Abstract Atherosclerosis is a multifactorial disease with numerous genes and environmental factors affecting its intiation and progression. During the past years many candidate genes for atherosclerosis have been suggested, and it has also become evident that the immune system plays a part in atherogenesis. Early atherosclerotic changes can be effectively detected by measuring carotid artery intima-media thickness (IMT). In the present study the associations between IMT and polymorphisms of three candidate genes for atherosclerosis were studied: endothelial nitric oxide synthase (eNOS), apolipoprotein E (apoE) and paraoxonase-1 (PON1). To assess the role of immunological factors determining carotid atherosclerosis, CRP and circulating autoantibodies to oxidised LDL were studied in relation to IMT. The study population consisted of 519 hypertensive and 526 control subjects from a middle-aged population in Oulu, Finland. The results showed that the investigated polymorphisms of eNOS and PON1 genes were not associated with IMT, suggesting that these polymorphisms are not major risk factors for atherosclerosis in the general Caucasian population. A significant interaction between the apoE polymorphism and smoking in relation to IMT was observed among men, indicating that carriers of the ε4 allele may be particularly prone to the atherogenic effects of smoking. This interaction was especially clear in hypertensive subjects. CRP was strongly associated with IMT before adjusting for confounding factors. After the adjustment, this association diasppeared. The finding suggests that instead of early atherosclerosis CRP may be related to the later phases of the disease. This may partly explain the strong correlation between CRP and future cardiovascular events. IgM type of autoantibodies binding to oxidised LDL were inversely associated with IMT, and this finding remained after adjusting for previously known risk factors for atherosclerosis, implying a possible protective role for these antibodies in atherogenesis.

No description available.

Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality in the United States. It is also well recognized that the incidence of CVD is substantially increased in postmenopausal women due to the loss of estrogen. Experimental and clinical data support vascular protective effects of estrogen by various mechanisms. However, administration of estrogen is also associated with an increased incidence of heart disease which limits its therapeutic potential. Given the demonstrated risks of conventional estrogen therapy, a search for novel, cost-effective, alternative vasoactive agents for prevention of CVD is of major importance in the effort to decrease the burden of CVD morbidity. Genistein, a major soy isoflavone, may be one of those alternative agents because of its selective affinity to estrogen receptor-beta and various beneficial effects on CVD. However, the mechanism of the cardioprotective effects of genistein is still unclear. The objectives of this study were (1) to investigate the effect of genistein on the expression of endothelial nitric oxide synthase (eNOS) both in vitro and in vivo; (2) to define the mechanism by which genistein regulates eNOS expression; and, (3) to examine whether genistein protects against tumor necrosis factor-alpha (TNF-α)-induced apoptosis in human aortic endothelial cells (HAECs). The results demonstrated that genistein, at physiologically achievable concentrations (1-10 μM) in individuals consuming soy products, enhanced the expression of eNOS protein and subsequently elevated nitric oxie (NO) synthesis in both HAECs and human umbilical vein endothelial cells, concomitant with the increased eNOS mRNA expression (2.6-fold of control) and eNOS promoter activity, suggesting that genistein activates eNOS transcription. Furthermore, dietary supplementation of genistein to spontaneously hypertensive rats restored aortic eNOS levels, improved aortic wall thickness, and alleviated hypertension, confirming the biological relevance of the in vitro findings. However, the effects of genistein on eNOS and NO were not mediated by activation of estrogen signaling, mitogen-activated protein kinase, phosphatidylinositol 3-kinase/Akt kinase, protein kinase C or inhibition of typrosine kinases, but possibly through activating the cAMP/protein kinase A/cAMP responsive elemant binding protein pathway. These data suggest that genistein has direct genomic effects on the vascular wall that are unrelated to its known actions, leading to increase in eNOS expression and NO synthesis, thereby improving vascular homeostasis. We also found that genistein (5-10 μM) significantly inhibited TNF-α-induced apoptosis in HAECs as determined by caspase-3 activation, apoptotic cell detection and DNA laddering. The anti-apoptotic effect of genistein was associated with an enhanced expression of anti-apoptotic Bcl-2 protein and its promoter activity that was ablated by TNF-α. Moreover, this anti-apoptotic effect of genistein was not mediated by extracellular signal-regulated kinase 1/2, protein kinase A, or estrogen receptor. However, inhibition of p38 mitogen-activated protein kinase (p38) by SB203580 completely abolished the cytoprotective effect of genistein, suggesting that genistein acted through the p38-dependent pathway. Accordingly, stimulation of HAECs with genistein resulted in rapid and dose-dependent activation of p38. Unlike TNF-α which specifically activated p38α, genistein selectively induced phosphorylation of p38β, suggesting that p38β, but not p38α, is essential for the cytoprotective effect of genistein. These findings provide the evidence that genistein acts as a survival factor for vascular ECs to protect cells against apoptosis via activation of p38β. Taken together, the resuls of the present study suggest that genistein can act directly on vascular ECs, improves endothelium homeostasis by promoting eNOS expression and endothelial-derived NO synthesis through activating the cAMP/PKA/CREB cascade, and protects against TNF-α-induced apoptosis via activation of p38 β. These data potentially provide a basic mechanism underlying the physiological effects of genistein in the vasculature. / Ph. D.

Thesis (MScMedSc (Biomedical Sciences. Medical Physiology))--University of Stellenbosch, 2009. / In the heart, endothelial nitric oxide synthase (eNOS) is regarded as the most important constitutively expressed enzymatic source of nitric oxide (NO), a major cardiac signalling molecule. On the whole, NO is regarded as a cardioprotective molecule. The role of eNOS during ischaemia / hypoxia is controversial; however, it is generally accepted that ischaemia / hypoxia results in increased cardiac NO production. Most studies focus either on the whole heart or isolated cell models. As yet, no study has compared findings with regard to NO metabolism in these two distinct models, in a single study. We hypothesise that observations in a whole heart model with regard to increased NO production and eNOS involvement in ischaemia are the result of events on cellular level and that the increase in NO production observed during hypoxia in cardiomyocytes and endothelial cells is at least in part due to the increase in expression and / or activation of eNOS. Furthermore, we hypothesize that these effects are mediated via the PI3-K / PKB pathway. We aimed to measure and compare NO-production and eNOS expression and activation in the whole heart and isolated cardiac cells and measure PKB expression and activation in the cells under normoxic and ischaemic / hypoxic conditions. We also aimed to determine the effects of PI3-K / PKB pathway inhibition on NO production and eNOS expression and activation in isolated cardiac cells under normoxic and hypoxic conditions. Adult rat hearts were perfused and global ischaemia induced for 15 and 20 min. Tissue homogenates of perfused hearts were used for the measurement of nitrites and determination of expression and activation of eNOS. Expression of eNOS in the heart was also determined by immunohistochemical (IHC) analysis. Cardiomyocytes were isolated from adult rat hearts by collagenase-perfusion, and adult rat cardiac microvascular endothelial cells (CMEC) purchased commercially. In the cells, hypoxia was induced by covering cell pellets with mineral oil for 60 min. Cell viability was determined by trypan blue and propidium iodide (PI) staining and intracellular NO production measured by FACS analysis of the NO-specific probe, DAF-2/DA and by measurement of nitrite levels (Griess reagent). Results show that in ischaemic hearts, nitrite production increased by 12 % after 15 min ischaemia and 7 % after 20 min ischaemia. Total eNOS expression remained unchanged (Western Blot and IHC) and activated eNOS (phospho-eNOS Ser1177) increased by 38 % after 15 min ischaemia and decreased by 43% after 20 min ischaemia. In the cells, both viability techniques verified that the hypoxia-protocol induced significant damage. In isolated cardiomyocytes, NO-production increased 1.2-fold (by DAF-2/DA fluorescence), total eNOS expression increased 2-fold and activated eNOS increased 1.8-fold over control. In CMECs, NO-production increased 1.6-fold (by DAF-2/DA fluorescence), total eNOS increased by 1.8- fold and activated eNOS by 3-fold. With regards to our PI3-K / PKB investigations, results showed an increase of 84 % and 88 % in expression vii and activation of PKB (phospho Ser473) in hypoxic cardiomyocytes, respectively. In hypoxic CMECs, there was no change in PKB expression but there was a 69 % increase in phosphorylated PKB. NO production in wortmannin-treated hypoxic cardiomyocytes decreased by 12 % as compared to untreated hypoxic cells. In treated hypoxic CMECs, NO production decreased by 58 % as compared to untreated hypoxic cells. Treatment with wortmannin did not change the expression of eNOS protein in the cardiomyocytes, however, activated eNOS decreased by 41 % and 23 % under baseline and hypoxic conditions in treated cells respectively. There was a significant increase in NO production after exposure to O2 deficient conditions in all models investigated, a trend similar to what previous studies in literature found. However, the source of this NO is not fully understood although it has been discovered that NOS plays a role. Our data reveals similar trends in 15 min ischaemia in whole hearts and 60 min hypoxia in the cells; however, the trends observed at 20 min ischaemia are in conflict with our cell data (i.e. decrease in activated eNOS). This may be due to the severity of the ischaemic insult in whole hearts and/or the presence of other cell types and paracrine factors in the whole heart. Hypoxia increased the activation of PKB in the isolated cardiac cells. Inhibition of the PI3-K / PKB pathway reduced NO production and hypoxia-induced eNOS activation in cardiomyocytes. In conclusion, we have, for the first time, demonstrated that the increase in NO production during hypoxia is due (at least in part) to an increase in eNOS phosphorylation at Ser1177 and that this is mediated via the PI3-K / PKB pathway.

Há décadas a exposição ao mercúrio é alvo de estudos toxicológicos devido ao alto potencial de danos a saúde humana. Na região amazônica os primeiros estudos reportavam a exposição ocupacional pelo uso nos garimpos de ouro, entretanto recentemente destacam-se os estudos relacionados a exposição ambiental que ocorre na região decorrente do consumo de peixes contaminados com mercúrio. Muitos estudos se concentram em populações ribeirinhas residentes na região do rio Tapajós, onde o consumo de peixes é frequente e o metil-mercúrio (MeHg) contido nos peixes é o responsável pela exposição dessas pessoas ao metal. O MeHg apresenta efeitos tóxicos relevantes sobre o sistema cardiovascular, e muitos grupos de pesquisa buscam elucidar os mecanismos que expliquem tais efeitos. Alguns estudos apontam uma diminuição significativa na disponibilidade do óxido nítrico (NO) após exposição ao organometal, o que poderia contribuir para uma alteração da fisiologia cardiovascular uma vez que o NO é um modulados desse sistema. O NO é sintetizado pela óxido nítrico sintase endotelial (eNOS) e sua atividade pode ser alterada por vários fatores, dentre eles, os polimorfismos nos genes que codificam essa proteína, são eles: T-786C na região promotora, 27-pb VNTR no intron 4 e Glu298Asp no exon 7. Neste sentido, o presente estudo teve por objetivo avaliar os efeitos dos polimorfismos da eNOS sobre a síntese de NO entre os indivíduos expostos a metilmercúrio. Foram analisadas amostras de sangue de 214 voluntários com idade entre 15 e 84 anos, dos quais 103 homens e 111 mulheres. A concentração de mercúrio no sangue (Hg sangue) total variou de 1,7 a 179,3 µg/L e a concentração plasmática de nitrito variou entre 85,7 e 695,8 M. Foram determinados os valores de pressão arterial sistólica (PAS), pressão arterial diastólica (PAD), índice de massa corporal (IMC) e freqüência cardíaca (FC) de todos os voluntários. A PAS média foi de 119,8 mmHg e a média da PAD foi 71,8 mmHg. O IMC médio foi de 24,5 Kg/m2 e a FC média foi 70,4 batimentos por minuto (bpm). Não foram observadas diferenças entre os grupos, segundo genótipos dos três polimorfismos, quanto às características dos voluntários: idade, PAS, PAD, IMC, FC, Hg sangue e as concentrações plasmáticas de nitrito. Quando os polimorfismos foram estudados isoladamente foi observado que o alelo C na região promotora, o alelo 4b no intron 4 e o alelo Glu no exon 7 apresentaram-se associados a concentrações reduzidas e nitrito plasmático. Quando a população foi estratificada com base na concentração de Hg essa associação desapareceu, provavelmente mascarada pelas altas concentrações do metal. Entretanto quando foram estudados os haplótipos pode ser observada novamente a associação desses mesmos alelos com a diminuição da concentração do nitrito, confirmando os achados iniciais. O haplótipo mais frequente na população combina os alelos selvagens para todos os polimorfismos (T, 4b e G) e o haplótipo menos freqüente combina os alelos variantes. O haplótipo associado à menor concentração plasmática de nitrito combina os alelos selvagens (C, 4b e G), confirmando os primeiros resultados. Essa abordagem haplotípica é muito útil na observação de efeitos mais discretos uma vez que é possível observar os efeitos dos três polimorfismos agindo simultaneamente sobre uma variável, nesse caso o óxido nítrico. O presente estudo sugere que os fatores genéticos exercem grande influência sobre a produção e biodisponibilidade de NO e que esses fatores combinados com a exposição ambiental ao Hg podem agir de maneira sinérgica, aumentando a suscetibilidade aos efeitos cardiotóxicos do metal através da modulação da atividade da eNOS. / The mercury (Hg) exposure has been target of toxicological studies due the high potential of damage to human health. In the Amazon region the first studies reported the occupational exposure due the use in gold mining, however, recently become relevant the studies about the environment exposure due the fish intake in the riparian population. Several studies have been concentrated in the riparian community in the Tapajós river region, where the fish consumption is frequent and the methylmercury content in fish is responsible to exposure of this people. The MeHg presents toxic effects in the cardiovascular system and many researches groups try to elucidate the mechanisms that explain this effects. Some studies report a significant reducing in nitric oxide (NO) production after the Hg exposure, which could contribute to an altered physiology of the cardiovascular system, once the NO is a modulating factor of this system. The NO is produced by the endothelial nitric oxide synthase (eNOS) and its activity can be altered by many factors like polymorphisms in gene that codify this protein, among this: : T-786C in the promoter region, 27-pb VNTR in intron 4 and Glu298Asp in exon 7. In this regard, the present study mean to evaluate the effects of the eNOS polymorphisms over the NO synthesis among the Hg exposed subjects. In this work, the whole blood samples of 214 volunteers were analyzed for determination of Hg concentration, nitrite plasma concentration and genotyping. The age of the volunteers varied between 15 and 84 years old, including 103 men and 111 women. The blood mercury concentration varied between 1.7 and 179.3 µg/L and the nitrite plasma concentration varied between 85.7 and 695.8 M. Was determinate the systolic arterial pressure (SAP), diastolic arterial pressure (DAP), body mass index (BMI) and heart rate (HR). The SAP mean was 119.8 mmHg and the DAP mean was 71.8 mmHg. The BMI mean was 24.5 Kg/m2 and the HR mean was 70.4 beats per minute. There was no difference among the groups of the three polymorphisms according the volunteers characteristics: age, DAP, SAP, BMI, HR, blood Hg concentration and nitrite plasma concentration. When the polymorphisms were observed separately the reduced nitrite plasma concentration was associated with the presence of the alleles: C in promoter region, 4b in intron 4 and G in exon 7, however there is lack of association when the volunteers were grouped according the blood Hg concentration, probably due a mask effect of the high Hg concentration. When these three polymorphisms were observed simultaneously, in analysis of the haplotypes, the association between the same alleles and the nitrite plasma concentration was observed again, confirming the initial findings. The commonest haplotype in the volunteers combine the alleles of the three polymorphisms (T, 4b and G) and the less frequent haplotype combine the three variants alleles. There was an association between the haplotype C, 4b and G and reduced nitrite plasma concentration, according the result of the polymorphisms separately. The haplotype analysis is too interesting to observe discrete effects, once is possible to analyze the effects of the three polymorphisms acting simultaneously above one variable, in this case, nitric oxide production. The present study suggest that genetic factors could exert a relevant influence above the NO production and bioavailability and that this factors combined with environmental Hg exposure can acting synergic, increasing the susceptibility to Hg cardiovascular effects, through the modulation of the eNOS activity.

Orientador: Cristina Antoniali Silva / Banca: Fernando Silva Carneiro / Banca: Carlos Alan Candido Dias Junior / Banca: Graziela Scalianti Ceravolo / Banca: Angela de Castro Resende / Resumo: A redução da reatividade vascular à fenilefrina (PE) em aorta de ratas espontaneamente hipertensas (SHR) ao final da prenhez é dependente de maior produção e/ou maior biodisponibilidade de óxido nítrico (NO), consequente do aumento da fosforilação da enzima óxido nítrico sintase endotelial (eNOS) via PI3K/Akt. A glicosilação do tipo N-acetil-glucosamina (O-GlcNAc) é uma modificação pós-traducional que compete com a fosforilação pelos mesmos sítios de ligação nas proteínas. A O-GlcNAcilação da eNOS em serina1177 leva a redução da sua atividade enquanto a fosforilação leva a sua ativação. Além destes mecanismos, a interação da eNOS com outras proteínas é capaz de regular positiva ou negativamente a sua atividade. O objetivo deste trabalho foi analisar possíveis alterações nos mecanismos de modificação pós-traducional que controlam a ativação da eNOS os quais poderiam contribuir para maior ativação e maior biodisponibilidade de NO observada em artérias de ratas prenhes. Foram avaliados o conteúdo proteico O-GlcNAc e também expressão das enzimas que participam desta modificação, O-GlcNAc transferase (OGT) e O-GlcNAcase (OGA) por Western Blotting e a atividade da OGA por ensaio bioquímico em aorta e em artéria mesentérica (2º ou 3º ramo) de ratas não prenhes (NP) e prenhes (P), normotensas (Wistar) e SHR. Ensaios de Western Blotting foram realizados também para análise da expressão das seguintes proteínas: Cav-1, p-Cav-1, CaM e Hsp90. Realizamos a contagem do número de cavéolas en... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Reduction of vascular reactivity to phenylephrine (PE) in aortaof spontaneously hypertensive rats (SHR) at the end of pregnancy is dependent on higherproduction and/or higerbioavailability of nitric oxide (NO), as a consequence of increased endothelial nitric oxide synthase enzyme (eNOS) phosphorylation,by PI3K/Akt.Glycosylation with O-linked N-acetylglucosamine (O-GlcNAc)is a post-translational modification that competes with phosphorylation by the same binding sites in proteins. O-GlcNAcylation of eNOSon serine siteleads to a reduction in its activity while eNOS phosphorylation leads to its activation. In addition to these mechanisms, the interaction of eNOS with other proteins is able to regulate positively or negatively its activity. The objective of this studywas to analyze possible changes in the mechanisms of post-translational modification that control the eNOS activation, which could contribute to its the greater activation and greater bioavailability of NO observed in arteriesof pregnant rats. The O-GlcNAc-protein content and also the enzymesexpressionthat participate in this modification, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) was assessed by Western Blotting, and OGA activity were evaluated by biochemical assay in the aorta and in the artery mesenteric (2ndor 3rdbranch) of non-pregnant (NP) and pregnant (P), normotensiverats(Wistar) and SHR.Western Blotting assays were also performed for expression analysis of the following proteins: Cav-1, p-Cav-1, CaM and Hsp90. We performed the counting of the number of endothelial caveolaein the aorta and the mesenteric artery in the presence or absence of methyl-β-cyclodextrin (dextrin, 10 mmol/L) by electronicmicroscopy.In functional studies, we evaluated the participation of the OGA enzyme, by inhibition with PugNAc (100 μmol/L) and of the caveolae, using a caveolae disassembler, (Complete abstract electronic access below) / Doutor

1 Univerzita Karlova v Praze 1. lékařská fakulta Některé aspekty patofyziologie plicní arteriální hypertenze a její výskyt v České republice Some aspects of pathophysiology of pulmonary arterial hypertension and its epidemiology in the Czech Republic MUDr. Pavel Jansa Praha 2011 2 Abstract Pulmonary arterial hypertension (PAH) is a group of diseases characterized by a progressive increase of resistance and pressure in pulmonary vascular bed. In all types of PAH the same four pathological processes are reported: vasoconstriction, inflammation, thrombosis and remodelling. The genetic background is essential for the development of PAH. We aimed to investigate the role of polymorphisms of endothelial nitric oxide synthase (eNOS) genes in PAH. We studied 142 PAH patients and 189 healthy subjects. We examined 3 polymorphisms of the eNOS gene, including the Glu298Asp polymorphism, 27-base pair (bp) variable numbers of tandem repeats (VNTR) and -786 T/C promoter gene polymorphism. Prevalence of 27-bp VNTR allele A was higher in patients with PAH compared with healthy controls. Patients with PAH associated with connective tissue diseases had higher prevalence of AA genotype compared with other PAH subgroups. The Glu298Asp polymorphism and -786 T/C polymorphism are not associated with PAH. Thrombotic arteriopathy is...

Endothelial dysfunction is a pathologic state characterized by an altered equilibrium among vasodilatory and antithrombotic mediators and vasoconstrictive and prothrombotic mediators produced by the vascular endothelium. Multiple factors induce impaired production or increased consumption nitric oxide (NO), the key mediator of vascular homeostasis, produced by the nitric oxide synthase enzymes (NOS). Endothelial dysfunction represents one of the initial steps in the development of atherosclerosis, a chronic inflammatory disease of the vascular wall. The inducible enzyme heme oxygenase 1 (HO-1) represents one of the main cellular defense mechanisms against increased oxidative stress and decreased NO bioavailability accompanying endothelial dysfunction and atherosclerosis. We studied the genetic determinants of endothelial dysfunction and atherosclerosis by evaluating the association of the G894T endothelial NOS (eNOS) polymorphism and the HO-1 (GT)n promoter polymorphism with coronary artery atherosclerosis severity and risk profile and their evolution during hypolipidaemic treatment. In addition, we searched for genetic variations in exons 25 and 26 of eNOS gene, encoding the C-terminal part of the protein, deemed crucial for proper enzyme function and the 3'- untranslated region crucial for eNOS...

Há décadas a exposição ao mercúrio é alvo de estudos toxicológicos devido ao alto potencial de danos a saúde humana. Na região amazônica os primeiros estudos reportavam a exposição ocupacional pelo uso nos garimpos de ouro, entretanto recentemente destacam-se os estudos relacionados a exposição ambiental que ocorre na região decorrente do consumo de peixes contaminados com mercúrio. Muitos estudos se concentram em populações ribeirinhas residentes na região do rio Tapajós, onde o consumo de peixes é frequente e o metil-mercúrio (MeHg) contido nos peixes é o responsável pela exposição dessas pessoas ao metal. O MeHg apresenta efeitos tóxicos relevantes sobre o sistema cardiovascular, e muitos grupos de pesquisa buscam elucidar os mecanismos que expliquem tais efeitos. Alguns estudos apontam uma diminuição significativa na disponibilidade do óxido nítrico (NO) após exposição ao organometal, o que poderia contribuir para uma alteração da fisiologia cardiovascular uma vez que o NO é um modulados desse sistema. O NO é sintetizado pela óxido nítrico sintase endotelial (eNOS) e sua atividade pode ser alterada por vários fatores, dentre eles, os polimorfismos nos genes que codificam essa proteína, são eles: T-786C na região promotora, 27-pb VNTR no intron 4 e Glu298Asp no exon 7. Neste sentido, o presente estudo teve por objetivo avaliar os efeitos dos polimorfismos da eNOS sobre a síntese de NO entre os indivíduos expostos a metilmercúrio. Foram analisadas amostras de sangue de 214 voluntários com idade entre 15 e 84 anos, dos quais 103 homens e 111 mulheres. A concentração de mercúrio no sangue (Hg sangue) total variou de 1,7 a 179,3 µg/L e a concentração plasmática de nitrito variou entre 85,7 e 695,8 M. Foram determinados os valores de pressão arterial sistólica (PAS), pressão arterial diastólica (PAD), índice de massa corporal (IMC) e freqüência cardíaca (FC) de todos os voluntários. A PAS média foi de 119,8 mmHg e a média da PAD foi 71,8 mmHg. O IMC médio foi de 24,5 Kg/m2 e a FC média foi 70,4 batimentos por minuto (bpm). Não foram observadas diferenças entre os grupos, segundo genótipos dos três polimorfismos, quanto às características dos voluntários: idade, PAS, PAD, IMC, FC, Hg sangue e as concentrações plasmáticas de nitrito. Quando os polimorfismos foram estudados isoladamente foi observado que o alelo C na região promotora, o alelo 4b no intron 4 e o alelo Glu no exon 7 apresentaram-se associados a concentrações reduzidas e nitrito plasmático. Quando a população foi estratificada com base na concentração de Hg essa associação desapareceu, provavelmente mascarada pelas altas concentrações do metal. Entretanto quando foram estudados os haplótipos pode ser observada novamente a associação desses mesmos alelos com a diminuição da concentração do nitrito, confirmando os achados iniciais. O haplótipo mais frequente na população combina os alelos selvagens para todos os polimorfismos (T, 4b e G) e o haplótipo menos freqüente combina os alelos variantes. O haplótipo associado à menor concentração plasmática de nitrito combina os alelos selvagens (C, 4b e G), confirmando os primeiros resultados. Essa abordagem haplotípica é muito útil na observação de efeitos mais discretos uma vez que é possível observar os efeitos dos três polimorfismos agindo simultaneamente sobre uma variável, nesse caso o óxido nítrico. O presente estudo sugere que os fatores genéticos exercem grande influência sobre a produção e biodisponibilidade de NO e que esses fatores combinados com a exposição ambiental ao Hg podem agir de maneira sinérgica, aumentando a suscetibilidade aos efeitos cardiotóxicos do metal através da modulação da atividade da eNOS. / The mercury (Hg) exposure has been target of toxicological studies due the high potential of damage to human health. In the Amazon region the first studies reported the occupational exposure due the use in gold mining, however, recently become relevant the studies about the environment exposure due the fish intake in the riparian population. Several studies have been concentrated in the riparian community in the Tapajós river region, where the fish consumption is frequent and the methylmercury content in fish is responsible to exposure of this people. The MeHg presents toxic effects in the cardiovascular system and many researches groups try to elucidate the mechanisms that explain this effects. Some studies report a significant reducing in nitric oxide (NO) production after the Hg exposure, which could contribute to an altered physiology of the cardiovascular system, once the NO is a modulating factor of this system. The NO is produced by the endothelial nitric oxide synthase (eNOS) and its activity can be altered by many factors like polymorphisms in gene that codify this protein, among this: : T-786C in the promoter region, 27-pb VNTR in intron 4 and Glu298Asp in exon 7. In this regard, the present study mean to evaluate the effects of the eNOS polymorphisms over the NO synthesis among the Hg exposed subjects. In this work, the whole blood samples of 214 volunteers were analyzed for determination of Hg concentration, nitrite plasma concentration and genotyping. The age of the volunteers varied between 15 and 84 years old, including 103 men and 111 women. The blood mercury concentration varied between 1.7 and 179.3 µg/L and the nitrite plasma concentration varied between 85.7 and 695.8 M. Was determinate the systolic arterial pressure (SAP), diastolic arterial pressure (DAP), body mass index (BMI) and heart rate (HR). The SAP mean was 119.8 mmHg and the DAP mean was 71.8 mmHg. The BMI mean was 24.5 Kg/m2 and the HR mean was 70.4 beats per minute. There was no difference among the groups of the three polymorphisms according the volunteers characteristics: age, DAP, SAP, BMI, HR, blood Hg concentration and nitrite plasma concentration. When the polymorphisms were observed separately the reduced nitrite plasma concentration was associated with the presence of the alleles: C in promoter region, 4b in intron 4 and G in exon 7, however there is lack of association when the volunteers were grouped according the blood Hg concentration, probably due a mask effect of the high Hg concentration. When these three polymorphisms were observed simultaneously, in analysis of the haplotypes, the association between the same alleles and the nitrite plasma concentration was observed again, confirming the initial findings. The commonest haplotype in the volunteers combine the alleles of the three polymorphisms (T, 4b and G) and the less frequent haplotype combine the three variants alleles. There was an association between the haplotype C, 4b and G and reduced nitrite plasma concentration, according the result of the polymorphisms separately. The haplotype analysis is too interesting to observe discrete effects, once is possible to analyze the effects of the three polymorphisms acting simultaneously above one variable, in this case, nitric oxide production. The present study suggest that genetic factors could exert a relevant influence above the NO production and bioavailability and that this factors combined with environmental Hg exposure can acting synergic, increasing the susceptibility to Hg cardiovascular effects, through the modulation of the eNOS activity.

1 Univerzita Karlova v Praze 1. lékařská fakulta Některé aspekty patofyziologie plicní arteriální hypertenze a její výskyt v České republice Some aspects of pathophysiology of pulmonary arterial hypertension and its epidemiology in the Czech Republic MUDr. Pavel Jansa Praha 2011 2 Abstract Pulmonary arterial hypertension (PAH) is a group of diseases characterized by a progressive increase of resistance and pressure in pulmonary vascular bed. In all types of PAH the same four pathological processes are reported: vasoconstriction, inflammation, thrombosis and remodelling. The genetic background is essential for the development of PAH. We aimed to investigate the role of polymorphisms of endothelial nitric oxide synthase (eNOS) genes in PAH. We studied 142 PAH patients and 189 healthy subjects. We examined 3 polymorphisms of the eNOS gene, including the Glu298Asp polymorphism, 27-base pair (bp) variable numbers of tandem repeats (VNTR) and -786 T/C promoter gene polymorphism. Prevalence of 27-bp VNTR allele A was higher in patients with PAH compared with healthy controls. Patients with PAH associated with connective tissue diseases had higher prevalence of AA genotype compared with other PAH subgroups. The Glu298Asp polymorphism and -786 T/C polymorphism are not associated with PAH. Thrombotic arteriopathy is...