express the risks that had already occured in previous studies. This observation demonstrates the importance of careful reading of all of the documentation addressed for evaluation by the REC aiming at the active protection of the research subjects.

M.A. / Irritable bowel syndrome [IBS] has been described as a chronic relapsing condition, characterised by a change in bowel habit and abdominal pain, that cannot be explained by an organic disease. Some research indicates that IBS may be psychogenic in origin, however, the aetiology of this complex syndrome is still unclear. Some researchers have postulated that IBS is primarily a motility disorder of the gut, while others have indicated that the symptoms of IBS are mediated by the central nervous system. Thus it is not surprising that the care of patients with IBS poses a particular challenge to physicians, especially because of its biologic and symptomatic heterogeneity and, particularly for patients with refractory symptoms, its association with psychological disturbances. The literature study indicates that there that there may be a possible connection between the ingestive disorders, the menstrual cycle fluctuations associated with premenstrual dysphoric disorder and IBS. All three of these disorders also appear to be mediated, to some extent, by the neurotransmitter serotonin. In terms of these suggested correlations one of the aims of this study was to determine whether blood-serotonin levels significantly influence the symptomatology of IBS. Extensive literature exists documenting the potential role that serotonin plays in gastrointestinal functioning. However, none of the existing studies refer specifically to blood-serotonin levels. Thus the present study attempted to address this problem. A second aim of the present study was to determine the possible serotonergic connection in the ingestive disorders and premenstrual dysphoric disorder in women with IBS. All the subjects were required to go for a blood test in order to determine whether their serotonin levels were low, normal, or high. In addition, three self-report questionnaires were used in this investigation. The Irritable Bowel Syndrome Client Questionnaire; The Eating Disorder Inventory -2, of which four subscales out of 11 subscales were included, namely the Drive for Thinness, Bulimia, Body Dissatisfaction and Introceptive Awareness subscales; and the Premenstrual Assessment Form, of which six subscales out of 18 were included, namely Endogenous Depressive Features, Atypical Depressive Features, Signs of water Retention, General Physical Discomfort, Autonomic Physical Changes and Miscellaneous Physical Changes. In order to address the above mentioned aims, research was conducted at the Research and Counselling Centre for Psychogastroenterology at the Rand Afrikaans University. The Research and Counselling Centre for Psychogastroenterology is a facility developed to investigate the psychological constituents of IBS. Researchers at the centre are aiming to explore the multidimensional components of IBS with the purpose of gaining some understanding into the development and maintenance of this syndrome. A variety of topics are being investigated at the Research and Counselling Centre for Psychogastroenterology, including the role that stress, depression and coping styles play in IBS. Initially a sample group of (N = 60) women with IBS were selected for this research from a population of South Africans who were referred from gastroenterologists and general practitioners to the Centre for Gastroenterology at the Rand Afrikaans University. A number of women (N = 40) without IBS, from the north eastern suburbs of Johannesburg, were also asked to participate in this study in order to compile the comparison group.

<p>Vitamin E is a natural lipophilic antioxidant contains eight structurally related forms, i.e., α-, β-, γ-, δ-tocopherols (αT, βT, γT, and δT) and corresponding tocotrienols. Recent research indicates that vitamin E forms are differentially metabolized to various carboxychromanols. Some these vitamin E metabolites have been shown to exhibit strong anti-inflammatory and anticancer effects, yet little is known about their bioavailability. Without this knowledge, it is impossible to assess the role of vitamin E metabolism in biological functions of vitamin E forms and their protective effects on chronic diseases. While αT and γT appear to improved gut health, the underlying mechanisms are not well understood. Furthermore, specific forms of vitamin E such as γT have been reported to have cancer-preventing effects, but their anticancer efficacy is relatively modest. For these reasons, this dissertation focused on the characterization of the pharmacokinetic formation of vitamin E metabolites after supplementation, and the investigation of the underlying mechanisms of the protective effect of vitamin E forms, αT and γT, on gut health, as well as anticancer efficacy of the combination of aspirin and γT on carcinogen-induced colon tumorigenesis.</p><p><br></p><p>The first project focuses on characterizing the pharmacokinetic formation of vitamin E metabolites after single dose supplementation of γ-tocopherol-rich mixed tocopherol (γTmT) and δ-tocotrienol (δTE). With our recently developed LC/MS/MS assay for quantifying vitamin E metabolites, we can simultaneously quantify the level of short-chain, long-chain, and sulfated carboxychromanols in plasma, urine, and fecal samples of supplemented animals. In this study, we investigated the pharmacokinetics including excretion of vitamin E forms and the formation of their metabolites after a single dose intragastric administration of tocopherols and tocotrienols in rats. We also measured vitamin E metabolites in the serum obtained from healthy humans after gT supplementation. In the plasma of rat, the pharmacokinetic profiles of γT and δTE are described as the following: γT, Cmax = 25.6 ± 9.1 μM, Tmax = 4 h; δTE, Cmax = 16.0 ± 2.3 μM, Tmax = 2 h. Sulfated CEHCs and sulfated 11’-COOHs were the predominant metabolites in the plasma of rat with Cmax of 0.4-0.5 μM (Tmax ~ 5-7 h) or ~0.3 μM (Tmax at 4.7 h), respectively. In 24-h urine, 2.7% of γT and 0.7% of dTE were excreted as conjugated CEHCs, the major identified urinary metabolites. In the feces, 17-45% of supplemented vitamers were excreted as un-metabolized forms and 4.9-9.2% as metabolites. The majority of metabolites excreted in feces were unconjugated carboxychromanols, among which 13’-COOHs constituted ~50% of total metabolites. Interestingly, 13’-COOHs derived from δTE were 2-fold higher than 13’-COOH from γT. Unlike rats, γ-CEHC is the predominant metabolites found in human plasma, although 11’-COOHs and 13’-COOHs (sulfated and unconjugated) were elevated by >20 folds responding to γT supplement. In this study, we found that tocopherols and tocotrienols, when taken as supplements, are mainly excreted as un-metabolized forms and long-chain carboxychromanols in feces. High fecal availability of 13’-COOHs may contribute to modulating effects on gut health.</p><p><br></p><p>The second project of my dissertation investigated the effect of vitamin E forms, αT and γT, on intestinal barrier function in a cellular model and a mouse colitis model. Inflammatory bowel diseases (IBD) are chronic idiopathic inflammatory conditions characterized by disruption of intestinal barrier integrity. Previous studies by others and us had demonstrated that vitamin E forms, αT and γT, can protect against chemical-induced colitis in animal models. However, the role of these vitamin E forms on intestinal barrier function has not been studied. Herein, we investigated the potential protective effects of vitamin E forms, αT and γT, on intestinal barrier function in a Caco-2 colon epithelial cell model and a dextran sodium sulfate (DSS)-induced colitis mouse model. In Caco-2 cells, pretreatment with 25mM αT and γT attenuated Caco-2 monolayer barrier dysfunction induced by 10 ng/mL TNF-α/IFN-γ, suggesting that these vitamin E forms protect intestinal barrier integrity in this cellular model. In male BALB/c mice, the supplementation of αT (0.05%) or γTmT (0.05%) when given 3 weeks before DSS treatment or at the same time as DSS treatment alleviated DSS-induced fecal bleeding and diarrhea symptoms in mice, and attenuated colon inflammation and colitis-associated damages. Additionally, αT and γTmT supplementation attenuated DSS-induced intestinal barrier dysfunction, as indicated by improving the level of occludin, a tight junction protein, in the colon and reducing lipopolysaccharide-binding protein (LBP) in the plasma. Furthermore, gut microbiota analysis demonstrated that αT and γTmT supplementation could modulate intestinal microbiome composition in mice with DSS treatment. DSS treatment reduced the relative abundance of Lachnospiraceae compared to healthy mice, and supplementation of αT and γT partially reversed this effect. Interestingly, the family Lachnospiraceae has been reported to decrease in IBD patients. Our study demonstrated the protective effects of vitamin E forms on intestinal barrier integrity in a cell-based model and a colitis model in mice. Furthermore, we demonstrated that these vitamin E forms caused favorable changes in the intestinal microbial population under colitis condition.</p><p><br></p><p>The third project of my dissertation evaluated the anticancer efficacy of the combination of aspirin and γT using an azoxymethane (AOM)-induced and colitis-promoted colon tumorigenesis mouse model. Extensive inflammation in the colon promotes the development of colorectal cancer (CRC). Eicosanoid production by pro-inflammatory enzymes, cyclooxygenases (COX-1 and COX-2) and 5-lipoxygenase (5-LOX) play a critical role in the initiation, progression, and invasion of CRC. Thus, nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, have been recommended for chemoprevention of CRC. However, long-term use of aspirin can cause many side effects, and the anticancer activity of aspirin is very modest. Previously, we have demonstrated that the combination of γT with aspirin prolonged the anti-inflammatory activity of aspirin and alleviated aspirin-associated adverse effects in a carrageenan-induced inflammation model in rats. Additionally, we found that the combination of γT and aspirin has stronger anticancer activity than aspirin or γT alone against HCT-116 human colorectal carcinoma cells. Therefore, we examined the anticancer effect of the combination of 0.025% aspirin and 0.05% γT against AOM-induced and DSS-promoted tumorigenesis in mice. In this study, we have found that the combination of aspirin and γT, but not aspirin or γT alone, suppressed colon tumorigenesis in mice, as indicated by 40% and 50% reduction in the multiplicity of total polyps (P < 0.05) and large adenomatous polyps (>2mm2, P < 0.05), respectively. More strikingly, the combination of aspirin and γT reduced the overall tumor area by 60% (P < 0.05). Noteworthy, the supplementation of γT also alleviated aspirin-induced stomach lesion and appeared to modulate intestinal microbial composition. Our study demonstrated that the combination of aspirin and γT has stronger anticancer activity than aspirin or γT alone while alleviates aspirin-associated adverse effect, suggesting that the combination of γT and aspirin is a more effective and safer chemopreventive agent for CRC than aspirin alone.</p>

L'opinion générale est que les ulcères sont rares pendant l'enfance, les lésions provoquées par Helicobacter pylori (H. pylori) ne se produisant que des décennies après l'acquisition de l'infection. L’infection par cette bactérie est en outre moins fréquente chez les enfants dans les pays développés par rapport aux adultes. Par ailleurs, l’usage chronique de médicaments gastro-toxiques est peu fréquent dans cette tranche d’âge. Cependant, plusieurs études ont montré qu’environ 1/10 des enfants référés pour des symptômes de dyspepsie en Europe et infectés par H. pylori présentent un ulcère gastrique ou duodénal, mais aussi que la fréquence de ces lésions chez les enfants non infectés n’est pas nulle.<p>Afin de déterminer la fréquence des ulcères gastriques et duodénaux et des érosions, nous avons commencé par réaliser une étude prospective avec la participation de 19 centres répartis dans 14 pays d'Europe. Tous les enfants référés pour une endoscopie haute ont été recrutés durant une brève période de 1 mois. Parmi les 694 enfants inclus, 56 (8,1%) avaient soit des ulcères (ulcère gastrique 17/56, 30% - ulcère duodénal 7/56, 13%) soit des érosions (érosions gastriques 21/56, 37% - érosions duodénales 9/56, 16% - érosions gastriques et duodénales 2/56, 4%). Cette étude a permis de confirmer que la fréquence des lésions augmente avec l’âge, les enfants atteints de lésions étant significativement plus âgés que les témoins. En effet, les lésions ont surtout été observées chez les enfants dans la deuxième décade de vie. Une infection par H. pylori était présente seulement chez 15 des 56 enfants (27%), un médicament gastro-toxique avait été utilisé chez 13/56 (23%), une maladie inflammatoire chronique de l’intestin était présente chez 7/56 (13%) et une polyarthrite juvénile chez 2/56 (4%, plus d'un facteur de risque présent dans la plupart des cas). Aucun facteur de risque n’a pu être démontré chez 24/56 enfants (43%), une proportion beaucoup plus élevée que celle initialement attendue.<p>Nous avons ensuite réalisé une étude cas-témoins prospective et multicentrique (12 centres participants). Tous les patients avec une lésion érosive ou ulcérée de la muqueuse gastroduodénale ont été inclus avec deux témoins appariés pour l’âge, le centre et la période. Sept cent trente-deux patients (244 cas dont 153 avec seulement des érosions et 91 avec un ou des ulcères, 488 témoins) ont été inclus. Les enfants qui avaient reçu un antibiotique, un inhibiteur de la pompe à proton ou un anti-H2 durant les 4 semaines précédant l’endoscopie ont été exclus de l’analyse statistique parce que ces médicaments influencent la détermination<p>7<p>du statut H. pylori et la gravité des lésions (42 cas et 98 témoins). Nos résultats montrent que, chez les enfants, l'infection à H. pylori est un facteur de risque pour les ulcères duodénaux et les érosions duodénales, mais pas pour les lésions gastriques. Le sexe masculin, la consommation d'AINS, les maladies rénales chroniques et le tabagisme sont d'autres facteurs de risque indépendants de lésions érosives ou d’ulcères gastroduodénaux. Cependant, aucun facteur de risque identifiable n’a été retrouvé dans une grande proportion d'enfants (97/202, 48.0%) ce qui confirme les résultats de notre première étude.<p>Chez les adultes également la proportion d’ulcères sans infection à H. pylori et sans prise d’AINS est en augmentation ces dernières années tout en restant plus faible que chez l’enfant. La fréquence des ulcères gastriques et duodénaux avec un diamètre d’au moins 5 mm a été comparée, dans notre centre et dans un centre d’endoscopie adulte situé dans la même région de Bruxelles, sur une période de deux ans. Ces données montrent que les ulcères sont moins fréquents chez les enfants que chez les adultes (20/1279 enfants avec endoscopie haute - 1,6% vs adultes 58/1010 - 5,7%, OR 0,30, 95%CI 0,10-0.86, p = 0,02) et surtout moins fréquemment associés à une infection par H. pylori (8/20 vs 40/58, OR 0,26, 95%CI 0,16- 0.78, p <0,0001).<p>Comme l’activation de la réponse immunitaire locale est inefficace pour éliminer l’infection par H. pylori et serait plutôt impliquée dans la pathogenèse des lésions de la muqueuse, nous avons comparé la réponse immunitaire muqueuse des lymphocytes T et les réponses naïves chez les enfants et chez les adultes infectés par H. pylori ainsi que chez des témoins non infectés appariés pour l’âge.<p>Dans une première étude, nous avons obtenu des biopsies de la muqueuse antrale chez 43 patients dyspeptiques (12 enfants, 31 adultes). Les concentrations de cytokines libérées dans le milieu de culture et la densité de cellules CD3+, CD25+ et CD69+ ont été évaluées par cytométrie en flux. Le nombre de cellules sécrétant de l’interféron-γ (IFN-γ), de l’interleukine-4 (IL-4) et de l’IL-10 a été mesuré par ELISPOT. Les données obtenues montrent que l’augmentation de la sécrétion d'IFN-γ et l’élévation du nombre de cellules secrétant de l’IFN-γ au niveau de la muqueuse antrale lors d’une infection par H. pylori sont plus faibles chez les enfants que chez les adultes.<p>8<p>Dans une seconde étude, nous avons comparé l’infiltrat inflammatoire de la muqueuse antrale dans différents groupes d’âge (moins de 8 ans, 8 à 17 ans, 18 à 55 ans) de patients successifs infectés par H. pylori et des témoins appariés pour l’âge. Nous avons montré une corrélation entre l'âge et la densité de neutrophiles, de cellules CD3+ et de CD8+, mais pas de cellules CD20+. Le recrutement des neutrophiles dans la muqueuse antrale est plus faible chez les enfants et apparaît corrélé avec une plus faible activation du facteur de transcription NF-kB (déterminé par immunohistochimie et par EMSA) dans cette même muqueuse. L’infiltrat inflammatoire et l’activation du NF-kB sont légèrement (mais non significativement) plus intenses en cas d’infection par une souche plus virulente (facteur de virulence cagA). Ces souches cagA+ sont retrouvées en proportion équivalente dans les différents groupes d’âge. Par contre, la charge bactérienne, mesurée par un score semi-quantitatif en histologie, n’influence pas l’intensité de l’infiltrat inflammatoire.<p>En conclusion :H. pylori reste un facteur étiologique majeur pour les ulcères et les érosions duodénales chez l’enfant, mais pas pour les lésions gastriques dans les pays à faible prévalence de l'infection et la proportion de lésions associées à une infection est plus faible que chez les adultes. Aucun facteur d’exposition connu ne peut être associé aux lésions endoscopiques dans la moitié des cas, ce qui justifiera des études ultérieures pour identifier d’autres causes exogènes ou endogènes à ces lésions.<p>La réponse immunitaire de l’hôte est impliquée dans la pathogenèse des lésions gastroduodénales associées à une infection par H. pylori. Or il a été démontré dans les travaux faisant l’objet de cette thèse que cette réponse immunitaire est plus faible chez l’enfant que chez l’adulte pour certains facteurs (cytokines Th1, immunité humorale, recrutement des polynucléaires et des lymphocytes au niveau muqueux, activation du facteur de transcription NF-κB). D’autres études confirment la plus faible réponse humorale et Th1, mais également Th17 ainsi qu’une activation plus intense des Treg. Les cytokines ou les voies de signalisation responsables de cette réponse immunitaire plus faible restent inconnues, ce qui ouvre la voie à d’autres investigations. / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished