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PubMed1995

Complex structure of the common carotid artery of sheep.

BACKGROUND: Mechanical properties of blood vessels are dictated by the vessel wall structure. In many large conduit vessels the tunica media is a sheath of circular musculature and the tunica adventitia a layer of fibrous connective tissue with limited longitudinal extensibility. In contrast, the carotid artery of the sheep displays in each tunica a more complex architecture of muscle and connective tissue. METHODS: Vessels collected from ewes were measured and processed for light microscopy and for transmission electron microscopy. RESULTS: Layers of histologically different materials are found within the tunica intima, media and adventitia. (1) The tunica media is made of circumferentially arranged muscle cells markedly different at different depths. In the innermost third of the media, muscle cells are small and with irregular profiles, the cells are widely separated, and the extracellular material is abundant and composed mainly of elastic fibres. In the outermost third, muscle cells are larger and with more regular profiles, the cells are relatively close to each other and the extracellular material is sparse and consists mainly of collagen fibrils. (2) A small number of fibroblasts is found in all parts of the media amongst the preponderant muscle cells. (3) The intima contains fibroblast-like cells and longitudinally arranged muscle cells. (4) The adventitia contains a thick layer of collagen and elastic fibres; external to this, it displays a conspicuous musculature, made of large bundles of longitudinal muscle. CONCLUSIONS: The carotid artery of the sheep presents in all three coats of its wall features which are at variance from those in the better known vessels of small laboratory animals. The presence of many layers of material within the wall, the heterogeneity of the tissues found, and the occurrence of an extensive longitudinal musculature, have important effects on the mechanical properties of the vessel.

Animals↗
PubMed1987

Evaluation of long-term patency rates of different techniques of arterial anastomosis in rabbits.

The results of 160 arterial anastomoses performed with four different techniques are presented. The popliteal arteries (mean diameter 0.7 mm) of 40 rabbits in each of four groups were anastomosed using: I. End-to-end technique with assymetrical sleeving of the adventitia; II. end-to-end technique with symetrical sleeving of the adventitia and wrapping of the suture site with a collagen cuff; III. end-to-end technique with symetrical trimming of the adventitia; and IV. end-in-end technique. Long-term patency rates for the above techniques were as follows: Group I, 92.5%; Group II, 87.5%; Group III, 92.5%; Group IV, 90.0%. Group IV anastomoses were completed in an average of 15 minutes compared with an overall average of 24 minutes for the other three groups.

Animals↗
PubMed1996

Uncoupling in the wall of the cartilaginous bronchus of the pig produced by smooth muscle contraction.

Studies in small non-cartilaginous airways suggest that the cross sectional area of the airway wall (comprising the smooth muscle and mucosa) is unaltered during the contraction-relaxation cycle produced by bronchial provocation. In the present study we examined whether the wall area of large cartilaginous bronchi remained constant during bronchoconstriction produced by acetylcholine (ACh, 10(-4)-10(-2)M), and if not the effect of this on the narrowing of the bronchial lumen. Narrowing of the lumen and adventitia of bronchial segments, 3.6 mm id from pigs, was simultaneously recorded using endoscopy and video imaging of the airway lumen. Concurrently, the shortening of the smooth muscle was estimated morphometrically from the same bronchi fixed during muscle contraction. In individual bronchi, ACh produced from 5 to 60% shortening of the smooth muscle, which caused up to 64% narrowing of the bronchial lumen, but only approximately 10% narrowing of the adventitia. Lumen narrowing was greater than predicted. Morphological assessment showed a doubling of the area between the smooth muscle and the cartilage, in response to maximum smooth muscle contraction by ACh. In contrast the area of the smooth muscle and mucosa did not change. Similar changes in bronchial morphology were produced in whole lung slices, incubated in ACh or histamine. We conclude that the inner airway wall uncouples from the outer wall during muscle contraction and that this increases the narrowing of the airway lumen relative to the adventitia.

Acetylcholine↗
PubMed1980

An electron microscopic study of the baroreceptors in the internal carotid artery of the spontaneously hypertensive rat.

The carotid baroreceptor field of normotensive (NTR) and spontaneously hypertensive rats (SHR) examined in this study extends for about 0.5 mm along the length and about 1/3 to 1/2 of the circumference of the wall of the internal carotid artery opposite to the carotid body. The vascular wall of the baroreceptor field exhibits neither a marked dilation to form a carotid sinus nor histological differences in the intima and media compared to other parts of the carotid artery. Histologically the adventitia of the baroreceptor field is characterized by (1) an increased thickness and by less well developed elastic lamellae in comparison with other parts of the arterial wall, (2) a profuse blood and nerve supply, and (3) a richness of cellular elements. The presumptive baroreceptor terminals are localized in the inner 1/3 of the adventitia and display local enlargements that appear to show preferential association with the cell body or processes of the Schwann cell but not with other components of the adventitia. the enlargements are characterized by an accumulation of very densely packed mitochondria, and glycogen particles. No morphological alterations were noted in the baroreceptor terminals of SHR except for proliferated basal laminae that invest the terminals. Our work does not support the concept that resetting of the baroreceptors is due to degeneration of the terminals.

Animals↗
PubMed1983

The role of neuronal and extraneuronal uptake in the inactivation of 3H-(--)noradrenaline in the rabbit aorta determined by a method relating with amine diffusion in the tissue.

Apparent coefficients of diffusion for 3H-noradrenaline and 14C-sorbitol were determined in the different layers of the rabbit aorta; uptake1 and uptake2 were inhibited. For 3H-noradrenaline, a value of 6.3 . 10(-7) cm2 . s-1 was obtained in intact aorta and a similar one in intima-media, while that in adventitia was three times higher than in intact aorta. The apparent coefficient was the same for 3H-noradrenaline and 14C-sorbitol in adventitia. However, the values were slightly higher for 3H-noradrenaline than for 14C-sorbitol in intact aorta and in intima-media. Thus, the distribution of sorbitol did not exactly reflect the distribution of noradrenaline in these two preparations, even when both uptake mechanisms were inhibited. When either uptake1 or uptake2 was intact, about 60% of the 3H-noradrenaline (0.12 mumol . 1(-1) was inactivated on its way through the vessel wall (intact aorta). This indicated that each mechanism was equieffective in removing noradrenaline from the extracellular fluid either in the adventitia (uptake1) or intima-media (uptake2). Similarly, when noradrenaline left the extracellular space by diffusion, about the same amount of noradrenaline was inactivated neuronally and extraneuronally. However, under classical incubation conditions, neuronal inactivation of 3H-noradrenaline was three to five times higher than extraneuronal one. This difference reflected the rapid access of noradrenaline to the neurones rather than the capacity of the neuronal and extraneuronal uptake sites to remove the amine from the extracellular fluid in the different layers of the aortic wall.

Animals↗
PubMed1989

Immunolocalization of collagen types I and III in the arterial wall of the rat.

Collagen types I and III were located by immunofluorescence procedures in the aorta and coronary arteries of the rat. Type I collagen was most prevalent in the adventitia of the aorta with only small amounts present in the intima and media. Type III collagen appeared to be a significant component in the media of the aorta and also in the adventitia of both blood vessels. The intima and media of the coronary arteries did not stain strongly for either type I or III collagen. Neither staining procedure was altered with preincubation of the sections with hyaluronidase or chondroitinase ABC. These studies indicate that type III collagen is a major component of the adventitia which has previously not been recognized by immunohistochemical techniques, possibly due to masking of collagen staining with glycosaminoglycans.

Animals↗
PubMed1989

Early carcinoma of the extrahepatic bile duct.

This study attempts to define early carcinoma of the extrahepatic bile duct through a study of 11 patients whose carcinomatous invasion did not extend to the outer layer of the bile duct. The patients were divided into the following 3 groups, namely; a mucosa group comprised of 3 patients, a fibromuscular layer group comprised of 5 patients, and an adventitia group comprised of 3 patients. None of the patients had any lymphnode metastases. Histological characteristics were determined according to infiltrative growth (INF alpha, beta, gamma), lymphatic invasion (ly), venous invasion (v) and perineural invasion (pn). In the mucosa group, INF alpha was observed in 2 patients, while ly, v, and pn factors were all negative. In the fibromuscular layer group, INF beta was seen in 3 patients, ly was positive in 2 patients, while v, and pn factors were negative in all patients. In the adventitia group, INF gamma was found in 2 patients, and ly, v, and pn factors were positive in all patients except for 1 in whom v was negative. Death from recurrence occurred in all the adventitia group patients and in 1 other patient. Early carcinoma of the extrahepatic bile duct could therefore be defined at present, as being carcinoma confined to within the mucosa and fibromuscular layer.

Adenocarcinoma↗
PubMed1999

Study of gene delivery in a rabbit vein graft model. Improvement of the efficiency of gene transfer into vein grafts.

Gene therapy is a therapeutic strategy in treating cardiovascular disease. Vein graft failure, the major limitation on coronary artery bypass surgery, may be amenable to gene approaches. Some studies describe gene therapies using functioning genes to prevent vein graft stenosis. Gene transfer efficiency remains a major issue. In this rabbit vein graft model, we studied gene delivery using a replication-deficit recombinant adenovirus to improve gene transfer efficiency into vein grafts. The adenovirus vector that contains the E.coli lacZ gene encoding beta gal was used because this vector is widely used and thought to be effective. Gene transfer was detected by X-gal staining. We hypothesized that dimethylsulfoxide and hyaluronidase, both drug delivery enhancers, would improve efficiency and that, in transfer to adventitia, direct injection would be more effective than dwelling. We studied 3 gene delivery methods to intima and media (controls, using dimethylsulfoxide and using hyaluronidase before transfection) and 2 delivery methods to adventitia (direct injection and dwelling). We used 6 rabbits per delivery method. X-gal stained positive cell rates were counted using light microscopy. Our findings indicate that (1) dimethylsulfoxide increased the efficiency of transfection to media and intima, (2) hyaluronidase increased intimal transfection efficiency, (3) direct injection to adventitia was more effective than dwelling. These findings suggest that in vein grafting, our methods are feasible for improving gene transfer efficiency.

Adenoviridae↗
PubMed1997

The angiopathy of subcortical arteriosclerotic encephalopathy (Binswanger's disease): immunohistochemical studies using markers for components of extracellular matrix, smooth muscle actin and endothelial cells.

A pronounced obliterative microangiopathy of the deep cerebral white matter is one of the cardinal features in classical cases of Binswanger's encephalopathy. We have characterised the alterations taking place in the intima, media and adventitia of obliterated arterial vessels in seven autopsy cases of this encephalopathy. The adventitia of fibrosed vessels showed immunoreactive material indicating a marked deposition of normally occurring collagen types, i.e. I, III and V. Similar deposits occurred in degenerated parts of the media. Two of the cases had, in addition, signs of collagen type VI-immunoreactive material in the adventitia and media. The elastica of arteries was often split and formed multiple layers. The inner part of the blood vessel walls contained immunoreactivity to collagen type IV and laminin, indicating increased amounts of basal lamina components. Using actin immunostaining the fibrosed arterial vessels showed a severe reduction of smooth muscle cells of the media. However, many terminal arterioles presented a marked actin immunostaining, possibly indicating hypertrophy of smooth muscle cells. The endothelial cell layer did not show any changes with regard to expression of glucose transporter 1, factor VIII, Ulex europaeus agglutinin I and CD34. Degeneration of the media associated with depositions of collagens type I, III, IV, V and possibly type VI, as well as other components of extracellular matrix, will jeopardize the regulatory functions of the afflicted vessels. The maintenance of the endothelial lining of the obliterated vessels probably counteracts thrombosis in the vessels.

Adult↗
PubMed1993

Histopathologic correlation of the three-layered intravascular ultrasound appearance of normal adult human muscular arteries.

The purpose of this study was to correlate intravascular ultrasound images from normal peripheral muscular arteries with the microscopic arterial components by using surgical microdissection techniques. There has been uncertainty about the precise anatomic constituents that are represented by the intravascular ultrasound three-layer image in human peripheral arteries. Forty of 66 grossly normal human femoropopliteal arterial segments obtained at autopsy were found to have a three-layered appearance and were subjected to selective surgical microdissection of intima, media, or adventitia. After microdissection, arteries were imaged with a 30 MHz intravascular ultrasound system; two observers blindly reviewed video tapes to assess for the presence or absence of a one-, two-, or three-layered arterial appearance. Removal of internal elastic lamina and/or intima results in a weak but evident inner ultrasound acoustic interface as a result of the media, which is normally echo-lucent. Removal of the adventitia and/or external elastic lamina results in a weak outer ultrasound acoustic interface. Isolated removal of the media does not alter the three-layered ultrasound image. In normal adult human femoropopliteal arteries the inner bright acoustic reflection (layer) is derived from the interface of blood with the intima and internal elastic lamina and the second bright interface (third layer) is from the external elastic lamina and adventitia. The mid-echo-lucent zone is the result of the media. However, any portion of the arterial wall, including muscular media, can act as an acoustic interface.

Adult↗
PubMed1975

Cyclic 3',5'-AMP phosphodiesterase of rabbit aorta.

Cyclic AMP and cyclic GMP phosphodiesterase activities (3' : 5'-cyclic AMP 5'-nucleotidohydrolase, EC 3.1.4.17) were demonstrated in the isolated intima, media, and adventitia of rabbit aorta. The activity for cyclic AMP hydrolysis in the intima was 2.7-fold higher than that for cyclic GMP hydrolysis. The activity for cyclic AMP hydrolysis in the media was approximately equal to that for cyclic GMP hydrolysis, but in the adventitia, cyclic GMP hydrolytic activity was 2.1-fold higher than cyclic AMP hydrolytic activity. Distribution of the activator of the phosphodiesterase was studied in the three layers. Each layer contained the activator. The activator was predominantly localized in the smooth muscle layer (the media). The effect of the activator and Ca2+ on the media cyclic AMP and cyclic GMP phosphodiesterase was also briefly studied. The activity of the cyclic GMP phosphodiesterase was stimulated by micromolar concentration of Ca2+ in the presence of the activator. However, the activity of the cyclic AMP phosphodiesterase was not significantly stimulated by Ca2+ up to 100 muM in the presence of the activator. Above 90% of cyclic nucleotide phosphodiesterase activity in the whole aorta was found to be derived from the media. A major portion (60-70%) of the media enzyme was found in 105 000 times g supernatant. Cyclic AMP phosphodiesterase in the supernatant was partially purified through Sepharose 6B column chromatography and partially separated from cyclic GMP phosphodiesterase. Using a partially purified preparation from the 105 000 times g supernatant the main kinetic parameters were specified as follows: 1) The pH optimum was found to be about 9.0 using Tris-maleate buffer. The maximum stimulation of the enzyme by Mg2+ was achieved at 4mM of MgC12. 2) High concentration of cyclic GMP (0.1 mM) inhibited noncompetitively the enzyme activity, and the activity was not stimulated at any tested concentration of cyclic GMP. 3) Activity-substrate concentration relationship revealed a high affinity (Km equals 1.0 muM) and low affinity (Km equals 45 muM) for cyclic AMP. The homogenate and 105 000 times g supernatant of the media also showed non-linear kinetics similar to the Sepharose 6B preparation and their apparent Km values for cyclic AMP hydrolysis were 1.2 muM and 36-40 muM and an enzyme extracted by sonication from 105 000 times g precipitate also exhibited non-linear kinetics (Km equals 5.1 muM and 70 muM). 4) Papaverine exhibited much stronger inhibition on the aorta cyclic AMP phosphodiesterase (50% inhibition of the intima enzyme, I5 o at 0.62 muM, I5 o of the media at 0.62 muM and I5 o of the adventitia at 1.0 muM) than on the brain (I5 o at 8.5 muM) and serum (I5 o at 20 muM) cyclic AMP phosphodiesterase, while theophylline inhibited these enzymes similarly. However, cyclic GMP phosphodiesterases in all tissues examined were inhibited similarly, not only by theophylline but also by papaverine.

Animals↗
PubMed1982

Effects of particle size and perfusate composition on the uptake of colloidal gold by the rabbit thoracic aorta perfused in situ.

The influence has been investigated of particle size on the uptake of radioactive gold colloid by the rabbit thoracic aorta perfused in situ. Particles ranging in diameter from 14 nm to 40 nm were suspended in 0.9% NaCl and infused either at a pressure of 15 mm Hg for times of between 2 1/2 and 60 min or at pressure of between 15 and 160 mm Hg for 5 min. Uptake by the whole intima-media increased with perfusion time and hydrostatic pressure but did not depend on particle size. Radioactive assay of serial sections across the aortic wall also showed that particle size did not influence the distribution of tracer. An effect of perfusate composition on uptake was demonstrated in further experiments in which particles either 14 or 40 nm in diameter were suspended in pooled rabbit serum and infused at pressures of between 15 and 140 mm Hg for 5 min. Uptake and transmural distribution were again independent of particle size, but uptake was 4-5-fold less than when the particles were perfused in saline. Under all perfusion conditions radioactivity fell steeply across the intima and then rose gradually across the media and adventitia. Radioactivity in the outer media and adventitia increased with perfusion time but little change could be detected in intimal activity. In transmission electron micrographs, particles in the intima were not seen to penetrate the internal elastic lamella and in the outer media particles remained extracellular and did not enter collagen bundles. Autoradiographs showed that particles in the intima were uniformly distributed around the circumference of the vessel but in the outer media and adventitia particles usually clustered close to the vasa vasorum.

Animals↗
PubMed1990

Quantitation of collagen fibril cross-section profiles in aging human veins.

The cross-section profiles and the diameter distribution of collagen fibrils were examined quantitatively in normal human internal jugular veins at different ages (first, fifth, and eighth decades). All fibrils showed a regular cross-striation pattern of native-type collagen fibrils irrespective of their cross-section profiles. Irregularly outlined ("dysplastic") fibrillar profiles were observed among the normally occurring circular cross-section profiles. The frequency of such unusual fibrils significantly increased with age. This increase was more pronounced in the tunica media as compared with the tunica adventitia. In the tunica media diameters of collagen fibrils also generally increased with age. In the tunica adventitia, on the other hand, fibrillar diameters were not significantly altered at different ages. The results of this study indicate that the frequency of both the irregularly outlined fibrillar cross-section profiles and increased fibrillar diameters depends on age in normal vascular walls. Therefore, it is concluded that the occurrence of "dysplastic" fibrils is a physiologic age-related phenomenon rather than a morphologic sign of pathologic alteration of collagen. The higher frequency of irregularly outlined collagen fibrils in the tunica media may indicate a higher and/or altered synthetic behavior of smooth muscle cells when compared with fibroblasts of the tunica adventitia.

Adult↗
PubMed1995

Intimal neovascularization in human coronary atherosclerosis: its origin and pathophysiological significance.

To investigate the histopathological characteristics of the newly formed vessels in the atherosclerotic intima of human coronary arteries, we conducted postmortem angiography in 31 cases, including 11 with myocardial infarction. Vessels were examined three-dimensionally under the stereoscope. In addition, we evaluated 25 anterior descending coronary arteries unrelated to the occurrence of myocardial infarction by light microscopy using 3-mm stepwise sections and 5-microns serial sections. Histological alterations were analyzed morphometrically to determine the correlation between the degree of intimal neovascularization and the growth of the endothelium into the atherosclerotic intima from the adventitia or lumen. There was a significant positive correlation between the density of new vessels in the intima and the incidence of luminal stenosis, the extent of chronic inflammatory infiltrate, the formation of granulation tissue, or the atheromatous changes, whereas the vascular density decreased in the extensively hyalinized and calcified intima. The newly formed intimal vessels originated mainly from the adventitial vasa vasorum and also partly from the proper coronary lumen. The intimal vessels that originated from the adventitia occurred approximately 28 times more frequently than those that originated from the luminal side. The frequency of former vessels increased as the luminal stenosis became more severe, whereas the latter vessels were found most frequently in the presence of 40% and 50% stenosis. Vessels originating from the proper lumen were more often associated with fresh or old hemorrhage. We conclude that intimal neovascularization largely originates from the adventitia and is closely associated with the extent of coronary stenosis and the histological inflammatory reaction.

Adult↗
PubMed1989

Demonstration of plasminogen activator activity in the intima and media of the normal human aorta and other large arteries: immunological identification of the plasminogen activator(s).

The plasminogen activator activity (PAA) in extracts of the intima, media, and adventitia of the normal human aorta and other large arteries (carotid artery, renal artery and iliac artery) was studied with a sensitive, quantitative spectrophotometric assay using plasminogen and the chromogenic plasmin substrate S-2251. All layers of the arteries showed PAA which was highest in the adventitia, lowest in the media, while in the intima (aorta) PAA was intermediate, but much closer to that of the media. Plasminogen activator inhibition (PAI) was at the same level in all layers of the arteries studied. Plasmin inhibition (PI) was higher in adventitia than in intima (aorta), while in media the PI was intermediate. The PAA was due to the tissue-type plasminogen activator (t-PA), but not to the urokinase-type (u-PA), as judged by addition of respective antibodies. The relatively low PAA found in the intima of large arteries is therefore due to a low plasminogen activator and not a high plasminogen activator inhibitor activity or plasmin inhibitor level.

Adolescent↗
PubMed1990

Intravascular ultrasound imaging: in vitro validation and pathologic correlation.

Intravascular ultrasound imaging is a new method in which high resolution images of the arterial wall are obtained with use of a catheter placed within an artery. An in vitro Plexiglas well model was used to validate measurements of the luminal area, and an excellent correlation was obtained. One hundred thirty segments of fresh peripheral arteries underwent ultrasound imaging and the findings were compared with the corresponding histopathologic sections. Luminal areas determined with ultrasound imaging correlated well with those calculated from microscopic slides (r = 0.98). Three patterns were identified on the ultrasound images: 1) distinct interface between media and adventitia, 2) indistinct interface between media and adventitia but different echo density layers, and 3) diffuse homogeneous appearance. The types of patterns depended on the relative composition of the media and adventitia. Calcification of intimal plaque obscured underlying structures. Atherosclerotic plaque was readily visualized but could not always be differentiated from the underlying media.

Adult↗
PubMed2005

Extracellular superoxide dismutase overexpression reduces cuff-induced arterial neointimal formation.

The mechanisms of neointimal formation in cuff-injury models are still uncertain. To examine whether extracellular superoxide dismutase (EC-SOD) can reduce neointimal formation in a cuff-injury model, adenoviruses expressing EC-SOD (AxCAEC-SOD) or Escherichia coli beta-galactosidase (AxCALacZ) was injected between the cuff and the adventitia of rat femoral arteries. As a result, EC-SOD protein was effectively produced in the adventitia, as assessed by immunohistochemical staining. In comparison with cuff-treated control arteries and AxCALacZ-transfected arteries, neointimal formation was significantly reduced in AxCAEC-SOD-transfected arteries. Furthermore, proliferating smooth muscle cells in neointima and media were reduced by EC-SOD treatment. Similarly, augmented iNOS expression, apoptosis and collagen content in the vascular wall were also reduced by EC-SOD treatment. Reactive oxygen species (ROS) generation in tissue was reduced by EC-SOD expression, as assessed by dihydroethidium staining and coelenterazine chemiluminescence. These results suggest that ROS, especially superoxide anions at an adventitia, are responsible for neointimal formation in a cuff-injury model.

Animals↗
PubMed2006

Characterisation of progenitor cells in human atherosclerotic vessels.

Recent data from animal models has demonstrated that both endothelial and smooth muscle progenitor cells contribute to the development of atherosclerosis. However, no data exists concerning the presence of progenitor cells in human atherosclerotic vessels. In the present study, a range of normal and atherosclerotic human arteries were collected from patients undergoing coronary artery bypass surgery. Segments of internal mammary artery (normal controls), and segments of proximal ascending aorta with visible fatty streak were analysed. Immunofluorescence was used to detect a panel of progenitor cell markers. A small number of progenitor cells were identified within neointimal lesions and the adventitia with variable expression of CD34, stem cell antigen (Sca-1), c-kit and VEGF receptor 2 (VEGFR2) markers, but no CD133 expression. On average there was a two- to three-fold increase in progenitor cell number in the adventitia of atherosclerotic vessels compared with normal controls, with a significant difference (p<0.05) in the frequency of cells expressing VEGFR2. Thus, we have provided the first evidence that vascular progenitor cells exist within atherosclerotic lesions, and identified an increased number of progenitor cells in the adventitia of human atherosclerotic vessels. These cells might be a source for smooth muscle cells (SMCs), macrophages and endothelial cells (ECs) that form atherosclerotic lesions.

AC133 Antigen↗