BACKGROUND: It is well established that thoracic aortic aneurysms (TAA) and abdominal aortic aneurysms (AAA) have different risk factors, clinical features, and genetic influences. Differences between and amongst subtypes of TAAs have received less attention. Despite observations of divergent clinical outcomes between ascending thoracic aortic aneurysms (ATAAs) and descending thoracic aortic aneurysms (DTAAs), etiologic factors determining the anatomic distribution of these aneurysms are not well understood. METHODS: From 3,247 patients registered in an institutional Thoracic Aortic Center Database from July 1992 through August 2013, we identified 921 patients with full aortic dimensional imaging by CT or MRI scan with TAA > 3.5 cm and without evidence of aortic dissection (AoD). Patients were analyzed in three groups: isolated ATAA (n=677), isolated DTAA (n=97), and combined ATAA and DTAA (n=146). RESULTS: Patients with a DTAA, alone or with coexistent ATAA, had significantly more hypertension (80.6% vs. 61.8%, p<.001) and a higher burden of atherosclerotic disease ( 86.7% vs. 7.5%, p<.001) ) and were more likely to be female (59.3% vs. 29.5%, P<.001). Conversely, patients with isolated ATAA were significantly younger (average age 59.5 vs. 71, p<.001), and contained almost every case of overt genetically-triggered TAA. Patients with isolated DTAA were demographically indistinguishable from patients with combined ATAA and DTAA. In follow up, patients with isolated DTAA, or with ATAA and DTAA, experienced significantly more aortic events (aortic dissection/rupture) and had higher mortality than patients with isolated ATAA. CONCLUSIONS: Based on patient characteristics and outcomes, subtypes of TAA emerge. DTAA with or without associated ATAA or AAA appears to be a disease more highly associated with atherosclerosis, hypertension, and advanced age. In contrast, isolated ATAA appears to be a clinically distinct entity with a higher burden of genetically triggered disease. These data have important implications for familial screening recommendations for TAA.

Actin isoform specific mutations have been identified as causes for various human diseases. These include twelve missense mutations in γ-nonmuscle actin leading to early onset autosomal dominate nonsyndromic hearing loss and twenty two missense mutations in α-smooth muscle actin leading to thoracic aortic aneurysms and dissections (TAAD). The molecular mechanisms leading to these human pathologies are mainly unknown, principally due to the inability to isolate pure mutant γ-nonmuscle actin and α-smooth muscle actin in quantities required for biochemical analysis. To begin to address these problems, I have individually expressed the human nonmuscle actin isoforms, β– and γ– nonmuscle actin, in a baculovirus expression system and characterized their biochemical properties. Surprisingly, despite a conserved amino acid difference of only 4 residues at or near the N-terminus, Ca-γ-actin exhibits slower monomeric and filamentous biochemical properties than β-actin. In the Mg-form, the difference between the two is smaller. Mixing experiments with Ca-actins reveal the two will readily co-polymerize. Calcium bound in the high affinity binding site of γ-actin may cause a selective energy barrier relative to β-actin that retards the equilibration between G– and F-monomer conformations resulting in a slower polymerizing actin with greater filament stability. This difference may be particularly important in sites such as the γ-actin-rich cochlear hair cell stereocilium where local mM calcium concentrations may exist. In hair cells γ-nonmuscle actin seems to play a central role in stereocilia maintenance. To determine how the deafness causing D51N-γ-mutant actin mutation leads to deafness, I expressed and characterized it in the γ-actin background. The D51N mutation, lethal when cloned into yeast, displayed decreased filament stability and polymerization kinetics of an actin more dynamic than γ-actin. This result suggests that the hearing effects of the γ-actin mutations on the hearing apparatus are not simply caused by an inability to polymerize. The observed increased polymerization rates and decreased filament stability may have major implications for the human disease, as the mutation may alter the ability of the γ-actin to fulfill its maintenance functions. To address the basis by which TAAD mutations cause vascular dysfunction I introduced two of the know human mutations, N115T and R116Q, into yeast actin, 86% identical to human α-smooth muscle actin. I then generated yeast strains expressing each of these mutations as the sole actin in the cell to assess their effect on actin function in vivo and in vitro. Both mutant strains exhibited reduced ability to grow under a variety of stress conditions, although the N115T cells were more severely affected. In vitro the mutations caused exhibited altered thermostability and nucleotide exchange rates indicating effects on monomer conformation with R116Q the most severely affected. The N115T actin demonstrated a biphasic elongation phase during polymerization, while R116Q actin demonstrated a markedly extended nucleation phase. Allele-specific effects were also seen on critical concentration, rate of depolymerization and filament treadmilling. R116Q filaments were hypersensitive to severing by the actin-binding protein cofilin. In contrast, N115T filaments were hyposensitive to cofilin, despite near normal binding affinities of actin for cofilin. The mutant specific effects on actin behavior suggest that individual mechanisms may contribute to TAAD. Understanding the mechanisms of actin dependent human diseases requires elucidation of the effects of the mutations on the behavior of actin per se, its regulation, and the impact on actin mediated processes within the cell. The work provided in this thesis and future studies will provide the information required to understand the pathways involved in these diseases and form innovative treatments for deafness and TAAD.

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 5 uppsatser.

No description available.

No description available.

No description available.

<p><i>Chlamydophila pneumoniae</i> (<i>C. pneumoniae</i>) has been suggested as a stimulator of chronic inflammation in atherosclerosis. <i>C. pneumoniae</i> DNA was demonstrated in aortic biopsies in 50% of patients with stable angina pectoris or acute coronary syndrome undergoing coronary artery bypass grafting. <i>C. pneumoniae</i> mRNA, a marker of replicating bacteria, was demonstrated in 18% of the aortic biopsies. </p><p>Inflammation may have a role in the pathogenesis of thoracic aortic aneurysm, aortic dissection and aortic valve stenosis. <i>C. pneumoniae </i>DNA was demonstrated in aortic biopsies in 26% of thoracic aortic aneurysm patients and in 11% of aortic dissection patients undergoing thoracic surgery and in 22% of stenotic aortic heart valves from patients undergoing aortic valve replacement. No bacterial mRNA was demonstrated in these aortic biopsies, nor in the valves, suggesting that the infection has passed into a persistent state. <i>C. pneumoniae</i> DNA was demonstrated in peripheral blood mononuclear cells in only 5% of aortic valve stenosis patients and not in thoracic aortic aneurysm or aortic dissection patients, suggesting that the bacterium disseminated to the cardiovascular tissue long before the patient required surgery. The copper/zinc ratio in serum, a marker of infection/inflammation, was significantly elevated in thoracic aortic aneurysm patients, supporting an inflammatory pathogenesis. Patients positive for <i>C. pneumoniae</i> in the aortic valve had more advanced coronary atherosclerosis, further supporting a possible role for <i>C. pneumoniae</i> in atherosclerosis. </p><p>Mice were infected with <i>C. pneumoniae</i> that disseminated to all organs investigated (i.e. lungs, heart, aorta, liver and spleen). Trace element concentrations were altered in infected animals with an increased copper/zinc ratio in serum, a progressively increased iron concentration in the liver and a progressively decreased iron concentration in serum. Iron is important for <i>C. pneumoniae</i> metabolism, and a changed iron homeostasis was noted in infected mice by alterations in iron-regulating proteins, such as DMT1 and hepcidin.</p>

Chlamydophila pneumoniae (C. pneumoniae) has been suggested as a stimulator of chronic inflammation in atherosclerosis. C. pneumoniae DNA was demonstrated in aortic biopsies in 50% of patients with stable angina pectoris or acute coronary syndrome undergoing coronary artery bypass grafting. C. pneumoniae mRNA, a marker of replicating bacteria, was demonstrated in 18% of the aortic biopsies. Inflammation may have a role in the pathogenesis of thoracic aortic aneurysm, aortic dissection and aortic valve stenosis. C. pneumoniae DNA was demonstrated in aortic biopsies in 26% of thoracic aortic aneurysm patients and in 11% of aortic dissection patients undergoing thoracic surgery and in 22% of stenotic aortic heart valves from patients undergoing aortic valve replacement. No bacterial mRNA was demonstrated in these aortic biopsies, nor in the valves, suggesting that the infection has passed into a persistent state. C. pneumoniae DNA was demonstrated in peripheral blood mononuclear cells in only 5% of aortic valve stenosis patients and not in thoracic aortic aneurysm or aortic dissection patients, suggesting that the bacterium disseminated to the cardiovascular tissue long before the patient required surgery. The copper/zinc ratio in serum, a marker of infection/inflammation, was significantly elevated in thoracic aortic aneurysm patients, supporting an inflammatory pathogenesis. Patients positive for C. pneumoniae in the aortic valve had more advanced coronary atherosclerosis, further supporting a possible role for C. pneumoniae in atherosclerosis. Mice were infected with C. pneumoniae that disseminated to all organs investigated (i.e. lungs, heart, aorta, liver and spleen). Trace element concentrations were altered in infected animals with an increased copper/zinc ratio in serum, a progressively increased iron concentration in the liver and a progressively decreased iron concentration in serum. Iron is important for C. pneumoniae metabolism, and a changed iron homeostasis was noted in infected mice by alterations in iron-regulating proteins, such as DMT1 and hepcidin.

Este estudo avaliou a função vascular em anéis de aorta e no leito vascular mesentérico (LVM) de camundongos com deleção dos receptores <font face=\"symbol\">a2A e <font face=\"symbol\">a2Cadrenérgicos (KO) com 3, 5 e 7 meses, os quais apresentam uma hiperatividade simpática acompanhada de cardiomiopatia. Os KO apresentaram um aumento da freqüência cardíaca em todos os grupos avaliados, e hipertrofia ventricular esquerda aos 5 e 7 meses. Na aorta, o relaxamento dependente (acetilcolina) e independente (nitroprussiato de sódio) do endotélio e da via font face=\"symbol\">a-adrenérgica (isoproterenol), assim como a contração (fenilefrina e serotonina) e a mobilização de Ca2+ não foram alterados nos KO aos 3, 5 e 7 meses. Nos KO aos 3 meses, o relaxamento mediado pelos receptores ?2-adrenérgicos (clonidina) foi reduzido. Tanto a contração (noradrenalina) como o relaxamento (acetilcolina) no LVM dos KO aos 7 meses não foi alterado. Assim, sugere-se que os vasos arteriais parecem ser menos sensíveis do que o coração aos efeitos crônicos da hiperatividade simpática nos camundongos com deleção dos receptores <font face=\"symbol\">a2A e <font face=\"symbol\">a2C adrenérgicos. / This study assed the vascular function in aortic rings and in mesenteric vascular bed (MVB) from mice with disruption of <font face=\"symbol\">a2A and <font face=\"symbol\">a2Cadrenoceptors (KO) with 3, 5 and 7 months of age, that present sympathetic hyperactivity associated with cardiomyopathy. Heart rate was increased in all KO groups, and left ventricular hypertrophy was observed only in 5 and 7 month-old KO. There are no changes in the relaxation induced by acetylcholine (ACh), sodium nitroprusside and isoproterenol in aortic rings from all groups. In addition, the contraction induced by phenylephrine and serotonin, and Ca2+ handling did not change. However, in aorta from 3 month-old KO the relaxation induced by clonidine (<font face=\"symbol\">a2-adrenergic agonist) was reduced. In MVB from 7 month-old KO, neither the contraction (noradrenaline) nor relaxation (ACh) was modified. The results suggest that arterial vessel has been more resistant than heart to chronic effects induced by sympathetic hyperactivity observed in mice with disruption o<font face=\"symbol\">a2A and <font face=\"symbol\">a2C-adrenoceptors.

Este estudo avaliou a função vascular em anéis de aorta e no leito vascular mesentérico (LVM) de camundongos com deleção dos receptores <font face=\"symbol\">a2A e <font face=\"symbol\">a2Cadrenérgicos (KO) com 3, 5 e 7 meses, os quais apresentam uma hiperatividade simpática acompanhada de cardiomiopatia. Os KO apresentaram um aumento da freqüência cardíaca em todos os grupos avaliados, e hipertrofia ventricular esquerda aos 5 e 7 meses. Na aorta, o relaxamento dependente (acetilcolina) e independente (nitroprussiato de sódio) do endotélio e da via font face=\"symbol\">a-adrenérgica (isoproterenol), assim como a contração (fenilefrina e serotonina) e a mobilização de Ca2+ não foram alterados nos KO aos 3, 5 e 7 meses. Nos KO aos 3 meses, o relaxamento mediado pelos receptores ?2-adrenérgicos (clonidina) foi reduzido. Tanto a contração (noradrenalina) como o relaxamento (acetilcolina) no LVM dos KO aos 7 meses não foi alterado. Assim, sugere-se que os vasos arteriais parecem ser menos sensíveis do que o coração aos efeitos crônicos da hiperatividade simpática nos camundongos com deleção dos receptores <font face=\"symbol\">a2A e <font face=\"symbol\">a2C adrenérgicos. / This study assed the vascular function in aortic rings and in mesenteric vascular bed (MVB) from mice with disruption of <font face=\"symbol\">a2A and <font face=\"symbol\">a2Cadrenoceptors (KO) with 3, 5 and 7 months of age, that present sympathetic hyperactivity associated with cardiomyopathy. Heart rate was increased in all KO groups, and left ventricular hypertrophy was observed only in 5 and 7 month-old KO. There are no changes in the relaxation induced by acetylcholine (ACh), sodium nitroprusside and isoproterenol in aortic rings from all groups. In addition, the contraction induced by phenylephrine and serotonin, and Ca2+ handling did not change. However, in aorta from 3 month-old KO the relaxation induced by clonidine (<font face=\"symbol\">a2-adrenergic agonist) was reduced. In MVB from 7 month-old KO, neither the contraction (noradrenaline) nor relaxation (ACh) was modified. The results suggest that arterial vessel has been more resistant than heart to chronic effects induced by sympathetic hyperactivity observed in mice with disruption o<font face=\"symbol\">a2A and <font face=\"symbol\">a2C-adrenoceptors.