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At least 1,297 records · Page 72Linked to original sources
PubMed2001

Detection of lipoprotein(a) in intraparenchymal cerebral vessels: correlation with vascular pathology and clinical history.

Serum levels of lipoprotein(a), Lp(a), have been shown to be associated with increased risk of atherosclerosis (AS) and AS-related diseases such as myocardial and ischemic cerebral infarcts (ICI). Lp(a) has been detected in the vascular wall of the aorta and coronary vessels, and we documented the presence of apo(a) in cerebral vessels of the Circle of Willis, associated with AS changes. In this study we further investigated and characterized the biochemical nature of Lp(a) detected in both large and small cerebral parenchymal vessels. Autopsy specimens of cerebral vessels of 51 patients were examined by immunohistochemistry with monoclonal antibodies against apo(a), apoB, and plasminogen. Lp(a) was detected in cerebral capillaries and arterioles. All of the 8 patients with ICI expressed Lp(a) in parenchymal vessels, generally (6/8) in both capillaries and arterioles. Of 43 patients without ICI only 25 had Lp(a) detected. Among the patients without ICI, there was a slightly increased incidence of parenchymal Lp(a) in those patients who had severe hypoxic brain damage (12/20) compared to those patients without severe hypoxic damage (9/23). Thus, the presence of Lp(a) in small cerebral parenchymal vessels may reflect the role of Lp(a) in ICI.

Adult↗
PubMed1996

Chemical induction of fenestrae in vessels of the blood-brain barrier.

The endothelium responsible for the blood-brain barrier to hydrophilic solutes has been converted here, by chemical means, to the fenestrated, permeable type of vessel (FV). During development, some brain vessels are reported to be transiently fenestrated. Endothelial fenestrae of adrenal glands are known to be reinduced in vitro by retinoic acid (RA) or phorbol myristate acetate (PMA). Could fenestrae be likewise reinduced in brain barrier vessels? When RA or PMA were infused continuously by an osmotic pump for 28 days into the cerebral cortex of rats, some brain vessels in the lesion cavity created by the reagents were FV. There were no FV in adjacent brain. When 100 microM RA was infused, about 20% of vessels in the cyst were FV, as were about 29% after infusion of 150 ng/ml PMA. Fenestra development depended on concentration and time. Reversibility of fenestra formation was complete at 1-2 months after delivery of RA or PMA had ceased. It is proposed that the RA and PMA effect is mediated by the plasminogen activator urokinase, in as much as both RA and PMA stimulate its production. This notion is supported by preliminary experiments in which urokinase infusion into brain also produced fenestrae. It is further suggested that the reversible induction of fenestrae in the mature brain by RA, PMA, and, perhaps, a variety of other conversion factors may be confined to a subset of brain barrier vessels that must be regenerating and of the kind that were temporarily fenestrated during fetal life.

Animals↗
PubMed1999

The lymphatic vessels and the so-called "lymphatic stomata" of the diaphragm: a morphologic ultrastructural and three-dimensional study.

We studied the absorbing peripheral lymphatic vessel with the light microscope, the transmission electron microscope, the scanning electron microscope, and three-dimensional models of the diaphragm of several rodents and insectivores under normal and experimental conditions (lymphatic stasis and dehydration). To clarify the delicate and complex mechanism that permits drainage of the abdominal cavity contents into the lymphatic circulatory system, we introduced Polystyrene latex spherules, China ink, and Trypan blue into the abdominal cavities. After anatomical comparisons of the superficial and deep networks of absorbing peripheral lymphatic vessels at the tendinous and muscular portions of the diaphragm and after classification of lymphatic vessels into absorbing and conducting functions, we examined the stomata, which, owing to morphologic and topographic findings, we defined as stable structures. Furthermore, we observed that the stomata and submesothelial connective channel are fundamental elements that facilitate the flow of the corpuscular and liquid contents of the peritoneal cavity to the submesothelial absorbing lymphatic vessel wall. Also, we underlined that the genesis of the connective channel depends on the secondary cytoplasm extensions of two distinct adjacent endothelial cells, which, to facilitate the flow of the absorbed abdominal contents, completely coat this channel. Additionally, our observations illustrate that the secondary cytoplasm extensions do not engage in continuous relationships with the basal lamina of the mesothelium and with the margins of the stoma, and, hence, the hypothesis of "lymphatic stomata" as an expression of the anchoring of the borders of the open interendothelial junctions to the orifice margins of the stoma cannot be confirmed. Moreover, we describe the presence and formation of intraendothelial channels in the lymphatic endothelial wall. We affirm that this morphological entity is a dynamic unit, because its numerical density varies according to different physiological and experimental conditions to degrees of hydrostatic and colloidal osmotic pressure and, perhaps, also to the particular characteristics of the substances that the connective channel liberates into the endothelial wall of the lymphatic vessel. In conclusion, we affirm that the absorbing peripheral lymphatic vessels of the diaphragm, by way of intraendothelial channel formations, membrane diffusion, and the vesicular path of the endothelial cells, constitute the fundamental draining elements for the corpuscular and liquid contents of the abdominal cavity.

Absorption↗
PubMed2000

Different pathways of macromolecule extravasation from hyperpermeable tumor vessels.

Tumor microvessels are hyperpermeable to plasma proteins, a consequence of tumor cell-secreted vascular permeability factor/vascular endothelial growth factor (VPF/VEGF). However, the pathways by which macromolecules extravasate from tumor vessels have been little investigated. To characterize tumor vessels more precisely and to elucidate the pathways by which macromolecules extravasated from them, we studied two well-defined, VPF/VEGF-secreting murine carcinomas, MOT and TA3/St. Whether grown in ascites or solid form, MOT tumors induced large, pericyte-poor "mother" vessels whose lining endothelium developed fenestrae that involved 1.8-5.6% of the surface. Fenestrae developed in parallel with markedly reduced endothelial cell vesiculo-vacuolar organelles (VVOs). TA3/St tumors, which secreted more VPF/VEGF than MOT tumors, elicited mother vessels with unchanged VVOs and without fenestrae. In both tumors, a plasma protein tracer, ferritin, extravasated through VVOs and in MOT tumors ferritin also extravasated through fenestrae. Endothelial gaps were not observed in either tumor. Thus, not all VPF/VEGF-secreting tumors induce fenestrated endothelium. Also, VVOs provide an internal store of membrane that can be transferred to the endothelial cell surface to provide the substantial increase in plasma membrane necessary for mother vessel formation in MOT tumors. Such transfer was apparently unnecessary in TA3/St tumors in which extensive early endothelial cell division provided the increased plasma membrane necessary for forming mother vessels.

Animals↗
PubMed2002

How a highly complex three-dimensional network of blood vessels regresses: the gill blood vascular system of tadpoles of Xenopus during metamorphosis. A SEM study on microvascular corrosion casts.

The morphology and vasculature of filter plates and filter rows of tadpoles of Xenopus laevis Daudin were studied from prometamorphosis (stage 56) to metamorphic climax (stage 62) by scanning electron microscopy (SEM) of (i) critical point-dried specimens and (ii) microvascular corrosion casts. The number and frequencies of the highest branching orders of venous filter row vessels, which reach their maximum (6) in stage 58, as well as vessel diameters, interbranching distances, and branching angles were measured. Branching orders continuously decrease until stage 62, so that only two are left. Vessel (luminal) diameters increased from 16.9 +/- 0.65 microm (SEM) (stage 56) to 19.3 +/- 0.61 microm (stage 58) (branching order 0) and then decreased to 16.7 +/- 0.91 microm (stage 62). Interbranching distances were largest in stage 59 (57.5 +/- 2.07 microm (branching order 0). Branching angles were highest in stage 62 (91.4 degrees +/- 8.82 degrees; branching order 2) and lowest in stage 56 (76.0 degrees +/- 4.64 degrees; branching order 4). From the morphology of cast vessels we conclude that vascular regression is organized by progressive "fusion" of opposite vessels in the highest branching orders ("miniaturization") until only a single capillary loop connects the terminal arteriole and the main filter fold venule. With obliteration of the single capillary loop, the regression of the gill vasculature is terminated. It is noted that the "fusion" of gill vessels is reminiscent of "reversed" intussusceptive microvascular growth.

Animals↗
PubMed1996

Distribution of [3H] alpha, beta-methylene ATP binding sites in pulmonary blood vessels of different species.

Purinergic neurotransmission has been reported to take part in the regulation of pulmonary vascular resistance in many species. The receptor which mediates the contraction of blood vessels by ATP was defined as P2X-purinoceptors in pharmacological studies. In the present study, autoradiographic localization of P2X-purinoceptors was carried out in pulmonary blood vessels from rat, guinea-pig, rabbit, piglet and human by using [3H] alpha, beta-methylene ATP ([3H] alpha, beta-MeATP) as the radioligand. Autoradiographs showed that all the pulmonary arteries had been labelled with [3H] alpha, beta-MeATP. The specific binding sites were only associated with the smooth muscle of the blood vessels. Semi-quantitation of the autoradiographs revealed significant differences in the densities of P2X-purinoceptors amongst the vessels studied, both regional and interspecific. Generally, intrapulmonary arteries were labelled more heavily than the main pulmonary arteries, and the medium- and small-sized arteries had higher densities of P2X-purinoceptor than the large muscular arteries. The veins were sparsely labelled, except that rat intrapulmonary veins were labelled moderately. The results from this study provide: (1) direct evidence for the existence of P2X-purinoceptors in pulmonary vasculature, (2) a semi-quantitative estimation of the relative density of P2X-purinoceptors in pulmonary vessels of different sizes; and (3) a comparison of the P2X-purinoceptor densities among the species studied. Furthermore, the distribution of the P2X-purinoceptors is consistent with known pharmacological responses elicited by ATP in these vessels.

Adenosine Triphosphate↗
PubMed1993

Histochemical demonstration of mucin in lymphatic vessels of human middle ear cholesteatoma.

We investigated the possible existence of mucin in lymphatic vessels in cholesteatoma perimatrix using the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method. Histochemical staining distinguished two types of lymphatic vessels, one of which contained PA-TCH-SP reacting substance showing a loose mesh-like appearance. Connective tissue was edematous around this vessel and was infiltrated by abundant round cells. The second type of lymphatic vessel did not contain PA-TCH-SP reacting substance and few round cells were seen infiltrating tissue around this vessel. Gland-like structures of mucous epithelium in the perimatrix were heavily stained by the PA-TCH-SP method. Secretory granules of the mucous epithelium and its luminal content had a loose mesh-like appearance. Since contents of the gland-like structures may leak through the chinks of epithelial cells into subepidermal connective tissues, the resultant inflow of mucin into the lymphatic vessels may then cause inflammation of the cholesteatoma perimatrix.

Cell Nucleus↗
PubMed1993

Spontaneous hemopneumothorax with aberrant vessels found to be the source of bleeding: report of two cases.

We report herein our experience of two cases of spontaneous hemopneumothorax in which the source of bleeding was found to be aberrant vessels. Both patients were successfully treated by early thoracotomy. Case 1 was a 23-year-old female in whom chest X-ray revealed an air-fluid line and a bulla with a narrow restiform shadow connecting the pleural cupola. Angiography clearly visualized aberrant vessels branching from the costocervical trunk, distributed in and around the bulla in the apex of the lung, being the possible source of bleeding. These aberrant vessels were confirmed at surgery and resected. Case 2 was a 56-year-old male who underwent thoracotomy for persistent bleeding. At surgery, a continuously bleeding vessel from the pleural cupola was seen and ligated. The remnant of the vessel was located in the apex of the lung, and resected with the bulla. Thus, the rare entity of a congenital aberrant vessel lying concealed as a possible source of bleeding should be borne in mind.

Adult↗
PubMed1988

Altered expression of collagen type VI in brain vessels of patients with chronic hypertension. A comparison with the distribution of collagen IV and procollagen III.

The vascular extracellular matrix (ECM) plays an important role in the histopathology of cerebral microcirculation, but its characterization is still incomplete. For that reason we investigated paraffin-embedded and cryostat sections of intracerebral and meningeal vessels from eight normotensive and six hypertensive humans using monospecific affinity-purified polyclonal antibodies against human/monkey amino-terminal procollagen I + III peptide (P I P, P III P), collagen IV (7-S and NC1 domains), VI, and laminin (P 1 fragment) by applying peroxidase-antiperoxidase- and alkaline phosphatase-antialkaline phosphatase techniques. In normotensives, laminin and collagen IV were codistributed in the basal lamina of meningeal and intraparenchymal vessels. Collagen VI was only present in the adventitia of meningeal vessels and larger intraparenchymal arteries and veins, whereas it was absent from cortical vessels including capillaries. Intensive staining for collagen VI was observed in the choroid plexus, the superficial glia and sheath of cranial nerves. In hypertensives, the basement membrane constituents laminin and collagen IV appeared ubiquitously increased. Here, collagen VI was also deposited in the broadened vascular intima and media of larger arteries and in cortical vessels. In both groups collagen VI and P III P appeared to be codistributed. Our results indicate that significant qualitative change sin ECM of cerebral blood vessels are taking place during the development of hypertension, such as (1) an atypical deposition or an increase of collagen VI which by interconnecting collagen fibrils (I and III) might exert a stabilizing (sclerosing) function in the ECM, and (2) a thickening of vascular basement membranes caused by an accumulation of its major components laminin and collagen IV.

Aged↗
PubMed1995

Active and passive reaction of large arterial vessels to sublingual test with nitroglycerin.

The noninvasive method of oscillovasometry, devised previously, was applied to the estimation of arterial pressure, effective radius of large arterial vessels, a number of indices showing elastic vessel properties and change in tone of the vessels on the right upper limb just before sublingual administration of nitroglycerin (0.5 mg) to the patients and 4-5 min after it. A group of 96 patients with different levels of arterial pressure were examined. It was found that all the patients showed a pressure decrease and tachycardia, but about a half of them had a passive response in large arterial vessels in the form of a decrease in the vessel volume, while others showed a decrease in arterial vessel tone (vasodilation), i.e. an active vascular response. From the data we drew the conclusion that there are two types of vascular response (active and passive) and they do not depend on the initial level of arterial pressure. Nitroglycerin probably acts more effectively on large arteries with a high initial tone. The possible mechanism of this phenomenon is discussed.

Administration, Sublingual↗
PubMed1988

[The surgical anatomy of the rectal and anal blood vessels].

The authors examined 40 rectum specimens by angiography, preparation and staining methods to show the exact arterial vessel supply of the rectum and tried to find out whether a reason could be found for the relatively high rate of suture leaks after low resection of the rectum or not. The insertion of the levator muscle is a sort of vessel divide: caudal to the levator muscle the inferior rectal artery is the main supplying vessel, cranially the superior rectal artery. Here a vessel deficient-area always remains in the dorso-caudal sector of the rectal ampulla which cannot be compensated by another rectum-supplying vessel. The middle rectal artery supplies the rectum accessorily. The results are able to explain why the suture leaks are constantly observed in the dorso-caudal ampulla after profound anterior resection of the rectum. Furthermore the results account for the good healing tendency of coloanal anastomoses: the inferior rectal artery amply supplies the anal canal; there is not the same vessel-deficient area as found cranial to the levator muscle.

Anal Canal↗
PubMed1978

The action of sodium nitroprusside on the pial vessels.

This study in cats investigates the action of sodium nitroprusside on the pial vessels by systemic and local administration, with an intravital microscopic window technique and a photometric technique for graphic documentation of vessel diameter changes. Intravenous infusion caused vasodilatation parallel with decreasing blood pressure. Pial arterioles dilated more than venules, smaller vessels more than larger ones. Local administration caused maximal dilatation within 5--10 seconds. With blood pressure returning to normal after i.v. therapy, pial vessels remained wider than they were before hypotension at the same pressure level. From these data it is concluded that the substance acts longer on the brain vessels than on vessels elsewhere in the body, and that cerebrovascular autoregulation to blood pressure changes is disturbed during this period.

Animals↗
PubMed2004

Method for modelling cerebral blood vessels and their bifurcations using circular, homogeneous, generalised cylinders.

A method for automatic modelling of blood vessels and their bifurcations from 3D scans of the brain is presented. The method is a three-step procedure. First, a skeleton of the cerebral blood vessels is developed, and then the surfaces of the blood vessels are located using an active contour approach. The active contour approach uses circular homogeneous generalised cylinders (CHGCs) to model the thin, elongated blood vessels. Finally, a novel method for modelling the surfaces of the bifurcations in a vessel tree is presented. The method was tested on simulated data: a computed tomography angiography (CTA) and four magnetic resonance angiography (MRA) volumes. Furthermore, the method was tested on ten magnetic resonance images (MRIs) to demonstrate its robustness. The test on the simulated data indicated that the approach for the surface modelling of vessels had a mean radius error of less than 0.1 mm and a mean localisation error of 0.1 mm. Surface models evaluated by an expert in vascular neurosurgery were found to have a smooth appearance and generally agreed with the image data. The test on the MRI scans indicated that the method performed well in noisy environments.

Brain↗
PubMed2005

Sprouting from arteriovenous shunt vessels with increased blood flow.

The purpose of this study was to evaluate the effect of increased blood flow on angiogenesis at the large vessels. The arteriovenous (AV) shunt was made on the thigh of male Wistar rats (n = 27) to increase blood flow, wrapped with artificial skin dermis, which consisted of a silicon outer layer, and isolated from surrounding tissues. Blood flow increased from 2.40 +/- 0.77 to 35.8 +/- 8.7 ml min(-1) (14.9 times), and the shear stress index (relative value of shear stress) increased from 10.7 +/- 3.6 to 73.4 +/- 18.1 (6.85 times) 60 min after the shunt formation. Newly formed vessels were observed around the AV shunt loop. Scanning electron micrographs at the AV shunt vessel lumen showed modified endothelial cells at day 7 and a remarkable number of pores at day 14. The volume of newly formed vessels was increased 12 times from day 5 to day 14. The mechanical factor of shear stress was considered the major stimulator of angiogenesis. This is the first report of electron-microscopic observation of sprouts from a large vessel lumen. The new AV shunt model is useful for basic research on angiogenesis at the large vessels in vivo and, furthermore, could generate vascularised tissues with various cultured cells.

Animals↗
PubMed2003

[Laparoscopic living donor nephrectomy of kidneys with multiple renal vessels].

Due to the increasing waiting time for transplantation of a cadaveric kidney, living donor kidney transplantation is an increasingly oncoming issue. Laparoscopic donor nephrectomies (LDN) have been performed since 1995 and presently more than 100 transplant centers offer this minimally invasive surgical approach. The advantages for the donor of less pain, shorter hospital stay, earlier return to work, better cosmetic results in combination with an organ function equal to open donor nephrectomy are the reasons for an enormous increase in LDN. Since up to 30% of the donor kidneys have multiple vessels for blood supply, an increase of these organs for LDN can be expected. We performed a retrospective study of LDN at our center and compared donors with multiple vs single vessel supply. From February 1999 to September 2002, 63 LDN were performed at the department of Urology, Charité University Hospital, Berlin. A comparison between 18 donor kidneys with multiple vessel supply and 45 donor organs with single vessels showed no difference for the time of laparoscopic explantation (207 vs 201 min, p=0.4) or the warm (166 vs 148 s, p=0.2) and cold ischemic times (117 vs 103 min, p=0.66). As could be expected, the mixed ischemic time, i.e., the time for anastomosis of the kidney with the recipient's vessels, showed a significant difference (53 vs 46 min, p=0.02). Intra- and postoperative complication rates for donors and recipients were not different in both groups. Laparoscopic donor nephrectomy for kidneys with multiple vessels is feasible and safe for donor and recipient.

Adult↗
PubMed1999

Functional effects of 4-aminopyridine (4-AP) on pulmonary and systemic vessels from normoxic control and hypoxic pulmonary hypertensive rats.

The effects of the outward rectifying potassium channel blocker, 4-aminopyridine, on contractile tone and on contractile responses to the spasmogens, 5-hydroxytryptamine and endothelin-1, were examined in pulmonary arteries (main and intralobar) and systemic vessels (aorta and mesenteric artery) from rats with and without hypoxic pulmonary hypertension. Hypoxic pulmonary hypertension was induced by exposure of rats to 10% oxygen for 1 week. The development of pulmonary hypertension was associated with (i) depolarization of the cell membrane in intralobar pulmonary artery, but not aorta, and (ii) an increase in sensitivity to 5-hydroxytryptamine in pulmonary, but not systemic, vessels; sensitivity to endothelin-1 was unchanged. 4-Aminopyridine contracted all of the vessels studied. In pulmonary hypertension the sensitivity to 4-aminopyridine was increased ten-fold in pulmonary vessels but was unchanged in systemic vessels. Threshold concentrations of 4-aminopyridine (< or =3x10(-3) M) augmented contractions to 5-hydroxytryptamine in main pulmonary artery and aorta from control rats but failed to augment contractions to 5-hydroxytryptamine in main pulmonary artery from pulmonary hypertensive rats. Responses to endothelin-1 were not augmented by 4-aminopyridine. The membrane depolarization and the increases in sensitivity to 4-aminopyridine and 5-hydroxytryptamine seen in pulmonary hypertension are compatible with the concept that potassium channel function is altered in pulmonary, but not systemic, vessels from pulmonary hypertensive rats. Our data suggest that in main pulmonary artery a common mechanism is responsible for (i) the augmentation of 5-hydroxytryptamine responses by 4-aminopyridine in control rats, and (ii) the sensitization to 5-hydroxytryptamine seen in pulmonary hypertensive, compared with control, rats in the absence of 4-aminopyridine. Hence, we conclude that the sensitization to 5-hydroxytryptamine may be due to downregulation of 4-aminopyridine-sensitive potassium channels.

4-Aminopyridine↗
PubMed2001

Dural congestion accompanying meningioma invasion into vessels: the dural tail sign.

Our purpose was to verify the histological appearance of the dural tail accompanying meningiomas on MRI. We studied seven patients such a dural tale. We examined the point of attachment of the tumour and the adjacent dura mater histologically. In all patients, rich vascularity and dilated vessels were observed in the dura mater at the point of attachment of the tumour; tumour cells invaded the dura mater and vessels, packing the latter. In the adjacent dura mater, showing as a dural tail on MRI, there was tumour-cell invasion in only one patient. Vascular congestion around the vessels compacted by the tumour cells in the dura mater and dilated vessels were seen in all patients. We therefore suggest that the mechanism of the dural tail sign is as follows. First, tumour cells invade vessels and pack them at the point of tumour attachment. Then, vessel congestion is induced in the adjacent dura mater, as a result of which it enhances markedly, giving rise to the dural tail sign.

Adult↗
PubMed2002

Effect of vessel size on the flow efficiency of the total cavopulmonary connection: in vitro studies.

The total cavopulmonary connection (TCPC) creates a passive system of blood flow into the pulmonary circulation. We hypothesize that the efficiency differences found in models with superior vena cava-inferior vena cava (SVC-IVC) offsets is dependent on vessel size, with flow efficiency improving with larger size vessels. Two sets of in vitro TCPC models (TCPC-3 and TCPC-15) were constructed corresponding to average vessel diameters of 3- and 15-year-old patients. The model with full SVC-IVC offset was the most efficient in TCPC-3 models. There was no significant difference between geometric arrangements in TCPC-15 models; however, the average efficiencies were significantly higher. Among the models representing vessel sizes of the younger age group, the model with the full-diameter SVC-IVC offset was the most efficient. The models representing vessel sizes of the older age group showed marked improvement in efficiencies throughout without obvious differences between various geometric arrangements. This suggests that geometric considerations in TCPC surgical techniques may be of lower than expected significance over the life span of a patient. More important, after balancing the effects of improved flow efficiency with larger vessels against the effects of chronic volume overload, the trend of performing the Fontan surgery on increasingly younger patients may need to be reconsidered after further studies.

Adolescent↗