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At least 1,405 records · Page 78Linked to original sources
PubMed2001

Blood vessel maturation in a 3-dimensional spheroidal coculture model: direct contact with smooth muscle cells regulates endothelial cell quiescence and abrogates VEGF responsiveness.

Paracrine interactions between endothelial cells (EC) and mural cells act as critical regulators of vessel wall assembly, vessel maturation and define a plasticity window for vascular remodeling. The present study was aimed at studying blood vessel maturation processes in a novel 3-dimensional spheroidal coculture system of EC and smooth muscle cells (SMC). Coculture spheroids differentiate spontaneously in a calcium-dependent manner to organize into a core of SMC and a surface layer of EC, thus mimicking the physiological assembly of blood vessels with surface lining EC and underlying mural cells. Coculture of EC with SMC induces a mature, quiescent EC phenotype as evidenced by 1) a significant increase in the number of junctional complexes of the EC surface layer, 2) a down-regulation of PDGF-B expression by cocultured EC, and 3) an increased resistance of EC to undergo apoptosis. Furthermore, EC cocultured with SMC become refractory to stimulation with VEGF (lack of CD34 expression on VEGF stimulation; inability to form capillary-like sprouts in a VEGF-dependent manner in a 3-dimensional in gel angiogenesis assay). In contrast, costimulation with VEGF and Ang-2 induced sprouting angiogenesis originating from coculture spheroids consistent with a model of Ang-2-mediated vessel destabilization resulting in VEGF responsiveness. Ang-2 on its own was able to stimulate endothelial cells in the absence of Ang-1 producing SMC, inducing lateral sheet migration as well as in gel sprouting angiogenesis. Taken together, the data establish the spheroidal EC/SMC system as a powerful cell culture model to study paracrine interactions in the vessel wall and provide functional evidence for smooth muscle cell-mediated quiescence effects on endothelial cells.

Antigens, CD34↗
PubMed2003

Combined inhibition of VEGF and PDGF signaling enforces tumor vessel regression by interfering with pericyte-mediated endothelial cell survival mechanisms.

Destruction of existing tumor blood vessels may be achieved by targeting vascular endothelial growth factor (VEGF) signaling, which mediates not only endothelial cell proliferation but also endothelial cell survival. In this study, however, intravital microscopy failed to demonstrate that targeting of VEGFR-2 (by the tyrosine kinase inhibitor SU5416) induces significant regression of experimental tumor blood vessels. Immunohistochemistry, electron microscopy, expression analyses, and in situ hybridization provide evidence that this resistance of tumor blood vessels to VEGFR-2 targeting is conferred by pericytes that stabilize blood vessels and provide endothelial cell survival signals via the Ang-1/Tie2 pathway. In contrast, targeting VEGFR-2 plus the platelet-derived growth factor receptor (PDGFR)-beta system (PDGFR-beta) signaling (by SU6668) rapidly forced 40% of tumor blood vessels into regression, rendering these tumors hypoxic as shown by phosphorescence quenching. TUNEL staining, electron microscopy, and apoptosis blocking experiments suggest that VEGFR-2 plus PDGFR-beta targeting enforced tumor blood vessel regression by inducing endothelial cell apoptosis. We further show that this is achieved by an interference with pericyte-endothelial cell interaction. This study provides novel insights into the mechanisms of how 1) pericytes may provide escape strategies to anti-angiogenic therapies and 2) novel concepts that target not only endothelial cells but also pericyte-associated pathways involved in vascular stabilization and maturation exert potent anti-vascular effects.

Animals↗
PubMed2001

The effects of 30% and 60% xenon inhalation on pial vessel diameter and intracranial pressure in rabbits.

UNLABELLED: Xenon may increase cerebral blood flow and intracranial pressure (ICP). To evaluate the effects of xenon on brain circulation, we measured pial vessel diameter changes, CO(2) reactivity, and ICP during xenon inhalation in rabbits. Minimum alveolar anesthetic concentration (MAC) for xenon was established in rabbits (n = 6). By using a cranial window model, pial vessel diameters were measured at 30% and 60% xenon inhalation and in time control groups (n = 15). ICP, mean arterial blood pressure, and heart rate were recorded during 30% and 60% xenon inhalation (n = 5). Pial vessel diameters were measured during hypocapnia and hypercapnia conditions in 60% Xenon and Control groups (n = 14). MAC for xenon was 85%. Xenon (0.35 and 0.7 MAC) dilated the arterioles (10% and 18%, respectively) and venules (2% and 4%, respectively) (P < 0.05). Dilation of arterioles was more prominent than that of venules. ICP, mean arterial blood pressure, and heart rate did not change during xenon inhalation. No difference in CO(2) reactivity was observed between Xenon and Control groups (P = 0.79). Sixty percent xenon (0.7 MAC) dilated brain vessels, but venule changes were small. Xenon did not increase ICP and preserved CO(2) reactivity of the brain vessels. IMPLICATIONS: Xenon might increase cerebral blood flow; however, 0.7 minimum alveolar anesthetic concentration xenon preserved both low intracranial pressure and CO(2) reactivity of the cerebral vessels in the normal rabbit.

Administration, Inhalation↗
PubMed1999

Direct effects of alpha1- and alpha2-adrenergic agonists on spinal and cerebral pial vessels in dogs.

BACKGROUND: The effects of adrenergic agonists, often used as local anesthetic additives or spinal analgesics, on spinal vessels have not been firmly established. The authors investigated the effects of alpha2- and alpha1-adrenergic agonists on spinal and cerebral pial vessels in vivo. METHODS: Pentobarbital-anesthetized dogs (n = 28) were prepared for measurement of spinal pial-vessel diameter in a spinal-window preparation. The authors applied dexmedetomidine, clonidine, phenylephrine, or epinephrine in three different concentrations (0.5, 5.0, and 50 microg/ml; [2.1, 1.9, 2.5, and 2.3] x [10(-6), 10(-5), and 10(-4)] M, respectively) under the window (one drug in each dog) and measured spinal pial arteriolar and venular diameters in a sequential manner. To enable the comparison of their effects on cerebral vessels, the authors also administered these drugs under a cranial window. RESULTS: On topical administration, each drug constricted spinal pial arterioles in a concentration-dependent manner. Phenylephrine and epinephrine induced a significantly larger arteriolar constriction than dexmedetomidine or clonidine at 5 microg/ml (8%, 11%, 0%, and 1%, respectively). Spinal pial venules tended to be less constricted than arterioles. In cerebral arterioles, greater constrictions were induced by dexmedetomidine and clonidine than those induced by phenylephrine and epinephrine (14%, 8%, 0%, and 1%, respectively). Cerebral pial venules tended to exhibit larger constrictions than cerebral arterioles (unlike in spinal vessels). CONCLUSION: Dexmedetomidine and clonidine constricted spinal vessels in a concentration-dependent manner, but such vasoconstrictions were smaller than those induced by phenylephrine and epinephrine.

Adrenergic alpha-1 Receptor Agonists↗
PubMed1990

Washout of vessels with heparin does not improve patency following severe microarterial trauma: an experimental study.

The antithrombotic effect of heparin used as a wash-out solution in small arteries has been evaluated following severe vessel trauma (arteriotomy/intimectomy). Twenty-three central arteries of rabbit ears were prepared and platelets labeled with phosphorus-32 injected intraaortically. The arteries were positioned in double vascular clamps and opened by arteriotomy, and intimectomy was performed. After reestablishing blood flow, arteriotomic bleeding times, platelet accumulation in vivo, patency, and the amounts of intraluminal red thrombotic material were recorded. The rabbits were divided into two groups. In group A (12 vessels) the vessel interior was flushed with 2 ml of saline or Ringer's lactate solution. Group B (11 vessels) was similar except that the vessels were flushed with 2 ml of heparin, 100 IU/ml, in Ringer's lactate solution. In the control group (A) the bleeding time was 5 +/- 2 min, while in group B bleeding was so profuse that extra sutures had to be used in 6 of the vessels. Although significantly fewer platelets accumulated in heparin-treated animals, the patency frequencies and amounts of thrombotic material observed in both groups were similar. The final volume of thrombus formed is thus not always proportional to the degree of platelet accumulation. Washout of small traumatized arteries with heparin is thus not beneficial.

Animals↗
PubMed2001

Intraoperative evaluation of blood flow in the internal mammary or thoracodorsal artery as a recipient vessel for a free TRAM flap.

Although the free microvascular transverse rectus abdominis musculocutaneous (TRAM) flap is in routine use for breast reconstruction, little is known of its hemodynamics. The purpose of this study was to determine whether any differences exist when the free TRAM flap is anastomosed to the thoracodorsal or internal mammary vessels. The study comprised 25 patients receiving a free TRAM flap for breast reconstruction. The thoracodorsal vessels were used as recipients in 21 patients and the internal mammary vessels were used in 4 patients. Blood flow rate was measured directly in the donor and recipient arteries, and after anastomosis by a transit-time ultrasonic flowmeter (CardioMed). Two- and 3-mm probes were used. The blood flow rate in the donor artery (deep inferior epigastric) before flap dissection was 11 +/- 6 ml per minute (mean +/- standard deviation). The rate was significantly (p < 0.05) lower (5 +/- 3 ml per minute) in the recipient thoracodorsal artery than in the donor, but after transplantation it increased to 14 +/- 5 ml per minute (p < 0.05), attaining the same value as the donor artery. The blood flow rate in the intact internal mammary artery was significantly higher (25 +/- 10 ml per minute) than in the donor and thoracodorsal arteries, but after anastomosis it dropped to the same value (12 +/- 3 ml per minute; p < 0.05) as the donor artery. The intake of blood in TRAM flaps supplied by the intemal mammary artery seems to be no greater than that in free flaps anastomosed to thoracodorsal vessels, although the flow in the internal mammary artery was much higher. The authors concluded that the blood supply in a free TRAM flap is independent of the flow in the recipient artery and that thoracodorsal vessels, although often in a scarred bed and radiated, are as suitable for anastomosing a free TRAM flap as are internal mammary vessels.

Adult↗
PubMed1992

Recipient vessels for microvascular transplants in patients with hemifacial microsomia.

Hemifacial microsomia is a developmental abnormality involving structures derived from the first and second branchial arches. Microvascular transplants are increasingly being used to improve facial contour in patients with this condition. We have reviewed 9 patients with this abnormality to determine which recipient vessels have been used. In 6 patients, the facial vessels were located and used for flap revascularization. In 3 patients, the facial vessels could not be identified intraoperatively, and the occipital artery and a branch of the external jugular vein were used as recipient vessels. In this series of hemifacial microsomia patients, therefore, the facial vessels could not be located in 3 patients. We recommend that surgeons performing microsurgical transplants in cases of hemifacial microsomia be prepared to explore the external carotid and external jugular systems for recipient vessels.

Face↗
PubMed1998

Spatial distribution of diffuse, primitive, and classic amyloid-beta deposits and blood vessels in the upper laminae of the frontal cortex in Alzheimer disease.

The spatial distribution of the diffuse, primitive, and classic amyloid-beta deposits was studied in the upper laminae of the superior frontal gyrus in cases of sporadic Alzheimer disease (AD). Amyloid-beta-stained tissue was counterstained with collagen IV to determine whether the spatial distribution of the amyloid-beta deposits along the cortex was related to blood vessels. In all patients, amyloid-beta deposits and blood vessels were aggregated into distinct clusters and in many patients, the clusters were distributed with a regular periodicity along the cortex. The clusters of diffuse and primitive deposits did not coincide with the clusters of blood vessels in most patients. However, the clusters of classic amyloid-beta deposits coincided with those of the large diameter (>10 microm) blood vessels in all patients and with clusters of small-diameter (< 10 microm) blood vessels in four patients. The data suggest that, of the amyloid-beta subtypes, the clusters of classic amyloid-beta deposits appear to be the most closely related to blood vessels and especially to the larger-diameter, vertically penetrating arterioles in the upper cortical laminae.

Aged↗
PubMedDate not supplied

Blurring of vessels in spiral CT angiography: effects of collimation width, pitch, viewing plane, and windowing in maximum intensity projection.

PURPOSE: Our goal was to examine the effects of collimation width (CW), pitch, viewing plane, and windowing on the display of in-plane vessels in maximum intensity projection (MIP). METHOD: A theoretical concept based on partial volume averaging of vessels was developed to describe the contents of voxels (densities) in MIP and to derive cross-sectional vessel diameters and blurring. To validate the concept and to describe the influence of pitch, a Plexiglas cone submerged in water was scanned with varying CW and pitch. Binary MIP with three representative window levels was chosen so that definitive vessel diameters could be quantitated. RESULTS: The theoretical concept correctly predicted voxel contents and blurring for CW > or = 3 mm and low pitch. For high pitch, actual blurring was larger; however, for a given table speed, blurring of the cone decreased with pitch while increasing with CW. Overall blurring was most effectively reduced by using a thin CW and the transverse viewing plane. In the transverse viewing plane, the least blurring was found using binary MIP with a low window level. On the contrary, in the longitudinal viewing plane, blurring was minimized using a window level halfway between the density of the cone and that of the surrounding water. CONCLUSION: For CW > or = 3 mm, blurring of in-plane vessels can be explained with a simple geometrical concept based on partial volume. For accurate display, the transverse viewing plane should be used, a proper windowing must be chosen, and the CW should be kept below vessel size while raising the pitch to cover a reasonable volume.

Artifacts↗
PubMedDate not supplied

Depiction of intracranial vessels with MRA: utility of magnetization transfer saturation and gadolinium.

PURPOSE: The purpose of this work was to quantitate the individual and combined effects of magnetization transfer (MT) saturation and gadolinium (Gd) on the visualization of intracranial vessels with MR angiography (MRA). METHOD: Thirty-five subjects underwent two three-dimensional time-of-flight MRA sequences without and with MT and/or Gd. There were 14 MR angiograms without Gd or MT, 18 with MT only, 17 with Gd only, and 21 with both Gd and MT. On a projection image, a region of interest was drawn to delineate the arteries in the middle cerebral artery territory. The total area of blood vessels in the region of interest was calculated for each MR angiogram. Mean vessel areas for the four types of MRA were compared with analysis of variance. RESULTS: MRA with either MT or Gd alone showed significantly more vessel area than MRA without either (p < 0.05). MRA with MT alone and MRA with Gd alone were not different from each other (p = 0.29). The improvement in vessel area measured by using MT and Gd together was significantly more than expected from the cumulative improvement of adding each alone (p < 0.05). CONCLUSION: Combining MT and Gd synergistically improved the visualization of intracranial vessels on MRA.

Adult↗
PubMedDate not supplied

Interface vessels on color/power Doppler US and MRI: a clue to differentiate subserosal uterine myomas from extrauterine tumors.

PURPOSE: In subserosal myomas, vessels are often demonstrated between the masses and the uterus. This study was performed to assess the usefulness of demonstrating these vessels in differentiating subserosal myomas from extrauterine tumors on color or power Doppler US (CDUS/PDUS) and MRI. METHOD: This retrospective study included 41 patients with subserosal myomas and 27 patients with solid extrauterine tumors. The incidence and shape of these vessels seen on CDUS/PDUS and MRI were compared in the myoma and extrauterine tumor groups. RESULTS: The interface vessels were demonstrated in 39 of 41 subserosal myomas (18 on CDUS/PDUS, 14 on MRI, 7 on both), whereas they were seen in only 3 of 27 extrauterine tumors (1 on CDUS/PDUS, 2 on MRI). These three extrauterine tumors were ovarian malignancies that directly invaded the uterus. The shapes of these interface vessels were 7 intervening, 12 crossing, and 20 mixed in the myoma group, whereas they were mixed in all three extrauterine tumor groups. The sensitivity/specificity of this finding in differentiating subserosal myomas and extrauterine tumors was 100/92%, 91/91%, and 95/89%, respectively, with CDUS/PDUS, MRI, and either CDUS/PDUS or MRI. CONCLUSION: Observation of the interface vessels between the uterus and juxtauterine masses seems to be a useful clue in differentiating subserosal myomas from extrauterine tumors.

Adult↗
PubMed1990

Mapping of cavernous vessels in the liver in an autopsy case of hepatocellular carcinoma in comparison with imaging figures.

Cavernous vessels in the liver have been rarely described in the liver with hepatocellular carcinoma. We report the morphology and distribution of cavernous vessels in an autopsy liver of hepatocellular carcinoma, using a whole liver slice. In this case, antemortem angiography disclosed obstruction of portal veins at the hepatic hilus and portal trunk as well as many hepatopetal collaterals, mainly at the hepatic hilus. Tumor thrombi were diffusely distributed in the liver from the portal trunk to peripheral portal branches at autopsy. The cavernous vessels, which were positive for Factor VIII-related antigen, were also distributed throughout the liver from the hepatic hilus to the subcapsular regions, especially around the occluded portal veins by hepatocellular carcinoma, suggesting that these vessels were collaterals that developed as the result of portal obstruction. This study suggests that these vessels might be present from the hepatic hilus to the subcapsular regions, even if antemortem imaging techniques disclose collateral vessels only at the hepatic hilus.

Autopsy↗
PubMed2001

Vasodilatation, not hypotension, improves resistance vessel design during treatment of essential hypertension: a literature survey.

Correction of structural abnormalities in resistance arteries of patients with essential hypertension is a potential treatment goal, in addition to blood pressure reduction. However, available evidence from human as well as from animal studies indicates that antihypertensive therapy is not always accompanied by normalization of resistance vessel structure, despite normalization of blood pressure. Thus, blood pressure is not the only factor determining resistance vessel structure, and experimental studies show that several factors could play a role, including shear stress and hormonal stimulation. To date, there has been no systematic review of the many published papers which have studied the structural effects of antihypertensive therapy, and it is not known which conditions are best able to normalize resistance vessel structure. We have therefore made a survey of the available literature. The survey shows that change in blood pressure in indeed a poor indicator of change in resistance vessel structure. However, it is a remarkably consistent finding that normalization of resistance vessel structure is obtained with therapeutic regimens which reduce blood pressure by vasodilation rather than by lowering cardiac output Thus, to the extent that normalization of resistance vessel structure is deemed a goal of antihypertensive treatment, the survey points towards the importance of considering not only the treatment effect on blood pressure, but also the haemodynamic effects within patients with essential hypertension.

Antihypertensive Agents↗
PubMed1991

Transperineurial vessel constriction in an edematous neuropathy.

The hypothesis that the accumulation of endoneurial edema can exert forces sufficient to occlude transperineurial vessels was tested using light microscopy and computer-assisted morphometry in rat sciatic nerve. Experimental nerves were exposed to a concentration of 10% procaine HCl, which from previous studies has been demonstrated to routinely produce an edematous neuropathy. For each vessel, a "constriction ratio" was defined by dividing its minimum intraperineurial lumen area by the average for minimum endoneurial and epineurial lumen cross-sectional areas. Constriction ratios were 0.91 +/- 0.26 (mean +/- SD) for control vessels and 0.28 +/- 0.25 for vessels in the procaine group (p less than 0.005). In addition, a strong negative correlation was observed between the morphologic demonstration of nerve edema and the transperineurial vessel constriction ratio (r = -0.85; p less than 0.002). It is concluded that in neuropathies characterized by widespread edema and increased endoneurial fluid pressures, the concomitant constriction of transperineurial vessels could diminish nerve blood flow and facilitate nerve injury.

Animals↗
PubMed1989

Prostaglandin E1 and nitroglycerin effects on canine epicardial conductance and distal coronary resistance vessels.

Prostaglandin E1 (PGE1) has been reported to be a coronary vasodilator and has been considered clinically in the treatment of coronary vasospasm, but its mechanism of action is not known. To evaluate the vasomotor effect of PGE1, epicardial coronary and distal resistance vessel responses were compared by PGE1 and nitroglycerin infusion into the left anterior descending (LAD) artery of the closed-chest dog. Coronary angiography and 133Xe washout flow measurements were used to quantitate proximal and distal vessel responses, respectively. To evaluate potential inhibitory actions, vessels were contracted by continuous LAD infusion of prostaglandin F2 alpha (PGF2 alpha) or serotonin before dose-response testing with PGE1 or nitroglycerin. PGE1 alone produced a 20% dilation of the LAD in vivo but only with the highest dose (2.0 micrograms/min). PGE1, however, did not reverse epicardial vessel constriction induced by PGF2 alpha or serotonin. LAD flows (resistance vessel response) were increased comparably by PGE1 alone and with PGF2 alpha added (100 and 93% above control flow, respectively) but to a lesser extent with serotonin added (57% above control). In contrast, nitroglycerin completely reversed epicardial artery constrictions induced by PGF2 alpha and serotonin. Our findings indicate that although PGE1 is a vasodilator in vivo, it does not demonstrate a major effect in dilating epicardial conductance coronary arteries and therefore may not be beneficial in antagonizing endogenous contractile factors in treatment of coronary vasospasm. PGE1 does increase coronary blood flow by dilating distal resistance vessels. The beneficial effects of PGE1 in humans with unstable angina therefore are probably not due to vasorelaxing effects on epicardial coronary conductance arteries.

Alprostadil↗
PubMed1993

[125I]-endothelin-1 binding to vasa vasorum and regions of neovascularization in human and porcine blood vessels: a possible role for endothelin in intimal hyperplasia and atherosclerosis.

The distribution of [125I]-endothelin-1 (ET-1) binding sites on human and porcine vessels was studied with in vitro receptor autoradiography. Binding to normal human saphenous veins was compared to atheromatous veins used as coronary artery bypass grafts. Binding to porcine vessels, from an experimental model of intimal hyperplasia, was also studied. There was dense binding of [125I]-ET-1 to smooth muscle of all vessels examined, as well as to the vasa vasorum and regions of neovascularization of diseased vessels. Binding to microvasculature (vasa vasorum and regions of neovascularization) is of particular interest, because ET-1 has been shown to have mitogenic activity on vascular smooth-muscle cells in culture and microvessels are extremely sensitive to the constrictor effect of ET-1. Binding of [125I]-ET-1 to vasa vasorum of normal blood vessels and to regions of neovascularization of atheromatous vessels suggests that ET-1 plays a pathophysiologic role in atherosclerosis.

Animals↗
PubMed2001

Retroperitoneoscopic pyelotomy combined with the transposition of crossing vessels for ureteropelvic junction obstruction.

PURPOSE: We developed a new approach of retroperitoneoscopic pyelotomy combined with the transposition of crossing vessels for ureteropelvic junction obstruction as an alternative to conventional antegrade or retrograde endopyelotomy. MATERIALS AND METHODS: From February 1997 to August 1999 we treated 5 cases of ureteropelvic junction obstruction due to crossing vessels that were diagnosed by helical computerized tomography. Ureterovascular hydronephrosis characterized by a malrotated renal pelvis with anterior crossing vessels was observed in 4 cases and ureteropelvic junction obstruction with a posterior crossing artery was present in 1. After endoureterotomy stent insertion under cystoscopic guidance we performed retroperitoneoscopic endopyelotomy with the kidney in standard position. Crossing vessels were transposed to a higher position to remove obstruction and fixed with peripelvic tissue via retroperitoneoscopy. In all cases a longitudinal incision approximately 1.5 cm. long was made with a potassium titanyl phosphate laser. RESULTS: Convalescence was uneventful in all patients and the endoureterotomy stent was removed 4 to 8 weeks after surgery. Postoperatively helical computerized tomography showed the successful transposition of crossing vessels and significant hydronephrosis resolution in all cases. All patients were asymptomatic during followup of 17 to 28 months. CONCLUSIONS: Despite our small number of patients our results are sufficient to conclude that retroperitoneoscopic pyelotomy combined with the transposition of crossing vessels is a simple and reliable method for treating ureterovascular hydronephrosis and associated conditions.

Adult↗
PubMed1990

A study of the reactivity of feeding vessels to arteriovenous malformations: correlation with clinical outcome.

Isolated segments from the feeding arteries to arteriovenous malformations (AVMs) from 24 patients were studied in vitro. In a perfusion chamber, isometric contraction of these arterial rings to various vasoactive substances was recorded and correlated with the following: spontaneous activity, spasm as seen in the operating room; radiographic evidence of ectasia preoperatively and postoperatively; and postoperative course. Of the 24 patients studied, four patients had nonreactive AVM nutrient vessels upon in vitro testing. In addition, these vessel segments displayed no spontaneous activity although all of the other vessels tested developed spontaneous activity while in the perfusion chamber. The patients with "unreactive vessels" had an increased incidence of postoperative edema and hemorrhage in the surrounding brain, consistent with the symptoms of normal perfusion pressure breakthrough. Thus, our study utilizes an in vitro technique to evaluate a specific segment of the AVM complex, the feeding vessel, which permitted us to assess abnormalities of reactivity in these vessel segments. This method may be useful for future evaluations of the pathophysiology of AVMs.

Animals↗