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PubMedDate not supplied

Vascular homografts for vessel substitution in skeletal and soft tissue sarcomas of the limbs.

Large vessel involvement by skeletal and soft tissue sarcomas of the extremities does not change the modern limb sparing surgery for those neoplasms. An arterial and, if the vein is open, a venous bypass should always be offered to any patient young or old, with high or low grade sarcoma, because preserving the limb permits quicker rehabilitation, which is particularly useful in the case of a short life expectancy. In 650 cases of skeletal sarcomas, 10 arterial (1.5%) and four venous bypasses were done, all with autologous veins but one in PTFE; we had no problems except a silent arterial occlusion. Of 1000 patients with soft tissue sarcomas, 32 (3%) had vessel involvement permitting limb sparing surgery. The arterial bypass, which is the limb-saving operation, was performed 16 times with a PTFE with one early occlusion and four cases of prosthesis infection, with two amputations despite redo operation with an autologous vein. The more recent 16 cases were, therefore, always done with biological vessel substitution--autologous vein or tissue bank vessel--with only one infection that healed without operation and one case of homograft rupture followed by amputation. Since 1999 in all 13 resected cases with an open vein, we did the arterial and the venous bypass (twice PTFE, six autologous vein, and five bank vessel) with the aim of avoiding postoperative venous hypertension, but only four of the venous bypasses remained open. Venous bypasses are a harmless, but still experimental, procedure.

Arteries↗
PubMed2005

Curvature affects Doppler investigation of vessels: implications for clinical practice.

In clinical practice, blood velocity estimations from Doppler examination of curved vascular segments are normally different from those of nearby straight segments. The observed "accelerations," sometimes considered as a sort of stochastic disturbances, can actually be related to very specific physical effects due to vessel curvature (i.e., the development of nonaxial velocity [NAV] components) and the spreading of the axial velocity direction in the Doppler sample volume with respect to the insonation axis. The relevant phenomena and their dependence on the radius of curvature of the vessels and on the insonation angle are investigated with a beam-vessel geometry as close as possible to clinical setting, with the simplifying assumptions of steady flow, mild vessel curvature, uniform ultrasonic beam and complete vessel insonation. The insonation angles that minimize the errors are provided on the basis of the study results.

Algorithms↗
PubMed2005

Contribution of bone marrow-derived cells to blood vessels in ischemic tissues and tumors.

Vessels are formed during embryonic development through three distinct processes. Angiogenesis and arteriogenesis involve the remodeling of established capillary networks and arterioles, while vasculogenesis involves the differentiation of mesodermal progenitor cells called angioblasts into mature endothelial cells. Until recently, postnatal vessel development was felt to occur exclusively through angiogenesis or arteriogenesis. However, recent studies using experimental tumor and ischemia models have raised controversy regarding whether vasculogenesis occurs in postnatal vessel development, with some studies suggesting the possibility and others refuting it. Here, we summarize the process of embryonic vessel development and review studies investigating the role of postnatal vasculogenesis in vessel formation in adult ischemia and tumors. We then focus on studies in which wild-type and genetically modified vascular progenitor cells have been investigated as possible cellular therapies for tumors or ischemia. We also take note of key issues that will need to be understood about the biology of vasculogenesis before cellular therapies utilizing vascular progenitor cells can be finally taken from the bench to the bedside.

Animals↗
PubMed1976

Intramyocardial small-vessel disease in chronic alcoholism.

A morphologic study of the small (50 to 200 micron) intramyocardial coronary arteries was performed. The cases chosen for study were selected from a relatively young group of patients without clinical evidence of alcoholic cardiomyopathy or pathologic evidence of large coronary artery disease, in order to evaluate alterations in the small vessels which could possibly be attributed to the chronic alcoholic state. Five basic vascular abnormalities were described. The most common alteration found in all nine cases was vascular wall edema (48 per cent), followed by perivascular fibrosis (42 per cent), vascular sclerosis (36 per cent), subendothelial humps (13 per cent), and vascular wall inflammation (11 per cent). The significance and pathogenesis of these changes were discussed. Primary endothelial cell damage was proposed as a common pathogenic mechanism for all five types of vascular abnormality. It was suggested that following endothelial damage, fluid and macromolecules penetrate into the vessel wall or into the perivascular space where, by incompletely understood processes, they induce vascular wall myocytes to produce collagen, elastin, and basement membrane-like substances. Evidence supporting this mechanism was derived from the common observation of vascular wall edema, from the occasional presence of erythrocytes and leukocytes within the vessel wall, and from experimental data in the literature. Several possible etiologic agents were implicated in the pathogenesis of endothelial and vessel wall injury. These included alcohol itself, acetaldehyde, biogenic amines, and magnesium deficiency. It is probable, however, that there are multiple etiologic factors which affect the small cardiac vessels of the chronic alcoholic. Finally, the proposal was advanced that the nonspecific pathology of the myocardium in chronic alcoholism may be a result of ischemia secondary to disease of the small intramyocardial coronary ateries.

Adult↗
PubMed1996

Nitric oxide production by coronary conductance and resistance vessels in hypercholesterolemia patients.

NG-monomethyl-L-arginine (L-NMMA), a specific inhibitor of nitric oxide (NO) synthesis, was used to investigate the effects of inhibition of NO synthesis on the coronary conductance and resistance vessels in hypercholesterolemic patients. Acetylcholine (3 and 30 micrograms/min) was administered to 10 hypercholesterolemic and 10 control patients before and after L-NMMA (25 micromol/min) infusion. Epicardial coronary diameter was measured by quantitative angiography, and coronary blood flow (CBF) was derived from Doppler flow-velocity and coronary diameter measurements. In hypercholesterolemic patients, acetylcholine-induced dilation of epicardial arteries was attenuated, and the percentage increase in CBF caused by acetylcholine was smaller than that in control patients. L-NMMA attenuated acetylcholine-induced dilation of epicardial arteries in control patients. L-NMMA had no effect on CBF responses to acetylcholine in both patient groups. L-NMMA significantly decreased the baseline coronary diameter and CBF in both groups. These results indicated that hypercholesterolemia impaired the acetylcholine-induced dilation of the conductance and resistance coronary vessels. This impairment in the conductance vessels was dependent on NO production; that of resistance vessels was not. The basal release of NO in conductance and resistance vessels was preserved in hypercholesterolemic patients.

Acetylcholine↗
PubMed1999

Augmentation of vessel squeezing at coronary-myocardial bridge by nitroglycerin: study by quantitative coronary angiography and intravascular ultrasound.

BACKGROUND: Nitroglycerin is known to augment vessel wall squeezing at the site with coronary-myocardial bridging (CMB). This study was designed to define the mechanism of nitroglycerin-induced augmentation of CMB in clinical settings. METHODS: We analyzed nitroglycerin reactivity at the site with CMB in 39 patients. Maximal and minimal diameters of CMB during a cardiac cycle were measured by quantitative angiography before and after intracoronary administration of 250 microgram nitroglycerin. In 15 patients, CMB sites were observed by intravascular ultrasound to determine the intimal thickness and the time-serial change in vessel area. RESULTS: Before nitroglycerin, CMB was demonstrated with angiography in 25 patients, and the remaining 14 patients showed CMB after nitroglycerin. The maximal diameter during diastole increased from 1. 4 +/- 0.4 mm to 1.9 +/- 0.4 mm after nitroglycerin, whereas the minimal diameter during systole decreased from 1.0 +/- 0.4 mm to 0.7 +/- 0.4 mm (P <.01). Thus nitroglycerin augmented the percent vessel narrowing during systole from 24% +/- 21% to 65% +/- 16% (P <.01). Under these conditions, intravascular ultrasound showed the reduction of the cross-sectional area of the sites with CMB by -38% +/- 16% (P <.01) during systole, and this phenomenon continued to early diastole (-30% +/- 16%). The intimal thickness was 0.32 +/- 0. 10 mm, which suggests the absence of atherosclerotic disease at CMB sites. CONCLUSIONS: These results indicate that nitroglycerin-induced augmentation of the percent narrowing of CMB can be derived from further systolic compression of the vessel lumen as well as diastolic expansion, probably because of the increase in vessel compliance after nitroglycerin. We suggest that the delayed dilation of coronary lumen during the early diastole may contribute to the occurrence of myocardial ischemia.

Adult↗
PubMed1997

Effects of stenting of recent or chronic coronary occlusions on late vessel patency and left ventricular function.

Due to high rates of late vessel reocclusion, balloon angioplasty of recent or chronic coronary occlusions is not associated with a sustained improvement in left ventricular function. Recent studies have suggested that stent implantation at coronary occlusions significantly reduces late vessel occlusion. We thus designed a study to analyze the effect of stent implantation at coronary occlusions on late vessel potency and left ventricular function. Twenty-four consecutive patients with recent or chronic coronary occlusions had successful stent implantation and were enrolled in a 6-month angiographic follow-up program. Contrast left ventricular cineangiography, at baseline and 6-month follow-up, as well as preprocedural, postprocedural, and follow-up angiograms analyzed with quantitative angiography were available in 22 of the patients (92%). At follow-up, no vessel reocclusion was observed and 32% of the patients, as analyzed by the >50% diameter stenosis criterion, had restenosis. There was a significant improvement in global left ventricular function with a decrease in both left ventricular end-diastolic volume index (LVEDVI, p <0.01) and left ventricular end-systolic volume index (LVESVI, p <0.0001) and an increase in left ventricular ejection fraction (LVEF, p <0.0001). Similarly, regional wall motion in the territory of the recanalized artery was also significantly improved (p <0.05). These effects were associated with a reduction in left ventricular filling pressure (p <0.0001). Stent implantation following balloon angioplasty of recent or chronic coronary occlusion is associated with a low rate of late vessel reocclusion, a reduction in cardiac volume, and an increase in ejection fraction. Such effects on left ventricular volumes could have a significant impact on patient survival.

Angioplasty, Balloon, Coronary↗
PubMed2000

Endogenous factors involved in regulation of tone of arterial vasa vasorum: implications for conduit vessel physiology.

The walls of conduit blood vessels are nourished by diffusion of oxygen from luminal blood and from the vasa vasorum. The vasa vasorum, or 'vessels of a vessel', form a network of microvessels that lie in the adventitia and penetrate the outer media of the host vessel wall. Although the importance of the vasa vasorum in providing nutritional support is not well defined, obstruction of blood flow through these vessels has been implicated in the pathogenesis of certain cardiovascular diseases including atherosclerosis. This review focuses on the mechanisms that regulate tone in the vasa vasorum of large arteries and the functional implications of changes in reactivity of vasa vasorum.

Animals↗
PubMed2004

A model based method for retinal blood vessel detection.

Retinal blood vessels are important structures in ophthalmological images. Many detection methods are available, but the results are not always satisfactory. In this paper, we present a novel model based method for blood vessel detection in retinal images. It is based on a Laplace and thresholding segmentation step, followed by a classification step to improve performance. The last step assures incorporation of the inner part of large vessels with specular reflection. The method gives a sensitivity of 92% with a specificity of 91%. The method can be optimized for the specific properties of the blood vessels in the image and it allows for detection of vessels that appear to be split due to specular reflection.

Algorithms↗
PubMed1979

Automated image analysis for measurements of morphological reactions of blood vessels of the microvascular system.

Using a modification of the Mg-ATPase reaction, the arterial blood vessels of the microcirculatory bed of the rat including the smallest precapillary vessels are visualized in a grey-level difference against their environment which permits to utilize the automatic image analyser QUANTIMET 720 and the programmable desk-top calculator HEWLETT-PACKARD 9100B. The article describes the method for preparing the sections, the measuring procedure, and the statistical verification of the results by means of the computer assisted two-way analysis of variance as well as studies demonstrating the reliability of the method. It is concluded that the procedure at heart, skeletal muscle and pancreas specimens of the rat demonstrates reliably and effectively changes of the number of vessels and the projected whole vessel wall area as well as differences of enzyme activities. Thus it is possible to detect structural wall reactions and enzyme histochemical changes of arterial blood vessels of the microvasculatory bed including its smallest precapillaries which have been practically inaccessible to histomorphometrical investigations in the past.

Adenosine Triphosphatases↗
PubMed1992

Laparoscopy for nonpalpable testes in childhood: is inguinal exploration also necessary when vas and vessels exit the inguinal ring?

Laparoscopy has proved to be a safe method for determining the status for nonpalpable testes. In a combined series 52 boys with 57 nonpalpable testes were evaluated laparoscopically. Of the 57 nonpalpable testes 26 were located above the internal inguinal ring (abdominal), 4 were found more distally, and blind-ending vas and vessels terminated in the abdomen in 3, and beyond the internal ring (vanished testes) in 24. Of 29 abdominal testes primary orchiopexy was performed in 15, 4 were removed, the vessels were transected (Fowler-Stephens) in 5, stage 1 of staged repairs was done in 2, distinct laparoscopic evidence of blind-ending vessels and vas obviated further surgery in 2, and testis was not identified either laparoscopically or by abdominal exploration. Finally, inguinal exploration in 28 children in whom vas and vessels were found to exit the internal ring resulted in localization of 4 testes that were brought into the scrotum. Removal of 23 testicular nubbins and their evaluation histologically resulted in identification of viable tubular structures in 3. We recommend inguinal exploration in all children who on laparoscopy are found to have vas and vessels exit the internal ring, and removal of testicular nubbins.

Blood Vessels↗
PubMed1995

Direct measurement of retinal vessel diameter: comparison with microdensitometric methods based on fundus photographs.

A new method for the direct measurement of retinal vessel diameter was developed and the results were compared with those of two computer-assisted semiautomatic microdensitometric methods. The direct measurement method was based on automated detection of vessel edges by processing the one-dimensional retinal image obtained by a linear image sensor set in a fundus camera; results are obtained in real-time. Thirty-eight points on 36 vessels (15 points on arteries and 23 points on veins) of two normal volunteers (four eyes) were selected as the measurement points. Two observers measured the vessel diameters at these points and the interobserver variation of the direct method and the microdensitometric methods was compared. The coefficient of variation and the interobserver variation of the direct method for all measurements were 1.71 + 1.13% and 2.25 + 1.92%, respectively. There was no significant difference between the measured values for the two observers with the direct method (paired t-test, P > 0.05), and the interobserver variation of the direct method was smaller than those of the microdensitometric methods. This newly developed direct method for measurement of retinal vessel diameter not only avoids systematic errors that result from film development or the characteristics of the film, but also generates reproducible results in real-time and small interobserver variation.

Adult↗
PubMed1999

The expression of basic fibroblast growth factor (bFGF) in tumor-associated stromal cells and vessels is inversely correlated with non-small cell lung cancer progression.

Tumor progression results from complex interactions between tumor and tumor-associated host tissue. Basic fibroblast growth factor (bFGF), via activation of its receptor, FGFR-1, has been postulated to be an important inducer of host stromal response and angiogenesis. To assess the putative role of tumor-associated stromal cells and vessels in tumor progression, we studied non-small cell lung cancer (NSCLC) from 84 patients, including 51 squamous cell carcinomas and 33 nonsquamous cell carcinomas, by immunohistochemical detection. bFGF and FGFR-1 immunoreactivity was observed in tumor and in tumor-associated stromal cells and vessels. The expression of bFGF and FGFR-1 in stromal cells was higher in squamous than in non-squamous cell carcinomas (respectively, P = .007 and P = .0004). We found that bFGF and FGFR-1 expression in tumor and tumor-associated stromal cells and vessels was directly correlated with host stromal response, as assessed by intratumoral extension of stroma, but not with angiogenic response, as assessed by microvessel count. Although FGFR-1 expression of tumor cells was directly correlated with T-stage (P = .03), bFGF expressions of tumor-associated stromal cells and vessels were inversely correlated with lymph node metastasis (respectively, P = .0001 and P = .0002) and advanced pathological stage (respectively, P = .03 and P = .01). These findings suggest that bFGF might mediate host stromal response in NSCLC and that the expression of bFGF in tumor-associated stromal cells and vessels might have an inhibitory role in NSCLC progression.

Aged↗
PubMed1987

Occlusion of bridging or avulsed retinal vessels by repeated photocoagulation.

A technique is described for occlusion of bridging vessels associated with retinal breaks, and recurring vitreous hemorrhage. Argon laser photocoagulation, applied around and to the vessel in repeated sessions, produces scarring and progressive thinning of the retina until laser energy absorbed in the deep pigmented layers can reach the vessel and occlude it. Seventeen patients presenting with vitreous hemorrhage from bridging vessels were treated. Vitreous hemorrhage recurred in only two patients, one of whom had not returned for completion of treatment. The authors conclude that repeated argon laser photocoagulation is a safe, simple, and effective method for preventing recurrent vitreous hemorrhage from bridging vessels.

Aged↗
PubMed1992

Preservation of nerve fiber layer by retinal vessels in glaucoma.

The authors evaluated the correlation between various parameters and the local preservation of the retinal nerve fiber layer in 156 glaucomatous eyes. A vessel-associated preservation of the nerve fiber layer was observed in 45 of the 156 glaucomatous eyes. The presence of "straight" retinal vessels (either arterioles or large venules) and "tortuous" retinal vessels (large or small venules) inside of the scleral ring was correlated with the local preservation of the nerve fiber layer (P less than 0.001 and P less than 0.05, respectively). A local elevation of the floor of the cup was also correlated with the preservation of the nerve fiber layer (P less than 0.01). However, no correlation existed between either the preservation of the nerve fiber layer and the type of glaucoma, sex or age of patient, tilting of the disc, cilioretinal vessel, vertical cup-to-disc ratio, refractive error, disc size, distance between the disc and foveola, or the index of ovalness of the disc. These results suggest that retinal vessels in the disc significantly influence the vulnerability of the nerve fibers to glaucomatous damage.

Adult↗
PubMed2002

Ultrasound-based vessel wall tracking: an auto-correlation technique with RF center frequency estimation.

Vessel diameter is related to the distending blood pressure, and is used in estimations of vessel stiffness parameters. The vessel walls can be tracked by integrating wall velocities estimated by ultrasound (US) Doppler techniques. The purpose of this work was to evaluate the performance of the modified autocorrelation estimator when applied on vessel wall motion. As opposed to the conventional autocorrelation method that only estimates the mean Doppler frequency, the modified autocorrelation method estimates both the mean Doppler frequency and the radiofrequency (RF) center frequency. To make a systematic evaluation of the estimator, we performed computer simulations of vessel wall motion, where pulse bandwidth, signal-to-noise ratio (SNR), signal-to-reverberation ratio, packet size and sample volume were varied. As reference, we also analyzed the conventional autocorrelation method and the cross-correlation method with parabolic interpolation. Under the simulation conditions considered here, the modified autocorrelation method had the lowest bias and variance of the estimators. When integrating velocity estimates over several cardiac cycles, the resulting tissue displacement curves might drift. This drift is directly related to the magnitude of the estimator bias and variance. Hence, the modified autocorrelation method should be the preferred choice of method.

Biophysical Phenomena↗
PubMed1996

Three-dimensional power Doppler imaging: a phantom study to quantify vessel stenosis.

This study investigated whether three-dimensional (3D) power Doppler imaging can be used to quantify arterial stenosis and its potential as an alternative to x-ray angiography. Three-dimensional power Doppler images of in vitro stenotic vessels were generated under different hemodynamic conditions with a 3D power Doppler imaging system. This system includes: a Macintosh Quadra 840AV computer used to perform 3D imaging acquisition, reconstruction and display; a computer-controlled motor-driven translation assembly used to move the transducer; and an ATL Ultramark 9 HDI ultrasound system. Three vascular- and tissue-mimicking phantoms containing three wall-less stenotic vessels with area reduction of 80%, 50% and 30% were imaged with different flow rates under both steady and pulsatile flow conditions and with different Doppler angles under steady flow condition. With the use of the blood mimic, experimental results demonstrated that power Doppler imaging is nearly independent on flow velocity and Doppler angle. It was also demonstrated that 3D power Doppler imaging can produce nonpulsatile angiographic-like 3D images of the flow field. The stenotic vessels were quantified with an overall accuracy of 8.3% of the vessel area and an overall precision of 7% of the vessel area under the conditions described in this paper. It is believed that 3D power Doppler imaging can be used to quantify arterial stenosis, and in some applications it could be an alternative to x-ray angiography.

Blood Flow Velocity↗
PubMed2002

Overexpression of semicarbazide sensitive amine oxidase in the cerebral blood vessels in patients with Alzheimer's disease and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

Semicarbazide sensitive amine oxidase (SSAO) metabolizes oxidative deamination of primary aromatic and aliphatic amines, and, in the brain, it is selectively expressed in blood vessels. SSAO expression is examined, by immunohistochemistry with a purified polyclonal antibody to SSAO from bovine lung, in the brains of subjects with Alzheimer disease (AD; n=10), cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL; n=2), and age-matched controls (n=8). SSAO immunoreactivity is restricted to meningeal and parenchymal blood vessels in control and diseased brains. Yet, a marked and selective increase in SSAO immunoreactivity occurs in association with betaA4 vascular amyloid deposits in patients with AD, and in the vicinity of the typical granular deposits in the blood vessels of gray and white matter in patients with CADASIL. Oxidative deamination of primary aromatic and aliphatic amines by SSAO produces ammonia, hydrogen peroxide and the corresponding aldehyde. Moreover, increased SSAO immunoreactivity is associated with increased Cu/Zn superoxide dismutase 1 expression restricted to abnormal blood vessels in diseased brains. Therefore, it is suggested that increased SSAO expression is a source of oxidative stress in the blood vessel wall in AD and CADASIL.

Aged↗