Myocardial bridge associated with cardiovascular injuries in bovines adult of Canchim race.

BACKGROUND: The influence that myocardial bridge exercises over blood stream in the course of arterial segment under the bridge has been discussed by the scientific community. OBJECTIVE: To compare ultrastructural muscle tissue of myocardial bridge and the ventricular wall; to analyze the degree of injury to the tunica intima of the arterial segments, and look for possible changes that may precede or initiate the process of atherosclerotic lesions. METHODS: Forty Canchim bovine hearts were studied regarding alterations of the tunica intima from coronary arteries on the different myocardial bridge segments. For the microscopic examination, hematoxylin-eosin and fuchsin-resorcin staining following conventional microscope techniques were made. For the electronic microscopic examination, myocardial Bridge segments from twelve Canchim bovine hearts were collected from the ventricle wall and coronary artery and were processed according to conventional techniques. RESULTS: In the light microscopy, a higher frequency of lesions on prepontine and postpontine segments of the tunica intima was observed, compared to the pontine segment. Tunica intima thickenings were followed by a disarrangement on the internal elastic limitant lamina. These cells often presented their cytoplasmas engorged by lipidic drops, making up the so-called foam cells. Electronic microscopy revealed that the muscular fibers of the myocardial bridge are usually joined in a straight and smooth way presenting lateral branches with a greater number of mitochondria in the ventricular muscle than in the bridge. CONCLUSION: There are few differences between the muscle tissues studied; intimae lesions are less frequent in pontine regions compared to pre and post-pontine regions.

Ponte miocárdica associada a lesões cardiovasculares em bovinos adultos da raça Canchim / Myocardial bridge associated with cardiovascular injuries in bovines adult of Canchim race / Puente miocárdico asociado a lesiones cardiovasculares en bovinos adultos de la raza canchim

FUNDAMENTO: A influência que a ponte miocárdica exerce sobre a corrente sanguínea no curso do segmento arterial sob a ponte tem sido objeto de discussão pela comunidade científica. OBJETIVO: Comparar o tecido muscular ultraestrutural da ponte miocárdica e a parede ventricular; analisar o grau de lesão da camada íntima dos segmentos arteriais e investigar possíveis mudanças que podem preceder ou iniciar o processo de lesões ateroscleróticas. MÉTODOS: Quarenta corações bovinos da raça Canchim foram estudados em relação às alterações da camada íntima das artérias coronarianas nos diferentes segmentos de ponte miocárdica. Para o exame microscópico, foram feitas colorações por hematoxilina-eosina e fucsina-resorcina seguindo técnicas microscópicas convencionais. Para o exame de microscopia eletrônica, os segmentos da ponte miocárdica de doze corações bovinos Canchim foram coletados a partir da parede ventricular e da artéria coronariana e foram processados de acordo com técnicas convencionais. RESULTADOS: Na microscopia de luz, foi observada maior frequência de lesões em segmentos pré-ponte e pós-ponte da camada íntima, em comparação ao segmento ponte. Espessamentos da camada íntima foram seguidos por um desarranjo na lâmina limitante elástica interna. Essas células frequentemente apresentaram seus citoplasmas ingurgitados por gotas lipídicas, compondo as chamadas células de espuma. A microscopia eletrônica revelou que as fibras musculares da ponte miocárdica geralmente se unem de forma reta e lisa apresentando ramos laterais com um número maior de mitocôndrias no músculo ventricular do que na ponte. CONCLUSÃO: Há poucas diferenças entre os tecidos musculares estudados; lesões da camada íntima são menos frequentes em regiões da ponte em comparação com as regiões pré e pós-ponte.

BACKGROUND: The influence that myocardial bridge exercises over blood stream in the course of arterial segment under the bridge has been discussed by the scientific community. OBJECTIVE: To compare ultrastructural muscle tissue of myocardial bridge and the ventricular wall; to analyze the degree of injury to the tunica intima of the arterial segments, and look for possible changes that may precede or initiate the process of atherosclerotic lesions. METHODS: Forty Canchim bovine hearts were studied regarding alterations of the tunica intima from coronary arteries on the different myocardial bridge segments. For the microscopic examination, hematoxylin-eosin and fuchsin-resorcin staining following conventional microscope techniques were made. For the electronic microscopic examination, myocardial Bridge segments from twelve Canchim bovine hearts were collected from the ventricle wall and coronary artery and were processed according to conventional techniques. RESULTS: In the light microscopy, a higher frequency of lesions on prepontine and postpontine segments of the tunica intima was observed, compared to the pontine segment. Tunica intima thickenings were followed by a disarrangement on the internal elastic limitant lamina. These cells often presented their cytoplasmas engorged by lipidic drops, making up the so-called foam cells. Electronic microscopy revealed that the muscular fibers of the myocardial bridge are usually joined in a straight and smooth way presenting lateral branches with a greater number of mitochondria in the ventricular muscle than in the bridge. CONCLUSION: There are few differences between the muscle tissues studied; intimae lesions are less frequent in pontine regions compared to pre and post-pontine regions.

FUNDAMENTO: La influencia que el puente miocárdico ejerce sobre la corriente sanguínea en el transcurso del segmento arterial bajo el puente, ha sido objeto de discusión por parte de la comunidad científica. OBJECTIVO: Comparar el tejido muscular ultra estructural del puente miocárdico y la pared ventricular; analizar el grado de lesión de la capa íntima de los segmentos arteriales e investigar posibles cambios que pueden preceder o iniciar el proceso de lesiones ateroscleróticas. MÉTODO: Cuarenta corazones bovinos de la raza Canchim fueron estudiados con respecto a las alteraciones de la capa íntima de las arterias coronarias en los diferentes segmentos del puente miocárdico. Para el examen microscópico, se hicieron coloraciones por hematoxilina-eosina y fucsina-resorcina secundando las técnicas microscópicas convencionales. Para el examen de microscopía electrónica, los segmentos del puente miocárdico de doce corazones de bovinos de la raza Canchim, fueron recolectados así como de la pared ventricular y de la arteria coronaria y fueron procesados de acuerdo con las técnicas convencionales. RESULTADOS: En la microscopía de luz, observamos una mayor frecuencia de lesiones en segmentos de pre puente y pos-puente de la capa íntima, en comparación con el segmento puente. Los espesamientos de la capa íntima vinieron acompañados por un desarreglo en la lámina limitante elástica interna. Esas células a menudo presentan sus citoplasmas ingurgitados por gotas lipídicas, lo que compone las llamadas células de espuma. La microscopía electrónica reveló que las fibras musculares del puente miocárdico generalmente se unen de forma recta y lisa, presentando ramas laterales con un número mayor de mitocondrias en el músculo ventricular que en el puente. CONCLUSIONES: Existen pocas diferencias entre los tejidos musculares estudiados. Las lesiones de la capa íntima son menos frecuentes en las regiones del puente en comparación con las regiones pre y pos puente.

The effects of palm oil tocotrienol-rich fraction supplementation on biochemical parameters, oxidative stress and the vascular wall of streptozotocin-induced diabetic rats.

OBJECTIVE: This study examined the effects of palm oil tocotrienol-rich fractions on streptozotocin-induced diabetic rats. METHODS: Animals were divided into three groups: (i) normal non-diabetic (NDM), (ii) diabetic treated (tocotrienol-rich fractions - TRF) and (iii) diabetic untreated (non-TRF). The treatment group received oral administration of tocotrienol-rich fractions (200 mg/kg body weight) daily for eight weeks. The normal non-diabetic and the diabetic untreated groups were fed standard rat feed. Blood glucose and lipid profiles, oxidative stress markers and morphological changes of the thoracic aorta were evaluated. RESULTS: Tocotrienol-rich fractions treatment reduced serum glucose and glycated hemoglobin concentrations. The tocotrienol-rich fractions group also showed significantly lower levels of plasma total cholesterol, low-density lipoprotein cholesterol, and triglyceride, as compared to the untreated group. The tocotrienol-rich fractions group had higher levels of high-density lipoprotein cholesterol, as compared to the untreated group. Superoxide dismutase activity and levels of vitamin C in plasma were increased in tocotrienol-rich fractions-treated rats. The levels of plasma and aorta malondealdehyde + 4-hydroxynonenal (MDA + 4-HNE) and oxidative DNA damage were significant following tocotrienol-rich fractions treatment. Electron microscopic examination showed that the normal morphology of the thoracic aorta was disrupted in STZ-diabetic rats. Tocotrienol-rich fractions supplementation resulted in a protective effect on the vessel wall. CONCLUSION: These results show that tocotrienol-rich fractions lowers the blood glucose level and improves dyslipidemia. Levels of oxidative stress markers were also reduced by administration of tocotrienol-rich fractions. Vessel wall integrity was maintained due to the positive effects mediated by tocotrienol-rich fractions.

The effects of palm oil tocotrienol-rich fraction supplementation on biochemical parameters, oxidative stress and the vascular wall of streptozotocin-induced diabetic rats

OBJECTIVE: This study examined the effects of palm oil tocotrienol-rich fractions on streptozotocin-induced diabetic rats. METHODS: Animals were divided into three groups: (i) normal non-diabetic (NDM), (ii) diabetic treated (tocotrienol-rich fractions - TRF) and (iii) diabetic untreated (non-TRF). The treatment group received oral administration of tocotrienol-rich fractions (200 mg/kg body weight) daily for eight weeks. The normal non-diabetic and the diabetic untreated groups were fed standard rat feed. Blood glucose and lipid profiles, oxidative stress markers and morphological changes of the thoracic aorta were evaluated. RESULTS: Tocotrienol-rich fractions treatment reduced serum glucose and glycated hemoglobin concentrations. The tocotrienol-rich fractions group also showed significantly lower levels of plasma total cholesterol, low-density lipoprotein cholesterol, and triglyceride, as compared to the untreated group. The tocotrienol-rich fractions group had higher levels of high-density lipoprotein cholesterol, as compared to the untreated group. Superoxide dismutase activity and levels of vitamin C in plasma were increased in tocotrienol-rich fractions-treated rats. The levels of plasma and aorta malondealdehyde + 4-hydroxynonenal (MDA + 4-HNE) and oxidative DNA damage were significant following tocotrienol-rich fractions treatment. Electron microscopic examination showed that the normal morphology of the thoracic aorta was disrupted in STZ-diabetic rats. Tocotrienol-rich fractions supplementation resulted in a protective effect on the vessel wall. CONCLUSION: These results show that tocotrienol-rich fractions lowers the blood glucose level and improves dyslipidemia. Levels of oxidative stress markers were also reduced by administration of tocotrienol-rich fractions. Vessel wall integrity was maintained due to the positive effects mediated by tocotrienol-rich fractions.

Hypotrophy of conduit artery walls of the offspring of nitric oxide-defective rats.

The objective of the present study was to investigate the structure of the arterial walls of the offspring stemming from nitric oxide (NO)-defective hypertensive parents. The parents were treated with NG-nitro-L-arginine methyl ester (40 mg kg-1 day-1) for 5 weeks. Blood pressure was measured noninvasively in six 30-day-old rats and nine age-matched controls. The cardiovascular system was perfused with glutaraldehyde at 120 mmHg. The thoracic aorta and carotid artery were processed for electron microscopy, and geometry was determined by light microscopy. Endothelial cells, smooth muscle cells (SMC) and extracellular matrix (ECM) were determined by the point counting method in electron micrographs of the carotid artery. The blood pressure of experimental offspring was 150.0 +/- 2.3 vs 104.6 +/- 2.1 mmHg (P < 0.01) for the controls and their heart/body weight ratio of 3.9 +/- 0.1 vs 4.4 +/- 0.2 (P < 0.05) for the controls indicated cardiac hypotrophy. The wall thickness (tunica intima and media) of the thoracic aorta and carotid artery of experimental offspring was decreased to 78.9% (P < 0.01) and 83.8% (P < 0.01), respectively, compared to controls, as confirmed by a respective cross-sectional area of 85.3% (P < 0.01) and 84.1% (P < 0.01). The wall thickness/inner diameter ratio was reduced to 75% (P < 0.01) in the thoracic artery and to 81.5% (P < 0.01) in the carotid artery. No change in endothelial cell volume density or ECM was observed in the tunica intima of the carotid artery, and SMC volume density was lower in the tunica media (37.6 +/- 0.9 vs 44.7 +/- 1.1% for controls, P < 0.01), indicating compromised SMC development. Interference with arginine metabolism, a decrease in NO, and other factors are possible mechanisms underlying the structural alterations of the cardiovascular system of offspring from NO-defective hypertensive rats.

Elastic fibers in saphenous varicose veins.

The purpose of this study is to describe the elastic fibers of varicose collateral saphenous veins. Sections were obtained from venous segments of patients with essential varices and stained with resorcin-fuchsin for elastic system fibers and analyzed with laser scanning microscopy after Evans blue staining. Vein portions (270 microm) were classified as without thickening, with a cushion, or with a diffuse thickening. The elastic material density of the intima (Dei) and media (Dem) were tested for differences by the Kruskal-Wallis test. Diffuse thickening (87.1+/-8.6 microm) represents 54.5% of the segment. Cushion occupies 23.5% with 42.4+/-4.66 microm. The elastic network present in the cushion is formed by elastic fibers of different diameters that branch into delicate oxytalan fibers in association with the smooth muscle cells. The diffuse thickening elastic network varies from elastic lamellae and delicate oxytalan fibers related to the intima smooth muscle cell bundles to fragmented elastic fibers in the collagenous areas. Dei increases as the intima enlarges (10.19, 14.63, and 16.01, respectively to without thickening, cushion, diffuse thickening). In the media, the elastic network encircles the circular muscle bundles connecting them to the elastic internal lamina and to elastic fibers in the adventitia. Smooth muscle cells were coiled by numerous oxytalan fibers and the elastic fibers are irregular and fragmented. In the sclerotic portions, the elastic fibers are sparse. No correlation was found between Dei and Dem. The important thickening of varicose vein intima shows increasing quantities of elastic material formerly associated with smooth muscle cells. In the media, the elastic network around smooth muscle cell bundles is disrupted and the Dem diminishes as the media becomes sclerotic.

A comparative study of policosanol vs lovastatin on intimal thickening in rabbit cuffed carotid artery.

Policosanol is a cholesterol-lowering drug isolated from sugar cane wax, which acts by inhibiting cholesterol biosynthesis. Previous studies have demonstrated that policosanol inhibited smooth muscle cell (SMC) proliferation in the cuffed carotid artery of the rabbit and in arterial wall damage induced by forceps in the central artery of the ear of rabbits. The present study was undertaken to compare the effects of policosanol and lovastatin on SMC proliferation in the cuffed carotid artery of rabbits. Collars were placed around the left carotid for 7 and 15 days. The contralateral artery was sham operated. We studied eight experimental groups: two controls groups receiving vehicle for 7 and 15 days, respectively, a satellite sham operated control group, four groups treated with policosanol at 5 and 25 mg kg(-1)for 7 and 15 days and a reference group receiving lovastatin at 20 mg kg(-1)for 15 days. Samples of arteries were examined by light and electron microscopy. To evaluate intimal thickening the cross-sectional areas of intima and media were measured. Neointima was significantly reduced in treated animals compared with controls, but the reduction in lovastatin animals was significantly lower than in policosanol-treated groups. The SMC proliferation was studied by the immunohistochemical detection of proliferating cell nuclear antigen and the reduction observed in policosanol-treated rabbits was significantly larger than in lovastatin-treated animals. It is concluded that the protective effect of policosanol against neointima formation in this experimental model was slightly better than that of lovastatin.

Immunolabeling of type IV collagen, laminin, and alpha-smooth muscle actin cells in the intima of normal and varicose saphenous veins.

Smooth muscle cells (SMC) of normal and varicose human saphenous intima were studied on cryostat sections by immunohistochemistry with alpha-smooth muscle actin (ASMA), type IV collagen, and laminin antibodies and also by transmission electron microscopy. The findings suggest two structurally distinct subtypes of smooth muscle cells with thin and thicker external lamina. Thin external lamina SMC were characterized by laminin, type IV collagen, weaker external lamina reactivity, and intense cytoplasmic alpha-smooth muscle actin immunoreactivity. Ultrastructurally, they exhibited abundant cytoplasmic microfilaments and thin external lamina. These cells were found isolated or, more frequently, clustered in fascicles close to the subendothelium in focal or zonal cushions, or in diffuse enlargement of the intima. In contrast, thicker external lamina smooth muscle cells were intensely immunolabeled for laminin and collagen IV, showing irregular cytoplasmic ASMA reaction. Single or clustered thicker external lamina SMC were seen predominantly in zonal cushions and in intima diffuse enlargement. It is very likely that these cells secrete these matrices in a nonpolarized fashion. The thicker external lamina of these SMCs showed a fine granular amorphous aspect sometimes intermingled with microfibrils. These external lamina were interposed between neighboring cells and exposed to collagen fibrils and elastic fibers. The cells also exhibited rarefaction of the cytoplasmic filaments. Intermediary cells exhibiting both features were rarely seen. Thicker external lamina SMC should be discussed in the context of an adaptive/proliferative response leading to dysfunction of the fibroelastic properties of the vein wall.

Effect of policosanol on intimal thickening in rabbit cuffed carotid artery.

We studied the effect of policosanol on smooth muscle cell proliferation in the cuffed carotid artery of the rabbit. Policosanol is a mixture of higher aliphatic primary alcohols isolated from sugar cane wax, with cholesterol lowering effects proved in experimental models and patients with type II hypercholesterolemia. It acts by inhibiting cholesterol biosynthesis. The positioning of a nonocclusive silicone collar around the rabbit carotid artery results in the formation of a neointima. We wished to determine whether policosanol orally administered prevented intimal thickening. Collars were placed around the left carotid for 15 days. The contralateral artery was sham operated. We included three experimental groups: a control received vehicle and two others policosanol at 5 and 25 mg Kg until sacrificed. Samples of arteries were examined by light and electron microscopy. To evaluate intimal thickening the cross-sectional area of intima and media were measured. Neointima was significantly reduced in policosanol-treated animals compared with controls. The smooth muscle cell proliferation was studied by the immunohistochemical detection of proliferating cell nuclear antigen and a significant reduction was observed in policosanol treated rabbits. It is concluded that policosanol has a protective effect on the neointima formation in this experimental model.

Study on optic microscope of the muscle and elastic components of the aorto-iliac bifurcation septum and initial segment of the middle sacral artery.

In this work the aorto-iliac bifurcation septum and the initial segment of the middle sacral artery were analyzed through optic microscope. 20 anatomical pieces of corpses from subjects of both sexes aging from 20 to 33 years were examined. After collection of pieces and fixation in formaline for 48 hours, histological sections of 20 microns were made and stained with the methods of Weigert, Verhoeff and Picrofucsine of Van Gieson. It was observed that the middle sacral artery arises from the posterior aortic wall laterally to the aorto-iliac bifurcation septum. The sequential analysis of the sections showed that the septum is lined by a thickening of connective tissue along its length and elastic fibers predominate on its central portion. Bundles of muscle fibers prevail on the lateral and posterior regions. It was observed, above the origin of the middle sacral artery, a reorganisation of tissues which represents, more caudally, the ostium of the artery. It was verified that the middle sacral artery arises at the aorto-iliac bifurcation septum, which is a transitional region and should be classified of mixed type and called aorto-septo-sacral transition.

Comparison of sarcoplasmic reticulum characteristics in aortic smooth and ventricular muscles using chemically skinned preparations.

The active Ca2+ transport and the kinetics of Ca2+ efflux in sarcoplasmic reticulum (SR) of skinned aortic smooth muscle cells are compared with those in SR of skinned ventricular muscle cells. 45Ca uptake was measured at pCa 6.6 in the presence of 10 mM of K oxalate from 2 to 30 min. Unstimulated and Ca2+ stimulated Ca2+ efflux were assessed on Ca2+ desaturation curves performed in skinned cells preloaded with 45Ca in the absence of K oxalate. Results demonstrate that SR in aortic smooth muscle cells compared with SR in ventricular cells has: a) 2 times lower initial phase of Ca2+ uptake, b) 10 times lower enclosed volume, c) higher rate of unstimulated Ca2+ efflux and d) higher plus more sustained release of Ca2+ induced by Ca2+. It is also proved that the stimulated release of Ca2+ can be suppressed by 0.6 mM of ryanodine in aortic smooth muscle and by 50 microM of ruthenium red in ventricular muscle. This work provides direct measurements of Ca2+ transport capacity and of Ca2+ release of in situ sarcoplasmic reticulum. It quantifies the functional differences between vascular smooth and ventricular muscles.