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1

Branching Blood Vessels  

NSDL National Science Digital Library

This activity explores some of the factors that affect blood flow in branching vessels and is designed for AP Biology, Anatomy & Physiology, and Physics. You may want to do this as activity as a series of labs or you can assign the problems to different groups. After conducting this lab myself, I suggest that you practice it yourself before doing it in class. Be sure that your tubing and funnel fit snugly. Also, make sure that your clamps and Y-connectors fit snugly with the tubing as well.

Mr. Jonathan Borne (Union Springs Academy)

2000-08-01

2

Blood Vessels  

NSDL National Science Digital Library

Part of the circulatory system is composed of a series of tubes carries the vital elements and the wastes that keep us strong and healthy. Take a look at these amazing vessels and how they work together. Ever cut yourself on the toe? How about the finger? The ear? Ever get a bloody nose? How about a scrape on the knee? If these things have ever happened to you then you already know that blood vessels carry blood to EVERY part of the body. They start out ...

Mrs. Hirschi

2007-11-20

3

Blood Vessel Tension Tester  

NASA Technical Reports Server (NTRS)

In the photo, a medical researcher is using a specially designed laboratory apparatus for measuring blood vessel tension. It was designed by Langley Research Center as a service to researchers of Norfolk General Hospital and Eastern Virginia Medical School, Norfolk, Virginia. The investigators are studying how vascular smooth muscle-muscle in the walls of blood vessels-reacts to various stimulants, such as coffee, tea, alcohol or drugs. They sought help from Langley Research Center in devising a method of measuring the tension in blood vessel segments subjected to various stimuli. The task was complicated by the extremely small size of the specimens to be tested, blood vessel "loops" resembling small rubber bands, some only half a millimeter in diameter. Langley's Instrumentation Development Section responded with a miniaturized system whose key components are a "micropositioner" for stretching a length of blood vessel and a strain gage for measuring the smooth muscle tension developed. The micropositioner is a two-pronged holder. The loop of Mood vessel is hooked over the prongs and it is stretched by increasing the distance between the prongs in minute increments, fractions of a millimeter. At each increase, the tension developed is carefully measured. In some experiments, the holder and specimen are lowered into the test tubes shown, which contain a saline solution simulating body fluid; the effect of the compound on developed tension is then measured. The device has functioned well and the investigators say it has saved several months research time.

1978-01-01

4

Blood Vessels of the Fetal Pig Dissection Posterior Vessels Protocol  

E-print Network

Blood Vessels of the Fetal Pig Dissection Posterior Vessels Protocol: 1. The blood vessels membrane is the peritoneum, the blood vessels are said to be retroperitoneal). In order to see the blood that supplies the stomach, liver and spleen with blood. This is the celiac artery. c. Just below where

Loughry, Jim

5

HEART AND BLOOD VESSELS CARDIOVASCULARCARDIOVASCULAR  

E-print Network

· Lymphatic system collects excess tissue fluid and returns it to the cardiovascular system. TYPES OF BLOODHEART AND BLOOD VESSELS CARDIOVASCULARCARDIOVASCULAR SYSTEMSYSTEM SYSTEM COMPONENTS & FUNCTIONSSYSTEM COMPONENTS & FUNCTIONS SYSTEM COMPONENTS & FUNCTIONSSYSTEM COMPONENTS & FUNCTIONS · Functions

Cochran-Stafira, D. Liane

6

Blood Vessels Help Tumors Grow  

NSDL National Science Digital Library

In this video segment, adapted from NOVA, Dr. Judah Folkman uses the scientific method to discover how cancer cells induce the formation of new blood vessels, which in turn nourish those cancer cells.

2007-04-19

7

Regenerating Blood Vessels  

Microsoft Academic Search

\\u000a Maintaining coronary artery blood flow and myocardial perfusion is critically important for the survival and function of cardiac\\u000a muscle. Stem cells can contribute to the generation and maintenance of vascular networks that support the myocardium either\\u000a directly, as a source of new vascular cells, or indirectly, by secreting soluble factors to promote angiogenesis. In addition\\u000a to generating microvascular networks, stem

Tracy A. Gwyther; Marsha W. Rolle

8

Exploring the Elasticity of Blood Vessels  

NSDL National Science Digital Library

The two main blood vessels of the body are arteries and veins. The heart pumps blood out to the body by way of arteries with veins carrying the blood back to the heart. Blood within these vessels is under pressure. Students will explore the differences in elasticity and whether this in turn affects the pressure within these vessels. As an optional extension to this activity students will explore the effects of arteriosclerosis and blood clots on blood flow.

2000-07-01

9

Blood Vessels of the Future  

NSDL National Science Digital Library

Forty-ninth monthly installment of our "What A Year!" website project, introducing life science breakthroughs to middle and high school students and their teachers. The use of bioengineered blood vessels in place of grafts could reduce the number of surgeries needed by dialysis patients and increase the effectiveness of each treatment. It could also simplify coronary artery bypass graft surgery by eliminating the need to find a usable artery somewhere else in the patient.

2011-06-03

10

THE FAKS ABOUT BLOOD VESSEL ASSEMBLY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Potential role of FAK in blood vessel assembly. The process of vessel assembly can be dissected into discernible steps (A), and there is evidence to suggest that FAK is involved throughout. In FAK-/- mutants (B), blood vessel assembly is arrested during tubulogenesis, suggesting that the primary rol...

11

Unsteady Flow in Stenotic Blood Vessels  

NASA Astrophysics Data System (ADS)

Recent studies show that many heart attacks and strokes occur from sudden rupture of partially occluding atherosclerotic plaque rather than total vessel occlusion. Our goal is to understand how the mechanical forces induced by blood flow on specific plaque deposits makes them vulnerable to rupture. Models of severely stenotic carotid bifurcations are created from MR images and grids generated for the flow domains. The three-dimensional, unsteady, incompressible Navier-Stokes equations in finite-volume form are solved numerically using physiological boundary conditions. During systole a high velocity jet forms at the stenotic throat in one of the branches, and a long recirculation zone is observed downstream of the plaque. During diastole the flow is more stagnant. The flow is highly three-dimensional and unsteady with chaotic streamlines. Whereas flow in healthy arteries is laminar, irregular geometries and sharp changes in vessel diameter of a severely stenotic artery significantly disrupt the flow, with consequences for shear and normal wall stresses at the wall, and important implications for plaque stability. Supported by NIH Grant HL61823

Rayz, Vitaliy L.; Devi Williamson, Shobha; Berger, Stanley A.; Saloner, David

2003-11-01

12

Automated computational framework of blood vessel quantification in chick chorioallantoic membrane angiogenesis  

NASA Astrophysics Data System (ADS)

Chick chorioallantoic membrane (CAM) angiogenesis assay has been widely used for finding drugs targeting new blood vessel development in cancer research. In addition to the setup materials and protocols, laboratory findings depend on the quantification and analysis of microscopic blood vessel images. However, it is still a challenging problem because of the high complexity of blood vessel branching structures. We applied preprocessing on CAM microscopic images by keeping the integrity of minor branches in the vessel structure. We then proposed an efficient way to automatically extract blood vessel centerlines based on vector tracing starting from detected seed points. Finally, all branches were coded to construct an abstract model of the branching structure, which enabled more accurate modeling for in-depth analysis. The framework was applied in quantifying Icaritin (ICT) inhibition effects on angiogenesis in a CAM model. Experimental results showed the high accuracy in blood vessel quantification and modeling compared with semimanual measurements. Meanwhile, a set of blood vessel growth indicators were extracted to provide fully automated analysis for angiogenesis assays. Further analysis proved that ICT took effect in a dose-dependent manner which could be applied in suppressing tumor blood vessel growth.

Shi, Peng; Hong, Jinsheng; Huang, Yue; Zhang, Zhenhuan; Zhang, Mei; Zhang, Lurong

2014-10-01

13

Accurate segmentation of blood vessels from 3D medical images  

Microsoft Academic Search

The authors' work contributes to the accurate segmentation of blood vessels from 3D medical images. The blood vessel axis and surface are optimized in an alternating way. Starting from an initial blood vessel axis estimate, slices are resampled in the 3D data volume perpendicular to this axis. In these slices, blood vessel contour candidate points are extracted at maximum gradient

B. Verdonck; L. Bloch; H. Maitre; D. Vandermeulen; P. Suetens; G. Marchal

1996-01-01

14

Trends in Tissue Engineering for Blood Vessels  

PubMed Central

Over the years, cardiovascular diseases continue to increase and affect not only human health but also the economic stability worldwide. The advancement in tissue engineering is contributing a lot in dealing with this immediate need of alleviating human health. Blood vessel diseases are considered as major cardiovascular health problems. Although blood vessel transplantation is the most convenient treatment, it has been delimited due to scarcity of donors and the patient's conditions. However, tissue-engineered blood vessels are promising alternatives as mode of treatment for blood vessel defects. The purpose of this paper is to show the importance of the advancement on biofabrication technology for treatment of soft tissue defects particularly for vascular tissues. This will also provide an overview and update on the current status of tissue reconstruction especially from autologous stem cells, scaffolds, and scaffold-free cellular transplantable constructs. The discussion of this paper will be focused on the historical view of cardiovascular tissue engineering and stem cell biology. The representative studies featured in this paper are limited within the last decade in order to trace the trend and evolution of techniques for blood vessel tissue engineering. PMID:23251085

Nemeno-Guanzon, Judee Grace; Lee, Soojung; Berg, Johan Robert; Jo, Yong Hwa; Yeo, Jee Eun; Nam, Bo Mi; Koh, Yong-Gon; Lee, Jeong Ik

2012-01-01

15

Blood vessels as targets in tumor therapy  

PubMed Central

The landmark papers published by Judah Folkman in the early 1970s on tumor angiogenesis and therapeutic implications promoted the rapid development of a very dynamic field where basic scientists, oncologists, and pharmaceutical industry joined forces to determine the molecular mechanisms in blood vessel formation and find means to exploit this knowledge in suppressing tumor vascularization and growth. A wealth of information has been collected on angiogenic growth factors, and in 2004 the first specific blood vessel-targeted cancer therapy was introduced: a neutralizing antibody against vascular endothelial growth factor (VEGF). Now (2011) we know that suppression of tumor angiogenesis may be a double-edged sword and that the therapy needs to be further refined and individualized. This review describes the hallmarks of tumor vessels, how different angiogenic growth factors exert their function, and the perspectives for future development of anti-angiogenic therapy. PMID:22348394

2012-01-01

16

Blackworms, Blood Vessel Pulsations and Drug Effects.  

ERIC Educational Resources Information Center

Introduces the freshwater oligochaete worm, lumbriculus variegatus (common name: blackworms), an organism that is well suited for classroom study because of its closed circulatory system. Describes a set of simple, fast, noninvasive, and inexpensive methods for observing pulsations of the worm's dorsal blood vessels under baseline conditions, and

Lesiuk, Nalena M.; Drewes, Charles D.

1999-01-01

17

Lattice Boltzmann simulation of blood flow in digitized vessel networks  

PubMed Central

Efficient flow of red blood cells (RBCs) and white blood cells (WBCs) through the microcirculation is necessary for oxygen and nutrient delivery as well as immune cell function. Because blood is a dense particulate suspension, consisting of 40% RBCs by volume, it is difficult to analyze the physical mechanisms by which individual blood cells contribute to the bulk flow properties of blood. Both experimental and computational approaches are hindered by these non-Newtonian properties, and predicting macroscopic blood flow characteristics such as viscosity has historically been an empirical process. In order to examine the effect of the individual cells on macroscopic blood rheology, we developed a lattice Boltzmann model that considers the blood as a suspension of particles in plasma, accounting explicitly for cell-cell and cell-wall interactions. Previous studies have concluded that the abundance of leukocyte rolling in postcapillary venules is due to interactions between red blood cells and leukocytes as they enter postcapillary expansions. Similar fluid dynamics may be involved in the initiation of rolling at branch points, a phenomenon linked to atherosclerosis. The lattice Boltzmann approach is used to analyze the interactions of red and white blood cells as they flow through vascular networks digitized from normal and tumor tissue. A major advantage of the lattice-Boltzmann method is the ability to simulate particulate flow dynamically and in any geometry. Using this approach, we can accurately determine RBC-WBC forces, particle trajectories, the pressure changes in each segment that accompany cellular traffic in the network, and the forces felt by the vessel wall at any location. In this technique, intravital imaging using vascular contrast agents produces the network outline that is fed to the lattice-Boltzmann model. This powerful and flexible model can be used to predict blood flow properties in any vessel geometry and with any blood composition. PMID:19343080

Sun, Chenghai; Munn, Lance L.

2008-01-01

18

Automated measurement of retinal blood vessel tortuosity  

NASA Astrophysics Data System (ADS)

Abnormalities in the vascular pattern of the retina are associated with retinal diseases and are also risk factors for systemic diseases, especially cardiovascular diseases. The three-dimensional retinal vascular pattern is mostly formed congenitally, but is then modified over life, in response to aging, vessel wall dystrophies and long term changes in blood flow and pressure. A characteristic of the vascular pattern that is appreciated by clinicians is vascular tortuosity, i.e. how curved or kinked a blood vessel, either vein or artery, appears along its course. We developed a new quantitative metric for vascular tortuosity, based on the vessel's angle of curvature, length of the curved vessel over its chord length (arc to chord ratio), number of curvature sign changes, and combined these into a unidimensional metric, Tortuosity Index (TI). In comparison to other published methods this method can estimate appropriate TI for vessels with constant curvature sign and vessels with equal arc to chord ratios, as well. We applied this method to a dataset of 15 digital fundus images of 8 patients with Facioscapulohumeral muscular dystrophy (FSHD), and to the other publically available dataset of 60 fundus images of normal cases and patients with hypertensive retinopathy, of which the arterial and venous tortuosities have also been graded by masked experts (ophthalmologists). The method produced exactly the same rank-ordered list of vessel tortuosity (TI) values as obtained by averaging the tortuosity grading given by 3 ophthalmologists for FSHD dataset and a list of TI values with high ranking correlation with the ophthalmologist's grading for the other dataset. Our results show that TI has potential to detect and evaluate abnormal retinal vascular structure in early diagnosis and prognosis of retinopathies.

Joshi, Vinayak; Reinhardt, Joseph M.; Abramoff, Michael D.

2010-03-01

19

Microvascular Branching as a Determinant of Blood Flow by Intravital Particle Imaging Velocimetry  

NASA Technical Reports Server (NTRS)

The effects of microvascular branching on blood flow were investigated in vivo by microscopic particle imaging velocimetry (micro-PIV). We use micro-PIV to measure blood flow by tracking red blood cells (RBC) as the moving particles. Velocity flow fields, including flow pulsatility, were analyzed for the first four branching orders of capillaries, postcapillary venules and small veins of the microvascular network within the developing avian yolksac at embryonic day 5 (E5). Increasing volumetric flowrates were obtained from parabolic laminar flow profiles as a function of increasing vessel diameter and branching order. Maximum flow velocities increased approximately twenty-fold as the function of increasing vessel diameter and branching order compared to flow velocities of 100 - 150 micron/sec in the capillaries. Results from our study will be useful for the increased understanding of blood flow within anastomotic, heterogeneous microvascular networks.

Parsons-Wingerter, Patricia; McKay, Terri L.; Vickerman, Mary B.; Wernet, Mark P.; Myers, Jerry G.; Radhakrishnan, Krishnan

2007-01-01

20

Zinc oxide nanoflowers make new blood vessels  

NASA Astrophysics Data System (ADS)

It is well established that angiogenesis is the process of formation of new capillaries from pre-existing blood vessels. It is a complex process, involving both pro- and anti-angiogenic factors, and plays a significant role in physiological and pathophysiological processes such as embryonic development, atherosclerosis, post-ischemic vascularization of the myocardium, tumor growth and metastasis, rheumatoid arthritis etc. This is the first report of zinc oxide (ZnO) nanoflowers that show significant pro-angiogenic properties (formation of new capillaries from pre-existing blood vessels), observed by in vitro and in vivo angiogenesis assays. The egg yolk angiogenesis assay using ZnO nanoflowers indicates the presence of matured blood vessels formation. Additionally, it helps to promote endothelial cell (EA.hy926 cells) migration in wound healing assays. Formation of reactive oxygen species (ROS), especially hydrogen peroxide (H2O2)--a redox signaling molecule, might be the plausible mechanism for nanoflower-based angiogenesis. Angiogenesis by nanoflowers may provide the basis for the future development of new alternative therapeutic treatment strategies for cardiovascular and ischemic diseases, where angiogenesis plays a significant role.It is well established that angiogenesis is the process of formation of new capillaries from pre-existing blood vessels. It is a complex process, involving both pro- and anti-angiogenic factors, and plays a significant role in physiological and pathophysiological processes such as embryonic development, atherosclerosis, post-ischemic vascularization of the myocardium, tumor growth and metastasis, rheumatoid arthritis etc. This is the first report of zinc oxide (ZnO) nanoflowers that show significant pro-angiogenic properties (formation of new capillaries from pre-existing blood vessels), observed by in vitro and in vivo angiogenesis assays. The egg yolk angiogenesis assay using ZnO nanoflowers indicates the presence of matured blood vessels formation. Additionally, it helps to promote endothelial cell (EA.hy926 cells) migration in wound healing assays. Formation of reactive oxygen species (ROS), especially hydrogen peroxide (H2O2)--a redox signaling molecule, might be the plausible mechanism for nanoflower-based angiogenesis. Angiogenesis by nanoflowers may provide the basis for the future development of new alternative therapeutic treatment strategies for cardiovascular and ischemic diseases, where angiogenesis plays a significant role. Electronic supplementary information (ESI) available: See DOI: 10.1039/c2nr32369a

Barui, Ayan Kumar; Veeriah, Vimal; Mukherjee, Sudip; Manna, Joydeb; Patel, Ajay Kumar; Patra, Sujata; Pal, Krishnendu; Murali, Shruthi; Rana, Rohit K.; Chatterjee, Suvro; Patra, Chitta Ranjan

2012-11-01

21

RETINAL BLOOD VESSEL SEGMENTATION USING GEODESIC VOTING METHODS Youssef Rouchdy  

E-print Network

RETINAL BLOOD VESSEL SEGMENTATION USING GEODESIC VOTING METHODS Youssef Rouchdy and Laurent D to segment retinal blood vessels are presented. Many authors have used minimal cost paths, or similarly on the use of a set of such geodesic paths to extract retinal blood vessels, using minimal interaction

Cohen, Laurent

22

Hemoglobin ? in the blood vessel wall.  

PubMed

Hemoglobin has been studied and well characterized in red blood cells for over 100 years. However, new work has indicated that the hemoglobin ? subunit (Hb?) is also found within the blood vessel wall, where it appears to localize at the myoendothelial junction (MEJ) and plays a role in regulating nitric oxide (NO) signaling between endothelium and smooth muscle. This discovery has created a new paradigm for the control of endothelial nitric oxide synthase activity, nitric oxide diffusion, and, ultimately, vascular tone and blood pressure. This review discusses the current knowledge of hemoglobin?s properties as a gas exchange molecule in the bloodstream and extrapolates the properties of Hb? biology to the MEJ signaling domain. Specifically, we propose that Hb? is present at the MEJ to regulate NO release and diffusion in a restricted physical space, which would have powerful implications for the regulation of blood flow in peripheral resistance arteries. PMID:24832680

Butcher, Joshua T; Johnson, Tyler; Beers, Jody; Columbus, Linda; Isakson, Brant E

2014-08-01

23

Gene therapy method targets tumor blood vessels  

Cancer.gov

Working in mice, researchers at Washington University School of Medicine in St. Louis (home of the Alvin J. Siteman Cancer Center) report developing a gene delivery method long sought in the field of gene therapy: a deactivated virus carrying a gene of interest that can be injected into the bloodstream and make its way to the right cells. In this early proof-of-concept study, the scientists have shown that they can target tumor blood vessels in mice without affecting healthy tissues.

24

Perivascular cells in blood vessel regeneration  

PubMed Central

Vascular engineering seeks to design and construct functional blood vessels comprising endothelial cells and perivascular cells (PCs), with the ultimate goal of clinical translation. While endothelial behavior has been extensively investigated, PCs play an equally significant role in the development of novel regenerative strategies, providing functionality and stability to vessels. The two major classes of PCs are vascular smooth muscle cells (vSMCs) and pericytes; vSMCs can be further sub-classified as either contractile or synthetic. The inclusion of these cell types is crucial for successful regeneration of blood vessels. Furthermore, understanding distinctions between vSMCs and pericytes will enable improved therapeutics in a tissue-specific manner. Here we focus on the approaches and challenges facing the use of PCs in vascular regeneration, including their characteristics, stem cell sources, and interactions with endothelial cells. Finally, we discuss biochemical and microRNA (miR) regulators of PC behavior and engineering approaches that mimic various cues affecting PC function. PMID:23554249

Wanjare, Maureen; Kusuma, Sravanti; Gerecht, Sharon

2013-01-01

25

Method and device for supporting blood vessels during anastomosis  

DOEpatents

A device and method for preventing first and second severed blood vessels from collapsing during attachment to each other. The device comprises a dissolvable non-toxic stent that is sufficiently rigid to prevent the blood vessels from collapsing during anastomosis. The stent can be hollow or have passages to permit blood flow before it dissolves. A single stent can be inserted with an end in each of the two blood vessels or separate stents can be inserted into each blood vessel. The stent may include a therapeutically effective amount of a drug which is slowly released into the blood stream as the stent dissolves. 12 figs.

Doss, J.D.

1985-05-20

26

Photoacoustic removal of occlusions from blood vessels  

DOEpatents

Partial or total occlusions of fluid passages within the human body are removed by positioning an array of optical fibers in the passage and directing treatment radiation pulses along the fibers, one at a time, to generate a shock wave and hydrodynamics flows that strike and emulsify the occlusions. A preferred application is the removal of blood clots (thrombin and embolic) from small cerebral vessels to reverse the effects of an ischemic stroke. The operating parameters and techniques are chosen to minimize the amount of heating of the fragile cerebral vessel walls occurring during this photo acoustic treatment. One such technique is the optical monitoring of the existence of hydrodynamics flow generating vapor bubbles when they are expected to occur and stopping the heat generating pulses propagated along an optical fiber that is not generating such bubbles.

Visuri, Steven R. (Livermore, CA); Da Silva, Luiz B. (Danville, CA); Celliers, Peter M. (Berkeley, CA); London, Richard A. (Orinda, CA); Maitland, IV, Duncan J. (Lafayette, CA); Esch, Victor C. (San Francisco, CA)

2002-01-01

27

Quantitative assessment of angiogenesis, perfused blood vessels and endothelial tip cells in the postnatal mouse brain.  

PubMed

During development and in various diseases of the CNS, new blood vessel formation starts with endothelial tip cell selection and vascular sprout migration, followed by the establishment of functional, perfused blood vessels. Here we describe a method that allows the assessment of these distinct angiogenic steps together with antibody-based protein detection in the postnatal mouse brain. Intravascular and perivascular markers such as Evans blue (EB), isolectin B4 (IB4) or laminin (LN) are used alongside simultaneous immunofluorescence on the same sections. By using confocal laser-scanning microscopy and stereological methods for analysis, detailed quantification of the 3D postnatal brain vasculature for perfused and nonperfused vessels (e.g., vascular volume fraction, vessel length and number, number of branch points and perfusion status of the newly formed vessels) and characterization of sprouting activity (e.g., endothelial tip cell density, filopodia number) can be obtained. The entire protocol, from mouse perfusion to vessel analysis, takes ?10 d. PMID:25502884

Wlchli, Thomas; Mateos, Jos Mara; Weinman, Oliver; Babic, Daniela; Regli, Luca; Hoerstrup, Simon P; Gerhardt, Holger; Schwab, Martin E; Vogel, Johannes

2015-01-01

28

Quantitative analysis of blood vessel geometry  

NASA Astrophysics Data System (ADS)

Re-narrowing or restenosis of a human coronary artery occurs within six months in one third of balloon angioplasty procedures. Accurate and repeatable quantitative analysis of vessel shape is important to characterize the progression and type of restenosis, and to evaluate effects new therapies might have. A combination of complicated geometry and image variability, and the need for high resolution and large image size makes visual/manual analysis slow, difficult, and prone to error. The image processing and analysis described here was developed to automate feature extraction of the lumen, internal elastic lamina, neointima, external elastic lamina, and tunica adventitia and to enable an objective, quantitative definition of blood vessel geometry. The quantitative geometrical analysis enables the measurement of several features including perimeter, area, and other metrics of vessel damage. Automation of feature extraction creates a high throughput capability that enables analysis of serial sections for more accurate measurement of restenosis dimensions. Measurement results are input into a relational database where they can be statistically analyzed compared across studies. As part of the integrated process, results are also imprinted on the images themselves to facilitate auditing of the results. The analysis is fast, repeatable and accurate while allowing the pathologist to control the measurement process.

Fuhrman, Michael G.; Abdul-Karim, Othman; Shah, Sujal; Gilbert, Steven G.; Van Bibber, Richard

2001-07-01

29

The oral mucosal surface and blood vessels  

PubMed Central

Introduction Detailed information about the size of the oral mucosa is scarce in the literature, and those studies that do exist do not take into account the size of the tongue or the enlargement of the surface by the papillae. Because of the various functions of the oral mucosa in the maintenance of oral health, knowledge of its true size may provide a better understanding of the physiology of the oral cavity and some oral diseases and direct future therapeutic strategies. The aim of this study was to determine the total size of the oral mucosa. Methods Five human adult cadaver heads were cut in the median sagittal plane, and the total area of the oral surface was determined using silicon casts. The surface of the tongue was measured with quantitative profilometry. Photographs of oral blood vessels were taken in different areas of the oral mucosa of adult test subjects using intravital microscopy, and the pictures were compared with vessel casts of the oral mucosal capillaries of a maccaca fasciculrais monkey, which was studied using a scanning electron microscope. Results The results showed that the dorsal side of the tongue comprises a large proportion of the total oral mucosal surface. The surface area of the epithelium increases moving from anterior to posterior on the tongue, and the number of underlying blood vessels increases proportionally. Conclusions It can be concluded that the back of the tongue plays an important role in the oral resorption of drugs. Clinical relevance: The results may be of relevance for the delivery and development of oral drug application. PMID:23497446

2013-01-01

30

Induction of Pancreatic Differentiation by Signals from Blood Vessels  

NASA Astrophysics Data System (ADS)

Blood vessels supply developing organs with metabolic sustenance. Here, we demonstrate a role for blood vessels as a source of developmental signals during pancreatic organogenesis. In vitro experiments with embryonic mouse tissues demonstrate that blood vessel endothelium induces insulin expression in isolated endoderm. Removal of the dorsal aorta in Xenopus laevis embryos results in the failure of insulin expression in vivo. Furthermore, using transgenic mice, we show that ectopic vascularization in the posterior foregut leads to ectopic insulin expression and islet hyperplasia. These results indicate that vessels not only provide metabolic sustenance, but also provide inductive signals for organ development.

Lammert, Eckhard; Cleaver, Ondine; Melton, Douglas

2001-10-01

31

The fine structure of cephalopod blood vessels II. The vessels of the nervous system  

Microsoft Academic Search

Blood vessels of the perioesophageal nerve ganglia (brain) of Octopus vulgaris and the stellate ganglia of Sepia officinalis are described. The vessels have an incomplete endothelium, a complete basement membrane and a complete investment of pericytes. The pericytes are joined by specialised membrane junctions but these are not tight junctions. The main type of neuron\\/vessel arrangement is one where there

V. C. Barber; P. Graziadei

1967-01-01

32

Bridging mucosal vessels associated with rhythmically oscillating blood flow in murine colitis.  

PubMed

Oscillatory blood flow in the microcirculation is generally considered to be the result of cardiopulmonary influences or active vasomotion. In this report, we describe rhythmically oscillating blood flow in the bridging vessels of the mouse colon that appeared to be independent of known biological control mechanisms. Corrosion casting and scanning electron microscopy of the mouse colon demonstrated highly branched bridging vessels that connected the submucosal vessels with the mucosal plexus. Because of similar morphometric characteristics (19 +/- 11 microm vs. 28 +/- 16 microm), bridging arterioles and venules were distinguished by tracking fluorescent nanoparticles through the microcirculation using intravital fluorescence videomicroscopy. In control mice, the blood flow through the bridging vessels was typically continuous and unidirectional. In contrast, two models of chemically induced inflammation (trinitrobenzenesulfonic acid and dextran sodium sulfate) were associated with a twofold reduction in flow velocity and the prominence of rhythmically oscillating blood flow. The blood oscillation was characterized by tracking the bidirectional displacement of fluorescent nanoparticles. Space-time plots and particle tracking of the oscillating segments demonstrated an oscillation frequency between 0.2 and 5.1 cycles per second. Discrete Fourier transforms demonstrated a power spectrum composed of several base frequencies. These observations suggest that inflammation-inducible changes in blood flow patterns in the murine colon resulted in both reduced blood flow velocity and rhythmic oscillations within the bridging vessels of the mouse colon. PMID:18085623

Turhan, Aslihan; Konerding, Moritz A; Tsuda, Akira; Ravnic, Dino J; Hanidziar, Dusan; Lin, Miao; Mentzer, Steven J

2008-01-01

33

Simulation of Blood Flow at Vessel Bifurcation by Lattice Boltzmann Method  

NASA Astrophysics Data System (ADS)

The application of the lattice Boltzmann method to the large vessel bifurcation blood flow is investigated in a wide range of Reynolds numbers. The velocity, shear stress and pressure distributions at the bifurcation are presented in detail. The flow separation zones revealed with increase of Reynolds number are located in the areas of the daughter branches distal to the outer corners of the bifurcation where some deposition of particular blood components might occur to form arteriosclerosis. The results also demonstrate that the lattice Boltzmann method is adaptive to simulating the flow in larger vessels under a high Reynolds number.

Kang, Xiu-Ying; Liu, Da-He; Zhou, Jing; Jin, Yong-Juan

2005-11-01

34

Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides  

SciTech Connect

At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No penetration of the radionuclide into the blood vessel was assumed nor was cross fire between the vessel assumed. The results are useful in assessing the dose to blood and blood vessel walls for different nuclear medicine procedures.

Akabani, G.; Poston, J.W. Sr. (Texas A M Univ., College Station (USA))

1991-05-01

35

Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides  

SciTech Connect

At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No diffusion of the radionuclide into the blood vessel was assumed nor cross fire between vessel was assumed. Results are useful in assessing the dose in blood and blood vessel walls for different nuclear medicine procedures. 6 refs., 6 figs., 5 tabs.

Akabani, G. (Pacific Northwest Lab., Richland, WA (USA)); Poston, J.W. (Texas A and M Univ., College Station, TX (USA). Dept. of Nuclear Engineering)

1991-05-01

36

Topological imaging of blood vessels by using diffusing light  

NASA Astrophysics Data System (ADS)

The topographic imaging technique using a backscattered diffusing light is proposed to monitor dynamics of blood vessels depending on the blood flow as a noncontact and noninvasive method. Their depth in skin tissues can be estimated by using the relation between a spatially-integrated backscattered intensity and a probability density function of an optical path-length. The topological image of the blood vessels is obtained per 0.08 sec by the developed system.

Kohama, Shotaro; Iwai, Toshiaki

2014-08-01

37

Glucose metabolism in diabetic blood vessels  

SciTech Connect

Since glycolysis appears to be coupled to active ion transport in vascular smooth muscle, alterations in glucose metabolism may contribute to cellular dysfunction and angiopathy in diabetes. Uptake and utilization of glucose were studied in perfused blood vessels in which pulsatile flow and perfusion pressure were similar to those measured directly in vivo. Thoracic aortae isolated from 8-wk alloxan diabetic (D) and nondiabetic control rabbits were cannulated, tethered, and perfused with oxygenated buffer containing 7 or 25 mM glucose and tracer amounts of glucose-U/sup -14/ C. Norepinephrine (NE) (10/sup -6/ M) and/or insulin (I) (150 ..mu..U/ml) and albumin (0.2%) were added. NE-induced tension development increased glucose uptake 39% and /sup 14/CO/sub 2/ and lactate production 2.3-fold. With 7 mM glucose, marked decreases in glucose uptake (74%), /sup 14/CO/sub 2/ (68%), lactate (30%), total tissue glycogen (75%), and tissue phospholipids (70%) were observed in D. Addition of I or elevation of exogenous glucose to 25 mM normalized glucose uptake, but had differential effects on the pattern of substrate utilization. Thus, in D, there was a marked depression of vascular glucose metabolism that was partially reversed by addition of low concentrations of insulin or D levels of glucose.

Brown, B.J.; Crass, M.F. III

1986-03-05

38

Large Blood Vessels 1.1 Introduction --The Cardiovascular System  

E-print Network

Chapter 1 Large Blood Vessels 1.1 Introduction -- The Cardiovascular System The heart is a pump that circulates blood to the lungs for oxygenation (pul- monary circulation) and then throughout the systemic arterial system with a total cycle time of about one minute. From the left ventricle of the heart, blood

Luo, Xiaoyu

39

Blood Vessels of the Fetal Pig Dissection Anterior Vessels Protocol  

E-print Network

and right internal jugulars, next to them are the left and right external jugulars. Outside the external and going to each shoulder are the subscapulars. d. Trace the external jugulars up to the point where, running along the back of each jaw toward the ear. e. The right and left internal mammary veins branch off

Loughry, Jim

40

Selective photocoagulation of cutaneous blood vessels: evaluation of vessel damage by color Doppler optical coherence tomography  

NASA Astrophysics Data System (ADS)

This study investigates the threshold radiant exposures required to irreversibly damage cutaneous blood vessels using a pulsed dye laser (PDL) operating at 585 nm. Evaluation of blood vessel damage and blood flow stoppage was achieved using Doppler imaging in a color Doppler optical coherence tomographic (CDOCT) system. Hamster dorsal skin flap window vessels were irradiated with radiant exposures ranging from 2.5 - 8 J/cm2. A 5 mm spot size and 360 microsecond pulse duration were used. Irradiation sites were imaged with CDOCT prior to, immediately after, and a minimum of 24 hours after delivery of laser energy. Magnitude and color Doppler images provided information such as approximate vessel size, depth, and changes in blood flow velocity. Vessel stenosis, temporary occlusion, permanent occlusion, hemorrhaging, and changes in flow velocity were frequent results of laser irradiation visualized with CDOCT and video imaging. Probit analysis was used to estimate the 50% probability that a blood vessel of given size and type will be destroyed by a given radiant exposure. In most instances, arterioles required higher radiant exposures to be irreversibly damaged than venules of the same size. However, arteriole/venule pairs required approximately the same radiant exposures for visible damage to occur. Vessels of larger diameter required higher radiant exposures to coagulate than vessels of smaller diameter.

Vargas, Gracie; Ducros, Mathieu G.; Dozier, Susan; Barton, Jennifer K.; Welch, Ashley J.

2000-05-01

41

Development of blood vessel searching system for HMS  

NASA Astrophysics Data System (ADS)

In this study, we develop a new 3D miniature blood vessel searching system by using near-infrared LED light, a CMOS camera module with an image processing unit for a health monitoring system (HMS), a drug delivery system (DDS) which requires very high performance for automatic micro blood volume extraction and automatic blood examination. Our objective is to fabricate a highly reliable micro detection system by utilizing image capturing, image processing, and micro blood extraction devices. For the searching system to determine 3D blood vessel location, we employ the stereo method. The stereo method is a common photogrammetric method. It employs the optical path principle to detect 3D location of the disparity between two cameras. The principle for blood vessel visualization is derived from the ratio of hemoglobin's absorption of the near-infrared LED light. To get a high quality blood vessel image, we adopted an LED, with peak a wavelength of 940nm. The LED is set on the dorsal side of the finger and it irradiates the human finger. A blood vessel image is captured by a CMOS camera module, which is set below the palmer side of the finger. 2D blood vessel location can be detected by the luminance distribution of a one pixel line. To examine the accuracy of our detecting system, we carried out experiments using finger phantoms with blood vessel diameters of 0.5, 0.75, 1.0mm, at the depths of 0.5 ~ 2.0 mm from the phantom's surface. The experimental results of the estimated depth obtained by our detecting system shows good agreements with the given depths, and the viability of this system is confirmed.

Kandani, Hirofumi; Uenoya, Toshiyuki; Uetsuji, Yasutomo; Nakamachi, Eiji

2008-08-01

42

Computer Analysis of Eye Blood-Vessel Images  

NASA Technical Reports Server (NTRS)

Technique rapidly diagnoses diabetes mellitus. Photographs of "whites" of patients' eyes scanned by computerized image analyzer programmed to quantify density of small blood vessels in conjuctiva. Comparison with data base of known normal and diabetic patients facilitates rapid diagnosis.

Wall, R. J.; White, B. S.

1984-01-01

43

Extraction of retinal blood vessels by curvelet transform  

Microsoft Academic Search

This paper presents an efficient method for automatic extraction of blood vessels in retinal images to improve the detection of low contrast and narrow vessels. The proposed algorithm is composed of four steps: curvelet-based contrast enhancement, match filtering, curvelet-based edge extraction, and length filtering. In this base, after reconstruction of enhanced image from the modified curvelet coefficients, match filtering is

Mahdad Esmaeili; Hossein Rabbani; Alireza Mehri; Alireza Dehghani

2009-01-01

44

Improvement of retinal blood vessel detection using morphological component analysis.  

PubMed

Detection and quantitative measurement of variations in the retinal blood vessels can help diagnose several diseases including diabetic retinopathy. Intrinsic characteristics of abnormal retinal images make blood vessel detection difficult. The major problem with traditional vessel segmentation algorithms is producing false positive vessels in the presence of diabetic retinopathy lesions. To overcome this problem, a novel scheme for extracting retinal blood vessels based on morphological component analysis (MCA) algorithm is presented in this paper. MCA was developed based on sparse representation of signals. This algorithm assumes that each signal is a linear combination of several morphologically distinct components. In the proposed method, the MCA algorithm with appropriate transforms is adopted to separate vessels and lesions from each other. Afterwards, the Morlet Wavelet Transform is applied to enhance the retinal vessels. The final vessel map is obtained by adaptive thresholding. The performance of the proposed method is measured on the publicly available DRIVE and STARE datasets and compared with several state-of-the-art methods. An accuracy of 0.9523 and 0.9590 has been respectively achieved on the DRIVE and STARE datasets, which are not only greater than most methods, but are also superior to the second human observer's performance. The results show that the proposed method can achieve improved detection in abnormal retinal images and decrease false positive vessels in pathological regions compared to other methods. Also, the robustness of the method in the presence of noise is shown via experimental result. PMID:25697986

Imani, Elaheh; Javidi, Malihe; Pourreza, Hamid-Reza

2015-03-01

45

A novel method for blood vessel detection from retinal images  

PubMed Central

Background The morphological changes of the retinal blood vessels in retinal images are important indicators for diseases like diabetes, hypertension and glaucoma. Thus the accurate segmentation of blood vessel is of diagnostic value. Methods In this paper, we present a novel method to segment retinal blood vessels to overcome the variations in contrast of large and thin vessels. This method uses adaptive local thresholding to produce a binary image then extract large connected components as large vessels. The residual fragments in the binary image including some thin vessel segments (or pixels), are classified by Support Vector Machine (SVM). The tracking growth is applied to the thin vessel segments to form the whole vascular network. Results The proposed algorithm is tested on DRIVE database, and the average sensitivity is over 77% while the average accuracy reaches 93.2%. Conclusions In this paper, we distinguish large vessels by adaptive local thresholding for their good contrast. Then identify some thin vessel segments with bad contrast by SVM, which can be lengthened by tracking. This proposed method can avoid heavy computation and manual intervention. PMID:20187975

2010-01-01

46

Development of a blood vessel searching device for HMS  

NASA Astrophysics Data System (ADS)

In this study, an automatic blood vessel searching system (BVSS) is newly developed, which is built in the health monitoring system (HMS) and the drug delivery system (DDS) to extract the blood, evaluates the blood sugar level and injects the insulin for the diabetic patients. Main subjects of our BVSS development are 1) a transmittance photo imaging of the finger by using the LED light as a near-infrared light source with peak wave length of 870 nm, and 2) an image processing to detect the location of the center of the blood vessel cross section. The sharp edge focus method was applied in our BVSS to detect the depth of blood vessel. We carried out experiments by using blood vessel phantoms, which consist of an artificial cylindrical blood vessel and skin tissue, which are made of the teflon tube and the silicone rubber. The teflon tube has the size of 0.6 mm in diameter and is filled with the human blood. The experimental results demonstrated that the estimated depth, which is obtained by image analysis corresponding to given depths, shows a good agreement with the real values, and consequently the availability of our BVSS is confirmed.

Kuroda, Tatsuro; Uenoya, Toshiyuki; Tsuchiya, Kazuyoshi; Uetsuji, Yasutomo; Nakamachi, Eiji

2007-12-01

47

Invasive Electrical Impedance Tomography for Blood Vessel Detection  

PubMed Central

We present a novel method for localization of large blood vessels using a bioimpedance based needle positioning system on an array of ten monopolar needle electrodes. The purpose of the study is to develop a portable, low cost tool for rapid vascular access for cooling and controlled reperfusion of cardiac arrest patients. Preliminary results show that localization of blood vessels is feasible with this method, but larger studies are necessary to improve the technology. PMID:21611140

Martinsen, rjan G.; Kalvy, Hvard; Grimnes, Sverre; Nordbotten, Bernt; Hol, Per Kristian; Fosse, Erik; Myklebust, Helge; Becker, Lance B

2010-01-01

48

Analysis of Blood Flow in a Partially Blocked Bifurcated Blood Vessel  

NASA Astrophysics Data System (ADS)

Coronary artery disease is a major cause of death in the United States. It is the narrowing of the lumens of the coronary blood vessel by a gradual build-up of fatty material, atheroma, which leads to the heart muscle not receiving enough blood. This my ocardial ischemia can cause angina, a heart attack, heart failure as well as sudden cardiac death [9]. In this project a solid model of bifurcated blood vessel with an asymmetric stenosis is developed using GAMBIT and imported into FLUENT for analysis. In FLUENT, pressure and velocity distributions in the blood vessel are studied under different conditions, where the size and position of the blockage in the blood vessel are varied. The location and size of the blockage in the blood vessel are correlated with the pressures and velocities distributions. Results show that such correlation may be used to predict the size and location of the blockage.

Abdul-Razzak, Hayder; Elkassabgi, Yousri; Punati, Pavan K.; Nasser, Naseer

2009-09-01

49

Sausage-string deformations of blood vessels at high blood pressures  

NASA Astrophysics Data System (ADS)

A new instability is proposed to explain the sausage-string patterns of alternating constrictions and dilatations formed in blood vessels at high blood pressure conditions. Our theory provides predictions for the conditions under which the cylindrical geometry of a blood vessel becomes unstable. The theory is related to experimental observations in rats, where high blood pressure is induced by intravenous infusion of angiotensin II.

Alstrm, P.; Mikkelsen, R.; Gustafsson, F.; Holstein-Rathlou, N.-H.

1999-12-01

50

SIRT1 - a metabolic sensor that controls blood vessel growth.  

PubMed

Blood vessels deliver nutrients and oxygen to cells and tissues in the body. When blood supply is insufficient new vessels form to meet the metabolic tissue requirements. Several studies have examined the cellular and molecular principles of blood vessel formation, yet little is known about how vessels sense and integrate environmental signals originating from nutrient- and oxygen-deprived tissues to achieve functional vascular patterning. The NAD(+)-dependent deacetylase SIRT1 mediates adaptation to environmental stresses by adjusting cellular responses to the energetic state of the cell and recent studies highlight important functions of SIRT1 in regulating vascular growth, shape, and function. Here, we review the emerging role of SIRT1 as a metabolic sensor coupling energy and oxygen homeostasis to the growth and function of the vasculature. PMID:20149740

Guarani, Virginia; Potente, Michael

2010-04-01

51

Integrin ?1 controls VE-cadherin localization and blood vessel stability.  

PubMed

Angiogenic blood vessel growth requires several distinct but integrated cellular activities. Endothelial cell sprouting and proliferation lead to the expansion of the vasculature and give rise to a highly branched, immature plexus, which is subsequently reorganized into a mature and stable network. Although it is known that integrin-mediated cell-matrix interactions are indispensable for embryonic angiogenesis, little is known about the function of integrins in different steps of vascular morphogenesis. Here, by investigating the integrin ?1-subunit with inducible and endothelial-specific gene targeting in the postnatal mouse retina, we show that ?1 integrin promotes endothelial sprouting but is a negative regulator of proliferation. In maturing vessels, integrin ?1 is indispensable for proper localization of VE-cadherin and thereby cell-cell junction integrity. The sum of our findings establishes that integrin ?1 has critical functions in the growing and maturing vasculature, and is required for the formation of stable, non-leaky blood vessels. PMID:25752958

Yamamoto, Hiroyuki; Ehling, Manuel; Kato, Katsuhiro; Kanai, Kenichi; van Lessen, Max; Frye, Maike; Zeuschner, Dagmar; Nakayama, Masanori; Vestweber, Dietmar; Adams, Ralf H

2015-01-01

52

Allogeneic human tissue-engineered blood vessel  

PubMed Central

Background Arterial bypass graft implantation remains the primary therapy for patients with advanced cardiovascular disease; however, there is no available synthetic small-diameter vascular graft. Methods Tissue-engineered vessels were grown from human smooth muscle cells that were seeded on a biodegradable scaffold using a biomimetic perfusion system. The human tissue-engineered vessels (hTEV) were decellularized by a two-step process using a combination of detergents and hypertonic solutions. The mechanical characteristics were assessed by suture retention strength and burst pressure. The decellularized hTEV were implanted as aortic interpositional grafts in nude rats to evaluate in vivo performance as an arterial graft over a 6-week period. Results The human tissue-engineered structure formed a vessel composed of smooth muscle cells and the extracellular matrix proteins, including collagen. After decellularization, the collagen matrix remained intact while the cellular components were removed. The mechanical strength of the hTEV after decellularization was similar to human vein in vitro, with a burst pressure of 1,567 384 mm Hg (n = 3) versus 1,680 307 mm Hg for human saphenous vein. The hTEVs had a high patency rate (four of five grafts) without evidence of rupture or aneurysm over a 6-week period as an aortic interpositional graft in a nude rat model. Histologic analysis showed a thin neointima with a confluent endothelium and a subendothelial layer of smooth muscle cells on the explanted tissue-engineered vessels. Transmission electron microscopy on the explanted tissue demonstrated elastin formation in the neointima and intact residual collagen fibers from the tissue-engineered vessel. Conclusions The hTEV had a high patency rate and remained mechanically stable as an aortic interpositional graft in a nude rat. The vessel supported the growth of a neointima with endothelial cells and smooth muscle cells. The host remodeling suggested the engineered matrix had a positive effect to create a regenerated vascular graft. PMID:22056286

Quint, Clay; Arief, Melissa; Muto, Akihito; Dardik, Alan; Niklason, Laura E.

2012-01-01

53

Integration of Repulsive Guidance Cues Generates Avascular Zones that Shape Mammalian Blood Vessels  

PubMed Central

Rationale Positive signals, such as vascular endothelial factor (VEGF), direct endothelial cells (ECs) to specific locations during blood vessel formation. Less is known about repulsive signal contribution to shaping vessels. Recently, neuronal guidance cues (NGCs) have been shown to influence EC behavior, particularly in directing sprouting angiogenesis by repelling ECs. However, their role during de novo blood vessel formation remains unexplored. Objective To identify signals that guide and pattern the first mammalian blood vessels. Methods and Results Using genetic mouse models, we show that blood vessels are sculpted via the generation of stereotyped avascular zones by EC-repulsive cues. We demonstrate that Semaphorin3E (Sema3E) is a key factor that shapes the paired DA in mouse, as sema3E-/- embryos develop an abnormally branched aortic plexus with a markedly narrowed avascular midline. In vitro cultures and avian grafting experiments show strong repulsion of ECs by Sema3E-expressing cells. We further identify the mouse notochord as a rich source of multiple redundant NGCs. Mouse embryos that lack notochords fail to form cohesive aortic vessels due to loss of the avascular midline, yet maintain lateral avascular zones. We demonstrate that lateral avascular zones are directly generated by the lateral plate mesoderm (LPM), a critical source of Sema3E. Conclusions These findings demonstrate that Sema3E-generated avascular zones are critical regulators of mammalian cardiovascular patterning, and are the first to identify a repulsive role for the LPM. Integration of multiple, and in some cases redundant, repulsive cues from various tissues is critical to patterning the first embryonic blood vessels. PMID:22076636

Meadows, Stryder M.; Fletcher, Peter J.; Moran, Carlos; Xu, Ke; Neufeld, Gera; Chauvet, Sophie; Mann, Fanny; Krieg, Paul; Cleaver, Ondine

2011-01-01

54

Blood Vessel Adaptation with Fluctuations in Capillary Flow Distribution  

PubMed Central

Throughout the life of animals and human beings, blood vessel systems are continuously adapting their structures the diameter of vessel lumina, the thickness of vessel walls, and the number of micro-vessels to meet the changing metabolic demand of the tissue. The competition between an ever decreasing tendency of luminal diameters and an increasing stimulus from the wall shear stress plays a key role in the adaptation of luminal diameters. However, it has been shown in previous studies that the adaptation dynamics based only on these two effects is unstable. In this work, we propose a minimal adaptation model of vessel luminal diameters, in which we take into account the effects of metabolic flow regulation in addition to wall shear stresses and the decreasing tendency of luminal diameters. In particular, we study the role, in the adaptation process, of fluctuations in capillary flow distribution which is an important means of metabolic flow regulation. The fluctuation in the flow of a capillary group is idealized as a switch between two states, i.e., an open-state and a close-state. Using this model, we show that the adaptation of blood vessel system driven by wall shear stress can be efficiently stabilized when the open time ratio responds sensitively to capillary flows. As micro-vessel rarefaction is observed in our simulations with a uniformly decreased open time ratio of capillary flows, our results point to a possible origin of micro-vessel rarefaction, which is believed to induce hypertension. PMID:23029014

Hu, Dan; Cai, David; Rangan, Aaditya V.

2012-01-01

55

What Determines Blood Vessel Structure? Genetic Prespecification vs. Hemodynamics  

NSDL National Science Digital Library

Vascular network remodeling, angiogenesis, and arteriogenesis play an important role in the pathophysiology of ischemic cardiovascular diseases and cancer. Based on recent studies of vascular network development in the embryo, several novel aspects to angiogenesis have been identified as crucial to generate a functional vascular network. These aspects include specification of arterial and venous identity in vessels and network patterning. In early embryogenesis, vessel identity and positioning are genetically hardwired and involve neural guidance genes expressed in the vascular system. We demonstrated that, during later stages of embryogenesis, blood flow plays a crucial role in regulating vessel identity and network remodeling. The flow-evoked remodeling process is dynamic and involves a high degree of vessel plasticity. The open question in the field is how genetically predetermined processes in vessel identity and patterning balance with the contribution of blood flow in shaping a functional vascular architecture. Although blood flow is essential, it remains unclear to what extent flow is able to act on the developing cardiovascular system. There is significant evidence that mechanical forces created by flowing blood are biologically active within the embryo and that the level of mechanical forces and the type of flow patterns present in the embryo are able to affect gene expression. Here, we highlight the pivotal role for blood flow and physical forces in shaping the cardiovascular system.

Elizabeth A. V. Jones (College de France)

2006-10-01

56

Brain blood vessel segmentation using line-shaped profiles  

NASA Astrophysics Data System (ADS)

Segmentation of cerebral blood vessels is of great importance in diagnostic and clinical applications, especially for embolization of cerebral aneurysms and arteriovenous malformations (AVMs). In order to perform embolization of the AVM, the structural and geometric information of blood vessels from 3D images is of utmost importance. For this reason, the in-depth segmentation of cerebral blood vessels is usually done as a fusion of different segmentation techniques, often requiring extensive user interaction. In this paper we introduce the idea of line-shaped profiling with an application to brain blood vessel and AVM segmentation, efficient both in terms of resolving details and in terms of computation time. Our method takes into account both local proximate and wider neighbourhood of the processed pixel, which makes it efficient for segmenting large blood vessel tree structures, as well as fine structures of the AVMs. Another advantage of our method is that it requires selection of only one parameter to perform segmentation, yielding very little user interaction.

Babin, Danilo; Piurica, Aleksandra; De Vylder, Jonas; Vansteenkiste, Ewout; Philips, Wilfried

2013-11-01

57

Angle-preserving mappings for the visualization of multi-branched vessels  

Microsoft Academic Search

In this note, we employ a conformal mapping technique to flatten tubular structures with multi-branches for visualiza- tion of MRA and CT volumetric vessel imagery. This may be used for the study of possible vessel pathology or virtual colonscopy for polyp detection. The method is based on a discrete Laplace-Beltrami operator to flatten a tubular sur- face onto a planar

Lei Zhu; Steven Haker; Sylvain Bouix; Kaleem Siddiqi; Allen Tannenbaum

2002-01-01

58

A systems biology view of blood vessel growth and remodelling  

PubMed Central

Blood travels throughout the body in an extensive network of vessels arteries, veins and capillaries. This vascular network is not static, but instead dynamically remodels in response to stimuli from cells in the nearby tissue. In particular, the smallest vessels arterioles, venules and capillaries can be extended, expanded or pruned, in response to exercise, ischaemic events, pharmacological interventions, or other physiological and pathophysiological events. In this review, we describe the multi-step morphogenic process of angiogenesis the sprouting of new blood vessels and the stability of vascular networks in vivo. In particular, we review the known interactions between endothelial cells and the various blood cells and plasma components they convey. We describe progress that has been made in applying computational modelling, quantitative biology and high-throughput experimentation to the angiogenesis process. PMID:24237862

Logsdon, Elizabeth A; Finley, Stacey D; Popel, Aleksander S; Gabhann, Feilim Mac

2014-01-01

59

Crosstalk between the developing pancreas and its blood vessels: an evolving dialogue  

PubMed Central

Growth and development of embryonic organs goes hand in hand with development of the vascular system. Blood vessels have been known for centuries to supply nutrients and oxygen to all cell types in an organism, however, they have more recently been shown to provide specific cues required for the formation and functionality of a number of tissues. Here, we review the role of blood vessels during pancreas formation, from early specification of the initial pancreatic bud, to its growth and maturation. The overarching theme that emerges from the many studies carried out in the past decade is that the vasculature likely plays diverse and changing roles during pancreas organogenesis. Blood vessels are required for endocrine specification at the onset of pancreatic budding, while only a few days later, blood vessels suppress pancreatic branching and exocrine differentiation. In this review, we summarize our understanding to date about the crosstalk between the pancreas and its vasculature, and we provide a perspective on the promises and challenges of the field. PMID:22728668

Villasenor, Alethia; Cleaver, Ondine

2015-01-01

60

Blood Vessel Segmentation of Fundus Images by Major Vessel Extraction and Sub-Image Classification.  

PubMed

This paper presents a novel three-stage blood vessel segmentation algorithm using fundus photographs. In the first stage, the green plane of a fundus image is pre-processed to extract a binary image after high-pass filtering, and another binary image from the morphologically reconstructed enhanced image for the vessel regions. Next, the regions common to both the binary images are extracted as the major vessels. In the second stage, all remaining pixels in the two binary images are classified using a Gaussian Mixture Model (GMM) classifier using a set of 8 features that are extracted based on pixel neighborhood and first and second-order gradient images. In the third post-processing stage, the major portions of the blood vessels are combined with the classified vessel pixels. The proposed algorithm is less dependent on training data, requires less segmentation time and achieves consistent vessel segmentation accuracy on normal images as well as images with pathology when compared to existing supervised segmentation methods. The proposed algorithm achieves a vessel segmentation accuracy of 95.2%, 95.15% and 95.3% in an average of 3.1 seconds, 6.7 seconds and 11.7 seconds on three public data sets DRIVE, STARE, and CHASE DB1, respectively. PMID:25014980

Roychowdhury, Sohini; Koozekanani, Dara; Parhi, Keshab

2014-07-01

61

Acrolein generation stimulates hypercontraction in isolated human blood vessels  

SciTech Connect

Increased risk of vasospasm, a spontaneous hyperconstriction, is associated with atherosclerosis, cigarette smoking, and hypertension-all conditions involving oxidative stress, lipid peroxidation, and inflammation. To test the role of the lipid peroxidation- and inflammation-derived aldehyde, acrolein, in human vasospasm, we developed an ex vivo model using human coronary artery bypass graft (CABG) blood vessels and a demonstrated acrolein precursor, allylamine. Allylamine induces hypercontraction in isolated rat coronary artery in a semicarbazide-sensitive amine oxidase activity (SSAO) dependent manner. Isolated human CABG blood vessels (internal mammary artery, radial artery, saphenous vein) were used to determine: (1) vessel responses and sensitivity to acrolein, allylamine, and H{sub 2}O{sub 2} exposure (1 {mu}M-1 mM), (2) SSAO dependence of allylamine-induced effects using SSAO inhibitors (semicarbazide, 1 mM; MDL 72274-E, active isomer; MDL 72274-Z, inactive isomer; 100 {mu}M), (3) the vasoactive effects of two other SSAO amine substrates, benzylamine and methylamine, and (4) the contribution of extracellular Ca{sup 2+} to hypercontraction. Acrolein or allylamine but not H{sub 2}O{sub 2}, benzylamine, or methylamine stimulated spontaneous and pharmacologically intractable hypercontraction in CABG blood vessels that was similar to clinical vasospasm. Allylamine-induced hypercontraction and blood vessel SSAO activity were abolished by pretreatment with semicarbazide or MDL 72274-E but not by MDL 72274-Z. Allylamine-induced hypercontraction also was significantly attenuated in Ca{sup 2+}-free buffer. In isolated aorta of spontaneously hypertensive rat, allylamine-induced an SSAO-dependent contraction and enhanced norepinephrine sensitivity but not in Sprague-Dawley rat aorta. We conclude that acrolein generation in the blood vessel wall increases human susceptibility to vasospasm, an event that is enhanced in hypertension.

Conklin, D.J. [Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY 40202 (United States) and Department of Biology, University of Wisconsin-Eau Claire, Eau Claire, WI 54701 (United States)]. E-mail: dj.conklin@louisville.edu; Bhatnagar, A. [Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY 40202 (United States); Cowley, H.R. [Department of Biology, University of Wisconsin-Eau Claire, Eau Claire, WI 54701 (United States); Johnson, G.H. [Department of Cardiothoracic Surgery, Luther Hospital/Midelfort Clinic, Eau Claire, WI 54702 (United States); Wiechmann, R.J. [Department of Cardiothoracic Surgery, Luther Hospital/Midelfort Clinic, Eau Claire, WI 54702 (United States); Sayre, L.M. [Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106 (United States); Trent, M.B. [Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555-0609 (United States); Boor, P.J. [Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555-0609 (United States)

2006-12-15

62

[Topography of the blood vessels in the hilum of the kidney of Myrmecophaga tridactyla].  

PubMed

The study was undertaken in 10 formol-imbibed kidneys of great anteater (Myrmecophaga tridactyla). After the dissection the following characteristics were showed: kidney blood vessels are distributed in 2 different sites, namely hilar and extrahilar, amounting 3 to 6 in the right side 3 to 7 in the left side. Arterial branches in extrahilar region range from 1 to 2 in both sides and in hilar region they present from 1 to 4 in the right and 1 to 2 in the left. Venous roots occur in 1 to 2 vessels in the right and 1 to 3 vessels in the left, occupying only the hilar region, except one case where it was present in the right side. PMID:1952090

Souza, W M; Miglino, M A; Arantes, I G; Nascimento, A A

1991-01-01

63

On the adaptive detection of blood vessels in retinal images.  

PubMed

This paper proposes an automated blood vessel detection scheme based on adaptive contrast enhancement, feature extraction, and tracing. Feature extraction of small blood vessels is performed by using the standard deviation of Gabor filter responses. Tracing of vessels is done via forward detection, bifurcation identification, and backward verification. Tests over twenty images show that for normal images, the true positive rate (TPR) ranges from 80% to 91%, and their corresponding false positive rates (FPR) range from 2.8% to 5.5%. For abnormal images, the TPR ranges from 73.8% to 86.5% and the FPR ranges from 2.1% to 5.3%, respectively. In comparison with two published solution schemes that were also based on the STARE database, our scheme has lower FPR for the reported TPR measure. PMID:16485764

Wu, Di; Zhang, Ming; Liu, Jyh-Charn; Bauman, Wendall

2006-02-01

64

Wavelength dependence of the apparent diameter of retinal blood vessels  

NASA Astrophysics Data System (ADS)

Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column.

Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

2005-04-01

65

Fractal structures in stenoses and aneurysms in blood vessels  

PubMed Central

Recent advances in the field of chaotic advection provide the impetus to revisit the dynamics of particles transported by blood flow in the presence of vessel wall irregularities. The irregularity, being either a narrowing or expansion of the vessel, mimicking stenoses or aneurysms, generates abnormal flow patterns that lead to a peculiar filamentary distribution of advected particles, which, in the blood, would include platelets. Using a simple model, we show how the filamentary distribution depends on the size of the vessel wall irregularity, and how it varies under resting or exercise conditions. The particles transported by blood flow that spend a long time around a disturbance either stick to the vessel wall or reside on fractal filaments. We show that the faster flow associated with exercise creates widespread filaments where particles can get trapped for a longer time, thus allowing for the possible activation of such particles. We argue, based on previous results in the field of active processes in flows, that the non-trivial long-time distribution of transported particles has the potential to have major effects on biochemical processes occurring in blood flow, including the activation and deposition of platelets. One aspect of the generality of our approach is that it also applies to other relevant biological processes, an example being the coexistence of plankton species investigated previously. PMID:21078637

Schelin, Adriane B.; Krolyi, Gyrgy; de Moura, Alessandro P. S.; Booth, Nuala A.; Grebogi, Celso

2010-01-01

66

Fractal structures in stenoses and aneurysms in blood vessels.  

PubMed

Recent advances in the field of chaotic advection provide the impetus to revisit the dynamics of particles transported by blood flow in the presence of vessel wall irregularities. The irregularity, being either a narrowing or expansion of the vessel, mimicking stenoses or aneurysms, generates abnormal flow patterns that lead to a peculiar filamentary distribution of advected particles, which, in the blood, would include platelets. Using a simple model, we show how the filamentary distribution depends on the size of the vessel wall irregularity, and how it varies under resting or exercise conditions. The particles transported by blood flow that spend a long time around a disturbance either stick to the vessel wall or reside on fractal filaments. We show that the faster flow associated with exercise creates widespread filaments where particles can get trapped for a longer time, thus allowing for the possible activation of such particles. We argue, based on previous results in the field of active processes in flows, that the non-trivial long-time distribution of transported particles has the potential to have major effects on biochemical processes occurring in blood flow, including the activation and deposition of platelets. One aspect of the generality of our approach is that it also applies to other relevant biological processes, an example being the coexistence of plankton species investigated previously. PMID:21078637

Schelin, Adriane B; Krolyi, Gyrgy; de Moura, Alessandro P S; Booth, Nuala A; Grebogi, Celso

2010-12-28

67

Gene expression analysis in human breast cancer associated blood vessels.  

PubMed

Angiogenesis is essential for solid tumour growth, whilst the molecular profiles of tumour blood vessels have been reported to be different between cancer types. Although presently available anti-angiogenic strategies are providing some promise for the treatment of some cancers it is perhaps not surprisingly that, none of the anti-angiogenic agents available work on all tumours. Thus, the discovery of novel anti-angiogenic targets, relevant to individual cancer types, is required. Using Affymetrix microarray analysis of laser-captured, CD31-positive blood vessels we have identified 63 genes that are upregulated significantly (5-72 fold) in angiogenic blood vessels associated with human invasive ductal carcinoma (IDC) of the breast as compared with blood vessels in normal human breast. We tested the angiogenic capacity of a subset of these genes. Genes were selected based on either their known cellular functions, their enriched expression in endothelial cells and/or their sensitivity to anti-VEGF treatment; all features implicating their involvement in angiogenesis. For example, RRM2, a ribonucleotide reductase involved in DNA synthesis, was upregulated 32-fold in IDC-associated blood vessels; ATF1, a nuclear activating transcription factor involved in cellular growth and survival was upregulated 23-fold in IDC-associated blood vessels and HEX-B, a hexosaminidase involved in the breakdown of GM2 gangliosides, was upregulated 8-fold in IDC-associated blood vessels. Furthermore, in silico analysis confirmed that AFT1 and HEX-B also were enriched in endothelial cells when compared with non-endothelial cells. None of these genes have been reported previously to be involved in neovascularisation. However, our data establish that siRNA depletion of Rrm2, Atf1 or Hex-B had significant anti-angiogenic effects in VEGF-stimulated ex vivo mouse aortic ring assays. Overall, our results provide proof-of-principle that our approach can identify a cohort of potentially novel anti-angiogenic targets that are likley to be, but not exclusivley, relevant to breast cancer. PMID:23056178

Jones, Dylan T; Lechertier, Tanguy; Mitter, Richard; Herbert, John M J; Bicknell, Roy; Jones, J Louise; Li, Ji-Liang; Buffa, Francesca; Harris, Adrian L; Hodivala-Dilke, Kairbaan

2012-01-01

68

Age, Blood Pressure, and Retinal Vessel Diameter: Separate Effects and Interaction of Blood Pressure and Age  

Microsoft Academic Search

PURPOSE. The association of age and blood pressure (BP) with retinal vessel change is widely reported, with inverse relation- ships between retinal arteriolar and venular diameter and in- creasing age and elevated BP. No previous studies have dis- sected the separate effects of age and BP on the diameter of retinal vessels. METHODS. This was a population-based, cross-sectional study comprising

Shweta Kaushik; Annette Kifley; Paul Mitchell; Jie Jin Wang

69

Validation of the performance of a practical blood vessel imaging system to facilitate vessel punctures  

NASA Astrophysics Data System (ADS)

A practical system to visualize vessels underneath the skin has been developed, based on near-infrared (NIR) transillumination. A study in the clinical setting proved the system to be useful as a support in blood withdrawal in young children. During clinical application it was found that performance varied depending on vessel size, depth of vessels and surrounding lighting conditions. To gain more insight on the different variables that determine functioning of the system, we performed phantom studies. A combined liquid/solid phantom was fabricated with similar optical properties as the tissue layers of skin reported in literature at 850 nm. This phantom was used to estimate the depth of visibility in the relation to vessel size and darkness of the skin. Vessel contrast was determined analytically from images and evaluated by 3 independent observers. The knowledge gained from these experiments will be helpful to improve the imaging system and develop a solid phantom to be used as a gold standard to test the system under various clinical lighting conditions. The working range of the system was found to be appropriate to visualize the vessels used for the most procedures, such as blood withdrawal and placement of intravenous lines.

Cuper, Natascha J.; Verdaasdonk, Rudolf M.; de Roode, Rowland

2009-02-01

70

Interest of ICG blood clearance monitoring for reproducible 810-nm diode laser coagulation of blood vessels  

NASA Astrophysics Data System (ADS)

Purpose: To evaluate a method of control of diode laser fluence leading to a reproducible ICG-enhanced selective photocoagulation of blood vessels. This method would use the chromophore clearance, i.e. ICG blood concentration decay to adapt the laser fluence. Materials and Methods: A skin flap window was used on hamsters. After a 15 mg/kg ICG solution injection, photocoagulation of vessels were performed. Results: Selective photocoagulation of blood vessels was obtained only during the first 10 minutes. The fluence required to obtain a selective photocoagulation of vessels (F) was modelized using a one compartment phamacokinetic equation: F equals Of(1-e-t/(tau )). The best fit was obtained for a time constant (tau) equals 4.8 min and Of equals 300 J/cm2 (correlation coefficient r2 equals 0.996). During the first 10 minutes, the fluence required for selective photocoagulation of vessels was increased by a factor 4.5. Conclusion: Fluence required for a selective photocoagulation of vessels was correlated to ICG blood concentration decay. The time constant was equivalent to ICG half-life time in human blood. These results demonstrate that diode laser ICG-enhanced photocoagulation can be controlled by monitoring the ICG blood clearance.

Desmettre, Thomas; Soulie-Begu, Sylvie; Devoisselle, Jean-Marie; Mordon, Serge R.

1999-02-01

71

Gross anatomy of the cardiac blood vessels in the North American beaver (Castor canadensis).  

PubMed

The cardiac arteries and veins are described in the North American beaver (Castor canadensis) following the injection of the vessels of 15 hearts with either latex, vinyl plastic or barium sulfate. The left coronary artery gives off the typical circumflex and paraconal interventricular branches which supply the left atrium and ventricle and part of the right ventricle and interventricular septum. The right coronary artery vascularizes the right atrium and ventricule and by means of its subsinuosal interventricular branch, part of the left ventricle and interventricular septum. The paraconal interventricular branch of the left coronary artery lies within the myocardium and is not visible on the surface of the heart. There are no intercoronary anastomoses between the right and left vessels. The major cardiac veins open into the terminal end of the left cranial vena cava. Unlike the arteries, there are venous anastomoses interconnecting the great cardiac vein and the middle cardiac vein. It is concluded that the cardiac blood vessels in Castor canadensis are typically mammalian and resemble those of both land and aquatic mammals. PMID:7305001

Bisaillon, A

1981-01-01

72

Multiscale fabrication of a transparent circulation type blood vessel simulator  

PubMed Central

We proposed and fabricated multiscale transparent arteriole and capillary vessel models with circular cross sections of 10500 ?m using photolithography. The circularities of the fabricated 10, 50, and 500 ?m diameter microchannels were 84.0%, 61.5%, and 82.3%, respectively. Next, we connected these different models to realize a circulation type blood vessel model simulating arteriole networks. We proposed a novel connection method using an intermediate connector made of wax, which we used to connect these models to make a circulation model. In flow experiments, the fabricated models showed no leakage and circulation models with seamless connections were achieved. PMID:21264060

Nakano, Takuma; Itoyama, Taro; Yoshida, Keisuke; Sawada, Yu; Ikeda, Seiichi; Fukuda, Toshio; Matsuda, Takehisa; Negoro, Makoto; Arai, Fumihito

2010-01-01

73

Study Ties Shingles Virus to Dangerous Blood Vessel Disease in Elderly  

MedlinePLUS

... this page, please enable JavaScript. Study Ties Shingles Virus to Dangerous Blood Vessel Disease in Elderly Condition ... 18, 2015 (HealthDay News) -- New research links the virus behind chickenpox and shingles to a blood vessel ...

74

Investigating pulsed dye laser-blood vessel interaction with color Doppler optical coherence  

E-print Network

Investigating pulsed dye laser-blood vessel interaction with color Doppler optical coherence irradiated blood vessels has been achieved using Color Doppler Optical Coherence Tomography (CDOCT was used to irradiate hamster dorsal skin flap window preparations. Irradiation sites were imaged

Barton, Jennifer K.

75

Control of Blood Vessel Identity: From Embryo to Adult  

PubMed Central

Arteries and veins have been historically defined by the direction of blood flow and oxygen tension within the vessel, in addition to their functional, hemodynamic, and anatomical differences. It is now known that the molecular identity of these vessels is genetically predetermined, with specific molecular pathways activated during the development of arteries and veins. Eph-B4 is a determinant of venous differentiation and Ephrin-B2 is a determinant of arterial differentiation. Placement of a vein into the higher pressure and flow of the arterial circulation results in adaptation of the vein to the arterial environment. There is selective loss of Eph-B4 expression without induction of Ephrin-B2 expression during vein graft adaptation. These findings suggest that loss of venous identity is the crucial mechanism in vein graft adaptation and that developmentally critical determinants of vessel identity are plastic during adult life. PMID:23555335

2008-01-01

76

Regulation of blood vessels by prolactin and vasoinhibins.  

PubMed

Prolactin (PRL) stimulates the growth of new blood vessels (angiogenesis) either directly through actions on endothelial cells or indirectly by upregulating proangiogenic factors like vascular endothelial growth factor (VEGF). Moreover, PRL acquires antiangiogenic properties after undergoing proteolytic cleavage to vasoinhibins, a family of PRL fragments (including 16kDa PRL) with potent antiangiogenic, vasoconstrictive, and antivasopermeability effects. In view of the opposing actions of PRL and vasoinhibins, the regulation of the proteases responsible for specific PRL cleavage represents an efficient mechanism for controlling blood vessel growth and function. This review briefly describes the vascular actions of PRL and vasoinhibins, and addresses how their interplay could help drive biological effects of PRL in the context of health and disease. PMID:25472535

Clapp, Carmen; Thebault, Stphanie; Macotela, Yazmn; Moreno-Carranza, Bibiana; Triebel, Jakob; Martnez de la Escalera, Gonzalo

2015-01-01

77

Investigation on artificial blood vessels prepared from bacterial cellulose.  

PubMed

BC (bacterial cellulose) exhibits quite distinctive properties than plant cellulose. The outstanding properties make BC a promising material for preparation of artificial blood vessel. By taking advantage of the high oxygen permeability of PDMS (polydimethylsiloxane) as a tubular template material, a series of BC tubes with a length of 100 mm, a thickness of 1mm and an outer diameter of 4 or 6mm were biosynthesized with the help of Gluconacetobacter xylinum. Through characterization by SEM (scanning electron microscope), tensile testing and thermal analysis, it is demonstrated that BC tubes are good enough for artificial blood vessel with elaborated nano-fiber architecture, qualified mechanical properties and high thermal stability. In addition, measurement of biocompatibility also shows that BC tubes are greatly adaptable to the in vivo environment. The results indicate that BC tubes have great potential for being utilized as tubular scaffold materials in the field of tissue engineering. PMID:25491966

Zang, Shanshan; Zhang, Ran; Chen, Hua; Lu, Yudong; Zhou, Jianhai; Chang, Xiao; Qiu, Guixing; Wu, Zhihong; Yang, Guang

2015-01-01

78

Heterogeneity of angiogenesis and blood vessel maturation in cartilage tumors.  

PubMed

Cartilage tumors have a special angiogenic phenotype, with blood vessels arranged predominantly in pericartilage fibrous septa and relatively low microvessel density (MVD), except in dedifferentiated chondrosarcomas. To further elucidate angiogenesis in cartilage tumors, we used double-labeling immunohistochemistry to determine microvessel pericyte coverage index (MPI) and proliferating capillary index (PCI), referring to blood vessel maturation and angiogenic activity in enchondromas, conventional chondrosarcomas, and dedifferentiated chondrosarcomas. Altogether, we found high MPIs (>70%) especially in dedifferentiated chondrosarcomas but without a correlation to the grade of malignancy. PCI was significantly higher in conventional chondrosarcomas grades II and III than in enchondromas, chondrosarcomas grade I, and dedifferentiated chondrosarcomas. Thus, PCI positively correlated with the previously reported differential expression of vascular endothelial growth factor (VEGF)-A in cartilage tumors. Altogether, cartilage tumors exhibit a heterogeneous but predominantly mature angiogenic phenotype with differential proliferative activity. PMID:19157720

Kalinski, Thomas; Sel, Saadettin; Kouznetsova, Irina; Rpke, Martin; Roessner, Albert

2009-01-01

79

Blood vessel tracking technique for optic nerve localisation for field 1-3 color fundus images  

Microsoft Academic Search

This paper considers the problem of locating the optic nerve center, a place where the blood vessel and nerve emanate. Our algorithm first identifies the main blood vessel, which is characterized by large width and dark red color, by using amplitude modified second-order Gaussian filter. The optic nerve center is then found by tracking along this main blood vessel to

Hwee Keong Lam; Opas Chutatape

2003-01-01

80

The tissue engineering of blood vessels and the heart.  

PubMed

The engineering of biological substitutes and strategies for the replacement and/or repair of blood vessels and the components of the heart represents an important challenge for tissue engineering. In this review, the progress to date and the barriers remaining are addressed. Even though the progress has been considerable and there are even some approaches that have entered clinical trials, we are still a ways off from having FDA-approved replacements and/or repair strategies. PMID:14871272

Nerem, Robert M; Ensley, Ann E

2004-01-01

81

Retinal Blood Vessel Test in Young-Onset Diabetic Patients  

Microsoft Academic Search

136 patients with insulin-dependent diabetes mellitus (IDDM) were shown the entoptic blood vessel figure. All patients were examined independently by retinal fluorescein angiography and ophthalmoscopy. 34 patients had no retinopathy, none of them believed to see alterations. 102 patients had different phases of diabetic retinopathy. If there were 15 microaneurysms within the 15 meridian surrounding the central fovea, 55% of

Guido Kluxen; Elke Wilden

1987-01-01

82

By Different Cellular Mechanisms, Lymphatic Vessels Sprout by Endothelial Cell Recruitment Whereas Blood Vessels Grow by Vascular Expansion  

NASA Technical Reports Server (NTRS)

The development of effective vascular therapies requires the understanding of all modes of vessel formation contributing to vasculogenesis, angiogenesis (here termed hemangiogenesis) and lymphangiogenesis. We show that lymphangiogenesis proceeds by blind-ended vessel sprouting via recruitment of isolated endothelial progenitor cells to the tips of growing vessels, whereas hemangiogenesis occurs by non-sprouting vessel expansion from the capillary network, during middevelopment in the quail chorioallantoic membrane (CAM). Blood vessels expanded out of capillaries that displayed transient expression of alpha smooth muscle actin (alphaSMA), accompanied by mural recruitment of migratory progenitor cells expressing SMA. Lymphatics and blood vessels were identified by confocal/fluorescence microscopy of vascular endothelial growth factor (VEGF) receptors VEGFR-1 and VEGFR-2, alphaSMA (expressed on CAM blood vessels but not on lymphatics), homeobox transcription factor Prox-1 (specific to CAM lymphatic endothelium), and the quail hematopoetic/vascular marker, QH-1. Expression of VEGFR-1 was highly restricted to blood vessels (primarily capillaries). VEGFR-2 was expressed intensely in isolated hematopoietic cells, lymphatic vessels and moderately in blood vessels. Prox-1 was absent from endothelial progenitor cells prior to lymphatic recruitment. Although vascular endothelial growth factor-165 (VEGF(sub 165)) is a key regulator of numerous cellular processes in hemangiogenesis and vasculogenesis, the role of VEGF(sub 165) in lymphangiogenesis is less clear. Exogenous VEGF(sub 165) increased blood vessel density without changing endogenous modes of vascular/lymphatic vessel formation or marker expression patterns. However, VEGF(sub 165) did increase the frequency of blood vascular anastomoses and strongly induced the antimaturational dissociation of lymphatics from blood vessels, with frequent formation of homogeneous lymphatic networks.

Parsons-Wingerter, Patricia; McKay, Terri L.; Leontiev, Dmitry; Condrich, Terence K.; DiCorleto, Paul E.

2005-01-01

83

Non-Newtonian flow of blood in an arteriosclerotic blood vessel with rigid permeable walls.  

PubMed

The steady, laminar and fully developed flow of blood in an arteriosclerotic blood vessel with rigid permeable walls is investigated, taking into account the slip condition at the vessel walls. The constitutive equation of blood is represented by a Casson fluid model. The model is used to study the influence of the yield stress on blood flow through arteriosclerotic arteries. The variation of the flow resistance and wall shear stress, with permeability parameter, slip parameter and Casson number are obtained for different sizes of growth of the arteriosclerotic lesions. Comparison of the results is made with available results that consider the impervious wall and those that consider blood as a Newtonian fluid. It is found that permeability has a significant effect on the values of flow resistance and wall shear stress. Biological implications of the present model on different arterial diseases are discussed. PMID:7564389

Das, B; Batra, R L

1995-07-01

84

Effect of blood vessel diameter on relative blood flow estimate in Doppler optical coherence tomography algorithms  

NASA Astrophysics Data System (ADS)

In vivo measurement of blood flow in the retina has been made possible with the advent of Fourier domain optical coherence tomography (OCT). Doppler OCT has seen many advances in recent years in algorithms used for quantifying blood flow. We compare the relative retinal blood flow estimates as measured by the standard phase-resolved (PR) algorithm and the more recent moving-scatterer-sensitive (MSS) algorithm as a function of vessel size. We find that the PR-to-MSS flow ratio significantly decreases with decreasing vessel diameter. We also develop a simulation to approximate the scattering from blood cells in tissue and compare the relative blood flow estimates. The flow ratio measured with simulation closely matches that found in vivo. Our simulation predicts that whereas PR underestimates the flow, MSS overestimates it. Our simulation may help to correct for algorithm bias in in vivo retinal flow estimates.

Tokayer, Jason; Huang, David

2011-03-01

85

Regional blood flow analysis and its relationship with arterial branch lengths and lumen volume in the coronary arterial tree  

NASA Astrophysics Data System (ADS)

The limitations of visually assessing coronary artery disease are well known. These limitations are particularly important in intermediate coronary lesions (30-70% diameter stenosis) where it is difficult to determine whether a particular lesion is the cause of ischaemia. Therefore, a functional measure of stenosis severity is needed. The purpose of this study is to determine whether the expected maximum coronary blood flow in an arterial tree is predictable from its sum of arterial branch lengths or lumen volume. Using a computer model of a porcine coronary artery tree, an analysis of blood flow distribution was conducted through a network of millions of vessels that included the entire coronary artery tree down to the first capillary branch. The flow simulation results show that there is a linear relationship between coronary blood flow and the sum of its arterial branch lengths. This relationship holds over the entire arterial tree. The flow simulation results also indicate that there is a \\frac34 power relation between coronary blood flow (Q) and the sum of its arterial lumen volume (V). Moreover, there is a linear relationship between normalized Q and normalized V raised to a power of \\frac34 over the entire arterial tree. These results indicate that measured arterial branch lengths or lumen volumes can be used to predict the expected maximum blood flow in an arterial tree. This theoretical maximum blood flow, in conjunction with an angiographically measured blood flow, can potentially be used to calculate fractional flow reserve based entirely on angiographic data.

Molloi, Sabee; Wong, Jerry T.

2007-03-01

86

Non-respiratory blood vessels in Latimeria gill filaments  

PubMed Central

A study of the blood pathways within the gills of Latimeria has been carried out using light and transmission electron microscopy. Clear evidence has been found for the presence of a secondary non-respiratory circulation in addition to the well-established respiratory pathway through the gill lamellae. All essential components of this system have been observed and have the same relationships and basic structure as comparable secondary systems in actinopterygian and elasmobranch fishes. These include a central venous sinus (CVS), arterio-venous anastomoses (AVAs) and central filament arteries (CFAs). AVAs connect both arterial vessels of the primary circulation and CFAs of the secondary circulation to the CVS. The latter contained many red blood cells. The presence of this secondary circulation in Latimeria gills contrasts with the situation in the gills of the three living genera of lungfishes where a system possessing the essential features of the tetrapod lymphatic vessel system has been recognized. No suggestions of a true lymphatic vessel system were observed in Latimeria. Other features of gill and vascular anatomy in Latimeria show its closer relationship to dipnoans than other groups of living fishes but evidence derived from this study of the secondary circulation clearly supports the view that the Dipnoi rather than Latimeria represent the living fishes most closely related to the tetrapods.

Vogel, W. O. P.

1998-01-01

87

Blood vessel classification into arteries and veins in retinal images  

NASA Astrophysics Data System (ADS)

The prevalence of diabetes is expected to increase dramatically in coming years; already today it accounts for a major proportion of the health care budget in many countries. Diabetic Retinopathy (DR), a micro vascular complication very often seen in diabetes patients, is the most common cause of visual loss in working age population of developed countries today. Since the possibility of slowing or even stopping the progress of this disease depends on the early detection of DR, an automatic analysis of fundus images would be of great help to the ophthalmologist due to the small size of the symptoms and the large number of patients. An important symptom for DR are abnormally wide veins leading to an unusually low ratio of the average diameter of arteries to veins (AVR). There are also other diseases like high blood pressure or diseases of the pancreas with one symptom being an abnormal AVR value. To determine it, a classification of vessels as arteries or veins is indispensable. As to our knowledge despite the importance there have only been two approaches to vessel classification yet. Therefore we propose an improved method. We compare two feature extraction methods and two classification methods based on support vector machines and neural networks. Given a hand-segmentation of vessels our approach achieves 95.32% correctly classified vessel pixels. This value decreases by 10% on average, if the result of a segmentation algorithm is used as basis for the classification.

Kondermann, Claudia; Kondermann, Daniel; Yan, Michelle

2007-03-01

88

Blood vessel repair and regeneration in the ischaemic heart  

PubMed Central

The term therapeutic angiogenesis originated almost two decades ago, following evidence that factors that promote blood vessel formation could be delivered to ischaemic tissues and restore blood flow. Following this proof-of-principle, safety and efficacy of the best-studied angiogenic factors (eg, vascular endothelial growth factor) were demonstrated in early clinical studies. Promising results led to the development of larger controlled trials that, unfortunately, have failed to satisfy the initial expectations of therapeutic angiogenesis for ischaemic heart disease. As the quest to delay the progression to heart failure secondary to ischaemic heart disease continues, alternative therapies have emerged as potential novel treatments to improve myocardial reperfusion and long-term heart function. The disappointing results of the clinical studies using angiogenic factors were followed by mixed results from the cell therapy trials. This review reflects the current angiogenic strategies for the ischaemic heart, their limitations and discusses future perspectives in the light of recent scientific and clinical evidence. It is proposed that combination therapies may be a new direction to advance therapeutic repair and regeneration of blood vessels in the ischaemic heart. PMID:25332783

Zhang, Huajun; van Olden, Casper; Sweeney, Dominic; Martin-Rendon, Enca

2014-01-01

89

Effect of non-Newtonian characteristics of blood on magnetic particle capture in occluded blood vessel  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles drug carriers continue to attract considerable interest for drug targeting in the treatment of cancer and other pathological conditions. Magnetic carrier particles with surface-bound drug molecules are injected into the vascular system upstream from the desired target site, and are captured at the target site via a local applied magnetic field. Herein, a numerical investigation of steady magnetic drug targeting (MDT) using functionalized magnetic micro-spheres in partly occluded blood vessel having a 90 bent is presented considering the effects of non-Newtonian characteristics of blood. An Eulerian-Lagrangian technique is adopted to resolve the hemodynamic flow and the motion of the magnetic particles in the flow using ANSYS FLUENT. An implantable infinitely long cylindrical current carrying conductor is used to create the requisite magnetic field. Targeted transport of the magnetic particles in a partly occluded vessel differs distinctly from the same in a regular unblocked vessel. Parametric investigation is conducted and the influence of the insert configuration and its position from the central plane of the artery (zoffset), particle size (dp) and its magnetic property (?) and the magnitude of current (I) on the "capture efficiency" (CE) is reported. Analysis shows that there exists an optimum regime of operating parameters for which deposition of the drug carrying magnetic particles in a target zone on the partly occluded vessel wall can be maximized. The results provide useful design bases for in vitro set up for the investigation of MDT in stenosed blood vessels.

Bose, Sayan; Banerjee, Moloy

2015-01-01

90

Homocysteine induces blood vessel global hypomethylation mediated by LOX-1.  

PubMed

Homocysteine (Hcy) is an independent risk factor of atherosclerosis through its involvement with the methionine cycle. In this study, we aimed to determine the blood vessel global methylation rate in Hcy-induced atherosclerosis in apolipoprotein-E-deficient (ApoE-/-) mice, and to explore the possible mechanism of this change in endothelial cells. ApoE-/- mice were divided into a hyperlipidemia (HLP) group, a hyperhomocysteinemia (HHcy) group, and an HHcy + folate + vitamin B12 (HHcy+FA+VB) group. Wild-type C57BL/6J mice were prepared as controls. Total Hcy, lipids, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) contents in serum were measured with an automatic biochemistry analyzer and high-performance liquid chromatography. Methylation of B1 repetitive elements in blood vessels was tested using nested methylation-specific-polymerase chain reaction (nMS-PCR). Endothelial cells (ECs) were pretreated with Hcy or by adding FA and VB. Lectin-like oxidized LDL receptor-1 (LOX-1) expressions were determined by quantitative PCR, Western blot, and nMS-PCR. The HHcy group displayed severe HLP and HHcy. SAM and SAH contents were also elevated in the HHcy group compared with other groups. Methylation of B1 repetitive elements was significantly increased in the HHcy group (0.5050 0.0182) compared to the HLP (0.5158 0.0163) and control (0.5589 0.0236) groups. mRNA and protein expressions of LOX-1 increased (0.2877 0.0341, 0.6090 0.0547), whereas methylation expression decreased (0.5527 0.0148) after 100 ?M Hcy stimulation in ECs. In conclusion, Hcy-induced atherosclerosis was closely associated with induced hypomethylation status in the blood vessel, and this process was partially mediated by LOX-1 DNA methylation. PMID:24938465

Yang, X L; Tian, J; Liang, Y; Ma, C J; Yang, A N; Wang, J; Ma, S C; Cheng, Y; Hua, X; Jiang, Y D

2014-01-01

91

Triamcinolone Acetonide Selectively Inhibits Angiogenesis in Small Blood Vessels and Decreases Vessel Diameter within the Vascular Tree  

NASA Technical Reports Server (NTRS)

The steroid triamcinolone acetonide (TA) is a potent anti-angiogenesis drug used to treat retinal vascular diseases that include diabetic retinopathy, vascular occlusions and choroidal neovascularization. To quantify the effects of TA on branching morphology within the angiogenic microvascular tree of the chorioallantoic membrane (CAM) of quail embryos. Increasing concentrations of TA (0-16 ng/ml) were applied topically on embryonic day 7 (E7) to the chorioallantoic membrane (CAM) of quail embryos cultured in Petri dishes, and incubated for an additional 24 or 48 hours until fixation. Binary (black/white) microscopic images of arterial end points were quantified by VESGEN software (for Generational Analysis of Vessel Branching) to obtain major vascular parameters that include vessel diameter (Dv), fractal dimension (Df), tortuosity (Tv) and densities of vessel area, length, number and branch point (Av, Lv, Nv and Brv). For assessment of specific changes in vascular morphology induced by TA, the VESGEN software automatically segmented the vascular tree into branching generations (G1...G10) according to changes in vessel diameter and branching. Vessel density decreased significantly up to 34% as the function of increasing concentration of TA according to Av, Lv, Brv, Nv and Df. TA selectively inhibited the growth of new, small vessels, because Lv decreased from 13.14plus or minus 0.61 cm/cm2 for controls to 8.012 plus or minus 0.82 cm/cm2 at 16 ng TA/ml in smaller branching generations (G7-G10), and for Nv from 473.83 plus or minus 29.85 cm(-)2 to 302.32 plus or minus 33.09 cm-()2. In contrast, vessel diameter (Dv) decreased throughout the vascular tree (G1-G10).

McKay, Terri L.; Gredeon, Dan J.; Vickerman, Mary B.; Hylton, alan G.; Ribita, Daniela; Olar, Harry H.; Kaiser, Peter K.; Parsons-Wingerter, Patricia

2007-01-01

92

Microfluidic strategy to investigate dynamics of small blood vessel function  

NASA Astrophysics Data System (ADS)

Resistance arteries (RAs, 30-300 microns in diameter) that are located within the terminal part of the vascular tree regulate the laminar perfusion of tissue with blood, via the peripheral vascular resistance, and hence controls the systemic blood pressure. The structure of RAs is adapted to actively controlling flow resistance by dynamically changing their diameter, which is non-linearly dependent on the temporal variation of the transmural pressure, perfusion flow rate and spatiotemporal changes in the chemical environment. Increases in systemic blood pressure (hypertension) resulting from pathologic changes in the RA response represent the primary risk factor for cardiovascular diseases. We use a microfluidic strategy to investigate small blood vessels by quantifying structural variations within the arterial wall, RA outer contour and diameter over time. First, we document the artery response to vasomotor drugs that were homogeneously applied at step-wise increasing concentration. Second, we investigate the response in the presence of well-defined axial and circumferential heterogeneities. Artery per- and superfusion is discussed based on microscale PIV measurements of the fluid velocity on both sides of the arterial wall. Structural changes in the arterial wall are quantified using cross-correlation and proper orthogonal decomposition analyses of bright-field micrographs.

Yasotharan, Sanjesh; Bolz, Steffen-Sebastian; Guenther, Axel

2010-11-01

93

Effect of soluble epoxide hydrolase inhibition on epoxyeicosatrienoic acid metabolism in human blood vessels  

E-print Network

blood vessels Xiang Fang,1 Neal L. Weintraub,2,3,4 Ryan B. McCaw,1 Shanming Hu,1 Shawn D. Harmon,1 James on epoxyeicosatrienoic acid metabolism in human blood vessels. Am J Physiol Heart Circ Physiol 287: H2412­H2420, 2004 epoxide hydrolase (sEH) inhibition on epoxyei- cosatrienoic acid (EET) metabolism in intact human blood

Hammock, Bruce D.

94

Bioprinting of artificial blood vessels: current approaches towards a demanding goal.  

PubMed

Free-form fabrication techniques, often referred to as '3D printing', are currently tested with regard to the processing of biological and biocompatible materials in general and for fabrication of vessel-like structures in particular. Such computer-controlled methods assemble 3D objects by layer-wise deposition or layer-wise cross-linking of materials. They use, for example, nozzle-based deposition of hydrogels and cells, drop-on-demand inkjet-printing of cell suspensions with subsequent cross-linking, layer-by-layer cross-linking of synthetic or biological polymers by selective irradiation with light and even laser-induced deposition of single cells. The need of vessel-like structures has become increasingly crucial for the supply of encapsulated cells for 3D tissue engineering, or even with regard to future application such as vascular grafts. The anticipated potential of providing tubes with tailored branching geometries made of biocompatible or biological materials pushes future visions of patient-specific vascularized tissue substitutions, tissue-engineered blood vessels and bio-based vascular grafts. We review here the early attempts of bringing together innovative free-form manufacturing processes with bio-based and biodegradable materials. The presented studies provide many important proofs of concepts such as the possibility to integrate viable cells into computer-controlled processes and the feasibility of supplying cells in a hydrogel matrix by generation of a network of perfused channels. Several impressive results in the generation of complex shapes and high-aspect-ratio tubular structures demonstrate the potential of additive assembly methods. Yet, it also becomes obvious that there remain major challenges to simultaneously match all material requirements in terms of biological functions (cell function supporting properties), physicochemical functions (mechanical properties of the printed material) and process-related (viscosity, cross-linkability) functions, towards the demanding goal of biofabricating artificial blood vessels. PMID:24970571

Hoch, Eva; Tovar, Gnter E M; Borchers, Kirsten

2014-11-01

95

Development of blood vessel searching system using near-infrared light stereo method for clinical blood sampling  

NASA Astrophysics Data System (ADS)

We developed an accurate three-dimensional blood vessel search (3D BVS) system using NIR light for the clinical blood sampling. In the previous study, the 3D BVS system, which used near-infrared (NIR) light imaging and the stereo method to locate blood vessel accurately in three dimensions has been developed(1). However, as NIR lights could not transmit the human arm, this system could not be used for the subcutaneous blood vessel detection. In this study, we developed a BVS by using the reflecting NIR light for blood sampling assist. The light scattering in human tissue will cause blur of blood vessel edge in image, that makes the diameter of blood vessel became uncertain. In this study, a light propagation simulation and a multilayer phantom were adopted to estimate the measurement error of blood vessel diameter in our BSV system. In the simulation, the optical properties of scattering coefficient, absorption coefficient, and refractive index were set similar with human skin. Next, we fabricated a multilayer phantom, which has the similar structure and optical properties with the human skin to confirm availability of the simulation. Also, the optical properties of our phantom are adjustable in our phantom to imitate the different color of skin. We established the estimation algorithm to detect the blood vessel accurately. Finally, we confirm the availability of our BVS for the blood sampling assist system.

Cheng, Kai; Morita, Yusuke; Nakamachi, Eiji; Honda, Norihiro; Awazu, Kunio

2014-10-01

96

Lama1 mutations lead to vitreoretinal blood vessel formation, persistence of fetal vasculature, and epiretinal membrane formation in mice  

PubMed Central

Background Valuable insights into the complex process of retinal vascular development can be gained using models with abnormal retinal vasculature. Two such models are the recently described mouse lines with mutations in Lama1, an important component of the retinal internal limiting membrane (ILM). These mutants have a persistence of the fetal vasculature of vitreous (FVV) but lack a primary retinal vascular plexus. The present study provides a detailed analysis of astrocyte and vascular development in these Lama1 mutants. Results Although astrocytes and blood vessels initially migrate into Lama1 mutant retinas, both traverse the peripapillary ILM into the vitreous by P3. Once in the vitreous, blood vessels anastomose with vessels of the vasa hyaloidea propria, part of the FVV, and eventually re-enter the retina where they dive to form the inner and outer retinal capillary networks. Astrocytes continue proliferating within the vitreous to form a dense mesh that resembles epiretinal membranes associated with persistent fetal vasculature and proliferative vitreoretinopathy. Conclusions Lama1 and a fully intact ILM are required for normal retinal vascular development. Mutations in Lama1 allow developing retinal vessels to enter the vitreous where they anastomose with vessels of the hyaloid system which persist and expand. Together, these vessels branch into the retina to form fairly normal inner retinal vascular capillary plexi. The Lama1 mutants described in this report are potential models for studying the human conditions persistent fetal vasculature and proliferative vitreoretinopathy. PMID:21999428

2011-01-01

97

Enhanced absorption of millimeter wave energy in murine subcutaneous blood vessels.  

PubMed

The aim of the present study was to determine millimeter wave (MMW) absorption by blood vessels traversing the subcutaneous fat layer of murine skin. Most calculations were performed using the finite-difference time-domain (FDTD) technique. We used two types of models: (1) a rectangular block of multilayer tissue with blood vessels traversing the fat layer and (2) cylindrical models with circular and elliptical cross-sections simulating the real geometry of murine limbs. We found that the specific absorption rate (SAR) in blood vessels normally traversing the fat layer achieved its maximal value at the parallel orientation of the E-field to the vessel axis. At 42 GHz exposure, the maximal SAR in small blood vessels could be more than 30 times greater than that in the skin. The SAR increased with decreasing the blood vessel diameter and increasing the fat thickness. The SAR decreased with increasing the exposure frequency. When the cylindrical or elliptical models of murine limbs were exposed to plane MMW, the greatest absorption of MMW energy occurred in blood vessels located on the lateral areas of the limb model. At these areas the maximal SAR values were comparable with or were greater than the maximal SAR on the front surface of the skin. Enhanced absorption of MMW energy by blood vessels traversing the fat layer may play a primary role in initiating MMW effects on blood cells and vasodilatation of cutaneous blood vessels. PMID:21344460

Alekseev, Stanislav I; Ziskin, Marvin C

2011-09-01

98

ENHANCED ABSORPTION OF MILLIMETER WAVE ENERGY IN MURINE SUBCUTANEOUS BLOOD VESSELS  

PubMed Central

The aim of the present study was to determine millimeter wave (MMW) absorption by blood vessels traversing the subcutaneous fat layer of murine skin. Most calculations were performed using the finite-difference time-domain (FDTD) technique. We used two types of models: (1) a rectangular block of multilayer tissue with blood vessels traversing the fat layer and (2) cylindrical models with circular and elliptical cross sections simulating the real geometry of murine limbs. We found that the specific absorption rate (SAR) in blood vessels normally traversing the fat layer achieved its maximal value at the parallel orientation of the E-field to the vessel axis. At 42 GHz exposure, the maximal SAR in small blood vessels could be more than 30 times greater than that in the skin. The SAR increased with decreasing the blood vessel diameter and increasing the fat thickness. The SAR decreased with increasing the exposure frequency. When the cylindrical or elliptical models of murine limbs were exposed to plane MMW, the greatest absorption of MMW energy occurred in blood vessels located on the lateral areas of the limb model. At these areas the maximal SAR values were comparable with or were greater than the maximal SAR on the front surface of the skin. Enhanced absorption of MMW energy by blood vessels traversing the fat layer may play a primary role in initiating MMW effects on blood cells and vasodilatation of cutaneous blood vessels. PMID:21344460

Alekseev, Stanislav I.; Ziskin, Marvin C.

2011-01-01

99

Red blood cells augment leukocyte rolling in a virtual blood vessel.  

PubMed Central

Leukocyte rolling and arrest on the vascular endothelium is a central event in normal and pathological immune responses. However, rigorous estimation of the fluid and surface forces involved in leukocyte-endothelial interactions has been difficult due to the particulate, non-Newtonian nature of blood. Here we present a Lattice-Boltzmann approach to quantify forces exerted on rolling leukocytes by red blood cells in a "virtual blood vessel." We report that the normal force imparted by erythrocytes is sufficient to increase leukocyte binding and that increases in tangential force and torque can promote rolling of previously adherent leukocytes. By simulating changes in hematocrit we show that a close "envelopment" of the leukocyte by the red blood cells is necessary to produce significant changes in the forces. This novel approach can be applied to a large number of biological and industrial problems involving the complex flow of particulate suspensions. PMID:12324405

Migliorini, Cristiano; Qian, YueHong; Chen, Hudong; Brown, Edward B; Jain, Rakesh K; Munn, Lance L

2002-01-01

100

Illustration of the heart and blood vessels in medieval times.  

PubMed

Throughout history, illustrations had played a key role in the promotion and evolution of medicine by providing a medium for transmission of scientific observations. Due to religious prohibitions, color drawings of the human body did not appear in medieval Persia and during the Islamic Golden Age. This tradition, however, has been overlooked with the publication of the first color atlas and text of human anatomy, Tashrihi Mansuri (Mansur's Anatomy), by Mansur ibn Ilyas in the fourteenth century AD. Written in Persian and containing several vivid illustrations of the human body, this book gained widespread attention by both scholars and lay persons. In this article, a brief history of Mansur's Anatomy and an English translation of selected sections from this book regarding the heart and blood vessels are presented. PMID:20060606

Khalili, Majid; Shoja, Mohammadali M; Tubbs, R Shane; Loukas, Marios; Alakbarli, Farid; Newman, Andrew J

2010-08-01

101

Translating the Conversation Between the Brain and Blood Vessels  

NSDL National Science Digital Library

?We?re studying why people who are obese become hypertensive,? Dr. Schreihofer said of one aspect of her work. ?We believe this is due to something about the obese state: We don?t know what that is, but we?re starting to rule things out.? Indeed, the Schreihofer laboratory has already answered one question: Does hypertension occur because the brain loses its ability to sense that the blood vessels are stretching under high pressure? In a study with obese rats, they found the rats? brains could sense the stretch but still became hypertensive, eliminating that mechanism as a possibility.

APS Communications Office (American Physiological Society Communications Office)

2006-04-21

102

Electromagnetic drive of microrobot geometrically constrained in blood vessel.  

PubMed

We propose new electromagnetic actuation of a microrobot by utilizing geometric constraints in a blood vessel. In our concept, a microrobot travels in a vascular network while keeping the contact to the vascular wall. In the paper, forces working on the microrobot are modeled in two dimensions, and conditions to propel the microrobot while pushing it against the vascular wall are described. The design of the microrobot composed of three permanent magnets is also presented. The feasibility of the 2D actuation of the microrobot was confirmed using an experimental setup composed of four pairs of coils generating both uniform magnetic fields and uniform magnetic field gradients. Finally, the model was extended to 3D in order to investigate 3D actuation of the microrobot. PMID:22255867

Nakamura, S; Harada, K; Sugita, N; Mitsuishi, M; Kaneko, M

2011-01-01

103

Heterogeneity of muscarinic receptor subtypes in cerebral blood vessels  

SciTech Connect

The identity and distribution of muscarinic cholinergic receptor subtypes and associated signal transduction mechanisms was characterized for the cerebral circulation using correlated functional and biochemical investigations. Subtypes were distinguished by the relative affinities of a panel of muscarinic antagonists, pirenzepine, AF-DX 116 (11-2-((2-(diethylaminomethyl)- 1-piperidinyl)acetyl)-5,11-dihydro-6H- pyrido(2,3-b)(1,4)benzodiazepine-6-one), hexahydrosiladifenidol, methoctramine, 4-diphenylacetoxy-N-methylpiperidine methobromide, dicyclomine, para-fluoro-hexahydrosiladifenidol and atropine. Muscarinic receptors characterized by inhibition of (3H)quinuclidinylbenzilate binding in membranes of bovine pial arteries were of the M2 subtype. In contrast pharmacological analysis of (3H)-quinuclidinylbenzilate binding in bovine intracerebral microvessels suggests the presence of an M4 subtype. Receptors mediating endothelium-dependent vasodilation in rabbit pial arteries were of the M3 subtype, whereas muscarinic receptors stimulating endothelium-independent phosphoinositide hydrolysis in bovine pial arteries were of the M1 subtype. These findings suggest that characteristics of muscarinic receptors in cerebral blood vessels vary depending on the type of vessel, cellular location and function mediated.

Garcia-Villalon, A.L.; Krause, D.N.; Ehlert, F.J.; Duckles, S.P. (Department of Pharmacology, College of Medicine, University of California, Irvine (USA))

1991-07-01

104

Normalization of tumour blood vessels improves the delivery of nanomedicines in a size-dependent manner  

E-print Network

The blood vessels of cancerous tumours are leaky and poorly organized. This can increase the interstitial fluid pressure inside tumours and reduce blood supply to them, which impairs drug delivery. Anti-angiogenic ...

Chauhan, Vikash P.

105

Blood Vessel Normalization in the Hamster Oral Cancer Model for Experimental Cancer Therapy Studies  

SciTech Connect

Normalization of tumor blood vessels improves drug and oxygen delivery to cancer cells. The aim of this study was to develop a technique to normalize blood vessels in the hamster cheek pouch model of oral cancer. Materials and Methods: Tumor-bearing hamsters were treated with thalidomide and were compared with controls. Results: Twenty eight hours after treatment with thalidomide, the blood vessels of premalignant tissue observable in vivo became narrower and less tortuous than those of controls; Evans Blue Dye extravasation in tumor was significantly reduced (indicating a reduction in aberrant tumor vascular hyperpermeability that compromises blood flow), and tumor blood vessel morphology in histological sections, labeled for Factor VIII, revealed a significant reduction in compressive forces. These findings indicated blood vessel normalization with a window of 48 h. Conclusion: The technique developed herein has rendered the hamster oral cancer model amenable to research, with the potential benefit of vascular normalization in head and neck cancer therapy.

Ana J. Molinari; Romina F. Aromando; Maria E. Itoiz; Marcela A. Garabalino; Andrea Monti Hughes; Elisa M. Heber; Emiliano C. C. Pozzi; David W. Nigg; Veronica A. Trivillin; Amanda E. Schwint

2012-07-01

106

Aquaporin-1 in blood vessels of rat circumventricular organs.  

PubMed

Although the water channel protein aquaporin-1 (AQP1) is widely observed outside the rat brain in continuous, but not fenestrated, vascular endothelia, it has not previously been observed in any endothelia within the normal rat brain and only to a limited extent in the human brain. In this immunohistochemical study of rat brain, AQP1 has also been found in microvessel endothelia, probably of the fenestrated type, in all circumventricular organs (except the subcommissural organ and the vascular organ of the lamina terminalis): in the median eminence, pineal, subfornical organ, area postrema and choroid plexus. The majority of microvessels in the median eminence, pineal and choroid plexus, known to be exclusively fenestrated, are shown to be AQP1-immunoreactive. In the subfornical organ and area postrema in which many, but not all, microvessels are fenestrated, not all microvessels are AQP1-immunoreactive. In the AQP1-immunoreactive microvessels, the AQP1 probably facilitates water movement between blood and interstitium as one component of the normal fluxes that occur in these specialised sensory and secretory areas. AQP1-immunoreactive endothelia have also been seen in a small population of blood vessels in the cerebral parenchyma outside the circumventricular organs, similar to other observations in human brain. The proposed development of AQP1 modulators to treat various brain pathologies in which AQP1 plays a deleterious role will necessitate further work to determine the effect of such modulators on the normal function of the circumventricular organs. PMID:20177708

Wilson, Alan J; Carati, Colin J; Gannon, Bren J; Haberberger, Rainer; Chataway, Tim K

2010-04-01

107

Statistical pattern analysis of blood vessel features on retina images and its application to blood vessel mapping algorithms.  

PubMed

Computer based modeling and analysis of blood vessel (BV) networks is essential for automated detection and tracking of anomalies and structural changes in retina images. Among many published techniques for automated BV mapping, optimal selection of thresholds to delineate BV pixels from their background pixels remains an open problem. In this paper we propose a novel representation of a BV pixel feature, daisy graph, using rotational contrast transform (RCT), and two feature descriptors energy E(p) and symmetry difference S(p) of the daisy graph. Non-BV pixels are separated from BV and boundary pixels based on E(p). Fitness of the lognormal distribution to S(p) of BV pixels with negative E(p) has been tested extensively for images in the STARE and DRIVE databases. Based on statistical pattern analysis in the feature space, we propose a fast self-calibrated BV mapping algorithm which achieve comparable and statistically sound performance as contemporary solutions. PMID:25571441

Ying, Huajun; Wang, Xing; Liu, Jyh-Charn

2014-01-01

108

Numerical investigation of blood flow in a deformable coronary bifurcation and non-planar branch  

PubMed Central

Introduction: Among cardiovascular diseases, arterials stenosis is recognized more commonly than the others. Hemodynamic characteristics of blood play a key role in the incidence of stenosis. This paper numerically investigates the pulsatile blood flow in a coronary bifurcation with a non-planar branch. To create a more realistic analysis, the wall is assumed to be compliant. Furthermore, the flow is considered to be three-dimensional, incompressible, and laminar. Methods: The effects of non-Newtonian blood, compliant walls and different angles of bifurcation on hemodynamic characteristics of flow were evaluated. Shear thinning of blood was simulated with the Carreau-Yasuda model. The current research was mainly focused on the flow characteristics in bifurcations since atherosclerosis occurs mostly in bifurcations. Moreover, as the areas with low shear stresses are prone to stenosis, these areas were identified. Results: Our findings indicated that the compliant model of the wall, bifurcations angle, and other physical properties of flow have an impact on hemodynamics of blood flow. Lower wall shear stress was observed in the compliant wall than that in the rigid wall. The outer wall of bifurcation in all models had lower wall shear stress. In bifurcations with larger angles, wall shear stress was higher in outer walls, and lower in inner walls. Conclusion: The non-Newtonian blood vessels and different angles of bifurcation on hemodynamic characteristics of flow evaluation confirmed a lower wall shear stress in the compliant wall than that in the rigid wall, while the wall shear stress was higher in outer walls but lower in inner walls in the bifurcation regions with larger angles. PMID:25671176

Razavi, Seyed Esmail; Omidi, Amir Ali; Saghafi Zanjani, Massoud

2014-01-01

109

Ergot Alkaloid-Induced Blood Vessel Dysfunction Contributes to Fescue Toxicosis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Many effects of fescue toxicosis in grazing animals may be explained by compromised blood vessel function which is linked to the presence of ergot alkaloids in endophyte-infected tall fescue. The bodys network of blood vessels provides for the removal of metabolic waste products and delivery of the...

110

Detection of blood vessels in retinal images using two-dimensional matched filters  

Microsoft Academic Search

Blood vessels usually have poor local contrast, and the application of existing edge detection algorithms yield results which are not satisfactory. An operator for feature extraction based on the optical and spatial properties of objects to be recognized is introduced. The gray-level profile of the cross section of a blood vessel is approximated by a Gaussian-shaped curve. The concept of

SUBHASIS CHAUDHURI; SHANKAR CHATTERJEE; NORMAN KATZ; MARK NELSON; MICHAEL GOLDBAUM

1989-01-01

111

Extracellular ATP signaling in equine digital blood vessels.  

PubMed

The functional distribution of ATP-activated P2 receptors is well characterized for many blood vessels, but not in the equine digital vasculature, which is a superficial vascular bed that displays thermoregulatory functions and has been implicated in ischemia-reperfusion injuries of the hoof. Isolated equine digital arteries (EDA) and veins (EDV) were submitted to isometric tension studies, whereby electric field stimulation (EFS) and concentration-response curves to exogenously applied agonists were constructed under low tone conditions. Additionally, immunofluorescent localization of P2X and P2Y receptor subtypes was performed. EFS-induced constriction was abolished by tetrodotoxin (1 ?M, n=4). Endothelium denudation did not modify the EFS-induced constriction (n=3). The EFS-induced constriction in EDA was inhibited by phentolamine (67.71.8%, n=6; 10 ?M), and by the non-selective P2 receptor antagonist suramin (46.21.3%, n=6; 10 ?M). EFS-induced constriction in EDV was reduced by suramin (48.22.4%, n=6; 10 ?M), the P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (58.34.5%, n=6; 10 ?M), and phentolamine (23.22.5%, n=6; 10 ?M). Exogenous methoxamine and ATP mimicked EFS-induced constriction in EDA and EDV. Immunostaining for P2X1, P2X2 and P2X3, and, for P2X1 and P2X7 receptor subunits were observed in EDA and EDV smooth muscle and adventitia, respectively. ATP and noradrenaline are co-transmitters in sympathetic nerves supplying the equine digital vasculature, noradrenaline being the dominant agonist in EDA, and ATP in EDV. In conclusion, P2X receptors mediate vasoconstriction in EDA and EDV, although different P2X subunits are involved in these vessels. The physiological significance of this finding in relation to thermoregulatory functions and equine laminitis is discussed. PMID:23370179

Zerpa, Hector; Crawford, Carol; Knight, Gillian E; Fordham, Alice F; Janska, Silvia E; Peppiatt-Wildman, Claire M; Elliott, Jonathan; Burnstock, Geoffrey; Wildman, Scott S

2013-02-28

112

A New Multiscale Representation for Shapes and Its Application to Blood Vessel Recovery  

E-print Network

In this paper, we will first introduce a novel multiscale representation (MSR) for shapes. Based on the MSR, we will then design a surface inpainting algorithm to recover 3D geometry of blood vessels. Because of the nature of irregular morphology in vessels and organs, both phantom and real inpainting scenarios were tested using our new algorithm. Successful vessel recoveries are demonstrated with numerical estimation of the degree of arteriosclerosis and vessel occlusion.

Bin Dong; Aichi Chien; Zuowei Shen; Stanley Osher

2009-05-20

113

A Rotating Cutting Tool to Remove Hard Cemented Deposits in Heart Blood Vessels without Damaging Soft Vessel Walls  

Microsoft Academic Search

A rotating cutting tool was developed to remove hard cemented deposits in the heart blood vessels without damaging the soft vessel walls. The new tool has a grater-like configuration which is made of anodized aluminum with 20|im high micro-blades on a 2mm diameter tip, and it rotates at 200,000 rpm underwater. An evaluation test demonstrated the feasibility of the new

M. Nakao; K. Tsuchiya; W. Maeda; D. Iijima

2005-01-01

114

Fluid Forces Combine with Molecular Signal to Trigger New Blood Vessel Growth | Physical Sciences in Oncology  

Cancer.gov

Angiogenesis, the growth of new blood vessels, is required for the development and spread of cancer, but the physical and biochemical factors that trigger this complex process are poorly understood. Using a microfluidic model of angiogenic sprouting, the initial visible step in new blood vessel formation, a pair of investigators from Harvard Medical School has shown that the sheer stress produced by flowing blood plays a critical role in early angiogenesis.

115

Transmitted Ultrasound Pressure Variation in Micro Blood Vessel Phantoms  

PubMed Central

Silica, cellulose, and polymethylmethacrylate tubes with inner diameters of ten to a few hundred microns are commonly used as blood vessel phantoms in in vitro studies of microbubble or nanodroplet behavior during insonation. However, a detailed investigation of the ultrasonic fields within these micro-tubes has not yet been performed. This technical note provides a theoretical analysis of the ultrasonic fields within micro-tubes. Numerical results show that for the same tube material, the interaction between the micro-tube and megaHertz-frequency ultrasound may vary drastically with incident frequency, tube diameter, and wall thickness. For 10 MHz ultrasonic insonation of a polymethylmethacrylate (PMMA) tube with an inner diameter of 195 ?m and an outer diameter of 260 ?m, the peak pressure within the tube can be up to 300% of incident pressure amplitude. However, using 1 MHz ultrasound and a silica tube with an inner diameter of 12 ?m and an outer diameter of 50 ?m, the peak pressure within the tube is only 12% of the incident pressure amplitude, and correspondingly the spatial-average-time-average intensity within the tube is only 1% of the incident intensity. PMID:18395962

Qin, Shengping; Kruse, Dustin E.; Ferrara, Katherine W.

2008-01-01

116

An in vivo Assay to Test Blood Vessel Permeability  

PubMed Central

This method is based on the intravenous injection of Evans Blue in mice as the test animal model. Evans blue is a dye that binds albumin. Under physiologic conditions the endothelium is impermeable to albumin, so Evans blue bound albumin remains restricted within blood vessels. In pathologic conditions that promote increased vascular permeability endothelial cells partially lose their close contacts and the endothelium becomes permeable to small proteins such as albumin. This condition allows for extravasation of Evans Blue in tissues. A healthy endothelium prevents extravasation of the dye in the neighboring vascularized tissues. Organs with increased permeability will show significantly increased blue coloration compared to organs with intact endothelium. The level of vascular permeability can be assessed by simple visualization or by quantitative measurement of the dye incorporated per milligram of tissue of control versus experimental animal/tissue. Two powerful aspects of this assay are its simplicity and quantitative characteristics. Evans Blue dye can be extracted from tissues by incubating a specific amount of tissue in formamide. Evans Blue absorbance maximum is at 620 nm and absorbance minimum is at 740 nm. By using a standard curve for Evans Blue, optical density measurements can be converted into milligram dye captured per milligram of tissue. Statistical analysis should be used to assess significant differences in vascular permeability. PMID:23524912

Radu, Maria; Chernoff, Jonathan

2013-01-01

117

Fpga based hardware synthesis for automatic segmentation of retinal blood vessels in diabetic retinopathy images.  

PubMed

Diabetic Retinopathy (DR) is a disorder that affects the structure of retinal blood vessels due to long-standing diabetes mellitus. Real-Time mass screening system for DR is vital for timely diagnosis and periodic screening to prevent the patient from severe visual loss. Human retinal fundus images are widely used for an automated segmentation of blood vessel and diagnosis of various blood vessel disorders. In this work, an attempt has been made to perform hardware synthesis of Kirsch template based edge detection for segmentation of blood vessels. This method is implemented using LabVIEW software and is synthesized in field programmable gate array board to yield results in real-time application. The segmentation of blood vessels using Kirsch based edge detection is compared with other edge detection methods such as Sobel, Prewitt and Canny. The texture features such as energy, entropy, contrast, mean, homogeneity and structural feature namely ratio of vessel to vessel free area are obtained from the segmented images. The performance of segmentation is analysed in terms of sensitivity, specificity and accuracy. It is observed from the results that the Kirsch based edge detection technique segmented the edges of blood vessels better than other edge detection techniques. The ratio of vessel to vessel free area classified the normal and DR affected retinal images more significantly than other texture based features. FPGA based hardware synthesis of Kirsch edge detection method is able to differentiate normal and diseased images with high specificity (93%). This automated segmentation of retinal blood vessels system could be used in computer-assisted diagnosis for diabetic retinopathy screening in real-time application. PMID:25405418

Sivakamasundari, J; Kavitha, G; Sujatha, C M; Ramakrishnan, S

2014-01-01

118

Investigating laser/blood-vessel interaction with color Doppler optical coherence tomography  

NASA Astrophysics Data System (ADS)

A non-invasive method of imaging laser irradiated blood vessels, and of tracking the healing response, has been achieved using Color Doppler Optical Coherence Tomography (CDOCT). This method may increase understanding of the mechanisms behind treatment of vascular disorders such as port wine stains. The CDOCT system uses a superluminescent diode with a center wavelength of 1280 nm. Pulsed dye and KTP lasers operating at 585 and 532 nm, respectively, were used to irradiate rat and hamster dorsal skin flap window models. The window model is a chronic preparation which exposes subdermal blood vessels while maintaining a thickness of normal skin. Irradiation sites were imaged with CDOCT prior to and immediately after laser irradiation, and at intervals up to several days following irradiation. The CDOCT signal was processed to provide both magnitude and color Doppler images. The Doppler signal provides an estimate of the blood flow velocity. The response of blood vessels to radiant exposures above and below the threshold for vessel coagulation was measured. An increase in the blood vessel backscattered signal was observed as blood and vessel walls were coagulated. Changes in blood flow velocity were noted in cases where vessels constricted or flow became occluded.

Barton, Jennifer K.; Izatt, Joseph A.; Welch, Ashley J.

1998-04-01

119

Sanford-Burnham study finds helping tumor blood vessels mature could make cancer drugs more effective  

Cancer.gov

To survive, tumors need blood supply to provide them with nutrients and oxygen. To get that supply, cancer cells stimulate new blood vessel growtha process called tumor angiogenesis. What if, rather than putting a stop to angiogenesis, we could help tumor blood vessels mature more completely, so tumor-killing therapies could more effectively reach their targets? In a paper published August 14 in the journal Cancer Cell, Sanford-Burnham researchers found a molecule that promotes the tumor vessel maturation processa discovery that might provide a method for improving cancer drug delivery.

120

A computational model predicting disruption of blood vessel development.  

PubMed

Vascular development is a complex process regulated by dynamic biological networks that vary in topology and state across different tissues and developmental stages. Signals regulating de novo blood vessel formation (vasculogenesis) and remodeling (angiogenesis) come from a variety of biological pathways linked to endothelial cell (EC) behavior, extracellular matrix (ECM) remodeling and the local generation of chemokines and growth factors. Simulating these interactions at a systems level requires sufficient biological detail about the relevant molecular pathways and associated cellular behaviors, and tractable computational models that offset mathematical and biological complexity. Here, we describe a novel multicellular agent-based model of vasculogenesis using the CompuCell3D (http://www.compucell3d.org/) modeling environment supplemented with semi-automatic knowledgebase creation. The model incorporates vascular endothelial growth factor signals, pro- and anti-angiogenic inflammatory chemokine signals, and the plasminogen activating system of enzymes and proteases linked to ECM interactions, to simulate nascent EC organization, growth and remodeling. The model was shown to recapitulate stereotypical capillary plexus formation and structural emergence of non-coded cellular behaviors, such as a heterologous bridging phenomenon linking endothelial tip cells together during formation of polygonal endothelial cords. Molecular targets in the computational model were mapped to signatures of vascular disruption derived from in vitro chemical profiling using the EPA's ToxCast high-throughput screening (HTS) dataset. Simulating the HTS data with the cell-agent based model of vascular development predicted adverse effects of a reference anti-angiogenic thalidomide analog, 5HPP-33, on in vitro angiogenesis with respect to both concentration-response and morphological consequences. These findings support the utility of cell agent-based models for simulating a morphogenetic series of events and for the first time demonstrate the applicability of these models for predictive toxicology. PMID:23592958

Kleinstreuer, Nicole; Dix, David; Rountree, Michael; Baker, Nancy; Sipes, Nisha; Reif, David; Spencer, Richard; Knudsen, Thomas

2013-04-01

121

A Computational Model Predicting Disruption of Blood Vessel Development  

PubMed Central

Vascular development is a complex process regulated by dynamic biological networks that vary in topology and state across different tissues and developmental stages. Signals regulating de novo blood vessel formation (vasculogenesis) and remodeling (angiogenesis) come from a variety of biological pathways linked to endothelial cell (EC) behavior, extracellular matrix (ECM) remodeling and the local generation of chemokines and growth factors. Simulating these interactions at a systems level requires sufficient biological detail about the relevant molecular pathways and associated cellular behaviors, and tractable computational models that offset mathematical and biological complexity. Here, we describe a novel multicellular agent-based model of vasculogenesis using the CompuCell3D (http://www.compucell3d.org/) modeling environment supplemented with semi-automatic knowledgebase creation. The model incorporates vascular endothelial growth factor signals, pro- and anti-angiogenic inflammatory chemokine signals, and the plasminogen activating system of enzymes and proteases linked to ECM interactions, to simulate nascent EC organization, growth and remodeling. The model was shown to recapitulate stereotypical capillary plexus formation and structural emergence of non-coded cellular behaviors, such as a heterologous bridging phenomenon linking endothelial tip cells together during formation of polygonal endothelial cords. Molecular targets in the computational model were mapped to signatures of vascular disruption derived from in vitro chemical profiling using the EPA's ToxCast high-throughput screening (HTS) dataset. Simulating the HTS data with the cell-agent based model of vascular development predicted adverse effects of a reference anti-angiogenic thalidomide analog, 5HPP-33, on in vitro angiogenesis with respect to both concentration-response and morphological consequences. These findings support the utility of cell agent-based models for simulating a morphogenetic series of events and for the first time demonstrate the applicability of these models for predictive toxicology. PMID:23592958

Kleinstreuer, Nicole; Dix, David; Rountree, Michael; Baker, Nancy; Sipes, Nisha; Reif, David; Spencer, Richard; Knudsen, Thomas

2013-01-01

122

Numerical investigation of hyperelastic wall deformation characteristics in a micro-scale stenotic blood vessel  

NASA Astrophysics Data System (ADS)

Stenosis is the drastic reduction of blood vessel diameter because of cholesterol accumulation in the vessel wall. In addition to the changes in blood flow characteristics, significant changes occur in the mechanical behavior of a stenotic blood vessel. We conducted a 3-D study of such behavior in micro-scale blood vessels by considering the fluid structure interaction between blood flow and vessel wall structure. The simulation consisted of one-way coupled analysis of blood flow and the resulting structural deformation without a moving mesh. A commercial code based on a finite element method with a hyperelastic material model (Neo-Hookean) of the wall was used to calculate wall deformation. Three different cases of stenosis severity and aspect ratios with and without muscles around the blood vessel were considered. The results showed that the wall deformation in a stenotic channel is directly related to stenosis severity and aspect ratio. The presence of muscles reduces the degree of deformation even in very severe stenosis.

Cheema, Taqi Ahmad; Park, Cheol Woo

2013-08-01

123

SIMULATION OF DISCRETE BLOOD VESSEL EFFECTS ON THE THERMAL SIGNATURE OF A MELANOMA LESION.  

PubMed

The effect of the underlying blood vessel on the transient thermal response of the skin surface with and without a melanoma lesion is studied. A 3D computational model of the layers of the skin tissue with cancerous lesion was developed in COMSOL software package. Heat transfer in the skin layers and the lesion is governed by the Pennes bio-heat equation, while the blood vessel is modeled as fully developed pipe flow with constant heat transfer coefficient. The effect of various pertinent parameters, such as diameter of the blood vessel, lateral location of the blood vessel relative to the lesion, flow velocity of the blood, on the skin surface temperature distribution, have been studied in the paper. The results show significant influence of the underlying blood vessel on the temperature of the skin surface and lesion as well as on the surrounding healthy tissue. Thus, a need for development of evaluation criteria for detection of malignant lesions in the presence of blood vessels is is discussed. PMID:25328916

Kandala, Sri Kamal; Deng, Daxiang; Herman, Cila

2013-01-01

124

Mouse blood vessel imaging by in-line x-ray phase-contrast imaging  

Microsoft Academic Search

It is virtually impossible to observe blood vessels by conventional x-ray imaging techniques without using contrast agents. In addition, such x-ray systems are typically incapable of detecting vessels with diameters less than 200 m. Here we show that vessels as small as 30 m could be detected using in-line phase-contrast x-ray imaging without the use of contrast agents. Image quality

Xi Zhang; Xiao-Song Liu; Xin-Rong Yang; Shao-Liang Chen; Pei-Ping Zhu; Qing-Xi Yuan

2008-01-01

125

Temperature evolution in tissues embedded with large blood vessels during photo-thermal heating.  

PubMed

During laser-assisted photo-thermal therapy, the temperature of the heated tissue region must rise to the therapeutic value (e.g., 43C) for complete ablation of the target cells. Large blood vessels (larger than 500 micron in diameter) at or near the irradiated tissues have a considerable impact on the transient temperature distribution in the tissue. In this study, the cooling effects of large blood vessels on temperature distribution in tissues during laser irradiation are predicted using finite element based simulation. A uniform flow is assumed at the entrance and three-dimensional conjugate heat transfer equations in the tissue region and the blood region are simultaneously solved for different vascular models. A volumetric heat source term based on Beer-Lambert law is introduced into the energy equation to account for laser heating. The heating pattern is taken to depend on the absorption and scattering coefficients of the tissue medium. Experiments are also conducted on tissue mimics in the presence and absence of simulated blood vessels to validate the numerical model. The coupled heat transfer between thermally significant blood vessels and their surrounding tissue for three different tissue-vascular networks are analyzed keeping the laser irradiation constant. A surface temperature map is obtained for different vascular models and for the bare tissue (without blood vessels). The transient temperature distribution is seen to differ according to the nature of the vascular network, blood vessel size, flow rate, laser spot size, laser power and tissue blood perfusion rate. The simulations suggest that the blood flow through large blood vessels in the vicinity of the photothermally heated tissue can lead to inefficient heating of the target. PMID:24679976

Paul, Anup; Narasimhan, Arunn; Kahlen, Franz J; Das, Sarit K

2014-04-01

126

Angiotensin inhibition enhances drug delivery and potentiates chemotherapy by decompressing tumour blood vessels  

E-print Network

Cancer and stromal cells actively exert physical forces (solid stress) to compress tumour blood vessels, thus reducing vascular perfusion. Tumour interstitial matrix also contributes to solid stress, with hyaluronan ...

Chauhan, Vikash P.

127

Automatic Detection of Blood Vessels in Retinal Images for Diabetic Retinopathy Diagnosis  

PubMed Central

Diabetic retinopathy (DR) is a leading cause of vision loss in diabetic patients. DR is mainly caused due to the damage of retinal blood vessels in the diabetic patients. It is essential to detect and segment the retinal blood vessels for DR detection and diagnosis, which prevents earlier vision loss in diabetic patients. The computer aided automatic detection and segmentation of blood vessels through the elimination of optic disc (OD) region in retina are proposed in this paper. The OD region is segmented using anisotropic diffusion filter and subsequentially the retinal blood vessels are detected using mathematical binary morphological operations. The proposed methodology is tested on two different publicly available datasets and achieved 93.99% sensitivity, 98.37% specificity, 98.08% accuracy in DRIVE dataset and 93.6% sensitivity, 98.96% specificity, and 95.94% accuracy in STARE dataset, respectively.

Siva Sundhara Raja, D.; Vasuki, S.

2015-01-01

128

Label-free imaging of blood vessel morphology with capillary resolution using optical microangiography  

PubMed Central

Several tissue pathologies are correlated with changes in the blood vessel morphology and microcirculation that supplies the tissue. Optical coherence tomography (OCT) is an imaging technique that enables acquiring non-invasive three-dimensional images of biological structures with micrometer resolution. Optical microangiography (OMAG) is a method of processing OCT data which enables visualizing the three-dimensional blood vessel morphology within biological tissues. OMAG has high spatial resolution which allows visualizing single capillary vessels, and does not require the use of contrast agents. The intrinsic optical signals backscattered by the moving blood cells inside blood vessels are used as the contrast for which OMAG images are based on. In this paper, we discuss a brief review of the OMAG theory, and present some examples of applications for this technique. PMID:23256081

Reif, Roberto

2012-01-01

129

Disclosure of the significant thermal effects of large blood vessels during cryosurgery through infrared temperature mapping  

Microsoft Academic Search

During cryosurgery the large blood vessels entering the frozen volume can be an important source of temperature non-uniformity and possible under-dosage for the target tissues. In this study, the thermal effects of large vessels during cryosurgery were experimentally investigated by introducing infrared thermography system on monitoring both simulated and animal experiments. For all experiments, the freezing was supplied by a

Zhong-Shan Deng; Jing Liu; Hong-Wu Wang

2008-01-01

130

Characterization of changes in blood vessel width and tortuosity in retinopathy of prematurity using image analysis  

Microsoft Academic Search

Many retinal diseases are characterised by changes to retinal vessels. For example, a common condition associated with retinopathy of prematurity (ROP) is so-called plus disease, characterised by increased vascular dilation and tortuosity. This paper presents a general technique for segmenting out vascular structures in retinal images, and characterising the segmented blood vessels. The segmentation technique consists of several steps. Morphological

Conor Heneghan; John Flynn; Michael OKeefe; Mark Cahill

2002-01-01

131

Estimation of Blood Flow Speed and Vessel Location from Thermal Video M. Garbey A. Merla  

E-print Network

the thermo-physiological processes in a skin region proximal to a major vessel. The model assumes the form. In this paper we focus on the computation of blood flow properties in vessels proximal to the skin. We use or some type of contact sensing, like Doppler ultrasound probe. Since we are interested in bioheat

132

In vitro and in vivo application of PLGA nanofiber for artificial blood vessel  

Microsoft Academic Search

Poly(lactic-co-glycolic acid) (PLGA) tubes (5 mm in diameter) were fabricated using an electro spinning method and used as a scaffold for\\u000a artificial blood vessels through the hybridization of smooth muscle cells (SMCs) and endothelial cells (ECs) differentiated\\u000a from canine bone marrow under previously reported conditions. The potential clinical applications of these artificial blood\\u000a vessels were investigated using a canine model.

Mi Jin Kim; Ji-Heung Kim; Gijong Yi; Sang-Hyun Lim; You Sun Hong; Dong June Chung

2008-01-01

133

Visualisation of blood and lymphatic vessels with increasing exposure time of the detector  

NASA Astrophysics Data System (ADS)

We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions.

Kalchenko, V. V.; Kuznetsov, Yu L.; Meglinski, I. V.

2013-07-01

134

Visualisation of blood and lymphatic vessels with increasing exposure time of the detector  

SciTech Connect

We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions. (laser applications in biology and medicine)

Kalchenko, V V; Kuznetsov, Yu L; Meglinski, I V

2013-07-31

135

Development of blood vessel search system using near-infrared light for laparoscopic surgery  

NASA Astrophysics Data System (ADS)

Our objective of this study is to develop a miniature and high accuracy automatic 3D blood vessel searching system, which will be introduced in the laparoscopic operation with the minimally invasive surgery. Now, the conventional optical system used in the laparoscopic surgery has many difficulties of blood vessel imaging and detection, because the peripheral bio-tissue located around the blood vessel disturbs the light wave propagation, disperses and refracts. Consequently, only unclear image is obtained. We develop a new blood vessel detecting system by using Near-Infrared (NIR) light, two CMOS camera modules and a comprehensive image processing technique, which is implemented in the laparoscope pipe with 25mm in diameter. We adopt the stereo method for the searching system to determine 3D blood vessel location. The blood vessel visualization system adopts hemoglobin's absorption characteristics of the NIR light, which has high permeability for the bio-tissue and absorbency for the hemoglobin. A sharpening process is employed to improve the image quality of original ones, through the LoG filter and the un-sharp-mask processing. 2D location of the blood vessel is calculated from luminance distribution of the image and its depth is calculated by the stereo method. A validity of our blood vessel visualization and 3D detecting system was examined through the comparison with the imaging and detecting the results of organization phantoms, which embedded at known depths under the surface. Experimental results of depth obtained by our detecting system showed good agreements with the given depths, and the availability of this system is confirmed.

Narita, K.; Nakamachi, E.; Morita, Y.; Hagiwara, A.

2013-09-01

136

Multi-scale transparent arteriole and capillary vessel models for circulation type blood vessel simulator  

Microsoft Academic Search

We proposed a fabrication method for multiscale transparent arteriole and capillary vessel models and demonstrated the fabrication of microchannels with circular cross sections 10 - 500 m. First, we demonstrated fabrication of 10 - 500 m arteriole and capillary vessel block models using photolithography. The circularity of fabricated 10, 50, and 500 m microchannels were 84.0%, 61.5%, and 82.3%, respectively.

Takuma Nakano; Keisuke Yoshida; Seiichi Ikeda; Hiroyuki Oura; Toshio Fukuda; Takehisa Matsuda; Makoto Negoro; Fumihito Arai

2009-01-01

137

Mechanisms of the Formation and Stability of Retinal Blood Vessels  

Microsoft Academic Search

As an introduction, we restate briefly several major themes of retinal vascularization. All have been reviewed previously.\\u000a Some are common to the formation of vessels in any tissue; others are unique to the eye.

Jonathan Stone; Trent Sandercoe; Jan Provis

138

Prevent Diabetes Problems: Keep Your Heart and Blood Vessels Healthy  

MedlinePLUS

... vessel problems. [ Top ] What should I do each day to stay healthy with diabetes? Follow the healthy ... Be active a total of 30 minutes most days. Ask your doctor what activities are best for ...

139

Blood Flow At Arterial Branches: Complexities To Resolve For The Angioplasty Suite  

E-print Network

Blood Flow At Arterial Branches: Complexities To Resolve For The Angioplasty Suite P.D. Richardson1 the flows in a branched artery, to compare them with prior physical flow visualization, and to interpret them with further users in mind. The geometry was taken for a typical epicardial coronary artery

Laidlaw, David

140

Growth and Remodeling in Blood Vessels Studied In Vivo With Fractal Analysis  

NASA Technical Reports Server (NTRS)

Every cell in the human body must reside in close proximity to a blood vessel (within approximately 200 mm) because blood vessels provide the oxygen, metabolite, and fluid exchanges required for cellular existence. The growth and remodeling of blood vessels are required to support the normal physiology of embryonic development, reproductive biology, wound healing and adaptive remodeling to exercise, as well as abnormal tissue change in diseases such as cancer, diabetes, and coronary heart disease. Cardiovascular and hemodynamic (blood flow dynamics) alterations experienced by astronauts during long-term spaceflight, including orthostatic intolerance, fluid shifts in the body, and reduced numbers of red (erythrocyte) and white (immune) blood cells, are identified as risk factors of very high priority in the NASA task force report on risk reduction for human spaceflight, the "Critical Path Roadmap."

Parsons-Wingerter, Patricia A.

2003-01-01

141

Label free in vivo laser speckle imaging of blood and lymph vessels  

NASA Astrophysics Data System (ADS)

The peripheral lymphatic vascular system is a part of the immune body system comprising a complex network of lymph vessels and nodes that are flowing lymph toward the heart. Traditionally the imaging of lymphatic vessels is based on the conventional imaging modalities utilizing contrast fluorescence materials. Given the important role of the lymphatic system there is a critical need for the development of noninvasive imaging technologies for functional quantitative diagnosis of the lymph vessels and lymph flow without using foreign chemicals. We report a label free methodology for noninvasive in vivo imaging of blood and lymph vessels, using long-exposure laser speckle imaging approach. This approach entails great promise in the noninvasive studies of tissues blood and lymph vessels distribution in vivo.

Kalchenko, Vyacheslav; Kuznetsov, Yuri; Meglinski, Igor; Harmelin, Alon

2012-05-01

142

Proteomic profiling of tissue-engineered blood vessel walls constructed by adipose-derived stem cells.  

PubMed

Adipose-derived stem cells (ASCs) can differentiate into smooth muscle cells and have been engineered into elastic small diameter blood vessel walls in vitro. However, the mechanisms involved in the development of three-dimensional (3D) vascular tissue remain poorly understood. The present study analyzed protein expression profiles of engineered blood vessel walls constructed by human ASCs using methods of two-dimensional gel electrophoresis (2DE) and mass spectrometry (MS). These results were compared to normal arterial walls. A total of 170115 and 126526 protein spots from normal and engineered blood vessel wall extractions were detected by 2DE, respectively. A total of 20 spots with at least 2.0-fold changes in expression were identified, and 38 differently expressed proteins were identified by 2D electrophoresis and ion trap MS. These proteins were classified into seven functional categories: cellular organization, energy, signaling pathway, enzyme, anchored protein, cell apoptosis/defense, and others. These results demonstrated that 2DE, followed by ion trap MS, could be successfully utilized to characterize the proteome of vascular tissue, including tissue-engineered vessels. The method could also be employed to achieve a better understanding of differentiated smooth muscle protein expression in vitro. These results provide a basis for comparative studies of protein expression in vascular smooth muscles of different origin and could provide a better understanding of the mechanisms of action needed for constructing blood vessels that exhibit properties consistent with normal blood vessels. PMID:22963350

Wang, Chen; Guo, Fangfang; Zhou, Heng; Zhang, Yun; Xiao, Zhigang; Cui, Lei

2013-02-01

143

Blood Vessel Contributions to Retinal Nerve Fiber Layer Thickness Profiles Measured With Optical Coherence Tomography  

PubMed Central

Purpose To understand better the influence of retinal blood vessels (BVs) on the interindividual variation in the retinal nerve fiber layer (RNFL) thickness measured with optical coherence tomography (OCT). Subjects and Methods RNFL thickness profiles were measured by OCT in 16 control individuals and 16 patients. The patients had advanced glaucoma defined by abnormal disc appearance, abnormal visual fields, and a mean visual field deviation worse than ? 10 dB. Results In general, the OCT RNFL thickness profiles showed 4 local maxima, with the peak amplitudes in the superior and inferior regions occurring in the temporal (peripapillary) disc region. There was considerable variability among individuals in the location of these maxima. However, the 4 maxima typically fell on, or near, a major BV with the temporal and inferior peaks nearly always associated with the main temporal branches of the superior and inferior veins and arteries. In the patients hemifields with severe loss (mean visual field deviation worse than ? 20 dB), the signals associated with the major BVs were in the order of 100 to 150 m. Conclusions The variation in the local peaks of the RNFL profiles of controls correlates well with the location of the main temporal branches of the superior and inferior veins and arteries. This correspondence is, in part, due to a direct BV contribution to the shape of the OCT RNFL and, in part, due to the fact that BVs develop along the densest regions of axons. Although the overall BV contribution was estimated to be relatively modest, roughly 13% of the total peripapillary RNFL thickness in controls, their contribution represents a substantial portion locally and increases in importance with disease progression. PMID:18854727

Hood, Donald C.; Fortune, Brad; Arthur, Stella N.; Xing, Danli; Salant, Jennifer A.; Ritch, Robert; Liebmann, Jeffrey M.

2010-01-01

144

Vasodilator effects of ibudilast on retinal blood vessels in anesthetized rats.  

PubMed

Ibudilast (3-isobutyryl-2-isopropylpyrazolo[1,5-alpha]pyridine) is clinically used as a cerebral vasodilator in Japan. However, the effects of ibudilast on retinal blood vessels have not been fully examined. The aim of this study, therefore, was to examine the effects of ibudilast on retinal blood vessels in rats in vivo. Male Wistar rats (8 to 10 weeks old) were anesthetized with thiobutabarbital (120 mg/kg, intraperitoneally (i.p.)). Retinal vascular images were captured with a fundus camera system for small animals, and the diameter of retinal blood vessels was measured. Ibudilast (0.1 and 1 mg/kg, intravenously (i.v.)) elicited a sustained increase in the diameter of retinal blood vessels and heart rate without altering systemic blood pressure. The effects of ibudilast were significantly reduced by treatment with the nonselective cyclooxygenase inhibitor indomethacin (5 mg/kg, i.p.). These results suggest that ibudilast dilates retinal blood vessels through cyclooxygenase-dependent mechanisms in rats in vivo. PMID:19881310

Noguchi, Masahiro; Mori, Asami; Sakamoto, Kenji; Nakahara, Tsutomu; Ishii, Kunio

2009-11-01

145

An experimental system for the study of ultrasound exposure of isolated blood vessels  

NASA Astrophysics Data System (ADS)

An experimental system designed for the study of the effects of diagnostic or therapeutic ultrasound exposure on isolated blood vessels in the presence or absence of intraluminal contrast agent is described. The system comprised several components. A microscope was used to monitor vessel size (and thus vessel functionality), and potential leakage of intraluminal 70 kDa FITC-dextran fluorescence marker. A vessel chamber allowed the mounting of an isolated vessel whilst maintaining its viability, with pressure regulation for the control of intraluminal pressure and induction of flow for the infusion of contrast microbubbles. A fibre-optic hydrophone sensor mounted on the vessel chamber using a micromanipulator allowed pre-exposure targeting of the vessel to within 150 m, and monitoring of acoustic cavitation emissions during exposures. Acoustic cavitation was also detected using changes in the ultrasound drive voltage and by detection of audible emissions using a submerged microphone. The suitability of this system for studying effects in the isolated vessel model has been demonstrated using a pilot study of 6 sham exposed and 18 high intensity focused ultrasound exposed vessels, with or without intraluminal contrast agent (SonoVue) within the vessels.

Tokarczyk, Anna; Rivens, Ian; van Bavel, E.; Symonds-Tayler, Richard; ter Haar, Gail

2013-04-01

146

Analysis of the Effect of Partial Vitrification on Stress Development in Cryopreserved Blood Vessels  

PubMed Central

Thermal stress development in blood vessels, during processes associated with vitrification (vitreous means glassy in Latin), is studied. This paper addresses the limiting case where the specimen completely crystallizes, while the cryoprotectant medium (CPA) completely vitrifies. This case is expected to provide upper boundary estimates for stresses for the more common problem of a partially vitrified sample. The CPA is modeled as a linear viscoelastic medium, with viscosity increasing exponentially with decreasing temperature; given the assumption of complete crystallization, the blood vessel is modeled as linear elastic below the freezing temperature. Consistent with previous observations, the CPA is found to behave linear elastically below a set-temperature, at which point the viscosity rises sufficiently quickly with further cooling. This observation reduces computational efforts and allows for parametric studies based on suitably chosen wholly elastic models. Both 2D concentric cylinder models of the blood vessel in a straight configuration and a 3D model of the vessel curled in a vial of CPA are studied; 2D models are shown to bound the results of the more general 3D problem. It is found that stress in the CPA decreases with increase in CPA volume, at least under conditions where the temperature can be viewed as uniform. Planar cracks are predicted to form transverse to the vessel axis, and to propagate right up to the blood vessel wall. Should such cracks propagate into the vessel, even over only a few ?m, the mechanical damage to the lumen, or to endothelial cells, may cause the blood vessel to completely loose its functionality at the end of the cryopreservation protocol. PMID:16996295

Steif, Paul S.; Palastro, Matthew C.; Rabin, Yoed

2007-01-01

147

Differentiating Blood, Lymph, and Primo Vessels by Residual Time Characteristic of Fluorescent Nanoparticles in a Tumor Model  

PubMed Central

Fluorescent nanoparticles (FNPs) which were injected into a tumor tissue flowed out through the blood and lymph vessels. The FNPs in blood vessels remained only in the order for few minutes while those in lymph vessels remained for a long time disappearing completely in 25 hours. We found a primo vessel inside a lymph vessel near a blood vessel, and FNPs remained in the primo vessel for longer than 25 hours. In addition, we examined in detail the residual time characteristics of lymph vessels because it could be useful in a future study of fluid dynamical comparison of the three conduits. These residual time characteristics of FNPs in the three kinds of vessels may have implications for the dynamics of nanoparticle drugs for cancer chemotherapy. PMID:23662147

Lee, Sungwoo; Lim, Jaekwan; Cha, Jinmyung; Lee, Jin-Kyu; Ryu, Yeon Hee; Kim, SungChul; Soh, Kwang-Sup

2013-01-01

148

Blood vessel adaptation to gravity in a semi-arboreal snake  

NASA Technical Reports Server (NTRS)

The effects of vasoactive agonists on systemic blood vessels were examined with respect to anatomical location and gravity acclimation in the semi-arboreal snake, Elaphe Obsoleta. Major blood vessels were reactive to putative neurotransmitters, hormones or local factors in vessel specific patterns. Catecholamines, adenosine triphosphate, histamine and high potassium (80 mM) stimulated significantly greater tension per unit vessel mass in posterior than anterior arteries. Anterior vessels were significantly more sensitive to catecholamines than midbody and posterior vessels. Angiotensin II stimulated significantly greater tension in carotid artery than in midbody and posterior dorsal aorta. Arginine vasotocin strongly contracted the left and right aortic arches and anterior dorsal aorta. Veins were strongly contracted by catecholamines, high potassium and angiotensin II, but less so by adenosine triphosphate, arginine vasotocin and histamine. Precontracted vessel were relaxed by acetylcholine and sodium nitroprusside, but not by atrial natriuretic peptide or bradykinin. Chronic exposure of snakes to intermittent hypergravity stress ( + 1.5 Gz at tail) did not affect the majority of vessel responses. These data demonstrate that in vitro tension correlates with that catecholamines, as well as other agonists, are important in mediating vascular responses to gravitational stresses in snakes.

Conklin, D. J.; Lillywhite, H. B.; Olson, K. R.; Ballard, R. E.; Hargens, A. R.

1996-01-01

149

Effects of histidine-rich glycoprotein on cerebral blood vessels.  

PubMed

Delayed cerebral vasospasm is thought to be caused by factors released from a subarachnoid blood clot. Because vasospasm occurs several days after hemorrhage, we hypothesized that clotted blood releases vasoactive factors as it ages. Targeted proteomics identified histidine-rich glycoprotein (HRG) as a potentially vasoactive factor released within the first 72 hours of clot formation. In vitro studies revealed that HRG caused moderate (~30%) dilation of cannulated cerebral arterioles and proliferation of cerebrovascular endothelial cells. We conclude that HRG released from clotted blood, while unlikely to contribute to cerebral vasospasm, might provide important vasodilatory or angiogenic stimuli after hemorrhagic stroke. PMID:23801240

Steelman, Samantha M; Hein, Travis W; Gorman, Amy; Bix, Gregory J

2013-09-01

150

Effects of histidine-rich glycoprotein on cerebral blood vessels  

PubMed Central

Delayed cerebral vasospasm is thought to be caused by factors released from a subarachnoid blood clot. Because vasospasm occurs several days after hemorrhage, we hypothesized that clotted blood releases vasoactive factors as it ages. Targeted proteomics identified histidine-rich glycoprotein (HRG) as a potentially vasoactive factor released within the first 72?hours of clot formation. In vitro studies revealed that HRG caused moderate (?30%) dilation of cannulated cerebral arterioles and proliferation of cerebrovascular endothelial cells. We conclude that HRG released from clotted blood, while unlikely to contribute to cerebral vasospasm, might provide important vasodilatory or angiogenic stimuli after hemorrhagic stroke. PMID:23801240

Steelman, Samantha M; Hein, Travis W; Gorman, Amy; Bix, Gregory J

2013-01-01

151

Complementary actions of VEGF and Angiopoietin-1 on blood vessel growth and leakage*  

PubMed Central

Vascular endothelial growth factor (VEGF) and Angiopoietins are families of vascular-specific growth factors that regulate blood vessel growth, maturation and function. To learn more about the effects of these factors in vivo, we have overexpressed VEGF-A or Angiopoietin-1 (Ang1) in two systems in mice, and examined the effects on blood vessel growth and function. In one set of studies, VEGF, Ang1, or both factors, were transgenically overexpressed in the skin under the keratin-14 (K14) promoter. The skin of mice overexpressing VEGF (K14-VEGF) had numerous tortuous, capillary-sized vessels which were leaky to the plasma tracer Evans blue under baseline conditions. In contrast, the skin of mice overexpressing Ang1 (K14-Ang1) had enlarged dermal vessels without a significant increase in vessel number. These enlarged vessels were less leaky than those of wild-type mice in response to inflammatory stimuli. In double transgenic mice overexpressing VEGF and Ang1, the size and number of skin vessels were both increased; however, the vessels were not leaky. In a second set of studies, VEGF or Ang1 was systemically delivered using an adenoviral approach. Intravenous injection of adenovirus encoding VEGF (Adeno-VEGF) resulted in widespread tissue oedema within 12 days after administration, whereas injection of Adeno-Ang1 resulted in the skin vessels becoming less leaky in response to topical inflammatory stimuli or local injection of VEGF. The decreased leakage was not accompanied by morphological changes. Thus, overexpressing VEGF appears to promote growth of new vessels accompanied by plasma leakage, whereas overexpressing Ang1 promotes the enlargement of existing vessels and a resistance to leakage. Further understanding of the interrelationship of these factors during normal development could lead to their application in the treatment of ischaemic diseases. PMID:12162725

Thurston, Gavin

2002-01-01

152

Decellularized tissue-engineered blood vessel as an arterial conduit  

PubMed Central

Arterial tissue-engineering techniques that have been reported previously typically involve long waiting times of several months while cells from the recipient are cultured to create the engineered vessel. In this study, we developed a different approach to arterial tissue engineering that can substantially reduce the waiting time for a graft. Tissue-engineered vessels (TEVs) were grown from banked porcine smooth muscle cells that were allogeneic to the intended recipient, using a biomimetic perfusion system. The engineered vessels were then decellularized, leaving behind the mechanically robust extracellular matrix of the graft wall. The acellular grafts were then seeded with cells that were derived from the intended recipienteither endothelial progenitor cells (EPC) or endothelial cell (EC)on the graft lumen. TEV were then implanted as end-to-side grafts in the porcine carotid artery, which is a rigorous testbed due to its tendency for graft occlusion. The EPC- and EC-seeded TEV all remained patent for 30 d in this study, whereas the contralateral control vein grafts were patent in only 3/8 implants. Going along with the improved patency, the cell-seeded TEV demonstrated less neointimal hyperplasia and fewer proliferating cells than did the vein grafts. Proteins in the mammalian target of rapamycin signaling pathway tended to be decreased in TEV compared with vein grafts, implicating this pathway in the TEV's resistance to occlusion from intimal hyperplasia. These results indicate that a readily available, decellularized tissue-engineered vessel can be seeded with autologous endothelial progenitor cells to provide a biological vascular graft that resists both clotting and intimal hyperplasia. In addition, these results show that engineered connective tissues can be grown from banked cells, rendered acellular, and then used for tissue regeneration in vivo. PMID:21571635

Quint, Clay; Kondo, Yuka; Manson, Roberto J.; Lawson, Jeffrey H.; Dardik, Alan; Niklason, Laura E.

2011-01-01

153

Aging changes in the heart and blood vessels  

MedlinePLUS

... lungs to receive oxygen and get rid of carbon dioxide. The left side pumps oxygen-rich blood to ... oxygen and nutrients to the tissues, and receives carbon dioxide and wastes back from the tissues. Then, the ...

154

TOPAZ: a computer code for modeling heat transfer and fluid flow in arbitrary networks of pipes, flow branches, and vessels  

SciTech Connect

An overview of the computer code TOPAZ (Transient-One-Dimensional Pipe Flow Analyzer) is presented. TOPAZ models the flow of compressible and incompressible fluids through complex and arbitrary arrangements of pipes, valves, flow branches and vessels. Heat transfer to and from the fluid containment structures (i.e. vessel and pipe walls) can also be modeled. This document includes discussions of the fluid flow equations and containment heat conduction equations. The modeling philosophy, numerical integration technique, code architecture, and methods for generating the computational mesh are also discussed.

Winters, W.S.

1984-01-01

155

A novel scheme for nanoparticle steering in blood vessels using a functionalized magnetic field.  

PubMed

Magnetic drug targeting is a drug delivery approach in which therapeutic magnetizable particles are injected, generally into blood vessels, and magnets are then used to guide and concentrate them in the diseased target organ. Although many analytical, simulation, and experimental studies on capturing schemes for drug targeting have been conducted, there are few studies on delivering the nanoparticles to the target region. Furthermore, the sticking phenomenon of particles to vessels walls near the injection point, and far from the target region, has not been addressed sufficiently. In this paper, the sticking issue and its relationship to nanoparticle steering are investigated in detail using numerical simulations. For wide ranges of blood vessel size, blood velocity, particle size, and applied magnetic field, three coefficient numbers are uniquely generalized: vessel elongation, normal exit time, and force rate. With respect these new parameters, we investigated particle distribution trends for a Y-shaped channel and computed ratios of correctly guided particles and particles remaining in the vessel. We found that the sticking of particles to vessels occurred because of low blood flow velocity near the vessel walls, which is the main reason for low targeting efficiency when using a constant magnetic gradient. To reduce the sticking ratio of nanoparticles, we propose a novel field function scheme that uses a simple time-varying function to separate the particles from the walls and guide them to the target point. The capabilities of the proposed scheme were examined by several simulations of both Y-shaped channels and realistic three-dimensional (3-D) model channels extracted from brain vessels. The results showed a significant decrease in particle adherence to walls during the delivery stage and confirmed the effectiveness of the proposed magnetic field function method for steering nanoparticles for targeted drug delivery. PMID:25163053

Tehrani, Mohammad Dadkhah; Yoon, Jong-Hwan; Kim, Myeong Ok; Yoon, Jungwon

2015-01-01

156

Relationships between Age, Blood Pressure, and Retinal Vessel Diameters in an Older Population  

Microsoft Academic Search

PURPOSE. To describe the cross-sectional relationships between age, blood pressure (BP), and quantitative measures of retinal vessel diameters in an older Australian population. METHODS. Retinal photographs from right eyes of partici- pants (n 3654, aged 49 years) in the Blue Mountains Eye study taken during baseline examinations (1992-1994) were digitized. The width of all retinal vessels located 0.5 to 1.0

Harry Leung; Jie Jin Wang; Elena Rochtchina; Ava G. Tan; Tien Y. Wong; Ronald Klein; Larry D. Hubbard; Paul Mitchell

157

Use of the retinal vessel analyzer in ocular blood flow research.  

PubMed

The present article describes a standard instrument for the continuous online determination of retinal vessel diameters, the commercially available retinal vessel analyzer. This report is intended to provide informed guidelines for measuring ocular blood flow with this system. The report describes the principles underlying the method and the instruments currently available, and discusses clinical protocol and the specific parameters measured by the system. Unresolved questions and the possible limitations of the technique are also discussed. PMID:19681764

Garhofer, Gerhard; Bek, Toke; Boehm, Andreas G; Gherghel, Doina; Grunwald, Juan; Jeppesen, Peter; Kergoat, Hlne; Kotliar, Konstantin; Lanzl, Ines; Lovasik, John V; Nagel, Edgar; Vilser, Walthard; Orgul, Selim; Schmetterer, Leopold

2010-11-01

158

New algorithm for detecting smaller retinal blood vessels in fundus images  

NASA Astrophysics Data System (ADS)

About 4.1 million Americans suffer from diabetic retinopathy. To help automatically diagnose various stages of the disease, a new blood-vessel-segmentation algorithm based on spatial high-pass filtering was developed to automatically segment blood vessels, including the smaller ones, with low noise. Methods: Image database: Forty, 584 x 565-pixel images were collected from the DRIVE image database. Preprocessing: Green-band extraction was used to obtain better contrast, which facilitated better visualization of retinal blood vessels. A spatial highpass filter of mask-size 11 was applied. A histogram stretch was performed to enhance contrast. A median filter was applied to mitigate noise. At this point, the gray-scale image was converted to a binary image using a binary thresholding operation. Then, a NOT operation was performed by gray-level value inversion between 0 and 255. Postprocessing: The resulting image was AND-ed with its corresponding ring mask to remove the outer-ring (lens-edge) artifact. At this point, the above algorithm steps had extracted most of the major and minor vessels, with some intersections and bifurcations missing. Vessel segments were reintegrated using the Hough transform. Results: After applying the Hough transform, both the average peak SNR and the RMS error improved by 10%. Pratt's Figure of Merit (PFM) was decreased by 6%. Those averages were better than [1] by 10-30%. Conclusions: The new algorithm successfully preserved the details of smaller blood vessels and should prove successful as a segmentation step for automatically identifying diseases that affect retinal blood vessels.

LeAnder, Robert; Bidari, Praveen I.; Mohammed, Tauseef A.; Das, Moumita; Umbaugh, Scott E.

2010-03-01

159

Combining cell sheet technology and electrospun scaffolding for engineered tubular, aligned, and contractile blood vessels.  

PubMed

Herein we combine cell sheet technology and electrospun scaffolding to rapidly generate circumferentially aligned tubular constructs of human aortic smooth muscles cells with contractile gene expression for use as tissue engineered blood vessel media. Smooth muscle cells cultured on micropatterned and N-isopropylacrylamide-grafted (pNIPAm) polydimethylsiloxane (PDMS), a small portion of which was covered by aligned electrospun scaffolding, resulted in a single sheet of unidirectionally aligned cells. Upon cooling to room temperature, the scaffold, its adherent cells, and the remaining cell sheet detached and were collected on a mandrel to generating tubular constructs with circumferentially aligned smooth muscle cells which possess contractile gene expression and a single layer of electrospun scaffold as an analogue to a small diameter blood vessel's internal elastic lamina (IEL). This method improves cell sheet handling, results in rapid circumferential alignment of smooth muscle cells which immediately express contractile genes, and introduction of an analogue to small diameter blood vessel IEL. PMID:24411678

Rayatpisheh, Shahrzad; Heath, Daniel E; Shakouri, Amir; Rujitanaroj, Pim-On; Chew, Sing Yian; Chan-Park, Mary B

2014-03-01

160

Hybrid concept on the mechanical test method of small caliber blood vessel.  

PubMed

A mechanical test on small caliber blood vessel is difficult because the strength is very low and the dimension is very small. In the present paper a multifunctional axial test apparatus design is proposed. This has the characteristics such that the load cell and the environmental container for the specimen are built up in terms of cassette, respectively, and thus both are easy to equip and take off, that is, easy to replace. Also, the test methodology by internal pressure for small caliber blood vessels has been proposed. By using both of these methodologies, the characteristics of the mechanical behavior of small caliber blood vessels, such as compliance, stress relaxation, and viscoelastic property have been clarified. An attempt has been made on the application of this method to a clinical case. PMID:8205059

Yokobori, A T; Ohkuma, T; Yoshinari, H; Ichiki, M; Ohuchi, H; Yokobori, T

1993-01-01

161

ER71 acts downstream of BMP, Notch and Wnt signaling in blood and vessel progenitor specification  

PubMed Central

Summary FLK1 expressing (FLK1+) mesoderm generates blood and vessels. Here, we show that combined BMP, Notch and Wnt signaling is necessary for efficient FLK1+ mesoderm formation from embryonic stem (ES) cells. Inhibition of BMP, Notch and Wnt signaling pathways greatly decreased the generation of FLK1+ mesoderm and expression of the Ets transcription factor Er71. Enforced expression of ER71 in ES cells resulted in a robust induction of FLK1+ mesoderm, rescued the generation of FLK1+ mesoderm when blocked by BMP, Notch and Wnt inhibition, and enhanced hematopoietic and endothelial cell generation. Er71 deficient mice had greatly reduced FLK1 expression, died early in gestation and displayed severe blood and vessel defects that are highly reminiscent of the Flk1 null mouse phenotype. Collectively, we provide compelling evidence that ER71 functions downstream of BMP, Notch and Wnt signals and regulates FLK1+ mesoderm, blood and vessel development. PMID:18462699

Lee, Dongjun; Park, Changwon; Lee, Ho; Lugus, Jesse J.; Kim, Seok Hyung; Arentson, Elizabeth; Chung, Yun Shin; Gomez, Gustavo; Kyba, Michael; Lin, Shuo; Janknecht, Ralf; Lim, Dae-Sik; Choi, Kyunghee

2009-01-01

162

Vessel Labeling in Combined Confocal Scanning Laser Ophthalmoscopy and Optical Coherence Tomography Images: Criteria for Blood Vessel Discrimination  

PubMed Central

Introduction The diagnostic potential of optical coherence tomography (OCT) in neurological diseases is intensively discussed. Besides the sectional view of the retina, modern OCT scanners produce a simultaneous top-view confocal scanning laser ophthalmoscopy (cSLO) image including the option to evaluate retinal vessels. A correct discrimination between arteries and veins (labeling) is vital for detecting vascular differences between healthy subjects and patients. Up to now, criteria for labeling (cSLO) images generated by OCT scanners do not exist. Objective This study reviewed labeling criteria originally developed for color fundus photography (CFP) images. Methods The criteria were modified to reflect the cSLO technique, followed by development of a protocol for labeling blood vessels. These criteria were based on main aspects such as central light reflex, brightness, and vessel thickness, as well as on some additional criteria such as vascular crossing patterns and the context of the vessel tree. Results and Conclusion They demonstrated excellent inter-rater agreement and validity, which seems to indicate that labeling of images might no longer require more than one rater. This algorithm extends the diagnostic possibilities offered by OCT investigations. PMID:25203135

Motte, Jeremias; Alten, Florian; Ewering, Carina; Osada, Nani; Kadas, Ella M.; Brandt, Alexander U.; Oberwahrenbrock, Timm; Clemens, Christoph R.; Eter, Nicole; Paul, Friedemann; Marziniak, Martin

2014-01-01

163

MD Anderson study finds blood vessel cells coax colorectal cancer cells into more dangerous state  

Cancer.gov

Blood vessels that supply oxygen and nutrients to tumors can also deliver something else -- a signal that strengthens nearby cancer cells, making them more resistant to chemotherapy, more likely to spread to other organs and more lethal, scientists at The University of Texas MD Anderson Cancer Center report online in Cancer Cell. Working in human colorectal cancer cell lines and tumor samples, as well as mouse models, the researchers found that endothelial cells, which line the inside of blood vessels, can trigger changes in cancer cells without even coming into direct contact with them.

164

Thermal Reactions of Blood Vessels in Vascular Stroke and Heatstroke  

Microsoft Academic Search

Research on the pathophysiology and treatment of brain damage with special focus on thermal vascular responses is the subject of this minireview. Interruption of cerebral blood supply by vascular obstruction, temporary cardiac arrest or hyperthermia causes a sudden attack of vascular stroke or heatstroke with serious consequences. It may not induce immediate cell death, but can precipitate a complex biochemical

Olav Thulesius

2006-01-01

165

Evaluation of side effects of radiofrequency capacitive hyperthermia with magnetite on the blood vessel walls of tumor metastatic lesion surrounding the abdominal large vessels: an agar phantom study  

PubMed Central

Background Magnetite used in an 8-MHz radiofrequency (RF) capacitive heating device can increase the temperature of a specific site up to 45C. When treating a metastatic lesion around large abdominal vessels via hyperthermia with magnetite, heating-induced adverse effects on these vessels need to be considered. Therefore, this study examined hyperthermia-induced damage to blood vessel walls in vitro. Methods A large agar phantom with a circulatory system consisting of a swine artery and vein connected to a peristaltic pump was prepared. The blood vessels were placed on the magnetite-containing agar piece. Heating was continued for 30min at 45C. After heating, a histological study for injury to the blood vessels was performed. Results The inner membrane temperature did not reach 45C due to the cooling effect of the blood flow. In the heated vessels, vascular wall collagen degenerated and smooth muscle cells were narrowed; however, no serious changes were noted in the vascular endothelial cells or vascular wall elastic fibers. The heated vessel wall was not severely damaged; this was attributed to cooling by the blood flow. Conclusions Our findings indicate that RF capacitive heating therapy with magnetite may be used for metastatic lesions without injuring the surrounding large abdominal vessels. PMID:25114787

2014-01-01

166

Quantification of Blood Vessel Tortuosity and its Impact on Fenestrated Aortic Stent Grafts Research project will be undertaken at Toronto General Hospital under the supervision of Dr. Leonard  

E-print Network

Quantification of Blood Vessel Tortuosity and its Impact on Fenestrated Aortic Stent Grafts of fenestrated aortic stent grafts. Tortuosity is a measure of the deviation of a blood vessel from a straight line path. With age and disease, blood vessels tend to become more tortuous due to vessel lengthening

167

Automated artery-venous classification of retinal blood vessels based on structural mapping method  

NASA Astrophysics Data System (ADS)

Retinal blood vessels show morphologic modifications in response to various retinopathies. However, the specific responses exhibited by arteries and veins may provide a precise diagnostic information, i.e., a diabetic retinopathy may be detected more accurately with the venous dilatation instead of average vessel dilatation. In order to analyze the vessel type specific morphologic modifications, the classification of a vessel network into arteries and veins is required. We previously described a method for identification and separation of retinal vessel trees; i.e. structural mapping. Therefore, we propose the artery-venous classification based on structural mapping and identification of color properties prominent to the vessel types. The mean and standard deviation of each of green channel intensity and hue channel intensity are analyzed in a region of interest around each centerline pixel of a vessel. Using the vector of color properties extracted from each centerline pixel, it is classified into one of the two clusters (artery and vein), obtained by the fuzzy-C-means clustering. According to the proportion of clustered centerline pixels in a particular vessel, and utilizing the artery-venous crossing property of retinal vessels, each vessel is assigned a label of an artery or a vein. The classification results are compared with the manually annotated ground truth (gold standard). We applied the proposed method to a dataset of 15 retinal color fundus images resulting in an accuracy of 88.28% correctly classified vessel pixels. The automated classification results match well with the gold standard suggesting its potential in artery-venous classification and the respective morphology analysis.

Joshi, Vinayak S.; Garvin, Mona K.; Reinhardt, Joseph M.; Abramoff, Michael D.

2012-03-01

168

Peristaltic Pumping of Blood Through Small Vessels of Varying Cross-section  

E-print Network

The paper is devoted to a study of the peristaltic motion of blood in the micro-circulatory system. The vessel is considered to be of varying cross-section. The progressive peristaltic waves are taken to be of sinusoidal nature. Blood is considered to be a Herschel-Bulkley fluid. Of particular concern here is to investigate the effects of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, streamline pattern and wall shear stress. On the basis of the derived analytical expression, extensive numerical calculations have been made. The study reveals that velocity of blood and wall shear stress are appreciably affected due to the non-uniform geometry of blood vessels. They are also highly sensitive to the magnitude of the amplitude ratio and the value of the fluid index.

J. C. Misra; S. Maiti

2012-01-30

169

[The blood vessels of the mesonephros of domestic cattle (Bos taurus), a corrosion cast study].  

PubMed

The blood vessels of the bovine mesonephros - a corrosion cast study Using scanning electron microscopy plastoid corrosion cast specimens of the mesonephros of 30-45-day-old bovine foetuses were investigated. The studies showed that the blood vessels of the mesonephros are organized in two separate networks similar to these of the teleosts and amphibians. The glomerula mesonephrica originate from the aorta implying that they belong to the high pressure system. The tubuli mesonephrici are surrounded by a filamentous independent capillary network which is shown for the first time in these studies. This capillary network originates from the caudal cardinal veins and represents a mesonephric portal system with a relatively low blood pressure. The blood from the two capillary networks diverts into terminal veins and into the subcardinal veins. The questions of haemodynamics in the mesonephros are discussed. PMID:15239810

Vollmerhaus, B; Reese, S; Roos, H

2004-08-01

170

Occlusion of Small Vessels by Malaria-Infected Red Blood Cells  

NASA Astrophysics Data System (ADS)

We use dissipative particle dynamics (DPD) method to study malaria-infected red blood cells (i-RBC). We have developed a multi-scale model to describe both static and dynamic properties of RBCs. With this model, we study the adhesive interaction between RBCs as well as the interaction between the Plasmodium falciparum (Pf)-parasitized cells and a vessel wall coated with purified ICAM-1. In this talk, we will discuss the effect of the Pf-parasitized malaria cell on the flow resistance of the blood flow at different parasetimia levels. The blood flow in malaria disease shows high flow resistance as compared with the healthy case due to both the stiffening of the i-RBCs (up to ten times) as well as the adhesion dynamics. For certain sizes of of small vessels, the malaria-infected cells can even lead to occlusion of the blood flow, in agreement with recent experiments.

Lei, Huan; Fedosov, Dmitry; Caswell, Bruce; Karniadakis, George

2010-11-01

171

Role of tissue factor in embryonic blood vessel development  

Microsoft Academic Search

TISSUE factor, a member of the cytokine-receptor superfamily and high-affinity receptor and cofactor for plasma factor Vll\\/VIIa (ref. 1), is the primary cellular initiator of blood coagulation. It is involved in thrombosis and inflammation associated with sepsis, atherosclerosis and cancer2, and can participate in other cellular processes including intracellular signalling3, metastasis4, tumour-associated angiogenesis5, and embryogenesis6. Here we report that inactivation

Peter Carmeliet; Nigel Mackman; Lieve Moons; Thomas Luther; Pierre Gressens; Lise van Vlaenderen; Hilde Demunck; Michael Kasper; Georg Breier; Philippe Evrard; Martin Mller; Werner Risau; Thomas Edgington; Dsir Collen

1996-01-01

172

Blood Vessels as a Source of Progenitor Cells in Human Embryonic and Adult Life  

Microsoft Academic Search

Recent experimental results in culture and in vivo are summarized that show the existence of developmental relationships between cells that build up blood vessel walls and\\u000a some previously unrelated tissues and organs. It was formerly demonstrated, in lower vertebrates as well as mammals, including\\u000a humans, that discrete subsets of blood-forming endothelial cells play a key role in the emergence of

Mihaela Crisan; Bo Zheng; Elias T. Zambidis; Solomon Yap; Manuela Tavian; Bin Sun; Jean-Paul Giacobino; Louis Casteilla; Johnny Huard; Bruno Pault

173

Polarized Monte Carlo simulation of blood vessel structure in colon tissue  

NASA Astrophysics Data System (ADS)

A modified polarized Monte Carlo code is developed that allows heterogeneous structure to be modeled. The code is validated with existent polarized Monte Carlo code. Heterogeneous structure simulating colon tissue is simulated to understand the difference between simulations of homogeneous vs heterogeneous tissue structure. Reflectance measurements from simulations containing increased blood vessel size and increased blood volume fraction, both markers for potential cancerous tissue, are studied in order to better interpret reflectance measurement from diagnostic probes.

Yip, Wendy; Gomes, Andrew; Backman, Vadim; Sahakian, Alan

2012-03-01

174

Feasibility of Using the Marginal Blood Vessels as Reference Landmarks for CT Colonography  

PubMed Central

OBJECTIVE The purpose of this study was to show the spatial relationship of the colonic marginal blood vessels and the teniae coli on CT colonography (CTC) and the use of the marginal blood vessels for supine-prone registration of polyps and for determination of proper connectivity of collapsed colonic segments. MATERIALS AND METHODS We manually labeled the marginal blood vessels on 15 CTC examinations. Colon segmentation, centerline extraction, teniae detection, and teniae identification were automatically performed. For assessment of their spatial relationships, the distances from the marginal blood vessels to the three teniae coli and to the colon were measured. Student t tests (paired, two-tailed) were performed to evaluate the differences among these distances. To evaluate the reliability of the marginal vessels as reference points for polyp correlation, we analyzed 20 polyps from 20 additional patients who underwent supine and prone CTC. The average difference of the circumferential polyp position on the supine and prone scans was computed. Student t tests (paired, two-tailed) were performed to evaluate the supine-prone differences of the distance. We performed a study on 10 CTC studies from 10 patients with collapsed colonic segments by manually tracing the marginal blood vessels near the collapsed regions to resolve the ambiguity of the colon path. RESULTS The average distances ( SD) from the marginal blood vessels to the tenia mesocolica, tenia omentalis, and tenia libera were 20.1 3.1 mm (95% CI, 18.521.6 mm), 39.5 4.8 mm (37.142.0 mm), and 36.9 4.2 mm (34.839.1 mm), respectively. Pairwise comparison showed that these distances to the tenia libera and tenia omentalis were significantly different from the distance to the tenia mesocolica (p < 0.001). The average distance from the marginal blood vessels to the colon wall was 15.3 2.0 mm (14.216.3 mm). For polyp localization, the average difference of the circumferential polyp position on the supine and prone scans was 9.6 9.4 mm (5.513.7 mm) (p = 0.15) and expressed as a percentage of the colon circumference was 3.1% 2.0% (2.34.0%) (p = 0.83). We were able to trace the marginal blood vessels for 10 collapsed colonic segments and determine the paths of the colon in these regions. CONCLUSION The marginal blood vessels run parallel to the colon in proximity to the tenia mesocolica and enable accurate supine-prone registration of polyps and localization of the colon path in areas of collapse. Thus, the marginal blood vessels may be used as reference landmarks complementary to the colon centerline and teniae coli. PMID:24370165

Wei, Zhuoshi; Yao, Jianhua; Wang, Shijun; Liu, Jiamin; Dwyer, Andrew J.; Pickhardt, Perry J.; Nowinski, Wieslaw L.; Summers, Ronald M.

2015-01-01

175

A New Seeded Region Growing Technique for Retinal Blood Vessels Extraction  

PubMed Central

Distribution of retinal blood vessels (RBVs) in retinal images has an important role in the prevention, diagnosis, monitoring and treatment of diseases, such as diabetes, high blood pressure, or heart disease. Therefore, detection of the exact location of RBVs is very important for Ophthalmologists. One of the frequently used techniques for extraction of these vessels is region growing-based Segmentation. In this paper, we propose a new region growing (RG) technique for RBVs extraction, called cellular automata-based segmentation. RG techniques often require manually seed point selection, that is, human intervention. However, due to the complex structure of vessels in retinal images, manual tracking of them is very difficult. Therefore, to make our proposed technique full automatic, we use an automatic seed point selection method. The proposed RG technique was tested on Digital Retinal Images for Vessel Extraction database for three different initial seed sets and evaluated against the manual segmentation of retinal images available at this database. Three quantitative criteria including accuracy, true positive rate and false positive rate, were considered to evaluate this method. The visual scrutiny of the segmentation results and the quantitative criteria show that, using cellular automata for extracting the blood vessels is promising. However, the important point at here is that the correct initial seeds have an effective role on the final results of segmentation. PMID:25298931

Sajadi, Atefeh Sadat; Sabzpoushan, Seyed Hojat

2014-01-01

176

Normalization of tumour blood vessels improves the delivery of nanomedicines in a size-dependent manner  

NASA Astrophysics Data System (ADS)

The blood vessels of cancerous tumours are leaky and poorly organized. This can increase the interstitial fluid pressure inside tumours and reduce blood supply to them, which impairs drug delivery. Anti-angiogenic therapies--which `normalize' the abnormal blood vessels in tumours by making them less leaky--have been shown to improve the delivery and effectiveness of chemotherapeutics with low molecular weights, but it remains unclear whether normalizing tumour vessels can improve the delivery of nanomedicines. Here, we show that repairing the abnormal vessels in mammary tumours, by blocking vascular endothelial growth factor receptor-2, improves the delivery of smaller nanoparticles (diameter, 12 nm) while hindering the delivery of larger nanoparticles (diameter, 125 nm). Using a mathematical model, we show that reducing the sizes of pores in the walls of vessels through normalization decreases the interstitial fluid pressure in tumours, thus allowing small nanoparticles to enter them more rapidly. However, increased steric and hydrodynamic hindrances, also associated with smaller pores, make it more difficult for large nanoparticles to enter tumours. Our results further suggest that smaller (~12 nm) nanomedicines are ideal for cancer therapy due to their superior tumour penetration.

Chauhan, Vikash P.; Stylianopoulos, Triantafyllos; Martin, John D.; Popovi?, Zoran; Chen, Ou; Kamoun, Walid S.; Bawendi, Moungi G.; Fukumura, Dai; Jain, Rakesh K.

2012-06-01

177

The role of pericytes in blood-vessel formation and maintenance1  

PubMed Central

Blood vessels are composed of two interacting cell types. Endothelial cells form the inner lining of the vessel wall, and perivascular cellsreferred to as pericytes, vascular smooth muscle cells or mural cellsenvelop the surface of the vascular tube. Over the last decades, studies of blood vessels have concentrated mainly on the endothelial cell component, especially when the first angiogenic factors were discovered, while the interest in pericytes has lagged behind. Pericytes are, however, functionally significant; when vessels lose pericytes, they become hemorrhagic and hyperdilated, which leads to conditions such as edema, diabetic retinopathy, and even embryonic lethality. Recently, pericytes have gained new attention as functional and critical contributors to tumor angiogenesis and therefore as potential new targets for antiangiogenic therapies. Pericytes are complex. Their ontogeny is not completely understood, and they perform various functions throughout the body. This review article describes the current knowledge about the nature of pericytes and their functions during vessel growth, vessel maintenance, and pathological angiogenesis. PMID:16212810

Bergers, Gabriele; Song, Steven

2005-01-01

178

A Microstructurally Motivated Model of the Mechanical Behavior of Tissue Engineered Blood Vessels  

PubMed Central

Mechanical models have potential to guide the development and use of engineered blood vessels as well as other engineered tissues. This paper presents a microstructurally motivated, pseudoelastic, mechanical model of the biaxial mechanics of engineered vessels in the physiologic pressure range. The model incorporates experimentally measured densities and alignments of engineered collagen. Specifically, these microstructural and associated mechanical inputs were measured directly from engineered blood vessels that were cultured over periods of 57.5 weeks. To the best of our knowledge, this is the first successful application of either a phenomenological or a microstructurally motivated mechanical model to engineered vascular tissues. Model development revealed the need to use novel theoretical configurations to describe the strain history of engineered vessels. The constitutive equations developed herein suggested that collagen remodeled between 5 and 7.5 weeks during a 7.5-week culture period. This remodeling led to strain energies for collagen that differed with alignment, which likely resulted from undulations that varied with alignment. Finally, biaxial data emphasized that axial extensions increase stresses in engineered vessels in the physiologic pressure range, thereby providing a guideline for surgical use: engineered vessels should be implanted at appropriate axial extension to minimize adverse stress responses. PMID:18720007

Dahl, Shannon L. M.; Vaughn, Megann E.; Hu, Jin-Jia; Driessen, Niels J. B.; Baaijens, Frank P. T.; Humphrey, Jay D.; Niklason, Laura E.

2008-01-01

179

An important role of blood and lymphatic vessels in inflammation and allergy.  

PubMed

Angiogenesis and lymphangiogenesis, the growth of new vessels from preexisting ones, have received increasing interest due to their role in tumor growth and metastatic spread. However, vascular remodeling, associated with vascular hyperpermeability, is also a key feature of many chronic inflammatory diseases including asthma, atopic dermatitis, psoriasis, and rheumatoid arthritis. The major drivers of angiogenesis and lymphangiogenesis are vascular endothelial growth factor- (VEGF-)A and VEGF-C, activating specific VEGF receptors on the lymphatic and blood vascular endothelium. Recent experimental studies found potent anti-inflammatory responses after targeted inhibition of activated blood vessels in models of chronic inflammatory diseases. Importantly, our recent results indicate that specific activation of lymphatic vessels reduces both acute and chronic skin inflammation. Thus, antiangiogenic and prolymphangiogenic therapies might represent a new approach to treat chronic inflammatory disorders, including those due to chronic allergic inflammation. PMID:23431319

Zgraggen, Silvana; Ochsenbein, Alexandra M; Detmar, Michael

2013-01-01

180

Adrenergic innervation of blood vessels in rat tibial nerve during Wallerian degeneration  

Microsoft Academic Search

Adrenergic innervation of blood vessels in rat tibial nerve during Wallerian degeneration was examined, using the formaldehyde-induced histo-fluorescence method. The left sciatic nerve was transected at the level of the sciatic notch, whereas the right sciatic nerve was left intact and used as control. At 1, 3, 7, 14, 42, 56 or 84 days after transection, the tibial nerves of

J. Koistinaho; K. C. Wadhwani; C. H. Latker; A. Balbo; S. I. Rapoport

1990-01-01

181

A meshless rheological model for blood-vessel interaction in endovascular simulation.  

PubMed

A meshless rheological model is proposed for medical simulation of vascular procedures. Due to the complexity of rheologic models involved in endovascular simulations, delivering a high level of interactivity with realistic biomechanical feedback is still a challenge. In this paper, we propose a particle-based rheologic modeling method for virtual catheterisation training applications. The effect of blood rheology has been simulated through a smoothed particle hydrodynamics (SPH) formulation of non-Newtonian flow. By modeling vessel wall structure as virtual particles, a pure Lagrange particle formulation for fluid-structure interaction (FSI) is purposed for modeling the blood-vessel interaction. We further propose a flow-related thrombus (clot) formation-dissolution model based on our fluid-solid interaction framework. A physics processing API (PhysX) friendly implementation is proposed for incorporating the rheological properties of blood and vessel wall into our framework. Results have demonstrated the feasibility of employing our proposed meshfree framework in simulating blood-vessel interaction and clotting behaviors which are essential to endovascular simulations. Having benefited from the elegant formulation of Lagrangian particle interaction, interactive framerates of the simulation can be maintained under hardware-acceleration. PMID:20868705

Chui, Yim-Pan; Heng, Pheng-Ann

2010-12-01

182

Designing A Pattern Stabilization Method Using Scleral Blood Vessels For Laser Eye Surgery  

E-print Network

Designing A Pattern Stabilization Method Using Scleral Blood Vessels For Laser Eye Surgery Aydin,abc}@cs.hacettepe.edu.tr, hbcakmak@gmail.com Abstract-- In laser eye surgery, the accuracy of operation depends on coherent eye tracking and registration techniques. Main approach used in image processing based eye trackers

Erdem, Erkut

183

Enhanced Bonding Strength of Hydrophobically Modified Gelatin Films on Wet Blood Vessels  

PubMed Central

The bonding behavior between hydrophobically modified alkaline-treated gelatin (hm-AlGltn) films and porcine blood vessels was evaluated under wet conditions. Hexanoyl (Hx: C6), decanoyl (Dec: C10), and stearyl (Ste: C18) chlorides were introduced into the amino groups of AlGltn to obtain HxAlGltn, DecAlGltn, and SteAlGltn, respectively, with various modification percentages. The hm-AlGltn was fabricated into films and thermally crosslinked to obtain water-insoluble films (t-hm-AlGltn). The 42% modified t-HxAlGltn (t-42HxAlGltn) possessed higher wettability than the 38% modified t-DecAlGltn (t-38DecAlGltn) and the 44% modified t-SteAlGltn (t-44SteAlGltn) films, and the t-42HxAlGltn film showed a high bonding strength with the blood vessel compared with all the hm-AlGltn films. Histological observations indicated that t-42HxAlGltn and t-38DecAlGltn remained on the blood vessel even after the bonding strength measurements. From cell culture experiments, the t-42HxAlGltn films showed significant cell adhesion compared to other films. These findings indicate that the Hx group easily interpenetrated the surface of blood vessels and effectively enhanced the bonding strength between the films and the tissue. PMID:24481063

Yoshizawa, Keiko; Taguchi, Tetsushi

2014-01-01

184

Mayo Clinic-led study unravels biological pathway that controls the leakiness of blood vessels  

Cancer.gov

A research team led by scientists at Mayo Clinic in Florida have decoded the entire pathway that regulates leakiness of blood vessels, a condition that promotes a wide number of disorders, such as heart disease, cancer growth and spread, inflammation and respiratory distress.

185

Mass General study finds normalizing tumor blood vessels improves delivery of only the smallest nanomedicines  

Cancer.gov

Combining two strategies designed to improve the results of cancer treatment antiangiogenesis drugs and nanomedicines may only be successful if the smallest nanomedicines are used. A new study from Massachusetts General Hospital researchers, appearing in Nature Nanotechnology, finds that normalizing blood vessels within tumors, which improves the delivery of standard chemotherapy drugs, can block the delivery of larger nanotherapy molecules.

186

Numerical study of the feasibility of scanning hematoma and blood vessels in the human brain  

NASA Astrophysics Data System (ADS)

We study theoretically the problem of sensitivity of frequency modulated reflectance to the inclusion of either a hematoma, modeled as a large slab, or a blood vessel, modeled as a straight tube, in semi-infinite human tissue systems. We use two different numerical techniques: (1) numerical integration of three-dimensional diffusion equation; and (2) Monte Carlo simulations with a biasing technique. We find that inclusion of a hematoma slab or a blood vessel cylinder gives rise to significant change in both the phase and modulation as compared to a homogeneous medium. The reflected signals from these two situations are also significantly different which may allow differentiation between the two objects. In the particular case of imbedded cylindrical blood vessel we find that up to a depth of z equals 25 mm it is possible to use the phase shift or modulation change of reflected photon flux at different locations on the sample surface to determine the direction, size, and depth of the embedded blood vessel, provided phase change sensitivity of 0.1 deg or modulation change sensitivity 0.01 are available.

Feng, Shechao C.; Zhao, H. L.; Zeng, Fanan

1995-01-01

187

Angiotensin inhibition enhances drug delivery and potentiates chemotherapy by decompressing tumour blood vessels  

PubMed Central

Cancer and stromal cells actively exert physical forces (solid stress) to compress tumour blood vessels, thus reducing vascular perfusion. Tumour interstitial matrix also contributes to solid stress, with hyaluronan implicated as the primary matrix molecule responsible for vessel compression because of its swelling behaviour. Here we show, unexpectedly, that hyaluronan compresses vessels only in collagen-rich tumours, suggesting that collagen and hyaluronan together are critical targets for decompressing tumour vessels. We demonstrate that the angiotensin inhibitor losartan reduces stromal collagen and hyaluronan production, associated with decreased expression of profibrotic signals TGF-?1, CCN2 and ET-1, downstream of angiotensin-II-receptor-1 inhibition. Consequently, losartan reduces solid stress in tumours resulting in increased vascular perfusion. Through this physical mechanism, losartan improves drug and oxygen delivery to tumours, thereby potentiating chemotherapy and reducing hypoxia in breast and pancreatic cancer models. Thus, angiotensin inhibitors inexpensive drugs with decades of safe use could be rapidly repurposed as cancer therapeutics. PMID:24084631

Chauhan, Vikash P.; Martin, John D.; Liu, Hao; Lacorre, Delphine A.; Jain, Saloni R.; Kozin, Sergey V.; Stylianopoulos, Triantafyllos; Mousa, Ahmed S.; Han, Xiaoxing; Adstamongkonkul, Pichet; Popovi?, Zoran; Huang, Peigen; Bawendi, Moungi G.; Boucher, Yves; Jain, Rakesh K.

2013-01-01

188

Non-Newtonian characteristics of peristaltic flow of blood in micro-vessels  

NASA Astrophysics Data System (ADS)

Of concern in the paper is a generalized theoretical study of the non-Newtonian characteristics of peristaltic flow of blood through micro-vessels, e.g. arterioles. The vessel is considered to be of variable cross-section and blood to be a Herschel-Bulkley type of fluid. The progressive wave front of the peristaltic flow is supposed sinusoidal/straight section dominated (SSD) (expansion/contraction type); Reynolds number is considered to be small with reference to blood flow in the micro-circulatory system. The equations that govern the non-Newtonian peristaltic flow of blood are considered to be non-linear. The objective of the study has been to examine the effect of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, wall shear stress, streamline pattern and trapping. It is observed that the numerical estimates for the aforesaid quantities in the case of peristaltic transport of blood in a channel are much different from those for flow in an axisymmetric vessel of circular cross-section. The study further shows that peristaltic pumping, flow velocity and wall shear stress are significantly altered due to the non-uniformity of the cross-sectional radius of blood vessels of the micro-circulatory system. Moreover, the magnitude of the amplitude ratio and the value of the fluid index are important parameters that affect the flow behaviour. Novel features of SSD wave propagation that affect the flow behaviour of blood have also been discussed.

Maiti, S.; Misra, J. C.

2013-08-01

189

The Rheology of Blood Flow in a Branched Arterial System.  

PubMed

Blood flow rheology is a complex phenomenon. Presently there is no universally agreed upon model to represent the viscous property of blood. However, under the general classification of non-Newtonian models that simulate blood behavior to different degrees of accuracy, there are many variants. The power law, Casson and Carreau models are popular non-Newtonian models and affect hemodynamics quantities under many conditions. In this study, the finite volume method is used to investigate hemodynamics predictions of each of the models. To implement the finite volume method, the computational fluid dynamics software Fluent 6.1 is used. In this numerical study the different hemorheological models are found to predict different results of hemodynamics variables which are known to impact the genesis of atherosclerosis and formation of thrombosis. The axial velocity magnitude percentage difference of up to 2 % and radial velocity difference up to 90 % is found at different sections of the T-junction geometry. The size of flow recirculation zones and their associated separation and reattachment point's locations differ for each model. The wall shear stress also experiences up to 12 % shift in the main tube. A velocity magnitude distribution of the grid cells shows that the Newtonian model is close dynamically to the Casson model while the power law model resembles the Carreau model. ZUSAMMENFASSUNG: Die Rheologie von Blutstrmungen ist ein komplexes Phnomen. Gegenwrtig existiert kein allgemein akzeptiertes Modell, um die viskosen Eigenschaften von Blut wiederzugeben. Jedoch gibt es mehrere Varianten unter der allgemeinen Klassifikation von nicht-Newtonschen Modellen, die das Verhalten von Blut mit unterschiedlicher Genauigkeit simulieren. Die Potenzgesetz-, Casson und Carreau-Modelle sind beliebte nicht-New-tonsche Modelle und beeinflussen die hmodynamischen Eigenschaften in vielen Situationen. In dieser Studie wurde die finite Volumenmethode angewandt, um die hmodynamischen Vorhersagen dieser Modelle zu untersuchen. Um die finite Volumenmethode zu implementieren, wurde die Fluiddynamiksoftware Fluent 6.1 verwendet. In dieser numerischen Studie wurde gefunden, dass die unterschiedlichen hmorheologischen Modelle unterschiedliche Resultate fr die hmodynamischen Grssen vorhersagen, von denen bekannt ist, dass sie die Entstehung von Arteriosklerose und die Bildung von Thrombose beeinflussen. Es wurde gefunden, dass die relative Differenz der axialen Geschwindigkeit bis zu 2% und die der radialen Geschwindigkeit bis zu 90% in unterschiedlichen Abschnitten der T-Verbindung betrgt. Die Grsse der Strmungszirkulationszonen und ihrer dazugehrigen Trennungs- und Vereinigungspunkte differieren fr jedes Modell. Die Scherspannung an der Wand erfhrt ebenfalls eine Verschiebung im Hauptrohr von bis zu 12%. Der Verlauf der Geschwindigkeit auf den Gitterzellen zeigt, dass das Newtonsche Modell mit Bezug auf die Dynamik dem Casson-Modell nahe ist, whrend das Potenzgesetzmodell dem Carreau-Modell hnlich ist. R#ENTITYSTARTX000E9;SUM#ENTITYSTARTX000E9;: La rhologie de l'coulement sanguin est un phnomne complexe. Prsentement, il n'y a pas de consensus universel sur le modle qui reprsente la proprit visqueuse du sang. Cependant, parmi la classification gnrale des modles non-Newtoniens qui simulent le comportement du sang avec diffrents degrs de prcision, il y a plusieurs diffrences. Les lois de puissance, les modles de Casson et Carreau sont des modles non-Newtoniens populaires et ont un effet sur les quantits hmodynamiques sous plusieurs conditions. Dans cette tude, la mthode de volume fini est utilise pour explorer les prdictions hmodynamiques de chacun de ces modles. Pour implmenter la mthode de volume fini, le logiciel de calcul de dynamique des fluides Fluent 6.1 a t utilis. Dans cette tude numrique, les diffrents modles hmorhologiques tendent prdire des rsultats diffrents pour les variables hmodynamiques qui sont reconnues comme aya

Shibeshi, Shewaferaw S; Collins, William E

2005-01-01

190

The Rheology of Blood Flow in a Branched Arterial System  

PubMed Central

Blood flow rheology is a complex phenomenon. Presently there is no universally agreed upon model to represent the viscous property of blood. However, under the general classification of non-Newtonian models that simulate blood behavior to different degrees of accuracy, there are many variants. The power law, Casson and Carreau models are popular non-Newtonian models and affect hemodynamics quantities under many conditions. In this study, the finite volume method is used to investigate hemodynamics predictions of each of the models. To implement the finite volume method, the computational fluid dynamics software Fluent 6.1 is used. In this numerical study the different hemorheological models are found to predict different results of hemodynamics variables which are known to impact the genesis of atherosclerosis and formation of thrombosis. The axial velocity magnitude percentage difference of up to 2 % and radial velocity difference up to 90 % is found at different sections of the T-junction geometry. The size of flow recirculation zones and their associated separation and reattachment point's locations differ for each model. The wall shear stress also experiences up to 12 % shift in the main tube. A velocity magnitude distribution of the grid cells shows that the Newtonian model is close dynamically to the Casson model while the power law model resembles the Carreau model. Zusammenfassung Die Rheologie von Blutstrmungen ist ein komplexes Phnomen. Gegenwrtig existiert kein allgemein akzeptiertes Modell, um die viskosen Eigenschaften von Blut wiederzugeben. Jedoch gibt es mehrere Varianten unter der allgemeinen Klassifikation von nicht-Newtonschen Modellen, die das Verhalten von Blut mit unterschiedlicher Genauigkeit simulieren. Die Potenzgesetz-, Casson und Carreau-Modelle sind beliebte nicht-New-tonsche Modelle und beeinflussen die hmodynamischen Eigenschaften in vielen Situationen. In dieser Studie wurde die finite Volumenmethode angewandt, um die hmodynamischen Vorhersagen dieser Modelle zu untersuchen. Um die finite Volumenmethode zu implementieren, wurde die Fluiddynamiksoftware Fluent 6.1 verwendet. In dieser numerischen Studie wurde gefunden, dass die unterschiedlichen hmorheologischen Modelle unterschiedliche Resultate fr die hmodynamischen Gren vorhersagen, von denen bekannt ist, dass sie die Entstehung von Arteriosklerose und die Bildung von Thrombose beeinflussen. Es wurde gefunden, dass die relative Differenz der axialen Geschwindigkeit bis zu 2% und die der radialen Geschwindigkeit bis zu 90% in unterschiedlichen Abschnitten der T-Verbindung betrgt. Die Gre der Strmungszirkulationszonen und ihrer dazugehrigen Trennungs- und Vereinigungspunkte differieren fr jedes Modell. Die Scherspannung an der Wand erfhrt ebenfalls eine Verschiebung im Hauptrohr von bis zu 12%. Der Verlauf der Geschwindigkeit auf den Gitterzellen zeigt, dass das Newtonsche Modell mit Bezug auf die Dynamik dem Casson-Modell nahe ist, whrend das Potenzgesetzmodell dem Carreau-Modell hnlich ist. Rsum La rhologie de l'coulement sanguin est un phnomne complexe. Prsentement, il n'y a pas de consensus universel sur le modle qui reprsente la proprit visqueuse du sang. Cependant, parmi la classification gnrale des modles non-Newtoniens qui simulent le comportement du sang avec diffrents degrs de prcision, il y a plusieurs diffrences. Les lois de puissance, les modles de Casson et Carreau sont des modles non-Newtoniens populaires et ont un effet sur les quantits hmodynamiques sous plusieurs conditions. Dans cette tude, la mthode de volume fini est utilise pour explorer les prdictions hmodynamiques de chacun de ces modles. Pour implmenter la mthode de volume fini, le logiciel de calcul de dynamique des fluides Fluent 6.1 a t utilis. Dans cette &

Shibeshi, Shewaferaw S.; Collins, William E.

2006-01-01

191

Finite-sized gas bubble motion in a blood vessel: Non-Newtonian effects  

NASA Astrophysics Data System (ADS)

We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air bubble through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid modela cell-free layer and a non-Newtonian core together with the gas bubble. This problem is of interest to the field of rheology and for gas embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=?lUmaxd/?app , in the neighborhood of 0.2, 2, and 200 are investigated. Here, ?l is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and ?app is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of bubble occlusion is characterized by the ratio of bubble to vessel radius (aspect ratio), ? , in the range 0.9???1.05 . For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) bubble motion causes large temporal and spatial gradients of shear stress at the endothelial cell (EC) surface lining the blood vessel wall as the bubble approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ ? - ? +) imparted to the cell surface during bubble motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the rear of the bubble; (iv) computed magnitudes of shear stress gradients coupled with their sign reversals may correspond to levels that cause injury to the cell by membrane disruption through impulsive compression and stretching; and (v) for the vessel sizes and flow rates investigated, gravitational effects are negligible.

Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S.; Eckmann, David M.

2008-09-01

192

Finite-sized gas bubble motion in a blood vessel: Non-Newtonian effects  

PubMed Central

We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air bubble through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid modela cell-free layer and a non-Newtonian core together with the gas bubble. This problem is of interest to the field of rheology and for gas embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=?lUmaxd/?app, in the neighborhood of 0.2, 2, and 200 are investigated. Here, ?l is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and ?app is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of bubble occlusion is characterized by the ratio of bubble to vessel radius (aspect ratio), ?, in the range 0.9???1.05. For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) bubble motion causes large temporal and spatial gradients of shear stress at the endothelial cell (EC) surface lining the blood vessel wall as the bubble approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ ? ? ? +) imparted to the cell surface during bubble motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the rear of the bubble; (iv) computed magnitudes of shear stress gradients coupled with their sign reversals may correspond to levels that cause injury to the cell by membrane disruption through impulsive compression and stretching; and (v) for the vessel sizes and flow rates investigated, gravitational effects are negligible. PMID:18851139

Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S.; Eckmann, David M.

2009-01-01

193

Finite-sized gas bubble motion in a blood vessel: non-Newtonian effects.  

PubMed

We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air bubble through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid model--a cell-free layer and a non-Newtonian core together with the gas bubble. This problem is of interest to the field of rheology and for gas embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=rholUmaxdmicroapp , in the neighborhood of 0.2, 2, and 200 are investigated. Here, rhol is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and microapp is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of bubble occlusion is characterized by the ratio of bubble to vessel radius (aspect ratio), lambda , in the range 0.9< or =lambda< or =1.05 . For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) bubble motion causes large temporal and spatial gradients of shear stress at the "endothelial cell" (EC) surface lining the blood vessel wall as the bubble approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ --> - --> +) imparted to the cell surface during bubble motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the rear of the bubble; (iv) computed magnitudes of shear stress gradients coupled with their sign reversals may correspond to levels that cause injury to the cell by membrane disruption through impulsive compression and stretching; and (v) for the vessel sizes and flow rates investigated, gravitational effects are negligible. PMID:18851139

Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S; Eckmann, David M

2008-09-01

194

Scanning and transmission electron microscope study on the terminal blood vessels of the rat skin.  

PubMed

The microvasculature in the subepidermal layer of the rat foot was examined by scanning electron microscopy of corrosion casts and by transmission electron microscopy of serial ultrathin sections. Three-dimensional observation of the casts demonstrated that, in the walking pads (pressure areas) with a thick epidermis, terminal vessels formed tortuous capillary loops that penetrated vertically into well-developed dermal papillae. In other regions of the foot (non-pressure areas) with a thin epidermis, terminal vessels formed a horizontally arranged capillary network and each capillary of the network fitted into a shallow groove along the dermal epidermal boundary base. These differences in the pattern of vascular distribution might be of significance from the view point of the blood flow; in pressure areas, the vertically arranged, tortuous vessels might allow vertical mobility of the skin without injury to them and might keep the blood flow normal against the force of compression. In thin sections, however, capillaries of both the loops and networks were similar in spite of the differences in the vascular distribution and the architecture of the epidermal-dermal junction. Vessels located in close proximity to the epidermis exhibited endothelial fenestrations along their proximal margins. In vessels away from the epidermis, on the contrary, fenestrations were not apparent. Since endothelial fenestration is an anatomical property related to rapid material exchange, it may be concluded that the pattern of distribution and the fine structure of subepidermal capillaries adjusts to the metabolic needs of the epidermis. PMID:7240783

Imayama, S

1981-03-01

195

The impact of ischaemia-reperfusion on the blood vessel.  

PubMed

Ischaemia significantly affects the cellular homeostasis (sodium and calcium overload, intracellular acidosis, swelling, cytoskeleton injuries, mitochondrial hypercalcaemia and others). If reperfusion of an organ in ischaemia is essential for its viability and its functional recovery, the arrival of blood oxygen will cause a series of lesions; this is known as the phenomenon of ischaemia-reperfusion. Vasomotricity and the endothelial functions are significantly affected by it. Endothelium-dependent vasodilatation is more affected by ischaemia-reperfusion injuries than vasoconstriction and endothelial-independent vasodilatation. Reactive oxygen species and tumour necrosis factor-alpha seem to play a major role in this perturbation. Reperfusion also induces an important inflammatory response, characterized by a massive production of free radicals and by the activation of the complement and leucocyte neutrophils. A narrow interaction between activated endothelium and neutrophils will result in a significant concentration of neutrophils activated in the interstitium, where they release many oxygen radicals and many kinds of proteases, which destroy cells and extracellular matrix. This transfer of neutrophils from the intravascular bed to the intestitium involves several families of proteins such as selectins (P-selectin and L-selectin), integrines (intercellular adhesion molecule-1) and immunoglobulins (platelet-endothelial cell adhesion molecule-1). Last, oxidative stress, the production of cytokines and the secondary mitochondrial lesions that occur with reperfusion will induce apoptosis on the level of the parenchyma and the vascular structures. According to the stage of the vascular system considered (small arteries, capillaries or postcapillary veins), the repercussions of ischaemia-reperfusion are identical, but the clinical pictures differ. The proinflammatory state induced by reperfusion continues for several days and can affect the patient's prognosis. PMID:19412112

Gourdin, Maximilien J; Bree, Bernard; De Kock, Marc

2009-07-01

196

Generation of functionally competent and durable engineered blood vessels from human induced pluripotent stem cells  

PubMed Central

Efficient generation of competent vasculogenic cells is a critical challenge of human induced pluripotent stem (hiPS) cell-based regenerative medicine. Biologically relevant systems to assess functionality of the engineered vessels in vivo are equally important for such development. Here, we report a unique approach for the derivation of endothelial precursor cells from hiPS cells using a triple combination of selection markersCD34, neuropilin 1, and human kinase insert domain-containing receptorand an efficient 2D culture system for hiPS cell-derived endothelial precursor cell expansion. With these methods, we successfully generated endothelial cells (ECs) from hiPS cells obtained from healthy donors and formed stable functional blood vessels in vivo, lasting for 280 d in mice. In addition, we developed an approach to generate mesenchymal precursor cells (MPCs) from hiPS cells in parallel. Moreover, we successfully generated functional blood vessels in vivo using these ECs and MPCs derived from the same hiPS cell line. These data provide proof of the principle that autologous hiPS cell-derived vascular precursors can be used for in vivo applications, once safety and immunological issues of hiPS-based cellular therapy have been resolved. Additionally, the durability of hiPS-derived blood vessels in vivo demonstrates a potential translation of this approach in long-term vascularization for tissue engineering and treatment of vascular diseases. Of note, we have also successfully generated ECs and MPCs from type 1 diabetic patient-derived hiPS cell lines and use them to generate blood vessels in vivo, which is an important milestone toward clinical translation of this approach. PMID:23861493

Samuel, Rekha; Daheron, Laurence; Liao, Shan; Vardam, Trupti; Kamoun, Walid S.; Batista, Ana; Buecker, Christa; Schfer, Richard; Han, Xiaoxing; Au, Patrick; Scadden, David T.; Duda, Dan G.; Fukumura, Dai; Jain, Rakesh K.

2013-01-01

197

Analysis of blood flow in deformable vessels via a lattice Boltzmann approach  

NASA Astrophysics Data System (ADS)

In this paper, the lattice Boltzmann (LB) method is used in order to simulate non-Newtonian blood flows in deformable vessels. Casson's rheological model is adopted and a local correction to the relaxation time is implemented in order to modify the viscosity. The hyperelastic, hardening and anisotropic behavior of a flexible arterial wall is discussed and a closed-form solution is used to predict the deformed configuration of the vessel. A partitioned staggered-explicit strategy to couple the LB method and such analytical prediction is proposed.

de Rosis, Alessandro

2014-11-01

198

The Emergence of Blood and Blood Vessels in the Embryo and Its Relevance to Postnatal Biology and Disease  

NASA Astrophysics Data System (ADS)

Blood and blood vessels develop in parallel within mammalian systems, and this temporal and spatial association has led to the confirmation of an endothelial origin of hematopoiesis. The extraembryonic yolk sac and aorto-gonado-mesonephros (AGM) region both contain a specialized population of endothelial cells ("hemogenic endothelium") that function to produce hematopoietic stem and progenitor cells, which then differentiate to provide the full complement of blood cells within the developing embryo and furthermore in the adult system. Therefore, this population has great therapeutic potential in the fields of regenerative medicine and tissue engineering. This chapter reviews the development of the vascular and hematopoietic systems, characterization and function of the hemogenic endothelium within embryonic and embryonic stem cell (ES cell) models, and speculate on the presence of such a population within the adult system. In order to harness this endothelial subtype for clinical application, we must understand both the normal functions of these cells and the potential for misregulation in disease states.

Sills, Tiffany M.; Hirschi, Karen K.

199

Early postnatal growth of skeletal muscle blood vessels of the rat.  

PubMed

The development of blood vessels during the first three postnatal weeks was studied in the ventral stripe of the spinotrapezius muscle of the rat by use of India ink-gelatine injections, and electron microscopy. The number of terminal arterioles and collecting venules remained unchanged postnatally in the observed area. A remarkable proximodistal gradient of vascular development was apparent: while the basic structure of the hilar vessels remained unchanged in the time studied, the intramuscular arteries and veins matured gradually. More peripherally, gradual maturation of terminal and precapillary arterioles was observed. The capillary endothelium and the pericytes showed immature features, and remained unchanged during the time studied. An intense rebuilding activity was found in the endothelial cells of the growing venules, expressed by various forms of gaps, covered by an intact basal lamina and pericytes. Numerous mast cells and macrophages were found along all vessels. Intramuscular lymphatics were not present prior to the first postnatal week. PMID:8137394

Stingl, J; Rhodin, J A

1994-03-01

200

Comparison of two algorithms in the automatic segmentation of blood vessels in fundus images  

NASA Astrophysics Data System (ADS)

Effective timing and treatment are critical to saving the sight of patients with diabetes. Lack of screening, as well as a shortage of ophthalmologists, help contribute to approximately 8,000 cases per year of people who lose their sight to diabetic retinopathy, the leading cause of new cases of blindness [1] [2]. Timely treatment for diabetic retinopathy prevents severe vision loss in over 50% of eyes tested [1]. Fundus images can provide information for detecting and monitoring eye-related diseases, like diabetic retinopathy, which if detected early, may help prevent vision loss. Damaged blood vessels can indicate the presence of diabetic retinopathy [9]. So, early detection of damaged vessels in retinal images can provide valuable information about the presence of disease, thereby helping to prevent vision loss. Purpose: The purpose of this study was to compare the effectiveness of two blood vessel segmentation algorithms. Methods: Fifteen fundus images from the STARE database were used to develop two algorithms using the CVIPtools software environment. Another set of fifteen images were derived from the first fifteen and contained ophthalmologists' hand-drawn tracings over the retinal vessels. The ophthalmologists' tracings were used as the "gold standard" for perfect segmentation and compared with the segmented images that were output by the two algorithms. Comparisons between the segmented and the hand-drawn images were made using Pratt's Figure of Merit (FOM), Signal-to-Noise Ratio (SNR) and Root Mean Square (RMS) Error. Results: Algorithm 2 has an FOM that is 10% higher than Algorithm 1. Algorithm 2 has a 6%-higher SNR than Algorithm 1. Algorithm 2 has only 1.3% more RMS error than Algorithm 1. Conclusions: Algorithm 1 extracted most of the blood vessels with some missing intersections and bifurcations. Algorithm 2 extracted all the major blood vessels, but eradicated some vessels as well. Algorithm 2 outperformed Algorithm 1 in terms of visual clarity, FOM and SNR. The performances of these algorithms show that they have an appreciable amount of potential in helping ophthalmologists detect the severity of eye-related diseases and prevent vision loss.

LeAnder, Robert; Chowdary, Myneni Sushma; Mokkapati, Swapnasri; Umbaugh, Scott E.

2008-03-01

201

Blood Vessels Pattern Heparan Sulfate Gradients between Their Apical and Basolateral Aspects  

PubMed Central

A hallmark of immune cell trafficking is directional guidance via gradients of soluble or surface bound chemokines. Vascular endothelial cells produce, transport and deposit either their own chemokines or chemokines produced by the underlying stroma. Endothelial heparan sulfate (HS) was suggested to be a critical scaffold for these chemokine pools, but it is unclear how steep chemokine gradients are sustained between the lumenal and ablumenal aspects of blood vessels. Addressing this question by semi-quantitative immunostaining of HS moieties around blood vessels with a pan anti-HS IgM mAb, we found a striking HS enrichment in the basal lamina of resting and inflamed post capillary skin venules, as well as in high endothelial venules (HEVs) of lymph nodes. Staining of skin vessels with a glycocalyx probe further suggested that their lumenal glycocalyx contains much lower HS density than their basolateral extracellular matrix (ECM). This polarized HS pattern was observed also in isolated resting and inflamed microvascular dermal cells. Notably, progressive skin inflammation resulted in massive ECM deposition and in further HS enrichment around skin post capillary venules and their associated pericytes. Inflammation-dependent HS enrichment was not compromised in mice deficient in the main HS degrading enzyme, heparanase. Our results suggest that the blood vasculature patterns steep gradients of HS scaffolds between their lumenal and basolateral endothelial aspects, and that inflammatory processes can further enrich the HS content nearby inflamed vessels. We propose that chemokine gradients between the lumenal and ablumenal sides of vessels could be favored by these sharp HS scaffold gradients. PMID:24465652

Stoler-Barak, Liat; Moussion, Christine; Shezen, Elias; Hatzav, Miki; Sixt, Michael; Alon, Ronen

2014-01-01

202

Blood vessel uptake and metabolism of organic nitrates in the rat  

SciTech Connect

Recent reports have suggested that the unusual pharmacokinetics observed for nitroglycerin (NTG) and isosorbide dinitrate (ISDN) may be partially explained by extensive uptake and/or metabolism of these drugs by vascular and other extrahepatic tissues. Using the rat as an animal model, this hypothesis was examined by in vivo intravessel NTG and (/sup 14/C)ISDN infusion and injection into various vessel segments, viz. the femoral vein, inferior vena cava (IVC: lower, middle and upper) and the aorta. NTG and (/sup 14/C)ISDN concentrations were determined in these blood vessels and in plasma. Blood vessel segments nearest the input site had the greatest amounts of nitrate, whereas segments further away from the input site had progressively less nitrate, with the exception of aorta, which appeared to take up NTG less extensively, on a per weight of vessel basis, than the IVC. Blood vessel NTG concentrations (nanogram per gram) were generally higher (10-fold) and declined about twice as slowly as NTG plasma concentrations (nanograms per milliliter). (/sup 14/C)NTG and (/sup 14/C)ISDN were also incubated with cofactors in IVC, aorta, abdominal muscle, lung and liver. The amounts of nitrate metabolites formed from parent drug were larger in each extrahepatic tissue incubation than in the controls (P less than .05). The results are consistent with the hypothesis that vascular and other extrahepatic tissues can take up and/or metabolize organic nitrates. The data appear to provide a partial explanation for the large systemic clearance seen with nitrates and appear consistent with existing mechanistic hypotheses for the vascular action of these compounds.

Fung, H.L.; Sutton, S.C.; Kamiya, A.

1984-02-01

203

Ho:YAG laser irradiation in blood vessel as a vasodilator: ex vivo study  

NASA Astrophysics Data System (ADS)

We studied Ho:YAG laser irradiation in blood vessel as a vasodilator ex vivo. We thought that the Ho:YAG laser-induced bubble expansion might be able to dilate the vessel because we found the vessel wall expansion after the Ho:YAG laser irradiation, that is steady deformation, in the vessel ex vivo. There have been many reports regarding to the Ho:YAG laser irradiation in the vessel. Most of studies concentrated on the interaction between Ho:YAG laser irradiation and vessel wall to investigate side effect on Ho:YAG laser angioplasty. We proposed to use the Ho:YAG laser-induced bubble expansion as a vasodilator. We studied vasodilation effect of the Ho:YAG laser-induced bubble ex vivo. The flash lamp excited Ho:YAG laser surgical unit (IH102, NIIC, Japan) (?=2.1?m) was used. The laser energy was delivered by a silica glass fiber (outer diameter: 1000?m, core diameter: 600?m). The laser-induced bubble was generated in the extracted fresh porcine carotid artery with the warmed saline perfusion. The laser energy at the fiber tip was ranging from 170-1300mJ per pulse. Number of the laser irradiation was ranged from 20pulses to 100pulses. The outer diameter of the vessel was observed. To examine the change in mechanical properties of the vessel wall, the stress-strain curve of the laser-irradiated vessel was measured. Birefringence observation and microscopic observation of staining specimen were performed. When the laser energy was set to 1300mJ per pulse, the outer diameter of the vessel after the laser irradiation was expanded by 1.4 times comparing with that of before the laser irradiation and the dilatation effect was kept even at 10minutes after the irradiation. The elasticity modulus of the artery by collagen was changed by the laser irradiation. In the polarized microscopic observation, the brightness of the intimal side of the vessel is increased comparing with that of the normal. We think this brightness increasing may be attributed to birefringence change by the arrangement of stretched collagen fiber. We suppose it is likely to be able to use the Ho:YAG laser irradiation as a temporary vasodilater tool in spite of further study should be performed.

Nakatani, E.; Iwasaki, T.; Kaneko, K.; Shimazaki, N.; Arai, T.

2007-02-01

204

Painting blood vessels and atherosclerotic plaques with an adhesive drug depot  

PubMed Central

The treatment of diseased vasculature remains challenging, in part because of the difficulty in implanting drug-eluting devices without subjecting vessels to damaging mechanical forces. Implanting materials using adhesive forces could overcome this challenge, but materials have previously not been shown to durably adhere to intact endothelium under blood flow. Marine mussels secrete strong underwater adhesives that have been mimicked in synthetic systems. Here we develop a drug-eluting bioadhesive gel that can be locally and durably glued onto the inside surface of blood vessels. In a mouse model of atherosclerosis, inflamed plaques treated with steroid-eluting adhesive gels had reduced macrophage content and developed protective fibrous caps covering the plaque core. Treatment also lowered plasma cytokine levels and biomarkers of inflammation in the plaque. The drug-eluting devices developed here provide a general strategy for implanting therapeutics in the vasculature using adhesive forces and could potentially be used to stabilize rupture-prone plaques. PMID:23236189

Kastrup, Christian J.; Nahrendorf, Matthias; Figueiredo, Jose Luiz; Lee, Haeshin; Kambhampati, Swetha; Lee, Timothy; Cho, Seung-Woo; Gorbatov, Rostic; Iwamoto, Yoshiko; Dang, Tram T.; Dutta, Partha; Yeon, Ju Hun; Cheng, Hao; Pritchard, Christopher D.; Vegas, Arturo J.; Siegel, Cory D.; MacDougall, Samantha; Okonkwo, Michael; Thai, Anh; Stone, James R.; Coury, Arthur J.; Weissleder, Ralph; Langer, Robert; Anderson, Daniel G.

2012-01-01

205

Multiscale 3D Model of Platelet-Vessel Wall Interactions in Blood Flow  

E-print Network

Platelet adhesion to the injury site of the blood vessel wall is a critical step in blood clot formation and an important biomedical problem. Platelets aggregate at the injury site through tethering and rolling on the injured endothelium layer expressing surface-bound von Willebrand factor (vWF) during the initial stage of the blood clot formation. A three-dimensional multiscale model is introduced to simulate receptor-mediated platelet adhesion to substrate exposed with vWF under different shear rates of blood flow. The modeling approach combines Lattice Boltzmann method for simulating flow, hybrid cell membrane model to represent physiological elastic properties of a platelet and stochastic receptor-ligand binding model to describe biologically justified adhesion kinetics. Multiscale model is implemented on the GPUs cluster for speeding up simulations. The model is calibrated by comparing simulated adhesive properties of a platelet with the in vitro experimental data under different flow rates.

Wu, Ziheng; Alber, Mark

2013-01-01

206

Platelet Motion near a Vessel Wall or Thrombus Surface in Two-Dimensional Whole Blood Simulations  

PubMed Central

Computational simulations using a two-dimensional lattice-Boltzmann immersed boundary method were conducted to investigate the motion of platelets near a vessel wall and close to an intravascular thrombus. Physiological volume fractions of deformable red blood cells and rigid platelet-size elliptic particles were studied under arteriolar flow conditions. Tumbling of platelets in the red-blood-cell depleted zone near the vessel walls was strongly influenced by nearby red blood cells. The thickness of the red-blood-cell depleted zone was greatly reduced near a thrombus, and platelets in this zone were pushed close to the surface of the thrombus to distances that would facilitate their cohesion to it. The distance, nature, and duration of close platelet-thrombus encounters were influenced by the porosity of the thrombus. The strong influence on platelet-thrombus encounters of red-blood-cell motion and thrombus porosity must be taken into account to understand the dynamics of platelet attachment to a growing thrombus. PMID:23601323

Skorczewski, Tyler; Erickson, LindsayCrowl; Fogelson, Aaron L.

2013-01-01

207

?-tocopherol increased nitric oxide synthase activity in blood vessels of spontaneously hypertensive rats  

Microsoft Academic Search

Antioxidant protection provided by different doses of ?-tocopherol was compared by determining nitric oxide synthase (NOS) activity in blood vessels of spontaneously hypertensive rats (SHR) treated with ?-tocopherol.SHR were divided into four groups namely hypertensive control (C), treatment with 17 mg of ?-tocopherol\\/kg diet (?1), 34 mg of ?-tocopherol\\/kg diet (?2), and 170 mg of ?-tocopherol\\/kg diet (?3). Wister Kyoto

Mohammad Ali Newaz; N. N. A. Nawal; C. H. Rohaizan; N. Muslim; A. Gapor

1999-01-01

208

Stanford University researchers find that dual-action protein better restricts blood vessel formation:  

Cancer.gov

In a paper published online Aug. 8 in the Proceedings of the National Academy of Sciences, researchers at Stanford University describe the creation of a new type of engineered protein that is significantly more effective at preventing the formation of blood vessels by targeting not one, but two of the chemical receptors that control the creation of new capillaries -- a process known as angiogenesis. The study shows that the new protein blocks both receptors.

209

Emory University researchers find new pathway for regulation of blood vessel growth in cancer  

Cancer.gov

Researchers at Winship Cancer Institute of Emory University have identified a new function for a gene that normally prevents the development of cancer. Scientists had known that the gene, which encodes a protein called p14 ARF, works inside the cell to control proliferation and division. The Winship team discovered that p14 ARF also regulates tumor-induced angiogenesis, the process by which growing cancers attract new blood vessels.

210

Sonic hedgehog is required for the assembly and remodeling of branchial arch blood vessels  

PubMed Central

Sonic hedgehog (Shh) is a morphogen involved in many developmental processes. Injection of cells (5E1) that produce a Shh blocking antibody, causes an attenuation of the Shh response, and this causes vascular malformations and impaired remodeling characterized by hemorrhages and protrusions of the anterior cardinal vein and outflow tract, delayed fusion of the dorsal aortae, impaired branching of the internal carotid artery and delayed remodeling of the aortic arches. Distribution of smooth muscle cells in the vessel wall is unchanged. In 5E1 injected embryos we also observed impaired assembly of endothelial cells into vascular tubes, particularly in the sixth branchial arch, around the anterior cardinal vein and around dorsal aorta. In 5E1 treated embryos, increased numbers of macrophage-like cells, apoptotic cells and a decreased level of proliferation were observed in head mesenchyme. Together these observations show that Shh signaling is required at multiple stages for proper vessel formation and remodeling. PMID:18570256

Kolesov, Hana; Roelink, Henk; Grim, Milos

2011-01-01

211

Schlemm's Canal Is a Unique Vessel with a Combination of Blood Vascular and Lymphatic Phenotypes that Forms by a Novel Developmental Process  

PubMed Central

Schlemm's canal (SC) plays central roles in ocular physiology. These roles depend on the molecular phenotypes of SC endothelial cells (SECs). Both the specific phenotype of SECs and development of SC remain poorly defined. To allow a modern and extensive analysis of SC and its origins, we developed a new whole-mount procedure to visualize its development in the context of surrounding tissues. We then applied genetic lineage tracing, specific-fluorescent reporter genes, immunofluorescence, high-resolution confocal microscopy, and three-dimensional (3D) rendering to study SC. Using these techniques, we show that SECs have a unique phenotype that is a blend of both blood and lymphatic endothelial cell phenotypes. By analyzing whole mounts of postnatal mouse eyes progressively to adulthood, we show that SC develops from blood vessels through a newly discovered process that we name canalogenesis. Functional inhibition of KDR (VEGFR2), a critical receptor in initiating angiogenesis, shows that this receptor is required during canalogenesis. Unlike angiogenesis and similar to stages of vasculogenesis, during canalogenesis tip cells divide and form branched chains prior to vessel formation. Differing from both angiogenesis and vasculogenesis, during canalogenesis SECs express Prox1, a master regulator of lymphangiogenesis and lymphatic phenotypes. Thus, SC development resembles a blend of vascular developmental programs. These advances define SC as a unique vessel with a combination of blood vascular and lymphatic phenotypes. They are important for dissecting its functions that are essential for ocular health and normal vision. PMID:25051267

Kizhatil, Krishnakumar; Ryan, Margaret; Marchant, Jeffrey K.; Henrich, Stephen; John, Simon W. M.

2014-01-01

212

Promoting blood vessel growth in ischemic diseases: challenges in translating preclinical potential into clinical success  

PubMed Central

Angiogenic therapy, which involves the use of an exogenous stimulus to promote blood vessel growth, is an attractive approach for the treatment of ischemic diseases. It has been shown in animal models that the stimulation of blood vessel growth leads to the growth of the whole vascular tree, improvement of ischemic tissue perfusion and improved muscle aerobic energy metabolism. However, very few positive results have been gained from Phase 2 and 3 clinical angiogenesis trials. Many reasons have been given for the failures of clinical trials, including poor transgene expression (in gene-therapy trials) and instability of the vessels induced by therapy. In this Review, we discuss the selection of preclinical models as one of the main reasons why clinical translation has been unsuccessful thus far. This issue has received little attention, but could have had dramatic implications on the expectations of clinical trials. We highlight crucial differences between human patients and animal models with regards to blood flow and pressure, as well as issues concerning the chronic nature of ischemic diseases in humans. We use these as examples to demonstrate why the results from preclinical trials might have overestimated the efficacy of angiogenic therapies developed to date. We also suggest ways in which currently available animal models of ischemic disease could be improved to better mimic human disease conditions, and offer advice on how to work with existing models to avoid overestimating the efficacy of new angiogenic therapies. PMID:23471910

Dragneva, Galina; Korpisalo, Petra; Yl-Herttuala, Seppo

2013-01-01

213

Development of blood vessel-related radiation damage in the fimbria of the central nervous system  

SciTech Connect

The identification problem of the dose-limiting tissue component was investigated in the CNS of rats. Moderate single doses of radiation, ranging from 20 to 25 Gy were applied to the brain of adult female rats. The sequence of events was analyzed by scoring a series of morphological changes in one of the white matter structures that appears to represent a sensitive location, that is the fimbria hippocampi. The previously defined Tissue Injury Unit, characterized by a dilation of the blood vessel lumen, a thickening of the blood vessel wall, an enlargement of endothelial cell nuclei, and a hypertrophy of the adjacent astrocytes which represents a combined score of four different, but related histological changes, proved to be slightly more sensitive and responsive than the earliest recognizable changes in the neurological structures, that is demyelination. In addition, the incidence of demyelination could be expressed as a function of the intensity of the Tissue Injury Unit. These findings can be interpreted as an additional indication that blood vessel changes and the hypertrophy of the perivascular astrocytes precede degenerative changes in the white matter of the CNS after moderate doses of X rays.

Reinhold, H.S.; Calvo, W.; Hopewell, J.W.; van der Berg, A.P. (Radiobiological Institute TNO, Rijswijk (Netherland))

1990-01-01

214

A heat-shock protein axis regulates VEGFR2 proteolysis, blood vessel development and repair.  

PubMed

Vascular endothelial growth factor A (VEGF-A) binds to the VEGFR2 receptor tyrosine kinase, regulating endothelial function, vascular physiology and angiogenesis. However, the mechanism underlying VEGFR2 turnover and degradation in this response is unclear. Here, we tested a role for heat-shock proteins in regulating the presentation of VEGFR2 to a degradative pathway. Pharmacological inhibition of HSP90 stimulated VEGFR2 degradation in primary endothelial cells and blocked VEGF-A-stimulated intracellular signaling via VEGFR2. HSP90 inhibition stimulated the formation of a VEGFR2-HSP70 complex. Clathrin-mediated VEGFR2 endocytosis is required for this HSP-linked degradative pathway for targeting VEGFR2 to the endosome-lysosome system. HSP90 perturbation selectively inhibited VEGF-A-stimulated human endothelial cell migration in vitro. A mouse femoral artery model showed that HSP90 inhibition also blocked blood vessel repair in vivo consistent with decreased endothelial regeneration. Depletion of either HSP70 or HSP90 caused defects in blood vessel formation in a transgenic zebrafish model. We conclude that perturbation of the HSP70-HSP90 heat-shock protein axis stimulates degradation of endothelial VEGFR2 and modulates VEGF-A-stimulated intracellular signaling, endothelial cell migration, blood vessel development and repair. PMID:23139789

Bruns, Alexander F; Yuldasheva, Nadira; Latham, Antony M; Bao, Leyuan; Pellet-Many, Caroline; Frankel, Paul; Stephen, Sam L; Howell, Gareth J; Wheatcroft, Stephen B; Kearney, Mark T; Zachary, Ian C; Ponnambalam, Sreenivasan

2012-01-01

215

A Heat-Shock Protein Axis Regulates VEGFR2 Proteolysis, Blood Vessel Development and Repair  

PubMed Central

Vascular endothelial growth factor A (VEGF-A) binds to the VEGFR2 receptor tyrosine kinase, regulating endothelial function, vascular physiology and angiogenesis. However, the mechanism underlying VEGFR2 turnover and degradation in this response is unclear. Here, we tested a role for heat-shock proteins in regulating the presentation of VEGFR2 to a degradative pathway. Pharmacological inhibition of HSP90 stimulated VEGFR2 degradation in primary endothelial cells and blocked VEGF-A-stimulated intracellular signaling via VEGFR2. HSP90 inhibition stimulated the formation of a VEGFR2-HSP70 complex. Clathrin-mediated VEGFR2 endocytosis is required for this HSP-linked degradative pathway for targeting VEGFR2 to the endosome-lysosome system. HSP90 perturbation selectively inhibited VEGF-A-stimulated human endothelial cell migration in vitro. A mouse femoral artery model showed that HSP90 inhibition also blocked blood vessel repair in vivo consistent with decreased endothelial regeneration. Depletion of either HSP70 or HSP90 caused defects in blood vessel formation in a transgenic zebrafish model. We conclude that perturbation of the HSP70-HSP90 heat-shock protein axis stimulates degradation of endothelial VEGFR2 and modulates VEGF-A-stimulated intracellular signaling, endothelial cell migration, blood vessel development and repair. PMID:23139789

Bruns, Alexander F.; Yuldasheva, Nadira; Latham, Antony M.; Bao, Leyuan; Pellet-Many, Caroline; Frankel, Paul; Stephen, Sam L.; Howell, Gareth J.; Wheatcroft, Stephen B.; Kearney, Mark T.; Zachary, Ian C.; Ponnambalam, Sreenivasan

2012-01-01

216

Neurovascular signals suggest a propagation mechanism for endogenous stem cell activation along blood vessels.  

PubMed

Stem cell-based therapies for central nervous system disorders are intensely pursued. Such approaches can be divided into two categories: Transplantation-based, and those that aim to pharmacologically target the endogenous stem cell population in the tissue. Endogenous stem cell - based strategies avoid the problem of immune incompatibility between the host and the grafted cells. They also avoid the placement of a large amount of cells in confined areas, a manipulation which alters the characteristics of the neurovascular microenvironment. We show here that massive pharmacological activation (increase in cell numbers) of the endogenous neural stem cell population in the adult rodent brain maintains the cytoarchitecture of the neurovascular niche. Distances between adjacent stem cells (identified by expression of Hes3) are maintained above a minimum. Hes3+ cells maintain their physical association with blood vessels. These results also suggest a mechanism by which the activation signal from the lateral ventricle can be propagated to areas a long distance away from the lateral ventricles, through autocrine/paracrine actions between adjacent Hes3+ cells, along blood vessels. Finally, powerful effects of angiopoietin 2 on Hes3+ cells help explain the prevalence of proliferating endogenous neural stem cells close to the subventricular zone (an area of high angiopoietin 2 concentration) and the quiescent state of stem cells away from the ventricles and their tight physical association with blood vessels (which express high levels of angiopoietin 1, a cytokine that opposes angiopoietin 2 functions). PMID:23131162

Masjkur, Jimmy; Rueger, Maria Adele; Bornstein, Stefan R; McKay, Ron; Androutsellis-Theotokis, Andreas

2012-11-01

217

Transcranial imaging of functional cerebral hemodynamic changes in single blood vessels using in vivo photoacoustic microscopy  

PubMed Central

Optical imaging of changes in total hemoglobin concentration (HbT), cerebral blood volume (CBV), and hemoglobin oxygen saturation (SO2) provides a means to investigate brain hemodynamic regulation. However, high-resolution transcranial imaging remains challenging. In this study, we applied a novel functional photoacoustic microscopy technique to probe the responses of single cortical vessels to left forepaw electrical stimulation in mice with intact skulls. Functional changes in HbT, CBV, and SO2 in the superior sagittal sinus and different-sized arterioles from the anterior cerebral artery system were bilaterally imaged with unambiguous 36 65-?m2 spatial resolution. In addition, an early decrease of SO2 in single blood vessels during activation (i.e., the initial dip') was observed. Our results indicate that the initial dip occurred specifically in small arterioles of activated regions but not in large veins. This technique complements other existing imaging approaches for the investigation of the hemodynamic responses in single cerebral blood vessels. PMID:22472612

Liao, Lun-De; Lin, Chin-Teng; Shih, Yen-Yu I; Duong, Timothy Q; Lai, Hsin-Yi; Wang, Po-Hsun; Wu, Robby; Tsang, Siny; Chang, Jyh-Yeong; Li, Meng-Lin; Chen, You-Yin

2012-01-01

218

In vivo Bioimaging as a Novel Strategy to Detect Doxorubicin-Induced Damage to Gonadal Blood Vessels  

PubMed Central

Introduction Chemotherapy may induce deleterious effects in normal tissues, leading to organ damage. Direct vascular injury is the least characterized side effect. Our aim was to establish a real-time, in vivo molecular imaging platform for evaluating the potential vascular toxicity of doxorubicin in mice. Methods Mice gonads served as reference organs. Mouse ovarian or testicular blood volume and femoral arterial blood flow were measured in real-time during and after doxorubicin (8 mg/kg intravenously) or paclitaxel (1.2 mg/kg) administration. Ovarian blood volume was imaged by ultrasound biomicroscopy (Vevo2100) with microbubbles as a contrast agent whereas testicular blood volume and blood flow as well as femoral arterial blood flow was imaged by pulse wave Doppler ultrasound. Visualization of ovarian and femoral microvasculature was obtained by fluorescence optical imaging system, equipped with a confocal fiber microscope (Cell-viZio). Results Using microbubbles as a contrast agent revealed a 33% (P<0.01) decrease in ovarian blood volume already 3 minutes after doxorubicin injection. Doppler ultrasound depicted the same phenomenon in testicular blood volume and blood flow. The femoral arterial blood flow was impaired in the same fashion. Cell-viZio imaging depicted a pattern of vessels' injury at around the same time after doxorubicin injection: the wall of the blood vessels became irregular and the fluorescence signal displayed in the small vessels was gradually diminished. Paclitaxel had no vascular effect. Conclusion We have established a platform of innovative high-resolution molecular imaging, suitable for in vivo imaging of vessels' characteristics, arterial blood flow and organs blood volume that enable prolonged real-time detection of chemotherapy-induced effects in the same individuals. The acute reduction in gonadal and femoral blood flow and the impairment of the blood vessels wall may represent an acute universal doxorubicin-related vascular toxicity, an initial event in organ injury. PMID:21931602

Tzabari, Moran; Tsarfaty, Galia; Stemmer, Salomon M.; Shalgi, Ruth

2011-01-01

219

Where do the platelets go? A simulation study of fully resolved blood flow through aneurysmal vessels  

PubMed Central

Despite the importance of platelets in the formation of a thrombus, their transport in complex flows has not yet been studied in detail. In this paper we simulated red blood cells and platelets to explore their transport behaviour in aneurysmal geometries. We considered two aneurysms with different aspect ratios (AR = 1.0, 2.0) in the presence of fast and slow blood flows (Re = 10, 100), and examined the distributions of the cells. Low velocities in the parent vessel resulted in a large stagnation zone inside the cavity, leaving the initial distribution almost unchanged. In fast flows, an influx of platelets into the aneurysm was observed, leading to an elevated concentration. The connection of the platelet-rich cell-free layer (CFL) with the outer regions of the recirculation zones leads to their increased platelet concentration. These platelet-enhanced recirculation zones produced a diverse distribution of cells inside the aneurysm, for the different aspect ratios. A thin red blood CFL that was occupied by platelets was observed on the top of the wide-necked aneurysm, whereas a high-haematocrit region very close to the vessel wall was present in the narrow-necked case. The simulations revealed that non-trivial distributions of red blood cells and platelets are possible inside aneurysmal geometries, giving rise to several hypotheses on the formation of a thrombus, as well as to the wall weakening and the possible rupture of an aneurysm. PMID:24427532

Mountrakis, L.; Lorenz, E.; Hoekstra, A. G.

2013-01-01

220

Aldehyde dehydrogenase-independent bioactivation of nitroglycerin in porcine and bovine blood vessels.  

PubMed

The vascular bioactivation of the antianginal drug nitroglycerin (GTN), yielding 1,2-glycerol dinitrate and nitric oxide or a related activator of soluble guanylate cyclase, is catalyzed by aldehyde dehydrogenase-2 (ALDH2) in rodent and human blood vessels. The essential role of ALDH2 has been confirmed in many studies and is considered as general principle of GTN-induced vasodilation in mammals. However, this view is challenged by an early report showing that diphenyleneiodonium, which we recently characterized as potent ALDH2 inhibitor, has no effect on GTN-induced relaxation of bovine coronary arteries (De La Lande et al., 1996). We investigated this issue and found that inhibition of ALDH2 attenuates GTN-induced coronary vasodilation in isolated perfused rat hearts but has no effect on relaxation to GTN of bovine and porcine coronary arteries. This observation is explained by low levels of ALDH2 protein expression in bovine coronary arteries and several types of porcine blood vessels. ALDH2 mRNA expression and the rates of GTN denitration were similarly low, excluding a significant contribution of ALDH2 to the bioactivation of GTN in these vessels. Attempts to identify the responsible pathway with enzyme inhibitors did not provide conclusive evidence for the involvement of ALDH3A1, cytochrome P450, or GSH-S-transferase. Thus, the present manuscript describes a hitherto unrecognized pathway of GTN bioactivation in bovine and porcine blood vessels. If present in the human vasculature, this pathway might contribute to the therapeutic effects of organic nitrates that are not metabolized by ALDH2. PMID:25576686

Neubauer, Regina; Wlkart, Gerald; Opelt, Marissa; Schwarzenegger, Christine; Hofinger, Marielies; Neubauer, Andrea; Kollau, Alexander; Schmidt, Kurt; Schrammel, Astrid; Mayer, Bernd

2015-02-15

221

Advances in probing the blood vessels of the human brain using magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging offers a marvelous means to probe the vasculature of the human body non-invasively. The first major advances came when the physics of the effects of motion in MRI were first understood well enough that new methods could be designed to compensate for the motion. This led to the development of MR angiography. The second major advance occurred when a contrast agent was used to enhance the signal from vessels independent of blood flow. This made it possible to image much smaller vessels because of the increased signal-to-noise ratio. The third major advance occurred when the susceptibility of the venous blood was used to create a new contrast unique to veins even in the presence of the contrast agent to enhance their signal. The fourth advance is close behind with the potential to use the susceptibility to measure the local oxygen content. Each of these advances involved some interesting physics and raised questions about local magnetic field effects, some of which remain unanswered yet today. We will show results from the first three levels with hints at how to proceed to the fourth. The development of this technology has important clinical implications. With new higher relaxivity contrast agents and higher field magnets coming on the market, the possibility to image vessels down to on the order of 100 microns may be viable. Each advance has enhanced the range of applications from just imaging vessels to occult vascular disease, trauma, the detection of blood products, and physiologic function of the tissue itself.

Haacke, E. Mark

2002-03-01

222

Aldehyde dehydrogenase-independent bioactivation of nitroglycerin in porcine and bovine blood vessels  

PubMed Central

The vascular bioactivation of the antianginal drug nitroglycerin (GTN), yielding 1,2-glycerol dinitrate and nitric oxide or a related activator of soluble guanylate cyclase, is catalyzed by aldehyde dehydrogenase-2 (ALDH2) in rodent and human blood vessels. The essential role of ALDH2 has been confirmed in many studies and is considered as general principle of GTN-induced vasodilation in mammals. However, this view is challenged by an early report showing that diphenyleneiodonium, which we recently characterized as potent ALDH2 inhibitor, has no effect on GTN-induced relaxation of bovine coronary arteries (De La Lande et al., 1996). We investigated this issue and found that inhibition of ALDH2 attenuates GTN-induced coronary vasodilation in isolated perfused rat hearts but has no effect on relaxation to GTN of bovine and porcine coronary arteries. This observation is explained by low levels of ALDH2 protein expression in bovine coronary arteries and several types of porcine blood vessels. ALDH2 mRNA expression and the rates of GTN denitration were similarly low, excluding a significant contribution of ALDH2 to the bioactivation of GTN in these vessels. Attempts to identify the responsible pathway with enzyme inhibitors did not provide conclusive evidence for the involvement of ALDH3A1, cytochrome P450, or GSH-S-transferase. Thus, the present manuscript describes a hitherto unrecognized pathway of GTN bioactivation in bovine and porcine blood vessels. If present in the human vasculature, this pathway might contribute to the therapeutic effects of organic nitrates that are not metabolized by ALDH2. PMID:25576686

Neubauer, Regina; Wlkart, Gerald; Opelt, Marissa; Schwarzenegger, Christine; Hofinger, Marielies; Neubauer, Andrea; Kollau, Alexander; Schmidt, Kurt; Schrammel, Astrid; Mayer, Bernd

2015-01-01

223

Drug that blocks blood vessel growth may be beneficial in treating AIDS-related Kaposis sarcoma  

Cancer.gov

Patients with an AIDS-associated cancer, Kaposi's sarcoma (KS), showed improvement after receiving the combination of bevacizumab, a cancer drug that blocks the growth of new blood vessels, and highly active antiretroviral therapy (HAART).

224

Blood Vessel Classification into Arteries and Veins in Retinal Claudia Kondermann and Daniel Kondermanna and Michelle Yanb  

E-print Network

Blood Vessel Classification into Arteries and Veins in Retinal Images Claudia Kondermann and Daniel for DR are abnormally wide veins leading to an unusually low ratio of the average diameter of arteries symptom being an abnormal AVR value. To determine it, a classification of vessels as arteries or veins

Cremers, Daniel

225

Magnetic navigation system for the precise helical and translational motions of a microrobot in human blood vessels  

NASA Astrophysics Data System (ADS)

Different magnetic navigation systems (MNSs) have been investigated for the wireless manipulation of microrobots in human blood vessels. Here we propose a MNS and methodology for generation of both the precise helical and translational motions of a microrobot to improve its maneuverability in complex human blood vessel. We then present experiments demonstrating the helical and translational motions of a spiral-type microrobot to verify the proposed MNS.

Jeon, S. M.; Jang, G. H.; Choi, H. C.; Park, S. H.; Park, J. O.

2012-04-01

226

The phylogeny of the fine structure of blood vessels and lymphatics: similarities and differences.  

PubMed

As animals increased in size, various modifications had to come into being to carry nutrients and waste around the body. Different phyla solved the various problems differently; sometimes there was convergent evolution. In invertebrates the endothelial cells are often widely separated from each other; permeability is limited by the pericyte layer; the reverse occurs in vertebrates. In primitive chordates small peripheral vessels often consist only of the basement membrane, and even this may be partly missing; the more centrally one looks, the more the endothelial cells become continuous. Fenestrae appeared first in the agnatha, but only become common in the elasmobranchs. Increased size and activity necessitated still larger blood hydrostatic pressure and increased blood colloidal osmotic pressures to balance this. Since the permeability of the vessels could not be reduced, much more protein (and fluid) had to leak to the tissues. So the lymphatic system had to evolve. This is first seen in the torpedoes and fully evolved in the bony fishes. However, the small venous vessels of the elasmobranchs have openable inter-endothelial junctions and other structures very similar to those of the initial lymphatics. Apart from the absence of fenestrae in lymphatics, or when this system is injected with a tracer, it is not always possible to tell them apart with the electron microscope. There are, however, various differences between them which will help to differentiate them. PMID:3444359

Casley-Smith, J R

1987-12-01

227

Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall  

PubMed Central

It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function. PMID:24671377

Billaud, Marie; Lohman, Alexander W.; Johnstone, Scott R.; Biwer, Lauren A.; Mutchler, Stephanie; Isakson, Brant E.

2014-01-01

228

Engineered blood vessel networks connect to host vasculature via wrapping-and-tapping anastomosis  

PubMed Central

Rapid blood perfusion is critical for postimplantation survival of thick, prevascularized bioartificial tissues. Yet the mechanism by which implanted vascular networks inosculate, or anastomose, with the host vasculature has been unknown, making it difficult to develop optimized strategies for facilitating perfusion. Here we show that implanted vascular networks anastomose with host vessels through a previously unidentified process of wrapping and tapping between the engrafted endothelial cells (ECs) and the host vasculature. At the host-implant interface, implanted ECs first wrap around nearby host vessels and then cause basement membrane and pericyte reorganization and localized displacement of the underlying host endothelium. In this way, the implanted ECs replace segments of host vessels to divert blood flow to the developing implanted vascular network. The process is facilitated by high levels of matrix metalloproteinase-14 and matrix metalloproteinase-9 expressed by the wrapping ECs. These findings open the door to new strategies for improving perfusion of tissue grafts and may have implications for other physiologic and pathologic processes involving postnatal vasculogenesis. PMID:21835951

Cheng, Gang; Liao, Shan; Kit Wong, Hon; Lacorre, Delphine A.; di Tomaso, Emmanuelle; Au, Patrick; Fukumura, Dai; Jain, Rakesh K.

2011-01-01

229

Differences in inositol phosphate production in blood vessels of normotensive and spontaneously hypertensive rats.  

PubMed Central

1. Total inositol phosphate formation was measured in labelled femoral and iliac arteries and veins of 14 week-old spontaneously hypertensive rats (SHR) and age-matched Wistar Kyoto (WKY) controls, either unstimulated or in the presence of noradrenaline. 2. Basal levels of [3H]-inositol phosphates and [3H]-phosphatidylinositol were significantly enhanced in SHR femoral artery, but not in the other 3 vessels, compared with WKY. 3. Noradrenaline stimulated phosphoinositide hydrolysis in all four vessels of SHR and WKY. Pretreatment with prazosin (10(-7)-10(-6) M) but not with yohimbine (10(-7) M), inhibited the noradrenaline-induced inositol phosphate formation indicating an alpha 1-adrenoceptor-mediated response. 4. In the femoral artery of SHR compared to WKY, [3H]-inositol phosphate accumulation induced by noradrenaline (10(-7)-10(-5) M) was significantly reduced when expressed relative to basal values although the response to higher concentrations (10(-4)-10(-3) M) was not altered. In contrast, a significant reduction of inositol phosphates was seen only with 10(-7) M noradrenaline when absolute values were compared. In the other three vessels, no difference in noradrenaline-induced [3H]-inositol phosphate formation was observed between strains. 5. These data suggest that phosphoinositide hydrolysis-mediated by alpha 1-adrenoceptors may be reduced in some but not all blood vessels of adult SHR. PMID:1797298

Vila, E.; Macrae, I. M.; Reid, J. L.

1991-01-01

230

Effect of a soluble surfactant on a finite sized bubble motion in a blood vessel  

PubMed Central

We present detailed results for the motion of a finite sized gas bubble in a blood vessel. The bubble (dispersed phase) size is taken to be such as to nearly occlude the vessel. The bulk medium is treated as a shear thinning Casson fluid and contains a soluble surfactant that adsorbs and desorbs from the interface. Three different vessel sizes, corresponding to a small artery, a large arteriole, and a small arteriole, in normal humans, are considered. The hematocrit (volume fraction of RBCs) has been taken to be 0.45. For arteriolar flow, where relevant, the Fahraeus-Lindqvist effect is taken into account. Bubble motion cause temporal and spatial gradients of shear stress at the cell surface lining the vessel wall as the bubble approaches the cell, moves over it and passes it by. Rapid reversals occur in the sign of the shear stress imparted to the cell surface during this motion. Shear stress gradients together with sign reversals are associated with a recirculation vortex at the rear of the moving bubble. The presence of the surfactant reduces the level of the shear stress gradients imparted to the cell surface as compared to an equivalent surfactant-free system. Our numerical results for bubble shapes and wall shear stresses may help explain phenomena observed in experimental studies related to gas embolism, a significant problem in cardiac surgery and decompression sickness. PMID:20305744

Swaminathan, T. N.; Mukundakrishnan, K.; Ayyaswamy, P. S.; Eckmann, D. M.

2009-01-01

231

Understanding How Space Travel Affects Blood Vessels: Arterial Remodeling and Functional Adaptations Induced by Microgravity  

NASA Technical Reports Server (NTRS)

Ever rise quickly from the couch to get something from the kitchen and suddenly feel dizzy? With a low heart rate and relaxed muscles, the cardiovascular system does not immediately provide the resistance necessary to keep enough blood going to your head. Gravity wins, at least for a short time, before your heart and blood vessels can respond to the sudden change in position and correct the situation. Actually, the human cardiovascular system is quite well adapted to the constant gravitational force of the Earth. When standing, vessels in the legs constrict to prevent blood from collecting in the lower extremities. In the space environment, the usual head-to-foot blood pressure and tissue fluid gradients that exist during the upright posture on Earth are removed. The subsequent shift in fluids from the lower to the upper portions of the body triggers adaptations within the cardiovascular system to accommodate the new pressure and fluid gradients. In animal models that simulate microgravity, the vessels in the head become more robust while those in the lower limbs become thin and lax. Similar changes may also occur in humans during spaceflight and while these adaptations are appropriate for a microgravity environment, they can cause problems when the astronauts return to Earth or perhaps another planet. Astronauts often develop orthostatic intolerance which means they become dizzy or faint when standing upright. This dizziness can persist for a number of days making routine activities difficult. In an effort to understand the physiological details of these cardiovascular adaptations, Dr. Michael Delp at Texas A&M University, uses the rat as a model for his studies. For the experiment flown on STS-107, he will test the hypothesis that blood vessels in the rats' hindlimbs become thinner, weaker, and constrict less in response to pressure changes and to chemical signals when exposed to microgravity. In addition, he will test the hypothesis that arteries in the brain become thicker as a result of microgravity-induced fluid shifts toward the head.

Delp, Michael; Vasques, Marilyn; Aquilina, Rudy (Technical Monitor)

2002-01-01

232

Imaging of subcutaneous blood vessels and flow velocity profiles by optical coherence tomography  

NASA Astrophysics Data System (ADS)

We have applied a compact low power rapid scanning Doppler Optical Coherence Tomography system to monitor multi-dimensional velocity profiles within the complex vessels and simultaneous real-time non-invasive imaging of skin tissues morphology in vivo, in the wavelength range of 1.3-1.5 nm. Optical clearing of skin tissues has been utilized to achieve depth of OCT images up to 1.7 mm. Current approach enables applying low-power (0.4-0.5 mW) and low-noise broadband near-infrared light sources and obtaining OCT images with down to 12 ?m spatial resolution. Two-dimensional time-domain OCT images of complex flow velocity profiles in blood vessel phantom and in vivo subcutaneous human skin tissues are presented. The effect of optical clearing on in vivo images is demonstrated and discussed.

Bonesi, M.; Proskurin, S. G.; Meglinski, I. V.

2010-04-01

233

Simulations of Blood Flow in Plain Cylindrical and Constricted Vessels with Single Cell Resolution  

E-print Network

Understanding the physics of blood is challenging due to its nature as a suspension of soft particles and the fact that typical problems involve different scales. This is valid also for numerical investigations. In fact, many computational studies either neglect the existence of discrete cells or resolve relatively few cells very accurately. The authors recently developed a simple and highly efficient yet still particulate model with the aim to bridge the gap between currently applied methods. The present work focuses on its applicability to confined flows in vessels of diameters up to 100 micrometres. For hematocrit values below 30 percent, a dependence of the apparent viscosity on the vessel diameter in agreement with experimental literature data is found.

Florian Janoschek; Federico Toschi; Jens Harting

2011-05-31

234

Correlation mapping method of OCT for visualization blood vessels in brain  

NASA Astrophysics Data System (ADS)

The burning issue in modern medicine is the diagnosis and treatment of various life-threatening diseases, in particular the diseases of brain. One of them is intracranial hemorrhage (ICH). It occurs especially among newborn babies and is hard-diagnosed. In order to understand the nature of the ICH, the microcirculation of blood, which serves key functions within the body, is analyzed. On this basis a series of experiments was done, in the results of which it was showed, that latent stage of ICH is characterized by decrease of venous blood outflow and the loss of sensitivity of sagittal vein to vasoconstrictor effect of adrenaline. So, stress-related changes of the cerebral venous blood flow (CVBF) can be the source of this disease. In this paper registration CVBF was made with the help of commercially available Thorlabs Swept Source OCT System, using the correlation mapping method. In this method values of correlation coefficient of several images are analyzed. In the result of the algorithm the correlation map was obtained. By the resulting map the diameter of vessels was calculated, which is necessary for examination of effects of adrenalin to the vessels and identification symptoms of ICH.

Izotova, O. A.; Kalyanov, A. L.; Lychagov, V. V.; Semyachkina-Glushkovskaya, O. V.

2013-11-01

235

The effect of complex exercise rehabilitation program on body composition, blood pressure, blood sugar, and vessel elasticity in elderly women with obesity  

PubMed Central

The purpose of this study is to identify what kind of effects complex exercise rehabilitation program has on body composition of female, blood pressure, blood sugar, blood vessel elasticity and find more effective complex exercise program for elderly females. The subjects are selected 30 females applicants in exercise program in City of G and not restricted in mobility to perform the exercise without any particular disorders. Exercise program is a combination of aerobic and strength training with different ratio, for the first 6 months focused on strength training complex exercise, and for next 6 months focused on aerobic exercise. Except for strength training and aerobic exercise, durations for strength, rest, and wrapping-up are equal. The frequency of experiments is 90 min each, 2 times per a week. Body composition, blood pressure, and blood vessel elasticity are tested pre and post experiment to compare the effectiveness of both complex exercises. As results, in the complex exercise program focused on strength training, weight, percent body fat, fat mass, waist hip ratio, systolic blood pressure, and diastolic pressure increased. Blood vessel elasticity maintained its level or slightly decreased. In the complex exercise focused on aerobic exercise, weight, percent body fat, fat mass, waist hip ratio, systolic pressure, and diastolic pressure decreased. Blood vessel elasticity on left foot and right foot are slightly different. Therefore, aerobic exercise is more effective than strength training for old obese females. PMID:24409428

Lee, Eun-Ok; Lee, Kwon-Ho; Kozyreva, Olga

2013-01-01

236

Tauroursodeoxycholic Acid, a bile Acid, promotes blood vessel repair by recruiting vasculogenic progenitor cells.  

PubMed

Although serum bile acid concentrations are approximately 10 M in healthy subjects, the crosstalk between the biliary system and vascular repair has never been investigated. In this study, tauroursodeoxycholic acid (TUDCA) induced dissociation of CD34(+) hematopoietic stem cells (HSCs) from stromal cells by reducing adhesion molecule expression. TUDCA increased CD34(+) /Sca1(+) progenitors in mice peripheral blood (PB), and CD34(+) , CD31(+) , and c-kit(+) progenitors in human PB. In addition, TUDCA increased differentiation of CD34(+) HSCs into EPC lineage cells via Akt activation. EPC invasion was increased by TUDCA, which was mediated by fibroblast activating protein via Akt activation. Interestingly, TUDCA induced integration of EPCs into human aortic endothelial cells (HAECs) by increasing adhesion molecule expression. In the mouse hind limb ischemia model, TUDCA promoted blood perfusion by enhancing angiogenesis through recruitment of Flk-1(+) /CD34(+) and Sca-1(+) /c-kit(+) progenitors into damaged tissue. In GFP(+) bone marrow-transplanted hind limb ischemia, TUDCA induced recruitment of GFP(+) /c-kit(+) progenitors to the ischemic area, resulting in an increased blood perfusion ratio. Histological analysis suggested that GFP(+) progenitors mobilized from bone marrow, integrated into blood vessels, and differentiated into VEGFR(+) cells. In addition, TUDCA decreased cellular senescence by reducing levels of p53, p21, and reactive oxygen species and increased nitric oxide. Transplantation of TUDCA-primed senescent EPCs in hind limb ischemia significantly improved blood vessel regeneration, as compared with senescent EPCs. Our results suggested that TUDCA promoted neovascularization by enhancing the mobilization of stem/progenitor cells from bone marrow, their differentiation into EPCs, and their integration with preexisting endothelial cells. Stem Cells 2015;33:792-805. PMID:25407160

Cho, Jin Gu; Lee, Jun Hee; Hong, Shin Hee; Lee, Han Na; Kim, Chul Min; Kim, Seo Yoon; Yoon, Kang Jun; Oh, Bae Jun; Kim, Jae Hyeon; Jung, Seok Yoon; Asahara, Takayuki; Kwon, Sang-Mo; Park, Sang Gyu

2015-03-01

237

Fluid-structure interaction analysis on the effects of vessel material properties on blood flow characteristics in stenosed arteries under axial rotation  

NASA Astrophysics Data System (ADS)

We conducted blood flow analysis, using the Fluid-Structure Interaction (FSI) method, to examine how changes in the material properties of blood vessels affect blood flow characteristics, using the carotid artery as the model vessel. The geometry of the blood vessel included 50% stenosis at the center, and blood was modeled as a non-Newtonian fluid. In order to investigate the effects of vessel material properties, linear elastic models with 0.21 MPa, 0.51 MPa, and 1.25 MPa, which are within the typical elastic modulus range of the carotid artery, were used to simulate the blood vessel, and these were compared with the rigid body model. The difference in blood vessel elasticity caused periodic and transient changes in blood flow. The more elastic the blood vessel becomes, the longer the periods of velocity, pressure, and Wall Shear Stress (WSS) change and the smaller the size of the Fluid Recirculation Zone (FRZ). Also, transient changes in blood flow occurred due to the accumulation of differences in flow caused by vessel wall deformation. This is because a change in the stiffness of the vessel wall causes the vessel's vibration period to change, leading to changes in blood flow.

Cho, Seong Wook; Kim, Seung Wook; Sung, Moon Hyun; Ro, Kyoung Chul; Ryou, Hong Sun

2011-03-01

238

Launch Conditions Might Affect the Formation of Blood Vessel in the Quail Chorioallantoic Membrane  

NASA Technical Reports Server (NTRS)

AS 2 part of the first joint USA-Russian MIR/Shuttle program, fertilized quail eggs were flown on the MIR 18 mission. Post-flight examination indicated impaired survival of both the embryos in space and also of control embryos exposed to vibrational and g-forces simulating the conditions experienced during the launch of Progress 227. We hypothesized that excess mechanical forces and/or other conditions during the launch might cause abnormal development of the blood supply in the chorioallantoic membrane (CAM) leading to the impaired survival of the embryos. The CAM, a highly vascularized extraembryonic organ, provides for the oxygen exchange across the egg shell and is thus pivotal for proper embryonic development. To test our hypothesis, we compared angiogenesis In CAMS of eggs which were either exposed to the vibration and g-force profile simulating the conditions at launch of Progress 227 (synchronous controls), or kept under routine conditions in a laboratory Incubator (laboratory controls). At various time points during Incubation, the eggs were fixed in paraformaldehyde for subsequent dissection. At the time of dissection, the CAM was carefully lifted from the egg shell and examined as whole mounts by bright-field and fluorescent microscopy. The development or the vasculature (angiogenesis) was assessed from the density of blood vessels per viewing field and evaluated by computer aided image analysis. We observed a significant decrease In blood-vessel density in the synchronous controls versus "normal" laboratory controls beginning from day 10 of Incubation. The decrease in vascular density was restricted to the smallest vessels only, suggesting that conditions during the launch and/or during the subsequent Incubation of the eggs may affect the normal progress of angiogenesis in the CAM. Abnormal angiogenesis In the CAM might contribute to the impaired survival of the embryos observed in synchronous controls as well as in space.

Henry, M. K.; Unsworth, B. R.; Sychev, B. R.; Guryeva, T. S.; Dadasheva, O. A.; Piert, S. J.; Lagel, K. E.; Dubrovin, L. C.; Jahns, G. C.; Boda, K.; Sabo, V.; Samet, M. M.; Lelkes, P. I.

1998-01-01

239

Distinct mechanisms of relaxation to bioactive components from chamomile species in porcine isolated blood vessels  

SciTech Connect

German chamomile (Matricaria recutita L.), a widely-used herbal medicine, has been reported to have a wide range of biological effects, including smooth muscle relaxation. The aim of this study was to compare the effects of representative compounds from chamomile (apigenin, luteolin, (?)-?-bisabolol, farnesene, umbelliferone; 330 ?M) on vascular tone using porcine coronary and splenic arteries mounted for isometric tension recording in isolated tissue baths and precontracted with the thromboxane-mimetic U46619. Apigenin, luteolin, and (?)-?-bisabolol produced slow, concentration-dependent relaxations in both the coronary and splenic arteries that were not blocked by inhibition of nitric oxide synthase or potassium channels. Removal of extracellular calcium inhibited the relaxations to all three compounds, and these compounds also inhibited calcium re-addition-evoked contractions, indicating that the relaxation response may be mediated through inhibition of calcium influx. Apigenin and luteolin, but not (?)-?-bisabolol, enhanced the relaxation to the nitric oxide donor sodium nitroprusside, indicating that apigenin and luteolin may act to regulate cyclic GMP levels. Umbelliferone produced a rapid, transient relaxation in the splenic artery, but not the coronary artery, that was inhibited by L-NAME and removal of the endothelium, suggesting an influence on nitric oxide production. Farnesene, at concentrations up to 30 ?M, was without effect in either blood vessel. In conclusion, hydroxylated compounds (apigenin, luteolin and (?)-?-bisabolol) found in chamomile all caused a slow relaxation of isolated blood vessels through an effect on calcium influx. Umbelliferone, on the other hand, produced a rapid, transient relaxation dependent upon release of nitric oxide from the endothelium. - Highlights: Apigenin, luteolin, and (-)-?-bisabolol are present in chamomile. They produced slow, concentration-dependent relaxations in arteries. These relaxations were associated with an inhibition of calcium entry. Farnesene, at concentrations up to 30 ?M, was without effect in either blood vessel. Umbelliferone produced a rapid, transient nitric oxide-dependent relaxation.

Roberts, R.E., E-mail: Richard.roberts@nottingham.ac.uk; Allen, S.; Chang, A.P.Y.; Henderson, H.; Hobson, G.C.; Karania, B.; Morgan, K.N.; Pek, A.S.Y.; Raghvani, K.; Shee, C.Y.; Shikotra, J.; Street, E.; Abbas, Z.; Ellis, K.; Heer, J.K.; Alexander, S.P.H., E-mail: steve.alexander@nottingham.ac.uk

2013-11-01

240

3-D segmentation of retinal blood vessels in spectral-domain OCT volumes of the optic nerve head  

NASA Astrophysics Data System (ADS)

Segmentation of retinal blood vessels can provide important information for detecting and tracking retinal vascular diseases including diabetic retinopathy, arterial hypertension, arteriosclerosis and retinopathy of prematurity (ROP). Many studies on 2-D segmentation of retinal blood vessels from a variety of medical images have been performed. However, 3-D segmentation of retinal blood vessels from spectral-domain optical coherence tomography (OCT) volumes, which is capable of providing geometrically accurate vessel models, to the best of our knowledge, has not been previously studied. The purpose of this study is to develop and evaluate a method that can automatically detect 3-D retinal blood vessels from spectral-domain OCT scans centered on the optic nerve head (ONH). The proposed method utilized a fast multiscale 3-D graph search to segment retinal surfaces as well as a triangular mesh-based 3-D graph search to detect retinal blood vessels. An experiment on 30 ONH-centered OCT scans (15 right eye scans and 15 left eye scans) from 15 subjects was performed, and the mean unsigned error in 3-D of the computer segmentations compared with the independent standard obtained from a retinal specialist was 3.4 +/- 2.5 voxels (0.10 +/- 0.07 mm).

Lee, Kyungmoo; Abrmoff, Michael D.; Niemeijer, Meindert; Garvin, Mona K.; Sonka, Milan

2010-03-01

241

Limitations of quantitative photoacoustic measurements of blood oxygenation in small vessels.  

PubMed

We investigate the feasibility of obtaining accurate quantitative information, such as local blood oxygenation level (sO2), with a spatial resolution of about 50 microm from spectral photoacoustic (PA) measurements. The optical wavelength dependence of the peak values of the PA signals is utilized to obtain the local blood oxygenation level. In our in vitro experimental models, the PA signal amplitude is found to be linearly proportional to the blood optical absorption coefficient when using ultrasonic transducers with central frequencies high enough such that the ultrasonic wavelengths are shorter than the light penetration depth into the blood vessels. For an optical wavelength in the 578-596 nm region, with a transducer central frequency that is above 25 MHz, the sensitivity and accuracy of sO2 inversion is shown to be better than 4%. The effect of the transducer focal position on the accuracy of quantifying blood oxygenation is found to be negligible. In vivo oxygenation measurements of rat skin microvasculature yield results consistent with those from in vitro studies, although factors specific to in vivo measurements, such as the spectral dependence of tissue optical attenuation, dramatically affect the accuracy of sO2 quantification in vivo. PMID:17301459

Sivaramakrishnan, Mathangi; Maslov, Konstantin; Zhang, Hao F; Stoica, George; Wang, Lihong V

2007-03-01

242

A Pulsatile Flow Phantom for Image-Guided HIFU Hemostasis of Blood Vessels  

SciTech Connect

A pulsatile flow phantom for studying ultrasound image-guided acoustic hemostasis in a controlled environment has been developed. An ex vivo porcine carotid artery was attached to the phantom and embedded in a visually and ultrasonically transparent gel. Heparinized porcine blood was pumped through the phantom. Power-Doppler and B-mode ultrasound were used to remotely target the HIFU focus to the site of a needle puncture. In nine trials, complete hemostasis was achieved after an average HIFU application of 55 +/- 34 seconds. The vessels remained patent after treatment. With this phantom, it will be possible to do controlled studies of ultrasound image-guided acoustic hemostasis.

Greaby, Robyn; Vaezy, Shahram [Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, Seattle, WA 98195 (United States); Department of Bioengineering, University of Washington, Seattle, WA 98195 (United States)

2005-03-28

243

Ex vivo expansion of hematopoietic stem cells derived from umbilical cord blood in rotating wall vessel  

Microsoft Academic Search

Expansion of umbilical cord blood mononuclear cells (UCB MNCs) was carried out in a rotating wall vessel (RWV) bioreactor and tissue culture flasks (T-flasks) in serum-containing medium supplemented with relatively low doses of purified recombinant human cytokines (5.33ng\\/ml IL-3, 16ng\\/ml SCF, 3.33ng\\/ml G-CSF, 2.13ng\\/ml GM-CSF, 7.47ng\\/ml FL and 7.47ng\\/ml TPO) for 8 days. The cell density, pH and osmolality of

Yang Liu; Tianqing Liu; Xiubo Fan; Xuehu Ma; Zhanfeng Cui

2006-01-01

244

Blood vessels and the occurrence of arteriovenous anastomoses in cephalic heat loss areas of mallards, Anas platyrhynchos (Aves)  

Microsoft Academic Search

1. The blood supply to cephalic heat loss areas (nasal and oropharyngeal mucosa, bill, eyelids) was studied in mallards by using plastic corrosion casts. The structure and organization of the blood vessels, as well as the occurrence of arteriovenous anastomoses (AVAs), were examined by scanning electron microscopy of vascular casts and by paraffin sections.

Uffe Midtgrd

1984-01-01

245

[Comparative morphofunctional characteristics of arterial blood vessels of the different kidney segments in humans].  

PubMed

The arterial blood vessels of 26 kidneys of people of both sexes at the first period of mature age were studied. Using Doppler renal investigation of superior segmental and anterior inferior segmental arteries in color duplex scan mode and multislice computed tomographic angiography, intravital investigation of 20 kidneys were performed. Corrosion casts of the renal vasculature of 6 kidneys, obtained at autopsy, were studied using scanning electron microscopy. It was shown that in kidneys with a single renal artery, anterior inferior and superior segments have a similar level of blood supply--when quantitative parameters of hemodynamics of these renal segments were compared, no significant differences were detected; in fact, no differences were found in the angioarchitectonics of anterior inferior and superior segments. In both segments, initial signs of age involution were found in the form of appearance of individual deformed glomeruli and some rarefaction of capillary network in the renal medulla. PMID:19563176

Dgebuadze, M A; Kordzaua, D D; Gachechiladze, D G; Daneliia, Z A

2009-01-01

246

Targeted drug delivery to flow-obstructed blood vessels using mechanically activated nanotherapeutics.  

PubMed

Obstruction of normal blood flow, which occurs in a variety of diseases, including thromboembolism in stroke and atherosclerosis, is a leading cause of death and long-term adult disability in the Western world. This review focuses on a novel nanotherapeutic drug-delivery platform that is mechanically activated within blood vessels by high-fluid shear stresses to selectively target drugs to sites of vascular obstruction. In vitro and in vivo studies have shown that this approach can be used to efficiently lyse clots using a significantly lower amount of thrombolytic drug than is required when administered in a soluble formulation. This nanotherapeutic strategy can potentially improve both the efficacy and safety of thrombolytic drugs, particularly in patients who are at high risk for brain hemorrhage, and thus provide a new approach for the treatment of many life-threatening and debilitating vascular disorders. PMID:25365638

Korin, Netanel; Gounis, Matthew J; Wakhloo, Ajay K; Ingber, Donald E

2015-01-01

247

A parallel two-level method for simulating blood flows in branching arteries with the resistive boundary condition q  

E-print Network

A parallel two-level method for simulating blood flows in branching arteries with the resistive modeling of blood flows in the arteries is an important and very challenging problem. In order to understand, computationally, the sophisticated hemodynamics in the arteries, it is essential to couple

Cai, Xiao-Chuan

248

Changes in Gene Expression of Pial Vessels of the Blood Brain Barrier during Murine Neurocysticercosis  

PubMed Central

In murine neurocysticercosis (NCC), caused by infection with the parasite Mesocestoides corti, the breakdown of the Blood Brain Barrier (BBB) and associated leukocyte infiltration into the CNS is dependent on the anatomical location and type of vascular bed. Prior studies of NCC show that the BBB comprised of pial vessels are most affected in comparison to the BBB associated with the vasculature of other compartments, particularly parenchymal vessels. Herein, we describe a comprehensive study to characterize infection-induced changes in the genome wide gene expression of pial vessels using laser capture microdissection microscopy (LCM) combined with microarray analyses. Of the 380 genes that were found to be affected, 285 were upregulated and 95 were downregulated. Ingenuity Pathway Analysis (IPA) software was then used to assess the biological significance of differentially expressed genes. The most significantly affected networks of genes were inflammatory response, cell-to-cell signaling and interaction, cellular movement, cellular movement, hematological system development and function, immune cell trafficking, and antimicrobial response, cell-to-cell signaling and interaction embryonic development. RT-PCR analyses validated the pattern of gene expression obtained from microarray analysis. In addition, chemokines CCL5 and CCL9 were confirmed at the protein level by immunofluorescence (IF) microscopy. Our data show altered gene expression related to immune and physiological functions and collectively provide insight into changes in BBB disruption and associated leukocyte infiltration during murine NCC. PMID:23516647

Mishra, Pramod Kumar; Teale, Judy M.

2013-01-01

249

Cerebral blood flow quantification using vessel-encoded arterial spin labeling  

PubMed Central

Arterial spin labeling (ASL) techniques are gaining popularity for visualizing and quantifying cerebral blood flow (CBF) in a range of patient groups. However, most ASL methods lack vessel-selective information, which is important for the assessment of collateral flow and the arterial supply to lesions. In this study, we explored the use of vessel-encoded pseudocontinuous ASL (VEPCASL) with multiple postlabeling delays to obtain individual quantitative CBF and bolus arrival time maps for each of the four main brain-feeding arteries and compared the results against those obtained with conventional pseudocontinuous ASL (PCASL) using matched scan time. Simulations showed that PCASL systematically underestimated CBF by up to 37% in voxels supplied by two arteries, whereas VEPCASL maintained CBF accuracy since each vascular component is treated separately. Experimental results in healthy volunteers showed that there is no systematic bias in the CBF estimates produced by VEPCASL and that the signal-to-noise ratio of the two techniques is comparable. Although more complex acquisition and image processing is required and the potential for motion sensitivity is increased, VEPCASL provides comparable data to PCASL but with the added benefit of vessel-selective information. This could lead to more accurate CBF estimates in patients with a significant collateral flow. PMID:23921895

Okell, Thomas W; Chappell, Michael A; Kelly, Michael E; Jezzard, Peter

2013-01-01

250

Effect of physical variables on capture of magnetic nanoparticles in simulated blood vessels  

NASA Astrophysics Data System (ADS)

This study investigated how the percent capture of magnetic nanoparticles in a simulated vessel varies with physical variables. Magnetic nanoparticles (MNPs) can used as part of therapeutic or diagnostic materials for cancer patients. By capturing these devices with a magnetic field, the particles can be concentrated in an area of diseased tissue. In this study, flow of nanoparticles in simulated blood vessels was used to determine the affect of applying an external magnetic field. This study used maghemite nanoparticles as the MNPs and either water or Fetal Bovine Serum as the carrier fluid. A UV-Vis collected capture data. The percent capture of MNPs was positively influenced by five physical variables: larger vessel diameters, lower linear flow velocity, higher magnetic field strength, better dispersion, lower MNP concentration, and lower protein content in fluid. Free MNPs were also compared to micelles, with the free particles having more successful magnetic capture. Four factors contributed to these trends: the strength of the magnetic field's influence on the MNPs, the MNPs' interactions with other particles and the fluid, the momentum of the nanoparticles, and magnetic mass to total mass ratio of the flowing particles.

Zhang, Minghui; Brazel, Christopher

2011-11-01

251

Differentiation of smooth muscle progenitor cells in peripheral blood and its application in tissue engineered blood vessels*  

PubMed Central

Background: A major shortcoming in tissue engineered blood vessels (TEBVs) is the lack of healthy and easily attainable smooth muscle cells (SMCs). Smooth muscle progenitor cells (SPCs), especially from peripheral blood, may offer an alternative cell source for tissue engineering involving a less invasive harvesting technique. Methods: SPCs were isolated from 5-ml fresh rat peripheral blood by density-gradient centrifugation and cultured for 3 weeks in endothelial growth medium-2-MV (EGM-2-MV) medium containing platelet-derived growth factor-BB (PDGF BB). Before seeded on the synthesized scaffold, SPC-derived smooth muscle outgrowth cell (SOC) phenotypes were assessed by immuno-fluorescent staining, Western blot analysis, and reverse transcription polymerase chain reaction (RT-PCR). The cells were seeded onto the silk fibroin-modified poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (SF-PHBHHx) scaffolds by 6104 cells/cm2 and cultured under the static condition for 3 weeks. The growth and proliferation of the seeded cells on the scaffold were analyzed by 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide (MTT) assay, scanning electron microscope (SEM), and 4,6-diamidino-2-phenylindole (DAPI) staining. Results: SOCs displayed specific hill and valley morphology, expressed the specific markers of the SMC lineage: smooth muscle (SM) ?-actin, calponin and smooth muscle myosin heavy chain (SM MHC) at protein and messenger ribonucleic acid (mRNA) levels. RT-PCR results demonstrate that SOCs also expressed smooth muscle protein 22? (SM22?), a contractile protein, and extracellular matrix components elastin and matrix Gla protein (MGP), as well as vascular endothelial growth factor (VEGF). After seeded on the SF-PHBHHx scaffold, the cells showed excellent metabolic activity and proliferation. Conclusion: SPCs isolated from peripheral blood can be differentiated into the SMCs in vitro and have an impressive growth potential in the biodegradable synthesized scaffold. Thus, SPCs may be a promising cell source for constructing TEBVs. PMID:19067459

Xie, Shang-zhe; Fang, Ning-tao; Liu, Shui; Zhou, Ping; Zhang, Yi; Wang, Song-mei; Gao, Hong-yang; Pan, Luan-feng

2008-01-01

252

Enhanced tissue strength in cryopreserved, collagen-based blood vessel constructs.  

PubMed

Traditional cryopreservation methods do not adequately preserve complex natural or engineered multicellular tissues due to the ice formation in the extracellular matrices. Vitrification is an alternate ice-free method for cryopreservation. This study compares the effects of vitrification and conventional cryopreservation on an engineered blood vessel construct. Collagen-based vascular constructs were used as models in this study. Tubular constructs were cut into rings and distributed into fresh, frozen, and vitrified groups for evaluation of mechanical properties and cell viability. Passive mechanical tests revealed enhanced tissue strength after both freezing and vitrification. Cryosubstitution studies of frozen and vitrified constructs revealed negligible ice in the vitrified specimens and extensive ice formation in the extracellular matrix of frozen specimens. Morphological changes associated with ice formation were visible within tissues preserved using traditional cryopreservation but not in tissue preserved using vitrification. The metabolic assay results indicated that vitrified tissue had similar viability to fresh controls. These results suggest that the increased tissue strength after cryopreservation may relate to thermal property change during preservation that cross-link collagen in tissue-engineered blood vessels. Further development of this cryopreservation method is necessary to minimize the alteration in material property and maintain cell viability of the constructs. PMID:16387185

Elder, E; Chen, Z; Ensley, A; Nerem, R; Brockbank, K; Song, Y

2005-12-01

253

The Effects of Impact Vibration on Peripheral Blood Vessels and Nerves  

PubMed Central

Research regarding the risk of developing hand-arm vibration syndrome after exposure to impact vibration has produced conflicting results. This study used an established animal model of vibration-induced dysfunction to determine how exposure to impact vibration affects peripheral blood vessels and nerves. The tails of male rats were exposed to a single bout of impact vibration (15 min exposure, at a dominant frequency of 30?Hz and an unweighted acceleration of approximately 345 m/s2) generated by a riveting hammer. Responsiveness of the ventral tail artery to adrenoreceptor-mediated vasoconstriction and acetylcholine-mediated re-dilation was measured ex vivo. Ventral tail nerves and nerve endings in the skin were assessed using morphological and immunohistochemical techniques. Impact vibration did not alter vascular responsiveness to any factors or affect trunk nerves. However, 4 days following exposure there was an increase in protein-gene product (PGP) 9.5 staining around hair follicles. A single exposure to impact vibration, with the exposure characteristics described above, affects peripheral nerves but not blood vessels. PMID:24077447

KRAJNAK, Kristine M.; WAUGH, Stacey; JOHNSON, Claud; MILLER, G. Roger; XU, Xueyan; WARREN, Christopher; DONG, Ren G.

2013-01-01

254

Isolation of blood-vessel-derived multipotent precursors from human skeletal muscle.  

PubMed

Since the discovery of mesenchymal stem/stromal cells (MSCs), the native identity and localization of MSCs have been obscured by their retrospective isolation in culture. Recently, using fluorescence-activated cell sorting (FACS), we and other researchers prospectively identified and purified three subpopulations of multipotent precursor cells associated with the vasculature of human skeletal muscle. These three cell populations: myogenic endothelial cells (MECs), pericytes (PCs), and adventitial cells (ACs), are localized respectively to the three structural layers of blood vessels: intima, media, and adventitia. All of these human blood-vessel-derived stem cell (hBVSC) populations not only express classic MSC markers but also possess mesodermal developmental potentials similar to typical MSCs. Previously, MECs, PCs, and ACs have been isolated through distinct protocols and subsequently characterized in separate studies. The current isolation protocol, through modifications to the isolation process and adjustments in the selective cell surface markers, allows us to simultaneously purify all three hBVSC subpopulations by FACS from a single human muscle biopsy. This new method will not only streamline the isolation of multiple BVSC subpopulations but also facilitate future clinical applications of hBVSCs for distinct therapeutic purposes. PMID:25177794

Chen, William C W; Saparov, Arman; Corselli, Mirko; Crisan, Mihaela; Zheng, Bo; Pault, Bruno; Huard, Johnny

2014-01-01

255

Visualisation of human subcutaneous blood vessels by increasing coherence probing depth  

SciTech Connect

An improved Fourier-domain rapid-scanning optical delay in the reference arm of a Michelson interferometer is described which allows the use of a low-power superluminescent diode (down to 0.2 mW) and of a few wavelengths simultaneously. The method of raster scanning and averaging in the sample arm of the interferometer within a pixel provides an additional increase in the signal-to-noise ratio by 4-10 dB and, in combination with optical clearing, an increase in the coherence probing depth for the human skin in vivo up to 1.5-1.6 mm. As a result, subcutaneous blood vessels are visualised for the first time and a signal from the bloodstream is detected in the transitional regime between reflected and diffusively scattered photons. The images of subcutaneous blood vessels of the human palm and finger in vivo are presented. The possibility of construction of a low-coherence Doppler spectrograph with a variable coherence length is discussed. (laser applications and other topics in quantum electronics)

Proskurin, S G; Wang, R K [Cranfield Health, Cranfield University, Silsoe (United Kingdom)

2004-12-31

256

Infrared Free Electron Laser Induced Angioplasty for Arteriosclerotic Region of Blood Vessels  

NASA Astrophysics Data System (ADS)

In order to estimate the optimum laser conditions for efficient dissociation of cholesterol ester in an arteriosclerotic region of blood vessels, we have investigated the relationship between laser wavelength and power density on cholesterol ester dissociation using a mid infrared free electron laser (MIR-FEL). In this study, cholesteryl oleate, which is a typical cholesterol ester found in arteriosclerotic regions, was irradiated with 5.75-?m-FELs, which cause vibration of ester bonds. Two results were obtained. (1) Ester dissociated depending on the absorption coefficient, and the macropulse duration was shorter than the thermal relaxation time, showing that ester bonds dissociated into carboxylic acid and cholesterol by macropulse-induced thermal effects without accompanying thermal diffusion, (2) Using a wavelength of 5.75 ?m, the maximum ester dissociation ratio was achieved under the optimum laser conditions of a macropulse energy density of 0.4-1.0 J/cm2. We conclude that MIR pulsed-lasers with a wavelength of 5.75 ?m can be useful for removal of cholesteryl ester in an arteriosclerotic region of blood vessels.

Awazu, Kunio; Fukami, Yuko

2004-08-01

257

DSA Image Blood Vessel Skeleton Extraction Based on Anti-concentration Diffusion and Level Set Method  

NASA Astrophysics Data System (ADS)

Serious types of vascular diseases such as carotid stenosis, aneurysm and vascular malformation may lead to brain stroke, which are the third leading cause of death and the number one cause of disability. In the clinical practice of diagnosis and treatment of cerebral vascular diseases, how to do effective detection and description of the vascular structure of two-dimensional angiography sequence image that is blood vessel skeleton extraction has been a difficult study for a long time. This paper mainly discussed two-dimensional image of blood vessel skeleton extraction based on the level set method, first do the preprocessing to the DSA image, namely uses anti-concentration diffusion model for the effective enhancement and uses improved Otsu local threshold segmentation technology based on regional division for the image binarization, then vascular skeleton extraction based on GMM (Group marching method) with fast sweeping theory was actualized. Experiments show that our approach not only improved the time complexity, but also make a good extraction results.

Xu, Jing; Wu, Jian; Feng, Daming; Cui, Zhiming

258

Formation of a Direct Arterial Blood Supply to the Anterior Pituitary Gland following Complete or Partial Interruption of the Hypophyseal Portal Vessels  

Microsoft Academic Search

If regions of the anterior pituitary gland received systemic blood via a direct arterial blood supply these regions would escape hypothalamic regulation and thus be a sequela in endocrine disorders. Since, in the untreated rat, all of the blood supply to the anterior pituitary gland is via the hypophyseal portal vessels, we hypothesized that partial interruption of the portal vessels

Florianne Monnet; Kathleen A. Elias; Katherine Fagin; Anne Neill; Paul Goldsmith; Richard I. Weiner

1984-01-01

259

Laser Doppler measurements of inner ear blood flow during experimental thrombosis of cochlear blood vessels in the guinea pig.  

PubMed

This study investigated the vascular effect of ferromagnetic obstruction of cochlear blood vessels in the guinea pig using dual-channel laser Doppler flowmetry. To improve this technique, we tested new types of magnets and iron spheres. In so doing, the cochlear temperature was lowered selectively and general hypothermia was avoided. The success of vascular impairment in the inner ear was found to depend on the experimental conditions used. Given normothermic conditions (38 degrees C body temperature), a clear reduction in cochlear blood flow (CBF) was found in only about 30% of the animals tested when an aluminium-nickel-cobalt alloy magnet and carbonyl iron spheres were used, while this ratio increased to about 80% under general hypothermia (33 degrees C). Using a stronger neodymium-iron-boron magnet and smaller-sized iron spheres, we found the success of vascular obstruction to be approximately 70% under normothermia and 100% with local hypothermia (to 33 degrees C) of the cochlea. Although the extent of vascular impairment revealed a considerable interindividual variation, the present findings demonstrate that ferromagnetic intervention in CBF with dual-channel laser Doppler flowmetry can be used to investigate the effect of quantified cochlear ischemia on inner ear physiology in the guinea pig model and test various therapeutic strategies. PMID:9065662

Scheibe, F; Haupt, H; Grunert, H

1997-01-01

260

The receptor tyrosine kinase inhibitor SU11248 impedes endothelial cell migration, tubule formation, and blood vessel formation in vivo, but has little effect on existing tumor vessels.  

PubMed

Antiangiogenic agents produce regression in few tumors in clinical trials, but are effective in preventing recurrences. To determine whether the vascular endothelial growth factor (VEGF) receptor is a molecular target to prevent metastatic disease, we utilized a non-specific inhibitor of the VEGF receptor, SU11248. This receptor tyrosine kinase (RTK) inhibitor prevented migration of endothelial cells and markedly attenuated capillary-like tubule formation in endothelial cells in culture. Similarly, this agent prevented blood vessel formation in the tumor vascular window model. VEGF RTK inhibition produced minimal effects on established blood vessels in the tumor vascular window model and little effect on blood flow studied by power Doppler analysis. To determine whether these agents attenuate the development of metastases, Lewis lung carcinoma tumors were resected from the dorsal skin and lung metastases were quantified with and without treatment with SU11248. The RTK inhibitor attenuated the formation of lung metastases following resection of the hind limb tumor. In contrast, these agents did not induce regression of primaries but slowed the progression of tumor growth. These findings suggest that the greatest role for VEGF antagonists may be to prevent the formation of new blood vessels, during and after conventional therapy is given to existing neoplastic disease. PMID:15609077

Osusky, Katherine L; Hallahan, Dennis E; Fu, Allie; Ye, Fei; Shyr, Yu; Geng, Ling

2004-01-01

261

Responses of bone and joint blood vessels in cats and rabbits to electrical stimulation of nerves supplying the knee.  

PubMed Central

1. Experiments were performed to assess the extent to which knee joint blood flow in cats and rabbits is affected by electrical stimulation of the nerve supply to the knee. 2. Absolute changes in blood flow were measured using the radiolabelled microsphere (approximately 15 microns) technique whilst relative changes in blood flow were assessed using laser Doppler flowmetry. 3. Despite deep general anaesthesia, sympathetic nerve fibres innervating cat knee joint blood vessels showed marked 'tone'. 4. Blood flow to the joint capsule (synovium and overlying fibrous and areolar tissues) was substantially reduced (by approximately 90% in the cat and approximately 45% in the rabbit) during electrical stimulation of the articular nerve supply. 5. The percentage change in the laser Doppler flowmeter signal did not differ significantly from the percentage change in blood flow measured by microsphere technique. 6. Blood vessels in the cancellous bone of the distal femur (condyles) and proximal tibia (plateau) appear to be innervated by vasoconstrictor fibres which reach their effectors via the articular nerves. However, the cortical bone and red marrow of the diaphysis of the femur do not receive such innervation. 7. The potency of the vasoconstrictor influences acting on joint blood vessels could be of relevance in the pathogenesis of inflammatory joint diseases. PMID:2100317

Ferrell, W R; Khoshbaten, A; Angerson, W J

1990-01-01

262

Contrasting Actions of Selective Inhibitors of Angiopoietin-1 and Angiopoietin-2 on the Normalization of Tumor Blood Vessels  

PubMed Central

Angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2) have complex actions in angiogenesis and vascular remodeling due to their effects on Tie2 receptor signaling. Ang2 blocks Ang1-mediated activation of Tie2 in endothelial cells under certain conditions but is a Tie2 receptor agonist in others. We examined the effects of selective inhibitors of Ang1 (mL4-3) or Ang2 (L1-7[N]), alone or in combination, on the vasculature of human Colo205 tumors in mice. The Ang2 inhibitor decreased the overall abundance of tumor blood vessels by reducing tumor growth and keeping vascular density constant. After inhibition of Ang2, tumor vessels had many features of normal blood vessels (normalization), as evidenced by junctional accumulation of vascular endothelial-cadherin, junctional adhesion molecule-A, and platelet/endothelial cell adhesion molecule-1 in endothelial cells, increased pericyte coverage, reduced endothelial sprouting, and remodeling into smaller, more uniform vessels. The Ang1 inhibitor by itself had little noticeable effect on the tumor vasculature. However, when administered with the Ang2 inhibitor, the Ang1 inhibitor prevented tumor vessel normalization, but not the reduction in tumor vascularity produced by the Ang2 inhibitor. These findings are consistent with a model whereby inhibition of Ang2 leads to normalization of tumor blood vessels by permitting the unopposed action of Ang1, but decreases tumor vascularity primarily by blocking Ang2 actions. PMID:19815705

Falcn, Beverly L.; Hashizume, Hiroya; Koumoutsakos, Petros; Chou, Jeyling; Bready, James V.; Coxon, Angela; Oliner, Jonathan D.; McDonald, Donald M.

2009-01-01

263

Detection of Trypanosoma brucei spp. in human blood by a nonradioactive branched DNA-based technique.  

PubMed Central

We have developed a nonradioactive branched DNA (bDNA)-based assay for the diagnosis of the African trypanosomiases in simple buffy coat preparations of human blood. Two repetitive DNA sequences specific to the Trypanosoma brucei complex were chosen as targets of the bDNA assay, a technique which amplifies the signal from a target molecule rather than the target itself. Comparable sensitivities were observed with cloned target sequences, purified T. brucei DNA, procyclic trypanosomes, and bloodstream trypomastigotes. The results of bDNA analysis of human blood samples from Cte d'Ivoire (n = 50) showed excellent agreement with those of buffy coat microscopy. The bDNA technology offers certain advantages over alternative molecular biological techniques, including the simplicity of sample preparation and of the procedure itself, the stability of the reagents, the ability to process large numbers of samples simultaneously, and freedom from crosscontamination artifacts. We have successfully applied the bDNA technique to the detection of T. brucei in clinical samples from regions where T. brucei infection is endemic; to our knowledge, this is the first report of the molecular detection of T. brucei in human blood. PMID:8880488

Harris, E; Detmer, J; Dungan, J; Doua, F; White, T; Kolberg, J A; Urdea, M S; Agabian, N

1996-01-01

264

Detection of Trypanosoma brucei spp. in human blood by a nonradioactive branched DNA-based technique.  

PubMed

We have developed a nonradioactive branched DNA (bDNA)-based assay for the diagnosis of the African trypanosomiases in simple buffy coat preparations of human blood. Two repetitive DNA sequences specific to the Trypanosoma brucei complex were chosen as targets of the bDNA assay, a technique which amplifies the signal from a target molecule rather than the target itself. Comparable sensitivities were observed with cloned target sequences, purified T. brucei DNA, procyclic trypanosomes, and bloodstream trypomastigotes. The results of bDNA analysis of human blood samples from Cte d'Ivoire (n = 50) showed excellent agreement with those of buffy coat microscopy. The bDNA technology offers certain advantages over alternative molecular biological techniques, including the simplicity of sample preparation and of the procedure itself, the stability of the reagents, the ability to process large numbers of samples simultaneously, and freedom from crosscontamination artifacts. We have successfully applied the bDNA technique to the detection of T. brucei in clinical samples from regions where T. brucei infection is endemic; to our knowledge, this is the first report of the molecular detection of T. brucei in human blood. PMID:8880488

Harris, E; Detmer, J; Dungan, J; Doua, F; White, T; Kolberg, J A; Urdea, M S; Agabian, N

1996-10-01

265

Tumor blood vessel "normalization" improves the therapeutic efficacy of boron neutron capture therapy (BNCT) in experimental oral cancer  

SciTech Connect

We previously demonstrated the efficacy of BNCT mediated by boronophenylalanine (BPA) to treat tumors in a hamster cheek pouch model of oral cancer with no normal tissue radiotoxicity and moderate, albeit reversible, mucositis in precancerous tissue around treated tumors. It is known that boron targeting of the largest possible proportion of tumor cells contributes to the success of BNCT and that tumor blood vessel normalization improves drug delivery to the tumor. Within this context, the aim of the present study was to evaluate the effect of blood vessel normalization on the therapeutic efficacy and potential radiotoxicity of BNCT in the hamster cheek pouch model of oral cancer.

D. W. Nigg

2012-01-01

266

The Behaviors of Ferro-Magnetic Nano-Particles In and Around Blood Vessels under Applied Magnetic Fields  

PubMed Central

In magnetic drug delivery, therapeutic magnetizable particles are typically injected into the blood stream and magnets are then used to concentrate them to disease locations. The behavior of such particles in-vivo is complex and is governed by blood convection, diffusion (in blood and in tissue), extravasation, and the applied magnetic fields. Using physical first-principles and a sophisticated vessel-membrane-tissue (VMT) numerical solver, we comprehensively analyze in detail the behavior of magnetic particles in blood vessels and surrounding tissue. For any blood vessel (of any size, depth, and blood velocity) and tissue properties, particle size and applied magnetic fields, we consider a Krogh tissue cylinder geometry and solve for the resulting spatial distribution of particles. We find that there are three prototypical behaviors (blood velocity dominated, magnetic force dominated, and boundary-layer formation) and that the type of behavior observed is uniquely determined by three non-dimensional numbers (the magnetic-Richardson number, mass Pclet number, and Renkin reduced diffusion coefficient). Plots and equations are provided to easily read out which behavior is found under which circumstances (Figures 5, 6, 7, and 8). We compare our results to previously published in-vitro and in-vivo magnetic drug delivery experiments. Not only do we find excellent agreement between our predictions and prior experimental observations, but we are also able to qualitatively and quantitatively explain behavior that was previously not understood. PMID:21278859

Nacev, A.; Beni, C.; Bruno, O.; Shapiro, B.

2010-01-01

267

Low level arsenic promotes progressive inflammatory angiogenesis and liver blood vessel remodeling in mice  

SciTech Connect

The vascular effects of arsenic in drinking water are global health concerns contributing to human disease worldwide. Arsenic targets the endothelial cells lining blood vessels, and endothelial cell activation or dysfunction may underlie the pathogenesis of both arsenic-induced vascular diseases and arsenic-enhanced tumorigenesis. The purpose of the current studies was to demonstrate that exposing mice to drinking water containing environmentally relevant levels of arsenic promoted endothelial cell dysfunction and pathologic vascular remodeling. Increased angiogenesis, neovascularization, and inflammatory cell infiltration were observed in Matrigel plugs implanted in C57BL/6 mice following 5-week exposures to 5-500 ppb arsenic [Soucy, N.V., Mayka, D., Klei, L.R., Nemec, A.A., Bauer, J.A., Barchowsky, A., 2005. Neovascularization and angiogenic gene expression following chronic arsenic exposure in mice. Cardiovasc.Toxicol 5, 29-42]. Therefore, functional in vivo effects of arsenic on endothelial cell function and vessel remodeling in an endogenous vascular bed were investigated in the liver. Liver sinusoidal endothelial cells (LSEC) became progressively defenestrated and underwent capillarization to decrease vessel porosity following exposure to 250 ppb arsenic for 2 weeks. Sinusoidal expression of PECAM-1 and laminin-1 proteins, a hallmark of capillarization, was also increased by 2 weeks of exposure. LSEC caveolin-1 protein and caveolae expression were induced after 2 weeks of exposure indicating a compensatory change. Likewise, CD45/CD68-positive inflammatory cells did not accumulate in the livers until after LSEC porosity was decreased, indicating that inflammation is a consequence and not a cause of the arsenic-induced LSEC phenotype. The data demonstrate that the liver vasculature is an early target of pathogenic arsenic effects and that the mouse liver vasculature is a sensitive model for investigating vascular health effects of arsenic.

Straub, Adam C. [Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, PA 15219 (United States); Stolz, Donna B. [Department of Cell Biology, University of Pittsburgh School of Medicine, PA 15219 (United States); Vin, Harina [Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, PA 15219 (United States); Department of Cell Biology, University of Pittsburgh School of Medicine, PA 15219 (United States); Ross, Mark A. [Department of Cell Biology, University of Pittsburgh School of Medicine, PA 15219 (United States); Soucy, Nicole V. [Department of Pharmacology and Toxicology, Dartmouth Medical School (United States); Klei, Linda R. [Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, PA 15219 (United States); Barchowsky, Aaron [Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, PA 15219 (United States)], E-mail: aab20@pitt.edu

2007-08-01

268

Smooth Muscle and Other Cell Sources for Human Blood Vessel Engineering  

PubMed Central

Despite substantial progress in the field of vascular tissue engineering over the past decades, transition to human models has been rather challenging. The limited replicative life spans of human adult vascular cells, and their slow rate of collagenous matrix production in vitro, have posed important hurdles in the development of mechanically robust and biologically functional engineered grafts. With the more recent advances in the field of stem cells, investigators now have access to a plethora of new cell source alternatives for vascular engineering. In this paper, we review various alternative cell sources made available more recently for blood vessel engineering and also present some recent data on the derivation of smooth muscle cells from human induced pluripotent stem cells. PMID:22041291

Sundaram, Sumati; Niklason, Laura E.

2011-01-01

269

An enhanced segmentation of blood vessels in retinal images using contourlet.  

PubMed

Retinal images acquired using a fundus camera often contain low grey, low level contrast and are of low dynamic range. This may seriously affect the automatic segmentation stage and subsequent results; hence, it is necessary to carry-out preprocessing to improve image contrast results before segmentation. Here we present a new multi-scale method for retinal image contrast enhancement using Contourlet transform. In this paper, a combination of feature extraction approach which utilizes Local Binary Pattern (LBP), morphological method and spatial image processing is proposed for segmenting the retinal blood vessels in optic fundus images. Furthermore, performance of Adaptive Neuro-Fuzzy Inference System (ANFIS) and Multilayer Perceptron (MLP) is investigated in the classification section. The performance of the proposed algorithm is tested on the publicly available DRIVE database. The results are numerically assessed for different proposed algorithms. PMID:19163470

Rezatofighi, S H; Roodaki, A; Ahmadi Noubari, H

2008-01-01

270

NOTE: An equation describing spread of membrane potential changes in a short segment of blood vessel  

NASA Astrophysics Data System (ADS)

The spread of membrane potential changes throughout certain cells and tissues plays an important role in their physiology. The attenuation of such changes in any tissue is usually characterized by the cable length constant lambda, which can be determined experimentally if the equations describing membrane potential spread in the tissue are known. Here we derive an equation describing spread of membrane potential changes in a short cable, which is an appropriate model for short segments of blood vessels. This equation is more general than those already published in that the positions of both the current source that gives rise to a potential change, and the point at which the change is measured, can be anywhere along the cable.

Crane, G. J.; Neild, T. O.

1999-10-01

271

Radiation-guided drug delivery to tumor blood vessels results in improved tumor growth delay.  

PubMed

Tumor blood vessels are biological targets for cancer therapy. In this study, a tumor vasculature targeting system that consisted of liposomes and lectin (WGA) was built. Liposomes were used to carry a number of liposome-friendly anti-tumoral agents along with WGA, a lectin which posseses a specific affinity for binding to inflamed endothelial cells. In order to target tumor vasculature, inflammation of endothelial cells was induced by radiation. Because ionizing radiation induces an inflammatory response in tumor vasculature, lectin-conjugates were utilized to determine whether radiation can be used to target drug delivery to tumor vessels. Wheat germ agglutinin (WGA) is one such lectin that binds to inflamed microvasculature. WGA was conjugated to liposomes containing cisplatin and administered to tumor bearing mice. Tumor growth delay was used to analyze the efficacy of cytotoxicity. FITC-conjugated WGA accumulated within irradiated tumor microvasculature. WGA was conjugated to liposomes and labeled with 111In. This demonstrated radiation-inducible tumor-selective binding. WGA-liposome-conjugates were loaded with Cisplatin and administered to mice bearing irradiated tumors. Tumors treated with a combination of liposome encapsulated cisplatin together with radiation showed a significant increase in tumor growth delay as compared to radiation alone. These findings demonstrate that ionizing radiation can be used to guide drug delivery to tumor microvasculature. PMID:15451595

Geng, Ling; Osusky, Katherine; Konjeti, Sekhar; Fu, Allie; Hallahan, Dennis

2004-10-19

272

Degradation profile and preliminary clinical testing of a resorbable device for ligation of blood vessels.  

PubMed

A resorbable device for ligation of blood vessels was developed and tested in vitro to reveal the degradation profile of the device and to predict the clinical performance in terms of adequate mechanical support during a healing period of 1week. In addition, preliminary clinical testing was performed that showed complete hemostasis and good tissue grip of renal arteries in five pigs. The device was made by injection molding of poly(glycolide-co-trimethylene carbonate) triblock copolymer, and it consisted of a case with a locking mechanism connected to a partly perforated flexible band. A hydrolytic degradation study was carried out for 7, 30 and 60days in water and buffer medium, following the changes in mass, water absorption, pH and mechanical properties. A new rapid matrix-free laser desorption ionization-mass spectrometry (LDI-MS) method was developed for direct screening of degradation products released into the degradation medium. The combination of LDI-MS and electrospray ionization-mass spectrometry analyses enabled the comparison of the degradation product patterns in water and buffer medium. The identified degradation products were rich in trimethylene carbonate units, indicating preferential hydrolysis of amorphous regions where trimethylene units are located. The crystallinity of the material was doubled after 60days of hydrolysis, additionally confirming the preferential hydrolysis of trimethylene carbonate units and the enrichment of glycolide units in the remaining solid matrix. The mechanical performance of the perforated band was followed for the first week of hydrolysis and the results suggest that sufficient strength is retained during the healing time of the blood vessels. PMID:23438863

Aminlashgari, Nina; Hglund, Odd V; Borg, Niklas; Hakkarainen, Minna

2013-06-01

273

Electrospun Polycaprolactone Scaffolds for Small-Diameter Tissue Engineered Blood Vessels  

NASA Astrophysics Data System (ADS)

Cardiovascular disease is the leading cause of death in the United States with many patients requiring coronary artery bypass grafting. The current standard is using autografts such as the saphenous vein or intimal mammary artery, however creating a synthetic graft could eliminate this painful and inconvenient procedure. Large diameter grafts have long been established with materials such as DacronRTM and TeflonRTM, however these materials have not proved successful in small-diameter (< 6 mm) grafts where thrombosis and intimal hyperplasia are common in graft failure. With the use of a synthetic biodegradable polymer (polycaprolactone) we utilize our expertise in electrospinning and femtosecond laser ablation to create a novel tri-layered tissue engineered blood vessel containing microchannels. The benefits of creating a tri-layer is to mimic native arteries that contain an endothelium to prevent thrombosis in the inner layer, aligned smooth muscle cells in the middle to control vasodilation and constriction, and a mechanically robust outer layer. The following work evaluates the mechanical properties of such a graft (tensile, fatigue, burst pressure, and suture retention strength), the ability to rapidly align cells in laser ablated microchannels in PCL scaffolds, and the biological integration (co-culture of endothelial and smooth muscle cells) with electrospun PCL scaffolds. The conclusions from this work establish that the electrospun tri-layers provide adequate mechanical strength as a tissue engineered blood vessel, that laser ablated microchannels are able to contain the smooth muscle cells, and that cells are able to adhere to PCL fibers. However, future work includes adjusting microchannel dimensions to properly align smooth muscle cells along with perfect co-cultures of endothelial and smooth muscle cells on the electrospun tri-layer.

Lee, Carol Hsiu-Yueh

274

Three-dimensional multi-scale model of deformable platelets adhesion to vessel wall in blood flow  

PubMed Central

When a blood vessel ruptures or gets inflamed, the human body responds by rapidly forming a clot to restrict the loss of blood. Platelets aggregation at the injury site of the blood vessel occurring via plateletplatelet adhesion, tethering and rolling on the injured endothelium is a critical initial step in blood clot formation. A novel three-dimensional multi-scale model is introduced and used in this paper to simulate receptor-mediated adhesion of deformable platelets at the site of vascular injury under different shear rates of blood flow. The novelty of the model is based on a new approach of coupling submodels at three biological scales crucial for the early clot formation: novel hybrid cell membrane submodel to represent physiological elastic properties of a platelet, stochastic receptorligand binding submodel to describe cell adhesion kinetics and lattice Boltzmann submodel for simulating blood flow. The model implementation on the GPU cluster significantly improved simulation performance. Predictive model simulations revealed that platelet deformation, interactions between platelets in the vicinity of the vessel wall as well as the number of functional GPIb? platelet receptors played significant roles in platelet adhesion to the injury site. Variation of the number of functional GPIb? platelet receptors as well as changes of platelet stiffness can represent effects of specific drugs reducing or enhancing platelet activity. Therefore, predictive simulations can improve the search for new drug targets and help to make treatment of thrombosis patient-specific. PMID:24982253

Wu, Ziheng; Xu, Zhiliang; Kim, Oleg; Alber, Mark

2014-01-01

275

Forces on a Wall-Bound Leukocyte in a Small Vessel Due to Red Cells in the Blood Stream  

PubMed Central

As part of the inflammation response, white blood cells (leukocytes) are well known to bind nearly statically to the vessel walls, where they must resist the force exerted by the flowing blood. This force is particularly difficult to estimate due to the particulate character of blood, especially in small vessels where the red blood cells must substantially deform to pass an adhered leukocyte. An efficient simulation tool with realistically flexible red blood cells is used to estimate these forces. At these length scales, it is found that the red cells significantly augment the streamwise forces that must be resisted by the binding. However, interactions with the red cells are also found to cause an average wall-directed force, which can be anticipated to enhance binding. These forces increase significantly as hematocrit values approach 25% and decrease significantly as the leukocyte is made flatter on the wall. For a tube hematocrit of 25% and a spherical protrusion with a diameter three-quarters that of the vessel, the average forces are increased by ?40% and the local forces are more than double those estimated with an effective-viscosity-homogenized blood. Both the enhanced streamwise and wall-ward forces and their unsteady character are potentially important in regard to binding mechanisms. PMID:23062353

Isfahani, AmirH.G.; Freund, JonathanB.

2012-01-01

276

Aging in blood vessels. Medicinal agents FOR systemic arterial hypertension in the elderly.  

PubMed

Aging impairs blood vessel function and leads to cardiovascular disease. The mechanisms underlying the age-related endothelial, smooth muscle and extracellular matrix vascular dysfunction are discussed. Vascular dysfunction is caused by: (1) Oxidative stress enhancement. (2) Reduction of nitric oxide (NO) bioavailability, by diminished NO synthesis and/or augmented NO scavenging. (3) Production of vasoconstrictor/vasodilator factor imbalances. (4) Low-grade pro-inflammatory environment. (5) Impaired angiogenesis. (6) Endothelial cell senescence. The aging process in vascular smooth muscle is characterized by: (1) Altered replicating potential. (2) Change in cellular phenotype. (3) Changes in responsiveness to contracting and relaxing mediators. (4) Changes in intracellular signaling functions. Systemic arterial hypertension is an age-dependent disorder, and almost half of the elderly human population is hypertensive. The influence of hypertension on the aging cardiovascular system has been studied in models of hypertensive rats. Treatment for hypertension is recommended in the elderly. Lifestyle modifications, natural compounds and hormone therapies are useful for initial stages and as supporting treatment with medication but evidence from clinical trials in this population is needed. Since all antihypertensive agents can lower blood pressure in the elderly, therapy should be based on its potential side effects and drug interactions. PMID:25311590

Rubio-Ruiz, Mara Esther; Prez-Torres, Israel; Soto, Mara Elena; Pasteln, Gustavo; Guarner-Lans, Vernica

2014-11-01

277

Human Blood VesselDerived Endothelial Progenitors for Endothelialization of Small Diameter Vascular Prosthesis  

PubMed Central

Background Coronary bypass graft failure as a result of acute thrombosis and intimal hyperplasia has been the major challenge in surgical procedures involving small-diameter vascular prosthesis. Coating synthetic grafts with patients' own endothelial cells has been suggested to improve the patency rate and overall success of bypass surgeries. Methodology/Principal Findings We isolated endothelial progenitor cells (EPCs) from leftover pieces of human saphenous vein/mammary artery. We demonstrate that EPCs can be expanded to generate millions of cells under low-density culture conditions. Exposure to high-density conditions induces differentiation to endothelial cell phenotype. EPCderived endothelial cells show expression of CD144high, CD31, and vWF. We then assessed the ability of differentiated endothelial cells to adhere and grow on small diameter expanded polytetrafluoroethylene (ePTFE) tubings. Since ePTFE tubings are highly hydrophobic, we optimized protocols to introduce hydrophilic groups on luminal surface of ePTFE tubings. We demonstrate here a stepwise protocol that involves introduction of hydrophilic moieties and coating with defined ECM components that support adhesion of endothelial cells, but not of blood platelets. Conclusion/Significance Our data confirms that endothelial progenitors obtained from adult human blood vessels can be expanded in vitro under xenoprotein-free conditions, for potential use in endothelialization of small diameter ePTFE grafts. These endothelialized grafts may represent a promising treatment strategy for improving the clinical outcome of small-caliber vascular grafts in cardiac bypass surgeries. PMID:19890388

Ranjan, Amaresh K.; Kumar, Umesh; Hardikar, Ashutosh A.; Poddar, Pankaj; Nair, Prabha D.; Hardikar, Anandwardhan A.

2009-01-01

278

Estimate of the Contribution of Localized Light Absorption by Blood Vessels to the Optical Properties of Biological tissue  

NASA Astrophysics Data System (ADS)

A simple analytical procedure of considering localized light absorption by blood vessels and its effect on the absorption characteristics of multicomponent biological tissue is proposed. The final results are presented in the form of a single integral of elementary functions. A comparison of the estimates obtained with data in the literature shows their good agreement. The limiting cases of random and ordered arrangement of vessels are considered. It was shown that, in the blue spectral range, the absorption coefficient of biological tissues can reach saturation when it ceases to be dependent on the optical characteristics of blood and is determined only by the diameter of vessels and their volume concentration. The depth of light penetration into tissue and the reflection coefficient of tissue are estimated for both a localized and a homogeneously distributed absorber. Possible biomedical applications of the results obtained are illustrated.

Barun, V. V.; Ivanov, A. P.

2004-11-01

279

Relation of pacing-induced coronary resistance vessel dilation to total serum cholesterol and heart rate-blood pressure product  

Microsoft Academic Search

Coronary risk factors adversely affect coronary resistance vessel dilation to acetylcholine, but little is known about the effect of risk factors on coronary blood flow (CBF) responses to physiologic stimuli. CBF was derived from Doppler flow velocity (0.018-inch Doppler wire) and coronary diameter (quantitative angiography) in response to rapid atrial pacing in 50 patients (mean age 52 12 years).

Todd J. Anderson; David M. Goodhart; Mouhiedin Traboulsi; Merril L. Knudtson

1997-01-01

280

In vivo visualization of Bonghan ducts inside blood vessels of mice by using an Alcian blue staining method  

Microsoft Academic Search

An in vivo method using Alcian blue (AB) was developed for visualizing floating threadlike tissues inside blood vessels of mice. These novel structures called intravascular Bonghan ducts (IBHDs) are considered as extension of acupuncture meridians. For in vivo imaging of IBHDs, AB solution (pH 7.4) that stains mucopolysaccharides like hyaluronic acid was used. After injecting AB solution into the femoral

Jung Sun Yoo; Min Su Kim; Vyacheslav Ogay; Kwang-Sup Soh

281

High tissue glucose alters intersomitic blood vessels in zebrafish via methylglyoxal targeting the VEGF receptor signaling cascade.  

PubMed

Hyperglycemia causes micro- and macrovascular complications in diabetic patients. Elevated glucose concentrations lead to increased formation of the highly reactive dicarbonyl methylglyoxal (MG), yet the early consequences of MG for development of vascular complications in vivo are poorly understood. In this study, zebrafish were used as a model organism to analyze early vascular effects and mechanisms of MG in vivo. High tissue glucose increased MG concentrations in tg(fli:EGFP) zebrafish embryos and rapidly induced several additional malformed and uncoordinated blood vessel structures that originated out of existing intersomitic blood vessels (ISVs). However, larger blood vessels, including the dorsal aorta and common cardinal vein, were not affected. Expression silencing of MG-degrading enzyme glyoxalase (glo) 1 elevated MG concentrations and induced a similar vascular hyperbranching phenotype in zebrafish. MG enhanced phosphorylation of vascular endothelial growth factor (VEGF) receptor 2 and its downstream target Akt/protein kinase B (PKB). Pharmacological inhibitors for VEGF receptor 2 and Akt/PKB as well as MG scavenger aminoguanidine and glo1 activation prevented MG-induced hyperbranching of ISVs. Taken together, MG acts on smaller blood vessels in zebrafish via the VEGF receptor signaling cascade, thereby describing a new mechanism that can explain vascular complications under hyperglycemia and elevated MG concentrations. PMID:25092676

Jrgens, Kristina; Stoll, Sandra J; Pohl, Jennifer; Fleming, Thomas H; Sticht, Carsten; Nawroth, Peter P; Hammes, Hans-Peter; Kroll, Jens

2015-01-01

282

Detection of blood vessels in human brain 3D magnetic resonance images with the use of mathematical morphology and region growing algorithms  

NASA Astrophysics Data System (ADS)

Detection and quantitative parameterization of brain blood vessels in magnetic resonance images (MRI) are an important aid to diagnosing neoplasmic diseases, planning surgical operations or detecting the atrophy of blood vessels. Fast and effective computer programs are needed to extract quantitative information from MRI data - to increase objectivity, accuracy and repeatability of the diagnosis. To develop such programs we must use algorithms for 3D images segmentation, necessary to build geometrical models of the blood vessels. These models are then used for vessel tree visualization and quantitative description.

Sankowski, Adam; Materka, Andrzej

2009-06-01

283

Simulations and Experiments about the Influence of HMME Concentration in Blood Vessel during a Short Time on Photodynamic Therapy Microvascular Effect  

Microsoft Academic Search

Objective: Study the influence of Hematoporphyrin Monomethyl Ether (HMME) concentration in blood vessel in a rather short time on photodynamic therapy (PDT) microvascular effect by mathematical modeling and animal experiment. Methods: The yields of singlet oxygen in blood vessel in a short time in different animal were simulated by mathematical model, and the yields of singlet oxygen in Leghorn Cocks

N. Y. Huang; Y. Gu; F. G. Liu; G. Cheng; Q. H. Zhong; Y. Wang; H. X. Qiu; L. H. Liu; J. Zeng

2007-01-01

284

Linear and branched perfluorooctane sulfonate (PFOS) isomer patterns differ among several tissues and blood of polar bears.  

PubMed

Perfluorooctane sulfonate (PFOS) is a globally distributed persistent organic pollutant that has been found to bioaccumulate and biomagnify in aquatic food webs. Although principally in its linear isomeric configuration, 21-35% of the PFOS manufactured via electrochemical fluorination is produced as a branched structural isomer. PFOS isomer patterns were investigated in multiple tissues of polar bears (Ursus maritimus) from East Greenland. The liver (n = 9), blood (n = 19), brain (n = 16), muscle (n = 5), and adipose (n = 5) were analyzed for linear PFOS (n-PFOS), as well as multiple mono- and di-trifluoromethyl-substituted branched isomers. n-PFOS accounted for 93.0 0.5% of ?-PFOS isomer concentrations in the liver, whereas the proportion was significantly lower (p<0.05) in the blood (85.4 0.5%). Branched isomers were quantifiable in the liver and blood, but not in the brain, muscle, or adipose. In both the liver and blood, 6-perfluoromethylheptane sulfonate (P6MHpS) was the dominant branched isomer (2.61 0.10%, and 3.26 0.13% of ?-PFOS concentrations, respectively). No di-trifluoromethyl-substituted isomers were detectable in any of the tissues analyzed. These tissue-specific isomer patterns suggest isomer-specific pharmacokinetics, perhaps due to differences in protein affinities, and thus differences in protein interactions, as well transport, absorption, and/or metabolism in the body. PMID:23920361

Greaves, Alana K; Letcher, Robert J

2013-09-01

285

PEG-albumin supraplasma expansion is due to increased vessel wall shear stress induced by blood viscosity shear thinning  

PubMed Central

We studied the extreme hemodilution to a hematocrit of 11% induced by three plasma expanders: polyethylene glycol (PEG)-conjugated albumin (PEG-Alb), 6% 70-kDa dextran, and 6% 500-kDa dextran. The experimental component of our study relied on microelectrodes and cardiac output to measure both the rheological properties of plasma-expander blood mixtures and nitric oxide (NO) bioavailability in vessel walls. The modeling component consisted of an analysis of the distribution of wall shear stress (WSS) in the microvessels. Our experiments demonstrated that plasma expansion with PEG-Alb caused a state of supraperfusion with cardiac output 40% above baseline, significantly increased NO vessel wall bioavailability, and lowered peripheral vascular resistance. We attributed this behavior to the shear thinning nature of blood and PEG-Alb mixtures. To substantiate this hypothesis, we developed a mathematical model of non-Newtonian blood flow in a vessel. Our model used the Quemada rheological constitutive relationship to express blood viscosity in terms of both hematocrit and shear rate. The model revealed that the net effect of the hemodilution induced by relatively low-viscosity shear thinning PEG-Alb plasma expanders is to reduce overall blood viscosity and to increase the WSS, thus intensifying endothelial NO production. These changes act synergistically, significantly increasing cardiac output and perfusion due to lowered overall peripheral vascular resistance. PMID:22505638

Sriram, Krishna; Tsai, Amy G.; Cabrales, Pedro; Meng, Fantao; Acharya, Seetharama A.; Tartakovsky, Daniel M.

2012-01-01

286

Numerical modeling of the pulse wave propagation in large blood vessels based on liquid and wall interaction  

NASA Astrophysics Data System (ADS)

The purpose of this article is to develop a non-linear, one-dimensional model of pulse wave propagation in the arterial cardiovascular system. The model includes partial differential equations resulting from the balance of mass and momentum for the fluid-filled area and the balance equation for the area of the wall and vessels. The considered mathematical model of pulse wave propagation in the thoracic aorta section takes into account the viscous dissipation of fluid energy, realistic values of parameters describing the physicochemical properties of blood and vessel wall. Boundary and initial conditions contain the appropriate information obtained from in vivo measurements. As a result of the numerical solution of the mass and momentum balance equations for the blood and the equilibrium equation for the arterial wall area, time- dependent deformation, respective velocity profiles and blood pressure were determined.

Rup, K.; Dr?d?, A.

2014-08-01

287

[Histologic study of the teleost liver. II. The blood vessel system].  

PubMed

In the liver of the teleosts investigated in the present study the sinusoidal region shows a space of DISSE, which contains numerous microvilli originating from the hepatocytes. In some species, especially in Tetraodon leiurus, there are also bundles of collagenous fibrils. In the DISSE's space of larger sinusoids (transition sinusoids) sections of filament-rich cells are found. These are sometimes interconnected by desmosomes and can be interpreted as processes of smooth muscle cells from the region of the venae hepaticae. The endothelium of smaller sinusoids is fenestrated and shows micropinocytotic activity. The endothelia of the transition sinusoids and of the venae hepaticae are endowed with structures, which can be interpreted as macrovesicles. In the sinusoidal region true KUPFFER-cells and ITO-cells could not be observed. Nevertheless, the close location of granulocytes to the sinusoidal endothelium suggests that phagocytotic processes cannot be excluded for the sinusoidal region. Exceptionally, in Hemihaplochromis multicolor there were also signs of possible phagocytosis by sinusoidal endothelial cells. The chemomorphology of the sinusoidal region, above all the evidence of alkaline phosphatase, shows great differences between species. The examination of the larger blood-vessels in the liver of Haplochromis burtoni reveals venae portae with very thin walls and venae hepaticae with thick walls, which contain smooth muscle cells. Granulocytes and melanocytes are abundant in the wall of the venae hepaticae. This phenomenon indicates that the defence-functions, which in the liver of higher vertebrates are carried out by the sinusoids (KUPFFER-cells), are undertaken by the region of the venae hepaticae in the liver of Haplochromis burtoni, which is free of KUPFFER-cells. On their extrahepatic course the venae portae are surrounded by a sleeve of exocrine pancreatic tissue, which accompanies the vessels deep into the liver. The pancreatic cells bordering the thin-walled venae portae have sparse microvilli indicating a transfer of substances between venous blood and pancreas similar to the sinusoidal region of the liver. Furthermore, the investigation resulted in a clue to the innervation of the exocrine pancreas. PMID:545930

Langer, M

1979-01-01

288

Rapid sealing and cutting of porcine blood vessels, ex vivo, using a high-power, 1470-nm diode laser.  

PubMed

Suture ligation with subsequent cutting of blood vessels to maintain hemostasis during surgery is time consuming and skill intensive. Energy-based electrosurgical and ultrasonic devices are often used to replace sutures and mechanical clips to provide rapid hemostasis and decrease surgery time. Some of these devices may create undesirably large collateral zones of thermal damage and tissue necrosis, or require separate mechanical blades for cutting. Infrared lasers are currently being explored as alternative energy sources for vessel sealing applications. In a previous study, a 1470-nm laser was used to seal vessels 1 to 6 mm in diameter in 5 s, yielding burst pressures of ?500??mmHg. The purpose of this study was to provide vessel sealing times comparable with current energy-based devices, incorporate transection of sealed vessels, and demonstrate high vessel burst pressures to provide a safety margin for future clinical use. A 110-W, 1470-nm laser beam was transmitted through a fiber and beam shaping optics, producing a 90-W linear beam 3.0 by 9.5 mm for sealing (400??W/cm2), and 1.1 by 9.6 mm for cutting (1080??W/cm2). A two-step process sealed and then transected ex vivo porcine renal vessels (1.5 to 8.5 mm diameter) in a bench top setup. Seal and cut times were 1.0 s each. A burst pressure system measured seal strength, and histologic measurements of lateral thermal spread were also recorded. All blood vessels tested (n=55 seal samples) were sealed and cut, with total irradiation times of 2.0 s and mean burst pressures of 1305783??mmHg. Additional unburst vessels were processed for histological analysis, showing a lateral thermal spread of 0.940.48??mm (n=14 seal samples). This study demonstrated that an optical-based system is capable of precisely sealing and cutting a wide range of porcine renal vessel sizes and, with further development, may provide an alternative to radiofrequency- and ultrasonic-based vessel sealing devices. PMID:24658792

Giglio, Nicholas C; Hutchens, Thomas C; Perkins, William C; Latimer, Cassandra; Ward, Arlen; Nau, William H; Fried, Nathaniel M

2014-03-01

289

Fusing VE-cadherin to ?-catenin impairs fetal liver hematopoiesis and lymph but not blood vessel formation.  

PubMed

We have recently shown that genetic replacement of VE-cadherin by a VE-cadherin-?-catenin fusion construct strongly impairs opening of endothelial cell contacts during leukocyte extravasation and induction of vascular permeability in adult mice. Here we show that this mutation leads to lethality at midgestation on a clean C57BL/6 background. Investigating the reasons for embryonic lethality, we observed a lack of fetal liver hematopoiesis and severe lymphedema but no detectable defects in blood vessel formation and remodeling. As for the hematopoiesis defect, VE-cadherin-?-catenin affected neither the generation of hematopoietic stem and progenitor cells (HSPCs) from hemogenic endothelium nor their differentiation into multiple hematopoietic lineages. Instead, HSPCs accumulated in the fetal circulation, suggesting that their entry into the fetal liver was blocked. Edema formation was caused by disturbed lymphatic vessel development. Lymphatic progenitor cells of VE-cadherin-?-catenin-expressing embryos were able to leave the cardinal vein and migrate to the site of the first lymphatic vessel formation, yet subsequently, these cells failed to form large lumenized lymphatic vessels. Thus, stabilizing endothelial cell contacts by a covalent link between VE-cadherin and ?-catenin affects recruitment of hematopoietic progenitors into the fetal liver and the development of lymph but not blood vessels. PMID:24567373

Dartsch, Nina; Schulte, Drte; Hgerling, Ren; Kiefer, Friedemann; Vestweber, Dietmar

2014-05-01

290

Effects of ovariectomy and hormone replacement on collagen and blood vessels of the urethral submucosa of rats.  

PubMed

Collagen and blood vessels of the urethral submucosa of ovariectomized rats were studied following 28 daily subcutaneous injections of 17-beta estradiol (n=6, group 1), medroxy-progesterone acetate (n=6, group 2), both drugs (n=6, group 3) or vehicle (n= 6, control) and after sham surgery without castration or injection (n=6). Investigations included the immunohistochemistry of estrogen and progesterone receptors and collagen fibres, Western blot analysis of collagen types I and III and counting periurethral vessels by light microscopy. Our results showed positive immunostaining with estrogen, progesterone and collagen types I and III in all samples. Collagen type I and III levels were lower in the controls than in the sham group. The other groups showed increases (2>3>1) over the controls with a relatively higher increase in type III. The type I/III collagen ratio progressively decreased (control>1>2>3) below sham levels. The mean vessel count was significantly lower in control than in sham animals (P<0.00001). However, only estrogen treatment significantly increased the vessel number compared to controls (P=0.04). Our results indicate that estrogen and progesterone, alone or in combination, have an effect on collagen types I and III, and that estrogen has an effect on blood vessels of the urethral submucosa in female rats. PMID:12669156

Rizk, Diaa E E; Mensah-Brown, Eric P; Chandranath, Swaminathan I; Ahmed, Ijaz; Shafiullah, Mohamed; Patel, Mahendra; Al-Haj, Mahmoud; Adem, Abdu

2003-07-01

291

Blood flow reduction of covered small side branches after flow diverter treatment: A computational fluid hemodynamic quantitative analysis.  

PubMed

Small side branches related brain infarction remains one of the major concerns for flow-diverter devices. However, among several factors, whether this high-profile stent would significantly block blood flow into small side branches remains unclear. The authors quantitatively evaluate blood flow reduction due to the deployment of flow-diverter devices using computational fluid dynamics approach. Thirty one patient-specific anterior inferior cerebellar artery geometries were employed. The flow-diverter device was hypothetically embedded into the basilar trunk, and to cover the anterior inferior cerebellar arteries. The blood flow reduction of each anterior inferior cerebellar artery following flow-diverter device deployment was calculated, with independent validations for both inflow and outflow conditions. Efficient diameters of the anterior inferior cerebellar arteries were calculated to evaluate any correlation with blood flow reduction after flow-diverter devices. The blood flow reduction ratio was shown to be 3.611.94%. There was moreover no significant difference of either inflow or outflow boundary conditions during the simulation. The results were calculated approximately as a modest linear correlation between the blood flow reduction ratio and the size of anterior anterior inferior cerebellar arteries which had a mean efficient diameter of 1.120.36mm (range from 0.31mm to 1.91mm), and the R(2) was 0.361. When covered by flow-diverter devices, the mechanical blood flow reduction in anterior inferior cerebellar arteries was found to be low with a maximum value estimated to be less than 8%. Therefore, mechanical blood flow reduction is probably not the leading factor contributing to small side branches related brain infarction. PMID:25748223

Hu, Peng; Qian, Yi; Zhang, Yu; Zhang, Hong-Qi; Li, Yang; Chong, Winston; Ling, Feng

2015-04-13

292

Due to intravascular multiple sequential scattering, Diffuse Correlation Spectroscopy of tissue primarily measures relative red blood cell motion within vessels  

PubMed Central

We suggest that Diffuse Correlation Spectroscopy (DCS) measurements of tissue blood flow primarily probe relative red blood cell (RBC) motion, due to the occurrence of multiple sequential scattering events within blood vessels. The magnitude of RBC shear-induced diffusion is known to correlate with flow velocity, explaining previous reports of linear scaling of the DCS blood flow index with tissue perfusion despite the observed diffusion-like auto-correlation decay. Further, by modeling RBC mean square displacement using a formulation that captures the transition from ballistic to diffusive motion, we improve the fit to experimental data and recover effective diffusion coefficients and velocity de-correlation time scales in the range expected from previous blood rheology studies. PMID:21750779

Carp, Stefan A.; Roche-Labarbe, Nadege; Franceschini, Maria-Angela; Srinivasan, Vivek J.; Sakadi?, Sava; Boas, David A.

2011-01-01

293

Astrocytes and Blood Vessels Define the Foveal Rim during Primate Retinal Development  

Microsoft Academic Search

RESULTS. From Fd88 to 115, vessels on the horizontal meridian were found only at the level of the ganglion cell layer (GCL)-inner plexiform layer (IPL) border where they form the ganglion cell layer plexus (GCP). Stellate astrocytes accompany GCP vessels and extend closer to the fovea than vessels. The foveal avascular zone was present within the GCP at Fd101, and

Jan M. Provis; Trent Sandercoe; Anita E. Hendrickson

2000-01-01

294

Noncoding RNAs regulate NF-?B signaling to modulate blood vessel inflammation  

PubMed Central

Cardiovascular diseases such as atherosclerosis are one of the leading causes of morbidity and mortality worldwide. The clinical manifestations of atherosclerosis, which include heart attack and stroke, occur several decades after initiation of the disease and become more severe with age. Inflammation of blood vessels plays a prominent role in atherogenesis. Activation of the endothelium by inflammatory mediators leads to the recruitment of circulating inflammatory cells, which drives atherosclerotic plaque formation and progression. Inflammatory signaling within the endothelium is driven predominantly by the pro-inflammatory transcription factor, NF-?B. Interestingly, activation of NF-?B is enhanced during the normal aging process and this may contribute to the development of cardiovascular disease. Importantly, studies utilizing mouse models of vascular inflammation and atherosclerosis are uncovering a network of noncoding RNAs, particularly microRNAs, which impinge on the NF-?B signaling pathway. Here we summarize the literature regarding the control of vascular inflammation by microRNAs, and provide insight into how these microRNA-based pathways might be harnessed for therapeutic treatment of disease. We also discuss emerging areas of endothelial cell biology, including the involvement of long noncoding RNAs and circulating microRNAs in the control of vascular inflammation. PMID:25540650

Cheng, Henry S.; Njock, Makon-Sbastien; Khyzha, Nadiya; Dang, Lan T.; Fish, Jason E.

2014-01-01

295

Potential Approaches to Enhance the Effects of Estrogen on Senescent Blood Vessels and Postmenopausal Cardiovascular Disease  

PubMed Central

Cardiovascular disease (CVD) is more common in postmenopausal than premenopausal women, suggesting vascular protective effects of estrogen. Vascular estrogen receptors ER?, ER? and a transmembrane estrogen-binding protein GPR30 have been described. Also, experimental studies have demonstrated vasodilator effects of estrogen on the endothelium, vascular smooth muscle and extracellular matrix. However, randomized clinical trials have not supported vascular benefits of menopausal hormone therapy (MHT), possibly due to the subjects' advanced age and age-related changes in estrogen synthesis and metabolic pathways, the vascular ERs number, distribution and integrity, and the post-ER vascular signaling pathways. Current MHT includes natural estrogens such as conjugated equine estrogen, as well as synthetic and semi-synthetic estrogens. New estrogenic formulations and hormone combinations have been developed. Phytoestrogens is being promoted as an alternative MHT. Specific ER modulators (SERMs), and selective agonists for ER? such as PPT, ER? such as DPN, and GPR30 such as G1 are being evaluated. In order to enhance the vascular effectiveness of MHT, its type, dose, route of administration and timing may need to be customized depending on the subject's age and pre-existing CVD. Also, the potential interaction of estrogen with progesterone and testosterone on vascular function may need to be considered in order to maximize the vascular benefits of MHT on senescent blood vessels and postmenopausal CVD. PMID:20210774

Khalil, Raouf A.

2010-01-01

296

Mast Cells Present Protrusions into Blood Vessels upon Tracheal Allergen Challenge in Mice  

PubMed Central

Mast cells (MC) and myeloid dendritic cells (DC) act proximally in detecting and processing antigens and immune insults. We sought to understand their comparative dynamic behavior with respect to the airway epithelium in the steady state and in response to an allergic stimulus in mouse trachea. We devised methods to label MC in living trachea and to demonstrate that MC and DC occupy distinct layers of the tracheal mucosa, with DC being closer to the lumen. DC numbers doubled after allergen challenge, but MC numbers remained stable. MC and DC migrated minimally in either steady state or allergen-challenge conditions, and their interactions with one another appeared to be stochastic and relatively infrequent. While DC, unlike MC, exhibited probing behaviors involving dendrites, these projections did not cross the epithelium into the airway lumen. MC typically were located too far from the epithelial surface to contact the tracheal lumen. However, MC had protrusions toward and into blood vessels, likely to load with IgE. Thus, DC and MC occupy distinct niches and engage in sessile surveillance in the mouse trachea. Little or no access of these cell types to the airway lumen suggests that trans-epithelial transport of proteins in the steady state would be required for them to access luminal antigens. PMID:25789765

Looney, Mark R.; Cheng, Laurence E.; McDonald, Donald M.; Caughey, George H.; Krummel, Matthew F.

2015-01-01

297

Regulation of signaling interactions and receptor endocytosis in growing blood vessels.  

PubMed

Blood vessels and the lymphatic vasculature are extensive tubular networks formed by endothelial cells that have several indispensable functions in the developing and adult organism. During growth and tissue regeneration but also in many pathological settings, these vascular networks expand, which is critically controlled by the receptor EphB4 and the ligand ephrin-B2. An increasing body of evidence links Eph/ephrin molecules to the function of other receptor tyrosine kinases and cell surface receptors. In the endothelium, ephrin-B2 is required for clathrin-dependent internalization and full signaling activity of VEGFR2, the main receptor for vascular endothelial growth factor. In vascular smooth muscle cells, ephrin-B2 antagonizes clathrin-dependent endocytosis of PDGFR? and controls the balanced activation of different signal transduction processes after stimulation with platelet-derived growth factor. This review summarizes the important roles of Eph/ephrin molecules in vascular morphogenesis and explains the function of ephrin-B2 as a molecular hub for receptor endocytosis in the vasculature. PMID:25482636

Pitulescu, Mara E; Adams, Ralf H

2014-01-01

298

Immune Reactivity in Psoriatic Munro-Saboureau Microabscesses, Stratum Corneum and Blood Vessels  

PubMed Central

Background: A characteristic feature of early active psoriatic lesions is the intraepidermal penetration of neutrophils, with attendant formation of Munro-Saboureau microabscesses. Previous immunofluorescence studies have shown reactivity of in vivo binding of stratum corneum antibodies (SCAs) within the Munro-Saboreau microabscesses in cases of psoriasis. Aims: In our study, we aimed to investigate any correlation between the SCAs and the Munro-Saboureau microabscesses. Materials and Methods: We investigated 50 archival biopsies of psoriasis with Munro-Saboureau microabscesses, and attempted to confirm antibody colocalization within these microabcesses via immunohistochemistry staining. As controls, we utilized 50 skin biopsies from healthy patients undergoing esthetic plastic surgery procedures. Results: Within the Munro-Saboureau microabscesses, the following markers were statistically significantly positive relative to controls: CD1a, CD8, CD23, cyclooxygenase-2, myeloid histoid antigen, albumin, fibrinogen, kappa, lambda, von Willebrand factor, IgG, IgM, IgD, complement/C3c, C3d, myeloperoxidase, and carcinoembryonic antigen (P < 0.05). Autoreactivity to blood vessels was also detected, with multiple immunoglobulins and complement factors. Conclusions: We document important correlations between the Munro-Saboureau microabscesses, SCAs, and other immunoreactants. PMID:22754876

Abreu-Velez, Ana Maria; Googe, Paul B; Howard, Michael S

2012-01-01

299

Investigation of source-detector separation optimization for an implantable perfusion and oxygenation sensor for liver blood vessels  

SciTech Connect

An implanted system is being developed to monitor transplanted liver health during the critical 7-10 day period posttransplantation. The unit will monitor organ perfusion and oxygen consumption using optically-based probes placed on both the inflow and outflow blood vessels, and on the liver parenchymal surface. Sensing probes are based on a 3- wavelength LED source and a photodiode detector. Sample diffuse reflectance is measured at 735, 805, and 940 nm. To ascertain optimal source-to-photodetector spacing for perfusion measurement in blood vessels, an ex vivo study was conducted. In this work, a dye mixture simulating 80% blood oxygen saturation was developed and perfused through excised porcine arteries while collecting data for various preset probe source-to-photodetector spacings. The results from this study demonstrate a decrease in the optical signal with decreasing LED drive current and a reduction in perfusion index signal with increasing probe spacing. They also reveal a 2- to 4-mm optimal range for blood vessel perfusion probe source-to-photodetector spacing that allows for sufficient perfusion signal modulation depth with maximized signal to noise ratio (SNR). These findings are currently being applied to guide electronic configuration and probe placement for in vivo liver perfusion porcine model studies.

Baba, Justin S [ORNL; Akl, Tony [Texas A& M University; Cote, Gerard L. [Texas A& M University; Wilson, Mark A. [University of Pittsburgh School of Medicine, Pittsburgh PA; Ericson, Milton Nance [ORNL

2011-01-01

300

Investigation of source-detector separation optimization for an implantable perfusion and oxygenation sensor for liver blood vessels  

NASA Astrophysics Data System (ADS)

An implanted system is being developed to monitor transplanted liver health during the critical 7-10 day period posttransplantation. The unit will monitor organ perfusion and oxygen consumption using optically-based probes placed on both the inflow and outflow blood vessels, and on the liver parenchymal surface. Sensing probes are based on a 3- wavelength LED source and a photodiode detector. Sample diffuse reflectance is measured at 735, 805, and 940 nm. To ascertain optimal source-to-photodetector spacing for perfusion measurement in blood vessels, an ex vivo study was conducted. In this work, a dye mixture simulating 80% blood oxygen saturation was developed and perfused through excised porcine arteries while collecting data for various preset probe source-to-photodetector spacings. The results from this study demonstrate a decrease in the optical signal with decreasing LED drive current and a reduction in perfusion index signal with increasing probe spacing. They also reveal a 2- to 4-mm optimal range for blood vessel perfusion probe source-to-photodetector spacing that allows for sufficient perfusion signal modulation depth with maximized signal to noise ratio (SNR). These findings are currently being applied to guide electronic configuration and probe placement for in vivo liver perfusion porcine model studies.

Baba, J. S.; Akl, T. J.; Cot, G. L.; Wilson, M. A.; Ericson, M. N.

2011-03-01

301

Dual beam Doppler FD-OCT system with integrated Dynamic Vessel Analyzer and rotatable beams to measure total retinal blood flow  

NASA Astrophysics Data System (ADS)

We present a method capable of measuring the total retinal blood flow in arteries and veins based on dual beam Fourierdomain Doppler optical coherence tomography (OCT) in combination with a fundus camera based Dynamic Vessel Analyzer. Incorporating a Dynamic vessel analyzer into the system not only gives a live image of the fundus - it also allows determining the vessels' diameter precisely during the OCT measurement, which is necessary for the determination of the blood flow. While dual beam systems with fixed detection plane allow only vessels with certain orientations to be measured, the detection plane of our system can be rotated by 90. This ensures that the blood's velocity can be measured in all vessels around the optic nerve head. The results of the total blood flow measurements are in the same range as previously published data. Additionally, the high degree of conformity between the measured venous and arterial flow corroborated the system's validity. For larger vessels, the logarithmic values of vessel diameter and blood flow were found to be related linearly with a regression coefficient of around 3, which is in accordance with Murray's law. For smaller vessels (diameter below 60 ?m), the values diverge from the linear dependence. The high sensitivity and the good agreement with published data suggest a high potential for examining the retinal blood flow in patients with ocular diseases.

Doblhoff-Dier, Veronika; Werkmeister, Ren M.; Grschl, Martin; Schmetterer, Leopold

2014-03-01

302

Molecular dynamics simulation of soft grains: Malaria-infected red blood cells motion within obstructed 2-D capillary vessel  

NASA Astrophysics Data System (ADS)

Molecular dynamics has been widely used to numerically solve equation of motion of classical many-particle system. It can be used to simulate many systems including biophysics, whose complexity level is determined by the involved elements. Based on this method, a numerical model had been constructed to mimic the behaviour of malaria-infected red blood cells within capillary vessel. The model was governed by three forces namely Coulomb force, normal force, and Stokes force. By utilizing two dimensional four-cells scheme, theoretical observation was carried out to test its capability. Although the parameters were chosen deliberately, all of the quantities were given arbitrary value. Despite this fact, the results were quite satisfactory. Combined with the previous results, it can be said that the proposed model were sufficient enough to mimic the malaria-infected red blood cells motion within obstructed capillary vessel.

Haris, L.; Khotimah, S. N.; Haryanto, F.; Viridi, S.

2014-02-01

303

Ex vivo bubble production from ovine large blood vessels: size on detachment and evidence of "active spots".  

PubMed

Nanobubbles formed on the hydrophobic silicon wafer were shown to be the source of gas micronuclei from which bubbles evolved during decompression. Bubbles were also formed after decompression on the luminal surface of ovine blood vessels. Four ovine blood vessels: aorta, pulmonary vein, pulmonary artery, and superior vena cava, were compressed to 1013 kPa for 21 h. They were then decompressed, photographed at 1-s intervals, and bubble size was measured on detachment. There were certain spots at which bubbles appeared, either singly or in a cluster. Mean detachment diameter was between 0.7 and 1.0 mm. The finding of active spots at which bubbles nucleate is a new, hitherto unreported observation. It is possible that these are the hydrophobic spots at which bubbles nucleate, stabilise, and later transform into the gas micronuclei that grow into bubbles. The possible neurological effects of these large arterial bubbles should be further explored. PMID:24933644

Arieli, R; Marmur, A

2014-08-15

304

Two-layered model of Casson fluid flow through stenotic blood vessels: applications to the cardiovascular system.  

PubMed

The effects of peripheral layer viscosity on physiological characteristics of blood flow through the artery with mild stenosis have been investigated. Blood has been represented by a two-fluid model, consisting of a core region of suspension of all the erythrocytes assumed to be a Casson fluid and a peripheral layer of plasma as a Newtonian fluid. The study is based on theoretical considerations and numerical evaluations and is restricted to the flow of blood through small arteries (130-1000 microns in diameter). It has been found that the resistance to flow and the wall shear stress decrease as the peripheral layer viscosity decreases. These characteristics are found to be decreasing as peripheral layer thickness increases. The numerical results show that the existence of the peripheral layer is helpful in functioning of the diseased arterial system. The analysis has been applied to calculate the resistance to flow and wall shear stress in different blood vessels. PMID:8063842

Srivastava, V P; Saxena, M

1994-07-01

305

Interleukin-10 induces E-selectin on small and large blood vessel endothelial cells  

PubMed Central

In vitro, expression of E-selectin is largely restricted to endothelial cells activated by inflammatory cytokines. Under activated conditions, cytokines such as interleukin (IL) 10, released by keratinocytes in large quantities, may also increase the expression of E-selectin on the dermal microvasculature. The aim of the present study was to investigate the expression of E-selectin on cultured human dermal microvascular endothelial cells (HDMEC) isolated from neonatal foreskins when exposed to IL-10. Expression of E-selectin was determined by immunofluorescence microscopy, FACS analysis, an HL-60 cell-binding assay, and quantitative polymerase chain reaction (PCR) analysis. For comparison with large blood vessel cells, the expression of E-selectin on human umbilical vein endothelial cells (HUVEC) was also determined in parallel by FACS and reverse transcriptase-PCR analysis under identical conditions. These studies demonstrate that IL- 10 induces the expression of E-selectin on both HDMEC and HUVEC and that the level of expression of HDMEC is comparable with that induced by IL-1 beta and tumor necrosis factor-alpha. When HL-60 cells are incubated with HDMEC pretreated with IL-10, a consistent increase in adherence of HL-60 to endothelial cells is observed. This adherence was found to be mediated by L-selectin. PCR analysis and the quantification of E-selectin cDNA by a novel, highly sensitive and specific PCR- immunoassay demonstrate the induction of E-selectin mRNA at the transcriptional level. The induction of the expression of E-selectin by IL-10 on HDMEC may provide additional insights into the pathogenic mechanism of neutrophil accumulation at the site of inflammation in inflammatory skin diseases. PMID:9064342

1996-01-01

306

Estrogenic Compounds, Estrogen Receptors and Vascular Cell Signaling in the Aging Blood Vessels  

PubMed Central

The cardiovascular benefits of menopausal hormone therapy (MHT) remain controversial. The earlier clinical observations that cardiovascular disease (CVD) was less common in MHT users compared to non-users suggested cardiovascular benefits of MHT. Also, experimental studies have identified estrogen receptors ER?, ER? and GPR30, which mediate genomic or non-genomic effects in vascular endothelium, smooth muscle, and extracellular matrix (ECM). However, data from randomized clinical trials (RCTs), most notably the Women's Health Initiative (WHI) study, have challenged the cardiovascular benefits and highlighted adverse cardiovascular events with MHT. The discrepancies have been attributed to the design of RCTs, the subjects' advanced age and preexisting CVD, and the form of estrogen used. The discrepancies may also stem from age-related changes in vascular ER amount, distribution, integrity, and post-receptor signaling pathways as well as structural changes in the vasculature. Age-related changes in other sex hormones such as testosterone may also alter the hormonal environment and influence the cardiovascular effects of estrogen. Investigating the chemical properties, structure-activity relationship and pharmacology of natural and synthetic estrogens should improve the effectiveness of conventional MHT. Further characterization of phytoestrogens, selective estrogen-receptor modulators (SERMs), and specific ER agonists may provide substitutes to conventional MHT. Conditions with excess or low estrogen levels such as polycystic ovary syndrome (PCOS) and Turner syndrome may provide insight into the development and regulation of ER and the mechanisms of aberrant estrogen-ER interactions. The lessons learned from previous RCTs have led to more directed studies such as the Kronos Early Estrogen Prevention Study (KEEPS). Careful design of experimental models and RCTs, coupled with the development of specific ER modulators, hold the promise of improving the actions of estrogen in the aging blood vessels and thereby enhancing the efficacy and safety of MHT in postmenopausal CVD. PMID:19442151

Smiley, Dia A.; Khalil, Raouf A.

2010-01-01

307

Ex vivo expansion of hematopoietic stem cells derived from umbilical cord blood in rotating wall vessel.  

PubMed

Expansion of umbilical cord blood mononuclear cells (UCB MNCs) was carried out in a rotating wall vessel (RWV) bioreactor and tissue culture flasks (T-flasks) in serum-containing medium supplemented with relatively low doses of purified recombinant human cytokines (5.33 ng/ml IL-3, 16 ng/ml SCF, 3.33 ng/ml G-CSF, 2.13 ng/ml GM-CSF, 7.47 ng/ml FL and 7.47 ng/ml TPO) for 8 days. The cell density, pH and osmolality of the culture medium in the two culture systems were measured every 24h. Flow cytometric assay for CD34+ cells was carried out at 0, 144 and 197 h and methylcellulose colony assays were performed at 0, 72, 144 and 197 h. The pH and osmolality of the medium in the two culture systems were maintained in the proper ranges for hematopoietic stem cells (HSCs) and progenitors culture. The RWV bioreactor, combined with a cell-dilution feeding protocol, was efficient to expand UCB MNCs. At the end of 200 h culture, the total cell number was multiplied by 435.5+/-87.6 times, and CD34+ cells 32.7+/-15.6 times, and colony-forming units of granulocyte-macrophage (CFU-GM) 21.7+/-4.9 times. While in T-flasks, however, total cells density changed mildly, CD34+ cells and CFU-GM decreased in number. It is demonstrated that the RWV bioreactor can provide a better environment for UCB MNCs expansion, enhance the contact between HSCs and accessory cells and make the utilization of cytokines more effective than T-flask. PMID:16513201

Liu, Yang; Liu, Tianqing; Fan, Xiubo; Ma, Xuehu; Cui, Zhanfeng

2006-07-25

308

Prominent expression of sialyl Lewis X-capped core 2-branched O-glycans on high endothelial venule-like vessels in gastric MALT lymphoma.  

PubMed

High endothelial venule (HEV)-like vessels have been observed in gastric B cell lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma), as well as in its preceding lesion, chronic Helicobacter pylori gastritis. Previously we reported that glycans on HEV-like vessels in the latter lesion served as L-selectin ligands, although their function is unclear. We have investigated sialyl Lewis X (sLeX)-related glycoepitopes and found that MECA-79(-) /HECA-452(+) /NCC-ST-439(+) HEV-like vessels preferentially mark gastric MALT lymphoma compared to chronic H. pylori gastritis. We then constructed CHO cell lines expressing potential MECA-79(-) /HECA-452(+) /NCC-ST-439(+) glycans, as well as other sLeX-type glycans, on CD34 and evaluated L-selectin binding to those cells, using L-selectin-IgM chimera binding and lymphocyte adhesion assays. L-selectin-IgM chimeras bound to CHO cells expressing 6-sulpho-sLeX attached to core 2-branched O-glycans with or without 6-sulpho-sLeX attached to extended core 1 O-glycans, but only marginally to other CHO cell lines. By contrast, CHO cells expressing 6-sulpho-sLeX attached to extended core 1 and/or core 2-branched O-glycans, as well as non-sulphated sLeX attached to core 2-branched O-glycans, showed substantial lymphocyte binding, while binding was negligible on lines expressing 6-sulpho- and non-sulphated sLeX attached to N-glycans and non-sulphated sLeX attached to extended core 1 O-glycans. These results indicate that MECA-79(-) /HECA-452(+) /NCC-ST-439(+) glycans, specifically, 6-sulpho- and non-sulphated sLeXs attached to core 2-branched O-glycans, expressed on HEV-like vessels in gastric MALT lymphoma function as L-selectin ligands and likely contribute to H. pylori-specific T cell recruitment in the progression of gastric MALT lymphoma. PMID:21432854

Kobayashi, Motohiro; Mitoma, Junya; Hoshino, Hitomi; Yu, Shin-Yi; Shimojo, Yasuyo; Suzawa, Kenichi; Khoo, Kay-Hooi; Fukuda, Minoru; Nakayama, Jun

2011-05-01

309

Effects of Bufo marinus skin toxins on human fetal extracorporeal blood vesseLS  

Microsoft Academic Search

The effects of extracts of Bufo marinus toad skin toxin on human isolated umbilical arterial rings and the fetal vessels of perfused placentae were examined and compared with those of ouabain, an inhibitor of Na+K+-ATPase. Umbilical artery rings and fetal vessels of the perfused placenta responded to extracts, or ouabain, with constriction which persisted after the removal of each agent.

Thiam H Lim; Ian M Leitch; Alan L. A Boura; Mark A Read; William A. W Walters

1997-01-01

310

Characterization, Localization and Patterning of Lymphatics and Blood Vessels in Oral Squamous Cell Carcinoma: A Comparative Study Using D2-40 and CD-34 IHC Marker  

PubMed Central

Objectives: Lymphatic metastasis has always been regarded as a major prognostic indicator for disease progression and as a guide for therapeutic strategies to oral squamous cell carcinoma (OSCC). Differentiating lymphatic vessels from blood vessels is difficult, partly due to lack of specific method for identifying lymphatics. A new lymphatic vessel reactive antibody D2-40 has been introduced recently. Here we examined immunohistochemical localization of lymphatic vessels and blood vessels using D2-40 and CD-34 respectively in different histological grades of OSCC. Their expression in intra-tumoural and peri-tumoural region was also compared. Materials and Methods: Forty two formalin-fixed paraffin-embedded tissue blocks of excised specimens of OSCC were immunohistochemically evaluated using D2-40 and CD-34 antibodies. Lymphatic vessel density (LVD) (D2-40 positivity) and micro vessel density (MVD) (CD34 positivity) in both intratumoural and peritumoural areas were assessed by hot spot method. Results: Regardless of histopathological differentiation, LVD and MVD in peritumoural areas were found greater than intratumoural areas (p>0.05). Interestingly, other than lymphatic vessels, D2-40 positivity was also detected in tumour cells as well as in basal layer of epithelium adjacent to OSCC. Two patterns of distribution of CD34 positive vessel - circumscribing type and penetrating type were also observed in the cancer nest area. Conclusion: D2-40 can be used as a marker to differentiate lymphatic vessels from blood vessels. Lymphatic and blood vessel proliferation might be much more extensive in the peritumoural area. D2-40 expression in epithelium adjacent to tumour indicates its role in the process of differentiation. Further, its expression in potential malignant disorder may provide better insight in predicting prognosis and pathogenesis of these lesions. PMID:25478456

Agarwal, Deshant; Bajpai, Manas; Gupta, Shailendra; Mathur, Nikunj; Vanaki, S S; Puranik, R S; Mittal, Manoj

2014-01-01

311

Detectability of Small Blood Vessels with High-Frequency Power Doppler and Selection of Wall Filter Cut-Off Velocity for Microvascular Imaging  

Microsoft Academic Search

Power Doppler imaging of physiologic and pathologic angiogenesis is widely used in preclinical studies to track normal development, disease progression and treatment efficacy but can be challenging given the presence of small blood vessels and slow flow velocities. Power Doppler images can be plagued with false-positive color pixels or undetected vessels, thereby complicating the interpretation of vascularity metrics such as

Stephen Z. Pinter; James C. Lacefield

2009-01-01

312

Nestin(+) Tissue-Resident Multipotent Stem Cells Contribute to Tumor Progression by Differentiating into Pericytes and Smooth Muscle Cells Resulting in Blood Vessel Remodeling  

PubMed Central

Tumor vessels with resistance to anti-angiogenic therapy are characterized by the normalization of the vascular structures through integration of mature pericytes and smooth muscle cells (SMC) into the vessel wall, a process termed vessel stabilization. Unfortunately, stabilization-associated vascular remodeling can result in reduced sensitivity to subsequent anti-angiogenic therapy. We show here that blockade of VEGF by bevacizumab induces stabilization of angiogenic tumor blood vessels in human tumor specimen by recruiting Nestin-positive cells, whereas mature vessels down-regulated Nestin-expression. Using xenograft tumors growing on bone-marrow (BM) chimera of C57Bl/6 wildtype and Nestin-GFP transgenic mice, we show for first time that Nestin(+) cells inducing the maturation of tumor vessels do not originate from the BM but presumably reside within the adventitia of adult blood vessels. Complementary ex vivo experiments using explants of murine aortas revealed that Nestin(+) multipotent stem cells (MPSCs) are mobilized from their niche and differentiated into pericytes and SMC through the influence of tumor-cell-secreted factors. We conclude that tissue-resident Nestin(+) cells are more relevant than BM-derived cells for vessel stabilization and therefore have to be considered in future strategies for anti-angiogenic therapy. The identification of proteins mediating recruitment or differentiation of local Nestin(+) cells with potential stem cell character to angiogenic blood vessels may allow the definition of new therapeutic targets to reduce tumor resistance against anti-angiogenic drugs. PMID:25019063

Klein, Diana; Meissner, Nicole; Kleff, Veronika; Jastrow, Holger; Yamaguchi, Masahiro; Ergn, Sleyman; Jendrossek, Verena

2014-01-01

313

Thermal damage of blood vessels in a rat skin-flap window chamber using indocyanine green and a pulsed alexandrite laser: A feasibility study  

Microsoft Academic Search

The design criteria and feasibility of specifically targeting blood vessels for thermal damage by using a pulsed alexandrite\\u000a infra-red laser to heat an intravascularly injected infra-redabsorbing dye, namely indocyanine green (ICG), is demonstrated.\\u000a Theoretical calculations map the distribution of light and heat in and around the subcutaneous blood vessels in a rat skin-flap\\u000a window chamber as functions of dye concentration,

Stephen T. Flock; Steven L. Jacques

1993-01-01

314

619. CoExpression of AAV Mediated Angiopoietin-1 and VEGF in Ischemic Hearts Yield Leakage-Resistant Blood Vessels and Better Therapeutic Effect Than VEGF Alone  

Microsoft Academic Search

Previously, we have shown that vascular endothelial growth factor (VEGF) gene delivered by adeno-associated viral vector (AAV) into ischemic myocardium could induce neoangiogenesis and improve cardiac function. It has been reported that in the skin of transgenic mice, blood vessels induced by over-expressing VEGF were leaky, whereas blood vessels induced by over-expression of angiopoietin-1 were not. Co-expression of angiopoietin-1 and

Hua Su; Shuji Joho; Yu Huang; Alicia Barcena; Janice Arakawa-Hoyt; William Grossman; Yuet W. Kan

2005-01-01

315

In-vivo imaging of blood flow in human retinal vessels using color Doppler optical coherence tomography  

NASA Astrophysics Data System (ADS)

Quantification of retinal blood flow may lead to a better understanding of the progression and treatment of several ocular disorders, including diabetic retinopathy, age- related macular degeneration, and glaucoma. Current techniques, such as fluorescein angiography and laser Doppler velocimetry are limited, failing to provide sufficient information to the clinician. Color Doppler optical coherence tomography (CDOCT) is a novel technique using coherent heterodyne detection for simultaneous cross- sectional imaging of tissue microstructure and blood flow. This technique is capable of high spatial and velocity resolution imaging in highly scattering media. We implemented CDOCT for retinal blood flow mapping in human subjects. No dilation of the pupil was necessary. CDOCT is demonstrated for determining bidirectional flow in sub- 100micrometers diameter vessels in the retina. Additionally, we calculated Doppler broadening using the variance of depth- resolved spectra to identify regions with large velocity gradients within the Xenopus heart. This technique may be useful in quantifying local tissue perfusion in highly vascular retinal tissue.

Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

1999-04-01

316

Analysis of lymphatic and blood vessel invasion biomarkers in T1 esophagogastric adenocarcinomas for improved patient prognostication.  

PubMed

Lymphovascular invasion (LVI) in T1 esophagogastric adenocarcinoma may predict risk of recurrence despite definitive treatment with surgery or endoscopic resection. Podoplanin and CD34 are emerging biomarkers of lymphatic and blood vessel invasion, respectively, and could be adopted to refine LVI assessment. A consecutive series of 65 patients with T1 adenocarcinomas diagnosed at Nottingham University Hospitals were investigated. T1 tumors from 43/65 patients who received primary surgery only were suitable for LVI evaluation by hematoxylin and eosin (H&E) staining as well as by CD34 and Podoplanin immunohistochemistry. LVI was correlated to clinicopathological features and recurrence free survival. H&E staining detected LVI in 11.6% (5/43) of T1 tumors. CD34 and Podoplanin immunohistochemistry significantly improved LVI detection to 25.6% (11/43). Compared with LVI by H&E, immunohistochemical evaluation of blood vessel invasion (CD34) or lymphatic vessel invasion (Podoplanin) was significantly associated with higher grade (P?=?0.005), submucosal invasion (T1b) (P?=?0.018), lymph node positivity (N1) (P?=?0.029) and poor recurrence free survival (P?=?0.0003). Our study provides evidence that CD34 and Podoplanin immunohistochemistry could improve LVI detection and allow better prognostication of patients and optimum selection of definitive treatment. Larger multicenter studies are required for further validation that could have significant clinical implications. PMID:24612464

Perry, C; Soomro, I; Kaye, P; Hardy, E; Parsons, S L; Ragunath, K; Lobo, D N; Martin, S G; Madhusudan, S

2015-04-01

317

Scanning electron microscopic study on the development of primitive blood vessels in chick embryos at the early somite-stage.  

PubMed

Primary vasculogenesis in chick embryos at the early somite stage (1-14 somites) was investigated mainly by scanning electron microscopy (SEM), with special reference to the development of primitive blood vessels such as the arteria et vena vitellina (AV, VV), aorta dorsalis (AD) and vena cardinalis (VC). After glutaraldehyde fixation, the endoderm or ectoderm was removed from the embryos to expose either the ventral (AV, VV, AD) or the dorsal (VC), vascular system. The mode of vascular formation was found to be identical in all these blood vessels, arising first in loco as isolated solid masses or cords composed of so-called angioblasts. The angioblasts at this developmental phase could be distinguished from underlying mesenchymal cells, exhibiting a relatively flat surface. The VV was recognized first on both sides of the anterior intestinal portal at the 4-somite stage, whereas the forming AD was identified on the ventral surface of the paired somites at the 6-somite stage, appearing almost simultaneously from the cranial to caudal somite regions. After the 8-somite stage, the AV was formed by transformation of one of the caudal plexuses spreading to the area vasculosa. In the 9-somite stage, the angioblastic cords of the VC appeared on the dorsal side of the mesoderm in the same manner as for other ventral vessels. This finding differs from the statement of a previous author that the VCis formed by longitudinal anastomosis of intersegmental diverticula of the AD. PMID:7340557

Hirakow, R; Hiruma, T

1981-01-01

318

Mechanisms of superoxide production in human blood vessels: relationship to endothelial dysfunction, clinical and genetic risk factors.  

PubMed

Common vascular disease states including diabetes, hypertension and atherosclerosis are associated with endothelial dysfunction, characterised by reduced bioactivity of nitric oxide (NO). Loss of the vasculoprotective effects of NO contributes to disease progression, but the mechanisms underlying endothelial dysfunction remain unclear. Increased superoxide production in animal models of vascular disease contributes to reduced NO bioavailability, endothelial dysfunction and oxidative stress. In human blood vessels, the NAD(P)H oxidase system is the principal source of superoxide, and is functionally related to clinical risk factors and systemic endothelial dysfunction. Furthermore, the C242T polymorphism in the NAD(P)H oxidase p22phox subunit is associated with significantly reduced superoxide production in patients carrying the 242T allele, suggesting a role for genetic variation in modulating vascular superoxide production. In vessels from patients with diabetes mellitus, endothelial dysfunction, NAD(P)H oxidase activity and protein subunits are significantly increased compared with matched non-diabetic vessels. Furthermore, the vascular endothelium in diabetic vessels is a net source of superoxide rather than NO production, due to dysfunction of endothelial NO synthase (eNOS). This deficit is dependent on the eNOS cofactor, tetrahydrobiopterin, and is in part mediated by protein kinase C signalling. These studies suggest an important role for both the NAD(P)H oxidases and endothelial NOS in the increased vascular superoxide production and endothelial dysfunction in human vascular disease states. PMID:12512689

Channon, K M; Guzik, T J

2002-12-01

319

Painting blood vessels and atherosclerotic plaques with an adhesive drug depot  

E-print Network

The treatment of diseased vasculature remains challenging, in part because of the difficulty in implanting drug-eluting devices without subjecting vessels to damaging mechanical forces. Implanting materials using adhesive ...

Kastrup, Christian J.

320

Blood vessel segmentation and width estimation in ultra-wide field scanning laser ophthalmoscopy  

PubMed Central

Features of the retinal vasculature, such as vessel widths, are considered biomarkers for systemic disease. The aim of this work is to present a supervised approach to vessel segmentation in ultra-wide field of view scanning laser ophthalmoscope (UWFoV SLO) images and to evaluate its performance in terms of segmentation and vessel width estimation accuracy. The results of the proposed method are compared with ground truth measurements from human observers and with existing state-of-the-art techniques developed for fundus camera images that we optimized for UWFoV SLO images. Our algorithm is based on multi-scale matched filters, a neural network classifier and hysteresis thresholding. After spline-based refinement of the detected vessel contours, the vessel widths are estimated from the binary maps. Such analysis is performed on SLO images for the first time. The proposed method achieves the best results, both in vessel segmentation and in width estimation, in comparison to other automatic techniques. PMID:25574441

Pellegrini, Enrico; Robertson, Gavin; Trucco, Emanuele; MacGillivray, Tom J.; Lupascu, Carmen; van Hemert, Jano; Williams, Michelle C.; Newby, David E.; van Beek, Edwin JR; Houston, Graeme

2014-01-01

321

The effects of healthy aging on intracerebral blood vessels visualized by magnetic resonance angiography  

PubMed Central

Histological and magnetic resonance imaging studies have demonstrated that age-associated alterations of the human brain may be at least partially related to vascular alterations. Relatively little information has been published on vascular changes associated with healthy aging, however. The study presented in this paper examined vessels segmented from standardized, high-resolution, magnetic resonance angiograms (MRA) of 100 healthy volunteers (50 males, 50 females), aged 18-74, without hypertension or other disease likely to affect the vasculature. The subject sample was divided into 5 age groups (n=20/group) with gender equally distributed per group. The anterior cerebral, both middle cerebral, and the posterior circulations were examined for vessel number, vessel radius, and vessel tortuosity. Males exhibited larger vessel radii regardless of age and across all anatomical regions. Both males and females displayed a lower number of MRA-discernible vessels with age, most marked in the posterior circulation. Age-associated tortuosity increases were relatively mild. Our multi-modal image database has been made publicly available for use by other investigators. PMID:18471935

Bullitt, Elizabeth; Zeng, Donglin; Mortamet, Benedicte; Ghosh, Arpita; Aylward, Stephen R.; Lin, Weili; Marks, Bonita L.; Smith, Keith

2010-01-01

322

Dynamic monitoring of platelet deposition on severely damaged vessel wall in flowing blood. Effects of different stenoses on thrombus growth  

SciTech Connect

The formation of an arterial thrombus is a dynamic process that depends upon the characteristics of blood flow, the triggering substrate, and the blood components. We have developed and characterized a sensitive and specific computer-assisted nuclear scintigraphic method to study the dynamics of platelet deposition on severely damaged vessels both in vitro and in vivo in nonstenotic and stenotic flow conditions. Heparinized pig blood with Indium-111-labeled platelets was perfused for 50 minutes. Method variability in both static and flowing conditions was evaluated by Indium-111-labeled transferrin and Indium-111-labeled platelets. Positive scintigrams were obtained mainly in the presence of severe high grade stenoses on a thrombogenic substrate. Since the method is highly sensitive, computer-assisted axial dependence analysis was performed on the scintigraphic images to locate the thrombotic accumulation with respect to the area of the stenosis and to monitor the dynamic changes in platelet accumulation over time. Both in vitro and in vivo the highest level of platelet deposition occurred at the apex of the 80% stenosis, where embolization could be usually detected after 30 minutes of perfusion. This study is the first to assess the dynamics of thrombus growth in nonparallel flow streamlines such as are encountered in stenotic vessels. This method provides a new experimental tool with which to study factors affecting thrombus formation and stability.

Lassila, R.; Badimon, J.J.; Vallabhajosula, S.; Badimon, L. (Mount Sinai Medical Center, NY (USA))

1990-03-01

323

Coronary vessel trees from 3D imagery: A topological approach  

PubMed Central

We propose a simple method for reconstructing vascular trees from 3D images. Our algorithm extracts persistent maxima of the intensity on all axis-aligned 2D slices of the input image. The maxima concentrate along 1D intensity ridges, in particular along blood vessels. We build a forest connecting the persistent maxima with short edges. The forest tends to approximate the blood vessels present in the image, but also contains numerous spurious features and often fails to connect segments belonging to one vessel in low contrast areas. We improve the forest by applying simple geometric filters that trim short branches, fill gaps in blood vessels and remove spurious branches from the vascular tree to be extracted. Experiments show that our technique can be applied to extract coronary trees from heart CT scans. PMID:16798058

Szymczak, Andrzej; Stillman, Arthur; Tannenbaum, Allen; Mischaikow, Konstantin

2013-01-01

324

Enhanced nestin expression and small blood vessels in human pituitary adenomas.  

PubMed

The role of angiogenesis in human pituitary tumor progression is questioned. Our aim was to characterize the morphologic changes that occur in the vasculature of pituitary adenomas, in correlation with the expression of nestin, a protein found in endothelial cells of newly formed vessels of developing organs. We also evaluated the relation of angiogenic markers and nestin with Ki-67 index. Immunohistochemical studies were performed on paraffin embedded samples of 47 pituitary adenomas and six normal pituitaries. We determined microvessel density (number of CD31+ or CD34+ vessels per square millimetre), vascular area (cumulative area occupied by vessels), average vessel size, and further classified vessels as small (< 100 ?m2) or large (> 100 ?m2). We correlated the above parameters with nestin expression and Ki-67 index. Lower vascular area compared to normal tissue was found in adenomas (p < 0.05). Interestingly, pituitary adenomas had significantly more small vessels than control pituitaries (p < 0.04 for CD31 and CD34). In tumors many capillaries were positive for nestin, while scarce staining was detected in controls, so that nestin positive area was significantly higher in tumors. Furthermore, nestin area correlated positively with the % of small vessels. Ki-67 correlated neither with vascular area nor with nestin expression. In human pituitary tumors there was a predominance of small capillaries in correlation with increased expression of the progenitor marker nestin. We suggest that angiogenesis is an active process in these tumors, in spite of their low total vascular area when compared to normal pituitaries. PMID:22886682

Perez-Millan, Mara Ins; Berner, Silvia Ins; Luque, Guillermina Mara; De Bonis, Cristian; Sevlever, Gustavo; Becu-Villalobos, Damasia; Cristina, Carolina

2013-09-01

325

Multi-scale finite element analyses for stress and strain evaluations of braid fibril artificial blood vessel and smooth muscle cell.  

PubMed

In this study, we developed a multi-scale finite element (FE) analysis code to obtain the stress and strain that occurred in the smooth muscle cell (SMC) at micro-scale, which was seeded in the real fabricated braid fibril artificial blood vessel. This FE code can predict the dynamic response of stress under the blood pressure loading. We try to establish a computer-aided engineering (CAE)-driven scaffold design technique for the blood vessel regeneration. Until now, there occurred the great progresses for the endothelial cell activation and intima layer regeneration in the blood vessel regeneration study. However, there remains the difficulty of the SMC activation and media layer regeneration. Therefore, many researchers are now studying to elucidate the fundamental mechanism of SMC activation and media layer regeneration by using the biomechanical technique. As the numerical tool, we used the dynamic-explicit FE code PAM-CRASH, ESI Ltd. For the material models, the nonlinear viscoelastic constitutive law was adapted for the human blood vessel, SMC and the extra-cellular matrix, and the elastic law for the polyglycolic acid (PGA) fiber. Through macro-FE and micro-FE analyses of fabricated braid fibril tubes by using PGA fiber under the combined conditions of the orientation angle and the pitch of fiber, we searched an appropriate structure for the stress stimulation for SMC functionalization. Objectives of this study are indicated as follows: 1. to analyze the stress and strain of the human blood vessel and SMC, and 2. to calculate stress and strain of the real fabricated braid fibril artificial blood vessel and SMC to search an appropriate PGA fiber structure under combined conditions of PGA fiber numbers, 12 and 24, and the helical orientation angles of fiber, 15, 30, 45, 60, and 75 degrees. Finally, we found a braid fibril tube, which has an angle of 15 degree and 12 PGA fibers, as a most appropriate artificial blood vessel for SMC functionalization. PMID:24599892

Nakamachi, Eiji; Uchida, Takahiro; Kuramae, Hiroyuki; Morita, Yusuke

2014-08-01

326

Effect of Antiprogesterone RU486 on VEGF Expression and Blood Vessel Remodeling on Ovarian Follicles before Ovulation  

PubMed Central

Background The success of ovarian follicle growth and ovulation is strictly related to the development of an adequate blood vessel network required to sustain the proliferative and endocrine functions of the follicular cells. Even if the Vascular Endothelial Growth Factor (VEGF) drives angiogenesis before ovulation, the local role exerted by Progesterone (P4) remains to be clarified, in particular when its concentration rapidly increases before ovulation. Aim This in vivo study was designed to clarify the effect promoted by a P4 receptor antagonist, RU486, on VEGF expression and follicular angiogenesis before ovulation, in particular, during the transition from pre to periovulatory follicles induced by human Chorionic Gonadotropins (hCG) administration. Material and Methods Preovulatory follicle growth and ovulation were pharmacologically induced in prepubertal gilts by combining equine Chorionic Gonadotropins (eCG) and hCG used in the presence or absence of RU486. The effects on VEGF expression were analyzed using biochemical and immunohistochemical studies, either on granulosa or on theca layers of follicles isolated few hours before ovulation. This angiogenic factor was also correlated to follicular morphology and to blood vessels architecture. Results and Conclusions VEGF production, blood vessel network and follicle remodeling were impaired by RU486 treatment, even if the cause-effect correlation remains to be clarified. The P4 antagonist strongly down-regulated theca VEGF expression, thus, preventing most of the angiogenic follicle response induced by hCG. RU486-treated follicles displayed a reduced vascular area, a lower rate of endothelial cell proliferation and a reduced recruitment of perivascular mural cells. These data provide important insights on the biological role of RU486 and, indirectly, on steroid hormones during periovulatory follicular phase. In addition, an in vivo model is proposed to evaluate how periovulatory follicular angiogenesis may affect the functionality of the corpus luteum (CL) and the success of pregnancy. PMID:24756033

Berardinelli, Paolo; Russo, Valentina; Bernab, Nicola; Di Giacinto, Oriana; Mattioli, Mauro; Barboni, Barbara

2014-01-01

327

Expression and functional significance of NADPH oxidase 5 (Nox5) and its splice variants in human blood vessels  

PubMed Central

The expression and functional significance of NADPH oxidase 5 (Nox5) and its five isoforms in vascular cells is poorly understood. The goal of this study was to determine whether Nox5-?, -?, -?, -?, and -? (short) are expressed in human blood vessels and evaluate their respective functions. Nox5 mRNA and protein were detected in human blood vessels, cultured human vascular smooth muscle (HVSMC) and endothelium, but not fibroblasts. The most abundant isoforms were ? and ?, whereas ? and ? were not detected. Nox5-? and -? produced reactive oxygen species (ROS), but -?, -?, and -? were not catalytically active. Coexpression of the active Nox5 isoforms with inactive Nox5 variants suppressed ROS production, and coimmunoprecipitation revealed that Nox5-? binds the inactive ? variant, which may account for reduced ROS production. In HVSMC, angiotensin II, endothelin-1 and TNF-? increased endogenous Nox5 mRNA levels, while adenovirus-mediated overexpression of Nox5 promoted p38 MAPK, JAK2, JNK, and ERK1/2 phosphorylation in endothelial cells (EC), but only increased ERK1/2 phosphorylation in HVSMC. At higher levels of Nox5, there was evidence of increased apoptosis in EC, but not in HVSMC, as detected by the presence of cleaved caspase-3 and cleaved poly(ADP-ribose)polymerase. Although catalytically inactive, Nox5-? potently activated ERK in HVSMC, and increased expression of Nox5-? promoted HVSMC proliferation. Nox5 is expressed in human blood vessels. The Nox5-? and -? splice variants are the major isoforms that are expressed and the only variants capable of ROS production. Nox5-? can inhibit Nox5 activity and activate ERK and HVSMC proliferation. PMID:22427510

Pandey, Deepesh; Patel, Anand; Patel, Vijay; Chen, Feng; Qian, Jin; Wang, Yusi; Barman, Scott A.; Venema, Richard C.; Stepp, David W.; Daniel Rudic, R.

2012-01-01

328

Expression and functional significance of NADPH oxidase 5 (Nox5) and its splice variants in human blood vessels.  

PubMed

The expression and functional significance of NADPH oxidase 5 (Nox5) and its five isoforms in vascular cells is poorly understood. The goal of this study was to determine whether Nox5-?, -?, -?, -?, and -? (short) are expressed in human blood vessels and evaluate their respective functions. Nox5 mRNA and protein were detected in human blood vessels, cultured human vascular smooth muscle (HVSMC) and endothelium, but not fibroblasts. The most abundant isoforms were ? and ?, whereas ? and ? were not detected. Nox5-? and -? produced reactive oxygen species (ROS), but -?, -?, and -? were not catalytically active. Coexpression of the active Nox5 isoforms with inactive Nox5 variants suppressed ROS production, and coimmunoprecipitation revealed that Nox5-? binds the inactive ? variant, which may account for reduced ROS production. In HVSMC, angiotensin II, endothelin-1 and TNF-? increased endogenous Nox5 mRNA levels, while adenovirus-mediated overexpression of Nox5 promoted p38 MAPK, JAK2, JNK, and ERK1/2 phosphorylation in endothelial cells (EC), but only increased ERK1/2 phosphorylation in HVSMC. At higher levels of Nox5, there was evidence of increased apoptosis in EC, but not in HVSMC, as detected by the presence of cleaved caspase-3 and cleaved poly(ADP-ribose)polymerase. Although catalytically inactive, Nox5-? potently activated ERK in HVSMC, and increased expression of Nox5-? promoted HVSMC proliferation. Nox5 is expressed in human blood vessels. The Nox5-? and -? splice variants are the major isoforms that are expressed and the only variants capable of ROS production. Nox5-? can inhibit Nox5 activity and activate ERK and HVSMC proliferation. PMID:22427510

Pandey, Deepesh; Patel, Anand; Patel, Vijay; Chen, Feng; Qian, Jin; Wang, Yusi; Barman, Scott A; Venema, Richard C; Stepp, David W; Rudic, R Daniel; Fulton, David J R

2012-05-15

329

Inflammation-inducible type 2 deiodinase expression in the leptomeninges, choroid plexus, and at brain blood vessels in male rodents.  

PubMed

Thyroid hormone regulates immune functions and has antiinflammatory effects. In promoter assays, the thyroid hormone-activating enzyme, type 2 deiodinase (D2), is highly inducible by the inflammatory transcription factor nuclear factor-? B (NF-?B), but it is unknown whether D2 is induced in a similar fashion in vivo during inflammation. We first reexamined the effect of bacterial lipopolysaccharide (LPS) on D2 expression and NF-?B activation in the rat and mouse brain using in situ hybridization. In rats, LPS induced very robust D2 expression in normally non-D2-expressing cells in the leptomeninges, adjacent brain blood vessels, and the choroid plexus. These cells were vimentin-positive fibroblasts and expressed the NF-?B activation marker, inhibitor ? B-? mRNA, at 2 hours after injection, before the increase in D2 mRNA. In mice, LPS induced intense D2 expression in the choroid plexus but not in leptomeninges, with an early expression peak at 2 hours. Moderate D2 expression along numerous brain blood vessels appeared later. D2 and NF-?B activation was induced in tanycytes in both species but with a different time course. Enzymatic assays from leptomeningeal and choroid plexus samples revealed exceptionally high D2 activity in LPS-treated rats and Syrian hamsters and moderate but significant increases in mice. These data demonstrate the cell type-specific, highly inducible nature of D2 expression by inflammation, and NF-?B as a possible initiating factor, but also warrant attention for species differences. The results suggest that D2-mediated T? production by fibroblasts regulate local inflammatory actions in the leptomeninges, choroid plexus and brain blood vessels, and perhaps also in other organs. PMID:24601886

Wittmann, Gbor; Harney, John W; Singru, Praful S; Nouriel, Shira S; Reed Larsen, P; Lechan, Ronald M

2014-05-01

330

Branches of the intracavernous internal carotid artery and the blood supply of the intracavernous cranial nerves.  

PubMed

With the increasing frequency of surgical operations to the cavernous sinus greater knowledge of the microanatomy of the cavernous sinus has become necessary. The most frequently seen complications during cavernous sinus surgery involve impairment of cranial nerves. This can occur due to direct damage or ischemia. For these reasons, it is important to know the arterial supplies to the cranial nerves in the cavernous sinus and the anatomy of these branches as well. 15 formaline fixed adult cadavers were used in this study. Before the dissections, the internal carotid artery and vertebral artery were filled with coloured latex on both sides. In this report, the intracavernous branches of internal carotid artery (I.I.C.A.) were identified based on the principles of Nomina Anatomica (1989) and compared with others. In our study we found that the segment of the abducens nerve which lies in Dorello's channel was supplied by the meningeal branch; from the point at which it pierces the cerebellar tentorium, the trochlear nerve is supplied by the tentorial cerebellar artery; the posterior cerebellar artery supplies the proximal segment of the oculomotor nerve that proceeds to the oculomotor triangle. Except for these, all the cranial nerves that were located on the lateral wall of the sinus cavernosus are supplied by the tentorial marginal branch and the branches of the lateral trunk. PMID:9728276

Tekdemir, I; Tccar, E; Cubuk, H E; Ersoy, M; Elhan, A; Deda, H

1998-08-01

331

Immuno- and Enzyme-histochemistry of HRP for Demonstration of Blood Vessel Permeability in Mouse Thymic Tissues by In Vivo Cryotechnique  

PubMed Central

It is difficult to understand the in vivo permeability of thymic blood vessels, but in vivo cryotechnique (IVCT) is useful to capture dynamic blood ?ow conditions. We injected various concentrations of horseradish peroxidase (HRP) with or without quantum dots into anesthetized mice via left ventricles to examine architectures of thymic blood vessels and their permeability at different time intervals. At 30 sec after HRP (100 mg/ml) injection, enzyme reaction products were weakly detected in interstitium around some thick blood vessels of corticomedullary boundary areas, but within capillaries of cortical areas. At 1 and 3 min, they were more widely detected in interstitium around all thick blood vessels of the boundary areas. At 10 min, they were diffusely detected throughout interstitium of cortical areas, and more densely seen in medullary areas. At 15 min, however, they were uniformly detected throughout interstitium outside blood vessels. At 30 min, phagocytosis of HRP by macrophages was scattered throughout the interstitium, which was accompanied by decrease of HRP reaction intensity in interstitial matrices. Thus, time-dependent HRP distributions in living mice indicate that molecular permeability and diffusion depend on different areas of thymic tissues, resulting from topographic variations of local interstitial flow starting from corticomedullary areas.

Wu, Bao; Ohno, Nobuhiko; Saitoh, Yurika; Bai, Yuqin; Huang, Zheng; Terada, Nobuo; Ohno, Shinichi

2014-01-01

332

Neurogenic regulation of cochlear blood flow occurs along the basilar artery, the anterior inferior cerebellar artery and at branch points of the spiral modiolar artery.  

PubMed

The cochlea receives its main blood supply from the basilar artery via the anterior inferior cerebellar artery and the spiral modiolar artery. Morphologic studies have shown sympathetic innervation along the spiral modiolar artery of the gerbil and the guinea pig and functional studies in the isolated in vitro superfused spiral modiolar artery of the gerbil have demonstrated norepinephrine-induced vasoconstrictions via alpha(1A)-adrenergic receptors. It is current unclear whether the sympathetic innervation is physiologically relevant. Stimulation of sympathetic ganglia in guinea pigs has been shown to alter cochlear blood flow in situ. Whether these changes originated from local or more systemic changes in the vascular diameter remained uncertain. The goal of the present study was to demonstrate the presence or absence of neurogenic changes in the diameter of the isolated in vitro superfused spiral modiolar artery, anterior inferior cerebellar artery and basilar artery from the gerbil and the guinea pig. Vascular diameter was monitored by videomicroscopy. Electric field stimulation was used to elicit neurotransmitter release. A reversible inhibitory effect of 10(-6) M tetrodotoxin was taken as criterion to discriminate between neurogenic and myogenic changes in vascular diameter. Mesentery arteries of comparable diameter, which are known to respond with a neurogenic vasoconstriction to electric field stimulation, served as controls. Basilar artery, anterior inferior cerebellar artery, spiral modiolar artery and mesentery arteries constricted in response to electric field stimulation. No dilations were observed. Myogenic and neurogenic vasoconstrictions were observed in all vessels. These observations suggest that the sympathetic innervation of the basilar artery, the anterior inferior cerebellar artery and branch points of the spiral modiolar artery is involved in a physiologically relevant control of the vascular diameter in the gerbil and the guinea pig. PMID:16054311

Wangemann, Philine; Wonneberger, Kai

2005-11-01

333

Angiogenesis in the developing spinal cord: blood vessel exclusion from neural progenitor region is mediated by VEGF and its antagonists.  

PubMed

Blood vessels in the central nervous system supply a considerable amount of oxygen via intricate vascular networks. We studied how the initial vasculature of the spinal cord is formed in avian (chicken and quail) embryos. Vascular formation in the spinal cord starts by the ingression of intra-neural vascular plexus (INVP) from the peri-neural vascular plexus (PNVP) that envelops the neural tube. At the ventral region of the PNVP, the INVP grows dorsally in the neural tube, and we observed that these vessels followed the defined path at the interface between the medially positioned and undifferentiated neural progenitor zone and the laterally positioned differentiated zone. When the interface between these two zones was experimentally displaced, INVP faithfully followed a newly formed interface, suggesting that the growth path of the INVP is determined by surrounding neural cells. The progenitor zone expressed mRNA of vascular endothelial growth factor-A whereas its receptor VEGFR2 and FLT-1 (VEGFR1), a decoy for VEGF, were expressed in INVP. By manipulating the neural tube with either VEGF or the soluble form of FLT-1, we found that INVP grew in a VEGF-dependent manner, where VEGF signals appear to be fine-tuned by counteractions with anti-angiogenic activities including FLT-1 and possibly semaphorins. These results suggest that the stereotypic patterning of early INVP is achieved by interactions between these vessels and their surrounding neural cells, where VEGF and its antagonists play important roles. PMID:25585380

Takahashi, Teruaki; Takase, Yuta; Yoshino, Takashi; Saito, Daisuke; Tadokoro, Ryosuke; Takahashi, Yoshiko

2015-01-01

334

Angiogenesis in the Developing Spinal Cord: Blood Vessel Exclusion from Neural Progenitor Region Is Mediated by VEGF and Its Antagonists  

PubMed Central

Blood vessels in the central nervous system supply a considerable amount of oxygen via intricate vascular networks. We studied how the initial vasculature of the spinal cord is formed in avian (chicken and quail) embryos. Vascular formation in the spinal cord starts by the ingression of intra-neural vascular plexus (INVP) from the peri-neural vascular plexus (PNVP) that envelops the neural tube. At the ventral region of the PNVP, the INVP grows dorsally in the neural tube, and we observed that these vessels followed the defined path at the interface between the medially positioned and undifferentiated neural progenitor zone and the laterally positioned differentiated zone. When the interface between these two zones was experimentally displaced, INVP faithfully followed a newly formed interface, suggesting that the growth path of the INVP is determined by surrounding neural cells. The progenitor zone expressed mRNA of vascular endothelial growth factor-A whereas its receptor VEGFR2 and FLT-1 (VEGFR1), a decoy for VEGF, were expressed in INVP. By manipulating the neural tube with either VEGF or the soluble form of FLT-1, we found that INVP grew in a VEGF-dependent manner, where VEGF signals appear to be fine-tuned by counteractions with anti-angiogenic activities including FLT-1 and possibly semaphorins. These results suggest that the stereotypic patterning of early INVP is achieved by interactions between these vessels and their surrounding neural cells, where VEGF and its antagonists play important roles. PMID:25585380

Takahashi, Teruaki; Takase, Yuta; Yoshino, Takashi; Saito, Daisuke; Tadokoro, Ryosuke; Takahashi, Yoshiko

2015-01-01

335

MRI measurement of oxygen extraction fraction, mean vessel size and cerebral blood volume using serial hyperoxia and hypercapnia.  

PubMed

Functional magnetic resonance imaging measures signal increases arising from a variety of interrelated effects and physiological sources. Recently there has been some success in disentangling this signal in order to quantify baseline physiological parameters, including the resting oxygen extraction fraction (OEF), cerebral blood volume (CBV) and mean vessel size. However, due to the complicated nature of the signal, each of these methods relies on certain physiological assumptions to derive a solution. In this work we present a framework for the simultaneous, voxelwise measurement of these three parameters. The proposed method removes the assumption of a fixed vessel size from the quantification of OEF and CBV, while simultaneously removing the need for an assumed OEF in the calculation of vessel size. The new framework is explored through simulations and validated with a pilot study in healthy volunteers. The MRI protocol uses a combined hyperoxia and hypercapnia paradigm with a modified spin labelling sequence collecting multi-slice gradient echo and spin echo data. PMID:24531048

Germuska, Michael; Bulte, Daniel P

2014-05-15

336

Medical Tests and Procedures for Finding and Treating Heart and Blood Vessel Disease  

MedlinePLUS

... Angioplasty may be done during a heart attack. Ankle brachial index A test called an ankle brachial (BRAY-kee-al) index or ABI is ... to compare the blood pressure in the patients ankles to the blood pressure in the patients arms. ...

337

Biophysical Properties of Scaffolds Modulate Human Blood Vessel Formation from Circulating Endothelial Colony-Forming Cells  

NASA Astrophysics Data System (ADS)

A functional vascular system forms early in development and is continually remodeled throughout the life of the organism. Impairment to the regeneration or repair of this system leads to tissue ischemia, dysfunction, and disease. The process of vascular formation and remodeling is complex, relying on local microenvironmental cues, cytokine signaling, and multiple cell types to function properly. Tissue engineering strategies have attempted to exploit these mechanisms to develop functional vascular networks for the generation of artificial tissues and therapeutic strategies to restore tissue homeostasis. The success of these strategies requires the isolation of appropriate progenitor cell sources which are straightforward to obtain, display high proliferative potential, and demonstrate an ability to form functional vessels. Several populations are of interest including endothelial colony-forming cells, a subpopulation of endothelial progenitor cells. Additionally, the development of scaffolds to deliver and support progenitor cell survival and function is crucial for the formation of functional vascular networks. The composition and biophysical properties of these scaffolds have been shown to modulate endothelial cell behavior and vessel formation. However, further investigation is needed to better understand how these mechanical properties and biophysical properties impact vessel formation. Additionally, several other cell populations are involved in neoangiogenesis and formation of tissue parenchyma and an understanding of the potential impact of these cell populations on the biophysical properties of scaffolds will also be needed to advance these strategies. This chapter examines how the biophysical properties of matrix scaffolds can influence vessel formation and remodeling and, in particular, the impact on in vivo human endothelial progenitor cell vessel formation.

Critser, Paul J.; Yoder, Mervin C.

338

Forkhead Box M1 Transcriptional Factor is Required for Smooth Muscle Cells during Embryonic Development of Blood Vessels and Esophagus  

PubMed Central

The Forkhead Box m1 (Foxm1 or Foxm1b) transcription factor (previously called HFH-11B, Trident, Win, or MPP2) is expressed in a variety of tissues during embryogenesis, including vascular, airway and intestinal smooth muscle cells (SMC). Although global deletion of Foxm1 in Foxm1?/? mice is lethal in the embryonic period due to multiple abnormalities in the liver, heart and lung, the specific role of Foxm1 in SMC remains unknown. In the present study, Foxm1 was deleted conditionally in the developing SMC (smFoxm1?/? mice). The majority of smFoxm1?/? mice died immediately after birth due to severe pulmonary hemorrhage, and structural defects in arterial wall and esophagus. Although Foxm1 deletion did not influence SMC differentiation, decreased proliferation of SMC was found in smFoxm1?/? blood vessels and esophagus. Depletion of Foxm1 in cultured SMC caused G2 arrest and decreased numbers of cells undergoing mitosis. Foxm1-deficiency in vitro and in vivo was associated with reduced expression of cell cycle regulatory genes, including cyclin B1, Cdk1-activator Cdc25b phosphatase, Polo-like 1 and JNK1 kinases, and cMyc transcription factor. Foxm1 is critical for proliferation of smooth muscle cells and is required for proper embryonic development of blood vessels and esophagus. PMID:19835856

Ustiyan, Vladimir; Wang, I-Ching; Ren, Xiaomeng; Zhang, Yufang; Snyder, Jonathan; Xu, Yan; Wert, Susan E.; Lessard, James L.; Kalin, Tanya V.; Kalinichenko, Vladimir V.

2009-01-01

339

CO2 laser soldering of arteriotomy incisions in blood vessels of rats using a temperature-controlled fiber optic system  

NASA Astrophysics Data System (ADS)

Background and objectives: Conventional methods for microvascular anastomosis are normally based on suturing, using special thin nylon sutures. These methods suffer from major drawbacks, which include: anastomosis, which is not watertight, and sutures or clips that cause an inflammatory response. In order to obtain better results, we introduced a procedure based on CO2 laser soldering. We tested the system on arteriotomy incisions in rat blood vessels, in vivo. Materials and methods: We used a fiber optic based laser soldering system, with a temperature control capability. Arteriotomy incisions of lengths 4+/-1mm were performed on the femoral arteries of 48 wistar rats: 24 rats in the control group (suture) and 24 rats in the test group (laser soldering). We conducted two follow-up periods: 7 days and 21 days after the surgical procedure, for each group. Flow tests and histology examination were done in order to evaluate the quality of the procedures. Results: The patency rate was 84% for both groups, soldered and sutured. The sutured group showed a significant foreign body reaction (p < 0.05), which was not observed in the soldered group. We found no evidence of thermal damage in the soldered blood vessels. Conclusions: We can conclude that laser soldering is a less traumatic procedure, compared with the conventional suturing technique. It is potentially a faster technique and easier to master.

Leshem, David; Vasilyev, Tamar; Ravid, Avi; Gat, Andrea; Kariv, Naam; Katzir, Abraham; Gur, Eyal

2003-06-01

340

[Changes in ligated blood-vessel stumps during abdominal hysterectomy including the removal of the adnexa uteri].  

PubMed

Histological changes of ligated blood vessels were studied on 30 women of 41 to 57 years who had been selected according to certain criteria. For this purpose we usually resected the ligg. suspensoria ovarii, parts of the mesosalpinx, lig. latum and rotundum, the vasa uterina, segments of the basale parametrium the plexus vesico-vaginalis and others after 15 to 25 minutes. The abdominal hysterectomy was in most cases indicated due to uterus myomatosus. The histological examinations showed that, in spite of the ligation of the vessels the organism protects itself by forming a closing thrombus preventing a hemorrhage threatening life as well as a secondary hemorrhage at a later stage due to demarcation of the distal stump end. The occlusion consist of merged thrombocytes, coagulated fibrin and other blood elements; the lesion of the endothelial cells isvery important. Proximal, to the centre, the intravasal mutations decrease rapidly, the lumen is in most of the cases empty. Only in 16% of the lumina of arteries or arterioles and in 20% of the veins there were no hemostatic plugs found. The problem of hemostasis during the gynecological operation is only being touched upon, possible complications due to circulation and perfusion lesions are mentioned. A pathological extent of the coagulation in small pelvis is likely to be the reason for an embolism. PMID:961167

Slunsky, R

1976-01-01

341

The hepatitis C virus internal ribosome entry site facilitates efficient protein synthesis in blood vessel endothelium during tumour angiogenesis.  

PubMed

The development of gene delivery systems for therapeutic use involves vectors (often retrovirus or adenovirus) which typically encode one target protein, but the use of internal ribosome entry sites (IRES) can confer the ability to express more than one protein from bi- or polycistronic mRNAs. IRES elements can display tissue-specific expression, so it is necessary to determine suitable IRES for specific clinical applicability. Blood vessel endothelial cells are important clinically since many different conditions involve neo-vascularisation (angiogenesis). We have demonstrated that the viral hepatitis C IRES element is a powerful mediator of protein synthesis in angiogenesis, such as found in solid tumours. Homologous recombination was used to introduce IRES-lacZ sequences into the Lmo2 gene, which is expressed in endothelial cells. beta-Galactosidase expression was determined during vascular remodelling in mouse embryos and in sprouting endothelium during growth of solid tumours, and showed that the hepatitis C IRES is used efficiently for protein synthesis in endothelial cells. This IRES element can provide the means to express two or more therapeutic genes in blood vessel endothelium in clinical conditions, such as cancer, which depend on angiogenesis. PMID:12682381

Chung, Grace T Y; Yamada, Yoshihiro; Pannell, Richard; Forster, Alan; Rabbitts, Terence H

2003-04-15

342

Cancer cell-associated MT1-MMP promotes blood vessel invasion and distant metastasis in triple-negative mammary tumors.  

PubMed

Functional roles for the cancer cell-associated membrane type I matrix metalloproteinase (MT1-MMP) during early steps of the metastatic cascade in primary tumors remain unresolved. In an effort to determine its significance, we determined the in vivo effects of RNAi-mediated downregulation in mammary cancer cells on the migration, blood and lymphatic vessel invasion (LVI), and lymph node and lung metastasis. We also correlated the expression of cancer cell MT1-MMP with blood vessel invasion (BVI) in 102 breast cancer biopsies. MT1-MMP downregulation in cancer cells decreased lung metastasis without affecting primary tumor growth. The inhibition of lung metastasis correlated with reduced cancer cell migration and BVI. Furthermore, cancer cell-expressed MT1-MMP upregulated the expression of MT1-MMP in vascular endothelial cells, but did not affect MT1-MMP expression in lymphatic endothelial cells, LVI, or lymph node metastasis. Of clinical importance, we observed that elevated MT1-MMP expression correlated with BVI in biopsies from triple-negative breast cancers (TNBC), which have a poor prognosis and high incidence of distant metastasis, relative to other breast cancer subtypes. Together, our findings established that MT1-MMP activity in breast tumors is essential for BVI, but not LVI, and that MT1-MMP should be further explored as a predictor and therapeutic target of hematogenous metastasis in TNBC patients. PMID:21571860

Perentes, Jean Y; Kirkpatrick, Nathaniel D; Nagano, Satoshi; Smith, Eve Y; Shaver, Christine M; Sgroi, Dennis; Garkavtsev, Igor; Munn, Lance L; Jain, Rakesh K; Boucher, Yves

2011-07-01

343

Heparinized PLLA/PLCL nanofibrous scaffold for potential engineering of small-diameter blood vessel: Tunable elasticity and anticoagulation property.  

PubMed

The success of tissue engineered vascular grafts depends greatly on the synthetic tubular scaffold, which can mimic the architecture, mechanical, and anticoagulation properties of native blood vessels. In this study, small-diameter tubular scaffolds were fabricated with different weight ratios of poly(l-lactic acid) (PLLA) and poly(l-lactide-co-?-caprolactone) (PLCL) by means of thermally induced phase separation technique. To improve the anticoagulation property of materials, heparin was covalently linked to the tubular scaffolds by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide coupling chemistry. The as-prepared PLLA/PLCL scaffolds retained microporous nanofibrous structure as observed in the neat PLLA scaffolds, and their structural and mechanical properties can be fine-tuned by changing the ratio of two components. The scaffold containing 60% PLCL content was found to be the most promising scaffold for engineering small-diameter blood vessel in terms of elastic properties and structural integrity. The heparinized scaffolds showed higher hydrophilicity, lower protein adsorption ability, and better in vitro anticoagulation property than their untreated counterparts. Pig iliac endothelial cells seeded on the heparinized scaffold showed good cellular attachment, spreading, proliferation, and phenotypic maintenance. Furthermore, the heparinized scaffolds exhibited neovascularization after subcutaneous implantation into the New Zealand white rabbits for 1 and 2 months. Taken together, the heparinized PLLA/PLCL nanofibrous scaffolds have the great potential for vascular tissue engineering application. 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1784-1797, 2015. PMID:25196988

Wang, Weizhong; Hu, Jinwei; He, Chuanglong; Nie, Wei; Feng, Wei; Qiu, Kexin; Zhou, Xiaojun; Gao, Yu; Wang, Guoqing

2015-05-01

344

Computational blood flow and vessel wall modeling in a CT-based thoracic aorta after stent-graft implantation  

NASA Astrophysics Data System (ADS)

Abnormal blood flow conditions and structural fatigue within stented vessels may lead to undesired failure causing death to the patient. Image-based computational modeling provides a physical and realistic insight into the patientspecific biomechanics and enables accurate predictive simulations of development, growth and failure of cardiovascular diseases as well as associated risks. Controlling the efficiency of an endovascular treatment is necessary for the evaluation of potential complications and predictions on the assessment of the pathological state. In this paper we investigate the effects of stent-graft implantation on the biomechanics in a patient-specific thoracic aortic model. The patient geometry and the implanted stent-graft are obtained from morphological data based on a CT scan performed during a controlling routine. Computational fluid dynamics (CFD) and computational structure mechanics (CSM) simulations are conducted based on the finite volume method (FVM) and on the finite element method (FEM) to compute the hemodynamics and the elastomechanics within the aortic model, respectively. Physiological data based on transient pressure and velocity profiles are used to set the necessary boundary conditions. Further, the effects of various boundary conditions and definition of contact interactions on the numerical stability of the blood flow and the vessel wall simulation results are also investigated. The quantification of the hemodynamics and the elastomechanics post endovascular intervention provides a realistic controlling of the state of the stented vessel and of the efficiency of the therapy. Consequently, computational modeling would help in evaluating individual therapies and optimal treatment strategies in the field of minimally invasive endovascular surgery.

Hazer, Dilana; Stoll, Markus; Schmidt, Eduard; Richter, Goetz-M.; Dillmann, Rdiger

2010-03-01

345

Dual frequency method for simultaneous translation and real-time imaging of ultrasound contrast agents within large blood vessels  

PubMed Central

A dual frequency excitation method for simultaneous translation and selective real-time imaging of microbubbles is presented. The method can distinguish signals originating from free flowing and static microbubbles. This method is implemented on a programmable scanner with a broadband linear array. The programmable interface allows for dynamic variations in the acoustic parameters and aperture attributes, enabling application of this method to large blood vessels located at varying depths. The performance of the method was evaluated in vitro (vessel diameter 2 mm) by quantifying the sensitivity of the method to various acoustic, microbubble, and fluid flow parameters. It was observed that the static microbubble response maximized at the approximate resonance frequency of the microbubble population (estimated from a coulter counter measurement), thus signifying the need for dual frequency excitation. The static microbubble signal declined from 25 to 12 dB with increasing centerline flow velocities (2.65-15.9 cm/s); indicating applicable range of flow velocities. The maximum intensity of the static microbubbles signal scaled with variations in the microbubble concentration. The rate of increment of static microbubble signal was independent of microbubble concentration. It was deduced that the rate of increment of the static microbubble signal is primarily a function of the pulse frequency, whereas the maximum static microbubble signal intensity is dependent on three parameters: a) the pulse frequency, b) the flow velocity, and c) the microbubble concentration. The proposed dual frequency sequence may enable application of radiation force for optimizing the effect of targeted imaging and modulating drug delivery in large blood vessels with high flow velocities. PMID:19828229

Patil, Abhay V.; Rychak, Joshua J.; Allen, John S.; Klibanov, Alexander L.; Hossack, John A.

2009-01-01

346

Synthetic reconstruction of dynamic blood flow in cortical arteries using optical coherence tomography for the evaluation of vessel compliance  

NASA Astrophysics Data System (ADS)

Optical Coherence Tomography (OCT) has recently been used to produce 3D angiography of microvasculature in the rodent brain in-vivo and blood flow maps of large vessels. Key enabling developments were novel algorithms for detecting Doppler shifts produced by moving scatterers and new scanning protocols tailored to increase sensitivity to small flow speeds. These progresses were pushed by the need for a non invasive imaging modality to monitor quantitative blood flow at a higher resolution and a greater depth than could be achieved by other means. The rationale for this work originates from new hypotheses regarding the role of blood regulation in neurodegenerative diseases and from current investigations of animal models of vascular degeneration. In this work we demonstrate the synthetic reconstruction of dynamic blood flow in mice over the course of a single cardiac cycle in an 800?m wide by ~ 3mm deep B-Frame slice with a lateral resolution of 10?m and a depth resolution of 7?m. Images were taken using a cranial window over the exposed parietal bone of mice skull. Electrocardiography (ECG) recordings were co registered with the OCT A lines at high temporal resolution. QRS peak detection was then used to locate the time value of each A-line in the cardiac cycle and to reconstruct a synthetic temporal frame over one cardiac cycle. Doppler speed in this cardiac cycle was used to measure temporal variations of flow inside arteries and of their area. Three dimensional volume scans yielded measurements of quantitative blood flow on the same arteries. Using these informations a measure of compliance could be established. Comparing measures between atherosclerotic (ATX) and wild type (WT) mice revealed higher blood flow in WT mice, suggested lower systemic compliance in the ATX group but higher compliance of cerebral vasculature on these mice. These results are consistent with expectations showing that OCT is a potential tool for in-vivo arterial compliance evaluation.

Baraghis, Edward; Bolduc, Virginie; Gillis, Marc-Antoine; Srinivasan, Vivek J.; Thorin, ric; Boudoux, Caroline; Lesage, Frdric

2011-03-01

347

C-reactive protein and chitinase 3-like protein 1 as biomarkers of spatial redistribution of retinal blood vessels on digital retinal photography in patients with diabetic retinopathy  

PubMed Central

The aim of the study was to investigate the correlation between the levels of C-reactive protein (CRP) and chitinase 3-like protein 1 (YKL-40) in blood samples with morpohometric parameters of retinal blood vessels in patients with diabetic retinopathy. Blood laboratory examination of 90 patients included the measurement of glycemia, HbA1C, total cholesterol, LDL-C, HDL-C, triglycerides and CRP. Levels of YKL-40 were detected and measured in serum by ELISA (Micro VueYKL-40 EIA Kit, Quidel Corporation, San Diego, USA). YKL-40 correlated positively with diameter and negatively with number of retinal blood vessels. The average number of the blood vessels per retinal zone was significantly higher in the group of patients with mild non-proliferative diabetic retinopathy than in the group with severe form in the optic disc and all five retinal zones. The average outer diameter of the evaluated retinal zones and optic disc vessels was significantly higher in the group with severe compared to the group with mild diabetic retinopathy. Morphological analysis of the retinal vessels on digital fundus photography and correlation with YKL-40 may be valuable for the follow-up of diabetic retinopathy. PMID:25172979

Ceki?, Sonja; Cvetkovi?, Tatjana; Jovanovi?, Ivan; Jovanovi?, Predrag; Pei?, Milica; Babi?, Gordana Stankovi?; Milenkovi?, Svetislav; Risimi?, Dijana

2014-01-01

348

NCI-CCR Pediatric Oncology Branch: Blood and Marrow Transplant - Staff  

Cancer.gov

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349

PIV and digital holography for measuring blood flows and vessel wall dynamics  

NASA Astrophysics Data System (ADS)

In this work endoscopy has been combined with high speed PIV and holographic interferometry for flow velocity and wall deformation measurement of different vessels. Endoscopes have been used for illumination and/or recording of PIV images and digital holograms. High speed PIV has been applied to evaluate the influence of an antithrombotic filter in a vena cava model flow. Qualitative wall deformation has been obtained using digital holography in a vein model and in a real sheep aorta.

Arvalo, Laura; Roche, Eva; Palero, Virginia; Martnez, Miguel ngel; Arroyo, M. Pilar

2013-11-01

350

Abnormal blood vessel development and lethality in embryos lacking a single VEGF allele  

Microsoft Academic Search

THE endothelial cell-specific vascular endothelial growth factor (VEGF)1-5 and its cellular receptors Flt-1 (refs 6,7) and Flk-1 (refs 8,9) have been implicated in the formation of the embryonic vasculature. This is suggested by their colocalized expression during embryogenesis10,11 and the impaired vessel formation in Flk-1 (ref. 12) and Flt-1 (ref. 13) deficient embryos. However, because Flt-1 also binds placental growth

Peter Carmeliet; Valrie Ferreira; Georg Breier; Saskia Pollefeyt; Lena Kieckens; Marina Gertsenstein; Michaela Fahrig; Ann Vandenhoeck; Kendraprasad Harpal; Carmen Eberhardt; Cathrine Declercq; Judy Pawling; Lieve Moons; Dsir Collen; Werner Risau; Andras Nagy

1996-01-01

351

Effect of gravitation stress and hypokinesia on blood vessels of the testicle  

NASA Technical Reports Server (NTRS)

Rabbits were exposed to single maximum endurable stresses of cranio-caudal direction, hypokinesia for periods of one to eight weeks, and hypokinesia followed by gravitation stresses. The stresses caused dilatation of vessels, greater sinuosity, and occasional ruptures of the walls and extravasation. The greater part of the capillaries were dilated; the greatest part constricted. In hypokinesia there was an increasing atrophy of the testes. Significant results are reported.

Palazhchenko, E. F.

1979-01-01

352

PEG Branched Polymer for Functionalization of Nanomaterials with Ultralong Blood Circulation  

Microsoft Academic Search

Nanomaterials have been actively pursued for biological and medical applications in recent years. Here, we report the synthesis of several new poly(ethylene glycol) grafted branched-polymers for functionalization of various nanomaterials including carbon nanotubes, gold nanoparticles (NP) and gold nanorods (NRs), affording high aqueous solubility and stability for these materials. We synthesize different surfactant polymers based upon poly-(g-glutamic acid) (gPGA) and

Giuseppe Prencipe; Scott M. Tabakman; Kevin Welsher; Zhuang Liu; Andrew P. Goodwin; Li Zhang; Joy Henry; Hongjie Dai

2009-01-01

353

Automated detection of kinks from blood vessels for optic cup segmentation in retinal images  

NASA Astrophysics Data System (ADS)

The accurate localization of the optic cup in retinal images is important to assess the cup to disc ratio (CDR) for glaucoma screening and management. Glaucoma is physiologically assessed by the increased excavation of the optic cup within the optic nerve head, also known as the optic disc. The CDR is thus an important indicator of risk and severity of glaucoma. In this paper, we propose a method of determining the cup boundary using non-stereographic retinal images by the automatic detection of a morphological feature within the optic disc known as kinks. Kinks are defined as the bendings of small vessels as they traverse from the disc to the cup, providing physiological validation for the cup boundary. To detect kinks, localized patches are first generated from a preliminary cup boundary obtained via level set. Features obtained using edge detection and wavelet transform are combined using a statistical approach rule to identify likely vessel edges. The kinks are then obtained automatically by analyzing the detected vessel edges for angular changes, and these kinks are subsequently used to obtain the cup boundary. A set of retinal images from the Singapore Eye Research Institute was obtained to assess the performance of the method, with each image being clinically graded for the CDR. From experiments, when kinks were used, the error on the CDR was reduced to less than 0.1 CDR units relative to the clinical CDR, which is within the intra-observer variability of 0.2 CDR units.

Wong, D. W. K.; Liu, J.; Lim, J. H.; Li, H.; Wong, T. Y.

2009-02-01

354

Effect of gravitational overloads, hypokinesia and hypodynamia on the vessels of the pulmonary blood circuit  

NASA Technical Reports Server (NTRS)

Vessels of the pulmonary circuit are studied under normal conditions, in exposure to single stress or continuous threshold endurable chestspine gravitational stresses, and one to eight weak hypokinesia and hypodynamic effects followed by stress. Examination methods include rentgenography and microrentgenography, clearing, and histology. In exposure to gravitational stress the distal portions of the arterial vessels of the 3 and 4 orders constrict, while all veins dilate. Sinuosity of all vessels is noted. The volume of the capillary bed increases and signs of perivascular edema occur. Due to hypokinesia and hypodynamia the arteries constricted and the arterial bed becomes poor. The veins of all orders dilate and the volume of the capillary bed increases. The changes grew greater the longer the terms of hypodyamic effects. Successive combination of hypokinesia and hypodynamia and gravitational stresses cause more pronounced changes than separate effects of these two factors and result in great deformity of the vascular walls, including their rupture and penetration of formed elements beyond the limits of the vascular bed.

Kasimtsev, A. A.

1980-01-01

355

Finite element analysis of nonlinear pulsatile suspension flow dynamics in blood vessels with aneurysm.  

PubMed

A nonlinear pulsatile suspension flow in a dilated vessel is numerically analysed. Two sets of highly coupled nonlinear partial differential equations governing the suspension flow are numerically solved, to simulate the suspension flow dynamics. A transient velocity-pressure (UVP) finite element method (FEM) and a stable time integration scheme, based on a predictor-corrector strategy, with constant error monitoring are employed in the flow analysis. The pulsatile suspension flow is characterized by analysing the flow, pressure and stress fields. Effects of the nonlinear particulate phase on the nonlinear suspending fluid phase are brought out by comparing the suspension flow results with those of homogeneous flow. Particles are seen to dampen the flow velocity, wall and central axis pressure, pressure gradient and wall shear stress. time-dependent recirculation regions which are sensitive to the presence of particles are seen in the dilated portion of the vessel. These recirculation regions favour thrombogenesis. The nonlinear effects due to the vessel geometry and those due to the convective terms dominate the dampening effect of the particles. These nonlinear effects are depicted through the transverse velocity and pressure plots. Wall shear stresses of suspension flow are not only high but also alternate in direction. PMID:7600757

Kumar, B V; Naidu, K B

1995-01-01

356

Endothelial Cell Hyperproliferation and Stratification in Uteroplacental Blood Vessels of the Black Mastiff Bat, Molossus rufus  

PubMed Central

Placentation was studied histologically and immunocytochemically in black mastiff bats obtained at frequent intervals throughout pregnancy. These were bred in a captive colony or collected from a reproductively-synchronized wild population. During late pregnancy, the single fetus was largely sustained by a discoidal, hemochorial placenta located at the cranial end of the right uterine horn. This invariant positioning was determined by a vascular tuft that developed there both during early pregnancy and non-pregnant cycles. This provided a scaffold for early placental morphogenesis. As development proceeded, small arterioles and venules serving the tuft were converted to large uteroplacental vessels. Within the base of the placenta, these became lined by an unusual vascular epithelium composed of intermingled patches of multilayered endothelial cells and cytotrophoblast. Initially, the endothelium became multilayered by hypertrophy, proliferation, and infolding of its basal lamina. These created endothelial bilayers usually insinuated between basal laminae. The development of temporary gaps in the laminae then permitted further enlargement of the vessels and proliferation of the endothelial cells as monolayer sheets or chains. The latter were interconnected, forming a complex, stratified, cellular network associated with a prominent meshwork of basal laminae. Throughout much of pregnancy, these endothelial cells were cuboidal to columnar and possessed an abundance of basal glycoprotein granules presumably containing basal lamina precursors. The cells also expressed vimentin and frequently von Willebrand factor, but not cytokeratins or desmin. Pronounced thickening of the endothelia and amplification of their basal laminae likely evolved to greatly strengthen the walls of the uteroplacental vessels. PMID:21764447

Rasweiler IV, J.J.; Badwaik, N.K.; Salame, G.; Abulafia, O.

2011-01-01

357

Small vessel hematocrit in ischemic myocardium  

SciTech Connect

As blood enters the microvasculature of normally perfused myocardium, there is a progressive decrease in small vessel hematocrit (SV Hct) due to RBC streaming in smaller branching vessels and the Fahraeus-Lindqvist effect. We hypothesized that if the coronary collateral circulation was composed of very small vessels branching from large parent vessels, plasma streaming would result in a further decrease of SV Hct in ischemic myocardium. Six open chest anesthetized dogs were studied. Plasma was labelled with /sup 59/FeCl siderophilin and RBC's with /sup 99/mTc to estimate SV Hct from myocardial biopsies. The LAD was occluded and cannulated for measurement of retrograde flow (arising presumably from proximal collaterals). The ischemic region was identified using the microsphere shadow technique. Collateral flow after LAD occlusion was 30 +- 12 ml/min 100g (x +- SE). Systemic Hct was 40 +- 1%. The Hct of blood from retrograde flow was 39 +- 1% (p = NS). Activity of /sup 59/FeCl and /sup 99/mTc in known quantities of blood were compared to myocardial biopsies to estimate SV Hct. Ischemic SV Hct was 23 +- 2% and non-ischemic SV Hct was 21 +- 1% (p = NS). We conclude that the size and branching pattern of coronary collaterals is such that plasma streaming in collaterals does not result in an additional decrease in SV Hct in ischemic myocardium.

Gumm, D.C.; Cooper, S.M.; Marcus, M.L.; Chilian, W.M.; Harrison, D.G.

1986-03-01

358

Similarity of vasorelaxant effects of natriuretic peptides in isolated blood vessels of salmonids.  

PubMed

Natriuretic peptides (NPs) have been implicated in cardiovascular regulation in rainbow trout (Oncorhyncus mykiss), and it has been observed that the vasorelaxant activity of distinct trout and human NPs is similar in isolated trout arteries. This study characterizes the response of a variety of vessels from rainbow trout and other salmonids to different NPs. The effects of heterologous (rat atrial and human atrial) and homologous (rainbow trout atrial and rainbow trout ventricular) NPs were examined in precontracted efferent branchial arteries from rainbow trout (O. mykiss, Kamloops strain), lake whitefish (Coregonus clupeaformis), and in rainbow trout celiacomesenteric arteries and anterior cardinal veins. The response to mammalian NPs was also examined in efferent branchial arteries from the steelhead (O. mykiss, Skamania strain), coho salmon (Oncorhyncus kisutch), brook trout (Salvelinus fontinalis), and brown trout (Salmo trutta). In general, there were relatively few differences that were species, peptide, or vessel specific. There was no difference in the sensitivity (concentration producing a half-maximal response EC(50)) or efficacy (percent relaxation, i.e., E(max)) of trout or whitefish efferent branchial arteries to any NP, except human NP, which was significantly less effective (greater EC(50) and lower E(max)) in whitefish arteries. There were no differences in E(max) of mammalian NPs in efferent branchial arteries from any species, and only coho and brook trout had significantly different EC(50)'s (coho, 1.0+/-0.2 nM; brook trout, 4. 2+/-0.6 nM; and other species, from 1.9 to 3.5 nM). Rainbow and coho anterior cardinal veins were less sensitive than arteries to mammalian NPs (EC(50)'s; 8.8+/-2.0, 2.0+/-0.1 vs. 3.0+/-0.9, 1.0+/-0. 2, respectively), whereas brown trout veins were more sensitive (1. 0+/-0.2, 3.5+/-1.3, respectively). Sodium nitroprusside (SNP), which activates soluble guanylate cyclase, was vasodilatory, albeit significantly less potent than all NPs, in efferent branchial arteries of all species. SNP was significantly more potent in trout than whitefish efferent branchial arteries, whereas it was equally efficacious in these vessels. These results demonstrate that multiple vessels from various salmonids are similarly responsive to the vasorelaxant effects of a variety of NPs and that the salmonid NP receptor has relatively little ability to discriminate between homologous and heterologous peptides. We conclude that the vascular NP receptor complex is highly conserved among salmonids. Further, salmonids utilize cyclic guanosine monophosphate (cGMP) elevations for reductions of vascular tonus by both particulate and soluble guanylate cyclase pathways. PMID:11009403

Smith, M P; Takei, Y; Olson, K R

2000-01-01

359

Detergent-Enzymatic Decellularization of Swine Blood Vessels: Insight on Mechanical Properties for Vascular Tissue Engineering  

PubMed Central

Small caliber vessels substitutes still remain an unmet clinical need; few autologous substitutes are available, while synthetic grafts show insufficient patency in the long term. Decellularization is the complete removal of all cellular and nuclear matters from a tissue while leaving a preserved extracellular matrix representing a promising tool for the generation of acellular scaffolds for tissue engineering, already used for various tissues with positive outcomes. The aim of this work is to investigate the effect of a detergent-enzymatic decellularization protocol on swine arteries in terms of cell removal, extracellular matrix preservation, and mechanical properties. Furthermore, the effect of storage at ?80C on the mechanical properties of the tissue is evaluated. Swine arteries were harvested, frozen, and decellularized; histological analysis revealed complete cell removal and preserved extracellular matrix. Furthermore, the residual DNA content in decellularized tissues was far low compared to native one. Mechanical testings were performed on native, defrozen, and decellularized tissues; no statistically significant differences were reported for Young's modulus, ultimate stress, compliance, burst pressure, and suture retention strength, while ultimate strain and stress relaxation of decellularized vessels were significantly different from the native ones. Considering the overall results, the process was confirmed to be suitable for the generation of acellular scaffolds for vascular tissue engineering. PMID:23865072

Pellegata, Alessandro F.; Asnaghi, M. Adelaide; Stefani, Ilaria; Maestroni, Anna; Maestroni, Silvia; Dominioni, Tommaso; Zonta, Sandro; Zerbini, Gianpaolo; Mantero, Sara

2013-01-01

360

Study in Nature: MicroRNAs Hold Promise For Treating Diseases in Blood Vessels  

E-print Network

atherosclerosis and Alzheimer's disease, according to an article published online today in the journal Nature and Dentistry. Thanks to stem cells, humans develop from a single cell embryo into a complex being with about (bone, nerve, blood, skin, muscle, etc.). To serve specific roles in the body, some stem cells also

Goldman, Steven A.

361

Patterns of blood flow in episcleral vessels studied by low-dose fluorescein videoangiography  

Microsoft Academic Search

The blood supply of the ocular anterior segment arises from a saggittal arterial ring composed of the long posterior ciliary arteries, the muscular and anterior ciliary arteries and perforating scleral arteries. This ring supplies coronal arterial circles within and outside the globe.Low dose anterior segment fluorescein videoangiography demonstrates arterial and venous flow, recording its characteristics and direction.Videoangiograms were performed at

Paul A R Meyer

1988-01-01

362

3D MRI-based Predictive Control of a Ferromagnetic Microrobot Navigating in Blood Vessels  

E-print Network

, especially in the blood circulatory system, a very large number of remote locations in the human body become the human cardiovascular system. A system software architecture is presented illustrating the different in the cardiovascular system are a prolific research area for minimally invasive surgeries [1][2] and treatments

Paris-Sud XI, Université de

363

Human vasculogenic cells form functional blood vessels and mitigate adverse remodeling after ischemia reperfusion injury in rats  

PubMed Central

Cell-based therapies to restore heart function after infarction have been tested in pre-clinical models and clinical trials with mixed results, and will likely require both contractile cells and a vascular network to support them. We and others have shown that human endothelial colony forming cells (ECFC) combined with mesenchymal progenitor cells (MPC) can be used to bio-engineer functional human blood vessels. Here we investigated whether ECFC + MPC form functional vessels in ischemic myocardium and whether this affects cardiac function or remodeling. Myocardial ischemia/reperfusion injury (IRI) was induced in 12-week-old immunodeficient rats by ligation of the left anterior descending coronary artery. After 40 min, myocardium was reperfused and ECFC + MPC (2 106 cells, 2:3 ratio) or PBS was injected. Luciferase assays after injection of luciferase-labeled ECFC + MPC showed that 1,500 ECFC were present at day 14. Human ECFC-lined perfused vessels were directly visualized by femoral vein injection of a fluorescently-tagged human-specific lectin in hearts injected with ECFC + MPC but not PBS alone. While infarct size at day 1 was no different, LV dimensions and heart weight to tibia length ratios were lower in cell-treated hearts compared with PBS at 4 months, suggesting post-infarction remodeling was ameliorated by local cell injection. Fractional shortening, LV wall motion score, and fibrotic area were not different between groups at 4 months. However, pressurevolume loops demonstrated improved cardiac function and reduced volumes in cell-treated animals. These data suggest that myocardial delivery of ECFC + MPC at reperfusion may provide a therapeutic strategy to mitigate LV remodeling and cardiac dysfunction after IRI. PMID:23666122

Kang, Kyu-Tae; Coggins, Matthew; Xiao, Chunyang; Rosenzweig, Anthony

2013-01-01

364

A Phenomenological Model for Mechanically Mediated Growth, Remodeling, Damage, and Plasticity of Gel-Derived Tissue Engineered Blood Vessels  

PubMed Central

Mechanical stimulation has been shown to dramatically improve mechanical and functional properties of gel-derived tissue engineered blood vessels (TEBVs). Adjusting factors such as cell source, type of extracellular matrix, cross-linking, magnitude, frequency, and time course of mechanical stimuli (among many other factors) make interpretation of experimental results challenging. Interpretation of data from such multifactor experiments requires modeling. We present a modeling framework and simulations for mechanically mediated growth, remodeling, plasticity, and damage of gel-derived TEBVs that merge ideas from classical plasticity, volumetric growth, and continuum damage mechanics. Our results are compared with published data and suggest that this model framework can predict the evolution of geometry and material behavior under common experimental loading scenarios. PMID:19831486

Raykin, Julia; Rachev, Alexander I.

2011-01-01

365

[The examination of the blood flow velocity in arterial vessel during and after encephalo-dura-arterio-synangiosis. Preliminary results].  

PubMed

The Japanese authors first described encephalo-duro-arterio-synangiosis, a new treatment for moya-moya disease, 17 years ago. The other authors used this method (EDAS, indirect anastomosis) in surgical treatment of patients suffered cerebral transient ischaemic attack and cerebral ischaemia. In our department this method was applied in 5 patients with cerebral ischaemia. All patients had internal carotid artery occlusion. After angiography, to localize carotid artery occlusion, acetazolamid (Diamox) test was performed. The patients with negative Diamox test were treated surgically (EDAS). The authors used the intraoperative microdoppler device to monitor blood flow velocity of the prepared vessel (temporal superficial artery) at every stage of surgery. The device was also useful in controlling the patency of encephalo-duro-arterio-synangiosis percutaneously after the surgery. The proximal and the distal part of the non-bypass anastomosis was examined in the follow up during 5-8 months before angiography. PMID:10463233

Andrychowski, J; Czernicki, Z; Bogucki, J; Nauman, P; Piwowarski, G

1998-01-01

366

Mechanical properties of completely autologous human tissue engineered blood vessels compared to human saphenous vein and mammary artery  

PubMed Central

We have previously reported initial clinical feasibility with our small diameter tissue engineered blood vessel (TEBV). Here we present in vitro results of the mechanical properties of the TEBVs of the first 25 patients enrolled in an arterio-venous (A-V) shunt safety trial, and compare these properties with those of risk-matched human vein and artery. TEBV average burst pressures (3,490 +/? 892 mmHg, n=230) were higher than native saphenous vein (SV) (1,599 +/? 877 mmHg, n=7), and not significantly different than native internal mammary artery (IMA) (3,196 +/? 1,264 mmHg, n=16). Suture retention strength for the TEBVs (152 +/? 50 gmf) was also not significantly different than IMA (138 +/? 50 gmf). Compliance for the TEBVs prior to implantation (3.4 +/? 1.6 %/100 mmHg) was lower than IMA (11.5 +/? 3.9 %/100 mmHg). By 6 months post-implant, the TEBV compliance (8.8 +/? 4.2 %/100 mmHg, n=5) had increased to values comparable to IMA, and showed no evidence of dilation or aneurysm formation. With clinical time points beyond 21 months as an A-V shunt without intervention, the mechanical tests and subsequent lot release criteria reported here would seem appropriate minimum standards for clinical use of tissue engineered vessels. PMID:19111338

Konig, Gerhardt; McAllister, Todd N; Dusserre, Nathalie; Garrido, Sergio A; Iyican, Corey; Marini, Alicia; Fiorillo, Alex; Avila, Hernan; Wystrychowski, Wojciech; Zagalski, Krzysztof; Maruszewski, Marcin; Jones, Alyce Linthurst; Cierpka, Lech; de la Fuente, Luis M; LHeureux, Nicolas

2009-01-01

367

Endothelial Wnt/?-catenin signaling inhibits glioma angiogenesis and normalizes tumor blood vessels by inducing PDGF-B expression  

PubMed Central

Endothelial Wnt/?-catenin signaling is necessary for angiogenesis of the central nervous system and bloodbrain barrier (BBB) differentiation, but its relevance for glioma vascularization is unknown. In this study, we show that doxycycline-dependent Wnt1 expression in subcutaneous and intracranial mouse glioma models induced endothelial Wnt/?-catenin signaling and led to diminished tumor growth, reduced vascular density, and normalized vessels with increased mural cell attachment. These findings were corroborated in GL261 glioma cells intracranially transplanted in mice expressing dominant-active ?-catenin specifically in the endothelium. Enforced endothelial ?-catenin signaling restored BBB characteristics, whereas inhibition by Dkk1 (Dickkopf-1) had opposing effects. By overactivating the Wnt pathway, we induced the Wnt/?-cateninDll4/Notch signaling cascade in tumor endothelia, blocking an angiogenic and favoring a quiescent vascular phenotype, indicated by induction of stalk cell genes. We show that ?-catenin transcriptional activity directly regulated endothelial expression of platelet-derived growth factor B (PDGF-B), leading to mural cell recruitment thereby contributing to vascular quiescence and barrier function. We propose that reinforced Wnt/?-catenin signaling leads to inhibition of angiogenesis with normalized and less permeable vessels, which might prove to be a valuable therapeutic target for antiangiogenic and edema glioma therapy. PMID:22908324

Reis, Marco; Czupalla, Cathrin J.; Ziegler, Nicole; Devraj, Kavi; Zinke, Jenny; Seidel, Sascha; Heck, Rosario; Thom, Sonja; Macas, Jadranka; Bockamp, Ernesto; Fruttiger, Marcus; Taketo, Makoto M.; Dimmeler, Stefanie; Plate, Karl H.

2012-01-01

368

Apolipoprotein E4 and beta amyloid in senile plaques and cerebral blood vessels of aged rhesus monkeys.  

PubMed Central

Recent studies of late onset familial and sporadic Alzheimer's disease (AD) show a genetic disequilibrium between inheritance of the epsilon 4 allele of the apolipoprotein E (ApoE) gene and development of AD. beta-Amyloid (A beta)-positive senile plaques and blood vessels in AD are immunoreactive for ApoE, suggesting that ApoE plays a role in amyloid deposition. We examined the brains of nine rhesus monkeys (Macaca mulatta) to determine the immunohistochemical distribution of ApoE and to investigate the association of ApoE with A beta in this species. Antibodies to ApoE and A beta labeled senile plaques and vessels in the brains of aged monkeys, indicating cross-species homogeneity of the association of these two proteins. Polymerase chain reaction/restriction enzyme analysis of the ApoE epsilon 3/epsilon 4 allelic site (residue 112) in the rhesus monkey revealed that the rhesus has an arginine at this site like the human epsilon 4 allele, the cynomolgus monkey, baboon, cow, pig, mouse, and rat but unlike the human epsilon 3 allele and the rabbit. These results emphasize the value of aged nonhuman primates as animal models for A beta deposition and ApoE4-A beta interactions in AD and aging. Images Figure 1 Figure 2 PMID:8203459

Poduri, A.; Gearing, M.; Rebeck, G. W.; Mirra, S. S.; Tigges, J.; Hyman, B. T.

1994-01-01

369

New findings on the three-dimensional anatomical relations between the bronchi and pulmonary blood vessels at the pulmonary hilum.  

PubMed

During the 1940s, considerable knowledge was acquired about the anatomy of pulmonary segments, and anatomical terms were proposed and have been widely accepted. In recent years, minimally invasive and thoracoscopic segmentectomy has been performed with a versatile sublobar resection approach on patients with early peripheral lung cancer, metastatic lung tumors, and undiagnosed nodules. The three-dimensional (3D) anatomy of the bronchi and the pulmonary vessels has also been studied in individual patients. Three-dimensional models of the bronchi and pulmonary vessels were prepared using homemade software from computed tomograms (CT) of the chests of patients scheduled to undergo surgical procedures. Using these models, the authors examined the 3D positional relationships of the segmental broncho-arterial triangle (SBAT) created by three points defined by the origins and courses of the bronchi and the pulmonary arteries, which are located apart from each other at the pulmonary hilum, and the segmental pulmonary veins (SPV), which run near the SBAT. In the left and right upper lobes, many branches of the pulmonary arteries and parallel bronchi in subsegments were widely separated at the origin of the pulmonary hilum, creating a relatively large SBAT. However, as an exceptional case, an SPV passed through an SBAT in only one of 158 patients. To our knowledge, no similar findings have been documented previously. Our findings could help to determine resection surfaces for thoracoscopic segmentectomy in the future, and provide new insights into the 3D anatomy and development of the lung. Clin. Anat. 28:506-511, 2015. 2014 Wiley Periodicals, Inc. PMID:25546314

Onuki, Takamasa; Kanzaki, Masato; Kikkawa, Takuma; Isaka, Tamami; Sakamoto, Kei; Oyama, Kunihiro; Murasugi, Masahide

2015-05-01

370

Correlation of carotid artery disease severity and vasomotor response of cerebral blood vessels.  

PubMed

We assessed reactivity of cerebral vessels on hypercapnia in patients with carotid occlusive disease. The effects of vascular risk factors on carotid atherosclerosis and vasomotor reactivity (VMR) of cerebral arterioles were also examined. Patients (n = 50) with carotid stenosis (?30% in 1 or both sides) were included; 30 patients acted as controls. Hypertension, hyperlipidemia, diabetes, cardiac diseases, inflammation, and smoking were recorded. Vasomotor reactivity was assessed with the apnea test by transcranial Doppler ultrasonography and estimated by flow velocity changes in the middle cerebral artery before and after hypercapnia induction. Vasomotor reactivity was defined by the breath holding index, and values under 0.69 were considered critical for VMR impairment. Vasomotor reactivity reduction was significant (P = .004) in patients with severe carotid stenosis (>70%) and with symptomatic carotid disease (P < .05). The risk factors did not significantly influence VMR reduction. Severe carotid stenosis impairs VMR and may increase the risk of stroke, especially in symptomatic patients. PMID:24904181

Krdi?, Ivana; ?ovi?kovi?-terni?, Nadeda; Katsiki, Niki; Isenovi?, Esma R; Radak, ?or?e

2015-05-01

371

Iodine imaging using spectral analysis. [radiography for visualization of small blood vessels  

NASA Technical Reports Server (NTRS)

Existing radiographic imaging systems provide images which represent an integration or averaging over the energy spectrum. In order to provide noninvasive angiography it is necessary to image the relatively small amounts of iodine which are available following an intravenous administration. This is accomplished by making use of the special spectral characteristics of iodine. Two methods will be presented. One involves a special grating for encoding the iodine information in the form of a fine line pattern. This is subsequently decoded to provide images of iodinated structures which are otherwise almost invisible. The second method utilizes a scanned X-ray beam which is rapidly switched in the high energy region. In this region, iodine experiences significant variations in the attenuation coefficient while bone and soft tissue do not. An efficient and accurate X-ray detector can be used with scanned X-ray beams. This provides a high degree of sensitivity enabling the visualization of small vessels containing relatively dilute iodine.

Macovski, A.

1978-01-01

372

Simultaneous invivo imaging of blood and lymphatic vessel growth in Prox1-GFP/Flk1::myr-mCherry mice.  

PubMed

The ability to visually observe angiogenesis and lymphangiogenesis simultaneously and repeatedly in living animals would greatly enhance our understanding of the inter-dependence of these processes. To generate a mouse model that allows such visualization via invivo fluorescence imaging, we crossed Prox1-GFP mice with Flk1::myr-mCherry mice to generate Prox1-GFP/Flk1::myr-mCherry mice, in which lymphatic vessels emit green fluorescence and blood vessels emit red fluorescence. Corneal neovascularization was induced in these mice using three injury models: implantation of a vascular endothelial growth factor (VEGF) pellet, implantation of a basic fibroblast growth factor (bFGF) pellet, and alkali burn injury. Vessel growth was observed invivo by stereomicroscopy on days 0, 3, 7 and 10 after pellet implantation or alkali injury as well as in flat-mounted corneas via confocal microscopy after the final invivo imaging time point. We observed blood and lymphatic vessel growth in all three models, with the most significant growth occurring from days 0-7. Upon VEGF stimulation, the growth kinetics of blood and lymphatic vessels were similar. Blood vessels exhibited similar growth patterns in VEGF- and bFGF-stimulated corneas. Alkali burn injury induced robust angiogenesis and lymphangiogenesis. The intrinsic fluorescence of blood and lymphatic endothelial cells in Prox1-GFP/Flk1::myr-mCherry mice permitted simultaneous invivo imaging of angiogenesis and lymphangiogenesis. This allowed us to differentiate the processes as well as observe their inter-dependence, and will be valuable in development of therapies targeting angiogenesis and/or lymphangiogenesis. PMID:25688651

Zhu, Jimmy; Dugas-Ford, Jennifer; Chang, Michael; Purta, Patryk; Han, Kyu-Yeon; Hong, Young-Kwon; Dickinson, Mary E; Rosenblatt, Mark I; Chang, Jin-Hong; Azar, Dimitri T

2015-04-01

373

Vessel Segmentation and Blood Flow Simulation Using Level-Sets and Embedded Boundary Methods  

SciTech Connect

In this article we address the problem of blood flow simulation in realistic vascular objects. The anatomical surfaces are extracted by means of Level-Sets methods that accurately model the complex and varying surfaces of pathological objects such as aneurysms and stenoses. The surfaces obtained are defined at the sub-pixel level where they intersect the Cartesian grid of the image domain. It is therefore straightforward to construct embedded boundary representations of these objects on the same grid, for which recent work has enabled discretization of the Navier-Stokes equations for incompressible fluids. While most classical techniques require construction of a structured mesh that approximates the surface in order to extrapolate a 3D finite-element gridding of the whole volume, our method directly simulates the blood-flow inside the extracted surface without losing any complicated details and without building additional grids.

Deschamps, T; Schwartz, P; Trebotich, D; Colella, P; Saloner, D; Malladi, R

2004-12-09

374

Optical monitoring of complex dynamics of blood sedimentation and lymph flow in vessels  

NASA Astrophysics Data System (ADS)

In this paper a few examples of the complex behavior of biological systems detected by optical techniques are described. All examples are related to cell suspensions behavior in in vitro and in vivo studies. In vitro studies performing investigation of a fine structure of blood sedimentation process and establishing nonlinear features of blood sedimentation as disease prognostic parameters are overviewed. Three optical techniques: OCT, CW laser beam transverse synchronized transillumination method and spatially-modulated laser beam transillumination method were considered. In blood sedimentation studied by OCT the regular or irregular oscillations of the RBC/plasma boundary were observed. The functional properties of erythrocytes in patients with coronary heart disease by mean of spatially-modulated laser beam transillumination method to reveal the stages of the acute coronary syndrome formation are discussed. The laser speckle and intravital TV-microscopic techniques applied to in vivo studies of lymph flow in microvessels are overviewed. The hypothesis on the alternating-translation (shuttle-stream) character of lymph flow is discussed.

Tuchin, Valery V.

2004-05-01

375

Blood flow and arterial vessel diameter change during graded handgrip exercise in dominant and non-dominant forearms of tennis players.  

PubMed

The training effect on exercise-induced maximal blood flow remains unclear. The purpose of this study was to clarify the difference of exercise-induced blood flow, blood flow velocity and vessel diameter of brachial artery in dominant and non-dominant forearms of tennis players during graded hand-grip exercise. Ten female tennis players aged 20.1 +/- 0.1 years. (mean +/- SD) performed 30-s static handgrip exercise in the supine position with either the dominant or non-dominant hand by increasing load at 30-s intervals until exhaustion. Brachial arterial blood flow velocity (Doppler ultrasound method) did not differ between both limbs, whereas the vessel diameter (2-D method) was significantly larger in the dominant limb during diastole both at baseline (p < 0.01) and after exercise (p < 0.05), but no difference was found during systole. As a result, the blood flow was significantly higher (p < 0.05) in the dominant limb during post-exercise condition. Muscle thickness of the forearm muscles and maximal handgrip strength were significantly higher in the dominant limb. Thus, the effect of training on exercise-induced blood flow specific to the dominant limb was confirmed during post-exercise due to the enlarged vessel diameter during diastole of cardiac cycle. The dimensional change in the vasculature specific to the dominant side will be included in the training effects associated with the dimensional muscular changes in the dominant forearm. PMID:20204817

Kagaya, Atsuko; Ohmori, Fumiko; Okuyama, Shizuyo; Muraoka, Yoshiho; Sato, Kohei

2010-01-01

376

A cellular nonlinear network: real-time technology for the analysis of microfluidic phenomena in blood vessels  

NASA Astrophysics Data System (ADS)

A new approach to the observation and analysis of dynamic structural and functional parameters in the microcirculation is described. The new non-invasive optical system is based on cellular nonlinear networks (CNNs), highly integrated analogue processor arrays whose processing elements, the cells, interact directly within a finite local neighbourhood. CNNs, thanks to their parallel processing feature and spatially distributed structure, are widely used to solve high-speed image processing and recognition problems and in the description and modelling of biological dynamics through the solution of time continuous partial differential equations (PDEs). They are therefore considered extremely suitable for spatial-temporal dynamic characterization of fluidic phenomena at micrometric to nanometric scales, such as blood flow in microvessels and its interaction with the cells of the vessel wall. A CNN universal machine (CNN-UM) structure was used to implement, via simulation and hardware (ACE16k), the algorithms to determine the functional capillarity density (FCD) and red blood cell velocity (RBCV) in capillaries obtained by intravital microscopy during in vivo experiments on hamsters. The system exploits the moving particles to distinguish the functional capillaries from the stationary background. This information is used to reconstruct a map and to calculate the velocity of the moving objects.

Sapuppo, F.; Bucolo, M.; Intaglietta, M.; Fortuna, L.; Arena, P.

2006-02-01

377

Blood Thinners  

MedlinePLUS

If you have some kinds of heart or blood vessel disease, or if you have poor blood flow to your brain, your doctor may recommend that you take a blood thinner. Blood thinners reduce the risk of heart ...

378

Blood clotting  

MedlinePLUS Videos and Cool Tools

... the external bleeding stops. Clotting factors in the blood cause strands of blood-borne material, called fibrin, to stick together and ... the inside of the wound. Eventually, the cut blood vessel heals, and the blood clot dissolves after ...

379

Mechanotransduction in Vascular Endothelial Cells: Mechanisms and Implications The ability of arterial endothelial cells, the cells lining the inner surfaces of blood vessels, to  

E-print Network

of arterial endothelial cells, the cells lining the inner surfaces of blood vessels, to respond to mechanicalMechanotransduction in Vascular Endothelial Cells: Mechanisms and Implications The ability cell mechanotransduction play a critical role in the development and progression of cardiovascular

Mayberry, Marty

380

Location and size of carotid body-like organs (paraganglia) revealed in rats by the permeability of blood vessels to Evans blue dye  

Microsoft Academic Search

Summary We determined the number, distribution, size, and morphology of paraganglia near the glossopharyngeal, vagus, and sympathetic nerves of rats. The location of paraganglia was revealed by a method that takes advantage of the comparatively high permeability of their blood vessels to Evans blue dye. Rats were fixed by vascular perfusion of glutaraldehyde 2 min after receiving an intravenous injection

Donald M. McDonald; Richard W. Blewett

1981-01-01

381

DNA Methylation is Altered in Maternal Blood Vessels of Women With Preeclampsia  

PubMed Central

We analyzed 27578 CpG sites that map to 14495 genes in omental arteries of normal pregnant and preeclamptic women for DNA methylation status using the Illumina platform. We found 1685 genes with a significant difference in DNA methylation at a false discovery rate of <10% with many inflammatory genes having reduced methylation. Unsupervised hierarchical clustering revealed natural clustering by diagnosis and methylation status. Of the genes with significant methylation differences, 236 were significant at a false discovery rate of <5%. When data were analyzed more stringently to a false discovery rate of <5% and difference in methylation of >0.10, 65 genes were identified, all of which showed reduced methylation in preeclampsia. When these genes were mapped to gene ontology for molecular functions and biological processes, 75 molecular functions and 149 biological processes were overrepresented in the preeclamptic vessels. These included smooth muscle contraction, thrombosis, inflammation, redox homeostasis, sugar metabolism, and amino acid metabolism. We speculate that reduced methylation may contribute to the pathogenesis of preeclampsia and that alterations in DNA methylation resulting from preeclampsia may increase maternal risk of cardiovascular disease later in life. PMID:22902744

Mousa, Ahmad A.; Archer, Kellie J.; Cappello, Renato; Estrada-Gutierrez, Guadalupe; Isaacs, Christine R.; Strauss,, Jerome F.

2012-01-01

382

Frictional properties of light-activated antimicrobial polymers in blood vessels.  

PubMed

The adhesion of microbes to catheter surfaces is a serious problem and the resulting infections frequently lead to longer hospitalisation and higher risk for the patient. Several approaches have been developed to produce materials that are less susceptible to microbial colonisation. One such approach is the incorporation of photoactivated compounds, such as Toluidine Blue O (TBO), in the polymeric matrix resulting in 'light-activated antimicrobial materials'. The insertion and removal of catheters can cause tissue damage and patient discomfort through frictional forces; hence the lubricity of a catheter material is also very important. In this work the tribological performance of silicone and polyurethane containing TBO and gold nanoparticles were evaluated using two different surfaces, the inner part of the aorta and the superior vena cava of sheep. Static and kinetic friction coefficients of these materials were measured using a tribometric device developed for in vitro applications using dry materials and those lubricated with blood. It was found that neither the preparation process nor the presence of TBO or gold nanoparticles, had an effect on the friction factors in comparison to those of untreated materials. In all cases, static and kinetic friction coefficients on aorta tissue were higher than those on vena cava due to higher surface roughness of the aorta. The presence of blood as a lubricant resulted in lower friction coefficients. PMID:19784866

Prokopovich, Polina; Perni, Stefano; Piccirillo, Clara; Pratten, Jonathan; Parkin, Ivan P; Wilson, Michael

2010-02-01

383

A three-dimensional atlas of human dermal leukocytes, lymphatics, and blood vessels.  

PubMed

Dendritic cells (DCs), macrophages (M?), and T cells are major components of the skin immune system, but their interstitial spatial organization is poorly characterized. Using four-channel whole-mount immunofluorescence staining of the human dermis, we demonstrated the three-dimensional distribution of CD31(+) blood capillaries, LYVE-1(+) lymphatics, discrete populations of CD11c(+) myeloid DCs, FXIIIa(+) M?, and lymphocytes. We showed phenotypic and morphological differences in situ between DCs and M?. DCs formed the first dermal cellular layer (0-20 ?m beneath the dermoepidermal junction), M? were located deeper (40-60 ?m), and CD3(+) lymphocytes were observed throughout (0-60 ?m). Below this level, DCs, T cells, and the majority of M? formed stable perivascular sheaths. Whole-mount imaging revealed the true extent of dermal leukocytes previously underestimated from cross-section views. The total area of apical dermis (0-30 ?m) contained approximately 10-fold more myeloid DCs than the entire blood volume of an average individual. Surprisingly, <1% of dermal DCs occupied lymphatics in freshly isolated skin. Dermal DCs rapidly accumulated within lymphatics, but M? remained fixed in skin explants cultured ex vivo. The leukocyte architecture observed in normal skin was distorted in inflammation and disease. These studies illustrate the micro-anatomy of dermal leukocytes and provide further insights into their functional organization. PMID:24352044

Wang, Xiao-Nong; McGovern, Naomi; Gunawan, Merry; Richardson, Connor; Windebank, Martin; Siah, Tee-Wei; Lim, Hwee-Ying; Fink, Katja; Li, Jackson L Yao; Ng, Lai G; Ginhoux, Florent; Angeli, Veronique; Collin, Matthew; Haniffa, Muzlifah

2014-04-01

384

Nampt/PBEF/visfatin serum levels: a new biomarker for retinal blood vessel occlusions  

PubMed Central

The main objective of the study was to quantify serum levels of nicotinamide phosphoribosyltransferase (Nampt/pre-B-Cell colony-enhancing factor 1/visfatin) in subjects with a history of retinal vascular occlusions (RVOs), disease conditions characterized by pronounced ischemia, and metabolic energy deficits. A casecontrol study of 18 subjects with a history of RVO as well as six healthy volunteers is presented. Serum Nampt levels were quantified using a commercially available enzyme-linked immunosorbent assay kit. Serum Nampt levels were 79% lower in patients with a history of RVO compared with that in healthy volunteers (P<0.05). There was no statistically significant difference among the types of RVOs, specifically branch retinal vein occlusions (n=7), central retinal vein occlusions (n=5), hemiretinal vein occlusions (n=3), and central retinal artery occlusions (n=3; P=0.69). Further studies are needed to establish the temporal kinetics of Nampt expression and to determine whether Nampt may represent a novel biomarker to identify at-risk populations, or whether it is a druggable target with the potential to ameliorate the long-term complications associated with the condition, ie, macular edema, macular ischemia, neovascularization, and permanent loss of vision.

Kaja, Simon; Shah, Anna A; Haji, Shamim A; Patel, Krishna B; Naumchuk, Yuliya; Zabaneh, Alexander; Gerdes, Bryan C; Kunjukunju, Nancy; Sabates, Nelson R; Cassell, Michael A; Lord, Ron K; Pikey, Kevin P; Poulose, Abraham; Koulen, Peter

2015-01-01

385

Openings between Defective Endothelial Cells Explain Tumor Vessel Leakiness  

PubMed Central

Leakiness of blood vessels in tumors may contribute to disease progression and is key to certain forms of cancer therapy, but the structural basis of the leakiness is unclear. We sought to determine whether endothelial gaps or transcellular holes, similar to those found in leaky vessels in inflammation, could explain the leakiness of tumor vessels. Blood vessels in MCa-IV mouse mammary carcinomas, which are known to be unusually leaky (functional pore size 1.22 ?m), were compared to vessels in three less leaky tumors and normal mammary glands. Vessels were identified by their binding of intravascularly injected fluorescent cationic liposomes and Lycopersicon esculentum lectin and by CD31 (PECAM) immunoreactivity. The luminal surface of vessels in all four tumors had a defective endothelial monolayer as revealed by scanning electron microscopy. In MCa-IV tumors, 14% of the vessel surface was lined by poorly connected, overlapping cells. The most superficial lining cells, like endothelial cells, had CD31 immunoreactivity and fenestrae with diaphragms, but they had a branched phenotype with cytoplasmic projections as long as 50 ?m. Some branched cells were separated by intercellular openings (mean diameter 1.7 ?m; range, 0.34.7 ?m). Transcellular holes (mean diameter 0.6 ?m) were also present but were only 8% as numerous as intercellular openings. Some CD31-positive cells protruded into the vessel lumen; others sprouted into perivascular tumor tissue. Tumors in RIP-Tag2 mice had, in addition, tumor cell-lined lakes of extravasated erythrocytes. We conclude that some tumor vessels have a defective cellular lining composed of disorganized, loosely connected, branched, overlapping or sprouting endothelial cells. Openings between these cells contribute to tumor vessel leakiness and may permit access of macromolecular therapeutic agents to tumor cells. PMID:10751361

Hashizume, Hiroya; Baluk, Peter; Morikawa, Shunichi; McLean, John W.; Thurston, Gavin; Roberge, Sylvie; Jain, Rakesh K.; McDonald, Donald M.

2000-01-01

386

Arginase reciprocally regulates nitric oxide synthase activity and contributes to endothelial dysfunction in aging blood vessels  

NASA Technical Reports Server (NTRS)

BACKGROUND: Although abnormal L-arginine NO signaling contributes to endothelial dysfunction in the aging cardiovascular system, the biochemical mechanisms remain controversial. L-arginine, the NO synthase (NOS) precursor, is also a substrate for arginase. We tested the hypotheses that arginase reciprocally regulates NOS by modulating L-arginine bioavailability and that arginase is upregulated in aging vasculature, contributing to depressed endothelial function. METHODS AND RESULTS: Inhibition of arginase with (S)-(2-boronoethyl)-L-cysteine, HCl (BEC) produced vasodilation in aortic rings from young (Y) adult rats (maximum effect, 46.4+/-9.4% at 10(-5) mol/L, P<0.01). Similar vasorelaxation was elicited with the additional arginase inhibitors N-hydroxy-nor-L-arginine (nor-NOHA) and difluoromethylornithine (DFMO). This effect required intact endothelium and was prevented by 1H-oxadiazole quinoxalin-1-one (P<0.05 and P<0.001, respectively), a soluble guanylyl cyclase inhibitor. DFMO-elicited vasodilation was greater in old (O) compared with Y rat aortic rings (60+/-6% versus 39+/-6%, P<0.05). In addition, BEC restored depressed L-arginine (10(-4) mol/L)-dependent vasorelaxant responses in O rings to those of Y. Arginase activity and expression were increased in O rings, whereas NOS activity and cyclic GMP levels were decreased. BEC and DFMO suppressed arginase activity and restored NOS activity and cyclic GMP levels in O vessels to those of Y. CONCLUSIONS: These findings demonstrate that arginase modulates NOS activity, likely by regulating intracellular L-arginine availability. Arginase upregulation contributes to endothelial dysfunction of aging and may therefore be a therapeutic target.

Berkowitz, Dan E.; White, Ron; Li, Dechun; Minhas, Khalid M.; Cernetich, Amy; Kim, Soonyul; Burke, Sean; Shoukas, Artin A.; Nyhan, Daniel; Champion, Hunter C.; Hare, Joshua M.

2003-01-01

387

Estrogen protects peripheral and cerebral blood vessels from toxicity of Alzheimer peptide amyloid-beta and inflammatory reaction.  

PubMed

Due to increases in life expectancy, women are living 30 years or more beyond menopause. This has led to an increasing interest in the association between postmenopausal estrogen deficiency and degenerative diseases associated with aging such as cardiovascular disease, osteoporosis and dementia. Women are two times more likely to develop late-onset Alzheimer's disease (AD) than age-matched men. A large number of observational reports and a few randomized clinical trials have indicated that estrogen replacement therapy (ERT) may retard the development and severity of dementia in postmenopausal women. The mechanism underlying the protective action of estrogen in AD is under active investigation. A chronic inflammatory reaction mediated by abnormal deposition of proteins such as amyloid-beta (A beta) is central to the pathology of AD. We investigated the effect of low doses of conjugated estrogen (Premarin) in an animal model of A beta-induced vascular disruption and inflammatory reaction. This rodent model allows live videomicroscopic recording and electron microscopic analysis of peripheral vascular disruption and inflammatory reaction triggered by A beta. Estrogen prevented vascular deposition of A beta, endothelial and vessel wall disruption with plasma leakage, platelet and mast cell activation, and characteristic features of an inflammatory reaction: adhesion and transmigration of leukocytes. The beneficial effect was lost when estrogen treatment was discontinued. Estrogen also protected the cerebral blood vessels from endothelial dysfunction induced by A beta. This novel protective effect of estrogen against A beta cytotoxicity in peripheral and cerebral vasculature may contribute to the therapeutic efficacy of estrogen in AD and coronary vascular disease. PMID:10685397

Thomas, T; Rhodin, J A; Sutton, E T; Bryant, M W; Price, J M

1999-10-01

388

hsp70 mRNA temporal localization in rat skeletal myofibers and blood vessels post-exercise.  

PubMed

Rapid transcription of the survival transcript, inducible heat shock protein 70 (hsp70), is critical for mounting cytoprotection against severe cellular stress, like elevated temperature. Previous investigations have demonstrated that exercise-induced expression of Hsp70 protein occurs in a fiber-specific pattern; however, the activation pattern of hsp70 mRNA expression remains unclear in skeletal muscle. Consequentially, the temporal localization of hsp70 mRNA was characterized via in situ hybridization (ISH) experiments examining fast-muscle, white vastus: 1, 3, 10, and 24h after a single bout of intense treadmill running (1h, 30m/min, 6% grade) in rats. The role that the physiologic temperature stress associated with exercise (raising core body temperature to 40.0C for 15min (HS-40.0C)) might play in inducing hsp70 mRNA expression was also explored. In skeletal muscle myofibers (SkM), hsp70 mRNA ISH signal was observed to be concentrated in a punctate manner that was associated with nuclei post-exercise. HS-40C treatment produced minimal detectable hsp70 mRNA ISH signal in SkM. In large intermyofibrillar blood vessels (BV), peak hsp70 mRNA signal, distributed throughout the vessel wall, was observed 1h post-exercise. In BV, no differences in hsp70 mRNA signal were observed between HS-40C and EX-1h. Results indicate that the majority of hsp70 mRNA is retained in a perinuclear localization in SkM post-exercise. They further suggest a muscle-type specific time course for peak hsp70 mRNA expression. This investigation suggests that the physiologic rise in core temperature associated with exercise per se is not the key stimulus responsible for inducing hsp70 mRNA transcription in SkM. PMID:21953294

Silver, Jordan Thomas; Kowalchuk, Hana; Noble, Earl G

2012-01-01

389

Gonadotropin-releasing hormone neurons extend complex highly branched dendritic trees outside the blood-brain barrier.  

PubMed

GnRH neurons project axons to the median eminence to control pituitary release of gonadotropins and, as such, represent the principal output neurons of the neuronal network controlling fertility. It is well established that the GnRH neurons exhibit a simple bipolar morphology with one or two long dendrites. Using adult GnRH-green fluorescent protein transgenic mice and juxtacellular cell filling, we report here that a subpopulation of GnRH neurons located in the rostral preoptic area exhibit extremely complex branching dendritic trees that fill the organum vasculosum of the lamina terminalis (OVLT). The dendritic nature of these processes was demonstrated at both light and electron microscopic levels by the presence of spines, dendritic ultrastructure, and synapses. Further, electrophysiological recordings showed that GnRH neurons were excited by glutamate as well as kisspeptin puffed onto their dendrites located within the OVLT. Using iv injection of horseradish peroxidase, a molecule unable to penetrate the blood-brain barrier (BBB), we show that GnRH neuron cell bodies and dendrites within 100 ?m of the OVLT reside outside the BBB. Approximately 85% of GnRH neurons in this area express c-Fos at the time of the GnRH surge. These observations demonstrate that GnRH neurons extend complex, highly branched dendritic trees beyond the BBB into the OVLT, where they will be able to sense directly molecules circulating in the bloodstream. This indicates a new mechanism for the modulation of GnRH neurons that extends considerably the range of factors that are integrated by these neurons for the control of fertility. PMID:21791557

Herde, Michel K; Geist, Katrin; Campbell, Rebecca E; Herbison, Allan E

2011-10-01

390

Coadministration of branched-chain amino acids and lipopolysaccharide causes matrix metalloproteinase activation and blood-brain barrier breakdown.  

PubMed

Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a severe deficiency in the activity of the branched-chain ?-keto acid dehydrogenase complex, leading to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine. Infections have a significant role in precipitating acute metabolic decompensation in patients with MSUD; however, the mechanisms underlying the neurotoxicity in this disorder are poorly understood. In this study, we subjected rats to the coadministration of lipopolysaccharide (LPS), which is a major component of gram-negative bacteria cell walls, and high concentrations of BCAA (H-BCAA) to determine their effects on the permeability of the blood-brain barrier (BBB) and on the levels of matrix metalloproteinases (MMP-2 and MMP-9). Our results demonstrated that the coadministration of H-BCAA and LPS causes breakdown of the BBB and increases the levels of MMP-2 and MMP-9 in the hippocampus of these rats. On the other hand, examination of the cerebral cortex of the 10- and 30-day-old rats revealed a significant difference in Evan's Blue content after coadministration of H-BCAA and LPS, as MMP-9 levels only increased in the cerebral cortex of the 10-day-old rats. In conclusion, these results suggest that the inflammatory process associated with high levels of BCAA causes BBB breakdown. Thus, we suggest that BBB breakdown is relevant to the perpetuation of brain inflammation and may be related to the brain dysfunction observed in MSUD patients. PMID:24390570

Scaini, Giselli; Morais, Meline O S; Galant, Leticia S; Vuolo, Francieli; Dall'Igna, Dhbora M; Pasquali, Matheus A B; Ramos, Vitor M; Gelain, Daniel P; Moreira, Jose Claudio F; Schuck, Patrcia F; Ferreira, Gustavo C; Soriano, Francisco G; Dal-Pizzol, Felipe; Streck, Emilio L

2014-10-01

391

Reducing the data: Analysis of the role of vascular geometry on blood flow patterns in curved vessels  

NASA Astrophysics Data System (ADS)

Three-dimensional simulations of blood flow usually produce such large quantities of data that they are unlikely to be of clinical use unless methods are available to simplify our understanding of the flow dynamics. We present a new method to investigate the mechanisms by which vascular curvature and torsion affect blood flow, and we apply it to the steady-state flow in single bends, helices, double bends, and a rabbit thoracic aorta based on image data. By calculating forces and accelerations in an orthogonal coordinate system following the centreline of each vessel, we obtain the inertial forces (centrifugal, Coriolis, and torsional) explicitly, which directly depend on vascular curvature and torsion. We then analyse the individual roles of the inertial, pressure gradient, and viscous forces on the patterns of primary and secondary velocities, vortical structures, and wall stresses in each cross section. We also consider cross-sectional averages of the in-plane components of these forces, which can be thought of as reducing the dynamics of secondary flows onto the vessel centreline. At Reynolds numbers between 50 and 500, secondary motions in the directions of the local normals and binormals behave as two underdamped oscillators. These oscillate around the fully developed state and are coupled by torsional forces that break the symmetry of the flow. Secondary flows are driven by the centrifugal and torsional forces, and these are counterbalanced by the in-plane pressure gradients generated by the wall reaction. The viscous force primarily opposes the pressure gradient, rather than the inertial forces. In the axial direction, and depending on the secondary motion, the curvature-dependent Coriolis force can either enhance or oppose the bulk of the axial flow, and this shapes the velocity profile. For bends with little or no torsion, the Coriolis force tends to restore flow axisymmetry. The maximum circumferential and axial wall shear stresses along the centreline correlate well with the averaged in-plane pressure gradient and the radial displacement of the peak axial velocity, respectively. We conclude with a discussion of the physiological implications of these results.

Alastruey, Jordi; Siggers, Jennifer H.; Peiffer, Vronique; Doorly, Denis J.; Sherwin, Spencer J.

2012-03-01

392

Skeletal muscle fiber, nerve, and blood vessel breakdown in space-flown rats  

NASA Technical Reports Server (NTRS)

Histochemical and ultrastructural analyses were performed postflight on hind limb skeletal muscles of rats orbited for 12.5 days aboard the unmanned Cosmos 1887 biosatellite and returned to Earth 2 days before sacrifice. The antigravity adductor longus (AL), soleus, and plantaris muscles atrophied more than the non-weight-bearing extensor digitorum longus, and slow muscle fibers were more atrophic than fast fibers. Muscle fiber segmental necrosis occurred selectively in the AL and soleus muscles; primarily, macrophages and neutrophils infiltrated and phagocytosed cellular debris. Granule-rich mast cells were diminished in flight AL muscles compared with controls, indicating the mast cell secretion contributed to interstitial tissue edema. Increased ubiquitination of disrupted myofibrils implicated ubiquitin in myofilament degradation. Mitochondrial content and succinic dehydrogenase activity were normal, except for subsarcolemmal decreases. Myofibrillar ATPase activity of flight AL muscle fibers shifted toward the fast type. Absence of capillaries and extravasation of red blood cells indicated failed microcirculation. Muscle fiber regeneration from activated satellite cells was detected. About 17% of the flight AL end plates exhibited total or partial denervation. Thus, skeletal muscle weakness associated with spaceflight can result from muscle fiber atrophy and segmental necrosis, partial motor denervation, and disruption of the microcirculation.

Riley, D. A.; Ilyina-Kakueva, E. I.; Ellis, S.; Bain, J. L.; Slocum, G. R.; Sedlak, F. R.

1990-01-01

393

Localization of neuropeptide Y Y1 receptors in cerebral blood?vessels  

PubMed Central

The localization of neuropeptide Y (NPY) Y1 receptor (R) -like immunoreactivity (LI) has been studied in cerebral arteries and arterioles of the rat by immunohistochemistry using fluorescence, confocal, and electron microscopy. High levels of Y1-R-LI were observed in smooth muscle cells (SMCs) in the small arterioles of the pial arterial network, especially on the basal surface of the brain, and low levels in the major basal cerebral arteries. The levels of Y1-R-LI varied strongly between adjacent SMCs. Y1-R-LI was associated with small endocytosis vesicles, mainly on the outer surface of the SMCs, but also on their endothelial side and often laterally at the interface between two SMCs. NPY-immunoreactive (Ir) nerve fibers could not be detected in association with the Y1-R-rich small arterioles but only around arteries with low Y1-R levels. A dense network of central NPY-Ir nerve fibers in the superficial layers of the brain was lying close to the strongly Y1-R-Ir small arterioles. The results indicate that NPY has a profound effect on small arterioles of the brain acting on Y1-Rs, both on the peripheral and luminal side of the SMCs. However, the source of the endogenous ligand, NPY, remains unclear. NPY released from central neurons may play a role, in addition to