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At least 1,801 records · Page 100Linked to original sources
PubMed1993

Establishment of heterogeneity among blood vessels: hormone-influenced appearance of hepatic lipase in specific subsets of the ovarian microvasculature.

We used biochemical and structural approaches to analyze the influence of gonadotropic hormones on the association of hepatic lipase with specific subsets of ovarian blood vessels. Western blotting was used to detect this enzyme in effluent collected from heparin-perfused ovaries of nonhormone-treated immature rats and those primed with pregnant mare's serum gonadotropin (PMSG) alone or in combination with human chorionic gonadotropin (hCG). The effects of these hormones on hepatic lipase distribution among ovarian blood vessels was assessed before and after hCG and/or PMSG treatment by immunofluorescence and immunogold cytochemistry. For the latter, immunoreagents and fixative were delivered directly to chilled, unfixed ovaries by in situ vascular perfusion. Data from biochemical and structural analyses indicated that hepatic lipase was absent from nonhormone-treated ovaries. As shown by Western blotting of ovarian effluent, the enzyme appeared following treatment with PMSG and PMSG-hCG; it increased in amount in a time-dependent manner, with a transient decline in the early hours after hCG injection. Enzyme levels paralleled growth and vascularization of follicles and corpora lutea; the fall tended to coincide with early events in luteal angiogenesis. Immunogold microscopy showed that hepatic lipase was abundant in thin-walled blood vessels of theca interna of follicles, corpora lutea, and interstitial cells but sparse in those of the stroma. Moreover, during neovascularization of differentiating corpora lutea, vascular sprouts arising from hepatic lipase-laden thecal vessels appeared to lose, then regain, the enzyme as development progressed. Our findings thus suggest 1) that hormones influence the establishment of endothelial cell heterogeneity within the microvasculature of a single organ and 2) that development of novel endothelial cell properties in specific subsets of blood vessels underlies compartmentalization of function within a tissue.

Animals↗
PubMed1994

Neoformation of blood vessels in association with rat lung fibrosis induced by bleomycin.

We have used intratracheal instillation of bleomycin in rats to study the microanatomical changes of blood vessels associated with lung fibrosis. Bleomycin is a toxic cytostatic drug employed in classical models of lung fibrosis. Wistar rats were submitted to intratracheal injection of 1.5 units of bleomycin and sacrificed 2.5 months later, a timing when marked fibrosis of the lung is observed. We casted the vascular tree of the rat lungs by perfusion with a methacrylate resin. These casts were studied by scanning electron microscopy. Lung tissue was also studied by light microscopy and thin section electron microscopy. The major vascular modifications observed in the bleomycin-treated rats were: (1) neoformation of an elaborate network of vessels located in the peribronchial domains of the lung, and (2) distortion of the architecture of alveolar capillaries. By light microscopy, it was clear that the newly formed vascular network was located in regions of fibrosis (which in the resin casts were digested away). These neoformed vessels appeared to originate from bronchial arteries. Thin section electron microscopy revealed that endothelial cells of the neoformed vessels were plump, presented large nuclei, and showed numerous pinocytotic vesicles that were also observed in subendothelial pericytes. The alveoli of the bleomycin-treated rats were heterogeneous in size and shape in contrast with the homogeneity of alveoli of control animals. The alveolar capillaries of fibrotic lungs appeared to occupy a larger volume of the alveolar wall than alveolar capillaries of control rats. Our findings indicate that lung fibrosis encompasses marked changes of the vascular system, namely, the neoformation of vessels and the rearrangement of alveolar capillaries. These structural changes suggest that fibrotic transformation of the lung is associated with the local generation of angiogenic stimuli.

Animals↗
PubMed2005

Changes in the distribution and fine structure of the intralobular blood vessels of the submandibular gland in the postnatally developing mouse.

Previous studies have shown that the blood vessels supplying the endocrine organs and the mucosa of the intestinal canals change in terms of not only their distribution but also their structure with the development and growth of each organ. We examined changes in the distribution and structure of intralobular blood vessels, including capillaries, throughout the postnatal development of the submandibular gland, an exocrine organ. The mouse submandibular gland from days 0 (birth) to 49 was investigated chronologically and ultrastructurally. The capillaries changed from continuous to fenestrated on day 10, coincident with an increase in the number of acini to more than the number of terminal tubules. The number of sections of intralobular blood vessels per unit area gradually decreased with increasing acinar size and was lowest on day 21 when pups were weaned; the same number was maintained from then on. In contrast with the reduction in the number of intralobular blood vessels, the number of capillary pores appeared to increase gradually. Acinar size increased further till day 28. Capillary pore number also increased further, till day 35, apparently in relation to the increasing acinar size. These findings suggest that the changes in distribution and structure of the intralobular blood vessels in the submandibular gland of the postnatally developing mouse are closely related to the development of the parenchymal cells in preparation for weaning and sexual maturity.

Animals↗
PubMed1988

Blood flow in diabetics with foot lesions due to 'small vessel disease'.

Blood flow was measured in the feet and toes of 23 diabetics, 7 controls and 6 non-diabetic neuropathic controls, using venous occlusion plethysmography. All of the diabetics showed a characteristic flow abnormality with mild hyperperfusion of the foot at rest but impaired peak flow following arterial occlusion. When the diabetics were subdivided into those with 'small vessel disease', those with neuropathic ulceration and those with neuropathy but no ulceration, the groups had remarkably comparable blood flows, except that peak great toe blood flow was rather lower in small vessel disease. In small vessel disease, the combination of high resting blood flow and elevated foot venous oxygen saturation suggests that the hyperperfusion is due to arteriovenous shunting. It seems likely that the toe lesions ascribed to small vessel disease were in fact manifestations of severe diabetic neuropathy. The term small vessel disease should be avoided in the context of diabetic foot lesions.

Adult↗
PubMed1992

Measurements of central blood vessels in infants and children: normal values.

In order to provide physicians interpreting vascular radiographic studies with normal data regarding central blood vessel size in children and to facilitate the design and adaptation of intravascular devices for pediatric use, we measured lengths and diameters of central blood vessels in 141 radiographic studies in 136 children. The diameters of the following vessels were determined: right and left internal jugular veins and common carotid arteries; the inferior vena cava and the descending thoracic aorta; right and left iliac veins; and right and left femoral veins and arteries. In addition, the lengths of the inferior vena cava and the descending aorta were also determined. Blood vessel dimensions were highly correlated with age, height, weight, and body surface area. The linear regression equations for each measured dimension against age, weight, height, and surface area are provided, along with a table of predicted vessel size as a function of age.

Adolescent↗
PubMed2004

Novel growth stent for the permanent treatment of vessel stenosis in growing children: an experimental study.

Stent implantation in stenotic vessels of infants and small children is problematic because there is no ideal stent model that is small enough to be easily introduced into the infant femoral vein or artery and, at the same time, large enough to be dilated during growth to adult vessel diameters. To overcome this problem, we designed a new stent, the growth stent. This growth stent is a balloon-expandable metal stent. Two longitudinal halves are connected with bioabsorbable sutures so that a circular stent is created. It was postulated that after absorption of the sutures the stent would not impede growth. Twenty of these stents were implanted in the aorta, pulmonary arteries, and inferior vena cava of piglets (average weight 6.9 kg). After 18 weeks (14-23 weeks) and a mean weight gain of 59 kg, none of the stented vessels showed any significant stenosis or pressure gradient, documented by angiography and catheter pullback. During fluoroscopy, the two halves of the stent were clearly separated in all animals. The growth stent has the potential to be nonrestrictive during vessel growth, and thus is a promising new device for the permanent treatment of stenotic vessels in infancy and childhood.

Aging↗
PubMed2007

Concurrent implantation of sirolimus- and paclitaxel-eluting stents in the same vessel.

OBJECTIVE: To assess the safety and efficacy of concurrent implantation of sirolimus-eluting (SES) and paclitaxel-eluting (PES) stents in the same coronary artery. BACKGROUND: When it is impossible to deliver multiple drug eluting stents (DES) of the same type, the operator must opt to implant a different DES or a bare metal stent. There are currently no published data evaluating this approach. METHODS: We identified all cases in which one or more SES and PES were implanted in either the same lesion or adjacent segments of the same vessel during a single procedure between March 2003 and March 2005. Endpoints analyzed were; in-hospital major adverse cardiac events (MACE), and follow-up MACE (including stent thrombosis). RESULTS: We identified 44 patients with 89 lesions. This was a complex cohort of patients with a median of 3.5 stents implanted, 3 lesions and 2 vessels treated and a median stent length implanted of 80.5 mm, while 83% of the lesions were type B2/C. Eight patients had peri-procedural myocardial infarction. During follow-up; 1 cardiac death occurred, no patients had a myocardial infarct or stent thrombosis, 11 underwent target lesion and vessel revascularization (25%) and 13 had a major adverse cardiac event (29.5%). CONCLUSIONS: In this cohort of patients, the concurrent use of SES and PES in the same vessel was associated with outcomes in keeping with the complexity of disease treated. Our data show that it is not unreasonable to implant different DES in the same vessel, although we would not advocate this as routine practice.

Aged↗
PubMed1998

Changes in lymph vessels and portal veins in the portal tract of patients with idiopathic portal hypertension: a morphometric study.

Little is known about the effects of the pathological process associated with idiopathic portal hypertension (IPH) on hepatic lymph vessels or lymph flow. We used morphometric analysis to examine IPH-associated changes in lymph vessels and branches of the portal vein, with use of immunohistochemical staining for alpha smooth muscle actin. We also quantitated these changes using an image analysis system. The study was conducted with use of liver wedge biopsy material from 10 patients with advanced IPH and 10 control samples from patients with gastric carcinoma without liver disease. The number of lymph vessels, identified by a lack of smooth muscle layer in the wall, and the ratio of the total area of these vessels to that of the portal tract were higher in IPH samples than in the control samples, but the ratio of the area of a single lymph vessel to that of the portal tract in IPH samples was not different from control samples. The number of portal vein branches, characterized by hypertrophy of the smooth muscle layer in IPH samples was not different from control samples. The ratio of the total area of these branches to that of the portal tract, and the ratio of a single portal vein branch to that of the portal tract, were lower in IPH samples than in the control samples. Our results suggest that these morphometric changes in IPH may be associated with a reduction in portal blood flow and increased lymph flow, and that the latter may in turn reduce the high portal vein pressure in idiopathic portal hypertension.

Adult↗
PubMed2002

Melphalan availability in hypoxia-inducible factor-1alpha+/+ and factor-1alpha-/- tumors is independent of tumor vessel density and correlates with melphalan erythrocyte transport.

Many tumors are impervious to anticancer agents. Resistance due to lack of cytotoxic penetration into the tumor is often overlooked but can play a significant role in undermining therapy. Insufficient and irregular vascularization of tumors is a possible barrier to drug delivery, but there are others, e.g., impaired vessel permeability and poor interstitial transport. We evaluated the importance of tumor vessel density in the availability of melphalan to tumors. A nude mouse tumor model with different vascularization due to a single-gene deletion of hypoxia-inducible factor 1alpha (HIF-1alpha(+/+) and HIF-1alpha(-/-) embryonic stem cell-derived tumors) was used. The availability of melphalan to HIF-1alpha(+/+) (n = 20) and HIF-1alpha(-/-) (n = 23) tumors was not significantly different (p = 0.12). Furthermore, in the various subgroup analyses accentuating the difference in vessel density, no significant correlation between vessel density and melphalan availability was found. In the second part of the study, melphalan, was demonstrated to be transported in blood in mice with a distribution of 24% in erythrocytes vs. 76% in plasma. A strong correlation (r = 0.93, p < 0.000001) between melphalan concentrations in plasma and erythrocytes was found, indicating an equilibrium between these 2 compartments. Plasma and erythrocyte concentrations of melphalan are correlated with the tumor availability of melphalan (r = 0.66 and 0.64, respectively, both p < 0.001). These data suggest that tumor vessel density is not an important predictor of the tumor availability of small cytotoxic drugs such as melphalan and indicate the importance of erythrocytes in the transport of melphalan.

Animals↗
PubMed2003

Altered tumor vessel maturation and proliferation in placenta growth factor-producing tumors: potential relationship to post-therapy tumor angiogenesis and recurrence.

Cells in human tumor xenografts express similar levels of angiogenic growth factors before treatment. After radioimmunotherapy (RAIT) surviving tumor cells upregulate angiogenic growth factors, including placenta growth factor (PlGF), in a tumor-specific pattern. To determine the role of post-treatment PlGF expression on blood vessel recovery, tumor xenografts were assayed for post-RAIT vessel density (CD34+), proliferation (PCNA+) and maturity (SMA+ pericytes/mural cells). To further analyze the role of PlGF in blood vessel formation, PlGF-containing Matrigel implants were also assessed in a similar manner. The xenografts producing post-treatment PlGF increased CD34+ microvessel density 2- to 4-fold over untreated controls (p < 0.05) within 3 weeks of RAIT treatment. The proportion of mature microvessels (SMA+) decreased. Pericyte coverage and density of microvessels remained stable in the tumor that expressed neither PlGF nor VEGF after treatment. Hemoglobin content of PlGF-containing Matrigel implants was 5.7-fold that of anti-PlGF/anti-VEGF treated controls (Day 6, p < 0.03). The vessel density in PlGF-implants averaged 36.8 +/- 10.6/mm compared to 4.9 +/- 6.5/mm(2) in controls (p < 0.001). Vessels of PlGF-implants were lined by vWF+ cells, which were mostly flt-1+. These findings point to a role for PlGF in rapid restoration of tumor blood supply after treatment and thus, to enhanced likelihood of tumor regrowth. Likewise, the cells of primary human tumors that upregulate PlGF after treatment may be more likely to survive and form recurring tumors. Prevention of this angiogenic response to treatment may require administration of anti-angiogenic therapy during, rather than after, treatment.

Angiogenesis Inducing Agents↗
PubMed1992

Mechanical properties of fibrin adhesives for blood vessel anastomosis.

Various methods have been used for anastomosing, or attaching, two ends of a severed blood vessel together. The most common method, suturing, is tedious, can be time-consuming, and requires special training in microvascular surgery. Other methods, such as mechanical devices and lasers, have some problems as well. The use of fibrin adhesives for blood vessel anastomosis might eliminate some of the current problems by allowing a quicker, simpler, and more reliable method of attachment. Although mechanical studies have been conducted to determine fibrin glue properties in shear, tensile, and burst tests; most of these studies have used skin or intestinal tissue. Therefore, to evaluate the feasibility of using fibrin glue as an adhesive for blood vessel anastomosis, the mechanical properties of blood vessels joined with fibrin glue were examined using tensile and burst tests. High and low fibrinogen concentrations were tested after 5- or 45-min time periods. In addition, three clinical methods of attachment were compared: end-to-end anastomosis, vessel overlapping, and suturing. In this study, because the adhesive strength was not found to increase significantly after 5 min, setting times for fibrin glue may be short enough to make it a clinical option when compared to suturing. In addition, the higher fibrinogen concentration did not result in a significantly higher adhesive strength, indicating that the lower concentration fibrin adhesives may be of comparable strength to the higher concentrations for clinical applications.

Anastomosis, Surgical↗
PubMedDate not supplied

Gadolinium-enhanced high-resolution MR angiography with adaptive vessel tracking: preliminary results in the intracranial circulation.

To overcome problems associated with poor contrast between vessels and background tissue in time-of-flight magnetic resonance angiography, the role of intravenous gadopentetate dimeglumine in conjunction with a postprocessing adaptive vessel tracking scheme was studied. Vessel tracking makes it possible to discriminate arteries from veins, to prevent problems associated with other bright tissues on maximum-intensity projections, and to increase the signal-to-noise ratio. Short, asymmetric, velocity-compensated field echoes were used in conjunction with high-resolution imaging techniques to spatially discriminate between adjacent vessels and stationary background tissue. Gadopentetate dimeglumine was shown to be useful for visualization of small vessels, aneurysms, and regions of slow flow, when used with this post-processing scheme.

Adolescent↗
PubMedDate not supplied

Automated local maximum-intensity projection with three-dimensional vessel tracking.

Despite the simplicity and widespread acceptance of the maximum-intensity-projection (MIP) technique for displaying three-dimensional (3D) magnetic resonance angiographic data, several disadvantages are associated with MIP as it is applied to all of the 3D data. These include elevated noise level, reduced contrast between small vessels and background tissue, and the inability to distinguish arteries from veins. The authors have developed a 3D vessel tracking method combined with a local MIP around a given vessel to complement conventional MIP and alleviate these problems. The method is referred to as a traveling MIP (TMIP). TMIP was evaluated in both patients and healthy volunteers. The results indicate that TMIP provides better contrast between vessels and background tissue, better lumen definition, and better vascular visualization than either MIP or vessel tracking alone.

Algorithms↗
PubMedDate not supplied

Experimental and theoretical studies of vessel contrast-to-noise ratio in intracranial time-of-flight MR angiography.

CNR studies were performed for human intracranial vessels in 3D MRA data sets. The CNR dependency of different imaging parameters, such as flip angle, field of view, echo time, repetition time, and echo readout symmetry, was studied for vessels in the region of the circle of Willis. A theoretical model was developed for MR vascular imaging based on the Bloch equations and Fourier imaging theory. This model predicts the MR image intensity of vessels from basic subject parameters, such as the relaxation times of blood and stationary tissue, vessel dimension, and flow velocity, and the parameters of the imaging technique, such as flip angle, voxel volume, repetition time, and echo time. For most experiments, the model was found to fit the experimental results well. The validity of this model allows the optimization of imaging parameters to maximize vessel CNR in MR angiography.

Adult↗
PubMed2003

Enhanced tissue plasminogen activator synthesis by the sympathetic neurons that innervate aging vessels.

We investigated the source of the increased release of tissue plasminogen activator (t-PA) into the circulation that occurs during natural aging. Both the basal release and the acute stress-associated release induced by sympathetic stimulations are greater in older subjects. It is widely assumed that the source of these increases is vascular endothelium. However, the sympathetic neurons that densely innervate resistance vessel walls were recently shown to synthesize and transport active t-PA to axon terminals in vascular smooth muscle, suggesting an alternative source. These fine t-PA-bearing axons lie in the seldom-studied deep adventitia of vessel walls, where they are less visible than endothelium in tissue sections. Using Northern blot analysis, we observed that t-PAmRNA synthesis is increased 54% in the ganglion parent neuron cell bodies that innervate aged vessels. The t-PA release from isolated, aged ganglia in cultures was twofold greater than that from younger controls. In addition, aged whole-artery explants showed a 20% greater basal and a 50% greater acute release of stored t-PA in vitro. In vivo levels of active t-PA were 33% greater in the blood and 40% greater in the aqueous humor. These results are consistent with an increased infusion of the active t-PA protease from sympathetic axon terminals into the vessel wall extracellular matrix and the blood during natural aging, in addition to the basal endothelial release. We suggest that the cumulative impact of an accelerated plasmin production and matrix degradation within vessel walls, especially during repetitive stress, may play an unrecognized role in the pathogenesis of vascular aging. The possibility that increased sympathetic nervous system plasminogenesis influences the aging process in nonvascular tissues also deserves further investigation.

Adrenergic Fibers↗
PubMed1977

Prognostic significance of blood vessel invasion in carcinoma of the breast in women.

Prognostic significance of blood vessel invasion in carcinoma of the female breast has been evaluated by study of 242 cases of radical mastectomy done at the Tata Memorial Hospital. The significance of axillary node involvement with the disease has been simultaneously evaluated. In the absence of blood vessel invasion and lymph node metastasis the 5 year survival rate was 98%. Compared with this, 5 year survival rate was reduced to 59% when the blood vessel invasion was present but no lymph node metastasis. Only 12% survived for 5 years when both blood vessels and lymph nodes were involved with the disease. The study indicated that blood vessel invasion in the primary breast carcinoma is more significant than lymph node metastasis.

Adult↗
PubMed1982

Heat-induced contraction of blood vessels.

Heat-induced spontaneous contraction of blood vessels as observed during the application of surgical lasers was investigated experimentally. By means of extravascular irrigation of veins and arteries from the rabbit mesentery in vivo with saline that had been preheated to varying temperatures in the range of 45-90 degrees C, the temperature dependence on contraction with evaluated. It was demonstrated that lower temperature thresholds of approximately 70 degrees C and 75 degrees C exist for the shrinkage of veins and arteries, respectively. Ultrastructural investigation of the walls of contracted and of noncontracted vessels indicates that vessel contraction correlates with the denaturation of collagen fibrils. It was therefore concluded that the well-known heat shrinkage effect of denatured collagen accounts for the heat-induced vessel constriction. It is shown that on heat-induced permanent occlusion, vessels of the type that were examined cannot be achieved reliably at temperatures of up to 90 degrees C for 16 sec; in most cases relaxation takes place.

Animals↗
PubMed2004

Imaging of small vessels using photoacoustics: an in vivo study.

BACKGROUND AND OBJECTIVES: The ability to correctly visualize the architectural arrangement of microvasculature is valuable to many diverse fields in medicine. In this study, we applied photoacoustics (PA) to obtain high-resolution images of submillimeter blood vessels. STUDY DESIGN/MATERIALS AND METHODS: Short laser pulses are used to generate ultrasound from superficial blood vessels in several animal models. From these ultrasound waves the interior of blood vessels can be reconstructed. RESULTS: We present results from a novel approach based on the PA principle that allows specific in vivo visualization of dermal blood vessels without the use of contrast agents or ionizing radiation. CONCLUSIONS: We show PA images of externalized blood vessels and demonstrate in vivo PA imaging of vasculature through layers of skin varying in thickness.

Acoustics↗

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