Search results for "blood vessel"
showing 10 items of 323 documents
The effects of linearly increasing flip angles on 3D inflow MR angiography
1994
As recently demonstrated, spin saturation effects in 3D time-of-flight (TOF) MR angiography (MRA) can be reduced by using RF pulses with linearly increasing flip angles (ramp pulses) in the main direction of flow. We developed a model for calculating the signal distribution of proton flow within the excitation volume (slab) for different ramp slopes and compared the results with the measured distribution for the lower-leg arteries. The ramp pulses were generated using the Fourier transformation of the desired excitation profiles. With a bandwidth of 6 kHz and a pulse length of 2.56 ms satisfactory ramps with variable slopes were generated and applied in a standard flow-compensated 3D FISP s…
Micrometer-resolution reconstruction and analysis of whole mouse brain vasculature by synchrotron-based phase-contrast tomographic microscopy
2021
AbstractNervous tissue metabolism is mainly supported by the dense thread of blood vessels which mainly provides fast supplies of oxygen and glucose. Recently, the supplying role of the brain vascular system has been examined in major neurological conditions such as the Alzheimer’s and Parkinson’s diseases. However, to date, fast and reliable methods for the fine level microstructural extraction of whole brain vascular systems are still unavailable. We present a methodological framework suitable for reconstruction of the whole mouse brain cerebral microvasculature by X-ray tomography with the unprecedented pixel size of 0.65 μm. Our measurements suggest that the resolving power of the techn…
Assessment of conduit artery vasomotion using photoplethysmography
2013
Vasomotion is a spontaneous oscillation of vascular tone. The phenomenon has been observed in small arterioles and capillaries as well as in the large conduit arteries. The layer of smooth muscle cells that surrounds a blood vessel can spontaneously and periodically change its tension and thereby the arterial wall stiffness also changes. As the understanding of the phenomenon is still rather obscure, researchers would benefit from a low-cost and reliable investigation technique such as photoplethysmography (PPG). PPG is an optical blood pulsation measurement technique that can offer substantial information about the arterial stiffness. The aims of this pilot study were to evaluate the usefu…
Structure and closure mechanism of the human umbilical artery
1978
The structure of the fully-patent umbilical artery and rearrangement of its structural elements with postnatal closure were examined in 10 centimeter long umbilical cord segments which were double-clamped at different time intervals after delivery. The fully-patent umbilical artery consists of two main layers: an outer layer of circularly arranged smooth muscle cells and an inner layer which shows rather irregularly and loosely arranged cells embedded in abundant metachromatic ground substance. No predominantly longitudinal arrangements of cells and fibers reported by earlier investigators could be identified in the inner layer. Closure of the umbilical arteries is initiated by numerous loc…
AdVEGF165gene transfer increases survival in overdimensioned skin flaps
2004
Background Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. VEGF A also plays an important role in wound healing of the skin by promoting angiogenesis and by stimulating blood vessel growth. Therefore we tested the hypothesis that flap survival could be increased by the preoperative injection of AdVEGF165. Methods We studied the effect of AdVEGF165 in an overdimensioned ischemic random-pattern-flap model in the rat (n = 50) with a length-to-width ratio of 4 : 1. VEGF cDNA was administered in two concentrations of 5 × 108 plaque-forming units (pfU) and 1 × 109 pfU using a recombinant adenoviral vector. Recombinant virus was injected subdermally 7, 3 or 0 days pri…
Expression of the proto-oncogene c-myc in human stenotic aortocoronary bypass grafts.
2002
Summary Proliferation and differentiation of vascular smooth muscle cells (VSMC) are central events in vascular pathobiology and play a major role in the development of stenotic and restenotic lesions [ 15, 27 ] . The proto-oncogene c-myc and other early cell cycle-regulating genes have been implicated in the induction of cell proliferation and differentiation under diverse pathophysiological conditions [ 11, 13 ] . In the present study we analyzed c-myc mRNAexpression by indirect nonradioactive in situ hybridization technique (NISH) in human stenotic venous bypass grafts (n = 32) retrieved during re-do operations of coronary artery disease and compared the results with 28 native veins (ven…
Evaluation of the healing of precoated vascular dacron prostheses.
1991
Knitted and woven Dacron grafts commercially coated with bovine collagen, gelatin and human albumin were implanted end-to-side between the infrarenal aorta and the bifurcation in 35 growing pigs. Grafts were explanted after 4, 8 and 12 weeks and compared to 6 uncoated knitted prostheses preclotted with blood that served as a control. Uncoated grafts rapidly developed a firmly attached neointima lined with endothelium. Compared with coated grafts the thrombus-free area of uncoated grafts was significantly larger (P less than 0.05). The slow resorption of albumin resulted in a delayed and incomplete neointimal healing and failing graft incorporation. Although the bovine collagen was only mini…
Neuropathological Alterations after Smoke Inhalation Injury, with and without Skin Burn
2020
More than 23,000 smoke inhalation injuries are reported in the United States each year. While the pathophysiology of smoke inhalation-induced lung injury is well studied, little is known about the acute effects of smoke inhalation on the central nervous system (CNS). Tragic events, such as those of the nightclub fire in Brazil in 2013, suggest that neurological complications occur following smoke inhalation injury, with the most commonly reported symptoms being a persistent headache, memory loss, and paresthesia. Additionally, one case report described that smoke inhalation alone was associated with progressive cognitive and psychiatric impairments, lasting for years after the initial injur…
Comparative Antiproliferative and Antiangiogenic Activity of Cacao Preparations (P06-048-19)
2019
OBJECTIVES: Multiple lines of evidence show the benefits of cacao on inflammation and cardiovascular disease. The relationship between cacao and cancer is less well defined. Cacao contains bioactive compounds with antiangiogenic properties, such as procyanidins and catechins. Angiogenesis, blood vessel formation, is critical for tumor growth and validated target in cancer therapy. We studied the antiangiogenic and anti-tumorigenic potential of two commercially available 100% cacaos (Valrhona and De Zaan). METHODS: L5178y mouse lymphoma cells were incubated with different concentrations of cacao (0, 0.1, 0.3, 1, 3, and 10 µl/ml). The calorimetric methylthiazolyldiphenyl-tetrazolium bromide (…
Editor's Choice – European Society for Vascular Surgery (ESVS) 2021 Clinical Practice Guidelines on the Management of Venous Thrombosis
2021
European Society for Vascular Surgery (ESVS) 2021 Clinical Practice Guidelines on the Management of Venous Thrombosis