Numbers of cells and cell proliferation in intima of different human arteries

Increased cell proliferation in early atherosclerotic lesions is recognized as an essential event of atherogenesis but the levels of cell proliferation in different stages of atherosclerotic plague formation in different types of human large arteries are still insufficiently studied. In the present work, we studied intima thickness and proliferation of newly "infiltrates" hematogenous and resident cells in atherosclerotic lesions of the carotid and coronary arteries and compared these parameters with those in the aorta, reported by us in earlier publication. Analysis of intima thickness and proliferation in grossly unaffected intima and in different types pf atherosclerotic lesions (initial lesions, fatty streaks, lipofibrous, plaques, and fibrous plaque) revealed that although there were similar tendencies in the change of the infiltration levels of hematogenous cells and proliferation in different types of arteries, there were significant quantitative differences between different types of arteries. Hematogenous cells in lipofibrous plaques of the coronary and carotid arteries were found to account for a third and almost for a half of the total cell population, respectively, while atherosclerotic lesions in the aorta, as it has been shown by us earlier, to contain no more than 15% ofhematogenous cells. This suggests that the contribution of hematogenous cells to the development of atherosclerosis in the carotid and the coronary artery appears to be more significant than that in the aorta. Despite the differences in numbers of accumulating hematogenous cells in the intima, a similar "bell-shaped" dependence of cell numbers on the lesion type, involved in the following sequence: unaffected intima-initial lesions-fatty streaks-lipofibrous plaques-fibrous plaques, was detected in the coronary and carotid arteries. The visualization of proliferating cells (PCNA-positive) in atherosclerotic and unaffected zones of the coronary and carotid arteries revealed similar patterns. The maximum numbers of PCNA-positive resident cells were identified in lipofibrous plaques. The changes in the total cell numbers were accompanied by the changes in the numbers of both proliferating resident cells and proliferating hematogenous cells.     

Ultrasound evaluation of extracranial carotid artery lesions in Parkinsonian patients

The purpose of this investigation was to determine the atherosclerotic changes in patients with vascular parkinsonism and in patients with idiopathic Parkinson's disease, in order to evaluate the possible influence of the extracranial pathology of carotid arteries in developing lacunar cerebral infarcts. Degree of stenosis and plaque morphology of the extracranial part of carotids in both group of patients were evaluated by color Doppler flow imaging ultrasound investigation and the results were compared. We selected two matched groups of patients with parkinsonism: 22 patients with vascular parkinsonism, and 28 with idiopathic Parkinson's disease.The atherosclerotic changes found in patients with Parkinson's disease showed mild carotid lesions with mostly stable calcified plaques and lesser risk for embolic cerebral intravascular events contrary to the higher degree of carotid stenosis found in patients with vascular parkinsonism with mostly mixed plaques prone to embolization. Therefore, we suggest performing ultrasonographic examination of the extracranial part of carotid arteries in all patients with parkinsonism to assess risk of vascular accidents originating from carotid lesions. That would enable adequate treatment of parkinsonism and prevent further occurrence of intracranial vascular changes.     

The number of cells and the cell proliferation in intima of various human arteries

Increased cell proliferation at the early stages of an atherosclerotic lesion is considered an important stage of development of this pathology, but the degree of the proliferation at various stages of formation of atherosclerotic plaque in various human large arteries so far has been studied insufficiently. In the present work, we studied the thickness of intima and proliferation of the newly “infiltrated” hematogenic and resident cells in atherosclerotic lesion of carotid and coronary arteries; a comparison is also made with similar results obtained on the aorta and presented in our earlier publications. Analysis of thickness of intima and of proliferation in normal intima and at various stages of atherosclerotic lesion (initial stages, lipid strips, lipofibrous plaques, fibrous plaques) showed that, in spite of similar tendencies toward changing the level of infiltration of hematogenic cells and proliferation in various types of arteries, there exist significant quantitative differences between various types of arteries. Thus, it is found that hematogenic cells in lipofibrous plaques of coronary and carotid arteries account for one-third and almost half of the total cell population, respectively, whereas the atherosclerosis-lesioned sites of the aorta, as we showed earlier, contain no more than 15% of hematogenic cells. This allows one to think that the contribution of hemopoietic cells to development of atherosclerosis in carotid and coronary arteries is greater than in the aorta. In spite of differences in the number of the hemopoietic cells accumulating in intima, an analogous bell-shaped dependence of the number of cells on the type of lesion (in the sequence normal intima-initial stages of pathology-lipid strips-lipofibrous plaques-fibrous plaques) was shown for coronary and carotid arteries. Visualization of proliferating (PCNA-positive) cells in atherosclerosed and normal (unchanged) zones of coronary and carotid arteries revealed a similar picture. The maximum number of PCNA-positive resident cells was found in lipofibrous plaques. Changes of the total number of cells were accompanied by a change in the number of proliferating resident and proliferating hematogenic cells.     

Autocrine role of vascular IL-15 in intimal thickening

Interleukin 15 (IL-15) is a pro-inflammatory cytokine that modulates T cell recruitment and activation, independent of antigen. It has been detected in human atherosclerotic plaques and atherosclerotic plaques of apoE-/- mice. IL-15 regulates fractalkine (FKN)-CX3CR1 chemokine signaling which is involved in atherogenesis and promotes SMC proliferation. We investigated the role of IL-15 in intimal thickening after arterial injury. Treatment of serum-stimulated SMC with IL-15 in vitro attenuated proliferation and suppressed CX3CR1 and FKN mRNA expression. The role of endogenous IL-15 in vivo was investigated in injured carotid arteries of mice. Periadventitial arterial injury resulted in increased IL-15 expression in the media and neointima, paralleled by increased IL-15 receptor alpha expression. Blockade of endogenous IL-15 increased intimal thickening. FKN and CX3CR1 expression increased after injury and were further augmented after IL-15 blockade. These data suggest that endogenous IL-15 attenuated intimal thickening after arterial injury. The potential mechanism of action is suppression of CX3CR1 signaling.     

Atherosclerotic plaques occur in absence of intima-media thickening in both systemic sclerosis and systemic lupus erythematosus: a duplexsonography study of carotid and femoral arteries and follow-up for cardiovascular events

Introduction

The objective of this cross-sectional and retrospective cohort study was (1) to determine the usefulness of intima-media thickness (IMT) in contrast to plaque assessment, (2) to examine the value of additive femoral artery sonography and (3) to identify potential risk factors for atherosclerosis and incident cardiovascular events in systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) patients.

Methods

In this study, 90 SSc and 100 SLE patients were examined by duplexsonography. IMT was measured in common carotid and common femoral arteries, plaques were assessed in common, internal and external carotid and common, proximal superficial and deep femoral arteries. Different definitions of pathological IMT (pIMT) were compared with the presence of plaque. Results were evaluated in relation to traditional and non-traditional risk factors for baseline atherosclerosis (logistic regression) and their predictive value for cardiovascular events during follow-up (cox regression).

Results

Definite atherosclerosis occurred frequently without signs of subclinical atherosclerosis in both diseases: pIMT >0.9 mm was present in only 17/59 (28.9%) SSc and 13/49 (26.5%) SLE patients with already present atherosclerotic plaques. Using age-adjusted pIMT definitions, this rate was even lower (5.1-10.3% in SSc, 14.3-26.5% in SLE). Plaques were located only at the carotid or only at the femoral arteries in 26 (13.7%) and 24 (12.6%) patients, respectively. Age and nicotine pack-years were independently associated with atherosclerotic plaques in SLE and SSc patients, as well as the cumulative prednisolone dose in SSc subgroup, and ssDNA positive SLE patients had a lower risk for atherosclerotic plaque. During follow-up (available for 129/190 (67.9%) patients, 650 person-years), cardiovascular events occurred more often in patients with coronary heart disease (adjusted-hazards ratio (HR) 10.19, 95% confidence interval (CI) 3.04 to 34.17, P <0.001), male patients (adjusted-HR 8.78, 95% CI 2.73 to 28.19, P <0.001) and in patients with coexistent carotid and femoral plaques (adjusted-HR 5.92, 95% CI 1.55 to 22.67, P = 0.009). Patients with solely carotid or femoral plaque were not at higher risk.

Conclusion

Atherosclerotic plaque lesions can be found frequently in absence of intima-media thickening in both SSc and SLE patients. As well as routine sonography of carotid arteries, the sonography of femoral arteries is recommended to identify additional atherosclerotic lesions and to detect patients at a high risk for cardiovascular events.     

Spontaneous Aortic Lesions in Moose (Alces Alces L)

In 17 out of 22 aortas from moose, 6 months to more than 18 years, aortic lesions were found. Five different types of lesions were observed, fatty streaks were seen in 1, fibrous plaques in 7, fatty streaks with complicated lesions (calcification and acid mucopolysaccharides) in 3, fibrous plaques with complicated lesions in 2 and fibrous plaques with complicated lesions and fat droplets in 4 of the aortas. Elastic tissue degeneration of the inner two thirds of the tunica media was principally found in the aorta of the animals beyond 4 year of age. There was no statistical evidence for a correlation between age and frequency but a trend towards age dependence was seen. The percentage of involved surface was found to increase significantly (0.05 > P > 0.02) with age. There was no significant difference between affected male and female animals in the different age groups. The frequency of involved surface in different affected regions, comprising all age groups were, in the posterior abdominal portion, 13.0 %, in the anterior abdominal portion, 3.0 %, in the posterior thoracic portion 5.2 %, in the anterior thoracic portion, 0.1 % and in the aortic arch, 0.1 %. Proliferating endothelial cells and the source of smooth muscle cells were discussed.     

Imaging collagen in intact viable healthy and atherosclerotic arteries using fluorescently labeled CNA35 and two-photon laser scanning microscopy

We evaluated CNA35 as a collagen marker in healthy and atherosclerotic arteries of mice after both ex vivo and in vivo administration and as a molecular imaging agent for the detection of atherosclerosis. CNA35 conjugated with fluorescent Oregon Green 488 (CNA35/OG488) was administered ex vivo to mounted viable muscular (uterine), elastic (carotid), and atherosclerotic (carotid) arteries and fresh arterial rings. Two-photon microscopy was used for imaging. CNA35/OG488 labeling in healthy elastic arteries was compared with collagen type I, III, and IV antibody labeling in histologic sections. For in vivo labeling experiments, CNA35/OG488 was injected intravenously in C57BL6/J and apolipoprotein E(-/-) mice. Ex vivo CNA35/OG488 strongly labeled collagen in the tunica adventitia, media, and intima of muscular arteries. In healthy elastic arteries, tunica adventitia was strongly labeled, but labeling in tunica media and intima was prevented by endothelium and elastic laminae. Histology confirmed the affinity of CNA35 for type I, III, and IV collagen in arteries. Strong CNA35/OG488 labeling was found in atherosclerotic plaques. In vivo applied CNA35/OG488 minimally labeled the tunica intima of healthy carotid arteries. Atherosclerotic plaques in apolipoprotein E(-/-) mice exhibited large uptake. CNA35/OG488 imaging in organs revealed endothelium as a limiting barrier for in vivo uptake. CNA35/OG488 is a good molecular imaging agent for atherosclerosis.     

Multiphase hemodynamic simulation of pulsatile flow in a coronary artery

A multiphase transient non-Newtonian three-dimensional (3-D) computational fluid dynamics (CFD) simulation has been performed for pulsatile hemodynamics in an idealized curved section of a human coronary artery. We present the first prediction, to the authors' knowledge, of particulate buildup on the inside curvature using the multiphase theory of dense suspension hemodynamics. In this study, the particulates are red blood cells (RBCs). The location of RBC buildup on the inside curvature correlates with lower wall shear stress (WSS) relative to the outside curvature. These predictions provide insight into how blood-borne particulates interact with artery walls and hence, have relevance for understanding atherogenesis since clinical observations show that atherosclerotic plaques generally form on the inside curvatures of arteries. The buildup of RBCs on the inside curvature is driven by the secondary flow and higher residence times. The higher viscosity in the central portion of the curved vessel tends to block their flow, causing them to migrate preferentially through the boundary layer. The reason for this is the nearly neutrally buoyant nature of the dense two-phase hemodynamic flow. The two-phase non-Newtonian viscosity model predicts greater shear thinning than the single-phase non-Newtonian model. Consequently, the secondary flow induced in the curvature is weaker. The waveforms for computed hemodynamic parameters, such as hematocrit, WSS, and viscosity, follow the prescribed inlet velocity waveforms. The lower oscillatory WSS produced on the inside curvature has implications for understanding thickening of the intimal layer.     

Noninvasive detection of macrophages using a nanoparticulate contrast agent for computed tomography

Sudden fibrous cap disruption of 'high-risk' atherosclerotic plaques can trigger the formation of an occlusive thrombus in coronary arteries, causing acute coronary syndromes. High-risk atherosclerotic plaques are characterized by their specific cellular and biological content (in particular, a high density of macrophages), rather than by their impact on the vessel lumen. Early identification of high-risk plaques may be useful for preventing ischemic events. One major hurdle in detecting high-risk atherosclerotic plaques in coronary arteries is the lack of an imaging modality that allows for the identification of atherosclerotic plaque composition with high spatial and temporal resolutions. Here we show that macrophages in atherosclerotic plaques of rabbits can be detected with a clinical X-ray computed tomography (CT) scanner after the intravenous injection of a contrast agent formed of iodinated nanoparticles dispersed with surfactant. This contrast agent may become an important adjunct to the clinical evaluation of coronary arteries with CT.     

Is Cadmium Exposure Associated with the Burden,Vulnerability and Rupture of Human Atherosclerotic Plaques?

The general population is exposed to cadmium from food and smoking. Cadmium is a widely spread toxic pollutant that seems to be associated with cardiovascular diseases, although little is known if it contributes to the occurrence of atherosclerotic plaques and the process whereby plaques become vulnerable and are prone to rupture. We tested the hypotheses that cadmium exposure is associated not only with an increased subclinical burden of atherosclerotic plaques in different vascular territories and early signs of plaque vulnerability, but also with cadmium content and plaque-rupture in the clinical phase of the disease. Ultrasound technique was used to measure plaque prevalence and echogenicity in the carotid and femoral arteries in a population sample of women (n = 599) in whom blood cadmium was measured. In addition cadmium was measured in snap-frozen endarterectomies and whole blood obtained from patients who were referred to surgery because of symptomatic carotid plaques (n = 37). Sixteen endarterectomies were divided into three parts corresponding to different flow conditions and plaque vulnerability. In the population sample blood cadmium was associated with the number of vascular territories with plaques (p = 0.003 after adjustment for potential confounders). The cadmium concentrations in symptomatic plaques were 50-fold higher in plaque tissue than in blood. Cadmium levels in blood and plaque correlated, also after adjustment for smoking and other cardiovascular risk factors (p<0.001). Compared with the other parts of the plaque, the cadmium content was double as high in the part where plaque rupture usually occurs. In conclusion, the results show that cadmium exposure is associated with the burden of subclinical atherosclerosis in middle-aged women with different degrees of glucose tolerance, and that the content of cadmium in symptomatic plaques in patients is related to that in blood, but much higher, and preferentially located in the part of plaque where rupture often occurs.     

Spontaneous Aortic Lesions in Roe Deer (Capreolus Capreolus L)

In 34 out of 60 aortas from roe deer, aged from 6 months to more than 8 years, aortic lesions were found. The frequency of affected regions involved were, in the posterior abdominal portion 53.3 %, in the aortic arch 18.3 %, in the anterior abdominal portion 16.7 %, in the posterior thoracic portion 8.33 % and in the anterior thoracic portion 3.3 %. Of the observed lesions, fatty streaks were seen in 3, fatty streaks and fibrous plaques in 3, fatty streaks with complicated lesions (calcification and acid mucopolysaccharides) in 14 and fibrous plaques with complicated lesions in 14 of the aortas. Elastic tissue degeneration of the inner two thirds of the tunica media was principally found in the aorta of the animals beyond 4 years of age. The lesions significantly (P < 0.001) increased in number and severity with age and appeared to be more progressive in pregnant animals. There was, however, no significant difference between affected male and female animals in the different age groups.     

Histochemical evidence for inducible nitric oxide synthase in advanced but non-ruptured human atherosclerotic carotid arteries

In response to cytokine stimulation, the inducible isoform of the nitric oxide synthase (iNOS) produces large amounts of nitric oxide with potential consequences in the pathophysiology of atherosclerosis. Previous investigations have demonstrated the presence of iNOS in human atherosclerotic lesions. The goal of this study was to evaluate the occurrence of the expression of iNOS in ruptured versus non-ruptured human carotid atherosclerotic plaques. Using plastic-embedded sections, we performed in situ hybridization and immunohistochemistry on very advanced atherosclerotic lesions type V (non-ruptured) and type VI (ruptured) from 12 atheromatous carotid arteries from endarterectomy and six non-atherosclerotic internal mammary arteries from aorto-coronary bypass. Only one internal mammary artery expressed iNOS in the endothelium. In contrast, iNOS mRNA and protein were repeatedly expressed in advanced lesions type V in 5/7 cases, particularly in inflammatory regions. Specific cell markers identified iNOS-positive cells as macrophages and T-lymphocytes but also as smooth muscle cells and endothelial cells adjacent to these inflammatory regions. Nitration of protein tyrosines was not always associated to iNOS expression but more likely to the presence of inflammatory cells. In complicated lesions type VI, the occurrence of iNOS mRNA and protein expression diminished drastically (1/5 cases). Combined expression of iNOS mRNA and protein is frequently found in advanced but non-ruptured human atherosclerotic carotid lesions while it becomes rare after the plaque has ruptured. These findings suggest that iNOS could be an active participant in the plaque rupture event.     

Electrochemical impedance spectroscopy to characterize inflammatory atherosclerotic plaques

Despite advances in diagnosis and therapy, atherosclerotic cardiovascular disease remains the leading cause of morbidity and mortality in the Western world. Predicting metabolically active atherosclerotic lesions has remained an unmet clinical need. We hereby developed an electrochemical strategy to characterize the inflammatory states of high-risk atherosclerotic plaques. Using the concentric bipolar microelectrodes, we sought to demonstrate distinct Electrochemical Impedance Spectroscopic (EIS) measurements for unstable atherosclerotic plaques that harbored active lipids and inflammatory cells. Using equivalent circuits to simulate vessel impedance at the electrode–endoluminal tissue interface, we demonstrated specific electric elements to model working and counter electrode interfaces as well as the tissue impedance. Using explants of human coronary, carotid, and femoral arteries at various Stary stages of atherosclerotic lesions (n = 15), we performed endoluminal EIS measurements (n = 147) and validated with histology and immunohistochemistry. We computed the vascular tissue resistance using the equivalent circuit model and normalized the resistance to the lesion-free regions. Tissue resistance was significantly elevated in the oxLDL-rich thin-cap atheromas (1.57 ± 0.40, n = 14, p < 0.001) and fatty streaks (1.36 ± 0.28, n = 33, p < 0.001) as compared with lesion-free region (1.00 ± 0.18, n = 82) or oxLDL-absent fibrous atheromas (0.86 ± 0.30, n = 12). Tissue resistance was also elevated in the calcified core of fibrous atheroma (2.37 ± 0.60, n = 6, p < 0.001). Despite presence of fibrous structures, tissue resistance between ox-LDL-absent fibroatheroma and the lesion-free regions was statistically insignificant (0.86 ± 0.30, n = 12, p > 0.05). Hence, we demonstrate that the application of EIS strategy was sensitive to detect fibrous cap oxLDL-rich lesions and specific to distinguish oxLDL-absent fibroatheroma.     

Preliminary observations on the structure of the medio-intimal area of the rabbit coronary arteries. (A. Observations on 4-month-old rabbits)

The presence of the diffuse intimal thickening (DIT) is commonly considered the structural basis for the early atherosclerotic involvement of the coronary arteries. In the ambit of a systematic morphometric comparison of experimental atherosclerotic plaques of aorta and coronaries, we have studied the coronary medio-intimal junctions of 4 months old rabbits. Both at sub-epicardic and intra-myocardic coronary arteries level we have found fiber structures similar to DIT. These findings may help explaining why coronary atherosclerosis in rabbits does not represent, in the usual experimental models, a lesion particularly severe nor of precocious appearance.     

Atherosclerotic lesions of supra-aortic arteries in diabetic patients

The aim of this prospective study was to determine the prevalence and localization of stenotic atherosclerotic lesions of supra-aortic arteries in diabetic patients according to age and sex. Angiograms obtained by digital subtraction angiography were analyzed in 150 diabetic patients (study group) and 150 non-diabetic patients (control group) with symptoms of cerebral ischemia. Diabetic patients were found to have a significantly higher prevalence of stenotic atherosclerotic lesions of the internal carotid artery. Lesions of the large supra-aortic arteries were significantly more common in the left than in the right side of the neck (p < 0.001), but the difference between the diabetic and the non-diabetic group did not reach statistical significance. Hemodynamic conditions were found to be more important than diabetes for the occurrence of atherosclerotic lesions in these arteries. Changes in the proximal segment of the left common carotid artery were the most common finding in diabetic patients, hence attention should be paid to this localization on control examinations.     

Preliminary observations, at the ultrastructural level, on the reactivity of cerebral arteries from New Zealand rabbits to combined atherogenic stimuli (hypercholesterol diet and hypertension)

Both in monkeys (Rhesus and Cynomolgus) and in New Zealand rabbits fed an atherogenic diet, a marked delay in the appearance of atherosclerotic lesions of the cerebral arteries in comparison with other arterial districts has been observed. This appearance has been described in monkeys as relatively earlier if hypertension is added to the atherogenic diet. Preliminary observations on a little group of rabbits on a 3 months hypercholesterolic diet, subjected to Goldblatt aortic coarctation, have shown an increase of blood pressure and a severe gross atherosclerotic involvement of aorta, resembling the one obtainable after 6 months of atherogenic diet. Histologically, the aorta predominantly shows lesions of the fatty streaks type with necrotic areas in the deep; the carotid lesions show some lipid in smooth muscle cells disseminated in a sub-endothelial "edematous" space (rich in protein). The cerebral arteries do not show any lesion. At TEM, the aortic lesions look sometimes as advanced plaques with an initial fibrosis at the surface; the carotid lesions are characterized by a granular deposit in the sub-endothelial space in which some smooth muscle cells (with lipid in the cytoplasm) are present; in the cerebral arteries only the presence of collagen fibers among the smooth muscle cells of the media, never observed in the animals fed the atherogenic diet alone, has sometimes been noted.     

Experimental determination of circumferential properties of fresh carotid artery plaques

Carotid endarterectomy (CEA) is currently accepted as the gold standard for interventional revascularisation of diseased arteries belonging to the carotid bifurcation. Despite the proven efficacy of CEA, great interest has been generated in carotid angioplasty and stenting (CAS) as an alternative to open surgical therapy. CAS is less invasive compared with CEA, and has the potential to successfully treat lesions close to the aortic arch or distal internal carotid artery (ICA). Following promising results from two recent trials (CREST; Carotid revascularisation endarterectomy versus stenting trial, and ICSS; International carotid stenting study) it is envisaged that there will be a greater uptake in carotid stenting, especially amongst the group who do not qualify for open surgical repair, thus creating pressure to develop computational models that describe a multitude of plaque models in the carotid arteries and their reaction to the deployment of such interventional devices. Pertinent analyses will require fresh human atherosclerotic plaque material characteristics for different disease types. This study analysed atherosclerotic plaque characteristics from 18 patients tested on site, post-surgical revascularisation through endarterectomy, with 4 tissue samples being excluded from tensile testing based on large width-length ratios. According to their mechanical behaviour, atherosclerotic plaques were separated into 3 grades of stiffness. Individual and group material coefficients were then generated analytically using the Yeoh strain energy function. The ultimate tensile strength (UTS) of each sample was also recorded, showing large variation across the 14 atherosclerotic samples tested. Experimental Green strains at rupture varied from 0.299 to 0.588 and the Cauchy stress observed in the experiments was between 0.131 and 0.779 MPa. It is expected that this data may be used in future design optimisation of next generation interventional medical devices for the treatment and revascularisation of diseased arteries of the carotid bifurcation.     

Spontaneous Aortic Lesions in Fallow Deer (Dama Dama L)

In 19 out of 22 aortas from fallow deer, 15 months to 5½ years, aortic lesions were found. Three types of lesions were observed, fatty streaks were seen in 2, fibrous plaques in 15 and fibrous plaques with complicated lesions (calcification and acid mucopolysaccharides) in 2 of the aortas. Elastic tissue degeneration of the inner two thirds of the tunica media was frequently found in the aorta of the animals > 3½–5½ years of age. There was no statistical evidence for a correlation between age and frequency (P ~ 0.10) but a trend towards age dependence was seen. The percentage of involved surface was found to significantly increase (0.05 > P > 0.01) with age. Lesions were found to start in the abdominal aorta in young animals and to extend cranially to the thoracic aorta with age. The percentage of involved surface in different affected regions, comprising all age groups were, in the posterior abdominal portion, 10.5 %, in the anterior abdominal portion, 4.3 % and in the posterior thoracic portion, 1.04 %. The influence of hemodynamic flow upon the localization of the aortic lesions, the endothelial cell population density and the endothelial nuclear patterns were discussed.