These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Cellular and molecular regulation of vascular permeability  

PubMed Central

Summary Vascular permeability is a highly coordinated process that integrates vesicular trafficking, complex junctional rearrangements, and refined cytoskeletal dynamics. In response to the extracellular environment, these three cellular activities have been previously assumed to work in parallel to regulate the passage of solutes between the blood and tissues. New developments in the area of vascular permeability, however have highlighted the interdependence between trans- and para-cellular pathways, the cross-communication between adherens and tight junctions, and the instructional role of pericytes on endothelial expression of barrier-related genes. Additionally, significant effort has been placed in understanding the molecular underpinings that contribute to barrier restoration following acute permeability events and in clarifying the importance of context-dependent signaling initiated by permeability mediators. Finally, recent findings have uncovered an unpredicted role for transcription factors in the coordination of vascular permeability and clarified how junctional complexes can transmit signals to the nucleus to control barrier function. The goal of this review is to provide a concise and updated view of vascular permeability, discuss the most recent advances in molecular and cellular regulation, and introduce integrated information on the central mechanisms involved in trans-endothelial transport. PMID:23389236

Goddard, Lauren M.; Iruela-Arispe, M. Luisa

2013-01-01

2

Vascular Permeability and Drug Delivery in Cancers  

PubMed Central

The endothelial barrier strictly maintains vascular and tissue homeostasis, and therefore modulates many physiological processes such as angiogenesis, immune responses, and dynamic exchanges throughout organs. Consequently, alteration of this finely tuned function may have devastating consequences for the organism. This is particularly obvious in cancers, where a disorganized and leaky blood vessel network irrigates solid tumors. In this context, vascular permeability drives tumor-induced angiogenesis, blood flow disturbances, inflammatory cell infiltration, and tumor cell extravasation. This can directly restrain the efficacy of conventional therapies by limiting intravenous drug delivery. Indeed, for more effective anti-angiogenic therapies, it is now accepted that not only should excessive angiogenesis be alleviated, but also that the tumor vasculature needs to be normalized. Recovery of normal state vasculature requires diminishing hyperpermeability, increasing pericyte coverage, and restoring the basement membrane, to subsequently reduce hypoxia, and interstitial fluid pressure. In this review, we will introduce how vascular permeability accompanies tumor progression and, as a collateral damage, impacts on efficient drug delivery. The molecular mechanisms involved in tumor-driven vascular permeability will next be detailed, with a particular focus on the main factors produced by tumor cells, especially the emblematic vascular endothelial growth factor. Finally, new perspectives in cancer therapy will be presented, centered on the use of anti-permeability factors and normalization agents. PMID:23967403

Azzi, Sandy; Hebda, Jagoda K.; Gavard, Julie

2013-01-01

3

Tonic regulation of vascular permeability  

PubMed Central

Our major theme is that the layered structure of the endothelial barrier requires continuous activation of signaling pathways regulated by S1P and intracellular cAMP. These pathways modulate the adherens junction, continuity of tight junction strands, and the balance of synthesis and degradation of glycocalyx components. We evaluate recent evidence that baseline permeability is maintained by constant activity of mechanisms involving the small GTPases Rap1 and Rac1. In the basal state, the barrier is compromised when activities of the small GTPases are reduced by low S1P supply or delivery. With inflammatory stimulus, increased permeability can be understood in part as the action of signaling to reduce Rap1 and Rac1 activation. With the hypothesis that microvessel permeability and selectivity under both normal and inflammatory conditions are regulated by mechanisms that are continuously active it follows that when S1P or intracellular cAMP are elevated at the time of inflammatory stimulus, they can buffer changes induced by inflammatory agents and maintain normal barrier stability. When endothelium is exposed to inflammatory conditions and subsequently exposed to elevated S1P or intracellular cAMP, the same processes restore the functional barrier by first reestablishing the adherens junction, then modulating tight junctions and glycocalyx. In more extreme inflammatory conditions, loss of the inhibitory actions of Rac1 dependent mechanisms may promote expression of more inflammatory endothelial phenotypes by contributing to the up-regulation of RhoA dependent contractile mechanisms and the sustained loss of surface glycocalyx allowing access of inflammatory cells to the endothelium. PMID:23374222

Curry, Fitz-Roy E.; Adamson, Roger H.

2014-01-01

4

Expression of vascular permeability factor (vascular endothelial growth factor) and its receptors in breast cancer  

Microsoft Academic Search

Solid tumors must induce a vascular stroma to grow beyond a minimal size, and the intensity of the angiogenic response has been correlated with prognosis in breast cancer patients. Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a secreted protein that has been implicated in tumor-associated angiogenesis. Vascular permeability factor directly stimulates endothelial cell growth

Lawrence F Brown; Brygida Berse; Robert W Jackman; Kathi Tognazzi; Anthony J Guidi; Harold F Dvorak; Donald R Senger; James L Connolly; Stuart J Schnitt

1995-01-01

5

Overexpression of Vascular Permeability Factor\\/Vascular Endothelial Growth Factor and its Receptors in Psoriasis  

Microsoft Academic Search

Summary Psoriatic skin is characterized by microvascular hyperpermeability and angioproliferation, but the mechanisms responsible are unknown. We report here that the hyperplastic epidermis of psoriatic skin expresses strikingly increased amounts of vascular permeability factor (VPF; vascular endothelial growth factor), a selective endothelial cell mitogen that enhances microvascular permeability. Moreover, two VPF receptors, kdr and fit-l, are overexpressed by papillary dermal

Michael Detmar; Lawrence F. Brown; Kevin P. Claffey; Kiang-Teck Yeo; Olivier Kocher; Robert W. Jackman; Brygida Berse; Harold F. Dvorak

1994-01-01

6

Galectin-1 induces vascular permeability through the neuropilin-1/vascular endothelial growth factor receptor-1 complex.  

PubMed

Galectin-1 (Gal-1) is a ?-galactoside-binding lectin that regulates endothelial cell migration, proliferation, and adhesion. However, the effect of Gal-1 on vascular permeability and the underlying mechanisms are unclear. We found that high Gal-1 expression was associated with elevated tumor vascular permeability in specimens of oral squamous cell carcinoma. Using transendothelial passage of FITC-dextran and a Miles assay, we demonstrated that Gal-1 increased vascular permeability extracellularly through its carbohydrate recognition domain. Mechanism dissection revealed that the neuropilin (NRP)-1/vascular endothelial growth factor receptor- (VEGFR)-1 complex was required for Gal-1-regulated vascular permeability. Activation of VEGFR-1 triggered activation of Akt which led to a reduction in vascular endothelial-cadherin at cell-cell junctions and resulted in cytoskeletal rearrangement. Both inhibition of Gal-1 secreted from cancer cells and administration of an anti-Gal-1 antibody in the tumor microenvironment suppressed tumor growth and vascular permeability in xenograft models. In conclusion, our results demonstrate a novel function of Gal-1 of increasing vascular permeability through the NRP-1/VEGFR1 and Akt signaling pathway and indicate that targeting Gal-1 by an anti-Gal-1 antibody is a feasible therapy for vascular hyperpermeability and cancer. PMID:24719187

Wu, Ming-Heng; Ying, Nien-Wen; Hong, Tse-Ming; Chiang, Wei-Fan; Lin, Yueh-Te; Chen, Yuh-Ling

2014-10-01

7

Endotoxin increases pulmonary vascular protein permeability in the dog  

SciTech Connect

Endotoxin increases pulmonary vascular permeability consistently in some species but fails to reliably cause injury in the dog. We wondered whether this phenomenon depended on the method of injury assessment, as others have relied on edema measurement; we quantified injury by monitoring the rate of extravascular protein accumulation. /sup 113m/In-labeled protein and /sup 99m/Tc-labeled erythrocytes were injected into anesthetized dogs and monitored by an externally placed lung probe. A protein leak index, the rate of extravascular protein accumulation, was derived from the rate of increase in lung protein counts corrected for changes in intravascular protein activity. After administration of Salmonella enteriditis endotoxin (4 micrograms/kg), the protein leak index was elevated 2.5-fold (41.1 +/- 4.6 X 10(-4) min-1) compared with control (16.0 +/- 2.8 X 10(-4) min-1). In contrast, wet-to-dry weight ratios failed to increase after endotoxin (4.6 +/- 0.8 vs. control values of 4.2 +/- 0.5 g/g dry bloodless lung). However, we observed that endotoxin increased lung dry weight (per unit body weight), which may have attenuated the change in wet-to-dry weight ratios. To determine whether low microvascular pressures following endotoxin attenuated edema formation, we increased pulmonary arterial wedge pressures in five dogs by saline infusion, which caused an increase in wet-to-dry weight ratios following endotoxin but no change in the five controls. We conclude that low dose endotoxin causes pulmonary vascular protein leak in the dog while edema formation is minimal or absent.

Welsh, C.H.; Dauber, I.M.; Weil, J.V.

1986-10-01

8

Increased Expression of Vascular Permeability Factor (Vascular Endothelial Growth Factor) in Bullous Pemphigoid, Dermatitis Herpetiformis, and Erythema Multiforme  

Microsoft Academic Search

Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), plays an important role in the increased vascular permeability and angiogenesis associated with many malignant tumors. In addition, VPF\\/VEGF is strongly expressed by epidermal keratinocytes in wound healing and psoriasis, disorders that are also characterized by increased microvascular permeability and angiogenesis. In this study, we investigated the expression

Lawrence F. Brown; Terence J. Harrist; Kiang-Teck Yeo; Mona Ståhle-Bäckdahl; Robert W. Jackman; Brygida Berse; Kathi Tognazzi; Harold F. Dvorak; Michael Detmar

1995-01-01

9

Vascular Permeability and Pathological Angiogenesis in Caveolin-1-Null Mice  

PubMed Central

Caveolin-1, the signature protein of endothelial cell caveolae, has many important functions in vascular cells. Caveolae are thought to be the transcellular pathway by which plasma proteins cross normal capillary endothelium, but, unexpectedly, cav-1?/? mice, which lack caveolae, have increased permeability to plasma albumin. The acute increase in vascular permeability induced by agents such as vascular endothelial growth factor (VEGF)-A occurs through venules, not capillaries, and particularly through the vesiculo-vacuolar organelle (VVO), a unique structure composed of numerous interconnecting vesicles and vacuoles that together span the venular endothelium from lumen to ablumen. Furthermore, the hyperpermeable blood vessels found in pathological angiogenesis, mother vessels, are derived from venules. The present experiments made use of cav-1?/? mice to investigate the relationship between caveolae and VVOs and the roles of caveolin-1 in VVO structure in the acute vascular hyperpermeability induced by VEGF-A and in pathological angiogenesis and associated chronic vascular hyperpermeability. We found that VVOs expressed caveolin-1 variably but, in contrast to caveolae, were present in normal numbers and with apparently unaltered structure in cav-1?/? mice. Nonetheless, VEGF-A-induced hyperpermeability was strikingly reduced in cav-1?/? mice, as was pathological angiogenesis and associated chronic vascular hyperpermeability, whether induced by VEGF-A164 or by a tumor. Thus, caveolin-1 is not necessary for VVO structure but may have important roles in regulating VVO function in acute vascular hyperpermeability and angiogenesis. PMID:19729487

Chang, Sung-Hee; Feng, Dian; Nagy, Janice A.; Sciuto, Tracey E.; Dvorak, Ann M.; Dvorak, Harold F.

2009-01-01

10

Vascular permeability and cell kinetics of ethylnitrosourea (ENU)-induced rat brain tumours  

Microsoft Academic Search

Summary Vascular permeability and proliferative activity of ethylnitrosourea (ENU)-induced rat brain tumours were studied by intravenous injection of Evans blue dye (EB) and by bromodeoxyuridine (BrdU) uptake examinations. Tumours induced by ENU showed various histologial types, and they were oligodendrogliomas, mixed oligo-astrocytomas, mixed oligo-ependymomas, astrocytomas, anaplastic astrocytomas, polymorphic gliomas, and ependymomas. The labelling indexes (LIs: the ratio of BrdU-labelled cells

T. Inoue; T. Tashima; S. Nishio; I. Takeshita; T. Iwaki; M. Fukui

1988-01-01

11

Gap Junction Protein Connexin43 Exacerbates Lung Vascular Permeability  

PubMed Central

Increased vascular permeability causes pulmonary edema that impairs arterial oxygenation and thus contributes to morbidity and mortality associated with Acute Respiratory Distress Syndrome and sepsis. Although components of intercellular adhesive and tight junctions are critical for maintaining the endothelial barrier, there has been limited study of the roles of gap junctions and their component proteins (connexins). Since connexins can modulate inflammatory signaling in other systems, we hypothesized that connexins may also regulate pulmonary endothelial permeability. The relationships between connexins and the permeability response to inflammatory stimuli were studied in cultured human pulmonary endothelial cells. Prolonged treatment with thrombin, lipopolysaccharide, or pathological cyclic stretch increased levels of mRNA and protein for the major connexin, connexin43 (Cx43). Thrombin and lipopolysaccharide both increased intercellular communication assayed by transfer of microinjected Lucifer yellow. Although thrombin decreased transendothelial resistance in these cells, the response was attenuated by pretreatment with the connexin inhibitor carbenoxolone. Additionally, the decreases of transendothelial resistance produced by either thrombin or lipopolysaccharide were attenuated by reducing Cx43 expression by siRNA knockdown. Both carbenoxolone and Cx43 knockdown also abrogated thrombin-induced phosphorylation of myosin light chain. Taken together, these data suggest that increased lung vascular permeability induced by inflammatory conditions may be amplified via increased expression of Cx43 and intercellular communication among pulmonary endothelial cells. PMID:24967639

O'Donnell, James J.; Birukova, Anna A.; Beyer, Eric C.; Birukov, Konstantin G.

2014-01-01

12

Gap junction protein connexin43 exacerbates lung vascular permeability.  

PubMed

Increased vascular permeability causes pulmonary edema that impairs arterial oxygenation and thus contributes to morbidity and mortality associated with Acute Respiratory Distress Syndrome and sepsis. Although components of intercellular adhesive and tight junctions are critical for maintaining the endothelial barrier, there has been limited study of the roles of gap junctions and their component proteins (connexins). Since connexins can modulate inflammatory signaling in other systems, we hypothesized that connexins may also regulate pulmonary endothelial permeability. The relationships between connexins and the permeability response to inflammatory stimuli were studied in cultured human pulmonary endothelial cells. Prolonged treatment with thrombin, lipopolysaccharide, or pathological cyclic stretch increased levels of mRNA and protein for the major connexin, connexin43 (Cx43). Thrombin and lipopolysaccharide both increased intercellular communication assayed by transfer of microinjected Lucifer yellow. Although thrombin decreased transendothelial resistance in these cells, the response was attenuated by pretreatment with the connexin inhibitor carbenoxolone. Additionally, the decreases of transendothelial resistance produced by either thrombin or lipopolysaccharide were attenuated by reducing Cx43 expression by siRNA knockdown. Both carbenoxolone and Cx43 knockdown also abrogated thrombin-induced phosphorylation of myosin light chain. Taken together, these data suggest that increased lung vascular permeability induced by inflammatory conditions may be amplified via increased expression of Cx43 and intercellular communication among pulmonary endothelial cells. PMID:24967639

O'Donnell, James J; Birukova, Anna A; Beyer, Eric C; Birukov, Konstantin G

2014-01-01

13

Strategies for improving chemotherapeutic delivery to solid tumors mediated by vascular permeability modulation  

NASA Astrophysics Data System (ADS)

An essential mode of distribution of blood-borne chemotherapeutic agents within a solid tumor is via the micro-circulation. Poor tumor perfusion, because of a lack of functional vasculature or a lack of microvessels, as well as low tumor vascular permeability, can prevent adequate deposition of even low molecular-weight agents into the tumor. The modulation of tumor vascular function and density can provides numerous strategies for improving intratumor deposition of chemotherapeutic agents. Here we investigated strategies to improve drug delivery to two tumor types that share in common poor drug delivery, but differ in the underlying cause. First, in an angiogenesis-driven brain tumor model of Glioblastoma, the vascular permeability barrier, along with poorly-functional vasculature, hinders drug delivery. A strategy of nanoparticle-based tumor 'priming' to attack the vascular permeability barrier, employing sterically stabilized liposomal doxorubicin (SSL-DXR), was investigated. Functional and histological evaluation of tumor vasculature revealed that after an initial period of depressed vascular permeability and vascular pruning 3--4 days after SSL-DXR administration, vascular permeability and perfusion were restored and then elevated after 5--7 days. As a result of tumor priming, deposition of subsequently-administered nanoparticles was enhanced, and the efficacy of temozolomide (TMZ), if administered during the window of elevated permeability, was increased. The sequenced regimen resulted in a persistent reduction of the tumor proliferative index and a 40% suppression of tumor volume, compared to animals that received both agents simultaneously. Second, in a hypovascular, pancreatic ductal adenocarcinoma model, disruption of tumor-stromal communication via sonic hedgehog (sHH) signaling pathway inhibition mediated an indirect vascular proliferation and a more than 2-fold increase in intratumor nanoparticle deposition. Enhanced delivery of SSL-DXR in tumors pre-treated with sHH-inhibitor led to a 90% lifespan extension in animals that received a single cycle of the combined regimen, and a 200% extension in animals receiving 3-cycles of treatment, compared to control animals or those receiving either of the agents alone. We surmise that direct or indirect modulation of tumor vasculature can provide new opportunities for combination therapies that could improve delivery and efficacy of both small- and large- molecular weight agents in treatment-resistant solid tumors.

Roy Chaudhuri, Tista

14

Regulation of Vascular Permeability by Sphingosine 1-Phosphate  

PubMed Central

A significant and sustained increase in vascular permeability is a hallmark of acute inflammatory diseases such as acute lung injury (ALI) and sepsis and is an essential component of tumor metastasis, angiogenesis, and atherosclerosis. Sphingosine 1-phosphate (S1P), an endogenous bioactive lipid produced in many cell types, regulates endothelial barrier function by activation of its G-protein coupled receptor SIP1. S1P enhances vascular barrier function through a series of profound events initiated by SIP1 ligation with subsequent downstream activation of the Rho family of small GTPases, cytoskeletal reorganization, adherens junction and tight junction assembly, and focal adhesion formation. Furthermore, recent studies have identified transactivation of SIP1 signaling by other barrier enhancing agents as a common mechanism for promoting endothelial barrier function. This review summarizes the state of our current knowledge about the mechanisms through which the S1P/SIP1 axis reduces vascular permeability, which remains an area of active investigation that will hopefully produce novel therapeutic agents in the near future. PMID:18973762

Wang, Lichun; Dudek, Steven M.

2009-01-01

15

Gap Junction Channel Modulates Pulmonary Vascular Permeability through Calcium in Acute Lung Injury: An Experimental Study  

Microsoft Academic Search

Background: Increased pulmonary vascular permeability is a hallmark of acute lung injury (ALI). Gap junction channels (GJCs) connect adjacent cells and facilitate ion exchange. It remained unclear whether GJCs modulate pulmonary permeability in ALI through intracellular calcium. Objectives: This study aimed to verify if GJCs in pulmonary microvessel endothelial cells (PMVECs) modulate pulmonary vascular permeability in ALI via intracellular calcium.

Jinzhou Zhang; Wen Wang; Jing Sun; Qiang Li; Jincheng Liu; Hailong Zhu; Tao Chen; Hongbing Wang; Shiqiang Yu; Guocheng Sun; Wensheng Chen; Dinghua Yi

2010-01-01

16

New sensitive fluorometric method for measurement of vascular permeability  

SciTech Connect

A sensitive fluorometric method has been developed for the measurement of vascular permeability in carrageenin air-pouch inflammation in rats. Fluorescein isothiocyanate-labeled bovine serum albumin (F-BSA) was used as a tracer. This fluorometric method is as simple and reliable as the method using radioiodine-labeled human serum albumin and has the advantages of low cost, no health hazard, and the fact that F-BSA can be stored over a long period. This fluorometric method is probably applicable to other inflammation models such as pleurisy and peritonitis in which inflammatory exudate can be collected.

Watanabe, K.; Nakagawa, H.; Tsurufuji, S.

1984-06-01

17

Enhanced vascular permeability induced in mice by larch arabinogalactan  

PubMed Central

Larch arabinogalactan AG(Lch) enhances vascular permeability when injected into normal mice. Increased vascular permeability is demonstrated by a marked blueing of the ears (BE) which follows the intravenous administration of AG(Lch) and Evans's blue dye. BE can be inhibited by D-galactose, derivatives of D-galactose, and oligosaccharides which contain D-galactose. The stereochemical specificity of inhibition, the specificity of desensitization of mice to AG(Lch) by repeated injections of this polysaccharide and the rapid elimination of [3H]AG(Lch) from the circulation, suggest that AG(Lch) may produce its biological effects by interacting with natural antibody. In vitro oxidation of the terminal non-reducing galactose residues of AG(Lch) by galactose oxidase completely destroys the ear blueing capacity of AG(Lch). BE induced by AG(Lch) in mice resembles anaphylactoid oedema elicited by dextran in rats in that it can be inhibited by the administration of (a) an anti-serotonin drug (UML 491), and (b) a hyperglycaemic inducing agent (alloxan). As in the dextran system in rats, a strain of mice has been found which does not react to AG(Lch). PMID:5484788

Kind, L. S.; Macedo-Sobrinho, B.; Ako, D.

1970-01-01

18

[Ultrastructure of glioma vessel--morphometric study for vascular permeability].  

PubMed

In this study we investigated the ultrastructure of human glioma capillaries in operated sample of low grade astrocytomas and malignant gliomas. Electronmicrographs of a total of 58 vessels were analyzed with computer assisted morphometry for ultrastructural evidence of permeability routes. All of these vessels were present in the marginal area of tumors devoid of necrosis, less than 10 micron in diameter and containing one nucleus at least on axial section. We found that: (1) The number of pinocytic vesicles was significantly higher in capillaries from malignant glioma (an average of 8.1 per 1 micron (2) cytoplasm) than those from low grade astrocytoma (an average of 4.0 per 1 micron (2) cytoplasm). In capillaries from malignant glioma, most of the pinocytic vesicles were arranged in the abluminal side of endothelium and some of them were fused each other. (2) Abnormal endothelial intercellular junctions which were defined as short tight junctions (less than or equal to 0.25 microns) were equally but infrequently seen in low grade astrocytomas and malignant gliomas. (3) Fenestrations in the endothelium were not seen. Therefore we suggest that the high vascular permeability and resultant brain edema in malignant gliomas is likely to increased pinocytic vesicles and rare but abnormal inter endothelial junctions. PMID:2054222

Takano, S; Yoshii, Y; Nose, T

1991-01-01

19

Vasoregulin, a glucocorticoid-inducible vascular permeability inhibitory protein.  

PubMed

A vascular permeability inhibitory protein 'Vasoregulin' was induced by dexamethasone and other glucocorticoids in Namalva cells. Precipitates produced by trichloroacetic acid from cultured supernatant (crude released vasoregulin) suppressed serotonin-induced paw edema of mice (ID30 = 750 micrograms/mouse) when dosed 30 min. before serotonin. Carrageenan paw edema of rats was also suppressed (ID30 = 9 mg/rat, s.c. and i.p., not by oral dosing) when the compound was injected at the same time as carrageenan and the edema determined after 3 hrs. The possible effect of glucocorticoid itself being contained in the vasoregulin preparation was excluded. The presence of Cu, Zn-superoxide dismutase (SOD), spermidine and spermine also gave good yields of vasoregulin in culture; SOD protected the inactivation of vasoregulin from superoxide radical in vitro. Vasoregulin partially purified by Sephadex G-75 columns had no malonaldehyde-formation inhibitory capacity. Thus, vasoregulin is a glucocorticoid-inducible anti-inflammatory protein which differs from lipocortin. PMID:3008526

Oyanagui, Y; Suzuki, S

1986-01-01

20

A noninvasive technique for monitoring lung vascular permeability in man.  

PubMed

Increased microvascular permeability resulting in increased plasma protein extravasation is the hallmark of acute inflammatory oedema and hence radiolabelled proteins can be used to monitor this process. The adult respiratory distress syndrome (ARDS) is characterized by acute inflammatory oedema and thus provides an ideal model for studying this type of oedema in the human lung. A noninvasive technique applicable to the intensive care unit has been developed for monitoring the pulmonary accumulation of the plasma protein transferrin. Transferrin was radiolabelled in vivo with indium-113m and its accumulation was monitored using a portable probe radiation detector. After correcting for changes in intrathoracic blood distribution, by simultaneously monitoring the accumulation of technetium-99m-labelled red blood cells, an index of plasma protein accumulation was calculated. In all patients with established ARDS (n = 10) the index values were greater than 1.0 X 10(-3) min-1 and these were clearly separate from the values of less than 0.5 X 10(-3) min-1 in all healthy volunteers (n = 5; P less than 0.001). The technique can clearly detect raised plasma protein accumulation indices in the lungs of patients with established inflammatory oedema of ARDS and hence may provide a pharmacological tool for the rapid evaluation in these conditions of the effects of drugs (like corticosteroids) which are known to modulate inflammatory oedema. PMID:3039429

Basran, G S; Byrne, A J; Hardy, J G

1985-01-01

21

Role of platelets in maintenance of pulmonary vascular permeability to protein  

SciTech Connect

The authors examined the role of platelets in maintenance of pulmonary vascular integrity by inducing thrombocytopenia in sheep using antiplatelet serum (APS). A causal relationship between thrombocytopenia and increase in pulmonary vascular permeability was established by platelet repletion using platelet-rich plasma (PRP). Sheep were chronically instrumented and lung lymph fistulas prepared to monitor pulmonary lymph flow (Q{sub lym}). A balloon catheter was positioned in the left atrium to assess pulmonary vascular permeability to protein after raising the left atrial pressure (P{sub la}). Thrombocytopenia was maintained for 3 days by daily intramuscular APS injections. In studies using cultured bovine pulmonary artery endothelial monolayers, transendothelia permeability of {sup 125}I-labeled albumin was reduced 50 and 95%, respectively, when 2.5 {times} 10{sup 7} or 5 {times} 10{sup 7} platelets were added onto endothelial monolayers. However, addition of 5 {times} 10{sup 6} platelets or 5 {times} 10{sup 7} red blood cells did not reduce endothelial monolayer albumin permeability. Results indicate that platelets are required for the maintenance of pulmonary vascular permeability. Reduction in permeability appears to involve an interaction of platelets with the endothelium.

Lo, S.K.; Burhop, K.E.; Kaplan, J.E.; Malik, A.B. (Albany Medical College of Union Univ., NY (USA))

1988-04-01

22

Occludin Phosphorylation and Ubiquitination Regulate Tight Junction Trafficking and Vascular Endothelial Growth Factor-induced Permeability*  

PubMed Central

Vascular endothelial growth factor (VEGF) alters tight junctions (TJs) and promotes vascular permeability in many retinal and brain diseases. However, the molecular mechanisms of barrier regulation are poorly understood. Here we demonstrate that occludin phosphorylation and ubiquitination regulate VEGF-induced TJ protein trafficking and concomitant vascular permeability. VEGF treatment induced TJ fragmentation and occludin trafficking from the cell border to early and late endosomes, concomitant with increased occludin phosphorylation on Ser-490 and ubiquitination. Furthermore, both co-immunoprecipitation and immunocytochemistry demonstrated that VEGF treatment increased the interaction between occludin and modulators of intracellular trafficking that contain the ubiquitin interacting motif, including Epsin-1, epidermal growth factor receptor pathway substrate 15 (Eps15), and hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs). Inhibiting occludin phosphorylation by mutating Ser-490 to Ala suppressed VEGF-induced ubiquitination, inhibited trafficking of TJ proteins, and prevented the increase in endothelial permeability. In addition, an occludin-ubiquitin chimera disrupted TJs and increased permeability without VEGF. These data demonstrate a novel mechanism of VEGF-induced occludin phosphorylation and ubiquitination that contributes to TJ trafficking and subsequent vascular permeability. PMID:19478092

Murakami, Tomoaki; Felinski, Edward A.; Antonetti, David A.

2009-01-01

23

Decreased KRIT1 expression leads to increased vascular permeability and modifies inflammatory responses in vivo  

PubMed Central

Objective The regulation of vascular permeability, leukocyte trafficking, and the integrity of endothelial cell-cell contacts are closely linked by a complex mechanism of inter-regulation. Here we investigate the role of KRIT1, an adherens junction accessory protein required for cell-cell junction stability, in the regulating these vascular functions. Methods and Results Krit1+/? mice exhibited an enhanced edematous response to the complex inflammatory stimuli found in the passive K/BxN model of inflammatory arthritis and the murine air pouch model, yet leukocyte infiltration was unchanged. Correspondingly, reduced KRIT1 expression increased baseline arteriole and venule permeability 2-fold over that of wildtype littermates, as measured by intravital microscopy of the intact cremaster muscle vascular network, but this increase was not accompanied by increased leukocyte extravasation or activation. Direct stimulation with tumor necrosis factor–? induced increased permeability in wildtype mice, but surprisingly, no increase over baseline levels was observed in Krit1+/? mice, despite extensive leukocyte activation. Finally, adoptive transfer of Krit1+/? bone marrow failed to increase permeability in wildtype mice. However, reduced expression of KRIT1 in the hematopoietic lineage dampened the differences observed in baseline permeability. Conclusions Taken together, our data indicate an integral role for KRIT1 in microvessel homeostasis and the vascular response to inflammation. PMID:22922958

Corr, Maripat; Lerman, Irina; Keubel, Julia M.; Ronacher, Lisa; Misra, Ravi; Lund, Frances; Sarelius, Ingrid H.; Glading, Angela J.

2012-01-01

24

Functions of Type II Pneumocyte-Derived Vascular Endothelial Growth Factor in Alveolar Structure, Acute Inflammation, and Vascular Permeability  

PubMed Central

Vascular endothelial growth factor-A (VEGF) is a potent regulator of vascular permeability, inflammatory response, and cell survival in the lung. To explore the functions of VEGF produced locally in type II pneumocytes, we generated mice with a conditional deletion of VEGF-A using Cre recombinase driven by the human surfactant protein C (SPC) promoter. In 7- to 10-week-old VEGF-knockout (SPC-VEGF-KO) mice, lung histology and physiology were essentially normal, except for higher dynamic lung compliance and lower pulmonary vascular permeability. Emphysema was seen in 28- to 32-week-old animals. To investigate the role of type II pneumocyte-derived VEGF in acute lung injury, we challenged 7- to 10-week-old SPC-VEGF-KO mice and their wild-type littermates with intestinal ischemia-reperfusion. Bronchoalveolar lavage fluid total cell count, pulmonary permeability, and lung injury score were significantly attenuated, and total lung VEGF levels were significantly lower in SPC-VEGF-KO mice compared with wild-type controls. In SPC-VEGF-KO mice, activated caspase 3-positive type II epithelial cells were increased after intestinal ischemia-reperfusion, even though there was no significant difference in the total number of cells positive for terminal deoxynucleotidyl transferase dUTP nick-end labeling. We conclude that VEGF in type II cells helps protect alveolar epithelial cells from caspase-dependent apoptosis. However, VEGF produced from type II cells may contribute to increased vascular permeability during acute lung injury. PMID:20167862

Mura, Marco; Binnie, Matthew; Han, Bing; Li, Chengjin; Andrade, Cristiano F.; Shiozaki, Atsushi; Zhang, Yu; Ferrara, Napoleone; Hwang, David; Waddell, Thomas K.; Keshavjee, Shaf; Liu, Mingyao

2010-01-01

25

Endothelial domes encapsulate adherent neutrophils and minimize increases in vascular permeability in paracellular and transcellular emigration.  

PubMed

Local edema, a cardinal sign of inflammation associates closely with neutrophil emigration. Neutrophil emigration has been described to occur primarily through endothelial junctions (paracellular) and more rarely directly through endothelial cells (transcellular). Recently, we reported that unlike in wild-type (wt) mice, Mac-1-/- (CD11b) neutrophils predominantly emigrated transcellularly and was significantly delayed taking 20-30 min longer than the paracellular emigration (wt). In the present study we noted significant anatomical disruption of the endothelium and hypothesized that transcellular emigration would greatly increase vascular permeability. Surprisingly, despite profound disruption of the endothelial barrier as the neutrophils moved through the cells, the changes in vascular permeability during transcellular emigration (Mac-1-/-) were not increased more than in wt mice. Instead increased vascular permeability completely tracked the number of emigrated cells and as such, permeability changes were delayed in Mac-1-/- mice. However, by 60 min neutrophils from both sets of mice were emigrating in large numbers. Electron-microscopy and spinning disk multichannel fluorescence confocal microscopy revealed endothelial docking structures that progressed to dome-like structures completely covering wt and Mac-1-/- neutrophils. These domes completely enveloped the emigrating neutrophils in both wt and Mac-1-/- mice making the mode of emigration underneath these structures extraneous to barrier function. In conclusion, predominantly paracellular versus predominantly transcellular emigration does not affect vascular barrier integrity as endothelial dome-like structures retain barrier function. PMID:18297135

Phillipson, Mia; Kaur, Jaswinder; Colarusso, Pina; Ballantyne, Christie M; Kubes, Paul

2008-01-01

26

A new glioma model in rat: The C6 spheroid implantation technique permeability and vascular characterization  

Microsoft Academic Search

The C6 spheroid implantation glioma model is a simple, easily reproduced model for primary gliomas in which C6 astrocytoma cells are grown in vitro as spheroids and subsequently implanted into the brains of Sprague Dawley rat hosts. This report describes the growth, histology, vessel architecture and vascular permeability of the resulting tumors. The appearance of the tumor was investigated by

Catherine L. Farrell; Patricia A. Stewart; Rolando F. Del Maestro

1987-01-01

27

A Neurodegenerative Vascular Burden Index and the Impact on Cognition  

PubMed Central

A wide range of vascular burden factors has been identified to impact vascular function and structure as indicated by carotid intima–media thickness (IMT). On the basis of their impact on IMT, vascular factors may be selected and clustered in a vascular burden index (VBI). Since many vascular factors increase the risk of Alzheimer’s disease (AD), a multifactorial neurodegenerative VBI may be related to early pathological processes in AD and cognitive decline in its preclinical stages. We investigated an elderly cohort at risk for neurodegeneration (TREND study, n?=?1102) for the multifactorial influence of vascular burden factors on IMT measured by ultrasound. To create a VBI for this cohort, vascular factors and their definitions (considering medical history, medication, and/or blood marker data) were selected based on their statistical effects on IMT in multiple regressions including age and sex. The impact of the VBI on cognitive performance was assessed using the Trail-Making Test (TMT) and the consortium to establish a registry for Alzheimer’s disease (CERAD) neuropsychological battery. IMT was significantly predicted by age (standardized ??=?0.26), sex (0.09; males?>?females) and the factors included in the VBI: obesity (0.18), hypertension (0.14), smoking (0.08), diabetes (0.07), and atherosclerosis (0.05), whereas other cardiovascular diseases or hypercholesterolemia were not significant. Individuals with 2 or more VBI factors compared to individuals without had an odds ratio of 3.17 regarding overly increased IMT ( ??1.0?mm). The VBI showed an impact on executive control [log(TMT B?A), p?=?0.047] and a trend toward decreased global cognitive function (CERAD total score, p?=?0.057) independent of age, sex, and education. A VBI established on the basis of IMT may help to identify individuals with overly increased vascular burden linked to decreased cognitive function indicating neurodegenerative processes. The longitudinal study of this risk cohort will reveal the value of the VBI as prodromal marker for cognitive decline and AD. PMID:25071568

Heinzel, Sebastian; Liepelt-Scarfone, Inga; Roeben, Benjamin; Nasi-Kordhishti, Isabella; Suenkel, Ulrike; Wurster, Isabel; Brockmann, Kathrin; Fritsche, Andreas; Niebler, Raphael; Metzger, Florian G.; Eschweiler, Gerhard W.; Fallgatter, Andreas J.; Maetzler, Walter; Berg, Daniela

2014-01-01

28

Evaluation of Damsites Groutability Using Secondary Permeability Index, Rock Classification (Case Studies)  

Microsoft Academic Search

Problem statement: The dam body and foundation seepage is one of the important points in design parameters. This index is related to the permeability. There fore permeability is one of the basic parameter in design grout curtain, prevent wa ter escape from foundation and avoid negative seepage pressure in borrow materials, so grouting i s used. Grouting means injected materials

R. Ajalloeian; F. Moein

2009-01-01

29

Histamine H3 receptors regulate vascular permeability changes in the skin of mast cell-deficient mice.  

PubMed

The participation of histamine H(3) receptors in the regulation of skin vascular permeability changes in mast cell-deficient mice was studied. Although intradermal injection of histamine H(3) antagonists, iodophenpropit and clobenpropit, at a dose of 100 nmol/site caused significant increases in skin vascular permeability in both mast cell-deficient (WBB6F1 W/W(v)) and wild-type (WBB6F1 +/+) mice, this response was significantly lower in mast cell-deficient mice than in the wild-type controls. Histamine also caused dose-related increases in skin vascular permeability in both wild-type and mast cell-deficient mice. Significant effects were observed at doses of 10 and 100 nmol/site, and no significant difference in skin vascular permeability was observed between mast cell-deficient and wild-type mice. However, histamine contents of dorsal skin in mast cell-deficient mice were significantly lower than in wild-type mice. In addition, the H(1) antagonists diphenhydramine and chlorpheniramine and the NK(1) antagonists, L-732,138 and L-733,060, were able to antagonize H(3) antagonist-induced skin vascular permeability. These results indicated that blockade of H(3) receptors by H(3) antagonists induce skin vascular permeability through mast cell-dependent mechanisms. In addition, histamine and, to a lesser extent substance P are involved in the reaction. PMID:14555281

Hossen, Maria Alejandra; Fujii, Yoko; Sugimoto, Yukio; Kayasuga, Ryoji; Kamei, Chiaki

2003-11-01

30

Podocalyxin Regulates Murine Lung Vascular Permeability by Altering Endothelial Cell Adhesion  

PubMed Central

Despite the widespread use of CD34-family sialomucins (CD34, podocalyxin and endoglycan) as vascular endothelial cell markers, there is remarkably little known of their vascular function. Podocalyxin (gene name Podxl), in particular, has been difficult to study in adult vasculature as germ-line deletion of podocalyxin in mice leads to kidney malformations and perinatal death. We generated mice that conditionally delete podocalyxin in vascular endothelial cells (Podxl?EC mice) to study the homeostatic role of podocalyxin in adult mouse vessels. Although Podxl?EC adult mice are viable, their lungs display increased lung volume and changes to the matrix composition. Intriguingly, this was associated with increased basal and inflammation-induced pulmonary vascular permeability. To further investigate the etiology of these defects, we isolated mouse pulmonary endothelial cells. Podxl?EC endothelial cells display mildly enhanced static adhesion to fibronectin but spread normally when plated on fibronectin-coated transwells. In contrast, Podxl?EC endothelial cells exhibit a severely impaired ability to spread on laminin and, to a lesser extent, collagen I coated transwells. The data suggest that, in endothelial cells, podocalyxin plays a previously unrecognized role in maintaining vascular integrity, likely through orchestrating interactions with extracellular matrix components and basement membranes, and that this influences downstream epithelial architecture. PMID:25303643

Debruin, Erin J.; Hughes, Michael R.; Sina, Christina; Liu, Alex; Cait, Jessica; Jian, Zhiqi; Lopez, Martin; Lo, Bernard; Abraham, Thomas; McNagny, Kelly M.

2014-01-01

31

Intravital lectin perfusion analysis of vascular permeability in human micro- and macro- blood vessels.  

PubMed

We previously applied intravital lectin perfusion in mouse models to elucidate mechanisms underlying vascular permeability. The present work transfers this technique to human models, analysing vascular permeability in macro- and microvessels. Human vascular endothelial surface carbohydrate biochemistry differs significantly from its murine counterpart, lacking alpha-galactosyl epitopes and expressing the L-fucose moiety in the glycocalyx; the poly-N-lactosamine glycan backbone is common to all mammals. We examined extensively lectin binding specificities in sections and in vivo, and then applied the poly-N-lactosamine-specific lectin LEA and the L-fucose-specific lectin UEA-I in human intravital perfusions. Transendothelial transport differed in macrovessels and microvessels. In microvessels of adult human fat tissue, rectal wall and rectal carcinomas, slow transendothelial transport by vesicles was followed by significant retention at the subendothelial basement membrane; paracellular passage was not observed. Passage time exceeded 1 h. Thus we found barrier mechanisms resembling those we described previously in murine tissues. In both adult and fetal macrovessels, the vena saphena magna and the umbilical vein, respectively, rapid passage across the endothelial lining was observed, the tracer localising completely in the subendothelial tissues within 15 min; vesicular transport was more rapid than in microvessels, and retention at the subendothelial basement membrane briefer. PMID:11702193

Debbage, P L; Sölder, E; Seidl, S; Hutzler, P; Hugl, B; Ofner, D; Kreczy, A

2001-10-01

32

Vascular endothelial growth factors enhance the permeability of the mouse blood-brain barrier.  

PubMed

The blood-brain barrier (BBB) impedes entry of many drugs into the brain, limiting clinical efficacy. A safe and efficient method for reversibly increasing BBB permeability would greatly facilitate central nervous system (CNS) drug delivery and expand the range of possible therapeutics to include water soluble compounds, proteins, nucleotides, and other large molecules. We examined the effect of vascular endothelial growth factor (VEGF) on BBB permeability in Kunming (KM) mice. Human VEGF165 was administered to treatment groups at two concentrations (1.6 or 3.0 µg/mouse), while controls received equal-volume saline. Changes in BBB permeability were measured by parenchymal accumulation of the contrast agent Gd-DTPA as assessed by 7 T magnetic resonance imaging (MRI). Mice were then injected with Evans blue, sacrificed 0.5 h later, and perfused transcardially. Brains were removed, fixed, and sectioned for histological study. Both VEGF groups exhibited a significantly greater signal intensity from the cerebral cortex and basal ganglia than controls (P<0.001). Evans blue fluorescence intensity was higher in the parenchyma and lower in the cerebrovasculature of VEGF-treated animals compared to controls. No significant brain edema was observed by diffusion weighted MRI (DWI) or histological staining. Exogenous application of VEGF can increase the permeability of the BBB without causing brain edema. Pretreatment with VEGF may be a feasible method to facilitate drug delivery into the CNS. PMID:24551038

Jiang, Shize; Xia, Rui; Jiang, Yong; Wang, Lei; Gao, Fabao

2014-01-01

33

Effect of Ultrasound on the Permeability of Vascular Wall to Nanoemulsion Droplets  

PubMed Central

The effect of ultrasound on the permeability of blood vessels to nanoemulsion droplets was investigated using excised mouse carotid arteries as model blood vessels. Perfluorocarbon nanodroplets were formed by perfluoro-15-crown-5-ether (PFCE) and stabilized by poly(ethylene oxide)-co-poly(D,L-lactide) (PEG-PDLA) block copolymer shells. Nanodroplet fluorescence was imparted by interaction with FITC-dextran (molecular weight of 70,000 Da). The permeability of carotid arteries to nanodroplets was studied in the presence or absence of continuous wave (CW) or pulsed therapeutic 1-MHz ultrasound. The data showed that the application of ultrasound resulted in permeabilization of the vascular wall to nanodroplets. The effect of CW ultrasound was substantially stronger than that of pulsed ultrasound of the same total energy. No effect of blood vessel pre-treatment with ultrasound was observed. PMID:23849384

Thakkar, Dhaval; Gupta, Roohi; Monson, Kenneth; Rapoport, Natalya

2013-01-01

34

Effect of ultrasound on the permeability of vascular wall to nano-emulsion droplets.  

PubMed

The effect of ultrasound on the permeability of blood vessels to nano-emulsion droplets was investigated using excised mouse carotid arteries as model blood vessels. Perfluorocarbon nano-droplets were formed by perfluoro-15-crown-5-ether and stabilized by poly(ethylene oxide)-co-poly(DL-lactide) block co-polymer shells. Nano-droplet fluorescence was imparted by interaction with fluorescein isothiocyanate-dextran (molecular weight = 70,000 Da). The permeability of carotid arteries to nano-droplets was studied in the presence and absence of continuous wave or pulsed therapeutic 1-MHz ultrasound. The data indicated that the application of ultrasound resulted in permeabilization of the vascular wall to nano-droplets. The effect of continuous wave ultrasound was substantially stronger than that of pulsed ultrasound of the same total energy. No effect of blood vessel pre-treatment with ultrasound was observed. PMID:23849384

Thakkar, Dhaval; Gupta, Roohi; Monson, Kenneth; Rapoport, Natalya

2013-10-01

35

Sphingosine-1-phosphate modulates vascular permeability and cell recruitment in acute inflammation in vivo.  

PubMed

The sphingosine kinase (SPK)/sphingosine-1-phosphate (S1P) pathway recently has been associated with a variety of inflammatory-based diseases. The majority of these studies have been performed in vitro. Here, we have addressed the relevance of the SPK/S1P pathway in the acute inflammatory response in vivo by using different well known preclinical animal models. The study has been performed by operating a pharmacological modulation using 1) L-cycloserine and DL-threo-dihydrosphingosine (DTD), S1P synthesis inhibitors or 2) 2-undecyl-thiazolidine-4-carboxylic acid (BML-241) and N-(2,6-dichloro-4-pyridinyl)-2-[1,3-dimethyl-4-(1-methylethyl)-1H-pyrazolo[3,4-b]pyridin-6-yl]-hydrazinecarboxamide (JTE-013), specific S1P(2) and S1P(3) receptor antagonists. After local injection of carrageenan in mouse paw S1P release significantly increases locally and decreases during the resolution phase. Expression of SPKs and S1P(2) and S1P(3) receptors is increased in inflamed tissues. Administration of L-cycloserine or DTD caused a significant anti-inflammatory effect. By using different animal models we have also demonstrated that the SPK/S1P pathway contributes to changes in vascular permeability and promotes cell recruitment. The S1P effect on cell recruitment results is receptor-mediated because both JTE-013 and BML-241 inhibited zymosan-induced cell chemotaxis without effect on vascular leakage. Conversely, changes in vascular permeability involve mainly SPK activity, because compound 48/80-induced vascular leakage was significantly inhibited by DTD. In conclusion, the SPK/S1P pathway is involved in acute inflammation and could represent a valuable therapeutic target for developing a new class of anti-inflammatory drugs. PMID:21421740

Roviezzo, Fiorentina; Brancaleone, Vincenzo; De Gruttola, Luana; Vellecco, Valentina; Bucci, Mariarosaria; D'Agostino, Bruno; Cooper, Dianne; Sorrentino, Raffaella; Perretti, Mauro; Cirino, Giuseppe

2011-06-01

36

Vascular permeability factor/vascular endothelial growth factor and the significance of microvascular hyperpermeability in angiogenesis.  

PubMed

This Chapter has reviewed the literature concerning VPF/VEGF as a potent vascular permeabilizing cytokine. In accord with this important role, microvessels have been found to be hyperpermeable to plasma proteins and other circulating macromolecules at sites where VPF/VEGF and its receptors are overexpressed, i.e., in tumors, healing wounds, retinopathies, many important inflammatory conditions and in certain physiological processes, such as ovulation and corpus luteum formation. Moreover, microvascular hyperpermeability to plasma proteins was shown to have an important consequence: the laying down of a fibrin-rich extracellular matrix. This provisional matrix, in turn, favors and supports the ingrowth of fibroblasts and endothelial cells which, together, transform the provisional matrix into the mature stroma characteristic of tumors and healed wounds. Finally, we have considered the pathways by which these and other circulating macromolecules cross the endothelium of normal and VPF/VEGF-permeabilized microvessels. These pathways include VVOs and trans-endothelial openings that have been variously interpreted as inter-endothelial cell gaps or trans-endothelial cell pores. At least some trans-endothelial cell pores may arise from VVOs. In conclusion, these data provide new insights into the mechanisms of angiogenesis and stroma formation, insights which are potentially applicable to a wide variety of disease states and which may lead to identification of new targets for therapeutic intervention. PMID:9893348

Dvorak, H F; Nagy, J A; Feng, D; Brown, L F; Dvorak, A M

1999-01-01

37

Synthesis, Storage, and Release of Vascular Endothelial Growth Factor\\/Vascular Permeability Factor (VEGF\\/VPF) by Human Mast Cells: Implications for the Biological Significance of VEGF206  

Microsoft Academic Search

Mast cells have been implicated in various diseases that are accompanied by neovascu- larization. The exact mechanisms by which mast cells might mediate an angiogenic response, however, are unclear and therefore, we have investigated the possible expres- sion of vascular endothelial growth factor\\/vascular permeability factor (VEGF\\/VPF) in the human mast cell line HMC-1 and in human skin mast cells. Reverse

Andreas Grutzkau; Sabine Kruger-Krasagakes; Hans Baumeister; Constanze Schwarz; Heidi Kogel; Pia Welker; Undine Lippert; Beate M. Henz; Annelie Moller

38

Gold nanoparticles inhibit vascular endothelial growth factor-induced angiogenesis and vascular permeability via Src dependent pathway in retinal endothelial cells  

Microsoft Academic Search

The purpose of this study was to investigate the effect of gold nanoparticles on the signaling cascade related to angiogenesis\\u000a and vascular permeability induced by Vascular Endothelial Growth Factor (VEGF) in Bovine retinal endothelial cells (BRECs).\\u000a The effect of VEGF and gold nanoparticles on cell viability, migration and tubule formation was assessed. PP2 (Src Tyrosine\\u000a Kinase inhibitor) was used as

Kalimuthu Kalishwaralal; Sardarpasha Sheikpranbabu; Selvaraj BarathManiKanth; Ravinarayanan Haribalaganesh; Sureshbabu Ramkumarpandian; Sangiliyandi Gurunathan

2011-01-01

39

Effect of sulodexide on endothelial glycocalyx and vascular permeability in patients with type 2 diabetes mellitus  

PubMed Central

Aims/hypothesis Endothelial glycocalyx perturbation contributes to increased vascular permeability. In the present study we set out to evaluate whether: (1) glycocalyx is perturbed in individuals with type 2 diabetes mellitus, and (2) oral glycocalyx precursor treatment improves glycocalyx properties. Methods Male participants with type 2 diabetes (n?=?10) and controls (n?=?10) were evaluated before and after 2 months of sulodexide administration (200 mg/day). The glycocalyx dimension was estimated in two different vascular beds using sidestream dark field imaging and combined fluorescein/indocyanine green angiography for sublingual and retinal vessels, respectively. Transcapillary escape rate of albumin (TERalb) and hyaluronan catabolism were assessed as measures of vascular permeability. Results Both sublingual dimensions (0.64 [0.57–0.75] ?m vs 0.78 [0.71–0.85] ?m, p?vascular permeability, which are partially restored following sulodexide administration. Further studies are warranted to determine whether long-term treatment with sulodexide has a beneficial effect on cardiovascular risk. Trial registration www.trialregister.nl NTR780/http://isrctn.org ISRCTN82695186 Funding An unrestricted Novartis Foundation for Cardiovascular Excellence grant (2006) to M. Nieuwdorp/E. S. G. Stroes, Dutch Heart Foundation (grant number 2005T037) PMID:20865240

Broekhuizen, L. N.; Lemkes, B. A.; Mooij, H. L.; Meuwese, M. C.; Verberne, H.; Holleman, F.; Schlingemann, R. O.; Nieuwdorp, M.; Vink, H.

2010-01-01

40

The diaphragms of fenestrated endothelia - gatekeepers of vascular permeability and blood composition  

PubMed Central

SUMMARY Fenestral and stomatal diaphragms are endothelial subcellular structures of unknown function that form on organelles implicated in vascular permeability: fenestrae, transendothelial channels and caveolae. PV1 protein is required for diaphragm formation in vitro. Here, we report that deletion of the PV1-encoding Plvap gene in mice results in the absence of diaphragms and decreased survival. Loss of diaphragms did not affect the fenestrae and transendothelial channels formation but disrupted the barrier function of fenestrated capillaries causing a major leak of plasma proteins. This disruption results in early death of animals due to severe non-inflammatory protein loosing enteropathy. Deletion of PV1 in endothelium, but not the hematopoietic compartment, recapitulates the phenotype of global PV1 deletion, whereas endothelial reconstitution of PV1 rescues the phenotype. Taken together, these data provide genetic evidence for the critical role of the diaphragms in fenestrated capillaries in the maintenance of blood composition. PMID:23237953

Stan, Radu V.; Tse, Dan; Deharvengt, Sophie J.; Smits, Nicole C.; Xu, Yan; Luciano, Marcus R.; McGarry, Caitlin L.; Buitendijk, Maarten; Nemani, Krishnamurthy V.; Elgueta, Raul; Kobayashi, Takashi; Shipman, Samantha L.; Moodie, Karen L.; Daghlian, Charles P.; Ernst, Patricia A.; Lee, Hong-Kee; Suriawinata, Arief A.; Schned, Alan R.; Longnecker, Daniel S.; Fiering, Steven N.; Noelle, Randolph J.; Gimi, Barjor; Shworak, Nicholas W.; Carriere, Catherine

2012-01-01

41

Downregulation of Connexin 43 promotes vascular cell loss and excess permeability associated with the development of vascular lesions in the diabetic retina  

PubMed Central

Purpose To determine whether downregulation of Connexin 43 (Cx43) expression promotes development of acellular capillaries (ACs), pericyte loss (PL), excess permeability, and retinal thickening in rat retinas. Methods Control rats, diabetic rats, and rats intravitreally injected with Cx43 siRNA or scrambled siRNA were used in this study to determine if acute downregulation of Cx43 expression contributes to retinal vascular cell death and excess permeability. Western blot (WB) analysis and Cx43 immunostaining were performed to assess Cx43 protein levels and distribution in the retinal vessels. Concurrently, retinal networks were subjected to terminal deoxynucleotidyl transferase-mediated uridine 5?-triphosphate-biotin nick end labeling (TUNEL) assay and counter-stained to assess the number of apoptotic cells, ACs, and PL. Assessment of fluorescein isothiocyanate-dextran (FITC-dex) extravasation from retinal capillaries and optical coherence tomography (OCT) were performed to determine retinal vascular permeability and retinal thickness, respectively. Results WB analysis indicated a significant decrease in the Cx43 protein level in the retinas of the diabetic rats and those intravitreally injected with Cx43 siRNA compared to the retinas of the control rats. Likewise, the retinal vascular cells of the diabetic rats and the Cx43 siRNA-treated rats showed a significant decrease in Cx43 immunostaining. Importantly, the number of apoptotic cells, ACs and PL, FITC-dex extravasation, and thickness increased in the retinas of the diabetic and Cx43 siRNA-treated rats compared to those of the control rats. Conclusions Results indicate that downregulation of Cx43 expression alone induces vascular cell death and promotes vascular permeability in the retina. These findings suggest that diabetes-induced downregulation of Cx43 participates in promoting retinal vascular lesions associated with diabetic retinopathy (DR). PMID:24940027

Tien, Thomas; Muto, Tetsuya; Barrette, Kevin; Challyandra, Lucky

2014-01-01

42

Shed GP of Ebola Virus Triggers Immune Activation and Increased Vascular Permeability  

PubMed Central

During Ebola virus (EBOV) infection a significant amount of surface glycoprotein GP is shed from infected cells in a soluble form due to cleavage by cellular metalloprotease TACE. Shed GP and non-structural secreted glycoprotein sGP, both expressed from the same GP gene, have been detected in the blood of human patients and experimentally infected animals. In this study we demonstrate that shed GP could play a particular role during EBOV infection. In effect it binds and activates non-infected dendritic cells and macrophages inducing the secretion of pro- and anti-inflammatory cytokines (TNF?, IL1?, IL6, IL8, IL12p40, and IL1-RA, IL10). Activation of these cells by shed GP correlates with the increase in surface expression of co-stimulatory molecules CD40, CD80, CD83 and CD86. Contrary to shed GP, secreted sGP activates neither DC nor macrophages while it could bind DCs. In this study, we show that shed GP activity is likely mediated through cellular toll-like receptor 4 (TLR4) and is dependent on GP glycosylation. Treatment of cells with anti-TLR4 antibody completely abolishes shed GP-induced activation of cells. We also demonstrate that shed GP activity is negated upon addition of mannose-binding sera lectin MBL, a molecule known to interact with sugar arrays present on the surface of different microorganisms. Furthermore, we highlight the ability of shed GP to affect endothelial cell function both directly and indirectly, demonstrating the interplay between shed GP, systemic cytokine release and increased vascular permeability. In conclusion, shed GP released from virus-infected cells could activate non-infected DCs and macrophages causing the massive release of pro- and anti-inflammatory cytokines and effect vascular permeability. These activities could be at the heart of the excessive and dysregulated inflammatory host reactions to infection and thus contribute to high virus pathogenicity. PMID:25412102

Escudero-Pérez, Beatriz; Volchkova, Valentina A.; Dolnik, Olga; Lawrence, Philip; Volchkov, Viktor E.

2014-01-01

43

Complement and polymorphonuclear leukocytes do not determine the vascular permeability induced by intraocular LPS.  

PubMed

The intravitreous injection of an endotoxin of Escherichia coli 055:B5 (LPS; 0.1-0.5 microgram/50 microliters of saline) induces ocular inflammation in rabbits that is maximal 20-24 hours later and disappears by 4 days. The inflammation is characterized by an alteration in ocular vascular permeability (OVP) measured by the ocular extravasation of 125I-albumin and an outpouring of leukocytes, most of which are polymorphonuclear leukocytes (PMNs), as determined by histopathologic study. Nitrogen mustard (mechlorethamine, 1.75 mg/kg) administered 3 days prior to LPS virtually eliminates PMNs in the circulation and those infiltrating ocular tissues 20 hours after intravitreous LPS, and yet the average increase in vascular permeability is not different from that of controls. Cobra venom factor (CVF; 300-400 units) 7 hours before intravitreous LPS produces a greater than 90% decrease in both hemolytic complement activity and zymosan-inducible serum chemotactic activity; yet 20 hours after LPS, the OVP is the same in CVF-treated rabbits and controls. For comparison, an ocular passive Arthus reaction (ovalbumin-anti-ovalbumin) was significantly affected by CVF pretreatment. Chemotactic activity in the aqueous humor is found in both CVF-treated and control rabbits 20 hours after intravitreous LPS. This activity attracts rabbit, but not human, PMNs, is partially heat-sensitive, and is not inhibited when PMNs are preincubated with C5a. These results indicate that neither PMNs nor circulating complement determine the OVP following intravitreous LPS, and that the chemotactic activity present in aqueous humor at the height of the inflammatory response is not primarily C5a. PMID:3155595

Howes, E L; Wong, K L; Hartiala, K T; Webster, R O; Rosenbaum, J T

1985-01-01

44

Complement and polymorphonuclear leukocytes do not determine the vascular permeability induced by intraocular LPS.  

PubMed Central

The intravitreous injection of an endotoxin of Escherichia coli 055:B5 (LPS; 0.1-0.5 microgram/50 microliters of saline) induces ocular inflammation in rabbits that is maximal 20-24 hours later and disappears by 4 days. The inflammation is characterized by an alteration in ocular vascular permeability (OVP) measured by the ocular extravasation of 125I-albumin and an outpouring of leukocytes, most of which are polymorphonuclear leukocytes (PMNs), as determined by histopathologic study. Nitrogen mustard (mechlorethamine, 1.75 mg/kg) administered 3 days prior to LPS virtually eliminates PMNs in the circulation and those infiltrating ocular tissues 20 hours after intravitreous LPS, and yet the average increase in vascular permeability is not different from that of controls. Cobra venom factor (CVF; 300-400 units) 7 hours before intravitreous LPS produces a greater than 90% decrease in both hemolytic complement activity and zymosan-inducible serum chemotactic activity; yet 20 hours after LPS, the OVP is the same in CVF-treated rabbits and controls. For comparison, an ocular passive Arthus reaction (ovalbumin-anti-ovalbumin) was significantly affected by CVF pretreatment. Chemotactic activity in the aqueous humor is found in both CVF-treated and control rabbits 20 hours after intravitreous LPS. This activity attracts rabbit, but not human, PMNs, is partially heat-sensitive, and is not inhibited when PMNs are preincubated with C5a. These results indicate that neither PMNs nor circulating complement determine the OVP following intravitreous LPS, and that the chemotactic activity present in aqueous humor at the height of the inflammatory response is not primarily C5a. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:3155595

Howes, E. L.; Wong, K. L.; Hartiala, K. T.; Webster, R. O.; Rosenbaum, J. T.

1985-01-01

45

Nlrp3 Prevents Early Renal Interstitial Edema and Vascular Permeability in Unilateral Ureteral Obstruction  

PubMed Central

Progressive renal disease is characterized by tubulo-interstitial injury with ongoing inflammation and fibrosis. The Nlrp3 inflammasome contributes to these pathophysiological processes through its canonical effects in cytokine maturation. Nlrp3 may additionally exert inflammasome-independent effects following tissue injury. Hence, in this study we investigated potential non-canonical effects of Nlrp3 following progressive renal injury by subjecting WT and Nlrp3-deficient (?/?) mice to unilateral ureter obstruction (UUO). Our results revealed a progressive increase of renal Nlrp3 mRNA in WT mice following UUO. The absence of Nlrp3 resulted in enhanced tubular injury and dilatation and an elevated expression of injury biomarker NGAL after UUO. Moreover, interstitial edema was significantly elevated in Nlrp3?/? mice. This could be explained by increased intratubular pressure and an enhanced tubular and vascular permeability. In accordance, renal vascular leakage was elevated in Nlrp3?/? mice that associated with reduced mRNA expression of intercellular junction components. The decreased epithelial barrier function in Nlrp3?/? mice was not associated with increased apoptosis and/or proliferation of renal epithelial cells. Nlrp3 deficiency did not affect renal fibrosis or inflammation. Together, our data reveal a novel non-canonical effect of Nlrp3 in preserving renal integrity and protection against early tubular injury and interstitial edema following progressive renal injury. PMID:24454932

Pulskens, Wilco P.; Butter, Loes M.; Teske, Gwendoline J.; Claessen, Nike; Dessing, Mark C.; Flavell, Richard A.; Sutterwala, Fayyaz S.; Florquin, Sandrine; Leemans, Jaklien C.

2014-01-01

46

Nlrp3 prevents early renal interstitial edema and vascular permeability in unilateral ureteral obstruction.  

PubMed

Progressive renal disease is characterized by tubulo-interstitial injury with ongoing inflammation and fibrosis. The Nlrp3 inflammasome contributes to these pathophysiological processes through its canonical effects in cytokine maturation. Nlrp3 may additionally exert inflammasome-independent effects following tissue injury. Hence, in this study we investigated potential non-canonical effects of Nlrp3 following progressive renal injury by subjecting WT and Nlrp3-deficient (-/-) mice to unilateral ureter obstruction (UUO). Our results revealed a progressive increase of renal Nlrp3 mRNA in WT mice following UUO. The absence of Nlrp3 resulted in enhanced tubular injury and dilatation and an elevated expression of injury biomarker NGAL after UUO. Moreover, interstitial edema was significantly elevated in Nlrp3-/- mice. This could be explained by increased intratubular pressure and an enhanced tubular and vascular permeability. In accordance, renal vascular leakage was elevated in Nlrp3-/- mice that associated with reduced mRNA expression of intercellular junction components. The decreased epithelial barrier function in Nlrp3-/- mice was not associated with increased apoptosis and/or proliferation of renal epithelial cells. Nlrp3 deficiency did not affect renal fibrosis or inflammation. Together, our data reveal a novel non-canonical effect of Nlrp3 in preserving renal integrity and protection against early tubular injury and interstitial edema following progressive renal injury. PMID:24454932

Pulskens, Wilco P; Butter, Loes M; Teske, Gwendoline J; Claessen, Nike; Dessing, Mark C; Flavell, Richard A; Sutterwala, Fayyaz S; Florquin, Sandrine; Leemans, Jaklien C

2014-01-01

47

A 3D porous media liver lobule model: the importance of vascular septa and anisotropic permeability for homogeneous perfusion.  

PubMed

The hepatic blood circulation is complex, particularly at the microcirculatory level. Previously, 2D liver lobule models using porous media and a 3D model using real sinusoidal geometries have been developed. We extended these models to investigate the role of vascular septa (VS) and anisotropic permeability. The lobule was modelled as a hexagonal prism (with or without VS) and the tissue was treated as a porous medium (isotropic or anisotropic permeability). Models were solved using computational fluid dynamics. VS inclusion resulted in more spatially homogeneous perfusion. Anisotropic permeability resulted in a larger axial velocity component than isotropic permeability. A parameter study revealed that results are most sensitive to the lobule size and radial pressure drop. Our model provides insight into hepatic microhaemodynamics, and suggests that inclusion of VS in the model leads to perfusion patterns that are likely to reflect physiological reality. The model has potential for applications to unphysiological and pathological conditions. PMID:23237543

Debbaut, Charlotte; Vierendeels, Jan; Siggers, Jennifer H; Repetto, Rodolfo; Monbaliu, Diethard; Segers, Patrick

2014-01-01

48

Metamaterials with negative permeability and negative refractive index: experiments and simulations  

Microsoft Academic Search

We report the transmission characteristics of split-ring resonator and left-handed metamaterials (LHM) in the microwave frequency regime. A left-handed transmission band is observed at the frequencies where both dielectric permittivity and magnetic permeability are negative. The reflection characteristics of ordered and disordered LHMs are studied. The two-dimensional LHM structure is verified to have a negative refractive index. We employed three

Ekmel Ozbay; Kaan Guven; Koray Aydin

2007-01-01

49

Measurement of injectivity indexes in geothermal wells with two permeable zones  

SciTech Connect

Injectivity tests in wells with two permeable zones and internal flow is analyzed in order to include the usually severe thermal transient effects. A theoretical analysis is performed and a method devised to obtain information from the thermal transient, provided that temperature is measured simultaneously with pressure. The technique is illustrated with two real tests performed at Miravalles, Costa Rica. It allows to estimate total injectivity index as well as the injectivity index of each one of the two zones separately. Correct position of measuring tools and nature of spontaneous internal flow is also discussed.

Acuna, Jorge A.

1994-01-20

50

Permeability  

NSDL National Science Digital Library

This web page describes the permeability of a magnetic material. A magnetization curve with hysteresis demonstrates the relation between magnetic field and magnetic flux. This is part of a large web site on the magnetic properties of materials. This item is part of a larger collection of educational resources developed by the Non-destructive Testing Resource Center.

2010-02-19

51

Permeability  

NSDL National Science Digital Library

This web page describes the permeability of a magnetic material. A magnetization curve with hysteresis demonstrates the relation between magnetic field and magnetic flux. This is part of a large web site on the magnetic properties of materials. This item is part of a larger collection of educational resources developed by the Non-destructive Testing Resource Center.

2007-10-12

52

Dissociation of cutaneous vascular permeability and the development of cutaneous late-phase allergic reactions  

SciTech Connect

Cutaneous late-phase allergic reactions (LPR) are characterized by an early, immediate hypersensitivity whealing reaction followed by persistent, localized induration that peaks 6 to 8 hours later. In this study we used rodents to examine the relationship between vascular permeability (VP) and induration during LPR. Efflux of macromolecular tracers from the vasculature into skin was measured with the use of radiolabeled albumin and neutral dextran tracers having large molecular radii. To induce LPR immunologically, we used either intradermal injections of antirat IgE or passive cutaneous sensitization with IgE antidinitrophenyl followed 24 hours later by intravenous injection of albumin-dinitrophenyl. (/sup 125/I)albumin and (/sup 3/H)dextran tracers were injected intravenously before and at various intervals after the induction of LPR. Although a marked increase in VP occurred within the first 30 minutes after induction of mast cell degranulation, analysis of radiolabeled tracer accumulation at 2, 4, 8, and 24 hours failed to demonstrate any further increase in VP. These findings indicate that the induration observed in rodent LPR is not associated with increased VP beyond the immediate hypersensitivity stage and suggest that impairment of lymphatic drainage, cellular infiltration, and/or fibrin deposition are contributing factors.

Keahey, T.M.; Indrisano, J.; Kaliner, M.A.

1989-03-01

53

Increased vascular permeability of solid tumors causes selectivity of 5-aminolevulinic acid (ALA) induced porphyrins  

NASA Astrophysics Data System (ADS)

To investigate pharmacokinetics of ALA-induced porphyrins the time course of fluorescence in neoplastic tissue and normal tissue following i.v. administration of ALA (100 mg kg-1, 500 mg kg-1 or 1000 mg kg-1 b.w.) was studied by means of intravital fluorescence microscopy. As a model the amelanotic melanoma (A-Mel- 3) growing in a transparent skin fold chamber preparation was used (n equals 18). Maximal fluorescence intensity was measured after 2.5 h in tumor and after 6 h in surrounding host tissue, highest tumor/host tissue ratio at 90 min (500 mg kg-1 b.w.). Heterogeneity of fluorescence intensity between different tumors ranged from 24% to 361% following injection of 500 mg/kg b.w. Twenty-four hours after systemic administration of ALA fluorescence intensity was decreased to baseline. Based upon these results a three- compartment model was calculated to simulate fluorescence kinetics in solid, well vascularized tumors assuming first-order kinetics. This compartment model supports the experimental findings, that the transient selectivity of ALA-induced fluorescence in tumors is caused by earlier uptake of ALA in tumors due to increased microvascular permeability and diffusion in neoplastic tissue. The heterogeneity might represent the different metabolic capacity of tumors to form porphyrins following exogenous administration of ALA.

Abels, Christoph; Heil, Peter; Dellian, Marc; Kuhnle, Gerhard E.; Baumgartner, Reinhold; Goetz, Alwin E.

1995-03-01

54

Increased vascular permeability of solid tumors causes selectivity of 5-aminolevulinic acid (ALA) induced porphyrins  

NASA Astrophysics Data System (ADS)

To investigate pharmacokinetics of ALA-induced porphyrins the time course of fluorescence in neoplastic tissue and normal tissue following i.v. administration of ALA (100 mg kg-1, 500 mg kg-1 or 1000 mg kg-1 b.w.) was studied by means of intravital fluorescence microscopy. As a model the amelanotic melanoma (A-Mel- 3) growing in a transparent skin fold chamber preparation was used (n equals 18). Maximal fluorescence intensity was measured after 2.5 h in tumor and after 6 h in surrounding host tissue, highest tumor/host tissue ratio at 90 min (500 mg kg-1 b.w.). Heterogeneity of fluorescence intensity between different tumors ranged from 24% to 361% following injection of 500 mg/kg b.w. Twenty-four hours after systemic administration of ALA fluorescence intensity was decreased to baseline. Based upon these results a three- compartment model was calculated to simulate fluorescence kinetics in solid, well vascularized tumors assuming first-order kinetics. This compartment model supports the experimental findings, that the transient selectivity of ALA-induced fluorescence in tumors is caused by earlier uptake of ALA in tumors due to increased microvascular permeability and diffusion in neoplastic tissue. The heterogeneity might represent the different metabolic capacity of tumors to form porphyrins following exogenous administration of ALA.

Abels, Christoph; Heil, Peter; Dellian, Marc; Kuhnle, Gerhard E.; Baumgartner, Reinhold; Goetz, Alwin E.

1994-10-01

55

Prazosin treatment suppresses increased vascular permeability in both acute and passively transferred experimental autoimmune encephalomyelitis in the lewis rat  

SciTech Connect

Prazosin, an antagonist of the ..cap alpha../sub 1/-adrenoceptor, has been found to suppress the clinical and histologic expression of experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. This effect appears to be specific for the ..cap alpha../sub 1/-receptor. To determine the effect of this drug on vascular permeability to serum proteins and inflammatory cells, leakage of serum proteins into the central nervous system (CNS) was measured with (/sup 125/I)albumin, and quantitation of cellular inflammation was determined by an estimation of total DNA. The results show that in both actively induced and passively transferred models of the disease, treatment with prazosin significantly suppresses leakage of serum proteins into the CNS but does not significantly suppress the increase of DNA. The results of the (/sup 125/I)albumin studies additionally support the conclusion that the extent of vascular permeability to serum proteins in the spinal cord is a significant correlate of clinical disease. The results of the DNA estimation were at variance with the histologic evidence of cellular infiltration. The authors conclude that treatment with prazosin has a significant effect on the development of vascular edema in EAE. These results additionally validate a role for the adrenergic receptor in the development of EAE, and support the hypothesis that the primary site of action of prazosin is on the vascular ..cap alpha../sub 1/-adrenoceptor.

Goldmuntz, E.A.; Brosnan, C.F.; Norton, W.T.

1986-12-01

56

Bactericidal/permeability-increasing protein protects vascular endothelial cells from lipopolysaccharide-induced activation and injury.  

PubMed Central

Bactericidal/permeability-increasing protein (BPI), a human neutrophil granule protein, has been shown to bind lipopolysaccharide (LPS) and neutralize LPS-mediated cytokine production in adherent monocytes and the whole-blood system. In this study we investigated the ability of recombinant human BPI (rBPI) to inhibit LPS-induced vascular endothelial cell (EC) injury and activation. rBPI inhibited significantly both rough and smooth LPS-mediated injury for cultured bovine brain microvessel ECs, as measured by lactic dehydrogenase release, and blocked the LPS-induced interleukin-6 (IL-6) release from human umbilical vein ECs in a dose-dependent manner. BPI was able to inhibit LPS-mediated EC injury or activation whether it was added before or at the same time with LPS, but delaying the time of addition of rBPI resulted only in a partial inhibition. BPI also inhibited LPS-induced tumor necrosis factor alpha, IL-1 beta, and IL-6 release from human whole blood. This inhibition of tumor necrosis factor alpha, IL-1 beta, and IL-6 release from whole blood was maximal when BPI was premixed with LPS before addition to blood and was partial when BPI was added simultaneously with LPS, but no inhibition was observed when the addition of rBPI was delayed for 5 min. These findings suggest that rBPI is a potent inhibitor of LPS-mediated responses in ECs and whole blood and underscore the potential use of BPI in treatment or prevention of endotoxic shock. In contrast, the anti-lipid A monoclonal antibodies HA-1A and E5 were ineffective in inhibiting LPS-mediated EC injury and activation as well as LPS-induced cytokine release in whole blood. PMID:8063410

Arditi, M; Zhou, J; Huang, S H; Luckett, P M; Marra, M N; Kim, K S

1994-01-01

57

Disintegrin Metalloprotease (ADAM) 10 Regulates Endothelial Permeability and T Cell Transmigration by Proteolysis of Vascular Endothelial Cadherin  

PubMed Central

Vascular endothelial (VE)-cadherin is the major adhesion molecule of endothelial adherens junctions. It plays an essential role in controlling endothelial permeability, vascular integrity, leukocyte transmigration, and angiogenesis. Elevated levels of soluble VE-cadherin are associated with diseases like coronary atherosclerosis. Previous data showed that the extracellular domain of VE-cadherin is released by an unknown metalloprotease activity during apoptosis. In this study, we used gain of function analyses, inhibitor studies and RNA interference experiments to analyze the proteolytic release of VE-cadherin in human umbilical vein endothelial cells (HUVECs). We found that VE-cadherin is specifically cleaved by the disintegrin and metalloprotease ADAM10 in its ectodomain releasing a soluble fragment and generating a carboxyterminal membrane bound stub, which is a substrate for a subsequent ?-secretase cleavage. This ADAM10-mediated proteolysis could be induced by Ca2+-influx and staurosporine treatment, indicating that ADAM10-mediated VE-cadherin cleavage contributes to the dissolution of adherens junctions during endothelial cell activation and apoptosis, respectively. In contrast, protein kinase C activation or inhibition did not modulate VE-cadherin processing. Increased ADAM10 expression was functionally associated with an increase in endothelial permeability. Remarkably, our data indicate that ADAM10 activity also contributes to the thrombin-induced decrease of endothelial cell-cell adhesion. Moreover, knockdown of ADAM10 in HUVECs as well as in T cells by small interfering RNA impaired T cell transmigration. Taken together our data identify ADAM10 as a novel regulator of vascular permeability and demonstrate a hitherto unknown function of ADAM10 in the regulation of VE-cadherin-dependent endothelial cell functions and leukocyte transendothelial migration. PMID:18420943

Schulz, Beate; Pruessmeyer, Jessica; Maretzky, Thorsten; Ludwig, Andreas; Blobel, Carl P.; Saftig, Paul; Reiss, Karina

2009-01-01

58

Stimulation of endothelial cell migration by vascular permeability factor/vascular endothelial growth factor through cooperative mechanisms involving the alphavbeta3 integrin, osteopontin, and thrombin.  

PubMed Central

We have identified several mechanisms by which the angiogenic cytokine vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) likely regulates endothelial cells (EC) migration. VPF/VEGF induced dermal microvascular EC expression of mRNAs encoding the alphav and beta3 integrin subunits resulting in increased levels of the alphavbeta3 heterodimer at the cell surface, and VPF/VEGF also induced mRNA encoding osteopontin (OPN), an alphavbeta3 ligand. OPN promoted EC migration in vitro; and VPF/VEGF induction of alphavbeta3 was accompanied by increased EC migration toward OPN. Because thrombin cleavage of OPN results in substantial enhancement of OPN's adhesive properties, and because VPF/VEGF promotes increased microvascular permeability leading to activation of the extrinsic coagulation pathway, we also investigated whether VPF/VEGF facilitates thrombin cleavage of OPN in vivo. Consistent with this hypothesis, co-injection of VPF/VEGF together with OPN resulted in rapid cleavage of OPN by endogenous thrombin. Furthermore, in comparison with native OPN, thrombin-cleaved OPN stimulated a greater rate of EC migration in vitro, which was additive to the increased migration associated with induction of alpha v beta 3. Thus, these data demonstrate cooperative mechanisms for VPF/VEGF regulation of EC migration involving the alphavbeta3 integrin, the alphavbeta3 ligand OPN, and thrombin cleavage of OPN. These findings also illustrate an operational link between VPF/VEGF induction of EC gene expression and VPF/VEGF enhancement of microvascular permeability, suggesting that these distinct biological activities may act accordingly to stimulate EC migration during angiogenesis. Images Figure 1 Figure 2 Figure 4 PMID:8686754

Senger, D. R.; Ledbetter, S. R.; Claffey, K. P.; Papadopoulos-Sergiou, A.; Peruzzi, C. A.; Detmar, M.

1996-01-01

59

Pocket Doppler and vascular laboratory equipment yield comparable results for ankle brachial index measurement  

Microsoft Academic Search

BACKGROUND: The ankle brachial index (ABI) is a well-established tool for screening and diagnosis of peripheral arterial disease (PAD). In this study we assessed the validity of ABI determination using a pocket Doppler device compared with automatic vascular laboratory measurement in patients suspected of PAD. METHODS: Consecutive patients with symptoms of PAD referred for ABI measurement between December 2006 and

Saskia PA Nicolaï; Lotte M Kruidenier; Ellen V Rouwet; Liliane Wetzels-Gulpers; Constantijn AM Rozeman; Martin H Prins; Joep AW Teijink

2008-01-01

60

Duration of action of topical antiallergy drugs in a Guinea pig model of histamine-induced conjunctival vascular permeability.  

PubMed

The topical application of 0.1% olopatadine has been shown to provide significant attenuation of histamine-induced conjunctival vascular permeability (CVP) within 5 min and for as long as 24 h following a topical administration. The duration of the action of olopatadine was compared to that of epinastine, azelastine, and ketotifen. Male Hartley outbred guinea pigs (weighing 250-300 g) were administered a drug or vehicle as single O.D. topical drops, at times ranging from 4 to 24 h prior to histamine challenge. One (1) h prior to histamine challenge, the animals were administered 1 mL of Evans blue dye (1 mg/mL) through the marginal ear vein. Histamine (300 ng) was administered by a subconjunctival injection, and the guinea pigs were sacrificed 30 min later. CVP was assessed as the area and color intensity stained with Evans blue dye. The potencies of each drug were determined by calculating a 50% effective dose (ED(50)) for the inhibition of vascular leakage, compared to vehicle treatment, at each time point. Olopatadine was the only compound tested that was significantly effective 16 h following a single topical application. The ED(50) for olopatadine at 16 h was 0.031%. Epinastine, azelastine, and ketotifen were only significantly effective for up to 4 h. Olopatadine exhibited the longest duration of action for inhibition of histamine-induced vascular permeability in guinea pigs of any topical antiallergic drug tested. Concentrations of olopatadine, which provided a greater than 50% inhibition of the histamine-induced vascular response, were consistently less than 0.1% over a 16-h pretreatment interval. PMID:17803429

Beauregard, Clay; Stephens, Donna; Roberts, Leighann; Gamache, Daniel; Yanni, John

2007-08-01

61

Mitnitski et al. June 17, 2005 A VASCULAR RISK FACTOR INDEX IN RELATION TO MORTALITY AND INCIDENT DEMENTIA  

E-print Network

factor indexes can give robust estimates of dementia and life span prognoses in elderly people, but death DEMENTIA A. Mitnitski a,b , I. Skoog.c , X. Song a , M. Waern c , S. Ã?stlingc , V. Sundh c , B. Steen c: Vascular risk indexes in relation to death and dementia Key words: vascular factors, dementia, mortality

Mitnitski, Arnold B.

62

Blockade of PDE4B limits lung vascular permeability and lung inflammation in LPS-induced acute lung injury.  

PubMed

Acute lung injury (ALI), acute respiratory distress syndrome (ARDS), is actually involved in an ongoing and uncontrolled inflammatory response in lung tissues. Although extensive studies suggested that phospodiesterase type 4B (PDE4B) may be related to inflammation, the underlying cell biological mechanism of ALI remains unclear. To further investigate the mechanism how PDE4B take part in inflammatory response and the maintenance of vascular integrity, we established the experimental model of ALI in vitro and in vivo. In vitro, we found that Cilomilast, Diazepam and PDE4B knockout could potently inhibit the LPS-induced NF-?B activation and inflammatory response in multiple cell types, including lung epithelial cells (A549), pulmonary microvascular endothelial cells (PMVECs) and vascular smooth muscle cells (VSMCs). Besides, PDE4B deletion attenuated the LPS-induced ROS generation. In vivo, PDE4B deletion could attenuate the lung water content, histological signs of pulmonary injury and elevate the ratio of partial pressure of arterial O2 to fraction of inspired O2 (PaO2/FIO2 ratio). Additionally, PDE4B deletion reduced LPS-induced vascular permeability. Collectively, our results strongly indicates that PDE4B is a valid target for anti-ALI. PMID:25019986

Ma, Hongyan; Shi, Jinghui; Wang, Changsong; Guo, Lei; Gong, Yulei; Li, Jie; Gong, Yongtai; Yun, Fengxiang; Zhao, Hongwei; Li, Enyou

2014-08-01

63

Impact of myocardial contrast echocardiography on vascular permeability: comparison of three different contrast agents  

Microsoft Academic Search

Microvascular permeabilization, petechial hemorrhage and premature ventricular contractions (PVCs) have been demonstrated in an in vivo rat model of myocardial contrast echocardiography (MCE). The purpose of this study was to compare these effects for three US Food and Drug Administration (FDA)-approved ultrasound (US) contrast agents (US CA): Optison®, Definity® and Imagent®. Evans blue dye, an indicator of microvascular permeability, and

Peng Li; William F. Armstrong; Douglas L. Miller

2004-01-01

64

Vascular permeability and hyperpermeability in a murine adenocarcinoma after fractionated radiotherapy: an ultrastructural tracer study  

Microsoft Academic Search

Large radiation doses cause postradiation vascular hyperpermeability by disrupting endothelia. The cumulative sequences of small doses (fractionated radiotherapy) standard in clinical practice cause it too, but not by endothelial disruption: the mechanisms are unknown. In this study, correlated fluorescent and ultrastructural localisation of a tracer revealed the architecture, fine structure and function of microvessels in mouse AT17 tumours, before and

Paul L. Debbage; Sonja Seidl; Alfons Kreczy; Peter Hutzler; Margit Pavelka; Peter Lukas

2000-01-01

65

Characterization of Vascular Disruption and Blood-Spinal Cord Barrier Permeability following Traumatic Spinal Cord Injury  

PubMed Central

Abstract Significant vascular changes occur subsequent to spinal cord injury (SCI), which contribute to progressive pathophysiology. In the present study, we used female Wistar rats (300–350?g) and a 35-g clip-compression injury at T6 to T7 to characterize the spatial and temporal vascular changes that ensue post-SCI. Before sacrifice, animals were injected with vascular tracing dyes (2% Evans Blue (EB) or fluorescein isothiocyanate/Lycopersicon esculentum agglutinin [FITC-LEA]) to assess blood–spinal cord barrier (BSCB) integrity or vascular architecture, respectively. Spectrophotometry of EB tissue showed maximal BSCB disruption at 24?h postinjury, with significant disruption observed until 5 days postinjury (p<0.01). FITC-LEA-identified functional vasculature was dramatically reduced by 24?h. Similarly, RECA-1 immunohistochemistry showed a significant decrease in the number of vessels at 24?h postinjury, compared to uninjured animals (p<0.01), with slight increases in endogenous revascularization by 10 days postinjury. White versus gray matter (GM) quantification showed that GM vessels are more susceptible to SCI. Finally, we observed an endogenous angiogenic response between 3 and 7 days postinjury: maximal endothelial cell proliferation was observed at day 5. These data indicate that BSCB disruption and endogenous revascularization occur at specific time points after injury, which may be important for developing effective therapeutic interventions for SCI. PMID:24237182

Figley, Sarah A.; Khosravi, Ramak; Legasto, Jean M.; Tseng, Yun-Fan

2014-01-01

66

Bluetongue Virus and Double-Stranded RNA Increase Human Vascular Permeability: Role of p38 MAPK  

Microsoft Academic Search

Endothelial cell (EC) involvement in viral hemorrhagic fevers has been clearly established. However, virally activated mechanisms leading to endothelial activation and dysfunction are not well understood. Several different potential mechanisms such as direct viral infection, alterations in procoagulant\\/anticoagulant balance, and increased cytokine production have been suggested. We utilized a model of EC barrier dysfunction and vascular endothelial leakage to explore

EDDIE T. CHIANG; DIXIE-ANN PERSAUD-SAWIN; SANDHYA KULKARNI; JOE G. N. GARCIA; FARHAD IMANI

2006-01-01

67

Regulators of vascular permeability: potential sites for intervention in the treatment of macular edema  

Microsoft Academic Search

Rather than being a non-specific reaction to a noxious stimulus, breakdown of the capillary blood-retinal barrier causing\\u000a macular edema appears to be dependent on a number of active processes which may be open to pharmacological manipulation. Extracellular\\u000a influences which may affect barrier function include serum and neighboring cell types, which act though cytokines, such as\\u000a vascular endothelial growth factor and

Mark C. Gillies

1999-01-01

68

Aminoguanidine effects on nerve blood flow, vascular permeability, electrophysiology, and oxygen free radicals  

SciTech Connect

Since advanced glycosylation end products have been suggested to mediate hyperglycemia-induced microvascular atherogenesis and because aminoguanidine (AG) prevents their generation, the authors examined whether AG could prevent or ameliorate the physiologic and biochemical indices of streptozotocin (STZ)-induced experimental diabetic neuropathy. Four groups of adult Sprague-Dawley rats were studied: group I received STZ plus AG, group II received STZ plus AG, group III received STZ alone, and group IV was a control. They monitored conduction and action potential amplitudes serially in sciatic-tibial and caudal nerves, nerve blood flow, oxygen free radical activity (conjugated dienes and hydroperoxides), and the product of the permeability coefficient and surface area to {sup 125}I-labeled albumin. STZ-induced diabetes (group III) caused a 57% reduction in nerve blood flow and in abnormal nerve conduction and amplitudes and a 60% increase in conjugated dienes. Nerve blood flow was normalized by 8 weeks with AG (groups I and II) and conduction was significantly improved, in a dose-dependent manner, by 16 and 24 weeks in sciatic-tibial and caudal nerves, respectively. The permeability coefficient was not impaired, suggesting a normal blood-nerve barrier function for albumin, and the oxygen free-radical indices were not ameliorated by AG. They suggest that AG reverses nerve ischemia and more gradually improves their electrophysiology by an action on nerve microvessels. AG may have potential in the treatment of diabetic neuropathy.

Kihara, Mikihiro; Schmelzer, J.D.; Poduslo, J.F.; Curran, G.L.; Nickander, K.K.; Low, P.A. (Mayo Foundation, Rochester, MN (United States))

1991-07-15

69

Epigalloccatechin-3-gallate inhibits ocular neovascularization and vascular permeability in human retinal pigment epithelial and human retinal microvascular endothelial cells via suppression of MMP-9 and VEGF activation.  

PubMed

Epigalloccatechin-3-gallate (EGCG) is the main polyphenol component of green tea (leaves of Camellia sinensis). EGCG is known for its antioxidant, anti-inflammatory, antiviral, and anti-carcinogenic properties. Here, we identify EGCG as a new inhibitor of ocular angiogenesis and its vascular permeability. Matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) play a key role in the processes of extracellular matrix (ECM) remodeling and microvascular permeability during angiogenesis. We investigated the inhibitory effects of EGCG on ocular neovascularization and vascular permeability using the retina oriented cells and animal models induced by VEGF and alkaline burn. EGCG treatment significantly decreased mRNA and protein expression levels of MMP-9 in the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA) and tumor necrosis factor alpha (TNF-?) in human retinal pigment epithelial cells (HRPECs). EGCG also effectively protected ARPE-19 cells from cell death and attenuated mRNA expressions of key angiogenic factors (MMP-9, VEGF, VEGF Receptor-2) by inhibiting generation of reactive oxygen species (ROS). EGCG significantly inhibited proliferation, vascular permeability, and tube formation in VEGF-induced human retinal microvascular endothelial cells (HRMECs). Furthermore, EGCG significantly reduced vascular leakage and permeability by blood-retinal barrier breakdown in VEGF-induced animal models. In addition, EGCG effectively limited upregulation of MMP-9 and platelet endothelial cell adhesion molecule (PECAM/CD31) on corneal neovascularization (CNV) induced by alkaline burn. Our data suggest that MMP-9 and VEGF are key therapeutic targets of EGCG for treatment and prevention of ocular angiogenic diseases such as age-related macular degeneration, diabetic retinopathy, and corneal neovascularization. PMID:25123184

Lee, Hak Sung; Jun, Jae-Hyun; Jung, Eun-Ha; Koo, Bon Am; Kim, Yeong Shik

2014-01-01

70

Impact of Enzymatic Degradation of the Endothelial Glycocalyx on Vascular Permeability in an Awake Hamster Model  

PubMed Central

Background. The inside of the endothelium is covered by a glycocalyx layer, and enzymatic degradation of this layer induces vascular leakage ex vivo. We hypothesized that enzymatic degrading of the glycocalyx in an in vivo, whole body model, would induce plasma leakage and affect the microcirculation. Methods. Golden Syrian hamsters were divided into an enzyme (hyaluronidase) and a control group. Mean arterial pressure (MAP), heart rate (HR), hematocrit (Hct), base excess (BE), and plasma volume were obtained before, 45 and 120?min after enzyme/saline treatment. Plasma volume was evaluated by the distribution volume of indocyanine green and the microcirculation by functional capillary density (FCD). The enzymatic effect was determined by measuring plasma levels of hyaluronan (HA). Results. There were no differences in MAP, HR, Hct, and BE between the two groups. Enzyme treatment did not induce changes in plasma volume but reduced FCD. There was a 50–100-fold increase in plasma HA, but no relationship was found between HA levels and plasma volume or FCD. Conclusion. Vascular leakage was not confirmed in an in vivo, whole body model after degradation of the endothelial glycocalyx. The microcirculation was affected, but no relationship between plasma levels of HA and FCD was seen. PMID:22792450

Landsverk, S. A.; Tsai, A. G.; Cabrales, P.; Intaglietta, M.

2012-01-01

71

Cardio-ankle vascular index (CAVI) as an indicator of arterial stiffness  

PubMed Central

Arterial stiffness has been identified as an independent predictor of prognostic outcomes for patients with cardiovascular disease. Although measurement of pulse wave velocity has been a widely accepted noninvasive approach to the assessment of arterial stiffness, its accuracy is hampered by changes in blood pressure. Taking the exponential relation between intravascular pressure and arterial diameter into consideration, a stiffness parameter can be obtained by plotting the natural logarithm of systolic–diastolic pressure ratio against the arterial wall extensibility. Cardio-ankle vascular index (CAVI), which is calculated based on the stiffness parameter thus obtained, is theoretically independent of changes in blood pressure. With this distinct advantage, CAVI has been widely applied clinically to assess arterial stiffness in subjects with known cardiovascular diseases including those with diagnosed atherosclerosis, coronary heart disease, and stroke as well as those at risk, including those with hypertension, diabetes, the elderly, and the obese. Because of its enhanced sensitivity, not only has the index been used to discern subtle changes in the disease process, it has also been utilized in studying normal individuals to assess their potential risks of developing cardiovascular diseases. The primary aims of assessing arterial stiffness using CAVI are not only to aid in early detection of arteriosclerosis to allow timely treatment and change in lifestyle, but also to quantitatively evaluate the progression of disease and the effectiveness of treatment. Despite its merit of being unaffected by blood pressure, discretion in data interpretation is suggested because an elevated CAVI represents not just vascular stiffness caused by pathological changes in the arterial wall, but can also be attributed to an increased vascular tone brought about by smooth muscle contraction. Moreover, certain patient populations, such as those with an ankle-brachial index < 0.9, may give falsely low CAVI and are suggested to be excluded from study. PMID:23667317

Sun, Cheuk-Kwan

2013-01-01

72

Segmental differentiation of permeability, protein glycosylation, and morphology of cultured bovine lung vascular endothelium.  

PubMed

The barrier function, surface biochemistry, and morphology of confluent monolayers of endothelial cells isolated from different segments of the bovine lung vasculature [microvessels (BLMVEC), vein (BPVEC) and artery (BPAEC)] were grown in culture and compared. A number of common cell surface proteins were identified along with two proteins of 46 and 48 kDa found exclusively on BPVEC. Lectin affinity chromatography revealed multiple glycosylation differences. The lectins, Arachis hypogaea (AHA) and Lycopersicum esculentum (LEA) agglutinins, interacted with several glycoproteins of BLMVEC but not of BPAEC. Bandeiraea simplicifolia (BS-1) and Caragana arborescens (CAA) agglutinins recognized several glycoproteins of BPVEC and BPAEC but not BLMVEC. Permeabilities were much lower for BLMVEC than BPAEC or BPVEC monolayers, with a range of about 16-fold less for sucrose to 2-fold less for albumin. Electron microscopy revealed that BLMVEC have a greater surface density of plasmalemmal vesicles (approximately 4-fold) and more extensively developed intercellular junctions with more focal membrane adhesion sites per junction (approximately 9-fold) than the other cells. We conclude that: i) BLMVEC monolayers form a much more restrictive barrier to molecular transport as a result of the tighter junctional formation; and ii) endothelial surface glycoproteins may be differentially glycosylated depending on their segmental location within the vasculature. PMID:8123001

Schnitzer, J E; Siflinger-Birnboim, A; Del Vecchio, P J; Malik, A B

1994-02-28

73

Measurement of canine gastric vascular permeability to plasma proteins in the normal and protein-losing states  

SciTech Connect

An isolated segment of the greater curvature of a dog's stomach was perfused at constant flow through a single cannulated artery with donor blood containing 131I-albumin, 125I-fibrinogen, and papaverine. Perfusion pressure was 30-50 mmHg, and venous pressure was set at 15 mmHg. Venous blood was collected in 1-min samples for 60 min. Filtration of fluid and loss of labeled proteins were calculated as the difference between measured arterial inflow and venous outflow. Permeability-surface area products (PS) were calculated for the proteins, and reflection coefficients (sigma) were calculated from solute flux and filtration. Intraarterial infusion of histamine (1.6-1.9 microgram . ml-1) increased filtration and PS and decreased sigma for albumin but not fibrinogen. When protein-losing was established by topical irrigation with 10 mM dithiothreitol in neutral solution, filtration and PS increased, and sigma for albumin but not fibrinogen decreased. Irrigation of the mucosa with 10 mM salicylic acid in 100 mN HCl caused bleeding that was quantitated by addition of 51Cr-erythrocytes to perfusing blood. Filtration and PS increased, and sigma for albumin but not fibrinogen decreased. Hematocrit of blood lost remained low during extensive mucosal damage. Effects of histamine infusion were attenuated or abolished by cimetidine (4 mg . kg-1 loading, 1.4 mg . kg-1 . h-1 continuous infusion) or by pyrilamine maleate (5 mg . kg-1 bolus injection at beginning of irrigation, repeated at 40-50 min). Pyrilamine attenuated or abolished effects of topical dithiothreitol or salicylic acid. We conclude that during protein loss caused by dithiothreitol or salicylic acid, histamine released within the mucosa causes increased vascular permeability for plasma proteins.

Wood, J.G.; Davenport, H.W.

1982-04-01

74

PTEN deficiency in mast cells causes a mastocytosis-like proliferative disease that heightens allergic responses and vascular permeability.  

PubMed

Kit regulation of mast cell proliferation and differentiation has been intimately linked to the activation of phosphatidylinositol 3-OH kinase (PI3K). The activating D816V mutation of Kit, seen in the majority of mastocytosis patients, causes a robust activation of PI3K signals. However, whether increased PI3K signaling in mast cells is a key element for their in vivo hyperplasia remains unknown. Here we report that dysregulation of PI3K signaling in mice by deletion of the phosphatase and tensin homolog (Pten) gene (which regulates the levels of the PI3K product, phosphatidylinositol 3,4,5-trisphosphate) caused mast cell hyperplasia and increased numbers in various organs. Selective deletion of Pten in the mast cell compartment revealed that the hyperplasia was intrinsic to the mast cell. Enhanced STAT5 phosphorylation and increased expression of survival factors, such as Bcl-XL, were observed in PTEN-deficient mast cells, and these were further enhanced by stem cell factor stimulation. Mice carrying PTEN-deficient mast cells also showed increased hypersensitivity as well as increased vascular permeability. Thus, Pten deletion in the mast cell compartment results in a mast cell proliferative phenotype in mice, demonstrating that dysregulation of PI3K signals is vital to the observed mast cell hyperplasia. PMID:21926349

Furumoto, Yasuko; Charles, Nicolas; Olivera, Ana; Leung, Wai Hang; Dillahunt, Sandra; Sargent, Jennifer L; Tinsley, Kevin; Odom, Sandra; Scott, Eric; Wilson, Todd M; Ghoreschi, Kamran; Kneilling, Manfred; Chen, Mei; Lee, David M; Bolland, Silvia; Rivera, Juan

2011-11-17

75

Up-Regulation of Pressure-activated Ca2+-permeable Cation Channel in Intact Vascular Endothelium of Hypertensive Rats  

NASA Astrophysics Data System (ADS)

In endothelial cells, stretch-activated cation channels have been proposed to act as mechanosensors for changes in hemodynamic forces. We have identified a novel mechanosensitive pressure-activated channel in intact endothelium from rat aorta and mesenteric artery. The 18-pS cation channel responded with a multifold increase in channel activity when positive pressure was applied to the luminal cell surface with the patch pipette and inactivated at negative pipette pressure. Channel permeability ratio for K+, Na+, and Ca2+ ions was 1:0.98:0.23. Ca2+ influx through the channel was sufficient to activate a neighboring Ca2+-dependent K+ channel. Hemodynamic forces are chronically disturbed in arterial hypertension. Endothelial cell dysfunction has been implicated in the pathogenesis of arterial hypertension. In two comparative studies, density of the pressure-activated channel was found to be significantly higher in spontaneously hypertensive rats and renovascular hypertensive rats compared with their respective normotensive controls. Channel activity presumably leads to mechanosensitive Ca2+ influx and induces cell hyperpolarization by K+ channel activity. Both Ca2+ influx and hyperpolarization are known to induce a vasodilatory endothelial response by stimulating endothelial nitric oxide (NO) production. Up-regulation of channel density in hypertension could, therefore, represent a counterregulatory mechanism of vascular endothelium.

Hoyer, J.; Kohler, R.; Haase, W.; Distler, A.

1996-10-01

76

Upregulation of Tissue Factor by Activated Stat3 Contributes to Malignant Pleural Effusion Generation via Enhancing Tumor Metastasis and Vascular Permeability in Lung Adenocarcinoma  

PubMed Central

Malignant pleural effusion (MPE) is a poor prognostic sign for patients with lung cancer. Tissue factor (TF) is a coagulation factor that participates in angiogenesis and vascular permeability and is abundant in MPE. We previously demonstrated that autocrine IL-6-activated Stat3 contributes to tumor metastasis and upregulation of VEGF, resulting in the generation of MPE in lung adenocarcinoma. In this study, we found IL-6-triggered Stat3 activation also induces TF expression. By using pharmacologic inhibitors, it was shown that JAK2 kinase, but not Src kinase, contributed to autocrine IL-6-induced TF expression. Inhibition of Stat3 activation by dominant negative Stat3 (S3D) in lung adenocarcinoma suppressed TF-induced coagulation, anchorage-independent growth in vitro, and tumor growth in vivo. Consistently, knockdown of TF expression by siRNA resulted in a reduction of anchorage-independent growth of lung adenocarcinoma cells. Inhibition of TF expression also decreased the adhesion ability of cancer cells in normal lung tissues. In the nude mouse model, both lung metastasis and MPE generation were decreased when PC14PE6/AS2-siTF cells (TF expression was silenced) were intravenously injected. PC14PE6/AS2-siTF cells also produced less malignant ascites through inhibition of vascular permeability. In summary, we showed that TF expression plays a pivotal role in the pathogenesis of MPE generation via regulating of tumor metastasis and vascular permeability in lung adenocarcinoma bearing activated Stat3. PMID:24086497

Yeh, Hsuan-Heng; Chang, Wen-Tsan; Lu, Kuang-Chu; Lai, Wu-Wei; Liu, Hsiao-Sheng; Su, Wu-Chou

2013-01-01

77

Vascular permeability in cancer and infection as related to macromolecular drug delivery, with emphasis on the EPR effect for tumor-selective drug targeting  

PubMed Central

Tumor and inflammation have many common features. One hallmark of both is enhanced vascular permeability, which is mediated by various factors including bradykinin, nitric oxide (NO), peroxynitrite, prostaglandins etc. A unique characteristic of tumors, however, is defective vascular anatomy. The enhanced vascular permeability in tumors is also distinctive in that extravasated macromolecules are not readily cleared. We utilized the enhanced permeability and retention (EPR) effect of tumors for tumor selective delivery of macromolecular drugs. Consequently, such drugs, nanoparticles or lipid particles, when injected intravenously, selectively accumulate in tumor tissues and remain there for long periods. The EPR effect of tumor tissue is frequently inhomogeneous and the heterogeneity of the EPR effect may reduce the tumor delivery of macromolecular drugs. Therefore, we developed methods to augment the EPR effect without inducing adverse effects for instance raising the systemic blood pressure by infusing angiotensin II during arterial injection of SMANCS/Lipiodol. This method was validated in clinical setting. Further, benefits of utilization of NO-releasing agent such as nitroglycerin or angiotensin-converting enzyme (ACE) inhibitors were demonstrated. The EPR effect is thus now widely accepted as the most basic mechanism for tumor-selective targeting of macromolecular drugs, or so-called nanomedicine. PMID:22450535

MAEDA, Hiroshi

2012-01-01

78

New noninvasive index for evaluation of the vascular age of healthy and sick people  

NASA Astrophysics Data System (ADS)

We conducted a study on 861 healthy and sick subjects and demonstrated that some calculated parameters based on measurement of the dynamic light scattering (DLS) signal from the finger correlate highly with chronological age ranging from 1.5 to 85 years old. Measurements of DLS signals were obtained during both occlusion and nonocclusion of blood flow in the finger. For the nonocclusion case we found that the low-frequency component of the DLS signal significantly correlates with the biological age while the high-frequency component of the DLS signal resembles the arterial pulse-wave and does correlate with age. However, the most prominent correlation between the DLS characteristics and age was noted with the stasis stage measurements. We propose that the observed age-related phenomena are caused by alterations in local blood viscosity and interactions of the endothelial cells with erythrocytes. Further, a new noninvasive index based on the age-related optical characteristics was introduced. This noninvasive index may be used as a research and diagnostic tool to examine the endothelial and thrombolytic properties of the vascular system.

Fine, Ilya; Kuznik, Boris I.; Kaminsky, Alexander V.; Shenkman, Louis; Kustovsjya, Evgeniya M.; Maximova, Olga G.

2012-08-01

79

Compact-2D FDTD for waveguides including materials with negative dielectric permittivity, magnetic permeability and refractive index  

NASA Astrophysics Data System (ADS)

An efficient compact-2D finite-difference time-domain method is presented for the numerical analysis of guided modes in waveguides that may include negative dielectric permittivity, negative magnetic permeability and negative refractive index materials. Both complex variable and real variable methods are given. The method is demonstrated for the analysis of channel-plasmon-polariton guided modes in triangular groves on a metal surface. The presented method can be used for a range of waveguide problems that were previously unsolvable analytically, due to complex geometries, or numerically, due to computational requirements of conventional three-dimensional finite-difference time-domain methods. A three-dimensional finite-difference time-domain algorithm that also allows analysis in the presence of bound or free electric and equivalent magnetic charges is presented and an example negative refraction demonstrates the method.

Pile, D. F. P.

2005-09-01

80

Fibroblast growth factor-4 induces vascular permeability, angiogenesis, and arteriogenesis in a rabbit hind limb ischemia model  

Microsoft Academic Search

Previous studies have shown that fibroblast growth factor (FGF)-1, FGF-2, and FGF-5 induce therapeutic angiogenesis. Here, we investigated the potential of FGF-4 for therapeutic neovascularization in comparison to vascular endothelial growth factor (VEGF), using adenoviral gene transfer in a novel rabbit hind limb ischemia model, with ischemia restricted to the calf. Magnetic resonance imaging and a modified Miles assay showed

Tuomas T. Rissanen; Johanna E. Markkanen; Katja Arve; Juha Rutanen; Mikko I. Kettunen; Ismo Vajanto; Suvi Jauhiainen; Linda Cashion; Marcin Gruchala; Outi Närvänen; Pekka Taipale; Risto A. Kauppinen; Gabor M. Rubanyi; Seppo Ylä-Herttuala

2002-01-01

81

Exendin-4 alleviates retinal vascular leakage by protecting the blood-retinal barrier and reducing retinal vascular permeability in diabetic Goto-Kakizaki rats.  

PubMed

The breakdown of the inner endothelial blood-retinal barrier (BRB) and subsequent retinal vascular leakage are the main causes of vision loss due to diabetic retinopathy (DR). Exendin-4 (E4) is a long-acting agonist of the glucagon-like peptide 1 hormone receptor (GLP-1R) that is widely used in clinics and has shown a neuroprotective effect. Our previous studies demonstrated the protective effect of E4 in early experimental DR; however, the molecular and cellular mechanisms that mediate this protective effect are not fully known. The BRB plays a key role in DR. We speculated that E4 may exert its protective effects on the BRB. To test this hypothesis, E4 (0.1 ?g/2 ?L/eye) or vehicle were intravitreally injected into diabetic Goto-Kakizaki(GK) rats and control animals. The results revealed that E4 significantly inhibited the reductions in electroretinogram (ERG) amplitudes in the GK rats, particularly in the b-wave and oscillatory potentials (OPs). E4 upregulated retinal GLP-1R expression and downregulated the expressions of placental growth factor (PLGF) and vascular endothelial growth factor (VEGF) via the ERK and AKT/PKB pathways. Decreases in tight junction protein (i.e., claudin-5 and occludin) expression and increases in Evans blue permeation (EBP) were inhibited by E4. Similar results were also found in primary rat Müller cells in high glucose concentration cultures in vitro. We conclude that E4 may protect the BRB from diabetic insults by decreasing PLGF and ICAM-1 expression and maintaining the integrity of the BRB. Thus, E4 treatment may be an effective therapeutic approach for DR. PMID:24910901

Fan, Yichao; Liu, Kun; Wang, Qingping; Ruan, Yuanyuan; Ye, Wen; Zhang, Yu

2014-10-01

82

Transforming growth factor-alpha-induced transcriptional activation of the vascular permeability factor (VPF/VEGF) gene requires AP-2-dependent DNA binding and transactivation.  

PubMed Central

The endothelial cell-specific mitogen vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) represents a central regulator of cutaneous angiogenesis. Increased VPF/VEGF expression has recently been reported in psoriatic skin and healing wounds, both conditions in which transforming growth factor-alpha (TGF alpha) and its ligand, the epidermal growth factor receptor, are markedly up-regulated. Since TGF alpha strongly induces VPF/VEGF synthesis in keratinocytes, TGF alpha-mediated VPF/VEGF expression is likely to play a significant role in the initiation and maintenance of increased vascular hyperpermeability and hyperproliferation in skin biology. The objectives of the present studies were to determine the molecular mechanisms responsible for TGF alpha-induced transcriptional activation of the VPF/VEGF gene. We have identified a GC-rich TGF alpha-responsive region between -88 bp and -65 bp of the VPF/VEGF promoter that is necessary for constitutive and TGF alpha-inducible transcriptional activation. In electrophoretic mobility shift assays, this region binds Sp1-dependent protein complexes constitutively and an additional TGF alpha-inducible protein complex that is distinct from Sp1 protein. Both AP-2 and Egr-1 transcription factors were detected as components of the TGF alpha-inducible protein complex in supershift EMSA studies. In co-transfection studies, an AP-2 but not an Egr-1 expression vector activated VPF/VEGF transcription, thus indicating that AP-2 protein is functionally important in TGF alpha-induced VPF/VEGF gene expression. By clarifying regulatory mechanisms that are critical for angiogenic processes in the skin, these studies may form the basis for new therapeutic strategies to modulate VPF/VEGF expression in cutaneous inflammation and wound healing. PMID:9049304

Gille, J; Swerlick, R A; Caughman, S W

1997-01-01

83

Cardioankle vascular index evaluations revealed that cotreatment of ARB Antihypertension medication with traditional Chinese medicine improved arterial functionality.  

PubMed

Qian Yang He Ji (QYHJ) is a traditional Chinese medicine composed of Digitalis purpurea, Uncaria gambir, Fructus tribuli terrestris, and Ligustrum lucidum. Here, we explored whether combining an antihypertensive angiotensin II receptor blocker (ARB) therapy with QYHJ can improve the arterial functionality of hypertensive patients. One hundred and eight hypertensive patients were randomized into 2 groups; 1 group (n = 53) was treated with ARB and the other group (n = 55) was treated with ARB combined with QYHJ. Each of the 2 groups included 3 subgroups (pure hypertension, hypertension with diabetes, and hypertension with coronary heart disease) and was further divided into patients with and without complications. The cardioankle vascular index and intima-media thickness and pulse pressure were the outcome evaluation parameter. Combined QYHJ and ARB treatment reduced the values of cardioankle vascular index, systolic blood pressure, diastolic blood pressure, and pulse pressure to significantly lower levels than ARB treatment alone did in hypertension patients after 6 months of treatment. ARB improves hypertension, but a combined QYHJ treatment can additionally ameliorate the arterial functionality not only in solely hypertensive patients but also in hypertensive patients with diabetes and coronary heart disease complications. QYHJ coapplication might be a choice to further improve the arterial functionality during an ARB hypertension treatment. PMID:23188130

Xu, Yan; Yan, Hua; Yao, Min J; Ma, Jie; Jia, Jun M; Ruan, Fen X; Yao, Zeng C; Huang, Hua M; Zheng, Jing; Chen, Ting; Lv, Hua; Endler, Alexander M

2013-05-01

84

Evaluation of Blood Pressure Control using a New Arterial Stiffness Parameter, Cardio-ankle Vascular Index (CAVI)  

PubMed Central

Arterial stiffness has been known to be a surrogate marker of arteriosclerosis, and also of vascular function. Pulse wave velocity (PWV) had been the most popular index and was known to be a predictor of cardiovascular events. But, it depends on blood pressure at measuring time. To overcome this problem, cardio-ankle vascular index (CAVI) is developed. CAVI is derived from stiffness parameter ? by Hayashi, and the equation of Bramwell-Hill, and is independent from blood pressure at a measuring time. Then, CAVI might reflect the proper change of arterial wall by antihypertensive agents. CAVI shows high value with aging and in many arteriosclerotic diseases and is also high in persons with main coronary risk factors. Furthermore, CAVI is decreased by an administration of ?1 blocker, doxazosin for 2-4 hours, Those results suggested that CAVI reflected the arterial stiffness composed of organic components and of smooth muscle cell contracture. Angiotensin II receptor blocker, olmesartan decreased CAVI much more than that of calcium channel antagonist, amlodipine, even though the rates of decreased blood pressure were almost same. CAVI might differentiate the blood pressure-lowering agents from the point of the effects on proper arterial stiffness. This paper reviewed the principle and rationale of CAVI, and the possibilities of clinical applications, especially in the studies of hypertension. PMID:23807874

Shirai, Kohji; Utino, Junji; Saiki, Atsuhito; Endo, Kei; Ohira, Masahiro; Nagayama, Daiji; Tatsuno, Ichiro; Shimizu, Kazuhiro; Takahashi, Mao; Takahara, Akira

2013-01-01

85

Discriminant Analysis of Xenon-133 Washout Curves, An Index of Lower Extremity Vascular Impairment  

PubMed Central

To evaluate the degree of vascular impairment in muscles of the lower extremity, xenon-133 washout was studied in a group of legs with impaired circulation and in another group with normal circulation during both resting and stressed conditions. Blood flow was computed as a discrete time function based on a single compartment model with time-varying flow. Linear discriminant analysis was performed, using the flows at the discrete times as discriminators. The resulting discriminant coefficients allow any leg so studied to be represented as a point on the discriminant score axis, which thus becomes the axis of severity of impairment.

Wilson, P. David; Fallon, F. Graham; Buddemeyer, Edward U.

1977-01-01

86

Inflammatory oedema induced by synergism between calcitonin gene-related peptide (CGRP) and mediators of increased vascular permeability.  

PubMed Central

The potent vasodilator calcitonin gene-related peptide (CGRP, human synthetic), when mixed with histamine and injected intradermally in the rabbit, induced a marked potentiation of local oedema. CGRP also potentiated oedema induced by other mediators of increased microvascular permeability in the rabbit; bradykinin, platelet-activating factor (Paf), C5a des Arg, N-formylmethionyl-leucyl-phenylalanine (FMLP) and leukotriene B4 (LTB4). Substance P alone, or mixtures of substance P and CGRP, failed to induce oedema in rabbit skin. In rat skin, however, substance P induced oedema and this was potentiated by CGRP. CGRP had a protracted potentiating action following intradermal injection in the rabbit. The time for half loss of activity for CGRP was 40.1 +/- 7.5 min compared to 18 +/- 1 min for prostaglandin E2 (PGE2). No loss of potentiating activity was detected after incubation of CGRP in rabbit plasma or blood for 60 min. We postulate that endogenous CGRP, if released locally from nerve endings, could have a marked enhancing effect on oedema induced by other mediators in an inflammatory reaction. PMID:2416378

Brain, S. D.; Williams, T. J.

1985-01-01

87

Temporal effects of vascular endothelial growth factor and 3,5-cyclic monophosphate on blood-brain barrier solute permeability in vivo.  

PubMed

To test the hypothesis that vascular endothelial growth factor (VEGF) can transiently increase the blood-brain barrier permeability, P, as for peripheral microvessels and that the elevation of 3,5-cyclic monophosphate (cAMP) levels can inhibit the VEGF-induced acute hyperpermeability, we employed multiphoton microscopy to quantify the cerebral microvessel permeability P to various-sized solutes under VEGF and cAMP treatments. The cerebral microcirculation was observed through a section of frontoparietal bone thinned with a microgrinder. Fluorescein (MW 376Da), fluorescein isothioyanate-dextran-20k (FITC-Dex-20k), FITC-Dex-70k, or Alexa Fluor 488-IgG in 1% bovine serum albumin mammalian Ringer's solution was injected into the cerebral circulation via the ipsilateral carotid artery with a syringe pump. Simultaneously, temporal images were collected from the brain parenchyma ?100-200 ?m below the pia mater. P was determined from the rate of tissue solute accumulation around individual microvessels. Exposure to 1 nM VEGF transiently increased P to 2.2, 10.5, 9.8, and 12.8 times control values, for fluorescein, Dex-20k, Dex-70k, and IgG, respectively, within 30 sec, and all returned to control levels within 2 min. After 20 min of pretreatment with 2 mM of the cAMP analog 8-bromo-cAMP, the initial increase by 1 nM VEGF was completely abolished in P of all solutes. The response pattern of P to VEGF and cAMP and the ratios of the peak to control values for rat cerebral microvessels are similar to those for rat mesenteric (peripheral) microvessels, except that the ratios are higher in P of cerebral microvessels for the intermediate and large solutes. These results imply a new approach for delivering large therapeutic agents to the brain. © 2014 Wiley Periodicals, Inc. PMID:25066133

Shi, Lingyan; Zeng, Min; Fu, Bingmei M

2014-12-01

88

ICAM-2 regulates vascular permeability and N-cadherin localization through ezrin-radixin-moesin (ERM) proteins and Rac-1 signalling  

PubMed Central

Background Endothelial junctions control functions such as permeability, angiogenesis and contact inhibition. VE-Cadherin (VECad) is essential for the maintenance of intercellular contacts. In confluent endothelial monolayers, N-Cadherin (NCad) is mostly expressed on the apical and basal membrane, but in the absence of VECad it localizes at junctions. Both cadherins are required for vascular development. The intercellular adhesion molecule (ICAM)-2, also localized at endothelial junctions, is involved in leukocyte recruitment and angiogenesis. Results In human umbilical vein endothelial cells (HUVEC), both VECad and NCad were found at nascent cell contacts of sub-confluent monolayers, but only VECad localized at the mature junctions of confluent monolayers. Inhibition of ICAM-2 expression by siRNA caused the appearance of small gaps at the junctions and a decrease in NCad junctional staining in sub-confluent monolayers. Endothelioma lines derived from WT or ICAM-2-deficient mice (IC2neg) lacked VECad and failed to form junctions, with loss of contact inhibition. Re-expression of full-length ICAM-2 (IC2 FL) in IC2neg cells restored contact inhibition through recruitment of NCad at the junctions. Mutant ICAM-2 lacking the binding site for ERM proteins (IC2 ?ERM) or the cytoplasmic tail (IC2 ?TAIL) failed to restore junctions. ICAM-2-dependent Rac-1 activation was also decreased in these mutant cell lines. Barrier function, measured in vitro via transendothelial electrical resistance, was decreased in IC2neg cells, both in resting conditions and after thrombin stimulation. This was dependent on ICAM-2 signalling to the small GTPase Rac-1, since transendothelial electrical resistance of IC2neg cells was restored by constitutively active Rac-1. In vivo, thrombin-induced extravasation of FITC-labeled albumin measured by intravital fluorescence microscopy in the mouse cremaster muscle showed that permeability was increased in ICAM-2-deficient mice compared to controls. Conclusions These results indicate that ICAM-2 regulates endothelial barrier function and permeability through a pathway involving N-Cadherin, ERMs and Rac-1. PMID:24593809

2014-01-01

89

Publicações indexadas geradas a partir de resumos de congressos de angiologia e cirurgia vascular no Brasil Indexed publications generated from abstracts of angiology and vascular surgery congresses in Brazil  

Microsoft Academic Search

Background: Great part of the scientific production presented in congresses is not published. Even in developed countries, figures show an expressive difference between presentations and publications. Objective: To evaluate the number of published and indexed articles, based on available national and international databases, searching for titles and authors of papers and panels from Brazilian vascular surgery congresses held in 2001

Winston Bonetti Yoshida; Nicole França Holmo; Gabriela Tieme Corregliano; Karina Marcellino Baldon

90

Novel Application of a Multiscale Entropy Index as a Sensitive Tool for Detecting Subtle Vascular Abnormalities in the Aged and Diabetic  

PubMed Central

Although previous studies have shown the successful use of pressure-induced reactive hyperemia as a tool for the assessment of endothelial function, its sensitivity remains questionable. This study aims to investigate the feasibility and sensitivity of a novel multiscale entropy index (MEI) in detecting subtle vascular abnormalities in healthy and diabetic subjects. Basic anthropometric and hemodynamic parameters, serum lipid profiles, and glycosylated hemoglobin levels were recorded. Arterial pulse wave signals were acquired from the wrist with an air pressure sensing system (APSS), followed by MEI and dilatation index (DI) analyses. MEI succeeded in detecting significant differences among the four groups of subjects: healthy young individuals, healthy middle-aged or elderly individuals, well-controlled diabetic individuals, and poorly controlled diabetic individuals. A reduction in multiscale entropy reflected age- and diabetes-related vascular changes and may serve as a more sensitive indicator of subtle vascular abnormalities compared with DI in the setting of diabetes. PMID:23509600

Wu, Hsien-Tsai; Lo, Men-Tzung; Chen, Guan-Hong; Sun, Cheuk-Kwan; Chen, Jian-Jung

2013-01-01

91

Systemic vascular resistance index determined by thoracic electrical bioimpedance predicts the risk for maternal hypotension during regional anesthesia for cesarean delivery  

Microsoft Academic Search

OBJECTIVE: Our purpose was to evaluate the predictive value of the baseline systemic vascular resistance index for the development of maternal hypotension during regional anesthesia for cesarean delivery. STUDY DESIGN: Patients receiving a standardized spinal or epidural anesthetic for nonemergency cesarean delivery were studied prospectively. Hemodynamic data were obtained noninvasively with an NCCOM-3 cardiac output monitor (Bomed Medical Manufacturing, Irvine,

Joseph G. Ouzounian; Damon I. Masaki; Therese K. Abboud; Jeffrey S. Greenspoon

1996-01-01

92

Accuracy of Doppler-derived estimation of pulmonary vascular resistance in congenital heart disease: an index of operability.  

PubMed

Pulmonary vascular resistance (PVR) is a critical and essential parameter during the assessment and selection of modality of treatment in patients with congenital heart disease (CHD) accompanied by pulmonary arterial hypertension (PAH). Cardiac catheterization is the "gold standard" but is an invasive method for PVR measurement. A noninvasive and reliable method for estimation of PVR in children has been a major challenge and most desirable during past decades, especially for those who need repeated measurements. In a prospective study and among consecutive patients who were referred for cardiac catheterizations, PVR was calculated as the ratio of the transpulmonary pressure gradient (?P) to the amount of the pulmonary flow (QP) accordingly for 20 patients with CHD and high PAH. Subsequently and noninvasively, PVR was assessed for these patients by a Doppler echocardiography-derived index defined as the ratio of the tricuspid regurgitation velocity (TRV(m/s)) to the velocity time integral (VTI(cm)) of the right-ventricular outflow tract (RVOT). There was a good correlation between PVR measured at catheterization (PVR(cath)) and TRV/VTI(m) ratio; the mean of three measurements of VTI (VTI(m)) with R (2) = 0.53 (p = 0.008). In addition, a TRV/VTI(m) value of 0.2 provided a sensitivity of 71.4% and a specificity of 100% for PVR >6 Woods units (WU) as well as sensitivity of 90% and specificity of 90% for a PVR equal to 8 WU. PVR value between 6 and 8 WU by catheterization has been considered as a cut-off point for intervention in children with left-to-right shunts and PAH. In conclusion, Doppler-derived TRV/VTI(m) ratio is a reliable index that may be helpful as a supplementary diagnostic tool for the selection of modality of treatment and follow-up of patients with PAH and increased PVR. PMID:21779967

Ajami, Gholam Hossein; Cheriki, Sirous; Amoozgar, Hamid; Borzouee, Mohammad; Soltani, Manoucher

2011-12-01

93

Catalase and Superoxide Dismutase Conjugated with Platelet-Endothelial Cell Adhesion Molecule Antibody Distinctly Alleviate Abnormal Endothelial Permeability Caused by Exogenous Reactive Oxygen Species and Vascular Endothelial Growth Factor  

PubMed Central

Reactive oxygen species (ROS) superoxide anion (O2?) and hydrogen peroxide (H2O2) produced by activated leukocytes and endothelial cells in sites of inflammation or ischemia cause endothelial barrier dysfunction that may lead to tissue edema. Antioxidant enzymes (AOEs) catalase and superoxide dismutase (SOD) conjugated with antibodies to platelet-endothelial cell adhesion molecule-1 (PECAM-1) specifically bind to endothelium, quench the corresponding ROS, and alleviate vascular oxidative stress and inflammation. In the present work, we studied the effects of anti-PECAM/catalase and anti-PECAM/SOD conjugates on the abnormal permeability manifested by transendothelial electrical resistance decline, increased fluorescein isothiocyanate-dextran influx, and redistribution of vascular endothelial-cadherin in human umbilical vein endothelial cell (HUVEC) monolayers. Anti-PECAM/catalase protected HUVEC monolayers against H2O2-induced endothelial barrier dysfunction. Polyethylene glycol-conjugated catalase exerted orders of magnitude lower endothelial uptake and no protective effect, similarly to IgG/catalase. Anti-PECAM/catalase, but not anti-PECAM/SOD, alleviated endothelial hyperpermeability caused by exposure to hypoxanthine/xanthine oxidase, implicating primarily H2O2 in the disruption of the endothelial barrier in this model. Thrombin-induced endothelial permeability was not affected by treatment with anti-PECAM/AOEs or the NADPH oxidase inhibitor apocynin or overexpression of AOEs, indicating that the endogenous ROS play no key role in thrombin-mediated endothelial barrier dysfunction. In contrast, anti-PECAM/SOD, but not anti-PECAM/catalase, inhibited a vascular endothelial growth factor (VEGF)-induced increase in endothelial permeability, identifying a key role of endogenous O2? in the VEGF-mediated regulation of endothelial barrier function. Therefore, AOEs targeted to endothelial cells provide versatile molecular tools for testing the roles of specific ROS in vascular pathology and may be translated into remedies for these ROS-induced abnormalities. PMID:21474567

Han, Jingyan; Shuvaev, Vladimir V.

2011-01-01

94

Blood pressure-independent effect of candesartan on cardio-ankle vascular index in hypertensive patients with metabolic syndrome  

PubMed Central

Angiotensin receptor blockers (ARBs) are known to reduce the cardiovascular risk in hypertensive patients. This study was designed to examine the effect of an ARB candesartan on subclinical atherosclerosis assessed by cardio-ankle vascular index (CAVI) in comparison with calcium channel blockers (CCBs) alone in hypertensive patients with metabolic syndrome (MetS). A total of 53 consecutive hypertensive patients with MetS were randomly assigned to the candesartan group, in which candesartan was added on, or the CCBs group, in which CCBs were added on. Clinical and biological parameters were obtained before and after the 12-month treatment period. The primary measure of efficacy was the %change in CAVI. When treated with candesartan, but not CCBs, CAVI significantly decreased from 8.7 to 7.7 by 11%. Blood pressure (BP) significantly decreased with both treatments, but the differences between groups were not significant. The changes in other parameters remained unchanged in both the groups. Analysis of covariance found that both the BP reduction and the therapy difference contributed to the decrease in CAVI, but the BP reduction was not involved in the decrease in CAVI caused by the difference in the therapy. Candesartan may be a better antihypertensive drug than CCBs to improve subclinical atherosclerosis of patients with MetS. PMID:20730073

Bokuda, Kanako; Ichihara, Atsuhiro; Sakoda, Mariyo; Mito, Asako; Kinouchi, Kenichiro; Itoh, Hiroshi

2010-01-01

95

Measurement of absolute cell volume, osmotic membrane water permeability, and refractive index of transmembrane water and solute flux by digital holographic microscopy  

NASA Astrophysics Data System (ADS)

A dual-wavelength digital holographic microscope to measure absolute volume of living cells is proposed. The optical setup allows us to reconstruct two quantitative phase contrast images at two different wavelengths from a single hologram acquisition. When adding the absorbing dye fast green FCF as a dispersive agent to the extracellular medium, cellular thickness can be univocally determined in the full field of view. In addition to the absolute cell volume, the method can be applied to derive important biophysical parameters of living cells including osmotic membrane water permeability coefficient and the integral intracellular refractive index (RI). Further, the RI of transmembrane flux can be determined giving an indication about the nature of transported solutes. The proposed method is applied to cultured human embryonic kidney cells, Chinese hamster ovary cells, human red blood cells, mouse cortical astrocytes, and neurons.

Boss, Daniel; Kühn, Jonas; Jourdain, Pascal; Depeursinge, Christian; Magistretti, Pierre J.; Marquet, Pierre

2013-03-01

96

Vascular involvement in rheumatic diseases: 'vascular rheumatology'  

Microsoft Academic Search

The vasculature plays a crucial role in inflammation, angiogenesis, and atherosclerosis associated with the pathogenesis of inflammatory rheumatic diseases, hence the term 'vascular rheumatology'. The endothelium lining the blood vessels becomes activated during the inflammatory process, resulting in the production of several mediators, the expression of endothelial adhesion molecules, and increased vascular permeability (leakage). All of this enables the extravasation

Zoltán Szekanecz; Alisa E Koch

2008-01-01

97

Determination of permeability index using Stoneley slowness analysis, NMR models, and formation evaluations: a case study from a gas reservoir, south of Iran  

NASA Astrophysics Data System (ADS)

In hydrocarbon reservoirs, permeability is one of the most critical parameters with a significant role in the production of hydrocarbon resources. Direct determination of permeability using Stoneley waves has always had some difficulties. In addition, some un-calibrated empirical models such as Nuclear Magnetic Resonance (NMR) models and petrophysical evaluation model (intrinsic permeability) do not provide reliable estimates of permeability in carbonate formations. Therefore, utilizing an appropriate numerical method for direct determination of permeability using Stoneley waves as well as an appropriate calibration method for the empirical models is necessary to have reliable results. This paper shows the application of a numerical method, called bisection method, in the direct determination of permeability from Stoneley wave slowness. In addition, a linear regression (least squares) method was used to calibrate the NMR models including Schlumberger Doll Research (SDR) and Timur-Coates models as well as the intrinsic permeability equation (permeability from petrophysical evaluations). The Express Pressure Tester (XPT) permeability was considered as an option for the reference permeability. Therefore, all permeability models were validated for the Stoneley permeability and calibrated for the empirical models with the XPT permeability. In order to have a quantitative assessment on the results and compare the results before and after the calibration, the Root Mean Squares Error (RMSE) was calculated for each of the used models. The results for the Stoneley permeability showed that, in many points there was not much difference between the Stoneley permeability calculated by the bisection method and the XPT permeability. Comparing the results showed that the calibration of the empirical models reduced their RMSE values. As a result of the calibration, the RMSE was decreased by about 39% for the SDR model, 18% for the Timur-Coates model, and 91% for the petrophysical evaluations model. Presented bisection method calculates permeability directly without of any inversion or external calibration.

Hosseini, Mirhasan; Javaherian, Abdolrahim; Movahed, Bahram

2014-10-01

98

Opposite responses of vascular and moss communities to1 changes in humus form, as expressed by the Humus Index2  

E-print Network

communities. In short, at a given point, the more diverse plant, microbial and animal6 communities, the more1 Opposite responses of vascular and moss communities to1 changes in humus form, as expressed inventoried in two6 broadleaved forests, with contrasting soil conditions. Fifteen and sixteen sites were7

99

Permeability Test  

NSDL National Science Digital Library

This resource from the Indian Institute of Technology Kanpur provides an outline of constant head and falling head permeability tests of soil. This is a great resource for anyone studying geology and soil science.

2008-05-16

100

Permeable Pavement  

NSDL National Science Digital Library

Students investigate how different riparian ground covers, such as grass or pavement, affect river flooding. They learn about permeable and impermeable materials through the measurement how much water is absorbed by several different household materials in a model river. Students use what they learn to make recommendations for engineers developing permeable pavement. Also, they consider several different limitations for design in the context of a small community.

Integrated Teaching And Learning Program

101

Survey of ocular irritation predictive capacity using Chorioallantoic Membrane Vascular Assay (CAMVA) and Bovine Corneal Opacity and Permeability (BCOP) test historical data for 319 personal care products over fourteen years.  

PubMed

The Chorioallantoic Membrane Vascular Assay (CAMVA) and Bovine Corneal Opacity and Permeability (BCOP) test are widely used to predict ocular irritation potential for consumer-use products. These in vitro assays do not require live animals, produce reliable predictive data for defined applicability domains compared to the Draize rabbit eye test, and are rapid and inexpensive. Data from 304 CAMVA and/or BCOP studies (319 formulations) were surveyed to determine the feasibility of predicting ocular irritation potential for various formulations. Hair shampoos, skin cleansers, and ethanol-based hair styling sprays were repeatedly predicted to be ocular irritants (accuracy rate=0.90-1.00), with skin cleanser and hair shampoo irritation largely dependent on surfactant species and concentration. Conversely, skin lotions/moisturizers and hair styling gels/lotions were repeatedly predicted to be non-irritants (accuracy rate=0.92 and 0.82, respectively). For hair shampoos, ethanol-based hair stylers, skin cleansers, and skin lotions/moisturizers, future ocular irritation testing (i.e., CAMVA/BCOP) can be nearly eliminated if new formulations are systematically compared to those previously tested using a defined decision tree. For other tested product categories, new formulations should continue to be evaluated in CAMVA/BCOP for ocular irritation potential because either the historical data exhibit significant variability (hair conditioners and mousses) or the historical sample size is too small to permit definitive conclusions (deodorants, make-up removers, massage oils, facial masks, body sprays, and other hair styling products). All decision tree conclusions should be made within a conservative weight-of-evidence context, considering the reported limitations of the BCOP test for alcohols, ketones, and solids. PMID:21147215

Donahue, D A; Kaufman, L E; Avalos, J; Simion, F A; Cerven, D R

2011-03-01

102

Mechanisms of Tumor Vascular Priming by a Nanoparticulate Doxorubicin Formulation  

PubMed Central

Purpose Tumor vascular normalization by antiangiogenic agents may increase tumor perfusion but reestablish vascular barrier properties in CNS tumors. Vascular priming via nanoparticulate carriers represents a mechanistically distinct alternative. This study investigated mechanisms by which sterically-stabilized liposomal doxorubicin (SSL-DXR) modulates tumor vascular properties. Methods Functional vascular responses to SSL-DXR were investigated in orthotopic rat brain tumors using deposition of fluorescent permeability probes and dynamic contrast-enhanced magnetic resonance imaging. Microvessel density and tumor burden were quantified by immunohistochemistry (CD-31) and quantitative RT-PCR (VE-cadherin). Results Administration of SSL-DXR (5.7 mg/kg iv) initially (3–4 days post-treatment) decreased tumor vascular permeability, ktrans (vascular exchange constant), vascular endothelial cell content, microvessel density, and deposition of nanoparticulates. Tumor vasculature became less chaotic. Permeability and perfusion returned to control values 6–7 days post-treatment, but intratumor SSL-DXR depot continued to effect tumor vascular endothelial compartment 7–10 days post-treatment, mediating enhanced permeability. Conclusions SSL-DXR ultimately increased tumor vascular permeability, but initially normalized tumor vasculature and decreased tumor perfusion, permeability, and nanoparticulate deposition. These temporal changes in vascular integrity resulting from a single SSL-DXR dose have important implications for the design of combination therapies incorporating nanoparticle-based agents for tumor vascular priming. PMID:22798260

Chaudhuri, Tista Roy; Arnold, Robert D.; Yang, Jun; Turowski, Steven G.; Qu, Yang; Spernyak, Joseph A.; Mazurchuk, Richard; Mager, Donald E.

2013-01-01

103

Cerebral changes in chronic hypertension: Combined permeability and immunohistochemical studies  

Microsoft Academic Search

Focal areas of recent and old necrosis are a consistent finding in brain in chronic hypertension. The possibility that areas represent foci of increased vascular permeability leading to chronic edema and tissue breakdown was investigated in the present study.

S. Nag

1984-01-01

104

Vascular ring  

MedlinePLUS

... congenital heart problems. The condition occurs as often in males as females. Some infants with vascular ring also have another congenital heart problem. Vascular ring occurs very early in the baby's development in the womb. Normally, the ...

105

Vascular Hyperpermeability, Angiogenesis, and Stroma Generation  

PubMed Central

It has been known for more than half a century that the tumor microvasculature is hyperpermeable to plasma proteins. However, the identity of the leaky vessels and the consequences of vascular hyperpermeability have received little attention. This article places tumor vascular hyperpermeability in a broader context, relating it to (1) the low-level “basal” permeability of the normal vasculature; (2) the “acute,” short-term hyperpermeability induced by vascular permeability factor/vascular endothelial growth factor (VPF/VEGF-A) and other vascular permeabilizing agents; and (3) the “chronic” hyperpermeability associated with longer-term exposure to agents such as VPF/VEGF-A that accompanies many types of pathological angiogenesis. Leakage of plasma protein-rich fluids is important because it activates the clotting system, depositing an extravascular fibrin gel provisional matrix that serves as the first step in stroma generation. PMID:22355795

Nagy, Janice A.; Dvorak, Ann M.; Dvorak, Harold F.

2012-01-01

106

A Warning Index Used in Prescreening for Alzheimer's Disease, Based on Self-Reported Cognitive Deficits and Vascular Risk Factors for Dementia in Elderly Patients with Type 2 Diabetes  

PubMed Central

Background/Aims. Diabetes might increase the risk of Alzheimer's disease (AD). For detecting dementia, it is typical to obtain informants' perceptions of cognitive deficits, but such interviews are usually difficult in routine care. We aimed to develop a model for predicting mild to moderate AD using a self-reported questionnaire and by evaluating vascular risk factors for dementia in elderly subjects with diabetes. Methods. We recruited 286 diabetic and 155 nondiabetic elderly subjects. There were 25 patients with AD and 261 cognitively normal individuals versus 30 with AD and 125 normal subjects, respectively. Each participant answered subjective questions on memory deficits and daily functioning. Information on vascular risk factors was obtained from clinical charts, and multivariate logistic regression was used to develop a model for predicting AD. Results. The predicted probabilities used in screening for AD in diabetic subjects constituted age, education, lower diastolic blood pressure, subjective complaints of memory dysfunction noticeable by others, and impaired medication, shopping, and travel outside a familiar locality. Receiver operating characteristic analysis revealed a satisfactory discrimination for AD specific for diabetic elderly subjects, with 95.2% sensitivity and 90.6% specificity. Conclusion. This is the first useful index that can prescreen for AD in elderly subjects with diabetes. PMID:23119223

Matsuzawa, Toshioki; Takata, Toshihiro; Yokono, Koichi; Ueda, Hiroo; Moriwaki, Kensuke; Kamae, Isao; Urakami, Katsuya; Sakurai, Takashi

2012-01-01

107

Circulating vascular endothelial growth factor is not increased during relapses of steroid-sensitive nephrotic syndrome  

Microsoft Academic Search

Circulating vascular endothelial growth factor is not increased during relapses of steroid-sensitive nephrotic syndrome.Background.An uncharacterized circulating factor that increases vascular permeability has previously been described in childhood steroid-sensitive nephrotic syndrome (SSNS). The aim of this study was to determine whether this factor is vascular endothelial growth factor (VEGF), the recently described endothelial cell mitogen and enhancer of vascular permeability.Methods.Plasma and

NICHOLAS J. A. WEBB; CAROLYN J. WATSON; IAN S. D. ROBERTS; MARTYN J. BOTTOMLEY; CAROLINE A. JONES; MALCOLM A. LEWIS; ROBERT J. POSTLETHWAITE; PAUL E. C. BRENCHLEY

1999-01-01

108

Ageing and vascular ageing  

PubMed Central

There is an age related decline in various physiological processes. Vascular ageing is associated with changes in the mechanical and the structural properties of the vascular wall, which leads to the loss of arterial elasticity and reduced arterial compliance. Arterial compliance can be measured by different parameters like pulse wave velocity, augmentation index, and systemic arterial compliance. There is evidence that arterial compliance is reduced in disease states such as hypertension, diabetes, and end stage renal failure. Changes in arterial compliance can be present before the clinical manifestation of cardiovascular disease. Pharmacological and non?pharmacological measures have been shown to improve arterial compliance. Arterial compliance may constitute an early cardiovascular risk marker and may be useful in assessing the effects of drugs on the cardiovascular system. Pharmacogenetics and genetics of arterial compliance in the future will improve our knowledge and understanding about vascular ageing. PMID:16754702

Jani, B; Rajkumar, C

2006-01-01

109

Vascular Diseases  

MedlinePLUS

... affects the heart and blood vessels, such as diabetes or high cholesterol Smoking Obesity Losing weight, eating healthy foods, being active and not smoking can help vascular disease. Other treatments include medicines and surgery.

110

Vascular Cures  

MedlinePLUS

... Learn more here . @ 2014 Vascular Cures is a tax-exempt, nonprofit organization tax ID#: 94-2825216 as described in the Section ... 3) of the Internal Revenue Code. Donations are tax deductible. 555 Price Ave., Suite 180, Redwood City, ...

111

Influence of salinity on permeability characteristics of marine sediments  

Microsoft Academic Search

Laboratory tests were conducted on compacted marine sediments to study the effect of salt concentration of permeating fluid on its permeability characteristics. Deep sea sediment samples were collected from water depths varying from 3700 to 4500 m off Mauritius coast. Liquid limit and plasticity index varied widely from 45 to 75 and 10 to 35, respectively. Permeability was found at

U. V. Jose; S. T. Bhat; B. U. Nayak

1989-01-01

112

Vascular Calcification  

PubMed Central

Summary Clinically, vascular calcification is now accepted as a valuable predictor of coronary heart disease.153 Achieving control over this process requires understanding mechanisms in the context of a tightly controlled regulatory network, with multiple, nested feedback loops and cross talk between organ systems, in the realm of control theory. Thus, treatments for osteoporosis such as calcitriol, estradiol, bisphosphonates, calcium supplements, and intermittent PTH are likely to affect vascular calcification, and, conversely, many treatments for cardiovascular disease such as statins, antioxidants, hormone replacement therapy, angiotensin-converting enzyme inhibitors, fish oils, and calcium channel blockers may affect bone health. As we develop and use treatments for cardiovascular and skeletal diseases, we must give serious consideration to the implications for the organ at the other end of the bone-vascular axis. PMID:11602487

Demer, Linda L.; Tintut, Yin

2009-01-01

113

Vascular involvement in rheumatic diseases: 'vascular rheumatology'  

PubMed Central

The vasculature plays a crucial role in inflammation, angiogenesis, and atherosclerosis associated with the pathogenesis of inflammatory rheumatic diseases, hence the term 'vascular rheumatology'. The endothelium lining the blood vessels becomes activated during the inflammatory process, resulting in the production of several mediators, the expression of endothelial adhesion molecules, and increased vascular permeability (leakage). All of this enables the extravasation of inflammatory cells into the interstitial matrix. The endothelial adhesion and transendothelial migration of leukocytes is a well-regulated sequence of events that involves many adhesion molecules and chemokines. Primarily selectins, integrins, and members of the immunoglobulin family of adhesion receptors are involved in leukocyte 'tethering', 'rolling', activation, and transmigration. There is a perpetuation of angiogenesis, the formation of new capillaries from pre-existing vessels, as well as that of vasculogenesis, the generation of new blood vessels in arthritis and connective tissue diseases. Several soluble and cell-bound angiogenic mediators produced mainly by monocytes/macrophages and endothelial cells stimulate neovascularization. On the other hand, endogenous angiogenesis inhibitors and exogenously administered angiostatic compounds may downregulate the process of capillary formation. Rheumatoid arthritis as well as systemic lupus erythematosus, scleroderma, the antiphospholipid syndrome, and systemic vasculitides have been associated with accelerated atherosclerosis and high cardiovascular risk leading to increased mortality. Apart from traditional risk factors such as smoking, obesity, hypertension, dyslipidemia, and diabetes, inflammatory risk factors, including C-reactive protein, homocysteine, folate deficiency, lipoprotein (a), anti-phospholipid antibodies, antibodies to oxidized low-density lipoprotein, and heat shock proteins, are all involved in atherosclerosis underlying inflammatory rheumatic diseases. Targeting of adhesion molecules, chemokines, and angiogenesis by administering nonspecific immunosuppressive drugs as well as monoclonal antibodies or small molecular compounds inhibiting the action of a single mediator may control inflammation and prevent tissue destruction. Vasoprotective agents may help to prevent premature atherosclerosis and cardiovascular disease. PMID:18947376

Szekanecz, Zoltan; Koch, Alisa E

2008-01-01

114

The Vascular Flora Andros Island, Bahamas  

E-print Network

#12;The Vascular Flora of Andros Island, Bahamas by Daniel L. Nickrent University of Illinois and W on This Version of the Book The original edition of "Vascular Flora of Andros Island, Bahamas" by D. L. Nickrent differs from the original in that an index to common names of Andros plants was added. This list

Nickrent, Daniel L.

115

Vascular endothelial growth factor production and regulation in human peritoneal mesothelial cells  

Microsoft Academic Search

Vascular endothelial growth factor production and regulation in human peritoneal mesothelial cells.BackgroundVascular endothelial growth factor (VEGF) was recently found in peritoneal effluents of peritoneal dialysis (PD) patients. It was suggested that human peritoneal mesothelial cells (HMC) contribute to the intraperitoneal production of VEGF, which may augment vascular permeability, vasodilation and neoangiogenesis in the peritoneal membrane. The present study was designed

Sonja Mandl-Weber; Clemens D. Cohen; Bettina Haslinger; Matthias Kretzler; Thomas Sitter

2002-01-01

116

Effects of inflation volume during lung preservation on pulmonary capillary permeability  

Microsoft Academic Search

The degree of lung allograft inflation during harvest and storage may affect posttransplantation function. High volume ventilation causes pulmonary vascular injury and increased pulmonary capillary permeability. However, the effect of lung inflation on pulmonary capillary permeability after hypothermic flush and storage is unknown. The current study was designed to examine the effects of hyperinflation and hypoinflation during preservation on pulmonary

Masayuki Haniuda; Seiki Hasegawa; Takeshi Shiraishi; Carolyn M. Dresler; Joel D. Cooper; G. Alexander Patterson

1996-01-01

117

Vascular sarcomas.  

PubMed

Vascular sarcomas are soft-tissue tumors that arise from the endothelium with a malignant potential. This review discusses the management of epithelioid hemangioendothelioma (EHE) and angiosarcoma. EHE is a vascular tumor of intermediate malignant potential with an indolent course. EHE arising from the liver, lung, or bone tends to be multifocal and the rate of progression is slow and often unpredictable. Treatment should be considered in patients with significant symptomatic deterioration and/or progressive disease on imaging studies. Various cytotoxic and targeted therapies are available for management, with disease stabilization as the most common outcome. Angiosarcoma is an aggressive vascular tumor with a high malignant potential. Multidisciplinary care is critical for the management of localized disease, and the best outcomes are often observed in patients when a combination of systemic and local therapy options is used. Metastatic angiosarcoma is treated primarily with systemic therapy, and several cytotoxic and targeted therapies are available, alone or in combination. The choice of therapy depends on several factors, such as cutaneous location of the tumor, performance status of the patient, toxicity of the treatment, and patient goals. PMID:23852636

Ravi, Vinod; Patel, Shreyaskumar

2013-08-01

118

Inflammatory Cytokines in Vascular Dysfunction and Vascular Disease  

PubMed Central

The vascular inflammatory response involves complex interaction between inflammatory cells (neutrophils, lymphocytes, monocytes, macrophages), endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and extracellular matrix (ECM). Vascular injury is associated with increased expression of adhesion molecules by ECs and recruitment of inflammatory cells, growth factors, and cytokines, with consequent effects on ECs, VSMCs and ECM. Cytokines include tumor necrosis factors, interleukins, lymphokines, monokines, interferons, colony stimulating factors, and transforming growth factors. Cytokines are produced by macrophages, T cells and monocytes, as well as platelets, ECs and VSMCs. Circulating cytokines interact with specific receptors on various cell types and activate JAK-STAT, NF-?B, and Smad signaling pathways leading to an inflammatory response involving cell adhesion, permeability and apoptosis. Cytokines also interact with mitochondria to increasie the production of reactive oxygen species. Cytokine-induced activation of these pathways in ECs modifies the production/activity of vasodilatory mediators such as nitric oxide, prostacyclin, endothelium-derived hyperpolarizing factor, and bradykinin, as well as vasoconstrictive mediators such as endothelin and angiotensin II. Cytokines interact with VSMCs to activate Ca2+, protein kinase C, Rho-Kinase, and MAPK pathways, which promote cell growth and migration, and VSM reactivity. Cytokines also interact with integrins and matrix metalloproteinases (MMPs) and modify ECM composition. Persistent increases in cytokines are associated with vascular dysfunction and vascular disease such as atherosclerosis, abdominal aortic aneurysm, varicose veins and hypertension. Genetic and pharmacological tools to decrease the production of cytokines or to diminish their effects using cytokine antagonists could provide new approaches in the management of inflammatory vascular disease. PMID:19413999

Sprague, Alexander H.; Khalil, Raouf A.

2009-01-01

119

Seismic waves increase permeability.  

PubMed

Earthquakes have been observed to affect hydrological systems in a variety of ways--water well levels can change dramatically, streams can become fuller and spring discharges can increase at the time of earthquakes. Distant earthquakes may even increase the permeability in faults. Most of these hydrological observations can be explained by some form of permeability increase. Here we use the response of water well levels to solid Earth tides to measure permeability over a 20-year period. At the time of each of seven earthquakes in Southern California, we observe transient changes of up to 24 degrees in the phase of the water level response to the dilatational volumetric strain of the semidiurnal tidal components of wells at the Piñon Flat Observatory in Southern California. After the earthquakes, the phase gradually returns to the background value at a rate of less than 0.1 degrees per day. We use a model of axisymmetric flow driven by an imposed head oscillation through a single, laterally extensive, confined, homogeneous and isotropic aquifer to relate the phase response to aquifer properties. We interpret the changes in phase response as due to changes in permeability. At the time of the earthquakes, the permeability at the site increases by a factor as high as three. The permeability increase depends roughly linearly on the amplitude of seismic-wave peak ground velocity in the range of 0.21-2.1 cm s(-1). Such permeability increases are of interest to hydrologists and oil reservoir engineers as they affect fluid flow and might determine long-term evolution of hydrological and oil-bearing systems. They may also be interesting to seismologists, as the resulting pore pressure changes can affect earthquakes by changing normal stresses on faults. PMID:16810253

Elkhoury, Jean E; Brodsky, Emily E; Agnew, Duncan C

2006-06-29

120

Anti-VEGF Agents for Ocular Angiogenesis and Vascular Permeability  

PubMed Central

We review articles describing intravitreal injection of anti-VEGF drug trials, while discussing the mechanisms of the action of anti-VEGF antibodies, and also evaluating their outcomes. Intraocular injections of anti-VEGF drug are considered to be an effective treatment for macular edema after retinal vein occlusion, however, recurrent/persistent edema is common. The recent reports may lead to a shift in treatment paradigm for DME, from laser photocoagulation, to newer approaches using anti-VEGF drugs. There have been several well-publicized prospective, randomized studies that demonstrated the efficacy of intravitreal injection of anti-VEGF drugs for patients with AMD. Adjuvant bevacizumab for neovascular glaucoma may prevent further PAS formation, and it is likely to open up a therapeutic window for a panretinal photocoagulation and trabeculectomy. Intravitreal injection of bevacizumab (IVB) results in a substantial decrease in bleeding from the retinal vessels or new vessels during a standard vitrectomy. IVB has also been reported to be effective for inducing the regression of new vessels in proliferative diabetic retinopathy. The use of bevacizumab in stage 4 or 5 retinopahty of permaturity (ROP) is to reduce the plus sign to help reduce hemorrhage during the subsequent vitrectomy. Some authors reported cases of resolution of stage 4?A ROP after bevacizumab injection. PMID:22132316

Kimoto, Kenichi; Kubota, Toshiaki

2012-01-01

121

Vascular cells.  

PubMed

Embryonic stem (ES) cells are cells derived from the inner cell mass of a blastocyst stage embryo. These self-renewing multipotent cells are able to differentiate to the three embryonic germ layers, the endoderm, ectoderm, and mesoderm, and are thus able to produce virtually all cell types. The ES cell capacity to generate various cell types has been studied extensively, and exploitation of ES cell characteristics allowed the production of several differentiated cell types of multiple tissues. Moreover, the process of ES cell differentiation provides a unique opportunity to observe early embryonic developmental events that are unattainable in the embryo itself. This chapter addresses the in vitro differentiation procedure of endothelial and vascular smooth muscle cells from human ES cells, with reference to similar studies performed in mouse and nonhuman primate ES cells, and provides several tools for the detailed characterization of differentiated cells. PMID:17141040

Goldberg-Cohen, Ilana; Beck, Gilad; Ziskind, Anna; Itskovitz-Eldor, Joseph

2006-01-01

122

Sac-1004, a novel vascular leakage blocker, enhances endothelial barrier through the cAMP/Rac/cortactin pathway  

E-print Network

Sac-1004, a novel vascular leakage blocker, enhances endothelial barrier through the c history: Received 27 April 2013 Available online 9 May 2013 Keywords: Sac-1004 Vascular permeability VEGF actin ring. Here, we developed a novel vascular leakage blocker, Sac-1004 and investigated its mechanism

Suh, Young-Ger

123

Transient increase in interleukin-8 and pulmonary microvascular permeability following aortic surgery.  

PubMed

Aortic surgery results in ischemia/reperfusion of the lower body. This may liberate inflammatory mediators that activate neutrophils, and may result in lung microvascular changes with increased permeability and respiratory failure. We studied circulating inflammatory mediators and the pulmonary leak index (PLI) of 67Ga, a measure of transvascular transferrin transport and permeability, in patients scheduled for elective aortic and peripheral vascular surgery, before and after surgery. Aortic surgery patients in Groups 1 (n = 10) and 2 (n = 7) were studied before and at a median of 2.5 and 21.0 h after surgery, respectively. A control Group 3 (n = 6) was studied before and at a median of 2.9 h after peripheral vascular surgery. The PLI (median) increased from a median of 9.1 (range, 6.6 to 14.7) before to a median of 23.4 (range, 18.7 to 86.4) x 10(-3)/min after surgery in Group 1 but not in the other groups (p < 0.001). The postoperative increase in circulating neutrophils and elastase-alpha 1-antitrypsin, a marker of neutrophil activation, was similar among the groups. Plasma levels of activated complement 3a and tumor necrosis factor (TNF-alpha) did not change in any of the groups. In contrast, plasma levels of interleukin-8 (IL-8) increased in Group 1 from < 3 (range, < 3 to 37) before to 324 (range, 36 to 868) pg/ml after surgery, but did not change in the other groups (p < 0.005). The decrease in plasma levels of angiotensin converting enzyme (ACE) was greater in Group 1 than in the other groups (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7881659

Raijmakers, P G; Groeneveld, A B; Rauwerda, J A; Schneider, A J; Teule, G J; Hack, C E; Thijs, L G

1995-03-01

124

Relative Permeability Through Fractures  

E-print Network

SGP-TR-170 Relative Permeability Through Fractures Gracel P. Diomampo August 2001 Financial support, California #12;#12;v Abstract The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood

Stanford University

125

SWIMBLADDER PERMEABILITY TO OXYGEN  

Microsoft Academic Search

SUMMARY The permeability of the swimbladder to gas was measured as the conductance to oxygen in seven species of fish. The low over-all conductance resides in the low diffusion constant, K, of the middle layer of the wall (submucosa) while the outer and inner layers (tunica externa and mucosa) have diffusion constants similar to other vertebrate tissues. The low diffusion

GEORGE N. LAPENNAS; KNUT SCHMIDT-NIELSEN

1977-01-01

126

Intraocular Hemorrhage Causes Retinal Vascular Dysfunction via Plasma Kallikrein  

PubMed Central

Purpose. Retinal hemorrhages occur in a variety of sight-threatening conditions including ocular trauma, high altitude retinopathy, and chronic diseases such as diabetic and hypertensive retinopathies. The goal of this study is to investigate the effects of blood in the vitreous on retinal vascular function in rats. Methods. Intravitreal injections of autologous blood, plasma kallikrein (PK), bradykinin, and collagenase were performed in Sprague-Dawley and Long-Evans rats. Retinal vascular permeability was measured using vitreous fluorophotometry and Evans blue dye permeation. Leukostasis was measured by fluorescein isothiocyanate–coupled concanavalin A lectin and acridine orange labeling. Retinal hemorrhage was examined on retinal flatmounts. Primary cultures of bovine retinal pericytes were cultured in the presence of 25 nM PK for 24 hours. The pericyte-conditioned medium was collected and the collagen proteome was analyzed by tandem mass spectrometry. Results. Intravitreal injection of autologous blood induced retinal vascular permeability and retinal leukostasis, and these responses were ameliorated by PK inhibition. Intravitreal injections of exogenous PK induced retinal vascular permeability, leukostasis, and retinal hemorrhage. Proteomic analyses showed that PK increased collagen degradation in pericyte-conditioned medium and purified type IV collagen. Intravitreal injection of collagenase mimicked PK's effect on retinal hemorrhage. Conclusions. Intraocular hemorrhage increases retinal vascular permeability and leukostasis, and these responses are mediated, in part, via PK. Intravitreal injections of either PK or collagenase, but not bradykinin, induce retinal hemorrhage in rats. PK exerts collagenase-like activity that may contribute to blood–retinal barrier dysfunction. PMID:23299478

Liu, Jia; Clermont, Allen C.; Gao, Ben-Bo; Feener, Edward P.

2013-01-01

127

EPA Permeable Surface Research - Poster  

EPA Science Inventory

EPA recognizes permeable surfaces as an effective post-construction infiltration-based Best Management Practice to mitigate the adverse effects of stormwater runoff. The professional user community conceptually embraces permeable surfaces as a tool for making runoff more closely...

128

A drainage data-based calculation method for coalbed permeability  

NASA Astrophysics Data System (ADS)

This paper establishes a drainage data-based calculation method for coalbed permeability. The method combines material balance and production equations. We use a material balance equation to derive the average pressure of the coalbed in the production process. The dimensionless water production index is introduced into the production equation for the water production stage. In the subsequent stage, which uses both gas and water, the gas and water production ratio is introduced to eliminate the effect of flush-flow radius, skin factor, and other uncertain factors in the calculation of coalbed methane permeability. The relationship between permeability and surface cumulative liquid production can be described as a single-variable cubic equation by derivation. The trend shows that the permeability initially declines and then increases after ten wells in the southern Qinshui coalbed methane field. The results show an exponential relationship between permeability and cumulative water production. The relationship between permeability and cumulative gas production is represented by a linear curve and that between permeability and surface cumulative liquid production is represented by a cubic polynomial curve. The regression result of the permeability and surface cumulative liquid production agrees with the theoretical mathematical relationship.

Lai, Feng-peng; Li, Zhi-ping; Fu, Ying-kun; Yang, Zhi-hao

2013-12-01

129

Vascular Endothelial (VE)Cadherin: Only an Intercellular Glue?  

Microsoft Academic Search

Data collected during the past years indicate that AJ- and more specifically VE-cadherin play an important role in endothelial cell biology. VE-cadherin may transfer information intracellularly through interaction with a complex network of cytoskeletal and signaling molecules. Expression of VE-cadherin is required for the control of vascular permeability and vascular integrity. In addition, the molecule may exert a morphogenetic role

Elisabetta Dejana; Gianfranco Bazzoni; Maria Grazia Lampugnani

1999-01-01

130

Ve-ptp Modulates Vascular Integrity by Promoting Adherens Junction Maturation  

PubMed Central

Background Endothelial cell junctions control blood vessel permeability. Altered permeability can be associated with vascular fragility that leads to vessel weakness and haemorrhage formation. In vivo studies on the function of genes involved in the maintenance of vascular integrity are essential to better understand the molecular basis of diseases linked to permeability defects. Ve-ptp (Vascular Endothelial-Protein Tyrosine Phosphatase) is a transmembrane protein present at endothelial adherens junctions (AJs). Methodology/Principal Findings We investigated the role of Ve-ptp in AJ maturation/stability and in the modulation of endothelial permeability using zebrafish (Danio rerio). Whole-mount in situ hybridizations revealed zve-ptp expression exclusively in the developing vascular system. Generation of altered zve-ptp transcripts, induced separately by two different splicing morpholinos, resulted in permeability defects closely linked to vascular wall fragility. The ultrastructural analysis revealed a statistically significant reduction of junction complexes and the presence of immature AJs in zve-ptp morphants but not in control embryos. Conclusions/Significance Here we show the first in vivo evidence of a potentially critical role played by Ve-ptp in AJ maturation, an important event for permeability modulation and for the development of a functional vascular system. PMID:23251467

Carra, Silvia; Foglia, Efrem; Cermenati, Solei; Bresciani, Erica; Giampietro, Costanza; Lora Lamia, Carla; Dejana, Elisabetta

2012-01-01

131

Liquid-permeable electrode  

DOEpatents

Electrodes for use in an electrolytic cell, which are liquid-permeable and have low electrical resistance and high internal surface area are provided of a rigid, porous, carbonaceous matrix having activated carbon uniformly embedded throughout. The activated carbon may be catalyzed with platinum for improved electron transfer between electrode and electrolyte. Activated carbon is mixed with a powdered thermosetting phenolic resin and compacted to the desired shape in a heated mold to melt the resin and form the green electrode. The compact is then heated to a pyrolyzing temperature to carbonize and volatilize the resin, forming a rigid, porous structure. The permeable structure and high internal surface area are useful in electrolytic cells where it is necessary to continuously remove the products of the electrochemical reaction.

Folser, George R. (Lower Burrell, PA)

1980-01-01

132

Endothelial selectin blockade attenuates lung permeability of experimental acid aspiration  

Microsoft Academic Search

Background: A central role for the polymorphonuclear leukocyte (PMN) in experimental acid aspiration has been demonstrated by the observation that PMN depletion reduced pulmonary vascular permeability. This study investigates the role of recombinant soluble P-selectin glycoprotein ligand-immunoglobulin fusion protein (rPSGL-Ig), a P- and E-selectin antagonist in moderating acid aspiration lung injury. Methods: Tracheostomy tubes were placed in male C57BL\\/6 mice

Constantinos Kyriakides; William Austen; Yong Wang; Joanne Favuzza; Francis D Moore; Herbert B Hechtman

2000-01-01

133

Changes in mast cells and in permeability of mesenteric microvessels under the effect of immobilization and electrostimulation  

NASA Technical Reports Server (NTRS)

It was shown that a reduction in the amount of mast cells in the mesentery and an increase in their degranulation was accompanied by an increase in vascular permeability of rat mesentery. It is supposed that immobilization and electrostimulation causing degranulation of mast cells prompted histamine and serotonin release from them, thus increasing the permeability of the venular portion of the microvascular bed. Prophylactic use of esculamin preparation with P-vitaminic activity decreased mast cell degranulation, which apparently prolonged the release of histamine and serotonin from them and normalized vascular permeability.

Gorizontova, M. P.

1980-01-01

134

Branding of vascular surgery.  

PubMed

The Society for Vascular Surgery surveyed primary care physicians (PCPs) to understand how PCPs make referral decisions for their patients with peripheral vascular disease. Responses were received from 250 PCPs in 44 states. More than 80% of the respondents characterized their experiences with vascular surgeons as positive or very positive. PCPs perceive that vascular surgeons perform "invasive" procedures and refer patients with the most severe vascular disease to vascular surgeons but were more than twice as likely to refer patients to cardiologists, believing they are better able to perform minimally invasive procedures. Nevertheless, PCPs are receptive to the notion of increasing referrals to vascular surgeons. A successful branding campaign will require considerable education of referring physicians about the totality of traditional vascular and endovascular care increasingly provided by the contemporary vascular surgical practice and will be most effective at the local grassroots level. PMID:18388023

Perler, Bruce A

2008-03-01

135

Design and development of multilayer vascular graft  

NASA Astrophysics Data System (ADS)

Vascular graft is a widely-used medical device for the treatment of vascular diseases such as atherosclerosis and aneurysm as well as for the use of vascular access and pediatric shunt, which are major causes of mortality and morbidity in this world. Dysfunction of vascular grafts often occurs, particularly for grafts with diameter less than 6mm, and is associated with the design of graft materials. Mechanical strength, compliance, permeability, endothelialization and availability are issues of most concern for vascular graft materials. To address these issues, we have designed a biodegradable, compliant graft made of hybrid multilayer by combining an intimal equivalent, electrospun heparin-impregnated poly-epsilon-caprolactone nanofibers, with a medial equivalent, a crosslinked collagen-chitosan-based gel scaffold. The intimal equivalent is designed to build mechanical strength and stability suitable for in vivo grafting and to prevent thrombosis. The medial equivalent is designed to serve as a scaffold for the activity of the smooth muscle cells important for vascular healing and regeneration. Our results have shown that genipin is a biocompatible crosslinker to enhance the mechanical properties of collagen-chitosan based scaffolds, and the degradation time and the activity of smooth muscle cells in the scaffold can be modulated by the crosslinking degree. For vascular grafting and regeneration in vivo, an important design parameter of the hybrid multilayer is the interface adhesion between the intimal and medial equivalents. With diametrically opposite affinities to water, delamination of the two layers occurs. Physical or chemical modification techniques were thus used to enhance the adhesion. Microscopic examination and graft-relevant functional characterizations have been performed to evaluate these techniques. Results from characterization of microstructure and functional properties, including burst strength, compliance, water permeability and suture strength, showed that the multilayer graft possessed properties mimicking those of native vessels. Achieving these FDA-required functional properties is essential because they play critical roles in graft performances in vivo such as thrombus formation, occlusion, healing, and bleeding. In addition, cell studies and animal studies have been performed on the multilayer graft. Our results show that the multilayer graft support mimetic vascular culture of cells and the acellular graft serves as an artery equivalent in vivo to sustain the physiological conditions and promote appropriate cellular activity. In conclusion, the newly-developed hybrid multilayer graft provides a proper balance of biomechanical and biochemical properties and demonstrates the potential for the use of vascular tissue engineering and regeneration.

Madhavan, Krishna

136

Negative Refractive Index Metamaterials: Principles and Applications  

Microsoft Academic Search

Abstract – We review structures for ,microwave and optical range,containing 'left-handed' metamaterials ,– artificial composites with simultaneously negative effective permittivity and permeability which achieve negative values of refractive index. Attention has been given to the fundamentals of negative index materials, the main design strategies and proposed applications which includesubw avelength resonant cavities, sub- diffraction limited near-field lenses (superlenses) and ,phase

Zoran Jakši?; Nils Dalarsson; Milan Maksimovi?

2006-01-01

137

Glassy Dynamics, Cell Mechanics and Endothelial Permeability  

PubMed Central

A key feature of all inflammatory processes is disruption of the vascular endothelial barrier. Such disruption is initiated in part through active contraction of the cytoskeleton of the endothelial cell (EC). Because contractile forces are propagated from cell to cell across a great many cell-cell junctions, this contractile process is strongly cooperative and highly nonlocal. We show here that the characteristic length scale of propagation is modulated by agonists and antagonists that impact permeability of the endothelial barrier. In the presence of agonists including thrombin, histamine, and H202, force correlation length increases, whereas in the presence of antagonists including sphingosine-1-phosphate, hepatocyte growth factor, and the rho kinase inhibitor, Y27632, force correlation length decreases. Intercellular force chains and force clusters are also evident, both of which are reminiscent of soft glassy materials approaching a glass transition. PMID:23638866

Hardin, Corey; Rajendran, Kavitha; Manomohan, Greeshma; Tambe, Dhananjay T.; Butler, James P.; Fredberg, Jeffrey J.; Martinelli, Roberta; Carman, Christopher V.; Krishnan, Ramaswamy

2013-01-01

138

Glassy dynamics, cell mechanics, and endothelial permeability.  

PubMed

A key feature of all inflammatory processes is disruption of the vascular endothelial barrier. Such disruption is initiated in part through active contraction of the cytoskeleton of the endothelial cell (EC). Because contractile forces are propagated from cell to cell across a great many cell-cell junctions, this contractile process is strongly cooperative and highly nonlocal. We show here that the characteristic length scale of propagation is modulated by agonists and antagonists that impact permeability of the endothelial barrier. In the presence of agonists including thrombin, histamine, and H2O2, force correlation length increases, whereas in the presence of antagonists including sphingosine-1-phosphate, hepatocyte growth factor, and the rho kinase inhibitor, Y27632, force correlation length decreases. Intercellular force chains and force clusters are also evident, both of which are reminiscent of soft glassy materials approaching a glass transition. PMID:23638866

Hardin, Corey; Rajendran, Kavitha; Manomohan, Greeshma; Tambe, Dhananjay T; Butler, James P; Fredberg, Jeffrey J; Martinelli, Roberta; Carman, Christopher V; Krishnan, Ramaswamy

2013-10-24

139

Wave propagation in media having negative permittivity and permeability  

Microsoft Academic Search

Wave propagation in a double negative (DNG) medium, i.e., a medium having negative permittivity and negative permeability, is studied both analytically and numerically. The choices of the square root that leads to the index of refraction and the wave impedance in a DNG medium are determined by imposing analyticity in the complex frequency domain, and the corresponding wave properties associated

Richard W. Ziolkowski; Ehud Heyman

2001-01-01

140

Vascular Disease Foundation  

MedlinePLUS

... vascular eye openers ? TYPES of VASCULAR DISEASE Abdominal Aortic Aneurysm (AAA) Abdominal Aortic Aneurysms (AAA) are caused by progressive ... when a blood vessel bursts. Learn More Thoracic Aortic Aneurysm Aneurysms of the aorta can occur in the ...

141

A quantitative study of blood-brain barrier permeability ultrastructure in a new rat glioma model  

Microsoft Academic Search

Cerebral edema, a major complication of tumors in the brain, is the result of an alteration in the blood-brain barrier (B-BB). The vascular ultrastructural changes that underlie edema formation have been described in a variety of tumors. Interendothelial junction abnormalities, fenestrations, and large numbers of tubulo-vesicular profiles in the tumor vascular endothelium have been presumed to represent permeability routes that

P. A. Stewart; K. Hayakawa; E. Hayakawa; C. L. Farrell; R. F. Del Maestro

1985-01-01

142

Rocks of low permeability  

NASA Astrophysics Data System (ADS)

The 17th International Congress of the IAH (International Association of Hydrogeologists) will meet in Tucson, Ariz., January 7-10, 1985. The deadline for abstracts is March 1, 1984, and final papers are due October 15, 1984.The topic of the congress will be “Hydrogeology of Rocks of Low Permeability,” and speakers will include W. Back, J. F. Bredehoeft, G. de Marsily, J. E. Gale, P. Fritz, L. W. Gelhar, G. E. Grisak, C. W. Kreitler, M. R. Llamas, T. N. Narasimhan, I. Neretnieks, and E. P. Weeks. The congress will conclude with a panel discussion moderated by S. P. Neuman. Panelists include S. N. Davis, G. de Marsily, R. A. Freeze, P. A. Witherspoon, and I. Neretnieks.

143

Sphingolipids affect fibrinogen-induced caveolar transcytosis and cerebrovascular permeability.  

PubMed

Inflammation-induced vascular endothelial dysfunction can allow plasma proteins to cross the vascular wall, causing edema. Proteins may traverse the vascular wall through two main pathways, the paracellular and transcellular transport pathways. Paracellular transport involves changes in endothelial cell junction proteins, while transcellular transport involves caveolar transcytosis. Since both processes are associated with filamentous actin formation, the two pathways are interconnected. Therefore, it is difficult to differentiate the prevailing role of one or the other pathway during various pathologies causing an increase in vascular permeability. Using a newly developed dual-tracer probing method, we differentiated transcellular from paracellular transport during hyperfibrinogenemia (HFg), an increase in fibrinogen (Fg) content. Roles of cholesterol and sphingolipids in formation of functional caveolae were assessed using a cholesterol chelator, methyl-?-cyclodextrin, and the de novo sphingolipid synthesis inhibitor myriocin. Fg-induced formation of functional caveolae was defined by association and colocalization of Na+-K+-ATPase and plasmalemmal vesicle-associated protein-1 with use of Förster resonance energy transfer and total internal reflection fluorescence microscopy, respectively. HFg increased permeability of the endothelial cell layer mainly through the transcellular pathway. While M?CD blocked Fg-increased transcellular and paracellular transport, myriocin affected only transcellular transport. Less pial venular leakage of albumin was observed in myriocin-treated HFg mice. HFg induced greater formation of functional caveolae, as indicated by colocalization of Na+-K+-ATPase with plasmalemmal vesicle-associated protein-1 by Förster resonance energy transfer and total internal reflection fluorescence microscopy. Our results suggest that elevated blood levels of Fg alter cerebrovascular permeability mainly by affecting caveolae-mediated transcytosis through modulation of de novo sphingolipid synthesis. PMID:24829496

Muradashvili, Nino; Khundmiri, Syed Jalal; Tyagi, Reeta; Gartung, Allison; Dean, William L; Lee, Menq-Jer; Lominadze, David

2014-07-15

144

Retina vascular network recognition  

NASA Astrophysics Data System (ADS)

The analysis of morphological and structural modifications of the retina vascular network is an interesting investigation method in the study of diabetes and hypertension. Normally this analysis is carried out by qualitative evaluations, according to standardized criteria, though medical research attaches great importance to quantitative analysis of vessel color, shape and dimensions. The paper describes a system which automatically segments and recognizes the ocular fundus circulation and micro circulation network, and extracts a set of features related to morphometric aspects of vessels. For this class of images the classical segmentation methods seem weak. We propose a computer vision system in which segmentation and recognition phases are strictly connected. The system is hierarchically organized in four modules. Firstly the Image Enhancement Module (IEM) operates a set of custom image enhancements to remove blur and to prepare data for subsequent segmentation and recognition processes. Secondly the Papilla Border Analysis Module (PBAM) automatically recognizes number, position and local diameter of blood vessels departing from optical papilla. Then the Vessel Tracking Module (VTM) analyses vessels comparing the results of body and edge tracking and detects branches and crossings. Finally the Feature Extraction Module evaluates PBAM and VTM output data and extracts some numerical indexes. Used algorithms appear to be robust and have been successfully tested on various ocular fundus images.

Tascini, Guido; Passerini, Giorgio; Puliti, Paolo; Zingaretti, Primo

1993-09-01

145

Angiopoietin-2 Is Critical for Cytokine-Induced Vascular Leakage  

PubMed Central

Genetic experiments (loss-of-function and gain-of-function) have established the role of Angiopoietin/Tie ligand/receptor tyrosine kinase system as a regulator of vessel maturation and quiescence. Angiopoietin-2 (Ang-2) acts on Tie2-expressing resting endothelial cells as an antagonistic ligand to negatively interfere with the vessel stabilizing effects of constitutive Ang-1/Tie-2 signaling. Ang-2 thereby controls the vascular response to inflammation-inducing as well as angiogenesis-inducing cytokines. This study was aimed at assessing the role of Ang-2 as an autocrine (i.e. endothelial-derived) regulator of rapid vascular responses (within minutes) caused by permeability-inducing agents. Employing two independent in vivo assays to quantitatively assess vascular leakage (tracheal microsphere assay, 1–5 min and Miles assay, 20 min), the immediate vascular response to histamine, bradykinin and VEGF was analyzed in Ang-2-deficient (Ang-2?/?) mice. In comparison to the wild type control mice, the Ang2?/? mice demonstrated a significantly attenuated response. The Ang-2?/? phenotype was rescued by systemic administration (paracrine) of an adenovirus encoding Ang-2. Furthermore, cytokine-induced intracellular calcium influx was impaired in Ang-2?/? endothelioma cells, consistent with reduced phospholipase activation in vivo. Additionally, recombinant human Ang-2 (rhAng-2) alone was unable to induce vascular leakage. In summary, we report here in a definite genetic setting that Ang-2 is critical for multiple vascular permeability-inducing cytokines. PMID:23940579

Thomas, Markus; Laib, Anna M.; Loos, Elias K.; Fiedler, Ulrike; Augustin, Hellmut G.

2013-01-01

146

INDEX TO VOLUME 110 This index provides coverage for both the Initial Reports and Scientific Results  

E-print Network

Index is an index relating to significant findings and/or substantive discussions, not of species names bathymetry, 19b, 21b, 23b calcareous biogenic sediments, 17a­18a calcium concentrations, 22a carbonate carbon, 420b-421b permeability affected by, 335b-337b, 338b physical con

147

Vascular grading of angiogenesis: prognostic significance in breast cancer  

PubMed Central

The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11 years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers was moderately reproduced (? = 0.59). Vascular grade was significantly associated with axillary node involvement, tumour size, malignancy grade, oestrogen receptor status and histological type. In univariate analyses vascular grade significantly predicted recurrence free survival and overall survival for all patients (P< 0.0001), node-negative patients (P< 0.0001) and node-positive patients (P< 0.0001). Cox multivariate regression analysis showed that vascular grading contributed with independent prognostic value in all patients (P< 0.0001). A prognostic index including the vascular grade had clinical impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer. © 2000 Cancer Research Campaign PMID:10646886

Hansen, S; Grabau, D A; S?rensen, F B; Bak, M; Vach, W; Rose, C

2000-01-01

148

Effect of various pharmacological agents on prostaglandin induced increases in microvascular permeability.  

PubMed

The anti-histamines, pyrilamine and chlorpheniramine, the serotonin antagonist, methysergide, the beta-adrenolytic, phenoxybenzamine and the anti-cholinergic, atropine, antagonized the prostaglandin E1 induced increases in vascular permeability. None of the non-steroidal anti-inflammatory agents acted as antagonists at these doses. PMID:1197936

Panagides, J; Tolman, E L

1975-11-01

149

Microvascular permeability in induced astrocytomas and peritumor neuropil of rat brain  

Microsoft Academic Search

Brain tumors, benign and malignant, are characteristically more permeable to various types of tracer molecules than the neuropil in which they are embedded. Impermeability of brain neuropil capillaries is imparted by the blood-brain barrier, the anatomic basis of which is the network of interendothelial zonulae occludentes that seal capillary endothelial cells. To explore both the vascular elements of brain neoplasms

R. R. Shiversi; C. L. Edmonds; R. F. Maestro

1984-01-01

150

Gas permeability of carbon aerogels  

SciTech Connect

Carbon aerogels are synthesized via the aqueous polycondensation of resorcinol with formaldehyde, followed by supercritical drying and subsequent pyrolysis at 1050 [degree]C. As a result of their interconnected porosity, ultrafine cell/pore size, and high surface area, carbon aerogels have many potential applications such as supercapacitors, battery electrodes, catalyst supports, and gas filters. The performance of carbon aerogels in the latter two applications depends on the permeability or gas flow conductance in these materials. By measuring the pressure differential across a thin specimen and the nitrogen gas flow rate in the viscous regime, the permeability of carbon aerogels was calculated from equations based upon Darcy's law. Our measurements show that carbon aerogels have permeabilities on the order of 10[sup [minus]12] to 10[sup [minus]10] cm[sup 2] over the density range from 0.05--0.44 g/cm[sup 3]. Like many other aerogel properties, the permeability of carbon aerogels follows a power law relationship with density, reflecting differences in the average mesopore size. Comparing the results from this study with the permeability of silica aerogels reported by other workers, we found that the permeability of aerogels is governed by a simple universal flow equation. This paper discusses the relationship between permeability, pore size, and density in carbon aerogels.

Kong, F.; LeMay, J.D.; Hulsey, S.S.; Alviso, C.T.; Pekala, R.W. (Chemistry and Materials Science Department, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1993-12-01

151

Platelets mediate increased endothelium permeability in dengue through NLRP3-inflammasome activation  

PubMed Central

Dengue is the most frequent hemorrhagic viral disease and re-emergent infection in the world. Although thrombocytopenia is characteristically observed in mild and severe forms of dengue, the role of platelet activation in dengue pathogenesis has not been fully elucidated. We hypothesize that platelets have major roles in inflammatory amplification and increased vascular permeability during severe forms of dengue. Here we investigate interleukin (IL)-1? synthesis, processing, and secretion in platelets during dengue virus (DV) infection and potential contribution of these events to endothelial permeability during infection. We observed increased expression of IL-1? in platelets and platelet-derived microparticles from patients with dengue or after platelet exposure to DV in vitro. We demonstrated that DV infection leads to assembly of nucleotide-binding domain leucine rich repeat containing protein (NLRP3) inflammasomes, activation of caspase-1, and caspase-1–dependent IL-1? secretion. Our findings also indicate that platelet-derived IL-1? is chiefly released in microparticles through mechanisms dependent on mitochondrial reactive oxygen species–triggered NLRP3 inflammasomes. Inflammasome activation and platelet shedding of IL-1?–rich microparticles correlated with signs of increased vascular permeability. Moreover, microparticles from DV-stimulated platelets induced enhanced permeability in vitro in an IL-1–dependent manner. Our findings provide new evidence that platelets contribute to increased vascular permeability in DV infection by inflammasome-dependent release of IL-1?. PMID:24009231

Hottz, Eugenio D.; Lopes, Juliana F.; Freitas, Carla; Valls-de-Souza, Rogerio; Oliveira, Marcus F.; Bozza, Marcelo T.; Da Poian, Andrea T.; Weyrich, Andrew S.; Zimmerman, Guy A.

2013-01-01

152

Loss of the Endothelial Glycocalyx Links Albuminuria and Vascular Dysfunction  

PubMed Central

Patients with albuminuria and CKD frequently have vascular dysfunction but the underlying mechanisms remain unclear. Because the endothelial surface layer, a meshwork of surface-bound and loosely adherent glycosaminoglycans and proteoglycans, modulates vascular function, its loss could contribute to both renal and systemic vascular dysfunction in proteinuric CKD. Using Munich-Wistar-Fromter (MWF) rats as a model of spontaneous albuminuric CKD, multiphoton fluorescence imaging and single-vessel physiology measurements revealed that old MWF rats exhibited widespread loss of the endothelial surface layer in parallel with defects in microvascular permeability to both water and albumin, in both continuous mesenteric microvessels and fenestrated glomerular microvessels. In contrast to young MWF rats, enzymatic disruption of the endothelial surface layer in old MWF rats resulted in neither additional loss of the layer nor additional changes in permeability. Intravenous injection of wheat germ agglutinin lectin and its adsorption onto the endothelial surface layer significantly improved glomerular albumin permeability. Taken together, these results suggest that widespread loss of the endothelial surface layer links albuminuric kidney disease with systemic vascular dysfunction, providing a potential therapeutic target for proteinuric kidney disease. PMID:22797190

Ferguson, Joanne K.; Burford, James L.; Gevorgyan, Haykanush; Nakano, Daisuke; Harper, Steven J.; Bates, David O.; Peti-Peterdi, Janos

2012-01-01

153

International Plant Names Index (IPNI)  

NSDL National Science Digital Library

A collaborative initiative of The Royal Botanic Gardens (Kew), The Harvard University Herbaria, and the Australian National Herbarium, the International Plant Names Index (IPNI) is a comprehensive, literature-based database of the scientific names and associated basic bibliographical details of all vascular (seed) plants. A dynamic resource intended for use by all members of the botanical community, IPNI currently includes more than a million records from Index Kewensis, the Gray Index (originally the Gray Herbarium Card Index), and the Australian Plant Names Index; additional records are added periodically. IPNI is accessible in a searchable format: by Plant name (Family, Genus, Species), Author (forename, surname, country), Publication (title or abbreviation), or Collector (or Collector Team Name). Returns include full scientific name and primary source references for each matching case in the database.

1999-01-01

154

Determination of renal vascular resistance in dogs with diabetes mellitus and hyperadrenocorticism  

Microsoft Academic Search

In dogs, diabetes mellitus and hyperadrenocorticism are causes of hypertension associated with increases in vascular peripheral resistance. In human patients, the renal resistive index (ri) and pulsatility index (pi) are related to hypertension and diabetes and are used as indicators of disease severity. In this study the renal vascular resistance was measured in 12 dogs with hyperadrenocorticism, three with diabetes

R. Novellas; R. Ruiz de Gopegui; Y. Espada

2008-01-01

155

Low-Dose Dopamine Agonist Administration Blocks Vascular Endothelial Growth Factor (VEGF)-Mediated Vascular Hyperpermeability without Altering VEGF Receptor 2Dependent Luteal Angiogenesis in a Rat Ovarian Hyperstimulation Model  

Microsoft Academic Search

No specific treatment is available for ovarian hyperstimula- tion syndrome (OHSS), the most important complication in infertile women treated with gonadotropins. OHSS is caused by increased vascular permeability (VP) through ovarian hy- persecretion of vascular endothelial growth factor (VEGF)- activating VEGF receptor 2 (VEGFR-2). We previously dem- onstrated in an OHSS rodent model that increased VP was prevented by inactivating

Raul Gomez; Miguel Gonzalez-Izquierdo; Ralf C. Zimmermann; Edurne Novella-Maestre; Isabel Alonso-Muriel; Jose Sanchez-Criado; Jose Remohi; Carlos Simon; Antonio Pellicer

2006-01-01

156

Opening the flood-gates: how neutrophil-endothelial interactions regulate permeability  

PubMed Central

Many diseases have an inflammatory component, where neutrophil interactions with the vascular endothelium lead to barrier dysfunction and increased permeability. Neutrophils increase permeability through secreted products like the chemokines CXCL1, 2, 3 and 8, through adhesion-dependent processes like ?2 integrins interacting with endothelial ICAM-1, and combinations, where ?2 integrin engagement leads to degranulation and secretion of heparin-binding protein (HBP), which in turn increases permeability. Some neutrophil products like arachidonic acid or leukotriene (LT)A4 are further processed by endothelial enzymes through transcellular metabolism before the resulting products thromboxane A2, LTB4 or LTC4 can activate their cognate receptors. Neutrophils also generate reactive oxygen species that induce vascular leakage. This review focuses on the mechanisms of neutrophil-mediated leakage. PMID:19783480

DiStasi, Matthew R.; Ley, Klaus

2009-01-01

157

VEGFR2 and Src Kinase Inhibitors Suppress Andes Virus-Induced Endothelial Cell Permeability ?  

PubMed Central

Hantaviruses predominantly infect human endothelial cells and, in the absence of cell lysis, cause two diseases resulting from increased vascular permeability. Andes virus (ANDV) causes a highly lethal acute pulmonary edema termed hantavirus pulmonary syndrome (HPS). ANDV infection enhances the permeability of endothelial cells in response to vascular endothelial growth factor (VEGF) by increasing signaling responses directed by the VEGFR2-Src-VE-cadherin pathway, which directs adherens junction (AJ) disassembly. Here we demonstrate that inhibiting pathway-specific VEGFR2 and Src family kinases (SFKs) blocks ANDV-induced endothelial cell permeability. Small interfering RNA (siRNA) knockdown of Src within ANDV-infected endothelial cells resulted in an ?70% decrease in endothelial cell permeability compared to that for siRNA controls. This finding suggested that existing FDA-approved small-molecule kinase inhibitors might similarly block ANDV-induced permeability. The VEGFR2 kinase inhibitor pazopanib as well as SFK inhibitors dasatinib, PP1, bosutinib, and Src inhibitor 1 dramatically inhibited ANDV-induced endothelial cell permeability. Consistent with their kinase-inhibitory concentrations, dasatinib, PP1, and pazopanib inhibited ANDV-induced permeability at 1, 10, and 100 nanomolar 50% inhibitory concentrations (IC50s), respectively. We further demonstrated that dasatinib and pazopanib blocked VE-cadherin dissociation from the AJs of ANDV-infected endothelial cells by >90%. These findings indicate that VEGFR2 and Src kinases are potential targets for therapeutically reducing ANDV-induced endothelial cell permeability and, as a result, capillary permeability during HPS. Since the functions of VEGFR2 and SFK inhibitors are already well defined and FDA approved for clinical use, these findings rationalize their therapeutic evaluation for efficacy in reducing HPS disease. Endothelial cell barrier functions are disrupted by a number of viruses that cause hemorrhagic, edematous, or neurologic disease, and as a result, our findings suggest that VEGFR2 and SFK inhibitors should be considered for regulating endothelial cell barrier functions altered by additional viral pathogens. PMID:21177802

Gorbunova, Elena E.; Gavrilovskaya, Irina N.; Pepini, Timothy; Mackow, Erich R.

2011-01-01

158

Geothermal Permeability Enhancement - Final Report  

SciTech Connect

The overall objective is to apply known permeability enhancement techniques to reduce the number of wells needed and demonstrate the applicability of the techniques to other undeveloped or under-developed fields. The Enhanced Geothermal System (EGS) concept presented in this project enhances energy extraction from reduced permeability zones in the super-heated, vapor-dominated Aidlin Field of the The Geysers geothermal reservoir. Numerous geothermal reservoirs worldwide, over a wide temperature range, contain zones of low permeability which limit the development potential and the efficient recovery of heat from these reservoirs. Low permeability results from poorly connected fractures or the lack of fractures. The Enhanced Geothermal System concept presented here expands these technologies by applying and evaluating them in a systematic, integrated program.

Joe Beall; Mark Walters

2009-06-30

159

Permeability of cork to gases.  

PubMed

The permeability of gases through uncompressed cork was investigated. More than 100 samples were assessed from different plank qualities to provide a picture of the permeability distribution. A novel technique based on a mass spectrometer leak detector was used to directly measure the helium flow through the central area of small disks 10 mm in diameter and 2 mm thick. The permeability for nitrogen, oxygen, and other gases was measured by the pressure rise technique. Boiled and nonboiled cork samples from different sections were evaluated. An asymmetric frequency distribution ranging 3 orders of magnitude (roughly from 1 to 1000 ?mol/(cm·atm·day)) for selected samples without macroscopic defects was found, having a peak below 100 ?mol/(cm·atm·day). Correlation was found between density and permeability: higher density samples tend to show lower permeability. However, boiled cork showed a mean lower permeability despite having a lower density. The transport mechanism of gases through cork was also examined. Calculations suggest that gases permeate uncompressed cork mainly through small channels between cells under a molecular flow regime. The diameter of such channels was estimated to be in the range of 100 nm, in agreement with the plasmodesmata size in the cork cell walls. PMID:21434693

Faria, David P; Fonseca, Ana L; Pereira, Helen; Teodoro, Orlando M N D

2011-04-27

160

Permeability theory and Palace Athena.  

PubMed

Permeability theory suggests that safety in environments depends on how far and how easily one can perceive or move through environments. Parts of environments that limit perception or retard locomotion elicit impressions of being enclosed, so properties of environments that influence perceived enclosure are important in permeability theory. One prediction of permeability theory is that the more permeable the boundary, the less enclosed the region within that boundary will seem to be. Another prediction is that boundary depth will have little influence on perceived enclosure. These predictions were tested in the venue of Greek temples. 30 participants were tested (14 men, 16 women; M age = 40 yr.), who rated perceived enclosure for 18 stimuli. The stimuli were constructed using a virtual scene from the Tholos in Delphi with the positions of the columns forming the boundaries. The boundaries were designed to have different levels of permeability and depth. Data were analyzed in terms of effect sizes and focused comparisons. Results indicated that perceived enclosure was most strongly influenced by the visual permeability of the boundary, while depth of boundary had a much smaller effect on perceived enclosure. PMID:24175455

Stamps, Arthur E

2013-06-01

161

Vascular Plant Image Gallery  

NSDL National Science Digital Library

Texas A&M University's Bioinformatics Working Group offers this no-nonsense botany teaching resource. Vascular plants are arranged alphabetically by family from Acanthaceae to Zygophyllaceae and users simply click for the images. Brief descriptions are provided (which may indicate the popular name of the plant). The site is searchable. Familiarity with vascular plant taxonomic nomenclature is assumed.

Manhart, James R.

162

Vascular cell senescence and vascular aging  

Microsoft Academic Search

Vascular cells have a finite lifespan when cultured in vitro and eventually enter an irreversible growth arrest called “cellular senescence”. A number of genetic animal models carrying targeted disruption of the genes that confer the protection against senescence in vitro have been reported to exhibit the phenotypes of premature aging. Similar mutations have been found in the patients with premature

Tohru Minamino; Hideyuki Miyauchi; Toshihiko Yoshida; Kaoru Tateno; Takeshige Kunieda; Issei Komuro

2004-01-01

163

Immigration Index  

NSDL National Science Digital Library

Striving to become the "immigration resource directory on the net," the Immigration Index is a newly launched Website dedicated to news and information about immigration worldwide. Along with breaking headlines from a variety of news sources about immigration-related issues such as asylum, migration, trafficking and women, and much more, the site contains a fully annotated collection of links to immigration materials all around the World Wide Web. Only a month old, some of the categories in the Index's hierarchy still need some filling in. In time, however, the Immigration Index promises to become an invaluable resource for interested parties.

164

Vascular Access in Children  

SciTech Connect

Establishment of stable vascular access is one of the essential and most challenging procedures in a pediatric hospital. Many clinical specialties provide vascular service in a pediatric hospital. At the top of the 'expert procedural pyramid' is the pediatric interventional radiologist, who is best suited and trained to deliver this service. Growing awareness regarding the safety and high success rate of vascular access using image guidance has led to increased demand from clinicians to provide around-the-clock vascular access service by pediatric interventional radiologists. Hence, the success of a vascular access program, with the pediatric interventional radiologist as the key provider, is challenging, and a coordinated multidisciplinary team effort is essential for success. However, there are few dedicated pediatric interventional radiologists across the globe, and also only a couple of training programs exist for pediatric interventions. This article gives an overview of the technical aspects of pediatric vascular access and provides useful tips for obtaining vascular access in children safely and successfully using image guidance.

Krishnamurthy, Ganesh, E-mail: krishnamurthy@email.chop.edu; Keller, Marc S. [Children's Hospital of Philadelphia, Department of Radiology (United States)

2011-02-15

165

Infrared magnetic and negative-index metamaterials  

Microsoft Academic Search

Negative-index materials have attracted much attention because of their many unconventional optical properties such as negative refractive angle, phase back propagation, reversed Doppler effect and reversed Cherenkov radiation. Recently, much progress has been made in this research area such as demonstrations of negative permeability \\

Shuang Zhang

2005-01-01

166

Thromboxane A{sub 2} increases endothelial permeability through upregulation of interleukin-8  

SciTech Connect

Thromboxane A{sub 2} (TXA{sub 2}), a major prostanoid formed from prostaglandin H{sub 2} by thromboxane synthase, is involved in the pathogenesis of a variety of vascular diseases. In this study, we report that TXA{sub 2} mimetic U46619 significantly increases the endothelial permeability both in vitro and in vivo. U46619 enhanced the expression and secretion of interleukin-8 (IL-8), a major inducer of vascular permeability, in endothelial cells. Promoter analysis showed that the U46619-induced expression of IL-8 was mainly regulated by nuclear factor-{kappa}B (NF-{kappa}B). U46619 induced the activation of NF-{kappa}B through I{kappa}B kinase (IKK) activation, I{kappa}B phosphorylation and NF-{kappa}B nuclear translocation. Furthermore, the inhibition of IL-8 or blockade of the IL-8 receptor attenuated the U46619-induced endothelial cell permeability by modulating the cell-cell junctions. Overall, these results suggest that U46619 promotes vascular permeability through the production of IL-8 via NF-{kappa}B activation in endothelial cells.

Kim, Su-Ryun [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of) [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of); Medical Research Center for Ischemic Tissue Regeneration and School of Medicine, Pusan National University, Yangsan 626-870 (Korea, Republic of); Bae, Soo-Kyung [Medical Research Center for Ischemic Tissue Regeneration and School of Medicine, Pusan National University, Yangsan 626-870 (Korea, Republic of)] [Medical Research Center for Ischemic Tissue Regeneration and School of Medicine, Pusan National University, Yangsan 626-870 (Korea, Republic of); Park, Hyun-Joo; Kim, Mi-Kyoung [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of)] [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of); Kim, Koanhoi [Medical Research Center for Ischemic Tissue Regeneration and School of Medicine, Pusan National University, Yangsan 626-870 (Korea, Republic of)] [Medical Research Center for Ischemic Tissue Regeneration and School of Medicine, Pusan National University, Yangsan 626-870 (Korea, Republic of); Park, Shi-Young [Department of Molecular Biology, Pusan National University, Pusan 609-735 (Korea, Republic of)] [Department of Molecular Biology, Pusan National University, Pusan 609-735 (Korea, Republic of); Jang, Hye-Ock; Yun, Il [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of)] [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of); Kim, Yung-Jin; Yoo, Mi-Ae [Department of Molecular Biology, Pusan National University, Pusan 609-735 (Korea, Republic of)] [Department of Molecular Biology, Pusan National University, Pusan 609-735 (Korea, Republic of); Bae, Moon-Kyoung, E-mail: mkbae@pusan.ac.kr [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of)] [School of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Yangsan 626-870 (Korea, Republic of)

2010-07-02

167

Heart and vascular services  

MedlinePLUS

... heart or blood vessel problems. This may include: Heart transplant Insertion of pacemakers or defibrillators Open and minimally invasive coronary artery bypass surgery Repair or replacement of ... valves Surgical treatment of congenital heart defects Vascular ...

168

Uterine Vascular Lesions  

PubMed Central

Vascular lesions of the uterus are rare; most reported in the literature are arteriovenous malformations (AVMs). Uterine AVMs can be congenital or acquired. In recent years, there has been an increasing number of reports of acquired vascular lesions of the uterus following pregnancy, abortion, cesarean delivery, and curettage. It can be seen from these reports that there is confusion concerning the terminology of uterine vascular lesions. There is also a lack of diagnostic criteria and management guidelines, which has led to an increased number of unnecessary invasive procedures (eg, angiography, uterine artery embolization, hysterectomy for abnormal vaginal bleeding). This article familiarizes readers with various vascular lesions of the uterus and their management. PMID:24340126

Vijayakumar, Abhishek; Srinivas, Amruthashree; Chandrashekar, Babitha Moogali; Vijayakumar, Avinash

2013-01-01

169

Diversity in vascular surgery.  

PubMed

A growing body of literature in vascular surgery demonstrates disparities in the type of health care that racial/ethnic minorities receive in the United States. Numerous recommendations, including those of the Institute of Medicine, have been set forth, which identify increasing the number of minority health professionals as a key strategy to eliminating health disparities. The purpose of this study is to compare the racial/ethnic distribution of the Society for Vascular Surgery (SVS) membership, the SVS leadership, vascular surgery trainees, and medical students. The results demonstrate that the racial/ethnic distribution of the SVS membership reflects a considerable lack of diversity with a paucity of diversity among the SVS leadership. An increasing rate of racial/ethnic diversity among vascular surgery trainees may indicate that the SVS will see an improvement in diversity in the future. PMID:23182481

Woo, Karen; Kalata, Emily A; Hingorani, Anil P

2012-12-01

170

Congenital Vascular Malformation  

MedlinePLUS

... indications: persistent pain, ulceration, bleeding, blood clots, obstruction of major vessels, causing progressive limb asymmetry by overgrowth, and for cosmetic indications or because the vascular mass is cumbersome and leads to a ...

171

Women and Vascular Disease  

MedlinePLUS

... Radiology Minimally Invasive Treatments Snapshots Multimedia Multimedia Archive Women and Vascular Disease Early Warning Symptom for the #1 Killer of Women Is Under-recognized Heart disease is the #1 ...

172

What Is Vascular Disease?  

MedlinePLUS

... Americans each year. @ 2014 Vascular Cures is a tax-exempt, nonprofit organization tax ID#: 94-2825216 as described in the Section ... 3) of the Internal Revenue Code. Donations are tax deductible. 555 Price Ave., Suite 180, Redwood City, ...

173

Assessing vascular endothelial function using frequency and rank order statistics  

NASA Astrophysics Data System (ADS)

Using frequency and rank order statistics (FROS), this study analyzed the fluctuations in arterial waveform amplitudes recorded from an air pressure sensing system before and after reactive hyperemia (RH) induction by temporary blood flow occlusion to evaluate the vascular endothelial function of aged and diabetic subjects. The modified probability-weighted distance (PWD) calculated from the FROS was compared with the dilatation index (DI) to evaluate its validity and sensitivity in the assessment of vascular endothelial function. The results showed that the PWD can provide a quantitative determination of the structural changes in the arterial pressure signals associated with regulation of vascular tone and blood pressure by intact vascular endothelium after the application of occlusion stress. Our study suggests that the use of FROS is a reliable noninvasive approach to the assessment of vascular endothelial degeneration in aging and diabetes.

Wu, Hsien-Tsai; Hsu, Po-Chun; Sun, Cheuk-Kwan; Liu, An-Bang; Lin, Zong-Lin; Tang, Chieh-Ju; Lo, Men-Tzung

2013-08-01

174

Vascular access for hemodialysis  

Microsoft Academic Search

Establishing and maintaining adequate vascular access is essential to providing an appropriate dialysis dose in patients with end-stage renal disease. Complications related to vascular access have a significant role in dialysis-related morbidity and mortality. The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K\\/DOQI) clinical practice guideline for dialysis access was last updated in 2000 and provides a framework for

Rick Hayashi; Edmund Huang; Allen R Nissenson

2006-01-01

175

Diagnosis of Vascular Dementia  

Microsoft Academic Search

Vascular dementia (VaD) is diagnosed when a syndrome of dementia or cognitive impairment is found concurrently with evidence\\u000a of cerebrovascular disease (CVD). There are no pathognomonic neuropathological lesions of vascular dementia—no individual\\u000a pathological feature has any value in relation to an individual case—because subjects with and without dementia can have similar\\u000a changes (1). This means that VaD is a theoretical

José G. Merino; Vladimir Hachinski

176

Slit2-Robo4 Receptor Responses Inhibit ANDV Directed Permeability of Human Lung Microvascular Endothelial Cells  

PubMed Central

Hantaviruses nonlytically infect human endothelial cells (ECs) and cause edematous and hemorrhagic diseases. Andes virus (ANDV) causes hantavirus pulmonary syndrome (HPS), and Hantaan virus (HTNV) causes hemorrhagic fever with renal syndrome (HFRS). Hantaviruses enhance vascular endothelial growth factor directed EC permeability resulting in the disassembly of inter-endothelial cell adherens junctions (AJs). Recent studies demonstrate that Slit2 binding to Robo1/Robo4 receptors on ECs has opposing effects on AJ disassembly and vascular fluid barrier functions. Here we demonstrate that Slit2 inhibits ANDV and HTNV induced permeability and AJ disassembly of pulmonary microvascular ECs (PMECs) by interactions with Robo4. In contrast, Slit2 had no effect on the permeability of ANDV infected human umbilical vein ECs (HUVECs). Analysis of Robo1/Robo4 expression determined that PMECs express Robo4, but not Robo1, while HUVECs expressed both Robo4 and Robo1 receptors. SiRNA knockdown of Robo4 in PMECs prevented Slit2 inhibition of ANDV induced permeability demonstrating that Robo4 receptors determine PMEC responsiveness to Slit2. Collectively, this data demonstrates a selective role for Slit2/Robo4 responses within PMECs that inhibits ANDV induced permeability and AJ disassembly. These findings suggest Slit2s utility as a potential HPS therapeutic that stabilizes the pulmonary endothelium and antagonizes ANDV induced pulmonary edema. PMID:23702092

Gorbunova, Elena E.; Gavrilovskaya, Irina N.; Mackow, Erich R.

2013-01-01

177

Slit2-Robo4 receptor responses inhibit ANDV directed permeability of human lung microvascular endothelial cells.  

PubMed

Hantaviruses nonlytically infect human endothelial cells (ECs) and cause edematous and hemorrhagic diseases. Andes virus (ANDV) causes hantavirus pulmonary syndrome (HPS), and Hantaan virus (HTNV) causes hemorrhagic fever with renal syndrome (HFRS). Hantaviruses enhance vascular endothelial growth factor directed EC permeability resulting in the disassembly of inter-endothelial cell adherens junctions (AJs). Recent studies demonstrate that Slit2 binding to Robo1/Robo4 receptors on ECs has opposing effects on AJ disassembly and vascular fluid barrier functions. Here we demonstrate that Slit2 inhibits ANDV and HTNV induced permeability and AJ disassembly of pulmonary microvascular ECs (PMECs) by interactions with Robo4. In contrast, Slit2 had no effect on the permeability of ANDV infected human umbilical vein ECs (HUVECs). Analysis of Robo1/Robo4 expression determined that PMECs express Robo4, but not Robo1, while HUVECs expressed both Robo4 and Robo1 receptors. SiRNA knockdown of Robo4 in PMECs prevented Slit2 inhibition of ANDV induced permeability demonstrating that Robo4 receptors determine PMEC responsiveness to Slit2. Collectively, this data demonstrates a selective role for Slit2/Robo4 responses within PMECs that inhibits ANDV induced permeability and AJ disassembly. These findings suggest Slit2s utility as a potential HPS therapeutic that stabilizes the pulmonary endothelium and antagonizes ANDV induced pulmonary edema. PMID:23702092

Gorbunova, Elena E; Gavrilovskaya, Irina N; Mackow, Erich R

2013-08-01

178

Vascular expression of glucose transporter in experimental brain neoplasms.  

PubMed Central

Vascular abnormalities in brain neoplasms are important to tumor biology and therapy. Glucose transporter (GLUT1) expression is a differentiated property of normal cerebral microvessels typically associated with expression of the blood-brain barrier. We investigated the relationship of GLUT1 expression to other vascular characteristics in F98, 9L, and C6 gliomas and Walker 256 carcinomas implanted into adult rat brains. The percentages of microvessels with immunohistochemically detectable GLUT1 were 95.5 +/- 3.9 in F98, 60.9 +/- 3.9 in 9L, 45.4 +/- 5.6 in C6, and 1.2 +/- 0.3 in Walker 256 (mean +/- SEM). The percentage of GLUT1-positive vessels in F98 was not statistically different from that in normal brain. GLUT1 expression was not dependent on restricted permeability as all tumors were highly permeable to Evans blue. GLUT1 expression was unrelated to vascular density, vascular morphology, and parenchymal GFAP expression. The expression of GLUT1, a marker of cerebral endothelial differentiation, is a newly described property of glial tumor vessels that may have diagnostic and prognostic significance. Images Figure 2 Figure 1 Figure 4 Figure 6 PMID:1739134

Guerin, C.; Laterra, J.; Drewes, L. R.; Brem, H.; Goldstein, G. W.

1992-01-01

179

Permeable Pavement Research ? Edison, NJ  

EPA Science Inventory

This presentation gives the rationale behind NRMRL?s decision to construct and test a permeable surface parking lot the Edison Environmental Center. It also describes the monitoring program and gives preliminary results. The presentation is being given at the request of the New...

180

Review of permeable pavement systems  

Microsoft Academic Search

The purpose of this review paper is to summarise the wide-range but diffuse literature on predominantly permeable pavement systems (PPS), highlight current trends in research and industry, and to recommend future areas of research and development. The development of PPS as an integral part of sustainable drainage systems is reviewed in the context of traditional and modern urban drainage. Particular

Miklas Scholz; Piotr Grabowiecki

2007-01-01

181

The Permeability of Porous Materials  

Microsoft Academic Search

The permeability, of a porous material to water is a function of the geometry of the boundary between the solid component and the pore space. Expressions of the Kozeny type purporting to represent this function are based upon the particle size or specific surface of the solids, and whilst, for engineering practice, they have given satisfaction for saturated sands, they

E. C. Childs; N. Collis-George

1950-01-01

182

Diffusion and Osmosis Selectively Permeable  

E-print Network

Diffusion and Osmosis #12;Selectively Permeable Some substances can pass through the membrane getting rid of waste products. #12;Diffusion Molecules move from an area of higher concentration to an area of lower concentration What causes diffusion? ­ Random motion of molecules 2 3 1 4 Water

Rose, Michael R.

183

The permeability of oral leukoplakia.  

PubMed

The significant increase in oral cancer mortality necessitates further research on the mechanisms of tumorigenesis. It was the aim of this study to compare the permeability, lipid composition and histopathological characteristics of oral leukoplakia with non-lesional specimens of the same region in 30 cases as well as 11 specimens originating from healthy control buccal mucosa. The permeability (Kp) of tissue biopsies to tritiated nitrosonornicotine was determined in a continuous through-flow perfusion system, lipids were extracted and identified by thin-layer chromatography, and thickness of epithelium and keratin layer assessed by histopathological methods. Results of the measurements showed that the permeability to the tobacco carcinogen, nitrosonornicotine for leukoplakic tissue was higher than for normal control buccal specimens. Non-lesional areas of buccal mucosa, adjacent to leukoplakias, showed hyperplasia and significantly higher permeability values than both leukoplakic and normal buccal control mucosa. The lipid content of the non-lesional sites was intermediate between the increased values of the leukoplakic lesion and of normal control mucosa. The data strongly suggest that the presence of tobacco in the oral cavity may bring about generalized changes even in regions that do not show leukoplakia. PMID:12887396

Bánóczy, Jolán; Squier, Christopher A; Kremer, Mary; Wertz, Philip W; Kövesi, György; Szende, Béla; Dombi, Csaba

2003-08-01

184

Novel microwave devices using tunable negative index metamaterials and ferrites  

Microsoft Academic Search

Next generation microwave devices require to be multifunctional for efficient, cost effective operation in light weight, low volume structures. A miniature tunable negative index metamaterial phase shifter and an ultra wideband phased array antenna have been designed using ferrite materials. Negative permeability ferrite material in combination with negative permittivity of plasmonic wires produces a tunable negative refractive index metamaterial (TNIM).

Patanjali V. Parimi; Peng Peyton; Joseph M. Kunze; Carmine Vittoria; Vincent G. Harris

2009-01-01

185

Radiation Effects on the Cytoskeleton of Endothelial Cells and Endothelial Monolayer Permeability  

SciTech Connect

Purpose: To investigate the effects of radiation on the endothelial cytoskeleton and endothelial monolayer permeability and to evaluate associated signaling pathways, which could reveal potential mechanisms of known vascular effects of radiation. Methods and Materials: Cultured endothelial cells were X-ray irradiated, and actin filaments, microtubules, intermediate filaments, and vascular endothelial (VE)-cadherin junctions were examined by immunofluorescence. Permeability was determined by the passage of fluorescent dextran through cell monolayers. Signal transduction pathways were analyzed using RhoA, Rho kinase, and stress-activated protein kinase-p38 (SAPK2/p38) inhibitors by guanosine triphosphate-RhoA activation assay and transfection with RhoAT19N. The levels of junction protein expression and phosphorylation of myosin light chain and SAPK2/p38 were assessed by Western blotting. The radiation effects on cell death were verified by clonogenic assays. Results: Radiation induced rapid and persistent actin stress fiber formation and redistribution of VE-cadherin junctions in microvascular, but not umbilical vein endothelial cells, and microtubules and intermediate filaments remained unaffected. Radiation also caused a rapid and persistent increase in microvascular permeability. RhoA-guanosine triphosphatase and Rho kinase were activated by radiation and caused phosphorylation of downstream myosin light chain and the observed cytoskeletal and permeability changes. SAPK2/p38 was activated by radiation but did not influence either the cytoskeleton or permeability. Conclusion: This study is the first to show rapid activation of the RhoA/Rho kinase by radiation in endothelial cells and has demonstrated a link between this pathway and cytoskeletal remodeling and permeability. The results also suggest that the RhoA pathway might be a useful target for modulating the permeability and other effects of radiation for therapeutic gain.

Gabrys, Dorota [Department of Radiation Oncology, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch, Gliwice (Poland); Greco, Olga [Cancer Research UK Tumour Microcirculation Group, Academic Unit of Surgical Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield (United Kingdom); Patel, Gaurang; Prise, Kevin M. [Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland (United Kingdom); Tozer, Gillian M. [Cancer Research UK Tumour Microcirculation Group, Academic Unit of Surgical Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield (United Kingdom); Kanthou, Chryso [Cancer Research UK Tumour Microcirculation Group, Academic Unit of Surgical Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield (United Kingdom)], E-mail: C.Kanthou@sheffield.ac.uk

2007-12-01

186

Permeable Pavements, Green Roofs, and Cisterns  

E-print Network

asphalt and concrete, which are completely impervious surfaces. Permeable pavements allow water site features, reduc- monplace throughout North Carolina, ing and disconnecting impervious cover concrete, pervious asphalt, permeable interlocking concrete pavers (PICPs), concrete grid pavers

Hunt, William F.

187

Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock.  

PubMed

Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO2 in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO2 at 40°C and 10?MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of -0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock. PMID:23633894

Ellis, Brian R; Fitts, Jeffrey P; Bromhal, Grant S; McIntyre, Dustin L; Tappero, Ryan; Peters, Catherine A

2013-04-01

188

Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock  

SciTech Connect

Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO{sub 2} in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO{sub 2} at 40°C and 10?MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of ?0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock.

Ellis, Brian R.; Fitts, Jeffrey P.; Bromhal, Grant S.; McIntyre, Dustin L.; Tappero, Ryan; Peters, Catherine

2013-04-01

189

Novel additives to retard permeable flow  

SciTech Connect

Low concentrations of surfactant and cosolute in water, can selectively retard permeable flow in high permeability rocks compared to low permeability ones. This represents a way forward for more efficient areal sweep efficiency when water flooding a reservoir during improved oil recovery. (author)

Golombok, Michael [Shell Exploration and Production, Kessler Park 1, 2288 GS Rijswijk (Netherlands); Department of Mechanical Engineering, Technische Universiteit Eindhoven, 5600 MB Eindhoven (Netherlands); Crane, Carel; Ineke, Erik; Welling, Marco [Shell Exploration and Production, Kessler Park 1, 2288 GS Rijswijk (Netherlands); Harris, Jon [Shell Exploration and Production, Kessler Park 1, 2288 GS Rijswijk (Netherlands); Shell UK Ltd., North Anderson Drive, Aberdeen, AB15 6BL (United Kingdom)

2008-09-15

190

Microscale permeability predictions of porous fibrous media  

Microsoft Academic Search

A good understanding of woven fiber preform permeabilities is critical in the design and optimization of the composite molding processes encountered in resin transfer molding (RTM); yet these issues remain unresolved in the literature. Many have attempted to address permeability predictions for flat undeformed fiber preform, but few have investigated permeability variations for complex geometries of porous fibrous media. In

N. D. Ngo; K. K. Tamma

2001-01-01

191

STEAM-WATER RELATIVE PERMEABILITY A DISSERTATION  

E-print Network

STEAM-WATER RELATIVE PERMEABILITY A DISSERTATION SUBMITTED TO THE DEPARTMENT OF PETROLEUM Laboratory. iv #12;ABSTRACT Steam-water relative permeability curves are required for mathematical models of two-phase geothermal reservoirs. In this study, drainage steam- water relative permeabilities were

Stanford University

192

The measurement of gas relative permeability for low permeability cores using a pressure transient method  

E-print Network

of measurements on capillary pressure versus water saturation, absolute permeability versus net confining pressure and relative permeabiity versus water saturation are presented for eight Trsvis Peak core samples. The results illustrate the utility... Introduction Measurement of Absolute Porosity and Permeability. . . . . . . . . Measurement of Absolute Permeability Versus Net Confining Pres- sure Measurement of Capillary Pressure Versus Water Saturation. . . Measurement of Relative Permeability Versus...

Ning, Xiuxu

2012-06-07

193

Permeability enhancement using explosive techniques  

SciTech Connect

In situ recovery methods for many of our hydrocarbon and mineral resources depend on the ability to create or enhance permeability in the resource bed to allow uniform and predictable flow. To meet this need, a new branch of geomechanics devoted to computer prediction of explosive rock breakage and permeability enhancement has developed. The computer is used to solve the nonlinear equations of compressible flow, with the explosive behavior and constitutive properties of the medium providing the initial/boundary conditions and material response. Once the resulting computational tool has been verified and calibrated with appropriate large-scale field tests, it can be used to develop and optimize commercially useful explosive techniques for in situ resource recovery.

Adams, T.F.; Schmidt, S.C.; Carter, W.J.

1980-01-01

194

Other vascular tumors.  

PubMed

Vascular tumors are rare in children and adults. Classification of these tumors has been difficult, especially in the pediatric population, due to the rarity of these lesions, the unusual morphologic appearance, their diverse clinical behavior, and no independent stratification for pediatric tumors. In 2013, The World Health Organization updated the classification of soft tissue vascular tumors. Pediatric tumors were not independently stratified and the terminology was mostly left unchanged, but the intermediate category of tumors was divided into locally aggressive and rarely metastasizing. These tumors are treated with multimodality therapy and therefore need the guidance of an interdisciplinary team for best care. PMID:25241094

Adams, Denise M; Hammill, Adrienne

2014-08-01

195

Vascular tumors of bone.  

PubMed

Vascular tumors of the bone represent a variety of neoplasms, ranging from benign hemangiomas and epithelioid hemangiomas to intermediate grade hemangioendotheliomas to frankly malignant angiosarcomas. Over the years, there has been considerable debate concerning the aggressivity, nomenclature, and mere existence of various nosologic entities, due to morphologic similarities and uncertainty regarding biologic behavior. Such debate has led to confusion among pathologists and clinicians, thus diminishing the prognostic implications in the diagnosis of these lesions. Here we review the current knowledge concerning the primary vascular neoplasms of the bone and correlate clinicopathologic features with tumor behavior. PMID:24680180

Hart, Jesse L; Edgar, Mark A; Gardner, Jerad M

2014-01-01

196

Building Vascular Networks  

PubMed Central

Only a few engineered tissues—skin, cartilage, bladder—have achieved clinical success, and biomaterials designed to replace more complex organs are still far from commercial availability. This gap exists in part because biomaterials lack a vascular network to transfer the oxygen and nutrients necessary for survival and integration after transplantation. Thus, generation of a functional vasculature is essential to the clinical success of engineered tissue constructs and remains a key challenge for regenerative medicine. In this Perspective, we discuss recent advances in vascularization of biomaterials through the use of biochemical modification, exogenous cells, or microengineering technology. PMID:23152325

Bae, Hojae; Puranik, Amey S.; Gauvin, Robert; Edalat, Faramarz; Carrillo-Conde, Brenda; Peppas, Nicholas A.; Khademhosseini, Ali

2013-01-01

197

Orientin inhibits high glucose-induced vascular inflammation in vitro and in vivo.  

PubMed

Vascular inflammation plays a key role in the initiation and progression of atherosclerosis, a major complication of diabetes mellitus. Orientin, a C-glycosyl flavonoid, is known to have anxiolytic and antioxidative activity. In this study, we assessed whether orientin can suppress vascular inflammation induced by high glucose (HG) in human umbilical vein endothelial cells (HUVECs) and mice. Our data indicate that HG markedly increased vascular permeability, monocyte adhesion, the expression of cell adhesion molecules (CAMs), the formation of reactive oxygen species (ROS), and the activation of nuclear factor kappa B (NF-?B). Remarkably, the vascular inflammatory effects of HG were attenuated by pretreatment with orientin. Since vascular inflammation induced by HG is critical in the development of diabetic complications, our results suggest that orientin may have significant benefits in the treatment of diabetic complications and atherosclerosis. PMID:24950780

Ku, Sae-Kwang; Kwak, Soyoung; Bae, Jong-Sup

2014-12-01

198

Hyperoside inhibits high-glucose-induced vascular inflammation in vitro and in vivo.  

PubMed

Hyperoside, an active compound from the genera of Hypericum and Crataegus, was reported to have antioxidant, antihyperglycemic, anticancer, anti-inflammatory, and anticoagulant activities. Vascular inflammatory process has been suggested to play a key role in initiation and progression of atherosclerosis, a major complication of diabetes mellitus. Thus, in this study, we attempted to determine whether hyperoside can suppress vascular inflammatory processes induced by high glucose (HG) in human umbilical vein endothelial cells (HUVECs) and mice. Data showed that HG induced markedly increased vascular permeability, monocyte adhesion, expressions of cell adhesion molecules (CAMs), formation of reactive oxygen species (ROS), and activation of nuclear factor (NF)-?B. Remarkably, all of the above-mentioned vascular inflammatory effects of HG were attenuated by pretreatment with hyperoside. Vascular inflammatory responses induced by HG are critical events underlying development of various diabetic complications; therefore, our results suggest that hyperoside may have significant therapeutic benefits against diabetic complications and atherosclerosis. PMID:24609927

Ku, Sae-Kwang; Kwak, Soyoung; Kwon, O-Jun; Bae, Jong-Sup

2014-10-01

199

Mechanisms of Microgravity Effect on Vascular Function  

NASA Technical Reports Server (NTRS)

The overall goal of the project is to characterize the effects of simulated microgravity on vascular function. Microgravity is simulated using the hindlimb unweighted (HU) rat, and the following vessels are removed from HU and paired control rats for in vitro analysis: abdominal aorta, carotid and femoral arteries, jugular and femoral veins. These vessels are cut into 3 mm long rings and mounted in tissue baths for the measurement of either isometric contraction, or relaxation of pre- contracted vessels. The isolated mesenteric vascular bed is perfused for the measurement of changes in perfusion pressure as an index of arteriolar constriction or dilation. This report presents, in addition to the statement of the overall goal of the project, a summary list of the specific hypotheses to be tested. These are followed by sections on results, conclusions, significance and plans for the next year.

Purdy, Ralph E.

1995-01-01

200

Vascular air embolism  

PubMed Central

Vascular air embolism is a rare but potentially fatal event. It may occur in a variety of procedures and surgeries but is most often associated as an iatrogenic complication of central line catheter insertion. This article reviews the incidence, pathophysiology, diagnosis, treatment, and prevention of this phenomenon. PMID:23724390

Gordy, Stephanie; Rowell, Susan

2013-01-01

201

Vascular complications of osteochondromas  

Microsoft Academic Search

Purpose: Osteochondromas are the most common benign tumor of the bone. They are sometimes responsible for vascular complications involving either veins or arteries, principally around the knee.Methods: We report six cases of such complications. An extensive review of literature through a computerized research was performed.Results: We found 97 cases that were previously reported in the English literature giving sufficient details

Marc-Antoine Vasseur; Oliver Fabre

2000-01-01

202

Factors affecting relative permeabilities during simultaneous flow of oil and polymer solution through porous media  

SciTech Connect

Buckley-Leverett theory has been modified for power-law fluids and modified fractional flow curves were obtained. The Johnson, Bossler, and Nauman method was modified to calculate individual relative permeabilities in multiphase systems from experimental data obtained for fired Berea sandstone cores using kerosene and polymer solutions. Two polyacrylamide polymers, having different molecular weights, were used to prepare polymer solutions at various concentrations (500-1500 ppm). Analytical results indicate that for a constant flow rate, the polymer solution fractional flow curve is an increasing function of power-law index (n). Fractional flow curves shift to the left as the flow rate increases for shear-thinning (n < 1) fluids and to the right for shear-thickening (n > 1) fluids. The experimental results show that, in relative permeability calculations, the use of a reference permeability that is decreased by the effect of adsorbed polymer leads to overestimating the non-wetting phase relative permeability. On the other hand, a reference permeability that neglects this adsorbed layer effect leads to underestimating the relative permeability of the wetting phase. The adsorbed layer has little or no effect on the relative permeability of the non-wetting phase. Comparison of relative permeabilities with and without polymer flow suggest that the presence of an adsorbed polymer layer increases the apparent water preferential wettability of the rock. The second drainage unsteady-state data showed that the relative permeability of the wetting phase was reduced, but no effect was observed on the non-wetting phase relative permeability.

Salman, M.J.

1989-01-01

203

Role of cellular cholesterol metabolism in vascular cell calcification.  

PubMed

Vascular calcification impairs vessel compliance and increases the risk of cardiovascular events. We found previously that liver X receptor agonists, which regulate intracellular cholesterol homeostasis, augment PKA agonist- or high phosphate-induced osteogenic differentiation of vascular smooth muscle cells. Because cholesterol is an integral component of the matrix vesicles that nucleate calcium mineral, we examined the role of cellular cholesterol metabolism in vascular cell mineralization. The results showed that vascular smooth muscle cells isolated from LDL receptor null (Ldlr(-/-)) mice, which have impaired cholesterol uptake, had lower levels of intracellular cholesterol and less osteogenic differentiation, as indicated by alkaline phosphatase activity and matrix mineralization, compared with WT cells. PKA activation with forskolin acutely induced genes that promote cholesterol uptake (LDL receptor) and biosynthesis (HMG-CoA reductase). In WT cells, inhibition of cholesterol uptake by lipoprotein-deficient serum attenuated forskolin-induced matrix mineralization, which was partially reversed by the addition of cell-permeable cholesterol. Prolonged activation of both uptake and biosynthesis pathways by cotreatment with a liver X receptor agonist further augmented forskolin-induced matrix mineralization. Inhibition of either cholesterol uptake, using Ldlr(-/-) cells, or of cholesterol biosynthesis, using mevastatin-treated WT cells, failed to inhibit matrix mineralization due to up-regulation of the respective compensatory pathway. Inhibition of both pathways simultaneously using mevastatin-treated Ldlr(-/-) cells did inhibit forskolin-induced matrix mineralization. Altogether, the results suggest that up-regulation of cholesterol metabolism is essential for matrix mineralization by vascular cells. PMID:21835914

Geng, Yifan; Hsu, Jeffrey J; Lu, Jinxiu; Ting, Tabitha C; Miyazaki, Makoto; Demer, Linda L; Tintut, Yin

2011-09-23

204

Correlation of permeability with the structure of the endothelial layer of pulmonary artery intimal explants  

SciTech Connect

Changes in vascular permeability are associated with structural damage to endothelial cells. These functional and structural changes can be produced experimentally and examined by using intimal explants from bovine pulmonary artery. Correlation of functional with structural changes allows the authors to dissect the mechanisms responsible for endothelial damage. They have shown that incubation of intimal explants with histamine causes transient formation of interendothelial dilations and an increased rate of equilibration of tritiated water and (/sup 14/C)sucrose across the intimal explant. Exposure to endotoxin also causes interendothial dilations but the endothelial damage is more severe than that with histamine, and in vivo experiments show a more prolonged increase in pulmonary vascular permeability. Leukocyte migration has also been suggested to result in a decreased barrier function of the endothelial layer. Experiments with the endothelial layer of intimal explants and separated bovine leukocytes suggest that transendothelial migration may depend on the chemotactic stimulus. Migration toward lymphocyte-conditioned medium does result in increased equilibration of (/sup 14/C)sucrose. Finally, a theoretical model has been used to examine the permeability changes seen for the intimal explants exposed to histamine. The model consists of two compartments with radioactive tracers diffusing across a filter of known permeability. Such a model gives good agreement with data obtained in intact sheep, indicating that mathematical models allow quantitative estimates of barrier function in intimal explants that compare favorably with in vivo data.

Meyrick, B.; Perkett, E.A.; Harris, T.R.; Brigham, K.L.

1987-06-01

205

O2 free radical-mediated myocardial and vascular dysfunction.  

PubMed

In the present investigation electrolysis of a physiological buffer solution for 2 min with a constant current (20 mA, DC stainless steel anode) was observed to generate free radicals, determined by a luminol assay. Rabbit isolated hearts perfused with physiological buffer subjected to electrolysis were observed to undergo an increase in coronary artery perfusion pressure (PP) and in left ventricular end-diastolic pressure (LVEDP), 80 +/- 4 and 52 +/- 7 mmHg, respectively. Immediately after electrolysis of the physiological buffer, the hearts were observed to accumulate and retain (8-fold) more 125I-labeled albumin than hearts perfused with normal buffer without electrolysis, indicating an increased vascular permeability. The free radical scavengers, dimethyl sulfoxide (DMSO) and catalase (CAT), provided significant protection of the hearts against the changes in PP, LVEDP, and vascular permeability. This study demonstrates that toxic oxygen species generated independently of circulating blood elements or enzymatic reactions can have a direct effect on the vasculature of an isolated heart leading to alterations in cardiac function. The protection afforded by the addition of DMSO or CAT to the perfusion system would suggest that the OH. radical and H2O2 were the reactive oxygen species involved in producing the observed vascular and cardiac effects. PMID:3789177

Jackson, C V; Mickelson, J K; Pope, T K; Rao, P S; Lucchesi, B R

1986-12-01

206

Engineering Cell-permeable Protein  

PubMed Central

The protein transduction technique enables the direct delivery of biologically active material into mammalian cells [for review see 1,2]. For this one can make use of the translocating ability of so-called cell penetrating peptides (CPPs), also designated as protein transduction domains (PTDs). The TAT-CPP derived from the human immunodeficiency virus type 1 (HIV-1) Tat (trans-activator of transcription) protein has been widely used. The positively charged TAT promotes cell permeability thereby overcoming the barriers of the cellular membrane by endocytosis or/and direct membrane penetration2. In combination with a nuclear localization signal (NLS) fusion proteins are able to enter the nucleus exhibiting functionality. Our video presentation demonstrates, as an exemplification for the engineering of cell-permeable proteins, the construction, production and application of a cell-permeable version of the DNA-modifying enzyme Cre. Cre is a site-specific recombinase that is able to recognize and recombine 34 base pair loxP sites in mammalian cells in vitro and in vivo. Therefore the Cre/loxP system is widely used to conditionally induce mutations in the genome of living cells3,4. The delivery of active Cre recombinase to cells, however, represents a limitation. We describe the pSESAME vector system, which allows a direct insertion of the gene-of-interest and provides a platform to rapidly clone different domains and tags used within the vector in a convenient and standardized manner. Rearranging of the different tags has been shown to modify the biochemical properties of the fusion proteins providing a possibility to achieve higher yield and better solubility. We demonstrate how to express and purify recombinant cell-permeant proteins in and from E. coli. The functionality of the recombinant Cre protein is finally validated in cell culture by assessing its intracellular recombinase activity. PMID:20038937

Munst, Bernhard; Patsch, Christoph; Edenhofer, Frank

2009-01-01

207

The Vascular Depression Hypothesis: Mechanisms Linking Vascular Disease with Depression  

PubMed Central

The ‘Vascular Depression’ hypothesis posits that cerebrovascular disease may predispose, precipitate, or perpetuate some geriatric depressive syndromes. This hypothesis stimulated much research that has improved our understanding of the complex relationships between late-life depression (LLD), vascular risk factors, and cognition. Succinctly, there are well-established relationships between late-life depression, vascular risk factors, and cerebral hyperintensities, the radiological hallmark of vascular depression. Cognitive dysfunction is common in late-life depression, particularly executive dysfunction, a finding predictive of poor antidepressant response. Over time, progression of hyperintensities and cognitive deficits predicts a poor course of depression and may reflect underlying worsening of vascular disease. This work laid the foundation for examining the mechanisms by which vascular disease influences brain circuits and influences the development and course of depression. We review data testing the vascular depression hypothesis with a focus on identifying potential underlying vascular mechanisms. We propose a disconnection hypothesis, wherein focal vascular damage and white matter lesion location is a crucial factor influencing neural connectivity that contributes to clinical symptomatology. We also propose inflammatory and hypoperfusion hypotheses, concepts that link underlying vascular processes with adverse effects on brain function that influence the development of depression. Testing such hypotheses will not only inform the relationship between vascular disease and depression but also provide guidance on the potential repurposing of pharmacological agents that may improve late-life depression outcomes. PMID:23439482

Taylor, Warren D.; Aizenstein, Howard J.; Alexopoulos, George S.

2013-01-01

208

Permeability that changes over time (Invited)  

NASA Astrophysics Data System (ADS)

Permeability is commonly assumed to be a geometrically-controlled constant. However, continuous measurements of permeability from tidal responses reveal that the apparent permeability can change significantly over time. Seismic waves from regional earthquakes can increase the permeability by factors of up to 3-4 and the permeability can recover slowly over a period of years. Permeability changes are correlated to peak ground motion and we can recreate this fundamental observation with laboratory experiments. The mechanism of these permeability enhancements may be the clearing of clogged fractures by fines mobilization. These transient permeability effects are particularly important in fault zones where the hydrogeology is coupled to the strength of the fault. Recently, we have directly measured the permeability recovery within a major fault following the 2008 M7.9 Wenchuan earthquake and showed that the ongoing evolution of the system persists for years after the mainshock. Additionally, permeability enhancements were directly measured in the fault zone at the time of distant earthquakes. These observations suggest that the hydrogeological system records a process coupling the faults over great distances.

Brodsky, E. E.; Xue, L.; Candela, T.; Elkhoury, J. E.

2013-12-01

209

Pelvic vascular malformations.  

PubMed

Vascular malformations (VMs) comprise a wide spectrum of lesions that are classified by content and flow characteristics. These lesions, occurring in both focal and diffuse forms, can involve any organ and tissue plane and can cause significant morbidity in both children and adults. Since treatment strategy depends on the type of malformation, correct diagnosis and classification of a vascular lesion are crucial. Slow-flow VMs (venous and lymphatic malformations) are often treated by sclerotherapy, whereas fast-flow lesions (arteriovenous malformations) are generally managed with embolization. In addition, some cases of VMs are best treated surgically. This review will present an overview of VMs in the female pelvis as well as a discussion of endovascular therapeutic techniques. PMID:24436563

Christenson, Brian M; Gipson, Matthew G; Smith, Mitchell T

2013-12-01

210

Neurobiology of Vascular Dementia  

PubMed Central

Vascular dementia is, in its current conceptual form, a distinct type of dementia with a spectrum of specific clinical and pathophysiological features. However, in a very large majority of cases, these alterations occur in an already aged brain, characterized by a milieu of cellular and molecular events common for different neurodegenerative diseases. The cell signaling defects and molecular dyshomeostasis might lead to neuronal malfunction prior to the death of neurons and the alteration of neuronal networks. In the present paper, we explore some of the molecular mechanisms underlying brain malfunction triggered by cerebrovascular disease and risk factors. We suggest that, in the age of genetic investigation and molecular diagnosis, the concept of vascular dementia needs a new approach. PMID:21876809

Enciu, Ana-Maria; Constantinescu, Stefan N.; Popescu, Laurentiu M.; Muresanu, Dafin F.; Popescu, Bogdan O.

2011-01-01

211

Management of Vascular Malformations  

PubMed Central

Background: Even though vascular malformations are well categorized, further details are relatively unknown. Of treated patients regarding the frequency, demographic distributions, and other related factors by multivariate regression analyses in proportion to total vascular malformations, methods of treatment and how to manage them have not been elucidated thoroughly. Methods: From January 2006 to March 2012, consecutively treated patients with vascular anomalies were included in this investigation at least 1-year follow-up. Results: Of the total of 123 cases, 86 females and 37 males, the mean follow-up was 3.5?±?1.68 years, and the frequency of treatment was 1–8 times (1.8?±?1.30). Surgery was performed for 22 cases (17.9%) of venous malformations and arteriovenous malformations. In multivariate regression, the frequency of treatment was significantly correlated with the length of follow-up (P < 0.001), age (P < 0.05), and type of malformations (P < 0.05) (R2 = 0.18). Need for surgery was significantly increased with age at odds ratio (OR) of 1.06 [95% confidence interval (CI), 1.03–1.80] (P < 0.001), and head/face/neck, and upper limb are more performed at OR of 0.24 (95% CI, 0.07–0.85) (P < 0.05). The satisfaction score varied from 1 to 5 (3.9?±?0.68). Complications occurred in 3 cases (2.4%). In logistic regression of complications, the OR of the satisfaction score was 0.13 (95% CI, 0.02–0.80) (P < 0.05). Conclusions: Treatment of vascular malformations is an integral part of multidisciplinary approaches. Venous malformations are more frequent in combination surgery, and if there are fewer complications, the patients’ satisfaction increases.

Houbara, Seiji; Hirano, Akiyoshi

2014-01-01

212

Vascular Thoracic Outlet Syndrome  

Microsoft Academic Search

  Abstract\\u000a \\u000a The surgical treatment of 30 cases of vascular thoracic outlet syndrome (TOS) in 25 patients is presented. Patients included\\u000a 17 women and 8 men with average age of 26.1 years. The causes of compression were cervical rib (n = 16), soft tissue anomalies (n = 12), and scar tissue after clavicle fracture (n = 2). Ten subclavian artery aneurysms

Lazar B. Davidovic; Dusan M. Kostic; Nenad S. Jakovljevic; Ilija L. Kuzmanovic; Tijana M. Simic

2003-01-01

213

Permeability Properties of Rickettsia mooseri  

PubMed Central

The passive permeability properties of Rickettsia mooseri to both inorganic and organic solutes have been examined. Visual observations by phase-contrast microscopy of rickettsiae in macerated yolk sacs taken directly from heavily infected eggs revealed plasmolysis with hypertonic NaCl and KCl as well as with sucrose solutions. In contrast, similar visual studies of rickettsiae which had been subjected to freezing or to a purification process, or both, were plasmolyzed by hypertonic sucrose but not by hypertonic NaCl and KCl. These primary observations were extended to a variety of solutes and were placed on a quantitative basis by use of optical density and radioisotope dilution methods. Intracellular Na+ and K+ concentrations in processed rickettsiae, measured by flame photometry, closely paralleled the concentration of these ions in the suspending medium. It was concluded that R. mooseri appears to possess an osmotically active, functional, and structural membrane distinct from the cell wall, located at the surface of a structure analogous to the bacterial protoplast. In the intact organism, this membrane is passively impermeable to sucrose, NaCl, and KCl. However, altered permeability properties, especially to inorganic electrolytes, may be expected in rickettsiae which have been stored in the frozen state and subjected to a lengthy purification process. PMID:5337841

Myers, W. F.; Provost, P. J.; Wisseman, C. L.

1967-01-01

214

Evaluation of Test Methods for Permeability (Transport) and Development of Performance Guidelines for Durability  

E-print Network

Tests Rapid Index Tests RCP (ASTM C 1202) RMT (AASHTO TP 64) Sorptivity (ASTM C 1585) Gas Permeability (RILEM-CEMBUREAU) Science-based Tests Chloride Diffusion (ASTM C 1556) Modified Chloride Diffusion (ASTM Standard AASHTO or ASTM tests Step 2 Transform Test Results into Material Properties Step 4 Use Service

215

Pulmonary vascular imaging  

SciTech Connect

A wide range of pulmonary vascular imaging techniques are available for the diagnostic evaluation of patients with suspected pulmonary vascular disease. The characteristics of any ideal technique would include high sensitivity and specificity, safety, simplicity, and sequential applicability. To date, no single technique meets these ideal characteristics. Conventional pulmonary angiography remains the gold standard for the diagnosis of acute thromboembolic disease despite the introduction of newer techniques such as digital subtraction angiography and magnetic resonance imaging. Improved noninvasive lower extremity venous testing methods, particularly impedance plethysmography, and ventilation-perfusion scanning can play significant roles in the noninvasive diagnosis of acute pulmonary emboli when properly applied. Ventilation-perfusion scanning may also be useful as a screening test to differentiate possible primary pulmonary hypertension from chronic thromboembolic pulmonary hypertension. And, finally, angioscopy may be a useful adjunctive technique to detect chronic thromboembolic disease and determine operability. Optimal clinical decision-making, however, will continue to require the proper interpretation of adjunctive information obtained from the less-invasive techniques, applied with an understanding of the natural history of the various forms of pulmonary vascular disease and with a knowledge of the capabilities and shortcomings of the individual techniques.

Fedullo, P.F.; Shure, D.

1987-03-01

216

Triamcinolone acetonide suppresses interleukin-1 beta-mediated increase in vascular endothelial growth factor expression in cultured rat Müller cells  

Microsoft Academic Search

Purpose  Intravitreal injection of triamcinolone acetonide (TA) is used for the treatment of diabetic macular edema and other vitreoretinal\\u000a diseases. Vascular endothelial growth factor (VEGF) plays a key role in regulating vascular permeability associated with macular\\u000a edema. We investigated the effect of TA on the expression of VEGF mRNA and protein induced by interleukin-1 beta (IL-1b) and\\u000a hypoxia in cultured rat

Hirotaka Itakura; Hideo Akiyama; Norikazu Hagimura; Hiroshi Doi; Toru Tanaka; Shoji Kishi; Masahiko Kurabayashi

2006-01-01

217

UV radiation and prostaglandin E2 up-regulate vascular endothelial growth factor (VEGF) in cultured human fibroblasts  

Microsoft Academic Search

Objective and Design: Exposure to UV radiation is responsible for skin erythema and inflammation. PGE2 is an important inflammatory mediator involved in this process and vascular endothelial growth factor (VEGF) is a potent vascular permeability factor mainly produced by epidermal keratinocytes. This study was aimed at determining whether UVB\\/A1 radiation and prostaglandin E2 (PGE2) could modulate the production of VEGF

S. Trompezinski; I. Pernet; D. Schmitt; J. Viac

2001-01-01

218

Towards a characteristic equation for permeability  

E-print Network

) ............................................................................................... 18 2.6a Model CPR-A: calculated versus measured permeability ............................................................ 19 2.6b Model CPR-A: Permeability calculated using Model CPR-A versus permeability calculated using the GRACE Algorithm... ...................................................................................... 20 2.6c Model CPR-A: Calculated c-function values versus measured c-function values ....................... 21 2.7a Model CPR-B: ]exp[ )( 32 1max ccb Fccccak ?? ?=+= — "Clean Sand" Plot (log-log format) — Archie "Dirty Sand" trend...

Siddiqui, Adil Ahmed

2008-10-10

219

Predicting skin permeability from complex chemical mixtures  

SciTech Connect

Occupational and environmental exposure to topical chemicals is usually in the form of complex chemical mixtures, yet risk assessment is based on experimentally derived data from individual chemical exposures from a single, usually aqueous vehicle, or from computed physiochemical properties. We present an approach using hybrid quantitative structure permeation relationships (QSPeR) models where absorption through porcine skin flow-through diffusion cells is well predicted using a QSPeR model describing the individual penetrants, coupled with a mixture factor (MF) that accounts for physicochemical properties of the vehicle/mixture components. The baseline equation is log k {sub p} = c + mMF + a{sigma}{alpha} {sub 2} {sup H} + b{sigma}{beta} {sub 2} {sup H} + s{pi} {sub 2} {sup H} + rR {sub 2} + vV {sub x} where {sigma}{alpha} {sub 2} {sup H} is the hydrogen-bond donor acidity, {sigma}{beta} {sub 2} {sup H} is the hydrogen-bond acceptor basicity, {pi} {sub 2} {sup H} is the dipolarity/polarizability, R {sub 2} represents the excess molar refractivity, and V {sub x} is the McGowan volume of the penetrants of interest; c, m, a, b, s, r, and v are strength coefficients coupling these descriptors to skin permeability (k {sub p}) of 12 penetrants (atrazine, chlorpyrifos, ethylparathion, fenthion, methylparathion, nonylphenol, {rho}-nitrophenol, pentachlorophenol, phenol, propazine, simazine, and triazine) in 24 mixtures. Mixtures consisted of full factorial combinations of vehicles (water, ethanol, propylene glycol) and additives (sodium lauryl sulfate, methyl nicotinate). An additional set of 4 penetrants (DEET, SDS, permethrin, ricinoleic acid) in different mixtures were included to assess applicability of this approach. This resulted in a dataset of 16 compounds administered in 344 treatment combinations. Across all exposures with no MF, R{sup 2} for absorption was 0.62. With the MF, correlations increased up to 0.78. Parameters correlated to the MF include refractive index, polarizability and log (1/Henry's Law Constant) of the mixture components. These factors should not be considered final as the focus of these studies was solely to determine if knowledge of the physical properties of a mixture would improve predicting skin permeability. Inclusion of multiple mixture factors should further improve predictability. The importance of these findings is that there is an approach whereby the effects of a mixture on dermal absorption of a penetrant of interest can be quantitated in a standard QSPeR model if physicochemical properties of the mixture are also incorporated.

Riviere, Jim E. [Center for Chemical Toxicology Research and Pharmacokinetics, 4700 Hillsborough Street, North Carolina State University, Raleigh, NC 27606 (United States)]. E-mail: Jim_Riviere@ncsu.edu; Brooks, James D. [Center for Chemical Toxicology Research and Pharmacokinetics, 4700 Hillsborough Street, North Carolina State University, Raleigh, NC 27606 (United States)

2005-10-15

220

Noncontact monitoring of vascular lesion phototherapy efficiency by RGB multispectral imaging  

NASA Astrophysics Data System (ADS)

A prototype low-cost RGB imaging system consisting of a commercial RGB CMOS sensor, RGB light-emitting diode ring light illuminator, and a set of polarizers was designed and tested for mapping the skin erythema index, in order to monitor skin recovery after phototherapy of vascular lesions, such as hemangiomas and telangiectasias. The contrast of erythema index (CEI) was proposed as a parameter for quantitative characterization of vascular lesions. Skin recovery was characterized as a decrease of the CEI value relative to the value before the treatment. This approach was clinically validated by examining 31 vascular lesions before and after phototherapy.

Jakovels, Dainis; Kuzmina, Ilona; Berzina, Anna; Valeine, Lauma; Spigulis, Janis

2013-12-01

221

Role of sulfhydryls in mucosal injury caused by ethanol: relation to microvascular permeability, gastric motility and cytoprotection  

SciTech Connect

The relationship between gastric mucosal glutathione (GSH) levels, vascular permeability, gastric motility and mucosal injury caused by ethanol was investigated in rats. Oral administration of 50% ethanol (1 ml) produced elongated reddish bands of lesions in the mucosa with a significant reduction of GSH levels and increase of microvascular permeability. These lesions were significantly inhibited by pretreatment with s.c. administered diethylmaleate (DEM: 1 ml/kg), cysteamine (100 mg/kg) and 16, 16-dimethyl prostaglandin E2 (dmPGE2, 10 micrograms/kg) but worsened markedly by N-ethylmaleimide (NEM: 10 mg/kg). Irrespective of whether the animals were treated with 50% ethanol or not, the mucosal GSH levels were significantly decreased or increased, respectively, by DEM or cysteamine, and were not affected by both NEM and dmPGE2. NEM significantly enhanced the vascular permeability in the absence or presence of ethanol (greater than 10%), whereas other agents significantly inhibited only the increased vascular permeability caused by ethanol. On the other hand, gastric motility was potently and persistently inhibited by either DEM, cysteamine or dmPGE2 at the doses which prevented ethanol-induced mucosal injury, whereas NEM had no effect on the motility. These results suggest that 1) the mucosal GSH levels do not relate directly to either development or prevention of ethanol-induced gastric injury, 2) potentiation by NEM of the mucosal injury may be accounted for by its enhancement of the vascular permeability and 3) inhibition of gastric motility may be associated with prevention of mucosal lesions.

Takeuchi, K.; Okada, M.; Niida, H.; Okabe, S.

1989-02-01

222

Vascular endothelial hyperpermeability induces the clinical symptoms of Clarkson disease (the systemic capillary leak syndrome)  

PubMed Central

The systemic capillary leak syndrome (SCLS) is a rare disorder characterized by transient episodes of hypotensive shock and anasarca thought to arise from reversible microvascular barrier dysfunction. Although the high prevalence of a monoclonal gammopathy of unknown significance in SCLS suggests a pathogenic contribution of endogenous immunoglobulins, the mechanisms of vascular hyperpermeability remain obscure. Herein, we report clinical and molecular findings on 23 patients, the largest SCLS case series to date. Application of episodic SCLS sera, but neither the purified immunoglobulin fraction nor sera obtained from patients during remission, to human microvascular endothelial cells caused vascular endothelial cadherin internalization, disruption of interendothelial junctions, actin stress fiber formation, and increased permeability in complementary functional assays without inducing endothelial apoptosis. Intravenous immunoglobulin, one promising therapy for SCLS, mitigated the permeability effects of episodic sera. Consistent with the presence of endogenous, nonimmunoglobulin, circulating permeability factor(s) constrained to SCLS episodes, we found that vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang2), were elevated in episodic SCLS sera but not in remission sera. Ab-based inhibition of Ang2 counteracted permeability induced by episodic SCLS sera. Comparable experiments with anti-VEGF Ab (bevacizumab) yielded less interpretable results, probably because of endothelial toxicity of VEGF withdrawal. Our results support a model of SCLS pathogenesis in which nonimmunoglobulin humoral factors such as VEGF and Ang2 contribute to transient endothelial contraction, suggesting a molecular mechanism for this highly lethal disorder. PMID:22411873

Xie, Zhihui; Ghosh, Chandra C.; Patel, Roshni; Iwaki, Shoko; Gaskins, Donna; Nelson, Celeste; Jones, Nina; Greipp, Philip R.

2012-01-01

223

Borosilicate films as permeability barriers  

NASA Astrophysics Data System (ADS)

Borosilicate films have been deposited using rf-sputtering techniques from a composite target at room temperature onto polypropylene (PP), high density polyethylene(HDPE), low density polyethylene(LDPE), and polyethylene terephthalate (PETG) substrates. Films were found to be smooth, flexible, with excellent adhesion to the substrates. Repeated rolling the coated substrates on a radius of 0.5mm resulted in no discernable damage for films less than 200nm in thickness. Creasing the substrates did result in local damage. However excellent adhesion did not allow the fractured glass to come off the substrate. Heat generated during deposition only influenced the films grown on LDPE where the thermal expansion mismatch between the film and substrate induced strains caused fractures in thick films. Modifications to processing parameters allowed thick films to be grown without fractures. Permeability measurements of nitrogen resulted in significant improvements in comparison to uncoated substrates.

Applegate, J. R.; Steinmetz, C. E.; Hettinger, J. D.; Carroll, J. F.; Krchnavek, R.

2009-03-01

224

Salt sensitivity and cell permeability.  

PubMed

We have recently shown that changes in blood sodium concentration within the limited range of +/- 15 mmol/l induce changes in blood pressure which are directly related to intracellular sodium concentration and inversely related to the transmembrane sodium gradient. It followed from this that the blood pressure response to an incremental change in blood sodium concentration induced by an intraperitoneal salt load should be a function of the rate of accumulation of cell sodium. This was tested in rats treated with deoxycorticosterone acetate (DOCA)-saline for 3 days since at this time cell permeability to sodium is known to be increased. The rise of cell sodium when blood sodium concentration, measured 30 min after loading, ranged from 140-160 mmol/l, was significantly increased in treated animals (0.14 versus 0.21 mmol/kg dry weight for each 1 mmol/l rise in extracellular sodium concentration) and the rise in blood pressure was correspondingly greater (0.81 versus 1.43 mmHg for a 1 mmol/l rise in extracellular sodium concentration). The increased accumulation of cell sodium was not accompanied by a similar increase in water, so that the rise in intracellular sodium concentration was also exaggerated. Prior uninephrectomy slowed the excretion of the salt load sufficiently to exaggerate the rise of blood sodium concentration in response to a given load. The osmotic effects of intraperitoneal high sodium or high sucrose were both equally reduced, indicating that the increased permeability induced by DOCA is not specific for sodium but affects non-electrolytes as well; thus, it probably involves the phospholipid matrix. PMID:1663979

Friedman, S M

1991-09-01

225

The role of ADAM-mediated shedding in vascular biology.  

PubMed

Within the vasculature the disintegrins and metalloproteinases (ADAMs) 8, 9, 10, 12, 15, 17, 19, 28 and 33 are expressed on endothelial cells, smooth muscle cells and on leukocytes. As surface-expressed proteases they mediate cleavage of vascular surface molecules at an extracellular site close to the membrane. This process is termed shedding and leads to the release of a soluble substrate ectodomain thereby critically modulating the biological function of the substrate. In the vasculature several surface molecules undergo ADAM-mediated shedding including tumour necrosis factor (TNF) ?, interleukin (IL) 6 receptor ?, L-selectin, vascular endothelial (VE)-cadherin, the transmembrane CX3C-chemokine ligand (CX3CL) 1, Notch, transforming growth factor (TGF) and heparin-binding epidermal growth factor (HB-EGF). These substrates play distinct roles in vascular biology by promoting inflammation, permeability changes, leukocyte recruitment, resolution of inflammation, regeneration and/or neovascularisation. Especially ADAM17 and ADAM10 are capable of cleaving many substrates with diverse function within the vasculature, whereas other ADAMs have a more restricted substrate range. Therefore, targeting ADAM17 or ADAM10 by pharmacologic inhibition or gene knockout not only attenuates the inflammatory response in animal models but also affects tissue regeneration and neovascularisation. Recent discoveries indicate that other ADAMs (e.g. ADAM8 and 9) also play important roles in vascular biology but appear to have more selective effects on vascular responses (e.g. on neovascularisation only). Although, targeting of ADAM17 and ADAM10 in inflammatory diseases is still a promising approach, temporal and spatial as well as substrate-specific inhibition approaches are required to minimise undesired side effects on vascular cells. PMID:22138087

Dreymueller, Daniela; Pruessmeyer, Jessica; Groth, Ester; Ludwig, Andreas

2012-01-01

226

The pathobiology of vascular dementia  

PubMed Central

Vascular cognitive impairment defines alterations in cognition, ranging from subtle deficits to full-blown dementia, attributable to cerebrovascular causes. Often coexisting with Alzheimer’s disease, mixed vascular and neurodegenerative dementia has emerged as the leading cause of age-related cognitive impairment. Central to the disease mechanism is the crucial role that cerebral blood vessels play in brain health, not only for the delivery of oxygen and nutrients, but also for the trophic signaling that links inextricably the well being of neurons and glia to that of cerebrovascular cells. This review will examine how vascular damage disrupts these vital homeostatic interactions, focusing on the hemispheric white matter, a region at heightened risk for vascular damage, and on the interplay between vascular factors and Alzheimer’s disease. Finally, preventative and therapeutic prospects will be examined, highlighting the importance of midlife vascular risk factor control in the prevention of late-life dementia. PMID:24267647

Iadecola, Costantino

2013-01-01

227

Diffusion across a Selectively Permeable Membrane  

NSDL National Science Digital Library

Students investigate the effects of molecule size on diffusion across a synthetic selectively permeable membrane. This investigation includes observation and analysis of osmosis (diffusion of water across a selectively permeable membrane). Additional questions guide students in analyzing the relative advantages of different types of model of the cell membrane.

Doherty, Jennifer; Waldron, Ingrid

228

On the dynamic viscous permeability tensor symmetry  

E-print Network

for numerical implementation validation and/or convergence assessment. © 2008 Acoustical Society of America PACS of the Stokes equations system for spatially periodic structures, the permeability is a positive definite mathematically the reasons why the dynamic permeability tensor is sym- metric for spatially periodic structures

Paris-Sud XI, Université de

229

Influence of fiber packing structure on permeability  

NASA Technical Reports Server (NTRS)

The study on the permeability of an aligned fiber bundle is the key building block in modeling the permeability of advanced woven and braided preforms. Available results on the permeability of fiber bundles in the literature show that a substantial difference exists between numerical and analytical calculations on idealized fiber packing structures, such as square and hexagonal packing, and experimental measurements on practical fiber bundles. The present study focuses on the variation of the permeability of a fiber bundle under practical process conditions. Fiber bundles are considered as containing openings and fiber clusters within the bundle. Numerical simulations on the influence of various openings on the permeability were conducted. Idealized packing structures are used, but with introduced openings distributed in different patterns. Both longitudinal and transverse flow are considered. The results show that openings within the fiber bundle have substantial effect on the permeability. In the longitudinal flow case, the openings become the dominant flow path. In the transverse flow case, the fiber clusters reduce the gap sizes among fibers. Therefore the permeability is greatly influenced by these openings and clusters, respectively. In addition to the porosity or fiber volume fraction, which is commonly used in the permeability expression, another fiber bundle status parameter, the ultimate fiber volume fraction, is introduced to capture the disturbance within a fiber bundle.

Cai, Zhong; Berdichevsky, Alexander L.

1993-01-01

230

Nitrate Removal in NITREXTM Permeable Reactive Barriers  

E-print Network

Nitrate Removal in NITREXTM Permeable Reactive Barriers: Investigating Denitrification Using a 15 (particularly of nitrate) to aquatic systems is a growing problem. The NITREXTM Permeable Reactive Barrier (PRB) is a system for removing nitrate in groundwater. We investigated the nitrate removal processes and hydrology

Vallino, Joseph J.

231

Permeability-porosity data sets for sandstones  

USGS Publications Warehouse

Due to the variable nature of permeability-porosity relations, core should be obtained and permeability (k) and porosity (??) should be determined on core plugs in the laboratory for the formation of interest. A catalog of k versus (??) data sets is now available on the Web. Examples from the catalog are considered to illustrate some aspects of k versus ?? dependencies in siliciclastic reservoirs.

Nelson, P. H.

2004-01-01

232

Spontaneous Imbibition in Low Permeability Carbonates  

Microsoft Academic Search

Spontaneous imbibition is important in oil recovery from fractured and low permeability tight gas reservoirs. Gas-water spontaneous imbibition experiments were conducted using low permeability heterogeneous limestone core plugs. The interfacial tension was changed by adding differing amounts of alcohol to water. It was observed that the true residual saturation of gas is very small for all cases. A much larger

Can Ulas Hatiboglu; Ugur Karaaslan; Serhat Akin

2005-01-01

233

SOIL-AIR PERMEABILITY METHOD EVALUATION  

EPA Science Inventory

The feasibility of soil vapor extraction (SVE) is, in part, based on vadose zone soil-air permeability. ield, laboratory and empirical correlation methods for estimating soil-air permeability have been reviewed for their appropriateness in determining SVE feasibility, and the dev...

234

The Effect of a Cerebral Vasodilator, Vinpocetine, on Cerebral Vascular Resistance Evaluated by the Doppler Ultrasonic Technique in Patients with Cerebrovascular Diseases  

Microsoft Academic Search

Changes in cerebral vascular resistance were examined in patients with cerebral circulatory diseases by the Doppler ultrasonic technique after administration of a cerebral vasodilator, vinpocetine, for two months.Continuous index (CI) and pulsatility index (PI) of the blood flow pattern in the internal carotid artery were used as objective parameters for changes in cerebral vascular resistance.1. The CI and PI changed

Manabu Miyazaki

1995-01-01

235

Cell signalling during vascular morphogenesis.  

PubMed

Vascular tissue in plants is unique due to its diverse and dynamic cellular patterns. Through research in several organisms, such as Arabidopsis, Populus and Zinnia, using biochemical, genetic and genomic approaches, significant progress has recently been made in revealing the molecular nature of several signals underlying the patterning of vascular tissue. These signals include ligands, receptors and transcriptional regulators. The future challenge is to understand how the identified signals work together to control vascular morphogenesis. PMID:17233624

Helariutta, Y

2007-02-01

236

Myeloid progenitors differentiate into microglia and promote vascular repair in a model of ischemic retinopathy  

PubMed Central

Vision loss associated with ischemic diseases such as retinopathy of prematurity and diabetic retinopathy are often due to retinal neovascularization. While significant progress has been made in the development of compounds useful for the treatment of abnormal vascular permeability and proliferation, such therapies do not address the underlying hypoxia that stimulates the observed vascular growth. Using a model of oxygen-induced retinopathy, we demonstrate that a population of adult BM–derived myeloid progenitor cells migrated to avascular regions of the retina, differentiated into microglia, and facilitated normalization of the vasculature. Myeloid-specific hypoxia-inducible factor 1? (HIF-1?) expression was required for this function, and we also demonstrate that endogenous microglia participated in retinal vascularization. These findings suggest what we believe to be a novel therapeutic approach for the treatment of ischemic retinopathies that promotes vascular repair rather than destruction. PMID:17111048

Ritter, Matthew R.; Banin, Eyal; Moreno, Stacey K.; Aguilar, Edith; Dorrell, Michael I.; Friedlander, Martin

2006-01-01

237

Vascular endothelial growth factor regulation of Weibel-Palade--body exocytosis  

PubMed Central

Vascular endothelial growth factor (VEGF) not only regulates angiogenesis, vascular permeability, and vasodilation but also promotes vascular inflammation. However, the molecular basis for the proinflammatory effects of VEGF is not understood. We now show that VEGF activates endothelial cell exocytosis of Weibel-Palade bodies, releasing vasoactive substances capable of causing vascular thrombosis and inflammation. VEGF triggers endothelial exocytosis in part through calcium and phospholipase C-? (PLC-?) signal transduction. However, VEGF also modulates endothelial cell exocytosis by activating endothelial nitric oxide synthase (eNOS) production of nitric oxide (NO), which nitrosylates Nethylmaleimide sensitive factor (NSF) and inhibits exocytosis. Thus, VEGF plays a dual role in regulating endothelial exocytosis, triggering pathways that both promote and inhibit endothelial exocytosis. Regulation of endothelial exocytosis may explain part of the proinflammatory effects of VEGF. PMID:15345585

Matsushita, Kenji; Yamakuchi, Munekazu; Morrell, Craig N.; Ozaki, Michitaka; O'Rourke, Brian; Irani, Kaikobad; Lowenstein, Charles J.

2009-01-01

238

Angiotensin II and vascular injury.  

PubMed

Vascular injury, characterized by endothelial dysfunction, structural remodelling, inflammation and fibrosis, plays an important role in cardiovascular diseases. Cellular processes underlying this include altered vascular smooth muscle cell (VSMC) growth/apoptosis, fibrosis, increased contractility and vascular calcification. Associated with these events is VSMC differentiation and phenotypic switching from a contractile to a proliferative/secretory phenotype. Inflammation, associated with macrophage infiltration and increased expression of redox-sensitive pro-inflammatory genes, also contributes to vascular remodelling. Among the many factors involved in vascular injury is Ang II. Ang II, previously thought to be the sole biologically active downstream peptide of the renin-angiotensin system (RAS), is converted to smaller peptides, [Ang III, Ang IV, Ang-(1-7)], that are functional and that modulate vascular tone and structure. The actions of Ang II are mediated via signalling pathways activated upon binding to AT1R and AT2R. AT1R activation induces effects through PLC-IP3-DAG, MAP kinases, tyrosine kinases, tyrosine phosphatases and RhoA/Rho kinase. Ang II elicits many of its (patho)physiological actions by stimulating reactive oxygen species (ROS) generation through activation of vascular NAD(P)H oxidase (Nox). ROS in turn influence redox-sensitive signalling molecules. Here we discuss the role of Ang II in vascular injury, focusing on molecular mechanisms and cellular processes. Implications in vascular remodelling, inflammation, calcification and atherosclerosis are highlighted. PMID:24760441

Montezano, Augusto C; Nguyen Dinh Cat, Aurelie; Rios, Francisco J; Touyz, Rhian M

2014-06-01

239

[Acute hepatic vascular complications].  

PubMed

Acute hepatic vascular complications are rare. Acute portal vein thrombosis (PVT) and the Budd-Chiari syndrome (BSC) are the leading causes. Coagulopathy and local factors are present in up to 80% of cases. Diagnosis is established by colour-coded Doppler sonography, contrast-enhanced computed tomography or magnetic resonance imaging. Patients with acute PVT present with abdominal pain and disturbed intestinal motility. In the absence of cirrhosis anticoagulation with heparin is established followed by oral anticoagulation. In severe cases, surgical thrombectomy or transjugular thrombolysis with stent shunt may be necessary. Acute or fulminant BCS may require emergency liver transplantation or a transjugular intrahepatic portosystemic stent shunt, if patients present with acute liver failure. Milder cases receive anticoagulation for thrombolysis of occluded hepatic veins. Sinusoidal obstruction syndrome (SOS) is diagnosed after total body irradiation or chemotherapy, the term SOS replacing the former veno-occlusive disease. The treatment of congenital vascular malformations, complications in the setting of OLTX as well as patients with hepatic involvement of hereditary hemorrhagic telangiectasia requires significant expertise in a multidisciplinary approach. PMID:21667100

Ochs, A

2011-07-01

240

Defining Vascular Stem Cells  

PubMed Central

Mesenchymal stem cells (MSCs) exist in most adult tissues and have been located near or within blood vessels. Although “perivascular” has been commonly used to describe such locations, increasing evidence points at the vessel wall as the exact location. Thus, “vascular stem cells (VSCs)” is recommended as a more accurate term for MSCs. Furthermore, 2 cell populations, namely pericytes and adventitial progenitor cells (APCs), are the likely VSCs. The pericyte evidence relies on the so-called pericyte-specific markers, but none of these markers is pericyte specific. In addition, pericytes appear to be too functionally diverse and sophisticated to have a large differentiation capacity. On the other hand, APCs are more naïve functionally and, therefore, more akin to being VSCs. In vitro, these cells spontaneously differentiate into pericytes, and can be induced to differentiate into vascular cells (endothelial and smooth muscle cells) and mesenchymal cells (eg, bone, cartilage, and fat). In vivo, indirect evidence also points to their ability to differentiate into mesenchymal cells of their native tissue (eg, fat). Moreover, they possess a large paracrine capacity and, therefore, can help maintain tissue homeostasis by encouraging the replication and differentiation of mesenchymal cells locally. These proposed in vivo functions are areas of interest for future research on VSCs. PMID:23330734

Lue, Tom F.

2013-01-01

241

Understanding vascular development  

PubMed Central

The vasculature of an organism has the daunting task of connecting all the organ systems to nourish tissue and sustain life. This complex network of vessels and associated cells must maintain blood flow but constantly adapt to acute and chronic changes within tissues. While the vasculature has been studied for over a century, we are just beginning to understand the processes that regulate its formation and how genetic hierarchies are influenced by mechanical and metabolic cues to refine vessel structure and optimize efficiency. As we gain insights into the developmental mechanisms, it is clear that the processes that regulate blood vessel development can also enable the adult to adapt to changes in tissues that can be elicited by exercise, aging, injury, or pathology. Thus, research in vessel development has provided tremendous insights into therapies for vascular diseases and disorders, cancer interventions, wound repair and tissue engineering, and in turn, these models have clearly impacted our understanding of development. Here we provide an overview of the development of the vascular system, highlighting several areas of active investigation and key questions that remain to be answered. PMID:23799579

Udan, Ryan S.; Culver, James C.; Dickinson, Mary E.

2014-01-01

242

Effect of pressure-dependent permeability on tight gas wells  

E-print Network

of production data alone, it is impossible to determine the correct permeability value for tight gas reservoirs with pressure-dependent permeability. For the cases studied, the transient performance was similar for both constant permeability and pressure...

Franquet Barbara, Mariela

2005-08-29

243

Computation of permeability of textile reinforcements Bart Verleye1,  

E-print Network

1 Computation of permeability of textile reinforcements Bart Verleye1, , Margrit Klitz3 , Roberto - Permeability of textiles is a key characteristic for composite manufacturing. Measurement of textile permeabil with theory and experimental data. Keywords--Textile composites, Permeability, Finite difference

Sminchisescu, Cristian

244

Intestinal permeability, leaky gut, and intestinal disorders.  

PubMed

A major task of the intestine is to form a defensive barrier to prevent absorption of damaging substances from the external environment. This protective function of the intestinal mucosa is called permeability. Clinicians can use inert, nonmetabolized sugars such as mannitol, rhamnose, or lactulose to measure the permeability barrier or the degree of leakiness of the intestinal mucosa. Ample evidence indicates that permeability is increased in most patients with Crohn's disease and in 10% to 20% of their clinically healthy relatives. The abnormal leakiness of the mucosa in Crohn's patients and their relatives can be greatly amplified by aspirin preadministration. Permeability measurements in Crohn's patients reflect the activity, extent, and distribution of the disease and may allow us to predict the likelihood of recurrence after surgery or medically induced remission. Permeability is also increased in celiac disease and by trauma, burns, and nonsteroidal anti-inflammatory drugs. The major determinant of the rate of intestinal permeability is the opening or closure of the tight junctions between enterocytes in the paracellular space. As we broaden our understanding of the mechanisms and agents that control the degree of leakiness of the tight junctions, we will be increasingly able to use permeability measurements to study the etiology and pathogenesis of various disorders and to design or monitor therapies for their management. PMID:10980980

Hollander, D

1999-10-01

245

Fluid permeability of deformable fracture networks  

SciTech Connect

The authors consider the problem of defining the fracture permeability tensor for each grid lock in a rock mass from maps of natural fractures. For this purpose they implement a statistical model of cracked rock due to M. Oda [1985], where the permeability tensor is related to the crack geometry via a volume average of the contribution from each crack in the population. In this model tectonic stress is implicitly coupled to fluid flow through an assumed relationship between crack aperture and normal stress across the crack. The authors have included the following enhancements to the basic model: (1) a realistic model of crack closure under stress has been added along with the provision to apply tectonic stresses to the fracture system in any orientation, the application of stress results in fracture closure and consequently a reduction in permeability; (2) the fracture permeability can be superimposed onto an arbitrary anisotropic matrix permeability; (3) the fracture surfaces are allowed to slide under the application of shear stress, causing fractures to dilate and result in a permeability increase. Through an example, the authors demonstrate that significant changes in permeability magnitudes and orientations are possible when tectonic stress is applied to a fracture system.

Brown, S.R. [Sandia National Labs., Albuquerque, NM (United States). Geomechanics Dept.; Bruhn, R.L. [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Geology and Geophysics

1997-04-01

246

A Poroelastic Description of Permeability Evolution  

NASA Astrophysics Data System (ADS)

Pore pressure changes in a geothermal reservoir, as a result of injection and/or production of water, result in changes of stress acting on the reservoir rock and, consequently, changes in the mechanical and transport properties of the rock. Bulk modulus and permeability were measured at different pressures and temperatures. An outcropping equivalent of Rotliegend reservoir rock in the North German Basin (Flechtinger sandstone) was used to perform hydrostatic tests and steady state fluid flow tests. Permeability measurements were conducted while cycling confining pressure; the dependence of permeability on stress was determined at a constant downstream pressure of 1 MPa. Also, temperature was increased stepwise from 30 to 140 °C and crack porosity was calculated at different temperatures. Although changes in the volumes of cracks are not significant, the cracks control fluid flow pathways and, consequently, the permeability of the rock. A new model was derived which relates microstructure of porosity, the stress-strain curve, and permeability. Porosity change was described by the first derivative of the stress-strain curve. Permeability evolution was ascribed to crack closure and was related to the second derivative of the stress-strain curve. The porosity and permeability of Flechtinger sandstone were reduced by increasing the effective pressure and decreased after each pressure cycle.

Hassanzadegan, Alireza; Zimmermann, Günter

2014-07-01

247

Anisotropy of permeability in faulted porous sandstones  

NASA Astrophysics Data System (ADS)

Studies of fault rock permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of porous sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host rock porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (?1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted porous sandstone by compaction and reorganisation of grains through shearing and cataclasis.

Farrell, N. J. C.; Healy, D.; Taylor, C. W.

2014-06-01

248

Isolated vascular vertigo.  

PubMed

Strokes in the distribution of the posterior circulation may present with vertigo, imbalance, and nystagmus. Although the vertigo due to a posterior circulation stroke is usually associated with other neurologic symptoms or signs, small infarcts involving the cerebellum or brainstem can develop vertigo without other localizing symptoms. Approximately 11% of the patients with an isolated cerebellar infarction present with isolated vertigo, nystagmus, and postural unsteadiness mimicking acute peripheral vestibular disorders. The head impulse test can differentiate acute isolated vertigo associated with cerebellar strokes (particularly within the territory of the posterior inferior cerebellar artery) from more benign disorders involving the inner ear. Acute audiovestibular loss may herald impending infarction in the territory of anterior inferior cerebellar artery. Appropriate bedside evaluation is superior to MRIs for detecting central vascular vertigo syndromes. This article reviews the keys to diagnosis of acute isolated vertigo syndrome due to posterior circulation strokes involving the brainstem and cerebellum. PMID:25328871

Lee, Hyung

2014-09-01

249

Isolated Vascular Vertigo  

PubMed Central

Strokes in the distribution of the posterior circulation may present with vertigo, imbalance, and nystagmus. Although the vertigo due to a posterior circulation stroke is usually associated with other neurologic symptoms or signs, small infarcts involving the cerebellum or brainstem can develop vertigo without other localizing symptoms. Approximately 11% of the patients with an isolated cerebellar infarction present with isolated vertigo, nystagmus, and postural unsteadiness mimicking acute peripheral vestibular disorders. The head impulse test can differentiate acute isolated vertigo associated with cerebellar strokes (particularly within the territory of the posterior inferior cerebellar artery) from more benign disorders involving the inner ear. Acute audiovestibular loss may herald impending infarction in the territory of anterior inferior cerebellar artery. Appropriate bedside evaluation is superior to MRIs for detecting central vascular vertigo syndromes. This article reviews the keys to diagnosis of acute isolated vertigo syndrome due to posterior circulation strokes involving the brainstem and cerebellum. PMID:25328871

2014-01-01

250

Vascular surgery: Principles and practice  

SciTech Connect

This book contains 24 chapters. Some of the chapter titles are: Radioisotopes and their application to the study of peripheral vascular disease; Noninvasisve studies of peripheral vascular disease; Ultrasound an computerized tomography in the evaluation of arterial aneurysms; Angiography; and Percutaneous transluminal angioplasty.

Wilson, S.E.; Veith, F.J.; Hobson, R.W. II; Williams, R.A.

1987-01-01

251

Interstitial Vascularity in Fibrosing Alveolitis  

Microsoft Academic Search

The aim of this study was to evaluate interstitial vascularity in crypto- humoral autoimmunity, is often associated with lung involve- genic fibrosing alveolitis (CFA) and in fibrosing alveolitis associated ment. Vascular involvement in SSc is exemplified by the with systemic sclerosis (FASSc). Open lung biopsies from eight pa- typical changes of nailfold capillaries, which include enlarged tients with CFA, nine

Elisabetta A. Renzoni; David A. Walsh; Michael Salmon; Athol U. Wells; Andrew G. Nicholson; Srihari Veeraraghavan; Anne E. Bishop; Hanna M. Romanska; Panagiotis Pantelidis; Carol M. Black

2003-01-01

252

[Bone metabolism and cardiovascular function update. Relationship between immune and vascular system in bone tissues].  

PubMed

Bone marrow is a highly vascularized organ and the vessel walls have a large number of fenestrations. Various kinds of hematopoietic cells are continuously entering into and egressing from bone marrow cavity through these unique features. Monocytoid osteoclast precursors also migrate across the capillary endothelium, serving as a dynamic point of control of bone homeostasis. We have recently revealed the cellular dynamics of monocytoid osteoclast precursors in vivo by a novel fluorescent imaging technology. Furthermore we found the regulatory mechanism of vascular permeability in bone marrow in vivo by using intravital multiphoton microscopy. Here we show the latest data and also discuss its further application. PMID:24976057

Kikuta, Junichi; Ishii, Masaru

2014-07-01

253

Vascular PPAR? protects against stroke-induced brain injury  

PubMed Central

Objective To investigate the effects of peroxisome proliferator-activated receptor delta (PPAR?) in the cerebral vasculature following stroke-induced brain injury. Methods and Results Here we report a novel finding that selective PPAR? genetic deletion in vascular smooth muscle cells (VSMCs) resulted in increased cerebrovascular permeability and brain infarction in mice after middle cerebral artery occlusion (MCAO). Mechanistically, we revealed for the first time that PPAR? expression is reduced, but MMP-9 activity is increased in cultured VSMCs after oxygen-glucose deprivation (OGD) and also in the cerebral cortex of mice following MCAO. Moreover, gain- and loss-of-PPAR? function in VSMCs significantly reduces and increases OGD-induced MMP-9 activity, respectively. We have further identified that MMP-9 is a direct target of PPAR?-mediated transrepression by chromatin immunoprecipitation and PPAR? transcriptional activity assays. Furthermore, inhibition of MMP-9 activity by lentiviral MMP-9 shRNA effectively improves cerebrovascular permeability and reduces brain infarction in VSMC-selective PPAR? conditional knockout mice after MCAO. Conclusion Our data demonstrate that PPAR? in VSMCs can prevent ischemic brain injury by inhibition of MMP-9 activation and attenuation of post-ischemic inflammation. The pharmacological activation of PPAR? may provide a new therapeutic strategy to treat stroke-induced vascular and neuronal damage. PMID:21205987

Yin, Ke-Jie; Deng, Zhen; Hamblin, Milton; Zhang, Jifeng; Chen, Y. Eugene

2012-01-01

254

Negative index metamaterial combining magnetic resonators with metal films  

Microsoft Academic Search

We present simulation results of a design for negative index materials that\\u000auses magnetic resonators to provide negative permeability and metal film for\\u000anegative permittivity. We also discuss the possibility of using semicontinuous\\u000ametal films to achieve better manufacturability and enhanced impedance\\u000amatching.

Uday K. Chettiar; Alexander V. Kildishev; Thomas A. Klar; Vladimir M. Shalaev

2006-01-01

255

Hyaluronan regulation of vascular integrity  

PubMed Central

Vascular integrity or the maintenance of blood vessel continuity is a fundamental process regulated, in part, by the endothelial glycocalyx and cell-cell junctions. Defects in endothelial barrier function are an initiating factor in several disease processes including atherosclerosis, ischemia/reperfusion, tumor angiogenesis, cancer metastasis, diabetes, sepsis and acute lung injury. The glycosaminoglycan, hyaluronan (HA), maintains vascular integrity through endothelial glycocalyx modulation, caveolin-enriched microdomain regulation and interaction with endothelial HA binding proteins. Certain disease states increase hyaluronidase activity and reactive oxygen species (ROS) generation which break down high molecular weight HA to low molecular weight fragments causing damage to the endothelial glycocalyx. Further, these HA fragments can activate specific HA binding proteins upregulated in vascular disease to promote actin cytoskeletal reorganization and inhibition of endothelial cell-cell contacts. This review focuses on the crucial role of HA in vascular integrity and how HA degradation promotes vascular barrier disruption. PMID:22254199

Lennon, Frances E; Singleton, Patrick A

2011-01-01

256

Treatment with an LHRH agonist or hCG increases interstitial fluid volume and permeability to Evans blue in the mouse testis.  

PubMed

Treatment of adult mice with 1 microgram of an LHRH-agonist or with 5 i.u. hCG, subcutaneously, resulted in an increase in the permeability to intravenously injected Evans blue into the testicular interstitial space and in the volume of testicular interstitial fluid. These changes are probably related to an increase in vascular permeability but, in contrast to the situation in rats, this was accompanied neither by an accumulation of polymorphonuclear leucocytes in testicular blood vessels nor by the formation of large inter-endothelial cell gaps in postcapillary venules. The mechanisms mediating the gonadotrophin-induced increase in vascular permeability in the mouse testis thus remain unknown. PMID:3148558

Bergh, A; Damber, J E

1988-10-01

257

Quantifying Glomerular Permeability of Fluorescent Macromolecules Using 2-Photon Microscopy in Munich Wistar Rats  

PubMed Central

Kidney diseases involving urinary loss of large essential macromolecules, such as serum albumin, have long been thought to be caused by alterations in the permeability barrier comprised of podocytes, vascular endothelial cells, and a basement membrane working in unison. Data from our laboratory using intravital 2-photon microscopy revealed a more permeable glomerular filtration barrier (GFB) than previously thought under physiologic conditions, with retrieval of filtered albumin occurring in an early subset of cells called proximal tubule cells (PTC)1,2,3. Previous techniques used to study renal filtration and establishing the characteristic of the filtration barrier involved micropuncture of the lumen of these early tubular segments with sampling of the fluid content and analysis4. These studies determined albumin concentration in the luminal fluid to be virtually non-existent; corresponding closely to what is normally detected in the urine. However, characterization of dextran polymers with defined sizes by this technique revealed those of a size similar to serum albumin had higher levels in the tubular lumen and urine; suggesting increased permeability5. Herein is a detailed outline of the technique used to directly visualize and quantify glomerular fluorescent albumin permeability in vivo. This method allows for detection of filtered albumin across the filtration barrier into Bowman's space (the initial chamber of urinary filtration); and also allows quantification of albumin reabsorption by proximal tubules and visualization of subsequent albumin transcytosis6. The absence of fluorescent albumin along later tubular segments en route to the bladder highlights the efficiency of the retrieval pathway in the earlier proximal tubule segments. Moreover, when this technique was applied to determine permeability of dextrans having a similar size to albumin virtually identical permeability values were reported2. These observations directly support the need to expand the focus of many proteinuric renal diseases to included alterations in proximal tubule cell reclamation. PMID:23628966

Sandoval, Ruben M.; Molitoris, Bruce A.

2013-01-01

258

Selective irradiation of the vascular endothelium  

E-print Network

We developed a unique methodology to selectively irradiate the vascular endothelium in vivo to better understand the role of vascular damage in causing normal tissue radiation side-effects.The relationship between vascular ...

Schuller, Bradley W

2007-01-01

259

PERMEABLE REACTIVE BARRIERS FOR GROUNDWATER REMEDIATION  

EPA Science Inventory

Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

260

PERMEABLE REACTIVE BARRIERS FOR GROUND WATER REMEDIATION  

EPA Science Inventory

Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

261

Percolation model of relative permeability hysteresis  

NASA Astrophysics Data System (ADS)

A mathematical model of relative permeability hysteresis in drainage and imbibition is constructed on the basis of percolation theory. It is shown that the results are in qualitatively agreement with experimental data.

Kadet, V. V.; Galechyan, A. M.

2013-05-01

262

Lunar electrical conductivity and magnetic permeability  

NASA Technical Reports Server (NTRS)

Improved analytical techniques are applied to a large Apollo magnetometer data set to yield values of electroconductivity, temperature, magnetic permeability, and iron abundance. Average bulk electroconductivity of the moon is calculated to be .0007 mho/m; a rapid increase with depth to about .003 mho/m within 250 km is indicated. The temperature profile, obtained from the electroconductivity profile for olivine, indicates high lunar temperatures at relatively shallow depths. Magnetic permeability of the moon relative to its environment is calculated to be 1.008 plus or minus .005; a permeability relative to free space of 1.012 plus 0.011, minus 0.008 is obtained. Lunar iron abundances corresponding to this permeability value are 2.5 plus 2.3, minus 1.7 wt% free iron and 5.0-13.5 wt% total iron for a moon composed of a combination of free iron, olivine, and orthopyroxene.

Dyal, P.; Parkin, C. W.; Daily, W. D.

1975-01-01

263

NOVEL ATYPICAL PKC INHIBITORS PREVENT VASCULAR ENDOTHELIAL GROWTH FACTOR-INDUCED BLOOD-RETINAL BARRIER DYSFUNCTION  

PubMed Central

SYNOPSIS Pro-inflammatory cytokines and growth factors such as vascular endothelial growth factor (VEGF) contribute to the loss of the blood-retinal barrier (BRB) and subsequent macular edema in various retinal pathologies. VEGF signaling requires conventional PKC (PKC?) activity; however, PKC? inhibition only partially prevents VEGF-induced endothelial permeability and does not affect pro-inflammatory cytokine-induced permeability suggesting the involvement of alternative signaling pathways. Here, we provide evidence for the involvement of atypical protein kinase C (aPKC) signaling in VEGF-induced endothelial permeability and identify a novel class of inhibitors of aPKC that prevent BRB breakdown in vivo. Genetic and pharmacological manipulations of aPKC isoforms were used to assess their contribution to endothelial permeability in culture. A chemical library was screened using an in vitro kinase assay to identify novel small molecule inhibitors and further medicinal chemistry was performed to delineate a novel pharmacophore. We demonstrate that aPKC isoforms are both sufficient and required for VEGF-induced endothelial permeability. Furthermore, these specific, potent, non-competitive, small molecule inhibitors prevented VEGF-induced tight junction internalization and retinal endothelial permeability in response to VEGF in both primary culture and in rodent retina. These data suggest that aPKC inhibition with 2-amino-4-phenyl-thiophene derivatives may be developed to preserve the BRB in retinal diseases such as diabetic retinopathy or uveitis and the blood-brain barrier (BBB) in the presence of brain tumors. PMID:22721706

Titchenell, Paul M.; Lin, Cheng-Mao; Keil, Jason M.; Sundstrom, Jeffrey M.; Smith, Charles D.; Antonetti, David A.

2013-01-01

264

Water permeability of fly ash concretes  

Microsoft Academic Search

The water permeability of two series of concretes made with one type of fly ash and two types of Portland cement (OPC and\\u000a SRPC) was tested by the method prescribed by DIN 1048. It is concluded that the cementing efficiency factor of the fly ash\\u000a with respect to water permeability is approximately 0.3, independent of type of cement and curing

S. E. Hedegaard; T. C. Hansen

1992-01-01

265

The permeability of fly ash concrete  

Microsoft Academic Search

Oxygen permeability tests were carried out on plain ordinary Portland cement (OPC) and fly ash concretes at three nominal\\u000a strength grades. Prior to testing the concretes were subjected to a wide range of curing and exposure conditions. The results\\u000a emphasize the importance of adequate curing to achieve concrete of low permeability, especially when the ambient relative\\u000a humidity is low. In

M. D. A. Thomas; J. D. Matthews

1992-01-01

266

Osteoprotegerin, vascular calcification and atherosclerosis  

PubMed Central

The association of bone pathologies with atherosclerosis has stimulated the search for common mediators linking the skeletal and the vascular system. Since its initial discovery as a key regulator in bone metabolism, osteoprotegerin (OPG) has become the subject of intense interest for its role in vascular disease and calcification. Studies in vitro and in animal models suggest that OPG inhibits vascular calcification. Paradoxically however, clinical studies suggest that serum OPG levels increase in association with vascular calcification, coronary artery disease, stroke and future cardiovascular events. This has led to extensive debate on the potential of OPG as a biomarker of vascular disease. However the exact significance and mechanisms by which this bone-regulatory protein influences cardiovascular pathophysiology is still unclear. The need for a more complete picture is being addressed in increasing valuable research indicating OPG as not only a marker but also a mediator of vascular pathology modulating osteogenic, inflammatory and apoptotic responses. By integrating the results of recent experimental research, animal models and clinical studies, this review summarises the present understanding of the role of OPG in vascular disease and calcification. PMID:19007931

Van Campenhout, Ann; Golledge, Jonathan

2009-01-01

267

Vascular Injuries: Trends in Management  

PubMed Central

Abstract Vascular injury presents a great challenge to the emergency resident because these injuries require urgent intervention to prevent loss of life or limb. Sometimes serious vascular injury presents with only subtle or occult signs or symptoms. The patient may present weeks or months after initial injury with symptoms of vascular insufficiency, embolization, pseudoaneurysm, arteriovenous fistula etc. Although the majority of vascular injuries are caused by penetrating trauma from gunshot wounds, stabbing or blast injury, the possibility of vascular injury needs to be considered in patients presenting with displaced long bone fractures, crush injury, prolonged immobilization in a fixed position by tight casts or bandages and various invasive procedures. iatrogenic vascular injuries constitute about 10% of cases in most series; however the incidence is an increasing trend because more endovascular procedures such as angioplasty and cardiac catheterization are being performed routinely. Civilian trauma is more frequently seen in young males. However, it can occur at any age due to road accidents, firearms, bomb blasts and diagnostic procedures. Most of the time, civilian trauma causes less tissue damage. There is an epidemic of vascular injuries in Kashmir valley because of problems in law and order in the past two decades. This review deals with the topic in detail. PMID:24350103

Wani, Mohd Lateef; Ahangar, Ab Gani; Ganie, Farooq Ahmad; Wani, Shadab Nabi; Wani, Nasir-ud-din

2012-01-01

268

Role of permeability in sulfate attack  

SciTech Connect

The role of permeability in sulfate attack was evaluated in this study. Resistance to sulfate attack was measured by determining the expansion caused in concrete specimens with exposure 5% Na{sub 2}SO{sub 4} solution. Concrete specimens were prepared from five binders, namely: ordinary Portland cement (OPC), high slag cement (HSC), sulfate-resistance cement (SRC), OPC with 7% silica fume (SF) and HSC with 7% SF. Concrete of grades 35 and 40 were used. The expansions of concrete samples were compared to their permeabilities to establish the role of permeability in controlling the expansion due to sulfate attack. It was found that the relative performance of concretes cannot be explained by either their permeability only or by only the chemical resistance of the binder. However, by combining the information on permeability and the chemical resistance of binder, the relative performance of concretes can be estimated. Thus, both permeability and the type of binder play an important role in sulfate attack.

Khatri, R.P.; Sirivivatnanon, V. [CSIRO Building, Construction and Engineering, North Ryde (Australia)] [CSIRO Building, Construction and Engineering, North Ryde (Australia); Yang, J.L. [Ssang Yong Cement Singapore Ltd., Jurong Town (Singapore)] [Ssang Yong Cement Singapore Ltd., Jurong Town (Singapore)

1997-08-01

269

Proliferative potential of vascular components in human glioblastoma multiforme  

Microsoft Academic Search

Sixteen patients with glioblastoma multiforme received a 1-h intravenous infusion of 5-bromodeoxyuridine (BrdU), 150–200 mg\\/m2 at the start of surgery, to label S-phase cells in tumor tissue. Labeled cells of vascular components and of tumor parenchyma were detected in excised tumor specimens by indirect immunoperoxidase staining using anti-BrdU monoclonal antibodies followed by periodic acid-Schiff staining. The BrdU labeling index (LI,

T. Nagashima; T. Hoshino; K. G. Cho

1987-01-01

270

Expression of olfactory-type cyclic nucleotide-gated channel (CNGA2) in vascular tissues  

Microsoft Academic Search

Cyclic nucleotide-gated (CNG) ion channels are Ca 2+-permeable nonselective cation channels that are directly gated by the binding of cAMP or cGMP. Previous studies have identified the expression of CNGA1 channels in vascular endothelial cells. The opening of CNG channels is expected to result in a rise in endothelial cytosolic Ca 2+, which may trigger multiple physiological changes. In the

Kwong-Tai Cheng; Franky Leung Chan; Yu Huang; Wing-Yee Chan; Xiaoqiang Yao

2003-01-01

271

Vascular Endothelial Growth Factor in Eye Disease  

PubMed Central

Collectively, angiogenic ocular conditions represent the leading cause of irreversible vision loss in developed countries. In the U.S., for example, retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration are the principal causes of blindness in the infant, working age and elderly populations, respectively. Evidence suggests that vascular endothelial growth factor (VEGF), a 40 kDa dimeric glycoprotein, promotes angiogenesis in each of these conditions, making it a highly significant therapeutic target. However, VEGF is pleiotropic, affecting a broad spectrum of endothelial, neuronal and glial behaviors, and confounding the validity of anti-VEGF strategies, particularly under chronic disease conditions. In fact, among other functions VEGF can influence cell proliferation, cell migration, proteolysis, cell survival and vessel permeability in a wide variety of biological contexts. This article will describe the roles played by VEGF in the pathogenesis of retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration. The potential disadvantages of inhibiting VEGF will be discussed, as will the rationales for targeting other VEGF-related modulators of angiogenesis. PMID:18653375

Penn, J.S.; Madan, A.; Caldwell, R.B.; Bartoli, M.; Caldwell, R.W.; Hartnett, M.E.

2012-01-01

272

Bacterial invasion of vascular cell types: vascular infectology and atherogenesis  

PubMed Central

To portray the chronic inflammation in atherosclerosis, leukocytic cell types involved in the immune response to invading pathogens are often the focus. However, atherogenesis is a complex pathological deterioration of the arterial walls, where vascular cell types are participants with regards to deterioration and disease. Since other recent reviews have detailed the role of both the innate and adaptive immune response in atherosclerosis, herein we will summarize the latest developments regarding the association of bacteria with vascular cell types: infections as a risk factor for atherosclerosis; bacterial invasion of vascular cell types; the atherogenic sequelae of bacterial presence such as endothelial activation and blood clotting; and the identification of the species that are able to colonize this niche. The evidence of a polybacterial infectious component of the atheromatous lesions opens the doors for exploration of the new field of vascular infectology and for the study of atherosclerosis microbiome. PMID:22185451

Kozarov, Emil

2012-01-01

273

Defining excellence in vascular neurosurgery.  

PubMed

Success as a vascular neurosurgeon almost always begins with passion, an inherent love for the work that drives an insatiable desire for personal improvement. A personal definition of excellence in vascular neurosurgery includes several fundamental qualities: mastery of the basics, refinement of technique, advancement of technology, investigative study, advanced decision making, microsurgical innovation, a well-rounded surgical armamentarium, and a lifelong commitment to teaching. Ultimately, the reward for these efforts is the ability to influence generations to come, particularly as one follows the rising careers of former trainees, each redefining the term "excellence" in vascular neurosurgery. PMID:21280491

Sanai, Nader; Spetzler, Robert F

2010-01-01

274

Increase in Vascular Permeability and Vasodilation Are Critical for Proangiogenic Effects of Stem Cell Therapy  

Microsoft Academic Search

Background—Proangiogenic cell therapy based on administration of bone marrow-derived mononuclear cells (BMCs) or endothelial progenitor cells (EPCs) is now under investigation in humans for the treatment of ischemic diseases. However, mechanisms leading to the beneficial effects of BMCs and EPCs remain unclear. Methods and Results—BMC- and CD34-derived progenitor cells interacted with ischemic femoral arteries through SDF-1 and CXCR4 signaling and

Ludovic Waeckel; Téni G. Ebrahimian; Olivier Blanc-Brude; Philippe Foubert; Véronique Barateau; Micheline Duriez; José Vilar; Elisabetta Dejana; Gérard Tobelem; Bernard I. Lévy; Jean-Sébastien Silvestre

2010-01-01

275

Measurement of retinal vascular permeability in a rat model using spectroscopic optical coherence tomography  

E-print Network

Optical coherence tomography (OCT), a diagnostic tool which can perform non-contact, noninvasive, cross-sectional imaging of the retina and anterior eye in real time, has dramatically improved in its resolution and speed ...

Choi, Woo Jhon

2011-01-01

276

Laser Vascular Welding  

NASA Astrophysics Data System (ADS)

Vascular tissue fusion by lasers is performed by directing a low energy beam at the apposed edges of the repair. The tissues are approximated with stay sutures or non-reflective instruments and laser energy is passed back-and-forth over the anastomotic site until fusion is achieved. Vessel welding is apparent to the trained eye, as is nonunion caused by inadequate energy delivery. Conversely, excessive energy delivery results in obvious tissue coagulation or vaporization. Fiberoptic laser transmission and hand-eye coordination are adequate for repair or anastomosis of vessels with diameters greater than 3 mm, whereas magnification and precise mechanical control of the laser beam are necessary for microanastomoses of smaller vessels. The laser power (watts, W), and the amount of energy and time required (energy fluence or power density) vary according to the type of laser and the size of the vessels. Although laser repairs can be fashioned in time intervals equal to or slightly longer than those required for suture repairs, the optimum wavelengths and laser parameters for different types of seals are not yet established.

White, Rodney A.; Kopchok, George; White, Geoffrey H.

1988-06-01

277

Autophagy in Vascular Disease  

PubMed Central

Autophagy, or “self eating,” refers to a regulated cellular process for the lysosomal-dependent turnover of organelles and proteins. During starvation or nutrient deficiency, autophagy promotes survival through the replenishment of metabolic precursors derived from the degradation of endogenous cellular components. Autophagy represents a general homeostatic and inducible adaptive response to environmental stress, including endoplasmic reticulum stress, hypoxia, oxidative stress, and exposure to pharmaceuticals and xenobiotics. Whereas elevated autophagy can be observed in dying cells, the functional relationships between autophagy and programmed cell death pathways remain incompletely understood. Preclinical studies have identified autophagy as a process that can be activated during vascular disorders, including ischemia–reperfusion injury of the heart and other organs, cardiomyopathy, myocardial injury, and atherosclerosis. The functional significance of autophagy in human cardiovascular disease pathogenesis remains incompletely understood, and potentially involves both adaptive and maladaptive outcomes, depending on model system. Although relatively few studies have been performed in the lung, our recent studies also implicate a role for autophagy in chronic lung disease. Manipulation of the signaling pathways that regulate autophagy could potentially provide a novel therapeutic strategy in the prevention or treatment of human disease. PMID:20160147

Ryter, Stefan W.; Lee, Seon-Jin; Smith, Akaya; Choi, Augustine M. K.

2010-01-01

278

Education in vascular access.  

PubMed

The successful creation and use of an arteriovenous vascular access (VA) requires a coordinated, educated multidisciplinary team to ensure an optimal VA for each patient. Patient education programs on VA are associated with increased arteriovenous VA use at dialysis initiation. Education should be tailored to patient goals and preferences with the understanding that experiential education from patient to patient is far more influential than that provided by the healthcare professional. VA education for the nephrologist should focus on addressing the systematic and patient-level barriers in achieving a functional VA, with specific components relating to VA creation, maturation, and cannulation that consider patient goals and preferences. A deficit in nursing skills in the area of assessment and cannulation can have devastating consequences for hemodialysis patients. Delivery of an integrated education program increases nurses' knowledge of VA and development of simulation programs or constructs to assist in cannulation of the VA will greatly facilitate the much needed skill transfer. Adequate VA surgical training and experience are critical to the creation and outcomes of VA. Simulations can benefit nephrologists, dialysis nurses surgeons, and interventionalists though aiding in surgical creation, understanding of the physiology and anatomy of a dysfunctional VA, and practicing cannulation techniques. All future educational initiatives must emphasize the importance of multidisciplinary care to attain successful VA outcomes. PMID:23432319

Moist, Louise M; Lee, Timmy C; Lok, Charmaine E; Al-Jaishi, Ahmed; Xi, Wang; Campbell, Vern; Graham, Janet; Wilson, Barb; Vachharajani, Tushar J

2013-01-01

279

Digital image processing of vascular angiograms  

NASA Technical Reports Server (NTRS)

The paper discusses the estimation of the degree of atherosclerosis in the human femoral artery through the use of a digital image processing system for vascular angiograms. The film digitizer uses an electronic image dissector camera to scan the angiogram and convert the recorded optical density information into a numerical format. Another processing step involves locating the vessel edges from the digital image. The computer has been programmed to estimate vessel abnormality through a series of measurements, some derived primarily from the vessel edge information and others from optical density variations within the lumen shadow. These measurements are combined into an atherosclerosis index, which is found in a post-mortem study to correlate well with both visual and chemical estimates of atherosclerotic disease.

Selzer, R. H.; Beckenbach, E. S.; Blankenhorn, D. H.; Crawford, D. W.; Brooks, S. H.

1975-01-01

280

Rat Tumor Response to the Vascular-Disrupting Agent 5,6-Dimethylxanthenone-4-Acetic Acid as Measured by Dynamic Contrast-Enhanced Magnetic Resonance Imaging, Plasma 5-Hydroxyindoleacetic Acid Levels, and Tumor Necrosis1  

PubMed Central

Abstract The dose-dependent effects of 5,6-dimethylxanthenone-4-acetic acid (DMXAA) on rat GH3 prolactinomas were investigated in vivo. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used to assess tumor blood flow/permeability pretreatment and 24 hours posttreatment with 0, 100, 200, or 350 mg/kg DMXAA. DCE-MRI data were analyzed using Ktrans and the integrated area under the gadolinium time curve (IAUGC) as response biomarkers. Highperformance liquid chromatography (HPLC) was used to determine the plasma concentration of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) following treatment to provide an index of increased vessel permeability and vascular damage. Finally, tumor necrosis was assessed by grading hematoxylin and eosin-stained sections cut from the same tumors investigated by MRI. Both tumor Ktrans and IAUGC were significantly reduced 24 hours posttreatment with 350 mg/kg DMXAA only, with no evidence of dose response. HPLC demonstrated a significant increase in plasma 5-HIAA 24 hours posttreatment with 200 and 350 mg/kg DMXAA. Histologic analysis revealed some evidence of tumor necrosis following treatment with 100 or 200 mg/kg DMXAA, reaching significance with 350 mg/kg DMXAA. The absence of any reduction in Ktrans or IAUGC following treatment with 200 mg/kg, despite a significant increase in 5-HIAA, raises concerns about the utility of established DCE-MRI biomarkers to assess tumor response to DMXAA. PMID:16611413

McPhail, Lesley D; McIntyre, Dominick J O; Ludwig, Christian; Kestell, Philip; Griffiths, John R; Kelland, Lloyd R; Robinson, Simon P

2006-01-01

281

Total transmission and total reflection by zero index materials  

E-print Network

In this report, we achieved total transmission and reflection in a slab of zero index materials with defect(s). By controlling the defect's radius and dielectric constant, we can obtain total transmission and reflection of EM wave. The zero index materials, in this report, stand for materials with permittivity and permeability which are simultaneously equal to zero or so called matched impedance zero index materials. Along with theoretical calculations and simulation demonstrations, we also discuss about some possible applications for the proposed structure such as shielding or cloaking an object without restricting its view. We also suggest a way to control total transmission and reflection actively by using tunable refractive index materials such as liquid crystal and BST. The physics behind those phenomena is attributed to intrinsic properties of zero index materials: constant field inside zero index slab.

Viet Cuong Nguyen; Lang Chen

2010-07-01

282

Permeability of the blood-ocular barrier in adolescent and adult diabetic patients.  

PubMed Central

The permeability of the blood-ocular barrier was examined by fluorophotometry in adolescent and adult diabetic patients before the onset of retinopathy. The adolescent group consisted of 52 eyes of 52 insulin dependent diabetic patients aged 11 to 19 years and a control group of 10 eyes of 10 normal adolescents. The adult group consisted of 74 eyes of 74 non-insulin dependent diabetics and a control group of 30 eyes of 30 normal adults. The increase in lens autofluorescence in the adolescent diabetic patients compared with the controls was striking and showed a significant positive correlation (r = 0.79, p < 0.0001) with the duration of diabetes. Anterior chamber (AQ) values, an index of the permeability of the blood-aqueous barrier (BAB), increased in the adolescent diabetic patients compared with the controls and showed a significant positive correlation with glycosylated haemoglobin levels. No significant differences from the controls were observed regarding the permeability of the blood-retinal barrier (BRB). In the adult group there was no significant difference in either the permeability of the BRB or the AQ values between the diabetic and the control groups. Our results suggest that adolescent diabetic patients differ from adults in that BAB permeability is increased before the onset of retinopathy, suggesting that this is the cause of the striking increase in lens autofluorescence. PMID:8457507

Yoshida, A; Ishiko, S; Kojima, M; Ogasawara, H

1993-01-01

283

Effect of cotton, hemp, and flax dust extracts on lung permeability in the guinea pig.  

PubMed

Byssinosis is an occupational lung disease in textile mill workers exposed to the respirable dusts of cotton, hemp, and flax. This study investigated the influence of aqueous extracts from these dusts on overall lung permeability in the guinea pig as an index of respiratory epithelial damage. Lung permeability was assessed by absorption into blood from the lung of inhaled technetium-99m diethylenetriamine penta-acetate (Tc-DTPA) using gamma-scintigraphy. The half-life for Tc-DTPA absorption (t1/2) was significantly reduced following a 4-week inhalation treatment with cotton, hemp, or flax dust extracts when compared to saline control. There was at least a partial return to normal permeability 7 days after stopping treatment. A single inhalation of extract did not affect the t1/2, but increased the number of neutrophils in bronchoalveolar lavage fluid 24 h postexposure. Neutrophil migration into the airspaces therefore appeared to precede the increased lung permeability. Long-term exposure was not associated with respiratory epithelial shedding, suggesting that the increased permeability reflects a loss of epithelial tight junction integrity arising from repeated exposure to as yet undefined agents in these dusts. PMID:8556986

Bates, P J; Farr, S J; Nicholls, P J

1995-01-01

284

Piezo1 integration of vascular architecture with physiological force.  

PubMed

The mechanisms by which physical forces regulate endothelial cells to determine the complexities of vascular structure and function are enigmatic. Studies of sensory neurons have suggested Piezo proteins as subunits of Ca(2+)-permeable non-selective cationic channels for detection of noxious mechanical impact. Here we show Piezo1 (Fam38a) channels as sensors of frictional force (shear stress) and determinants of vascular structure in both development and adult physiology. Global or endothelial-specific disruption of mouse Piezo1 profoundly disturbed the developing vasculature and was embryonic lethal within days of the heart beating. Haploinsufficiency was not lethal but endothelial abnormality was detected in mature vessels. The importance of Piezo1 channels as sensors of blood flow was shown by Piezo1 dependence of shear-stress-evoked ionic current and calcium influx in endothelial cells and the ability of exogenous Piezo1 to confer sensitivity to shear stress on otherwise resistant cells. Downstream of this calcium influx there was protease activation and spatial reorganization of endothelial cells to the polarity of the applied force. The data suggest that Piezo1 channels function as pivotal integrators in vascular biology. PMID:25119035

Li, Jing; Hou, Bing; Tumova, Sarka; Muraki, Katsuhiko; Bruns, Alexander; Ludlow, Melanie J; Sedo, Alicia; Hyman, Adam J; McKeown, Lynn; Young, Richard S; Yuldasheva, Nadira Y; Majeed, Yasser; Wilson, Lesley A; Rode, Baptiste; Bailey, Marc A; Kim, Hyejeong R; Fu, Zhaojun; Carter, Deborah A L; Bilton, Jan; Imrie, Helen; Ajuh, Paul; Dear, T Neil; Cubbon, Richard M; Kearney, Mark T; Prasad, K Raj; Evans, Paul C; Ainscough, Justin F X; Beech, David J

2014-11-13

285

Social media in vascular surgery.  

PubMed

There has been a tremendous growth in the use of social media to expand the visibility of various specialties in medicine. The purpose of this paper is to describe the latest updates on some current applications of social media in the practice of vascular surgery as well as existing limitations of use. This investigation demonstrates that the use of social networking sites appears to have a positive impact on vascular practice, as is evident through the incorporation of this technology at the Cleveland Clinic and by the Society for Vascular Surgery into their approach to patient care and physician communication. Overall, integration of social networking technology has current and future potential to be used to promote goals, patient awareness, recruitment for clinical trials, and professionalism within the specialty of vascular surgery. PMID:23321344

Indes, Jeffrey E; Gates, Lindsay; Mitchell, Erica L; Muhs, Bart E

2013-04-01

286

Vascular dementia: a historical background.  

PubMed

The history of vascular dementia can be traced back to cases of dementia postapoplexy described by Thomas Willis in 1672. During most of the 18th and early 19th century, "brain congestion" (due in all likelihood to the effects of untreated hypertension) was the most frequent diagnosis for conditions ranging from stroke to anxiety and to cognitive decline, and bloodletting became the commonplace therapy. The modern history of vascular dementia began in 1894 with the contributions of Otto Binswanger and Alois Alzheimer, who separated vascular dementia from dementia paralytica caused by neurosyphilis. In the 1960s, the seminal neuropathological and clinical studies of the New Castle school in England inaugurated the modern era of vascular dementia. PMID:16191211

Román, Gustavo

2003-01-01

287

Biomaterials for vascular tissue engineering  

PubMed Central

Cardiovascular disease is the leading cause of mortality in the USA. The limited availability of healthy autologous vessels for bypass grafting procedures has led to the fabrication of prosthetic vascular conduits. While synthetic polymers have been extensively studied as substitutes in vascular engineering, they fall short of meeting the biological challenges at the blood–material interface. Various tissue engineering strategies have emerged to address these flaws and increase long-term patency of vascular grafts. Vascular cell seeding of scaffolds and the design of bioactive polymers for in situ arterial regeneration have yielded promising results. This article describes the advances made in biomaterials design to generate suitable materials that not only match the mechanical properties of native vasculature, but also promote cell growth, facilitate extracellular matrix production and inhibit thrombogenicity. PMID:20017698

Ravi, Swathi; Chaikof, Elliot L

2010-01-01

288

Nucleic acid indexing  

DOEpatents

A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

Guilfoyle, Richard A. (Madison, WI); Guo, Zhen (Bellevue, WA)

2001-01-01

289

Nucleic acid indexing  

DOEpatents

A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

Guilfoyle, Richard A. (Madison, WI); Guo, Zhen (Bellevue, WA)

1999-01-01

290

Lobby index in networks  

NASA Astrophysics Data System (ADS)

We propose a new node centrality measure in networks, the lobby index, which is inspired by Hirsch’s h-index. It is shown that in scale-free networks with exponent ? the distribution of the l-index has power tail with exponent ?(?+1). Properties of the l-index and extensions are discussed.

Korn, A.; Schubert, A.; Telcs, A.

2009-06-01

291

KSC Construction Cost Index  

NASA Technical Reports Server (NTRS)

Kennedy Space Center cost Index aids in conceptual design cost estimates. Report discusses development of KSC Cost Index since January 1974. Index since January 1974. Index provides management, design engineers, and estimators an up-to-data reference for local labor and material process. Also provides mount and rate of change in these costs used to predict future construction costs.

Brown, J. A.

1983-01-01

292

Molecular mechanisms of vascular pattern formation  

Microsoft Academic Search

Vascular plants have developed a complex network of vascular systems through the plant body, allowing efficient transport of water, nutrients and signals. To understand molecular mechanisms of vascular pattern formation, we have made two approaches. First we have isolated Arabidopsis mutants with defects in vascular pattern formation. Microscopic and genetic examination of the cotyledonary venation of 3400 M3 lines led

Hiroo Fukuda; Koji Koizumi; Kenji Motomatsu; Hiroyasu Motose; Munetaka Sugiyama

2001-01-01

293

LISTA ROJA 2008 DE LA FLORA VASCULAR  

E-print Network

LISTA ROJA 2008 DE LA FLORA VASCULAR ESPA�OLA 2008 red list of spanish vascular flora Coordinador: J.C. Moreno LISTAROJA2008DELAFLORAVASCULARESPA�OLA #12;#12;#12;Lista Roja 2008 de la Flora Vascular François TAPIA Coordinación de la Lista Roja 2008 de la flora vascular española Juan Carlos MORENO SAIZ

Moreno Saiz, Juan Carlos

294

Vascular Waveform Analysis of Flap-Feeding Vessels Using Color Doppler Ultrasonography  

PubMed Central

We performed vascular waveform analysis of flap-feeding vessels using color Doppler ultrasonography and evaluated the blood flow in the flaps prior to surgery. Vascular waveform analysis was performed in 19 patients. The analyzed parameters included the vascular diameter, flow volume, flow velocity, resistance index, pulsatility index, and acceleration time. The arterial waveform was classified into 5 types based on the partially modified blood flow waveform classification reported by Hirai et al.; in particular, D-1a, D-1b, and D-2 were considered as normal waveforms. They were 4 patients which observed abnormal vascular waveform among 19 patients (D-4?:?1, D-3?:?1, and Poor detect?:?2). The case which presented D-4 waveform changed the surgical procedure, and a favorable outcome was achieved. Muscle flap of the case which presented D-3 waveform was partially necrosed. The case which detected blood flow poorly was judged to be the vascular obstruction of the internal thoracic artery. In the evaluation of blood flow in flaps using color Doppler ultrasonography, determination of not only basic blood flow information, such as the vascular distribution and diameter and flow velocity, but also the flow volume, vascular resistance, and arterial waveform is essential to elucidate the hemodynamics of the flap. PMID:24804093

Onishi, Kiyoshi

2014-01-01

295

Systemic Vascular Function Is Associated with Muscular Power in Older Adults  

PubMed Central

Age-associated loss of muscular strength and muscular power is a critical determinant of loss of physical function and progression to disability in older adults. In this study, we examined the association of systemic vascular function and measures of muscle strength and power in older adults. Measures of vascular endothelial function included brachial artery flow-mediated dilation (FMD) and the pulse wave amplitude reactive hyperemia index (PWA-RHI). Augmentation index (AIx) was taken as a measure of systemic vascular function related to arterial stiffness and wave reflection. Measures of muscular strength included one repetition maximum (1RM) for a bilateral leg press. Peak muscular power was measured during 5 repetitions performed as fast as possible for bilateral leg press at 40% 1RM. Muscular power was associated with brachial FMD (r = 0.43, P < 0.05), PWA-RHI (r = 0.42, P < 0.05), and AIx (r = ?0.54, P < 0.05). Muscular strength was not associated with any measure of vascular function. In conclusion, systemic vascular function is associated with lower-limb muscular power but not muscular strength in older adults. Whether loss of muscular power with aging contributes to systemic vascular deconditioning or vascular dysfunction contributes to decrements in muscular power remains to be determined. PMID:22966457

Heffernan, Kevin S.; Chale, Angela; Hau, Cynthia; Cloutier, Gregory J.; Phillips, Edward M.; Warner, Patrick; Nickerson, Heather; Reid, Kieran F.; Kuvin, Jeffrey T.; Fielding, Roger A.

2012-01-01

296

A novel vascular homing peptide strategy to selectively enhance pulmonary drug efficacy in pulmonary arterial hypertension.  

PubMed

A major limitation in the pharmacological treatment of pulmonary arterial hypertension (PAH) is the lack of pulmonary vascular selectivity. Recent studies have identified a tissue-penetrating homing peptide, CARSKNKDC (CAR), which specifically homes to hypertensive pulmonary arteries but not to normal pulmonary vessels or other tissues. Some tissue-penetrating vascular homing peptides have a unique ability to facilitate transport of co-administered drugs into the targeted cells/tissues without requiring physical conjugation of the drug to the peptide (bystander effect). We tested the hypothesis that co-administered CAR would selectively enhance the pulmonary vascular effects of i.v. vasodilators in Sugen5416/hypoxia/normoxia-exposed PAH rats. Systemically administered CAR was predominantly detected in cells of remodeled pulmonary arteries. Intravenously co-administered CAR enhanced pulmonary, but not systemic, effects of the vasodilators, fasudil and imatinib, in PAH rats. CAR increased lung tissue imatinib concentration in isolated PAH lungs without increasing pulmonary vascular permeability. Sublingual CAR was also effective in selectively enhancing the pulmonary vasodilation by imatinib and sildenafil. Our results suggest a new paradigm in the treatment of PAH, using an i.v./sublingual tissue-penetrating homing peptide to selectively augment pulmonary vascular effects of nonselective drugs without the potentially problematic conjugation process. CAR may be particularly useful as an add-on therapy to selectively enhance the pulmonary vascular efficacy of any ongoing drug treatment in patients with PAH. PMID:24401613

Toba, Michie; Alzoubi, Abdallah; O'Neill, Kealan; Abe, Kohtaro; Urakami, Takeo; Komatsu, Masanobu; Alvarez, Diego; Järvinen, Tero A H; Mann, David; Ruoslahti, Erkki; McMurtry, Ivan F; Oka, Masahiko

2014-02-01

297

Vascular endothelial growth factor coordinates islet innervation via vascular scaffolding.  

PubMed

Neurovascular alignment is a common anatomical feature of organs, but the mechanisms leading to this arrangement are incompletely understood. Here, we show that vascular endothelial growth factor (VEGF) signaling profoundly affects both vascularization and innervation of the pancreatic islet. In mature islets, nerves are closely associated with capillaries, but the islet vascularization process during embryonic organogenesis significantly precedes islet innervation. Although a simple neuronal meshwork interconnects the developing islet clusters as they begin to form at E14.5, the substantial ingrowth of nerve fibers into islets occurs postnatally, when islet vascularization is already complete. Using genetic mouse models, we demonstrate that VEGF regulates islet innervation indirectly through its effects on intra-islet endothelial cells. Our data indicate that formation of a VEGF-directed, intra-islet vascular plexus is required for development of islet innervation, and that VEGF-induced islet hypervascularization leads to increased nerve fiber ingrowth. Transcriptome analysis of hypervascularized islets revealed an increased expression of extracellular matrix components and axon guidance molecules, with these transcripts being enriched in the islet-derived endothelial cell population. We propose a mechanism for coordinated neurovascular development within pancreatic islets, in which endocrine cell-derived VEGF directs the patterning of intra-islet capillaries during embryogenesis, forming a scaffold for the postnatal ingrowth of essential autonomic nerve fibers. PMID:24574008

Reinert, Rachel B; Cai, Qing; Hong, Ji-Young; Plank, Jennifer L; Aamodt, Kristie; Prasad, Nripesh; Aramandla, Radhika; Dai, Chunhua; Levy, Shawn E; Pozzi, Ambra; Labosky, Patricia A; Wright, Christopher V E; Brissova, Marcela; Powers, Alvin C

2014-04-01

298

High permeability fracturing of gas wells  

SciTech Connect

The approach of Gas Research Institute (GRI) in its stimulation research has historically been one of evaluation, optimization and demonstration. First, evaluate industry practices from a theoretical and scientific perspective and determine if and why they really work. Then, determine how those practices can be improved and optimized. And finally, demonstrate the benefits of the improved methodologies or technologies. During the past decade, this approach has been successful in the case of coalbed methane, tight gas and shale gas research. Now GRI is applying the same idea to a relatively new technique: high permeability fracturing (HPF), commonly called frac packing, frac and pack or fracpacs. GRI has published three reports on the subject, one of which is highlighted in this article. This article focuses on material selection, treatment design and evaluation of high permeability fracturing, or frac packing, to optimize high permeability gas well completions.

Valko, P.P.; Oligney, R.E.; Economides, M.J. [Texas A and M Univ., College Station, TX (United States)

1998-01-01

299

Ablation of MMP9 gene ameliorates paracellular permeability and fibrinogen-amyloid beta complex formation during hyperhomocysteinemia.  

PubMed

Increased blood level of homocysteine (Hcy), called hyperhomocysteinemia (HHcy) accompanies many cognitive disorders including Alzheimer's disease. We hypothesized that HHcy-enhanced cerebrovascular permeability occurs via activation of matrix metalloproteinase-9 (MMP9) and leads to an increased formation of fibrinogen-?-amyloid (Fg-A?) complex. Cerebrovascular permeability changes were assessed in C57BL/6J (wild type, WT), cystathionine-?-synthase heterozygote (Cbs+/-, a genetic model of HHcy), MMP9 gene knockout (Mmp9-/-), and Cbs and Mmp9 double knockout (Cbs+/-/Mmp9-/-) mice using a dual-tracer probing method. Expression of vascular endothelial cadherin (VE-cadherin) and Fg-A? complex formation was assessed in mouse brain cryosections by immunohistochemistry. Short-term memory of mice was assessed with a novel object recognition test. The cerebrovascular permeability in Cbs+/- mice was increased via mainly the paracellular transport pathway. VE-cadherin expression was the lowest and Fg-A? complex formation was the highest along with the diminished short-term memory in Cbs+/- mice. These effects of HHcy were ameliorated in Cbs+/-/Mmp9-/- mice. Thus, HHcy causes activation of MMP9 increasing cerebrovascular permeability by downregulation of VE-cadherin resulting in an enhanced formation of Fg-A? complex that can be associated with loss of memory. These data may lead to the identification of new targets for therapeutic intervention that can modulate HHcy-induced cerebrovascular permeability and resultant pathologies. PMID:24865997

Muradashvili, Nino; Tyagi, Reeta; Metreveli, Naira; Tyagi, Suresh C; Lominadze, David

2014-09-01

300

Iron oxide nanoparticles induce human microvascular endothelial cell permeability through reactive oxygen species production and microtubule remodeling  

PubMed Central

Background Engineered iron nanoparticles are being explored for the development of biomedical applications and many other industry purposes. However, to date little is known concerning the precise mechanisms of translocation of iron nanoparticles into targeted tissues and organs from blood circulation, as well as the underlying implications of potential harmful health effects in human. Results The confocal microscopy imaging analysis demonstrates that exposure to engineered iron nanoparticles induces an increase in cell permeability in human microvascular endothelial cells. Our studies further reveal iron nanoparticles enhance the permeability through the production of reactive oxygen species (ROS) and the stabilization of microtubules. We also showed Akt/GSK-3? signaling pathways are involved in iron nanoparticle-induced cell permeability. The inhibition of ROS demonstrate ROS play a major role in regulating Akt/GSK-3? – mediated cell permeability upon iron nanoparticle exposure. These results provide new insights into the bioreactivity of engineered iron nanoparticles which can inform potential applications in medical imaging or drug delivery. Conclusion Our results indicate that exposure to iron nanoparticles induces an increase in endothelial cell permeability through ROS oxidative stress-modulated microtubule remodeling. The findings from this study provide new understandings on the effects of nanoparticles on vascular transport of macromolecules and drugs. PMID:19134195

Apopa, Patrick L; Qian, Yong; Shao, Rong; Guo, Nancy Lan; Schwegler-Berry, Diane; Pacurari, Maricica; Porter, Dale; Shi, Xianglin; Vallyathan, Val; Castranova, Vincent; Flynn, Daniel C

2009-01-01

301

The effect of heat on skin permeability  

PubMed Central

Although the effects of long exposure (? 1 s) to moderate temperatures (? 100 °C) have been well characterized, recent studies suggest that shorter exposure (< 1 s) to higher temperatures (> 100 °C) can dramatically increase skin permeability. Previous studies suggest that by keeping exposures short, thermal damage can be localized to the stratum corneum without damaging deeper tissue. Initial clinical trials have progressed to Phase II (see http://clinicaltrials.gov), which indicates the procedure can be safe. Because the effect of heating under these conditions has received little systematic or mechanistic study, we heated full-thickness skin, epidermis and stratum corneum samples from human and porcine cadavers to temperatures ranging from 100°C to 315°C for times ranging from 100 ms to 5 s. Tissue samples were analyzed using skin permeability measurements, differential scanning calorimetry, thermomechanical analysis, thermal gravimetric analysis, brightfield and confocal microscopy, and histology. Skin permeability was shown to be a very strong function of temperature and a less strong function of the duration of heating. At optimal conditions used in this study, transdermal delivery of calcein was increased up to 760-fold by rapidly heating the skin at high temperature. More specifically, skin permeability was increased (I) by a few fold after heating to approximately 100°C – 150°C, (II) by one to two orders of magnitude after heating to approximately 150°C – 250°C and (III) by three orders of magnitude after heating above 300°C. These permeability changes were attributed to (I) disordering of stratum corneum lipid structure, (II) disruption of stratum corneum keratin network structure and (III) decomposition and vaporization of keratin to create micron-scale holes in the stratum corneum, respectively. We conclude that heating the skin with short, high temperature pulses can increase skin permeability by orders of magnitude due to structural disruption and removal of stratum corneum. PMID:18455889

Park, Jung-Hwan; Lee, Jeong-Woo; Kim, Yeu-Chun; Prausnitz, Mark R.

2008-01-01

302

Vascular anomalies causing tracheoesophageal compression. Review of experience in children.  

PubMed

Two hundred four infants and children (mean age 13 months) have undergone operation for the relief of tracheoesophageal obstruction resulting from vascular anomalies. One hundred thirteen patients had complete vascular rings (group I), 61 with double aortic arch and 52 with right aortic arch with a left ligamentum. Nine patients had a pulmonary artery sling (group II), 71 had innominate artery compression (group III), and 11 had miscellaneous anomalies (group IV). Patients were admitted with respiratory distress, stridor, apnea, dysphagia, or recurrent respiratory infections. Diagnosis was established by barium esophagogram in group I; barium esophagogram, bronchoscopy, and computed tomography or angiography in group II; bronchoscopy in group III; and barium esophagogram or angiography in group IV. The operative approach was through a left thoracotomy in group I, II and IV (93% of these patients) and through a right thoracotomy for group III (96% of these patients). The operative mortality rate was 4.9% and there were seven late deaths (3.4%). There have been no operative deaths in patients with isolated vascular anomalies in the past 28 years. Follow-up data from 1 month to 20 years (mean 8.5 months) were available on 159 patients; 141 (92%) were essentially free of symptoms, and 12 (8%) had residual respiratory problems. Five of six patients in group II having a lung scan postoperatively had a patent left pulmonary artery. A strong index of suspicion is necessary to avoid the complications of vascular rings in children. Barium swallow is the best single diagnostic technique for patients with complete vascular rings. A bronchoscopic study is required to diagnose innominate artery compression. Angiograms or computed tomographic scans are used to confirm the diagnosis of pulmonary artery sling. Left thoracotomy provides excellent exposure for all vascular rings except the displaced innominate artery, for which a right thoracotomy is the best approach. PMID:2651808

Backer, C L; Ilbawi, M N; Idriss, F S; DeLeon, S Y

1989-05-01

303

Lunar magnetic permeability studies and magnetometer sensitivity  

NASA Technical Reports Server (NTRS)

A regression of quiet magnetic field components simultaneously measured by the two Explorer 35 magnetometers reveals uncertainties in effective sensitivity factors of up to a few percent in one or both of these instruments. Given this, the validity of previous lunar permeability studies based on Explorer 35/ALSEP regressions, wherein inferences are drawn from regression line slopes differing from unity by the order of one percent, is called into question. We emphasize the need to critically address the question of small deviations in magnetometer sensitivity factors from nominal values as a part of any two-magnetometer lunar permeability study.

King, J. H.; Ness, N. F.

1977-01-01

304

Magnetic permeability measurements and a lunar core  

NASA Technical Reports Server (NTRS)

Measurements of the magnetic field induced in the moon while it is in the geomagnetic tail lobes have been interpreted in terms of lunar magnetic permeability due to free iron content; such studies ignored the possibility that a highly conducting lunar core (Fe or FeS) would exclude magnetic fields with an apparent diamagnetic effect. Using lunar chemical and thermal models to determine plausible limits of magnetic permeability, we interpret measurements of the induced moment. The maximum likely radius of a lunar core is 580 km. Subsatellite and ALSEP measurements of the induced field are in disagreement. Resolving the differences is critical to determining whether a core could or does exist.

Goldstein, B. E.; Phillips, R. J.; Russell, C. T.

1976-01-01

305

CENDI Indexing Workshop  

NASA Technical Reports Server (NTRS)

The CENDI Indexing Workshop held at NASA Headquarters, Two Independence Square, 300 E Street, Washington, DC, on September 21-22, 1994 focused on the following topics: machine aided indexing, indexing quality, an indexing pilot project, the MedIndEx Prototype, Department of Energy/Office of Scientific and Technical Information indexing activities, high-tech coding structures, category indexing schemes, and the Government Information Locator Service. This publication consists mostly of viewgraphs related to the above noted topics. In an appendix is a description of the Government Information Locator Service.

1994-01-01

306

Vascularization strategies for bone regeneration.  

PubMed

The functional regeneration of thick vascularized tissues such as bone and muscle is complicated by the large volume of lost tissue, challenging biomechanical environment, and the need to reproduce the highly organized structure of both the native tissue extracellular matrix and its vascular support system. Stem cell or progenitor cell delivery approaches, for example, continue to be plagued by low viability and engraftment in part due to the initial absence of a vascular supply. Recognition of diffusion limitations in thick tissues has prompted regenerative strategies that seek to accelerate establishment of a functional vasculature. The successful design of robust regeneration strategies for these challenging clinical scenarios will rely on a thorough understanding of interactions between construct design parameters and host biological and biomechanical factors. Here, we discuss the critical role of vascularization in normal bone tissue homeostasis and repair, vascular network adaptation to the local biomechanical environment, and the future directions of revascularization approaches being developed and integrated with bone regeneration strategies. PMID:24468975

Krishnan, Laxminarayanan; Willett, Nick J; Guldberg, Robert E

2014-02-01

307

Human vascular smooth muscle cells inhibit platelet aggregation when incubated with glyceryl trinitrate: evidence for generation of nitric oxide.  

PubMed Central

1. The effect on platelet aggregation of glyceryl trinitrate in the presence of cultured vascular smooth muscle cells was determined turbidometrically. U46619 (a thromboxane mimetic) was used as agonist and experiments were performed in the presence of aspirin. Inorganic nitrite production from glyceryl trinitrate by vascular smooth muscle cells was also measured, to provide an indirect index of nitric oxide synthesis. 2. The combination of vascular smooth muscle cells together with glyceryl trinitrate, at concentrations that had little effect individually, profoundly inhibited platelet aggregation. 3. The inhibitory effect on platelet aggregation of vascular smooth muscle cells together with glyceryl trinitrate was markedly attenuated by haemoglobin, an inhibitor of nitric oxide. 4. These results show that vascular smooth muscle cells inhibit platelet aggregation when exposed to glycerol trinitrate and suggest that this is due to generation of nitric oxide from glyceryl trinitrate by vascular smooth muscle. PMID:1906768

Benjamin, N.; Dutton, J. A.; Ritter, J. M.

1991-01-01

308

Role of FAK in S1P-Regulated Endothelial Permeability  

PubMed Central

The vascular endothelium serves as a semi-selective barrier between the circulating contents of the blood and the tissues through which they flow. Disruption of this barrier results in significant organ dysfunction during devastating inflammatory syndromes such as sepsis and acute lung injury (ALI). Sphingosine 1-phosphate (S1P) is an endogenous lipid regulator of endothelial permeability that produces potent barrier enhancement via actin and junctional protein rearrangement and resultant cytoskeletal changes. A key effector protein in this S1P response is focal adhesion kinase (FAK), a highly conserved cytoplasmic tyrosine kinase involved in the engagement of integrins and assembly of focal adhesions (FA) through the catalysis of multiple downstream signals. After stimulation by S1P, endothelial FAK undergoes specific tyrosine phosphorylation that results in activation of the kinase and dynamic interactions with other effector molecules to improve the endothelial barrier. FAK participates in peripheral actin cytoskeletal rearrangement as well as cell-matrix (FA) and cell-cell (adherens junction) junctional complex strengthening that combine to decrease vascular permeability. This review summarizes the current knowledge of the role of FAK in mediating enhanced endothelial barrier function by S1P. PMID:21925517

Belvitch, Patrick; Dudek, Steven M.

2013-01-01

309

Adverse Outcome Pathways for Embryonic Vascular Disruption and Alternative Methods to Identify Chemical Vascular Disruptor  

EPA Science Inventory

Chemically induced vascular toxicity during embryonic development can result in a wide range of adverse prenatal outcomes. We used information from genetic mouse models linked to phenotypic outcomes and a vascular toxicity knowledge base to construct an embryonic vascular disrupt...

310

Hormone interactions during vascular development.  

PubMed

Vascular tissue in plants is unique due to its diverse and dynamic cellular patterns. Signals controlling vascular development have only recently started to emerge through biochemical, genetic, and genomic approaches in several organisms, such as Arabidopsis, Populus, and Zinnia. These signals include hormones (auxin, brassinosteroids, and cytokinins, in particular), other small regulatory molecules, their transporters, receptors, and various transcriptional regulators. In recent years it has become apparent that plant growth regulators rarely act alone, but rather their signaling pathways are interlocked in complex networks; for example, polar auxin transport (PAT) regulates vascular development during various stages and an emerging theme is its modulation by other growth regulators, depending on the developmental context. Also, several synergistic or antagonistic interactions between various growth regulators have been described. Furthermore, shoot-root interactions appear to be important for this signal integration. PMID:18654740

Dettmer, Jan; Elo, Annakaisa; Helariutta, Ykä

2009-03-01

311

Vascularization Strategies for Tissue Engineering  

PubMed Central

Tissue engineering is currently limited by the inability to adequately vascularize tissues in vitro or in vivo. Issues of nutrient perfusion and mass transport limitations, especially oxygen diffusion, restrict construct development to smaller than clinically relevant dimensions and limit the ability for in vivo integration. There is much interest in the field as researchers have undertaken a variety of approaches to vascularization, including material functionalization, scaffold design, microfabrication, bioreactor development, endothelial cell seeding, modular assembly, and in vivo systems. Efforts to model and measure oxygen diffusion and consumption within these engineered tissues have sought to quantitatively assess and improve these design strategies. This review assesses the current state of the field by outlining the prevailing approaches taken toward producing vascularized tissues and highlighting their strengths and weaknesses. PMID:19496677

Lovett, Michael; Lee, Kyongbum; Edwards, Aurelie

2009-01-01

312

Standardized Definitions for Hemodialysis Vascular Access  

PubMed Central

Vascular access dysfunction is one of the leading causes of morbidity and mortality among end-stage renal disease patients 1,2. Vascular access dysfunction exists in all 3 types of available accesses: arteriovenous fistulas, arteriovenous grafts, and tunneled catheters. In order to improve clinical research and outcomes in hemodialysis access dysfunction, the development of a multidisciplinary network of collaborative investigators with various areas of expertise, and common standards for terminology and classification in all vascular access types is required. The North American Vascular Access Consortium (NAVAC) is a newly formed multidisciplinary and multicenter network of experts in the area of hemodialysis vascular access, who include nephrologists and interventional nephrologists from the United States and Canada with: (1) a primary clinical and research focus in hemodialysis vascular access dysfunction, (2) national and internationally recognized experts in vascular access, and (3) a history of productivity measured by peer-reviewed publications and funding among members of this consortium. The consortium’s mission is to improve the quality and efficiency in vascular access research, and impact the research in the area of hemodialysis vascular access by conducting observational studies and randomized controlled trials. The purpose of the consortium’s initial manuscript is to provide working and standard vascular access definitions relating to (1) epidemiology, (2) vascular access function, (3) vascular access patency, and (4) complications in vascular accesses relating to each of the vascular access types. PMID:21906166

Lee, Timmy; Mokrzycki, Michele; Moist, Louise; Maya, Ivan; Vazquez, Miguel; Lok, Charmaine

2014-01-01

313

Use of sulodexide in patients with peripheral vascular disease  

PubMed Central

Sulodexide is a highly purified glycosaminoglycan containing a combination of heparan sulfate with affinity for antithrombin III and dermatan sulfate with affinity for heparin cofactor II. This antithrombotic and antithrombin activity is of great pharmacologic interest and makes sulodexide a suitable drug for the prophylaxis and treatment of arterial and venous peripheral diseases. In arterial pathology, changes in the Winsor Index, improvement in peripheral blood flow, and reduction in pain-free walking distance confirm that treatment with oral sulodexide is effective. Lipid components linked to the genesis of peripheral vascular processes, including triglycerides, total cholesterol, and low-density lipoprotein fractions, as well as plasma and blood viscosity, are reduced by the administration of sulodexide, whereas the high-density lipoprotein fraction increases. Sulodexide inhibits aggregation and adhesion of platelets at the level of the vascular wall, reduces plasma fibrinogen concentrations, reduces plasminogen activator inhibitor-1, and increases tissue plasminogen activator, as well as systemic fibrinolytic and thrombolytic activity, thereby demonstrating efficacy in the treatment of thromboembolic disease. There is no interaction between sulodexide and other drugs used as long-term treatment for peripheral vascular disease. It is well tolerated, and the adverse reactions described after oral administration are related mainly to transient gastrointestinal intolerance, ie, nausea, dyspepsia, and minor bowel symptoms. Sulodexide may become the treatment of choice when dealing with vascular diseases and their complications, as well as for the prevention of venous thromboembolic disease, being particularly indicated in elderly patients, due to its good tolerability and ease of management. PMID:22282689

Lasierra-Cirujeda, J; Coronel, P; Aza, MJ; Gimeno, M

2010-01-01

314

Use of sulodexide in patients with peripheral vascular disease.  

PubMed

Sulodexide is a highly purified glycosaminoglycan containing a combination of heparan sulfate with affinity for antithrombin III and dermatan sulfate with affinity for heparin cofactor II. This antithrombotic and antithrombin activity is of great pharmacologic interest and makes sulodexide a suitable drug for the prophylaxis and treatment of arterial and venous peripheral diseases. In arterial pathology, changes in the Winsor Index, improvement in peripheral blood flow, and reduction in pain-free walking distance confirm that treatment with oral sulodexide is effective. Lipid components linked to the genesis of peripheral vascular processes, including triglycerides, total cholesterol, and low-density lipoprotein fractions, as well as plasma and blood viscosity, are reduced by the administration of sulodexide, whereas the high-density lipoprotein fraction increases. Sulodexide inhibits aggregation and adhesion of platelets at the level of the vascular wall, reduces plasma fibrinogen concentrations, reduces plasminogen activator inhibitor-1, and increases tissue plasminogen activator, as well as systemic fibrinolytic and thrombolytic activity, thereby demonstrating efficacy in the treatment of thromboembolic disease. There is no interaction between sulodexide and other drugs used as long-term treatment for peripheral vascular disease. It is well tolerated, and the adverse reactions described after oral administration are related mainly to transient gastrointestinal intolerance, ie, nausea, dyspepsia, and minor bowel symptoms. Sulodexide may become the treatment of choice when dealing with vascular diseases and their complications, as well as for the prevention of venous thromboembolic disease, being particularly indicated in elderly patients, due to its good tolerability and ease of management. PMID:22282689

Lasierra-Cirujeda, J; Coronel, P; Aza, Mj; Gimeno, M

2010-01-01

315

Vascular gene expression: a hypothesis  

PubMed Central

The phloem is the conduit through which photoassimilates are distributed from autotrophic to heterotrophic tissues and is involved in the distribution of signaling molecules that coordinate plant growth and responses to the environment. Phloem function depends on the coordinate expression of a large array of genes. We have previously identified conserved motifs in upstream regions of the Arabidopsis genes, encoding the homologs of pumpkin phloem sap mRNAs, displaying expression in vascular tissues. This tissue-specific expression in Arabidopsis is predicted by the overrepresentation of GA/CT-rich motifs in gene promoters. In this work we have searched for common motifs in upstream regions of the homologous genes from plants considered to possess a “primitive” vascular tissue (a lycophyte), as well as from others that lack a true vascular tissue (a bryophyte), and finally from chlorophytes. Both lycophyte and bryophyte display motifs similar to those found in Arabidopsis with a significantly low E-value, while the chlorophytes showed either a different conserved motif or no conserved motif at all. These results suggest that these same genes are expressed coordinately in non-vascular plants; this coordinate expression may have been one of the prerequisites for the development of conducting tissues in plants. We have also analyzed the phylogeny of conserved proteins that may be involved in phloem function and development. The presence of CmPP16, APL, FT, and YDA in chlorophytes suggests the recruitment of ancient regulatory networks for the development of the vascular tissue during evolution while OPS is a novel protein specific to vascular plants. PMID:23882276

Martinez-Navarro, Angelica C.; Galvan-Gordillo, Santiago V.; Xoconostle-Cazares, Beatriz; Ruiz-Medrano, Roberto

2013-01-01

316

Hydraulic testing of low-permeability formations  

Microsoft Academic Search

In recent years, the study of low-permeability geological formations has undergone considerable development. This is mainly due to the use of natural geological barriers to confine waste disposals, preventing leaking water from bringing contaminants into contact with the biosphere and the groundwater resources.In that context, the Spanish Geological Survey (IGME, Spanish acronym), supported by the National Radioactive Waste Management Agency

Miguel Mejías; Philippe Renard; Damian Glenz

2009-01-01

317

Permeable pavement research ? Edison, New Jersey  

EPA Science Inventory

These are the slides for the New York City Concrete Promotional Council Pervious Concrete Seminar presentation. The basis for the project, the monitoring design and some preliminary monitoring data from the permeable pavement parking lot at the Edison Environmental Center are pre...

318

SINGLE-INTERVAL GAS PERMEABILITY ESTIMATION  

EPA Science Inventory

Single-interval, steady-steady-state gas permeability testing requires estimation of pressure at a screened interval which in turn requires measurement of friction factors as a function of mass flow rate. Friction factors can be obtained by injecting air through a length of pipe...

319

Impedance and initial magnetic permeability of gadolinium  

Microsoft Academic Search

In the present work we report on measurements of the complex impedance and the magnetoimpedance of a textured sample of gadolinium metal. The preferential c-axis orientation of the Gd hexagonal structure is perpendicular to the long axis of the sample. From the experimental data, the complex initial magnetic permeability, ?=??+i??, was obtained as a function of temperature and frequency of

G. L. F. Fraga; P. Pureur; L. P. Cardoso

2010-01-01

320

Impedance and initial magnetic permeability of gadolinium  

Microsoft Academic Search

In the present work we report on measurements of the complex impedance and the magnetoimpedance of a textured sample of gadolinium metal. The preferential c -axis orientation of the Gd hexagonal structure is perpendicular to the long axis of the sample. From the experimental data, the complex initial magnetic permeability, mu=mu'+imu'', was obtained as a function of temperature and frequency

G. L. F. Fraga; P. Pureur; L. P. Cardoso

2010-01-01

321

Waveguide miniaturization using uniaxial negative permeability metamaterial  

Microsoft Academic Search

A rectangular waveguide filled with anisotropic uniaxial metamaterial with transversal negative effective permeability is investigated both theoretically and experimentally. It is shown that such a waveguide supports propagation of the backward wave below the cutoff frequency, thus, it can be considered as a dual of the ordinary waveguide. The transversal dimension of this waveguide can be arbitrarily smaller than half

Silvio Hrabar; Juraj Bartolic; Zvonimir Sipus

2005-01-01

322

Composition for selectively reducing subterranean formation permeability  

Microsoft Academic Search

This patent describes a process for selectively reducing the water permeability of a hydrocarbon-containing subterranean formation. It comprises contacting an inorganic crosslinking agent with an aqueous solution comprising at least some cationic polyacrylamide to form a composition; injecting the composition into at least a portion of the subterranean formation, wherein the composition forms a visible gel in at least a

R. D. Hutchins; H. T. Dovan

1992-01-01

323

Cellular Automata Model of Membrane Permeability  

Microsoft Academic Search

A cellular automata model of a semi-permeable membrane has been created separating two compartments of water. Several cells encrypting the properties of a polar solute are located near the membrane surface in one compartment. These solute cells influence the preferential diffusion of water cells from the other compartment to enter the membrane. This simulation of the osmotic effect is found

Lemont B. Kier; Chao-Kun Cheng

1997-01-01

324

Permeability Measurements in Carbon-Epoxy Composites  

NASA Technical Reports Server (NTRS)

To determine the permeability of the composite feedline, that is proposed to be used in the X-33 Reusable Launch Vehicle (RLV), three 8 x 8-in. coupons were constructed. Two of the coupons were layed-up with 4 plies of plain weave prepreg [0/90, plus or minus 45, plus or minus 45, 0/90] and the other one layed-up with 4 plies of unidirectional prepreg [0, 90, 90, 0]. The coupons were vacuumed bagged and cured to manufactures specifications. The coupons were then placed in an apparatus to test for permeability. Nitrogen gas was used to permeate through the coupons at a pressure of 5 psig. A manometer was placed on the opposite side of the coupons and was used to measure the height of the fluid with respect to time. From this data the mass flow rate of the gas could be calculated since the area of the manometer and the density of the gas is known. The results of the test are given. The permeability constant was calculated using Darcy's law, which related the pressure drop, flow rate of the permeating gas and resistance to flow through the coupon created. To put the results into prospective the permeability of sand stone and granite is 1E-15 and 1E-20 respectively.

Zdenek, Michael J.

1999-01-01

325

Porosity and permeability of foamed concrete  

Microsoft Academic Search

A study has been undertaken to investigate the effects, on the properties of foamed concrete, of replacing large volumes of cement (up to 75% by weight) with both classified and unclassified fly ash. This paper reports only on the results of permeability and porosity measured up to an age of 1 year on well-cured concretes. Porosity was found to be

E. P Kearsley; P. J Wainwright

2001-01-01

326

Atlas of Tennessee Vascular Plants  

NSDL National Science Digital Library

The Austin Peay State University Center for Field Biology and the University of Tennessee Herbarium have collaborated to produce the Atlas of Tennessee Vascular Plants. Species distribution maps are provided in alphabetical order (scientific name) for Pteridophytes, Gymnosperms, Monocots, and Dicots in the western, middle, and eastern parts of the state. Each map is color-coded by abundance, and highlights distribution across counties. Currently under construction, two additional sections will soon include a Database of Tennessee Vascular Plants and links to the Bryophyte Herbarium, among other features.

327

Transglutaminases in Vascular Biology: Relevance for Vascular Remodeling and Atherosclerosis  

Microsoft Academic Search

The transglutaminase (Tgase) family consists of nine known members of whom at least three are expressed in the vascular system: type 1 Tgase, type 2 Tgase and factor XIII. The cross-linking of proteins is a characteristic feature of Tgases, of well-known importance for stabilizing the blood clot and providing mechanical strength to tissues. However, recent data suggest that Tgases play

Erik N. T. P. Bakker; Adrian Pistea; Ed VanBavel

2008-01-01

328

Vascular injury, vascular healing, hypertension and the renin system  

Microsoft Academic Search

Alterations in structure and function of blood vessels that occur in hypertensive patients and in experimental hypertensive models may contribute to blood pressure elevation and to the complications of hypertension. Angiotensin II may influence the vasculature in hypertension through its effects on the atherogenic process and on hypertensive vascular disease per se. The actions of angiotensin II on inflammation, smooth

E. L. Schiffrin

2000-01-01

329

Differential apicobasal VEGF signaling at vascular blood-neural barriers.  

PubMed

The vascular endothelium operates in a highly polarized environment, but to date there has been little exploration of apicobasal polarization of its signaling. We show that VEGF-A, histamine, IGFBP3, and LPA trigger unequal endothelial responses when acting from the circulation or the parenchymal side at blood-neural barriers. For VEGF-A, highly polarized receptor distribution contributed to distinct signaling patterns: VEGFR2, which was found to be predominantly abluminal, mediated increased permeability via p38; in contrast, luminal VEGFR1 led to Akt activation and facilitated cytoprotection. Importantly, such differential apicobasal signaling and VEGFR distribution were found in the microvasculature of brain and retina but not lung, indicating that endothelial cells at blood-neural barriers possess specialized signaling compartments that assign different functions depending on whether an agonist is tissue or blood borne. PMID:25175707

Hudson, Natalie; Powner, Michael B; Sarker, Mosharraf H; Burgoyne, Thomas; Campbell, Matthew; Ockrim, Zoe K; Martinelli, Roberta; Futter, Clare E; Grant, Maria B; Fraser, Paul A; Shima, David T; Greenwood, John; Turowski, Patric

2014-09-01

330

Dow Jones Internet Indexes  

NSDL National Science Digital Library

Dow Jones Indexes has created the Dow Jones Internet Index (DJII) to bring "an ordered perspective" to "the seeming chaos of Internet stocks." The new index includes companies that generate a minimum of 50 percent of their revenues from the Internet. Complete documentation of DJII components, data, historical values, and news are provided on-site.

331

Aldosterone modulates endothelial permeability and endothelial nitric oxide synthase activity by rearrangement of the actin cytoskeleton.  

PubMed

Aldosterone (Aldo) is involved in vascular remodeling and inflammation; however, the mechanisms are imperfectly defined. We hypothesized that Aldo alters endothelial integrity and modifies paracellular permeability. Human umbilical vein endothelial cells were exposed to Aldo (10(-9) mol/L) and alterations in paracellular permeability, assembly of tight and adherens junctions and activation of intracellular signaling pathways were determined. Aldo increased endothelial permeability for molecules ? 70 kDa within 60 minutes. A transient loss of cortical actin with formation of actin stress fibers and disruption of continuous adherens and tight junction strands accompanied these changes. Mineralocorticoid receptor blockade, inhibition of RhoA, or disruption of extracellular-regulated protein kinase1/2 signaling pathways attenuated the Aldo-related effects. Moreover, Aldo-induced cytoskeletal rearrangement led to rapid dephosphorylation of protein kinase B and subsequent deactivation of endothelial nitric oxide synthase. Ex vivo tracer flux experiments with Evans blue-conjugated albumin demonstrated a concordant response to Aldo in freshly isolated umbilical arteries. Furthermore, low-dose cortisol (3 × 10(-10) to 3 × 10(-9) mol/L) mimics the effect of Aldo on endothelial integrity, and Aldo, by upregulating11?-hydroxysteroid dehydrogenase type 2, might even aggravate this deleterious effect of low-dose cortisol. We suggest that these mechanisms may contribute to the vasculopathy induced by inappropriate mineralocorticoid receptor activation. PMID:23213194

Kirsch, Torsten; Beese, Michaela; Wyss, Kristin; Klinge, Uwe; Haller, Hermann; Haubitz, Marion; Fiebeler, Anette

2013-02-01

332

Ionic Permeability of Thin Lipid Membranes  

PubMed Central

Ultrathin (black) lipid membranes were made from sheep red cell lipids dissolved in n-decane. The presence of aliphatic alcohols in the aqueous solutions bathing these membranes produced reversible changes in the ionic permeability, but not the osomotic permeability. Heptanol (8 mM), for example, caused the membrane resistance (Rm) to decrease from >108 to about 105 ohm-cm2 and caused a marked increase in the permeability to cations, especially potassium. In terms of ionic transference numbers, deduced from measurements of the membrane potential at zero current, Tcat/TCl increased from about 6 to 21 and TK/TNa increased from about 3 to 21. The addition of long-chain (C8ndash;C10) alcohols to the lipid solutions from which membranes were made produced similar effects on the ionic permeability. A plot of log Rm vs. log alcohol concentration was linear over the range of maximum change in Rm, and the slope was -3 to -5 for C2 through C7 alcohols, suggesting that a complex of several alcohol molecules is responsible for the increase in ionic permeability. Membrane permselectivity changed from cationic to anionic when thorium or ferric iron (10-4 M) was present in the aqueous phase or when a secondary amine (Amberlite LA-2) was added to the lipid solutions from which membranes were made. When membranes containing the secondary amine were exposed to heptanol, Rm became very low (103–104 ohm-cm2) and the membranes became perfectly anion-selective, developing chloride diffusion potentials up to 150 mv. PMID:5535355

Gutknecht, John; Tosteson, D. C.

1970-01-01

333

Automated system for permeability and electrical conductivity of low-permeability reservoir rock  

NASA Astrophysics Data System (ADS)

An automated laboratory control and measurement system for liquid permeability and electrical conductivity of low permeability reservoir rock as a function of confining pressure has been contructed and tested. The system is controlled by a deskton computer with digital I/0, ADC and IEEE-488 interfaces. Computer programs and flow charts are presented for the automated system and for application of portions of the system to other laboratory experiments.

Jennings, J. B.; Raible, C. J.; Carroll, H. B., Jr.

1982-07-01

334

Permeability anisotropy and resistivity anisotropy of mechanically compressed mudrocks  

E-print Network

Permeability anisotropy (the ratio of the horizontal to vertical permeability) is an important parameter used in sedimentary basin models and geotechnical design to model fluid flow, locate hydrocarbon reserves and estimate ...

Adams, Amy Lynn

2014-01-01

335

Moisture Durability of Vapor Permeable Insulating Sheathing (Fact Sheet)  

SciTech Connect

In this project, Building America team Building Science Corporation researched some of the ramifications of using exterior, vapor permeable insulation on retrofit walls with vapor permeable cavity insulation. Retrofit strategies are a key factor in reducing exterior building stock consumption.

Not Available

2013-10-01

336

OK8a.o o o I?. Permeability, Porosity,  

E-print Network

OK8a.o o o I?. Permeability, Porosity, Dispersion-, Diffusion-, and Sorption Characteristics, POROSITY, DISPERSION1 -, DIFFUSION-, AND SORPTION CHARACTERISTICS OF CHALK SAMPLES FROM ERSLEV, MORS in order to establish permeabilities, porosities, dispersion-, diffusion-, and sorption characteristics

337

Perioperative assessment in vascular surgery  

SciTech Connect

This book contains 21 selections. Some of the titles are: The use of ultrasound and computerized tomographic scanning in the diagnosis of vascular pathology; Ancillary techniques in diagnostic angiography; Pre-bypass operative arteriography; Perioperative assessment of in situ bypass grafts; and Early and late evaluation of postoperative carotid restenosis and occlusion.

Flanigan, D.P.

1987-01-01

338

Peripheral vascular imaging and intervention  

SciTech Connect

This reference addresses the entire clinical approach to the vascular system from the diagnosis of pathology to surgery or interventional radiological management. All diagnostic imaging modalities currently available are included with specific information on how to interpret various results. It features discussions of the latest therapeutic techniques, including laser angioplasty, intravascular stents, and transluminal embolization.

Kim, D. (Division of Vascular and Interventional Radiology, Dept. of Radiology, Beth Israel Hospital, Boston, MA (US)); Orron, D.E. (Dept. of Radiology, Beth Israel Hospital, Boston MA (US))

1990-01-01

339

Vascular cognitive impairment in dementia.  

PubMed

Vascular risk factors and cerebrovascular disease are common causes of dementia. Shared risk factors for vascular dementia and Alzheimer's disease, as well as frequent coexistence of these pathologies in cognitively impaired older people, suggests convergence of the aetiology, prevention and management of the commonest dementias affecting older people. In light of this understanding, the cognitive impairment associated with cerebrovascular disease is an increasingly important and recognised area of the medicine of older people. Although the incidence of cerebrovascular events is declining in many populations, the overall burden associated with brain vascular disease will continue to increase associated with population ageing. A spectrum of cognitive disorders related to cerebrovascular disease is now recognised. Cerebrovascular disease in older people is associated with specific clinical and imaging findings. Although prevention remains the cornerstone of management, the diagnosis of brain vascular disease is important because of the potential to improve clinical outcomes through clear diagnosis, enhanced control of risk factors, lifestyle interventions and secondary prevention. Specific pharmacological intervention may also be indicated for some patients with cognitive impairment and cerebrovascular disease. However the evidence base to guide intervention remains relatively sparse. PMID:25011396

Etherton-Beer, Christopher D

2014-10-01

340

VASCULAR CALCIFICATION IN DIALYSIS PATIENTS  

Microsoft Academic Search

A b s t r a c t: Renal osteodystrophy, vascular disease and mortality are believed to be linked in patients with chronic kidney disease (CKD), although to date most of the evidence is based only on statistical associations. The precise pathophysiology of vascu- lar calcification in end stagerenal disease (ESRD) is unknown, but risk factors include age, hypertension, time

341

Network theory in vascular laboratories  

Microsoft Academic Search

The medical community is a network of physicians, nurses, technologists, patients, insurance companies, and administrators who interact with each other to provide patient care. Within this vast network is the vascular laboratory. Using actor network theory described by Stanley Milgram, Bruno Latour, and Albert-László Barabási I plan to identify different factors called actors that play a pivotal role in the

Kathleen Greene

2005-01-01

342

Renal Vascular Resistance in Sepsis  

Microsoft Academic Search

Aims: To assess changes in renal vascular resistance (RVR) in human and experimental sepsis and to identify determinants of RVR. Methods: We performed a systematic interrogation of two electronic reference libraries using specific search terms. Subjects were animals and patients involved in experimental and human studies of sepsis and septic acute renal failure, in which the RVR was assessed. We

Christoph Langenberg; Rinaldo Bellomo; Clive N. May; Moritoki Egi; Li Wan; Stanislao Morgera

2006-01-01

343

The relationships of vascular plants.  

PubMed Central

Recent phylogenetic research indicates that vascular plants evolved from bryophyte-like ancestors and that this involved extensive modifications to the life cycle. These conclusions are supported by a range of systematic data, including gene sequences, as well as evidence from comparative morphology and the fossil record. Within vascular plants, there is compelling evidence for two major clades, which have been termed lycophytes (clubmosses) and euphyllophytes (seed plants, ferns, horsetails). The implications of recent phylogenetic work are discussed with reference to life cycle evolution and the interpretation of stratigraphic inconsistencies in the early fossil record of land plants. Life cycles are shown to have passed through an isomorphic phase in the early stages of vascular plant evolution. Thus, the gametophyte generation of all living vascular plants is the product of massive morphological reduction. Phylogenetic research corroborates earlier suggestions of a major representational bias in the early fossil record. Mega-fossils document a sequence of appearance of groups that is at odds with that predicted by cladogram topology. It is argued here that the pattern of appearance and diversification of plant megafossils owes more to changing geological conditions than to rapid biological diversification. PMID:10905613

Kenrick, P

2000-01-01

344

Permeability-porosity relationships in sedimentary rocks  

USGS Publications Warehouse

In many consolidated sandstone and carbonate formations, plots of core data show that the logarithm of permeability (k) is often linearly proportional to porosity (??). The slope, intercept, and degree of scatter of these log(k)-?? trends vary from formation to formation, and these variations are attributed to differences in initial grain size and sorting, diagenetic history, and compaction history. In unconsolidated sands, better sorting systematically increases both permeability and porosity. In sands and sandstones, an increase in gravel and coarse grain size content causes k to increase even while decreasing ??. Diagenetic minerals in the pore space of sandstones, such as cement and some clay types, tend to decrease log(k) proportionately as ?? decreases. Models to predict permeability from porosity and other measurable rock parameters fall into three classes based on either grain, surface area, or pore dimension considerations. (Models that directly incorporate well log measurements but have no particular theoretical underpinnings from a fourth class.) Grain-based models show permeability proportional to the square of grain size times porosity raised to (roughly) the fifth power, with grain sorting as an additional parameter. Surface-area models show permeability proportional to the inverse square of pore surface area times porosity raised to (roughly) the fourth power; measures of surface area include irreducible water saturation and nuclear magnetic resonance. Pore-dimension models show permeability proportional to the square of a pore dimension times porosity raised to a power of (roughly) two and produce curves of constant pore size that transgress the linear data trends on a log(k)-?? plot. The pore dimension is obtained from mercury injection measurements and is interpreted as the pore opening size of some interconnected fraction of the pore system. The linear log(k)-?? data trends cut the curves of constant pore size from the pore-dimension models, which shows that porosity reduction is always accompanied by a reduction in characteristic pore size. The high powers of porosity of the grain-based and surface-area models are required to compensate for the inclusion of the small end of the pore size spectrum.

Nelson, Philip, H.

1994-01-01

345

Balsalazine decreases intestinal mucosal permeability of dextran sulfate sodium-induced colitis in mice  

PubMed Central

Aim: To investigate the effect of balsalazine treatment on intestinal mucosal permeability in dextran sulfate sodium (DSS)-induced colitis and to determine the mechanism of the balsalazine-induced changes. Methods: Experimental colitis was induced in C57BL/6J mice by the administration of 5% DSS. Balsalazine was administered intragastrically at doses of 42, 141, and 423 mg/kg. The disease activity index (DAI) score was evaluated and colon tissue was collected for the assessment of histological changes. The amount of malondialdehyde (MDA) in the colon was determined, along with the activity of myeloperoxidase (MPO), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Mucosa from the small intestine was collected to determine the levels of tumor necrosis factor (TNF)-? and interferon (IFN)-?. The mucosa was ultrastructurally examined with transmission electron microscopy and intestinal permeability was assayed using Evans blue. Results: Balsalazine was found to reduce the DAI score and the histological index (HI) score, decrease the MDA content and the activity of MPO, and increase the activity of SOD and GSH-Px in colitis mice. At the same time, balsalazine ameliorated microvillus and tight junction structure, resulting in a decrease in the amount of Evans blue permeating into the intestinal wall and the levels of TNF-? and IFN-? in colitis mice. Conclusion: In colitis mice, the anti-colitis effect of balsalazine results in a decrease in intestinal mucosal permeability. The mechanism of this effect is partly associated with balsalazine's antioxidative and anti-inflammatory effects. PMID:19575002

Liu, Xiao-chang; Mei, Qiao; Xu, Jian-ming; Hu, Jing

2009-01-01

346

Recent insights into the role of prostanoids in atherosclerotic vascular disease.  

PubMed

Atherosclerosis is characterized by chronic inflammation and enrichment of inflammatory cells in the vessel wall. Acute inflammation can lead to damaged endothelium triggering the coagulation cascade and thrombus formation. Likewise, the clotting cascade may elicit an inflammatory response. The vascular endothelium regulates vascular tone, permeability, inflammation, thrombosis, and coagulation. Dysfunction of the vascular endothelium can promote atherosclerotic disease processes. Prostanoids (prostaglandins, thromboxane, and prostacyclin) have been established as inflammatory mediators in vascular endothelial function and there continues to be growing insights into their role in atherosclerotic disease. This review examines the role of prostanoids as paracrine inflammatory mediators of atherosclerotic vascular disease, highlighting the relevant physiology of eicosanoid production and endothelial dysfunction. We consider the role of prostanoids in systemic diseases associated with high cardiovascular morbidity and mortality, including diabetes mellitus, coronary artery disease, peripheral arterial disease, rheumatologic disorders, and dyslipidemia. We present emerging evidence that cardio-protective and lipid lowering medications, such as irbesartan and simvastatin may exert their effects via prostanoid mediated pathways. Both serum and urinary prostanoids may be utilized as diagnostic predictors of disease; for example 8-iso-PGF(2alpha) in the serum has recently been reported as an independent predictor of symptomatic peripheral arterial disease. In addition, we discuss current recommendations on established therapeutic uses of prostanoids for atherosclerotic diseases, such as the use of PGE(1) for the treatment of peripheral arterial disease. Finally, we investigate original therapeutic modalities of various prostanoids involved in the aforementioned diseases. PMID:17073704

Reiss, Allison B; Edelman, Sari D

2006-10-01

347

Development and Physical Characteristics of Novel Zero-Porosity Vascular Graft "Triplex®"  

PubMed Central

We developed a novel large-diameter graft “Triplex®” that uses a non-biodegradable material as a coating material. This time, in order to demonstrate the physical properties of Triplex® grafts, we conducted physical tests in accordance with the international guidelines, using the collagen coated vascular grafts (Hemashield, Boston Scientific, Natick, Massachusetts, USA) as the controls. The grafts were tested with regard to strength (burst strength, circumferential tensile strength, longitudinal tensile strength), suture retention strength, integral water permeability, water leakage (needle puncture, after using clamp), and change in luminal diameter following pacing stress according to ISO7198 and FDA guidance. As indicated by the results, we experimentally demonstrated that uniquely designed vascular graft Triplex® led to less blood leakage from the vascular graft and less leakage from the needle puncture, although it has fundamental physical properties comparable to those of the vascular grafts using biodegradable material that has been utilized conventionally in clinical settings. Triplex ®is expected to play its role as a clinically beneficial next-generation vascular graft. PMID:23641287

Takamoto, Shinichi

2013-01-01

348

Enhanced permeability and retention (EPR) effect for anticancer nanomedicine drug targeting.  

PubMed

Effective cancer therapy remains one of the most challenging tasks to the scientific community, with little advancement on overall cancer survival landscape during the last two decades. A major limitation inherent to most conventional anticancer chemotherapeutic agents is their lack of tumor selectivity. One way to achieve selective drug targeting to solid tumors is to exploit abnormalities of tumor vasculature, namely hypervascularization, aberrant vascular architecture, extensive production of vascular permeability factors stimulating extravasation within tumor tissues, and lack of lymphatic drainage. Due to their large size, nano-sized macromolecular anticancer drugs administered intravenously (i.v.) escape renal clearance. Being unable to penetrate through tight endothelial junctions of normal blood vessels, their concentration builds up in the plasma rendering them long plasma half-life. More importantly, they can selectively extravasate in tumor tissues due to its abnormal vascular nature. Overtime the tumor concentration will build up reaching several folds higher than that of the plasma due to lack of efficient lymphatic drainage in solid tumor, an ideal application for EPR-based selective anticancer nanotherapy. Indeed, this selective high local concentration of nano-sized anticancer drugs in tumor tissues has proven superior in therapeutic effect with minimal side effects in both preclinical and clinical settings. PMID:20217587

Greish, Khaled

2010-01-01

349

Negative Permeability in Atomic and Molecular Systems at Microwave Frequency  

Microsoft Academic Search

A new mechanism for realizing negative permeability with a three-level ladder-type atomic (or molecular) system at microwave frequency is suggested. The explicit expressions for the magnetic permeability of both steady and transient cases are presented. Compared with the previous schemes to realize negative permeability within the framework of classical electromagnetic theory, the most remarkable feature in the present mechanism is

Xuan Li; Jianqi Shen

2006-01-01

350

Current Sheet Permeability in Electromagnetic Pulsed Plasma Thrusters  

E-print Network

Current Sheet Permeability in Electromagnetic Pulsed Plasma Thrusters J.W. Berkery and E.Y. Choueiri Electric Propulsion and Plasma Dynamics Laboratory (EPPDyL) Mechanical and Aerospace Engineering for the existence of permeability of current sheets in electromagnetic pulsed plasma thrusters. Permeability refers

Choueiri, Edgar

351

Air permeability and trapped-air content in two soils  

Microsoft Academic Search

To improve understanding of hysteretic air permeability relations, a need exists for data on the water content dependence of air permeability, matric pressure, and air trapping (especially for wetting-drying cycles). To obtain these data, a special instrument was designed. The instrument is a combination of a gas permeameter (for air permeability determination), a suction plate apparatus (for retentivity curve determination),

David A. Stonestrom; Jacob Rubin

1989-01-01

352

Geophysical-hydrological identification of field permeabilities through Bayesian updating  

Microsoft Academic Search

A new Bayesian method is developed to identify the spatial distribution of permeabilities. In addition to sparsely sampled permeability and pressure data, this approach incorporates densely sampled seismic velocity data along with semiempirical relationships between seismic and hydraulic soil properties. The procedure consists first of performing a hydrological inversion based solely on the permeability and pressure data. In light of

Nadim Copty; Yoram Rubin; Gary Mavko

1993-01-01

353

Optimum mix design of enhanced permeable concrete – An experimental investigation  

Microsoft Academic Search

Permeable pavement, due to its high porosity and permeability, is considered as an alternative to traditional impervious hard pavements for controlling stormwater in an economical and friendly environmental way. Permeable concrete normally made of single-sized aggregate bound together by Portland cement, using restrictedly as a pavement material, because of its insufficient structural strength. Aimed at developing a new type of

C. Lian; Y. Zhuge

2010-01-01

354

EXPERIMENTAL MEASUREMENTS OF CAPILLARY PRESSURE AND RELATIVE PERMEABILITY HYSTERESIS  

Microsoft Academic Search

Capillary pressure and relative permeability hysteresis have been investigated on core samples with different wetting characteristics. The relative permeability and capillary pressure curves depend on the direction of saturation changes and on the maximum and minimum achieved saturations. A conceptual model to explain the hysteresis trends in both the relative permeability and capillary pressure is presented. The model attributes hysteresis

Shehadeh K. Masalmeh

355

Impact of relative permeability hysteresis on geological CO2 storage  

Microsoft Academic Search

Relative permeabilities are the key descriptors in classical formulations of multiphase flow in porous media. Experimental evidence and an analysis of pore-scale physics demonstrate conclusively that relative permeabilities are not single functions of fluid saturations and that they display strong hysteresis effects. In this paper, we evaluate the relevance of relative permeability hysteresis when modeling geological CO2 sequestration processes. Here

R. Juanes; E. J. Spiteri; F. M. Orr Jr; M. J. Blunt

2006-01-01

356

Dexamethasone reduces gut permeability in pediatric cardiac surgery  

Microsoft Academic Search

Objectives: Little attention has been paid to the effect of the systemic inflammatory response syndrome on intestinal dysfunction in the postoperative period. Several proinflammatory cytokines have been reported to increase the permeability of intestinal mucosa in vitro. We investigated the effect of dexamethasone on gut permeability in pediatric patients undergoing cardiac surgery by using the dual sugar permeability test and

James G. Bovill; Mark G. Hazekamp; Ignacio Malagon; Willem Onkenhout; Margreet Klok; Lisa Linthorst

2010-01-01

357

46 CFR 172.240 - Permeability of spaces.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping...Vessels § 172.240 Permeability of spaces. When doing the calculations required... (a) The permeability of a floodable space, other than a machinery or cargo...

2012-10-01

358

Targeting complement component 5a promotes vascular integrity and limits airway remodeling  

PubMed Central

Increased microvascular dilatation and permeability is observed during allograft rejection. Because vascular integrity is an important indicator of transplant health, we have sought to limit injury to blood vessels by blocking complement activation. Although complement component 3 (C3) inhibition is known to be vasculoprotective in transplantation studies, we recently demonstrated the paradoxical finding that, early in rejection, C3?/? transplant recipients actually exhibit worse microvascular injury than controls. In the genetic absence of C3, thrombin-mediated complement component 5 (C5) convertase activity leads to the generation of C5a (anaphylatoxin), a promoter of vasodilatation and permeability. In the current study, we demonstrated that microvessel thrombin deposition is significantly increased in C3?/? recipients during acute rejection. Thrombin colocalization with microvessels is closely associated with remarkably elevated plasma levels of C5a, vasodilatation, and increased vascular permeability. Administration of NOX-D19, a specific C5a inhibitor, to C3?/? recipients of airway transplants significantly improved tissue oxygenation, limited microvascular leakiness, and prevented airway ischemia, even in the absence of conventional T-cell–directed immunosuppression. As C3 inhibitors enter the clinics, the simultaneous targeting of this thrombin-mediated complement activation pathway and/or C5a itself may confer significant clinical benefit. PMID:23530212

Khan, Mohammad A.; Maasch, Christian; Vater, Axel; Klussmann, Sven; Morser, John; Leung, Lawrence L.; Atkinson, Carl; Tomlinson, Stephen; Heeger, Peter S.; Nicolls, Mark R.

2013-01-01

359

Dealing with vascular conundrums with MR imaging.  

PubMed

Magnetic resonance (MR) imaging is a robust imaging modality for evaluation of vascular diseases. Technological advances have made MR imaging widely available for accurate and time-efficient vascular assessment. In this article the clinical usefulness of MR imaging techniques and their application are reviewed, using examples of vascular abnormalities commonly encountered in clinical practice, including abdominal, pelvic, and thoracic vessels. Common pitfalls and problem solving in interpretation of vascular findings in body MR imaging are also discussed. PMID:24889175

Angthong, Wirana; Semelka, Richard C

2014-07-01

360

Multimodal imaging enables early detection and characterization of changes in tumor permeability of brain metastases.  

PubMed

Our goal was to develop strategies to quantify the accumulation of model therapeutics in small brain metastases using multimodal imaging, in order to enhance the potential for successful treatment. Human melanoma cells were injected into the left cardiac ventricle of immunodeficient mice. Bioluminescent, MR and PET imaging were applied to evaluate the limits of detection and potential for contrast agent extravasation in small brain metastases. A pharmacokinetic model was applied to estimate vascular permeability. Bioluminescent imaging after injecting d-luciferin (molecular weight (MW) 320 D) suggested that tumor cell extravasation had already occurred at week 1, which was confirmed by histology. 7T T1w MRI at week 4 was able to detect non-leaky 100 ?m sized lesions and leaky tumors with diameters down to 200 ?m after contrast injection at week 5. PET imaging showed that (18)F-FLT (MW 244 Da) accumulated in the brain at week 4. Gadolinium-based MRI tracers (MW 559 Da and 2.066 kDa) extravasated after 5 weeks (tumor diameter 600 ?m), and the lower MW agent cleared more rapidly from the tumor (mean apparent permeabilities 2.27 × 10(-5)cm/s versus 1.12 × 10(-5)cm/s). PET imaging further demonstrated tumor permeability to (64)Cu-BSA (MW 65.55 kDa) at week 6 (tumor diameter 700 ?m). In conclusion, high field T1w MRI without contrast may improve the detection limit of small brain metastases, allowing for earlier diagnosis of patients, although the smallest lesions detected with T1w MRI were permeable only to d-luciferin and the amphipathic small molecule (18)F-FLT. Different-sized MR and PET contrast agents demonstrated the gradual increase in leakiness of the blood tumor barrier during metastatic progression, which could guide clinicians in choosing tailored treatment strategies. PMID:24161382

Thorsen, Frits; Fite, Brett; Mahakian, Lisa M; Seo, Jai W; Qin, Shengping; Harrison, Victoria; Johnson, Sarah; Ingham, Elizabeth; Caskey, Charles; Sundstrøm, Terje; Meade, Thomas J; Harter, Patrick N; Skaftnesmo, Kai Ove; Ferrara, Katherine W

2013-12-28

361

Redox Processes Underlying the Vascular Repair Reaction  

Microsoft Academic Search

Accumulating evidence indicates that vascular dysfunction in atherosclerosis, hypertension, and diabetes is either caused by or accompanied by oxidative stress in the vessel wall. In particular, the role of redox processes as mediators of vascular repair and contributors to post-angioplasty restenosis is increasingly evident. Yet the pathophysiology of such complex phenomena is still unclear. After vascular injury, activation of enzymes

Paulo F. Leite; Marcel Liberman; Fábio Sandoli de Brito; Francisco R. M. Laurindo

2004-01-01

362

Hookworm (Necator americanus) larval enzymes disrupt human vascular endothelium.  

PubMed

Knowledge of the molecular mechanisms used by Necator americanus larvae to penetrate the human skin and the vasculature would aid the development of effective vaccines against this important pathogen. In this work, the impact of N. americanus exsheathing fluid (EF) and excretory/secretory products (ES) on the endothelial barrier was examined using human umbilical vein endothelial cells (HUVEC). Cellular responses were assessed by investigating molecular changes at cell-cell junctions and by determining levels of secreted IL-6, IL-8, and vascular endothelial growth factor (VEGF) in the culture medium. It would appear that a repertoire of larval proteases caused a dose-related increase in endothelial permeability as characterized by a decrease in monolayer resistance with increased permeation of tracer-albumin. These barrier changes were associated with disruption of junctional vascular endothelial cadherin (VE-cadherin) and F-actin and an increase in endothelial secretion of IL-6 and IL-8. Our data suggest that larval proteases play an important role in negotiating the endothelium. PMID:20810819

Souadkia, Nahed; Brown, Alan; Leach, Lopa; Pritchard, David I

2010-09-01

363

Permeability of caulking compounds to 222Rn.  

PubMed

Caulking compounds have been tested as 222Rn barriers. Of these, the most effective is GE acrylic Latex Silicone Caulk, 0.2 cm of which attenuates 222Rn by 98% to 99.9%. The same thickness of two commercial 222Rn barriers attenuates radon by 75% to 90%. Permeabilities range from 0.3 to 140 x 10(-8) cm2 s-1. PMID:1727418

Fleischer, R L

1992-01-01

364

Inorganic nitrogen transformations within permeable carbonate sands  

NASA Astrophysics Data System (ADS)

A combination of in-situ push pull tests and a flow through reactor trial were used to quantify the inorganic nitrogen sinks in the permeable carbonate sands of a tropical coral cay (Heron Island - Great Barrier Reef). Addition of dissolved inorganic nitrogen (DIN in the form of nitrate - NO3-, and ammonium - NH4+) directly into sediment porewater resulted in uptake of up to 97% and 60% of added DIN respectively. The initial push pull experiment qualitatively showed that dissimilatory nitrate reduction to ammonia (DNRA), denitrification and nitrification were all active in the sediments. A flow through reactor experiment provided a more detailed approach to quantify these processes and showed that both denitrification and DNRA occurred within the sands at rates of 7.3 and 5.5 ?mol N cm-3 d-1, respectively. Unexpectedly the addition of labile organic material (fresh coral spawn) to the permeable sands did not result in the release of DIN from the reactors, on the contrary it resulted in the increased uptake of both NO3- and NH4+. This was most likely because of the stimulated N uptake associated with the addition of high C:N coral spawn material. The bulk of NH4+ produced via DNRA was found to be adsorbed to sediments within the reactor and was not released with the outlet water. A mass balance over the entire experimental period showed that more inorganic N was retained within the sediments than lost as gaseous products. Our results point to permeable carbonate sands acting as reservoirs of N under the influence of advective flow, even during sudden enrichment periods such as those following coral mass spawning. This implies that permeable carbonate sands may help to buffer coral reefs during periods of extreme oligotrophy.

Erler, Dirk V.; Santos, Isaac R.; Eyre, Bradley D.

2014-04-01

365

Study of the therapeutic benefit of cationic copolymer administration to vascular endothelium under mechanical stress.  

PubMed

Pulmonary edema and the associated increases in vascular permeability continue to represent a significant clinical problem in the intensive care setting, with no current treatment modality other than supportive care and mechanical ventilation. Therapeutic compound(s) capable of attenuating changes in vascular barrier function would represent a significant advance in critical care medicine. We have previously reported the development of HPMA-based copolymers, targeted to endothelial glycocalyx that are able to enhance barrier function. In this work, we report the refinement of copolymer design and extend our physiological studies to demonstrate that the polymers: 1) reduce both shear stress and pressure-mediated increase in hydraulic conductivity, 2) reduce nitric oxide production in response to elevated hydrostatic pressure and, 3) reduce the capillary filtration coefficient (K(fc)) in an isolated perfused mouse lung model. These copolymers represent an important tool for use in mechanotransduction research and a novel strategy for developing clinically useful copolymers for the treatment of vascular permeability. PMID:20932573

Giantsos-Adams, Kristina; Lopez-Quintero, Veronica; Kopeckova, Pavla; Kopecek, Jindrich; Tarbell, John M; Dull, Randal

2011-01-01

366

Angiotensin converting enzyme inhibition reduces retinal overexpression of vascular endothelial growth factor and hyperpermeability in experimental diabetes  

Microsoft Academic Search

Aims\\/hypothesis. Angiotensin converting enzyme (ACE) inhibition has been recently suggested to have retinoprotective actions in diabetic patients\\u000a but the mechanism of this effect is not known. In vitro, angiotensin II stimulates expression of vascular endothelial growth\\u000a factor (VEGF), a permeability-inducing and endothelial cell specific angiogenic factor which has been implicated in the pathogenesis\\u000a of diabetic retinopathy in humans and in

R. E. Gilbert; D. J. Kelly; A. J. Cox; J. L. Wilkinson-Berka; J. R. Rumble; T. Osicka; S. Panagiotopoulos; V. Lee; E. C. Hendrich; G. Jerums; M. E. Cooper

2000-01-01

367

Porosity and Permeability of Chondritic Materials  

NASA Technical Reports Server (NTRS)

We have investigated the porosity of a large number of chondritic interplanetary dust particles and meteorites by three techniques: standard liquid/gas flow techniques, a new, non-invasive ultrasonic technique, and image processing of backscattered images . The latter technique is obviously best suited to sub-kg sized samples. We have also measured the gas and liquid permeabilities of some chondrites by two techniques: standard liquid/gas flow techniques, and a new, non-destructive pressure release technique. We find that chondritic IDP's have a somewhat bimodal porosity distribution. Peaks are present at 0 and 4% porosity; a tail then extends to 53%. These values suggest IDP bulk densities of 1.1 to 3.3 g/cc. Type 1-3 chondrite matrix porosities range up to 30%, with a peak at 2%. The bulk porosities for type 1-3 chondrites have the same approximate range as exhibited by matrix, indicating that other components of the bulk meteorites (including chondrules and aggregates) have the same average porosity as matrix. These results reveal that the porosity of primitive materials at scales ranging from nanogram to kilogram are similar, implying similar accretion dynamics operated through 12 orders of size magnitude. Permeabilities of the investigated chondrites vary by several orders of magnitude, and there appears to be no simple dependence of permeability with degree of aqueous alteration, or chondrite type.

Zolensky, Michael E.; Corrigan, Catherine M.; Dahl, Jason; Long, Michael

1996-01-01

368

On Russell index reconstitution  

Microsoft Academic Search

This paper investigates whether abnormal returns permanently exist in transparent U.S. Russell index reconstitution and provides\\u000a evidence to disentangle the competing hypotheses associated with the index effect in the literature. Additions to Russell\\u000a 1000 generate cumulative excess returns of 10.9% from 2 days before May 31 to June 30 while stocks deleted from Russell 2000\\u000a Growth Index suffer cumulative loss

Hsiu-Lang Chen

2006-01-01

369

A catalog of porosity and permeability from core plugs in siliciclastic rocks  

USGS Publications Warehouse

Porosity and permeability measurements on cored samples from siliciclastic formations are presented for 70 data sets, taken from published data and descriptions. Data sets generally represent specific formations, usually from a limited number of wells. Each data set is represented by a written summary, a plot of permeability versus porosity, and a digital file of the data. The summaries include a publication reference, the geologic age of the formation, location, well names, depth range, various geologic descriptions, and core measurement conditions. Attributes such as grain size or depositional environment are identified by symbols on the plots. An index lists the authors and date, geologic age, formation name, sandstone classification, location, basin or structural province, and field name.

Nelson, Philip H.; Kibler, Joyce E.

2003-01-01

370

Atrial Natriuretic Peptide Reduces Vascular Leakage and Choroidal Neovascularization  

PubMed Central

Atrial natriuretic peptide (ANP) is a hormone with diuretic, natriuretic, and vasodilatory properties. ANP blocks vascular endothelial growth factor (VEGF) production and signaling in vitro; however, its role in vascular leakage and angiogenesis is unknown. In vitro, retinal barrier permeability (transepithelial electrical resistance (TEER)) was measured in cultured retinal endothelial (HuREC) and retinal epithelial (ARPE-19) cells with VEGF (10 ng/ml), ANP (1 pM to 1 ?mol/L), and/or isatin, an ANP receptor antagonist. In vivo, blood-retinal barrier (BRB) leakage was studied using the Evans Blue dye technique in rats treated with intravitreal injections of ANP, VEGF, or vehicle. Choroidal neovascularization was generated by laser injury, and 7 days later, lesion size and leakage was quantitated. ANP significantly reversed VEGF-induced BRB TEER reduction in both HuREC and ARPE-19 cells, modeling the inner and the outer BRB, respectively. Isatin, a specific ANP receptor antagonist, reversed ANP’s effect. ANP reduced the response of ARPE-19 cells to VEGF apically but not basolaterally, suggesting polarized expression of the ANP receptors in these cells. ANP’s TEER response was concentration but not time dependent. In vivo, ANP significantly reduced VEGF-induced BRB leakage and the size of laser-induced choroidal neovascularization lesions. In sum, ANP is an effective inhibitor of VEGF-induced vascular leakage and angiogenesis in vivo. These results may lead to new treatments for ocular diseases where VEGF plays a central role, such as age-related macular degeneration or diabetic retinopathy. PMID:19910509

Lara-Castillo, Nuria; Zandi, Souska; Nakao, Shintaro; Ito, Yasuhiro; Noda, Kousuke; She, Haicheng; Ahmed, Muna; Frimmel, Sonja; Ablonczy, Zsolt; Hafezi-Moghadam, Ali

2009-01-01

371

Morphological and functional vascular changes induced by childhood obesity  

Microsoft Academic Search

Background: To investigate endothelial dysfunction and morphological vascular changes in childhood obesity.Methods: 93 overweight\\/obese children (body mass index 26 ± 5 kg\\/m2; median 26 kg\\/m2; interquartile range 22–28 kg\\/m2), mean age 10.9 ± 2.7 years, underwent a check-up of total, high-density lipoprotein- and low-density lipoprotein-cholesterol, triglycerides, C-reactive protein, erythrocyte sedimentation rate, and white blood cell count, together with ultrasound measures

Marco Matteo Ciccone; Vito Miniello; Roberto Marchioli; Pietro Scicchitano; Francesca Cortese; Vincenzo Palumbo; Stefano Giuseppe Primitivo; Marco Sassara; Gabriella Ricci; Santa Carbonara; Michele Gesualdo; Lucia Diaferio; Giuseppe Mercuro; Giovanni De Pergola; Paola Giordano; Stefano Favale

2011-01-01

372

Changes in rock salt permeability due to nearby excavation  

SciTech Connect

Changes in brine and gas permeability of rock salt as a result of nearby excavation (mine-by) have been measured from the underground workings of the WIPP facility. Prior to the mine-by, the formation responds as a porous medium with a very low brine permeability, a significant pore (brine) pressure and no measurable gas permeability. The mine-by excavation creates a dilated, partially saturated zone in the immediate vicinity of the excavation with an increased permeability to brine and a measurable permeability to gas. The changes in hydrologic properties are discussed in the context of pore structure changes.

Stormont, J C [Sandia National Labs., Albuquerque, NM (United States); Howard, C L [RE/SPEC, Inc., Carlsbad, NM (United States); Daemen, J J.K. [Nevada Univ., Reno, NV (United States)

1991-07-01

373

Human Development Index Data  

NSDL National Science Digital Library

This data set traces the varying patterns of national progress in recent decades, documenting impressive long-term Human Development Index (HDI) gains even in most low-income countries. The data set also includes three innovative new measurements: the Inequality-adjusted Human Development Index (IHDI), the Gender Inequality Index (GII) and the Multidimensional Poverty Index (MPI). The data set is available in both CSV and SDMX file formats and contains more than 100 indicators that measure quality of life for all UN member states.

Nations, United

374

Vascular Pathophysiology in Hearing Disorders  

PubMed Central

The inner ear vasculature is responsible for maintenance of the blood-labyrinth barrier, transport of systemic hormones for ion homeostasis, and supplying nutrients for metabolic functions. Unfortunately, these blood vessels also expose the ear to circulating inflammatory factors resulting from systemic diseases. Thus, while the inner ear blood vessels are critical for normal function, they also are facilitating pathologic mechanisms that result in hearing and vestibular dysfunction. In spite of these numerous critical roles of inner ear vasculature, little is known of its normal homeostatic functions and how these are compromised in disease. The objective of this review is to discuss the current concepts of vascular biology, how blood vessels naturally respond to circulating inflammatory factors, and how such mechanisms of vascular pathophysiology may cause hearing loss. PMID:25346568

Trune, Dennis R.; Nguyen-Huynh, Anh

2014-01-01

375

Evaluating Permeability Enchancement Using Electrical Techniques  

SciTech Connect

Enhanced Geothermal Systems (EGS) development projects involve the artificial stimulation of relatively impermeable high-temperature underground regions (at depths of 2-4 kilometers or more) to create sufficient permeability to permit underground fluid circulation, so that hot water can be withdrawn from production wells and used to generate electric power. Several major research projects of this general type have been undertaken in the past in New Mexico (Fenton Hill), Europe, Japan and Australia. Recent U.S. activities along these lines focus mainly on stimulating peripheral areas of existing operating hydrothermal fields rather than on fresh 'greenfield' sites, but the long-term objective of the Department of Energy's EGS program is the development of large-scale power projects based on EGS technology (MIT, 2006; NREL, 2008). Usually, stimulation is accomplished by injecting water into a well at high pressure, enhancing permeability by the creation and propagation of fractures in the surrounding rock (a process known as 'hydrofracturing'). Beyond just a motivation, low initial system permeability is also an essential prerequisite to hydrofracturing. If the formation permeability is too high, excessive fluid losses will preclude the buildup of sufficient pressure to fracture rock. In practical situations, the actual result of injection is frequently to re-open pre-existing hydrothermally-mineralized fractures, rather than to create completely new fractures by rupturing intact rock. Pre-existing fractures can often be opened using injection pressures in the range 5-20 MPa. Creation of completely new fractures will usually require pressures that are several times higher. It is preferable to undertake development projects of this type in regions where tectonic conditions are conducive to shear failure, so that when pre-existing fractures are pressurized they will fail by shearing laterally. If this happens, the fracture will often stay open afterwards even if injection subsequently ceases. The principal barrier to EGS utilization for electricity generation is project economics. Costs for geothermal electricity obtained from conventional hydrothermal systems are just marginally competitive. Unless and until the costs of routinely and reliably creating and exploiting artificial subterranean fracture networks that can deliver useful quantities of hot fluid to production wells for long periods of time (years) are reduced to levels comparable to those of a conventional geothermal development project, EGS will be of little interest to the electrical power industry. A significant obstacle to progress in projects of this general type is the difficulty of appraising the properties (geometry, fluid transmissivity, etc.) of the fracture(s) created/re-opened by injection. Sustainability of power production is critically dependent upon reservoir thermal sweep efficiency, which depends in turn on the geometry of the fracture network and its interconnections with the various production and injection wells used to circulate fluid underground. If no permeable connections are created between the wells, fluid flow will be too slow for practical utility. If the connections are too good, however (such as a production/injection well pair connected by a single very permeable fracture), production wellhead temperatures will decline rapidly. Unless the permeable fractures created by hydrofracturing can be accurately mapped, the cost of subsequent trial-and-error drilling to try to establish a suitable fluid circulation system is likely to dominate project economics and render EGS impractical.

John W. Pritchett

2008-09-01

376

Membrane stress increases cation permeability in red cells.  

PubMed

The human red cell is known to increase its cation permeability when deformed by mechanical forces. Light-scattering measurements were used to quantitate the cell deformation, as ellipticity under shear. Permeability to sodium and potassium was not proportional to the cell deformation. An ellipticity of 0.75 was required to increase the permeability of the membrane to cations, and flux thereafter increased rapidly as the limits of cell extension were reached. Induction of membrane curvature by chemical agents also did not increase cation permeability. These results indicate that membrane deformation per se does not increase permeability, and that membrane tension is the effector for increased cation permeability. This may be relevant to some cation permeabilities observed by patch clamping. PMID:7858123

Johnson, R M

1994-11-01

377

The costs of vascular dementia  

Microsoft Academic Search

Objectives: To estimate the costs of Medicare patients with vascular dementia (VaD). To compare the costs of VaD to Alzheimer's disease (AD) and controls without dementia. Methods: The study samples were drawn from community-dwelling patients in a large Medicare managed care organization (MCO) operating in the Northeast region of the USA. Costs for three study groups were contrasted in the

Howard Fillit; Jerrold Hill

2002-01-01

378

Vascular Access Monitoring Improves Outcomes  

Microsoft Academic Search

Vascular access monitoring can identify patients at increased risk of future access thrombosis. When coupled with a program of elective stenosis correction, access thrombosis rates decline approximately 50–75%. This results in arteriovenous (AV) fistula thrombosis rates of 0.1–0.2\\/patient year (vs. 0.2–0.4 at baseline) and AV graft thrombosis rates <0.5\\/patient year (vs. 0.8–1.2 thromboses\\/patient year at baseline). Evaluating the long-term impact

Jeffrey J. Sands

2005-01-01

379

Circulating Vascular Endothelial Growth Factor  

Microsoft Academic Search

Despite significant advances in early detection and treatment, breast cancer still remains the major cause of cancer-related\\u000a death in women. Many studies suggest a relationship between angiogenesis and breast cancer prognosis. Angiogenesis is the\\u000a complex process leading to the formation of new blood vessels from pre-existing vascular network. The VEGF is the most active\\u000a growth factor involved in angiogenesis; more

Roberta Sarmiento; Roberta Franceschini; Sabrina Meo; Massimo Gion; Raffaele Longo; Giampietro Gasparini

380

Vascular Abnormalities in Diabetes Mellitus  

Microsoft Academic Search

\\u000a Diabetes mellitus causes a variety of changes in the vascular system, affecting both the micro-and macrovasculature. Classical\\u000a pathologies in the microvasculature are manifested as diabetic retinopathy and nephropathy. Macrovascular diseases are observed\\u000a in the coronary arteries, large peripheral vasculature involving mostly the lower limbs, and cerebral vessels. In addition,\\u000a diabetes and insulin resistance are strongly associated with essential hypertension, and

Katherine D. Hein; George L. King

381

Biologic Nanoparticles and Vascular Disease  

Microsoft Academic Search

\\u000a Sustained or repeating chronic infections have been linked to arterial calcification. Biologic nanoparticles (NPs) that propagate\\u000a in culture have been isolated from calcified soft tissues. When inoculated into experimental animals, NPs appear to exacerbate\\u000a the arterial response to injury, up to and including medial discontinuity and vascular occlusion. These NPs may be re-assembled\\u000a proteins and microvesicles derived from mammalian cells

Maria K. Schwartz; John C. Lieske; Virginia M. Miller

382

Lymphatic complications after vascular interventions  

PubMed Central

Introduction Lymphorrhea due to classical and mini-invasive surgical interventions on femoral and popliteal arteries is a serious hindrance to patient treatment. Depending on the experience of a particular center, the incidence and frequency of this type of complication may constitute a serious clinical problem. While the level of lymphorrhea intensity and its duration result in certain foreseeable consequences, their treatment can be a time-consuming and multistep procedure. Aim To compare different types of vascular interventions with lymphorrhea occurrence. Material and methods The authors conducted a retrospective analysis of lymphatic complications based on the material collected between 2005 and 2012 at the Department of Vascular and Endovascular Surgery of the Military Institute of Medicine in Warsaw and in the Department of Interventional Cardiology and Angiology of the Institute of Cardiology in Anin, Warsaw, in 2009–2012. Results Maintaining due thoroughness when dissecting tissues and treating the cutting line in this area with ligatures and tissue puncture are the most reliable methods of minimizing the risk of lymphatic leakage after surgical procedures performed in a classical way. The lymphatic complication under analysis is far less likely to occur when procedures are performed as planned and an endovascular technique is used – statistical significance p < 0.05. Minimally invasive and fully percutaneous procedures performed via needle puncture, including the use of the fascial closure technique to close the femoral artery, eliminate the likelihood of the occurrence of this vascular complication – statistical significance was found with p value less than 0.05. Conclusions We concluded that in every case by minimizing the vascular approach we protected the patient against lymphatic complications. PMID:25337168

Obara, Andrzej; Maruszynski, Marek; Witkowski, Adam; Dabrowski, Maciej; Chmielak, Zbigniew

2014-01-01

383

Mechanoresponsive networks controlling vascular inflammation.  

PubMed

Atherosclerosis is a chronic inflammatory disease of arteries that develops preferentially at branches and bends that are exposed to disturbed blood flow. Vascular function is modified by flow, in part, via the generation of mechanical forces that alter multiple physiological processes in endothelial cells. Shear stress has profound effects on vascular inflammation; high uniform shear stress prevents leukocyte recruitment to the vascular wall by reducing endothelial expression of adhesion molecules and other inflammatory proteins, whereas low oscillatory shear stress has the opposite effects. Here, we review the molecular mechanisms that underpin the effects of shear stress on endothelial inflammatory responses. They include shear stress regulation of inflammatory mitogen-activated protein kinase and nuclear factor-?B signaling. High shear suppresses these pathways through the induction of several negative regulators of inflammation, whereas low shear promotes inflammatory signaling. Furthermore, we summarize recent studies indicating that inflammatory signaling is highly sensitive to pulse wave frequencies, magnitude, and direction of flow. Finally, the importance of systems biology approaches (including omics studies and functional screening) to identify novel mechanosensitive pathways is discussed. PMID:24947523

Bryan, Matthew T; Duckles, Hayley; Feng, Shuang; Hsiao, Sarah T; Kim, Hyejeong R; Serbanovic-Canic, Jovana; Evans, Paul C

2014-10-01

384

[Vascular Ehlers-Danlos syndrome].  

PubMed

Vascular type Ehlers-Danlos syndrome (EDS) is a rare inherited disease with an autosomal dominant trait. The mutation of the COL3A1 gene which encodes type III collagen, is responsible of early vascular (spontaneous arterial rupture or dissection), digestive (perforation) and obstetrical events (uterine and arterial rupture). Diagnosis of the disease is primarily clinical, especially in case of characteristic morphologic features. Diagnostic certainty is obtained by evidencing the mutation of the COL3A1 gene. Some arterial lesions are suggestive of the disease, as dissecting aneurysms of the internal carotid, of the iliac arteries, and of the anterior visceral aortic branches, fusiform aneurisms of the splenic artery, and the occurrence of a non traumatic direct carotid-cavernous fistula. The occurrence of a spontaneous peritonitis or of an extensive perineal tear after delivery should also draw physician's attention. Because of the unpredictability of arterial or organ rupture, any patient diagnosed with vascular type EDS presenting with an acute pain syndrome should be considered as a trauma situation and be investigated straightaway by CT-scan or MRI testing, in order to eliminate a life threatening complication. PMID:19462862

Frank, Michael

2009-04-20

385

Acute management of vascular air embolism  

PubMed Central

Vascular air embolism (VAE) is known since early nineteenth century. It is the entrainment of air or gas from operative field or other communications into the venous or arterial vasculature. Exact incidence of VAE is difficult to estimate. High risk surgeries for VAE are sitting position and posterior fossa neurosurgeries, cesarean section, laparoscopic, orthopedic, surgeries invasive procedures, pulmonary overpressure syndrome, and decompression syndrome. Risk factors for VAE are operative site 5 cm above the heart, creation of pressure gradient which will facilitate entry of air into the circulation, orogenital sex during pregnancy, rapid ascent in scuba (self contained underwater breathing apparatus) divers and barotrauma or chest trauma. Large bolus of air can lead to right ventricular air lock and immediate fatality. In up to 35% patient, the foramen ovale is patent which can cause paradoxical arterial air embolism. VAE affects cardiovascular, pulmonary and central nervous system. High index of clinical suspicion is must to diagnose VAE. The transesophgeal echocardiography is the most sensitive device which will detect smallest amount of air in the circulation. Treatment of VAE is to prevent further entrainment of air, reduce the volume of air entrained and haemodynamic support. Mortality of VAE ranges from 48 to 80%. VAE can be prevented significantly by proper positioning during surgery, optimal hydration, avoiding use of nitrous oxide, meticulous care during insertion, removal of central venous catheter, proper guidance, and training of scuba divers. PMID:20009308

Shaikh, Nissar; Ummunisa, Firdous

2009-01-01

386

Permeability-porosity relationships of subduction zone sediments  

USGS Publications Warehouse

Permeability-porosity relationships for sediments from the northern Barbados, Costa Rica, Nankai, and Peru subduction zones were examined based on sediment type, grain size distribution, and general mechanical and chemical compaction history. Greater correlation was observed between permeability and porosity in siliciclastic sediments, diatom oozes, and nannofossil chalks than in nannofossil oozes. For siliciclastic sediments, grouping of sediments by percentage of clay-sized material yields relationships that are generally consistent with results from other marine settings and suggests decreasing permeability as percentage of clay-sized material increases. Correction of measured porosities for smectite content improved the correlation of permeability-porosity relationships for siliciclastic sediments and diatom oozes. The relationship between permeability and porosity for diatom oozes is very similar to the relationship in siliciclastic sediments, and permeabilities of both sediment types are related to the amount of clay-size particles. In contrast, nannofossil oozes have higher permeability values by 1.5 orders of magnitude than siliciclastic sediments of the same porosity and show poor correlation between permeability and porosity. More indurated calcareous sediments, nannofossil chalks, overlap siliciclastic permeabilities at the lower end of their measured permeability range, suggesting similar consolidation patterns at depth. Thus, the lack of correlation between permeability and porosity for nannofossil oozes is likely related to variations in mechanical and chemical compaction at shallow depths. This study provides the foundation for a much-needed global database with fundamental properties that relate to permeability in marine settings. Further progress in delineating controls on permeability requires additional carefully documented permeability measurements on well-characterized samples. ?? 2010 Elsevier B.V.

Gamage, K.; Screaton, E.; Bekins, B.; Aiello, I.

2011-01-01

387

Children's Stress Index.  

ERIC Educational Resources Information Center

This double issue of the "ZPG Reporter" focuses on the theme of ZPG's Children's Stress Index", the first national survey of children's well-being based on population- related pressures. Using an extensive list of social, economic, and environmental factors that affect the lives of children, the index ranks 828 cities, counties, and metropolitan…

Sherman, Dianne, Ed.

1993-01-01

388

Universal Index System  

NASA Technical Reports Server (NTRS)

The Universal Index System (UIS) is an index management system that uses a uniform interface to solve the heterogeneity problem among database management systems. UIS provides an easy-to-use common interface to access all underlying data, but also allows different underlying database management systems, storage representations, and access methods.

Kelley, Steve; Roussopoulos, Nick; Sellis, Timos; Wallace, Sarah

1993-01-01

389

Machine-Aided Indexing.  

ERIC Educational Resources Information Center

Progress is reported on the development of a partial syntactic analysis technique for indexing text. Although over 500,000 words of text have been indexed, this report is limited to the analysis of results at the 115,000 word level. There is the expectation that the error rate of commission, the selection of grammatically incorrect word sequences,…

Klingbiel, Paul H.

390

Probabilistic latent semantic indexing  

Microsoft Academic Search

Probabilistic Latent Semantic Indexing is a novel approach to automated document indexing which is based on a statistical latent class model for factor analysis of count data. Fitted from a training corpus of text documents by a generalization of the Expectation Maximization algorithm, the utilized model is able to deal with domain-specific synonymy as well as with polysemous words. In

Thomas Hofmann

1999-01-01

391

A Computer Calculated Index.  

ERIC Educational Resources Information Center

The Gunning Fog Index of readability indicates both the average length of words and the difficult words (three or more syllables) in written material. This document describes a business communication course at Wayne State University in which students calculate the Gunning Fog Index of two of their writing assignments with the aid of the…

Brown, Francis J.

392

Huperzine A for vascular dementia  

PubMed Central

Background Huperzine A, a form of herbal medicine, has been considered as an alternative treatment for vascular dementia (VaD) in China. Objectives To assess the efficacy and safety of Huperzine A in patients with vascular dementia. Search methods We searched ALOIS: the Cochrane Dementia and Cognitive Improvement Group’s Specialized Register on 10 February 2011 using the terms: chinese, plants, huperzine, HUP, ayapin, scoparon. ALOIS contains records of clinical trials identified from monthly searches of a number of major healthcare databases (The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS), numerous trial registries and grey literature sources. We also searched the following databases in March 2011 using the terms ‘Huperzine A’, ‘Shishanjianjia’, ‘Haboyin’ and ‘Shuangyiping’: The Chinese Biomedical Database (CBM) (1977 to March 2011); Chinese Science and Technique Journals Database (VIP) (1989 to March 2011); China National Knowledge Infrastructure (CNKI) (1979 to March 2011); Google (March 2011). In addition, we searched relevant reference lists. We also contacted researchers to request additional information where necessary. Selection criteria We considered randomized controlled trials comparing Huperzine A with placebo in people with vascular dementia eligible for inclusion. Data collection and analysis Two review authors independently applied the inclusion criteria, assessed trial quality and extracted the data. We resolved any disagreement by discussion. Main results We included only one small trial, involving 14 participants with vascular dementia. No significant effect of Huperzine A on cognitive function measured by MMSE (WMD 2.40; 95% CI ?4.78 to 9.58) was observed. There was a significant beneficial effect of Huperzine A on performance of activities of daily living (WMD ?13.00; 95% CI ?23.24 to ?2.76) after six months of treatment. No deaths from any cause at the end of treatment were reported. Behaviour, quality of life and caregiver burden were not assessed in the included trial. Authors’ conclusions There is currently no high quality evidence to support the use of Huperzine A for the treatment of vascular dementia. Further randomized placebo controlled trials are needed to determine whether there is worthwhile benefit. PMID:19370686

Hao, Zilong; Liu, Ming; Liu, Zhiqin; Lu, DongHao

2014-01-01

393

Active metamaterials: sign of refraction index and gain-assisted dispersion management  

E-print Network

We derive an approach to define the causal direction of the wavevector of modes in optical metamaterials, which in turn, determines signs of refractive index and impedance as a function of {\\it real and imaginary} parts of dielectric permittivity and magnetic permeability. We use the developed technique to demonstrate that the interplay between resonant response of constituents of metamaterials can be used to achieve efficient dispersion management. Finally we demonstrate broadband dispersion-less index and impedance matching in active nanowire-based negative index materials. Our work opens new practical applications of negative index composites for broadband lensing, imaging, and pulse-routing.

Alexander A. Govyadinov; Mikhail A. Noginov; Viktor A. Podolskiy

2007-04-27

394

Persistently Elevated Right Ventricular Index of Myocardial Performance in Preterm Infants with Incipient Bronchopulmonary Dysplasia  

Microsoft Academic Search

ObjectivesElevated pulmonary vascular resistance occurs during the first days after birth in all newborn infants and persists in infants at risk for bronchopulmonary dysplasia (BPD).It is difficult to measure in a non-invasive fashion. We assessed the usefulness of the right ventricular index of myocardial performance (RIMP) to estimate pulmonary vascular resistance in very low birth weight infants.Study DesignProspective echocardiography on

Christoph Czernik; Stefanie Rhode; Boris Metze; Gerd Schmalisch; Christoph Bührer

2012-01-01

395

The kinetics of denitrification in permeable sediments  

NASA Astrophysics Data System (ADS)

Permeable sediments comprise the majority of shelf sediments, yet the rates of denitrification remain highly uncertain in these environments. Computational models are increasingly being used to understand the dynamics of denitrification in permeable sediments, which are complex environments to study experimentally. The realistic implementation of such models requires reliable experimentally derived data on the kinetics of denitrification. Here we undertook measurements of denitrification kinetics as a function of nitrate concentration and in the presence and absence of oxygen, in carefully controlled flow through reactor experiments on sediments taken from six shallow coastal sites in Port Phillip Bay, Victoria, Australia. The results showed that denitrification commenced rapidly (within 30 min) after the onset of anoxia and the kinetics could be well described by Michaelis-Menten kinetics with half saturation constants (apparent Km) ranging between 1.5 and 19.8 ?M, and maximum denitrification rate (Vmax) were in the range of 0.9-7.5 nmol mL-1 h-1. The production of N2 through anaerobic ammonium oxidation (anammox) was generally found to be less than 10% that of denitrification. Vmax were in the same range as previously reported in cohesive sediments despite organic carbon contents one order of magnitude lower for the sediments studied here. The ratio of sediment O2 consumption to Vmax was in the range of 0.02-0.09, and was on average much lower than the theoretical ratio of 0.8. The most likely explanation for this is that the microbial community is not able to instantaneously shift or optimally use a particular electron acceptor in the highly dynamic redox environment experienced in permeable sediments. Consistent with this explanation, subsequent longer-term experiments over 5 days showed that denitrification rates increased by a factor of 10 within 3 days of the permanent onset of anoxia. In contrast to previous studies, we did not observe any significant rates of oxic denitrification.

Evrard, Victor; Glud, Ronnie N.; Cook, Perran L. M.

2013-04-01

396

Gas permeability measurements for film envelope materials  

DOEpatents

Method and apparatus for measuring the permeability of polymer film materials such as used in super-insulation powder-filled evacuated panels (PEPs) reduce the time required for testing from several years to weeks or months. The method involves substitution of a solid non-outgassing body having a free volume of between 0% and 25% of its total volume for the usual powder in the PEP to control the free volume of the ``body-filled panel.`` Pressure versus time data for the test piece permit extrapolation to obtain long term performance of the candidate materials. 4 figs.

Ludtka, G.M.; Kollie, T.G.; Watkin, D.C.; Walton, D.G.

1998-05-12

397

Gas permeability measurements for film envelope materials  

DOEpatents

Method and apparatus for measuring the permeability of polymer film materials such as used in super-insulation powder-filled evacuated panels (PEPs) reduce the time required for testing from several years to weeks or months. The method involves substitution of a solid non-outgassing body having a free volume of between 0% and 25% of its total volume for the usual powder in the PEP to control the free volume of the "body-filled panel". Pressure versus time data for the test piece permit extrapolation to obtain long term performance of the candidate materials.

Ludtka, Gerard M. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Watkin, David C. (Clinton, TN); Walton, David G. (Knoxville, TN)

1998-01-01

398

Dual-band tunable negative refractive index metamaterial with F-Shape structure  

NASA Astrophysics Data System (ADS)

This paper presents a negative refractive index tunable metamaterial based on F-Shape structure which is capable of achieving dual-band negative permeability and permittivity, thus dual-band negative refractive index. An electromagnetic simulation was performed and effective media parameters were retrieved. Numerical investigations show clear existence of two frequency bands in which permeability and permittivity both are negative. The two negative refractive index bandwidths are from 23.8 GHz to 24.1 GHz and from 28.3 GHz to 34.9 GHz, respectively. The geometry of the structure is simple so it can easily be fabricated. The proposed structure can be used in multiband and broad band devices, as the band range in second negative refractive index region is 7 GHz, for potential applications instead of using complex geometric structures and easily tuned by varying the separation between the horizontal wires.

Rizwan, Muhammad; Jin, Hai-Bo; Rehman, Fida; Hou, Zhi-Ling; Li, Jing-Bo; Butt, Faheem K.; Ali, Zulfiqar

2014-08-01

399

Potential vorticity index  

NASA Technical Reports Server (NTRS)

Using standard data analysis techniques, researchers explore the links between disturbance growth and quasi-geostrophic potential vorticity (PV) gradients; appearance and disappearance of cutoff lows and blocking highs and their relation to a zonal index (properly defined in terms of PV); and teleconnections between different flow patterns and their relation to the zonal index. It was found that the PV index and the eddy index correlate better than a zonal index (defined by zonal wind) and the eddy index. In the frequency domain there are three frequencies (.03, .07 and .17 cpd (cycle per day) corresponding to periods of 33, 14 and 6 days) at which PV index and the eddy index exhibit local maxima. The high correlation found at periods of 33 days is mainly due to eddy activity at high latitudes while the local correlation maxima found at the shorter periods are mainly due mid-latitude eddy activity. The correlation between the PV index and the geopotential height anomaly at 500 mb, at each grid point in the Northern Hemisphere, shows the existence of most of the teleconnection patterns summarized by Wallace and Gutzler (1981): the North Atlantic Oscillation, the North Pacific Oscillation, and the Pacific/North American patterns. Results show that the Isentropic Potential Vorticity (IPV) analysis can be a very useful and powerful tool when used to understand the dynamics of several large scale atmospheric systems. Although the data are limited to only one winter, and it is difficult to assess the statistical significance of the correlation coefficients presented here, the results are encouraging from physical viewpoint.

Barcilon, Albert; Weng, Hengyi

1990-01-01

400

Migraine and Stroke: “Vascular” Comorbidity  

PubMed Central

Several comorbidities are associated to migraine. Recent meta-analyses have consistently demonstrated a relationship between migraine and stroke, which is well-defined for ischemic stroke and migraine with aura (MA), even stronger in females on oral contraceptives or smokers. However, there seems to be no clear-cut association between stroke in migraineurs and the common vascular risk factors, at least in the young adult population. Migraineurs also run an increased risk of hemorrhagic stroke, while the association between migraine and cardiovascular disease remains poorly defined. Another aspect is the relationship between migraine and the presence of silent brain lesions. It has been demonstrated that there is an increased frequency of ischemic lesions in the white matter of migraineurs, especially silent infarcts in the posterior circulation territory in patients with at least 10 attacks per month. Although there is a higher prevalence of patent foramen ovale (PFO) in migraineurs, the relationship between migraine and PFO remains controversial and PFO closure is not a recommended procedure to prevent migraine. As an increased frequency of cervical artery dissections has been observed in migrainous patients, it has been hypothesized that migraine may represent a predisposing factor for cervical artery dissection. There still remains the question as to whether migraine should be considered a true “vascular disease” or if the comorbidity between migraine and cerebrovascular disease may have underlying shared risk factors or pathophysiological mechanisms. Although further studies are required to clarify this issue, current evidence supports a clinical management where MA patients should be screened for other concomitant vascular risk factors and treated accordingly. PMID:25339937

Guidetti, Donata; Rota, Eugenia; Morelli, Nicola; Immovilli, Paolo

2014-01-01

401

The Science of Negative Index Materials  

SciTech Connect

Metamaterials are designed to have structures that make available properties not found in Nature. Their unique properties (such as negative index of refraction, n) can be extended from GHz all the way to optical frequencies. We review the scaling properties of metamaterials that have been fabricated and give negative n and negative permeability, {mu}. It is found that most of the experimentally realized metamaterials have {lambda}/{alpha} between 2 (THz and optical region) and 12 (GHz region), where {lambda} is the operation wavelength and {alpha} is the size of the unit cell. The transmission losses for the experimental structures and the ratio {lambda}/{alpha} for the simulated structures are presented. Finally, a comparison of the different metamaterial designs (fishnet, cut and/or continuous wires, and split-ring resonators and wires) is given.

Costas M. Soukoulis; Jiangfeng Zhou; Thomas Koschny; Maria Kafesaki; Eleftherios N. Economou

2008-07-08

402

Water and solute permeability of rat lung caveolae: high permeabilities explained by acyl chain unsaturation  

Microsoft Academic Search

other integral membrane proteins were responsible for high perme- abilities, liposomes designed to mimic the lipids of the inner and outer leaflets of the caveolar membrane were made. Osmotic water perme- ability to both liposome compositions were determined and a com- bined inner\\/outer leaflet water permeability was calculated and found to be close to that of native caveolae at 1.58

Warren G. Hill; Eyad Almasri; W. Giovanni Ruiz; Gerard Apodaca; Mark L. Zeidel

2005-01-01

403

An integrated vascular management programme.  

PubMed

This paper discusses the development of an integrated approach for the creation and maintenance of arteriovenous access (AVA), under the direction of a dedicated vascular access surgeon in close cooperation with the haemodialysis staff, involving pre-operative imaging, anaesthetic and surgical techniques together with a post-operative graft surveillance programme, in order to maximize autogenous arteriovenous access (AAVA) construction (the preferred access for haemodialysis patients with end-stage renal disease), and to improve patency rates for AAVA and prosthetic arteriovenous access (PAVA). PMID:15835411

Shemesh, David; Olsha, Oded; Berelowitz, Daniel; Zigelman, Charles

2004-01-01

404

The game chromatic index and game coloring index of graphs  

E-print Network

The game chromatic index and game coloring index of graphs Leizhen Cai Department of Computer@math.nsysu.edu.tw May, 1998. y Abstract This paper discusses the game chromatic index and game coloring index of graphs. We prove that if a graph G is k-degenerate, then its game coloring index is at most #1;+ 3k 1

Zhu, Xuding

405

Circulating Mononuclear Progenitor Cells: Differential Roles for Subpopulations in Repair of Retinal Vascular Injury  

PubMed Central

Purpose. We examined effect on retinal vascular homing of exogenous CD34+ and CD14+ progenitor cells using mouse models of chronic (streptozotocin [STZ]-induced diabetes) and acute (ischemia–reperfusion [I/R]) ocular vascular injury. Methods. STZ-treated mice of short or long duration (?4, ?11 months) diabetes, along with age- and sex-matched controls, were given intravitreous injections of human CD34+ and CD14+ cells isolated from healthy or diabetic donors alone or in combination. I/R injured mice were given diabetic or nondiabetic CD34+ cells with mesenchymal stem cells (MSCs) or diabetic CD34+ cells manipulated by ex vivo fucosylation with ASC-101. Injected cells were localized by fluorescent immunocytochemistry, and the degree of retinal vascular colocalization quantified morphometrically. Permeability was assessed by fluorescent albumin leakage. Results. Diabetic CD14+ cells associated with vessels to a greater degree than diabetic CD34+ cells. Vascular permeability was reduced only by nondiabetic cells and only at the highest number of cells tested. Diabetic CD34+ cells consistently demonstrated reduced migration. There was a 2-fold or 4-fold increase over control in the specific localization of diabetic CD34+ cells within the vasculature when these cells were co-administered with MSCs or ex vivo fucosylated prior to injection, respectively. Conclusions. Diabetic CD14+ cells, unlike diabetic CD34+ cells, retain robust homing characteristics. CD34+ or CD14+ subsets rather than whole bone marrow or peripheral blood cells may prove more beneficial in autologous cell therapy for diabetics. Co-administration with MSCs or ex vivo fucosylation may enhance utility of CD34+ cells in cell therapy for diabetic ocular conditions like macular ischemia and retinal nonperfusion. PMID:23572102

Caballero, Sergio; Hazra, Sugata; Bhatwadekar, Ashay; Li Calzi, Sergio; Paradiso, Linda J.; Miller, Leonard P.; Chang, Lung-Ji; Kern, Timothy S.; Grant, Maria B.

2013-01-01

406

Reservoir permeability from seismic attribute analysis  

SciTech Connect

In case of porous fluid-saturated medium the Biot's poroelasticity theory predicts a movement of the pore fluid relative to the skeleton on seismic wave propagation through the medium. This phenomenon opens an opportunity for investigation of the flow properties of the hydrocarbon-saturated reservoirs. It is well known that relative fluid movement becomes negligible at seismic frequencies if porous material is homogeneous and well cemented. In this case the theory predicts an underestimated seismic wave velocity dispersion and attenuation. Based on Biot's theory, Helle et al. (2003) have numerically demonstrated the substantial effects on both velocity and attenuation by heterogeneous permeability and saturation in the rocks. Besides fluid flow effect, the effects of scattering (Gurevich, et al., 1997) play very important role in case of finely layered porous rocks and heterogeneous fluid saturation. We have used both fluid flow and scattering effects to derive a frequency-dependent seismic attribute which is proportional to fluid mobility and applied it for analysis of reservoir permeability.

Silin, Dmitriy; Goloshubin, G.; Silin, D.; Vingalov, V.; Takkand, G.; Latfullin, M.

2008-02-15

407

Efficient high-permeability fracturing offshore  

SciTech Connect

Offshore operators can more efficiently and effectively perform high-permeability and conventional hydraulic fracture treatments by blending treatment slurries under microprocessor control, adding undiluted acid on-the-fly, and altering sand concentrations and other slurry properties instantaneously. A two-skid system has been designed with these considerations in mind. The system, which can be shipped efficiently in ISO containers, has been tested on fluids up to 210-cp viscosity and can step or ramp sand concentrations up to a maximum of 20 lb/gal. All additives, including acid treatments, are added on-the-fly; leftover additives and acids may be stored for future jobs. The system may be applied in most conditions, including offshore wells requiring conventional or high-permeability fracture treatments and certain land-based wells in remote areas where a compact skid is needed. Three significant benefits have resulted from using the compact-skid system: offshore operators have been able to ship the skid system at 20% of shipping costs of non-ISO equipment; on-the-fly mixing has prevented material waste associated with batch-mixing; and volumes pumped on actual jobs have closely matched job designs. Data have been collected from several Gulf of Mexico jobs run with the two-part skid system that has been designed for conducting hydraulic fracture treatments from offshore rigs.

Phillipi, M.; Farabee, M.

1996-12-31

408

Effects of inorganic salts on tissue permeability.  

PubMed

Inorganic solutes are shown to alter the permeability of root and leaf tissues. Experiments with beet root tissues reveal that CaCl(2) decreases leakage of betacyanin from the tissue, that (NH(4))(2)SO(4) increases leakage, and that each salt can relieve the effects of the other. A comparison of cations and anions shows a range of effects with the various solutes. Experiments with Rumex obtusifolius L. leaf discs reveal that whereas CaCl(2) defers the development of senescence, (NH(4))(2)SO(4) hastens senescence and increases the leakage of materials out of the leaf discs. The solute effect on Rumex obtusifolius L. is prevented by gibberellin. CaCl(2) can relieve the (NH(4))(2)SO(4) effect. The results are interpreted as indicating that the inorganic solutes may serve to alter the permeability of membranes through alterations of interactions between water and macromolecules in the tissues; the interpretation is consistent with the evidence for opposite effects of Ca and NH(4), the effective concentrations being about 10(-3)m, and the reversibility of the effects of one solute by another of opposite stabilization-destabilization effect. PMID:16659643

Poovaiah, B W; Leopold, A C

1976-08-01

409

Determinants of vascular function in patients with type 2 diabetes  

PubMed Central

Background Type 2 diabetes mellitus (T2DM) is independently associated with an increased risk for cardiovascular diseases that is primarily due to the early development of advanced atherosclerotic vascular changes. The aim of our study was to investigate the predictors of vascular dysfunction in T2DM patients. Methods We studied 165 T2DM patients without known macrovascular or microvascular disease. Standard demographic (age, gender, cardiovascular risk factors, medications), clinical (body mass index, blood pressure) and laboratory (glucose, glycated hemoglobin, lipids, renal function) parameters were included in analyses. Brachial artery flow-mediated dilation (FMD), nitrate mediated dilation (NMD) and Carotid-Femoral Pulse Wave Velocity (PWV) were measured. Results Median age was 66 years and duration since T2DM diagnosis was 10 years, 70% were females and 79% hypertensives, while only 10% had a glycated hemoglobin <7%. FMD was positively associated with NMD (r 0.391, P?Vascular smooth muscle dysfunction and increased arterial stiffness were more prominent in older T2DM patients with hypertension. Worse glycemic control was associated with impaired vascular smooth muscle function. PMID:23062182

2012-01-01

410

Identification of molecular processes needed for vascular formation through transcriptome analysis of different vascular systems  

PubMed Central

Background Vascular system formation has been studied through molecular and genetic approaches in Arabidopsis, a herbaceous dicot that is used as a model system. Different vascular systems have developed in other plants such as crops and trees. Uncovering shared mechanisms underlying vascular development by transcriptome analysis of different vascular systems may help to transfer knowledge acquired from Arabidopsis to other economically important species. Results Conserved vascular genes and biological processes fundamental to vascular development were explored across various plants. Through comparative transcriptome analysis, 226 genes from Arabidopsis, 217 genes from poplar and 281 genes from rice were identified as constituting 107 conserved vascular gene groups. These gene groups are expressed mainly in vascular tissues and form a complex coexpression network with multiple functional connections. To date, only half of the groups have been experimentally investigated. The conserved vascular gene groups were classified into 9 essential processes for vascular development. 18 groups (17%) lack of annotations were classified as having unknown functions. Conclusion The study provides a map of fundamental biological processes conserved across different vascular systems. It identifies gaps in the experimental investigation of pathways active in vascular formation, which if explored, could lead to a more complete understanding of vascular development. PMID:23548001

2013-01-01

411

Protecting against vascular disease in brain  

PubMed Central

Endothelial cells exert an enormous influence on blood vessels throughout the circulation, but their impact is particularly pronounced in the brain. New concepts have emerged recently regarding the role of this cell type and mechanisms that contribute to endothelial dysfunction and vascular disease. Activation of the renin-angiotensin system plays a prominent role in producing these abnormalities. Both oxidative stress and local inflammation are key mechanisms that underlie vascular disease of diverse etiology. Endogenous mechanisms of vascular protection are also present, including antioxidants, anti-inflammatory molecules, and peroxisome proliferator-activated receptor-?. Despite their clear importance, studies of mechanisms that underlie cerebrovascular disease continue to lag behind studies of vascular biology in general. Identification of endogenous molecules and pathways that protect the vasculature may result in targeted approaches to prevent or slow the progression of vascular disease that causes stroke and contributes to the vascular component of dementia and Alzheimer's disease. PMID:21335467

2011-01-01

412

In vitro evaluation of carbon-nanotube-reinforced bioprintable vascular conduits  

NASA Astrophysics Data System (ADS)

Vascularization of thick engineered tissue and organ constructs like the heart, liver, pancreas or kidney remains a major challenge in tissue engineering. Vascularization is needed to supply oxygen and nutrients and remove waste in living tissues and organs through a network that should possess high perfusion ability and significant mechanical strength and elasticity. In this paper, we introduce a fabrication process to print vascular conduits directly, where conduits were reinforced with carbon nanotubes (CNTs) to enhance their mechanical properties and bioprintability. In vitro evaluation of printed conduits encapsulated in human coronary artery smooth muscle cells was performed to characterize the effects of CNT reinforcement on the mechanical, perfusion and biological performance of the conduits. Perfusion and permeability, cell viability, extracellular matrix formation and tissue histology were assessed and discussed, and it was concluded that CNT-reinforced vascular conduits provided a foundation for mechanically appealing constructs where CNTs could be replaced with natural protein nanofibers for further integration of these conduits in large-scale tissue fabrication.

Dolati, Farzaneh; Yu, Yin; Zhang, Yahui; De Jesus, Aribet M.; Sander, Edward A.; Ozbolat, Ibrahim T.

2014-04-01

413

A real-time impedance-based screening assay for drug-induced vascular leakage.  

PubMed

Vascular leakage is a serious side effect of therapies based on monoclonal antibodies or cytokines which may lead to life-threatening situations. With the steady increase of new drug development programs for large molecules, there is an urgent need for reliable tools to assess this potential liability of new medicines in a rapid and cost-effective manner. Using human umbilical vein endothelial cells (HUVECs) as a model for endothelium, we established an impedance-based assay measuring the integrity of the endothelial cell monolayer in real time. We could demonstrate that the HUVEC monolayer in our system was a relevant model as cells expressed major junctional proteins known to be responsible for maintaining tightness as well as receptors targeted by molecules known to induce vascular leakage in vivo. We assessed the time-dependent loss of barrier function using impedance and confirmed that signals obtained corresponded well to those from standard transwell assays. We assayed a series of reference molecules which led to the expected change of barrier integrity. A nonspecific cytotoxic effect could be excluded by using human fibroblasts as a nonresponder cell line. Finally, we could show reversibility of vascular permeability induced by histamine, IL-1?, or TNF-? by coincubation with established antagonists, further demonstrating relevance of this new model. Taken together, our results suggest that impedance in combination with HUVECs as a specific model can be applied to assess clinically relevant vascular leakage on an in vitro level. PMID:24385420

Kustermann, Stefan; Manigold, Tobias; Ploix, Corinne; Skubatz, Marion; Heckel, Tobias; Hinton, Heather; Weiser, Thomas; Singer, Thomas; Suter, Laura; Roth, Adrian

2014-04-01

414

Preliminary Evidence That High-Dose Vitamin C has a Vascular Disrupting Action in Mice  

PubMed Central

High intravenous doses of vitamin C (ascorbic acid) have been reported to benefit cancer patients, but the data are controversial and there is incomplete knowledge of what physiological mechanisms might be involved in any response. Vitamin C is taken up efficiently by cells expressing SVCT2 transporters and since vascular endothelial cells express SVCT2, we explored the hypothesis that administration of high-dose vitamin C (up to 5?g/kg) to mice might affect vascular endothelial function. A single administration of vitamin C to mice induced time- and dose-dependent increases in plasma concentrations of the serotonin metabolite 5-hydroxyindole acetic acid (5-HIAA), a marker for vascular disrupting effects. Responses were comparable to those for the tumor vascular disrupting agents, vadimezan and fosbretabulin. High-dose vitamin C administration decreased tumor serotonin concentrations, consistent with the release of serotonin from platelets and its metabolism to 5-HIAA. High-dose vitamin C also significantly increased the degree of hemorrhagic necrosis in tumors removed after 24?h, and significantly decreased tumor volume after 2?days. However, the effect on tumor growth was temporary. The results support the concept that vitamin C at high dose increases endothelial permeability, allowing platelets to escape and release serotonin. Plasma 5-HIAA concentrations could provide a pharmacodynamic biomarker for vitamin C effects in clinical studies.

Baguley, Bruce C.; Ding, Qi; Richardson, Emma

2014-01-01

415

MISR Thumbnail Index  

MISR Thumbnail Index   The Multi-angle Imaging SpectroRadiometer (MISR) was successfully launched into sun-synchronous polar orbit aboard Terra, ... America Oceans/Seas Arctic Ocean Atlantic Ocean Gulf of Mexico Indian Ocean ...

2014-08-01

416

CAD Centre - Index Searcher  

NSDL National Science Digital Library

A searchable index of the CAD Centre, a postgraduate teaching and research unit in design manufacture and engineering management, with research focused on design methods and computer support of the design process for engineering applications.

2007-10-11

417

The Index of Refraction  

NSDL National Science Digital Library

In this media-rich lesson plan, students explore the refraction of light at the boundary between materials: they learn about the refractive indices of various materials and measure the index of refraction of plastic or gelatin.

Foundation, Wgbh E.

2011-10-25

418

A complicated case of vascular Pythium insidiosum infection treated with limb-sparing surgery  

PubMed Central

INTRODUCTION Pythiosis is a serious life- and limb-threatening infection endemic to Thailand, but rarely seen in the Western hemisphere. Here, we present a unique case of vascular pythiosis initially managed with limb-sparing vascular bypass grafts complicated by a pseudoaneurysm in our repair. PRESENTATION OF CASE The patient is a 17 year-old Jamaican male with severe aplastic anemia. He sustained a minor injury to his left leg while fishing in Jamaica, which evolved to become an exquisitely tender inguinal swelling. His physical exam and imaging were significant for arteriovenous fistula with limb ischemia. Pathology obtained during surgery for an extra-anatomic vascular bypass showed extensive invasion by Pythium insidiosum. He later developed a pseudoaneurysm at the site of proximal anastomosis and required urgent intervention. DISCUSSION This patient presented with a rare, but classic case of vascular pythiosis, which was unrecognized at the time of presentation. A variety of therapeutic modalities have been used to treat this disease, including antibiotics, antifungals, and immunotherapy, but the ultimate management of vascular pythiosis is surgical source control. CONCLUSION A high index of suspicion in susceptible patients is needed for timely diagnosis of vascular pythiosis to achieve optimal source control. PMID:25194603

Pan, Jenny H.; Kerkar, Sid P.; Siegenthaler, Michael P.; Hughes, Marybeth; Pandalai, Prakash K.

2014-01-01

419

Calculation of large scale relative permeabilities from stochastic properties of the permeability field and fluid properties  

SciTech Connect

The paper describes the method and presents preliminary results for the calculation of homogenized relative permeabilities using stochastic properties of the permeability field. In heterogeneous media, the spreading of an injected fluid is mainly sue to the permeability heterogeneity and viscosity fingering. At large scale, when the heterogeneous medium is replaced by a homogeneous one, we need to introduce a homogenized (or pseudo) relative permeability to obtain the same spreading. Generally, is derived by using fine-grid numerical simulations (Kyte and Berry). However, this operation is time consuming and cannot be performed for all the meshes of the reservoir. We propose an alternate method which uses the information given by the stochastic properties of the field without any numerical simulation. The method is based on recent developments on homogenized transport equations (the {open_quotes}MHD{close_quotes} equation, Lenormand SPE 30797). The MHD equation accounts for the three basic mechanisms of spreading of the injected fluid: (1) Dispersive spreading due to small scale randomness, characterized by a macrodispersion coefficient D. (2) Convective spreading due to large scale heterogeneities (layers) characterized by a heterogeneity factor H. (3) Viscous fingering characterized by an apparent viscosity ration M. In the paper, we first derive the parameters D and H as functions of variance and correlation length of the permeability field. The results are shown to be in good agreement with fine-grid simulations. The are then derived a function of D, H and M. The main result is that this approach lead to a time dependent . Finally, the calculated are compared to the values derived by history matching using fine-grid numerical simulations.

Lenormand, R.; Thiele, M.R. [Institut Francais du Petrole, Rueil Malmaison (France)

1997-08-01

420

Mathematical Symbol Indexing  

Microsoft Academic Search

This paper addresses the indexing and retrieval of mathematical symbols from digitized documents. The proposed approach exploits\\u000a Shape Contexts (SC) to describe the shape of mathematical symbols. Indexed symbols are represented with a vector space-based\\u000a method that is grounded on SC clustering. We explore the use of the Self Organizing Map (SOM) to perform the clustering and\\u000a we compare several

Simone Marinai; Beatrice Miotti; Giovanni Soda

2009-01-01