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1

Vascular Permeability\\/Vascular Endothelial Growth Factor  

Microsoft Academic Search

The vascular permeability factor (VPF)\\/vascular endothelial growth factor (VEGF) family has more than seven members including\\u000a VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PlGF, and Trimeresurus flavoviridis (T. f.) svVEGFs. Except for VEGF-E and T.f. svVEGFs, all members are encoded in the mammalian genome and involved in angiogenesis and\\/or lymphangiogenesis. Among these\\u000a five gene products, VEGF-A (also known as VEGF and VPF)

Masabumi Shibuya

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

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

4

Pathophysiological consequences of VEGF-induced vascular permeability  

NASA Astrophysics Data System (ADS)

Although vascular endothelial growth factor (VEGF) induces angiogenesis, it also disrupts vascular barrier function in diseased tissues. Accordingly, VEGF expression in cancer and ischaemic disease has unexpected pathophysiological consequences. By uncoupling endothelial cell-cell junctions VEGF causes vascular permeability and oedema, resulting in extensive injury to ischaemic tissues after stroke or myocardial infarction. In cancer, VEGF-mediated disruption of the vascular barrier may potentiate tumour cell extravasation, leading to widespread metastatic disease. Therefore, by blocking the vascular permeability promoting effects of VEGF it may be feasible to reduce tissue injury after ischaemic disease and minimize the invasive properties of circulating tumour cells.

Weis, Sara M.; Cheresh, David A.

2005-09-01

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

Granzyme B Releases Vascular Endothelial Growth Factor from Extracellular Matrix and Induces Vascular Permeability  

PubMed Central

The formation of unstable, leaky neovessels underlies the pathogenesis of many chronic inflammatory diseases. Granzyme B (GZMB) is an immune-derived serine protease that accumulates in the extracellular matrix (ECM) during chronic inflammation and is capable of cleaving fibronectin (FN). Vascular endothelial growth factor (VEGF) is a potent vascular permeabilizing agent that is sequestered in the ECM through its interaction with FN. As GZMB levels are elevated in chronic inflammatory diseases that are associated with increased vascular permeability, the role of GZMB in the regulation of VEGF bioavailability and vascular permeability were assessed. Methods and Results GZMB was added to either VEGF-bound to FN or VEGF-bound to endothelial cell (EC)-derived ECM. Supernatants containing released VEGF were assessed to determine VEGF activity by treating EC and evaluating VEGF receptor-2 (VEGFR2) phosphorylation. GZMB released VEGF from both FN and from EC-derived matrix, while GZMB inhibition prevented FN cleavage and VEGF release. GZMB-mediated VEGF release resulted in significant phosphorylation of VEGFR2. The role of GZMB-mediated VEGF release in altering vascular permeability was also assessed in vivo using a Miles/Evan’s Blue permeability assay. GZMB induced a significant VEGF-dependent increase in vascular permeability in vivo that was reduced in the presence of an anti-VEGF neutralizing antibody. Inflammatory-mediated vascular leakage was also assessed in GZMB-KO mice using a delayed-type hypersensitivity model. GZMB-KO mice exhibited reduced microvascular leakage compared to C57\\B6 controls. Conclusions GZMB increases vascular permeability in part through the proteolytic release of ECM-sequestered VEGF leading to VEGFR2 activation and increased vascular permeability in vivo. These findings present a novel role for GZMB as a modulator of vascular response during chronic inflammation. PMID:24791744

Hendel, Alon; Hsu, Ivy; Granville, David J.

2014-01-01

7

Soluble neuropilin targeted to the skin inhibits vascular permeability  

Microsoft Academic Search

Neuropilin 1 (NRP1) is a co-receptor for vascular endothelial growth factor (VEGF165), an inducer of vascular permeability and angiogenesis. Numerous physiological factors enhance VEGF expression and function\\u000a but only a few have been shown to be negative regulators. Previously, we have shown that the naturally occurring soluble form\\u000a of NRP1 (sNRP1) inhibits binding of VEGF165 to endothelial cells in vitro

Roni Mamluk; Michael Klagsbrun; Michael Detmar; Diane R. Bielenberg

2005-01-01

8

Atrial natriuretic factor increases vascular permeability  

NASA Technical Reports Server (NTRS)

An increase in central blood volume in microgravity may result in increased plasma levels of atrial natriuretic factor (ANF). In this study, it was determined whether ANF increases capillary permeability to plasma protein. Conscious, bilaterally nephrectomized male rats were infused with either saline, ANF + saline, or hexamethonium + saline over 2 h following bolus injections of (I-125)-albumin and (C-14)-dextran of similar molecular size. Blood pressure was monitored, and serial determinations of hematocrits were made. Animals infused with 1.0 microg/kg per min ANF had significantly higher hematocrits than animals infused with saline vehicle. Infusion of ANF increased the extravasation of (I-125)-albumin, but not (C-14)-dextran from the intravascular compartment. ANF also induced a depressor response in rats, but the change in blood pressure did not account for changes in capillary permeability to albumin; similar depressor responses induced by hexamethonium were not accompanied by increased extravasation of albumin from the intravascular compartment. ANF may decrease plasma volume by increasing permeability to albumin, and this effect of ANF may account for some of the signs and symptoms of space motion sickness.

Lockette, Warren; Brennaman, Bruce

1990-01-01

9

Atrial natriuretic factor increases vascular permeability  

SciTech Connect

An increase in central blood volume in microgravity may result in increased plasma levels of atrial natriuretic factor (ANF). Since elevations in plasma ANF are found in clinical syndromes associated with edema, and since space motion sickness induced by microgravity is associated with an increase in central blood volume and facial edema, we determined whether ANF increases capillary permeability to plasma protein. Conscious, bilaterally nephrectomized male rats were infused with either saline, ANF + saline, or hexamethonium + saline over 2 h following bolus injections of 125I-albumin and 14C-dextran of similar molecular size. Blood pressure was monitored and serial determinations of hematocrits were made. Animals infused with 1.0 micrograms.kg-1.min-1 ANF had significantly higher hematocrits than animals infused with saline vehicle. Infusion of ANF increased the extravasation of 125I-albumin, but not 14C-dextran from the intravascular compartment. ANF also induced a depressor response in rats, but the change in blood pressure did not account for changes in capillary permeability to albumin; similar depressor responses induced by hexamethonium were not accompanied by increased extravasation of albumin from the intravascular compartment. ANF may decrease plasma volume by increasing permeability to albumin, and this effect of ANF may account for some of the signs and symptoms of space motion sickness.

Lockette, W.; Brennaman, B. (Wayne State Univ. School of Medicine, Detroit, MI (USA))

1990-12-01

10

Wogonin influences vascular permeability via Wnt/?-catenin pathway.  

PubMed

Wogonin, a flavone from the root of Scutellaria baicalensis Georgi, has shown various biological activities. In our previous study, it was confirmed that wogonin could decrease the expression of hypoxia-inducible factor-1? (HIF-1?) by affecting its stability under hypoxia. However, it is still unknown whether wogonin could influence Wnt/?-catenin pathway under hypoxia. In this study, we found that wogonin disrupted Wnt/?-catenin signaling and reduced the secretion of vascular endothelial growth factor (VEGF, also known as vascular permeability factor, VPF), which increased vascular permeability in certain diseases. It was found that wogonin suppressed HUVECs hyperactivity and actin remodeling induced by hypoxia, inhibited transendothelial cell migration of the human breast carcinoma cell MDA-MB-231 and the extravasated Evans in vivo Miles vascular permeability assay. Wogonin-treated cells showed a decrease in the expression of Wnt protein and its co-receptors, as well as a parallel increase in the expression of Axin and GSK-3? in degradation complex, leading to degradation of ?-catenin. In addition, wogonin promoted the binding between Axin and ?-catenin, increased ubiquitination of ?-catenin and promoted its degradation. Interestingly, wogonin decreased the expression of TCF-1, TCF-3, and LEF-1 and inhibited nuclear accumulation of ?-catenin as well as the binding of ?-catenin and TCF-1, TCF-3, or LEF-1. All of the above results showed that wogonin could inhibit the expression of VEGF, which is an important factor regulated by ?-catenin. Taken together, the results suggested that wogonin was a potent inhibitor of Wnt/?-catenin and influenced vascular permeability, and this might provide new therapeutics in certain diseases. © 2013 Wiley Periodicals, Inc. PMID:24136474

Song, Xiuming; Zhou, Yuxin; Zhou, Mi; Huang, Yujie; Li, Zhiyu; You, Qidong; Lu, Na; Guo, Qinglong

2013-10-17

11

Human Mesenchymal Stem Cells Inhibit Vascular Permeability by Modulating Vascular Endothelial Cadherin/?-Catenin Signaling  

PubMed Central

The barrier formed by endothelial cells (ECs) plays an important role in tissue homeostasis by restricting passage of circulating molecules and inflammatory cells. Disruption of the endothelial barrier in pathologic conditions often leads to uncontrolled inflammation and tissue damage. An important component of this barrier is adherens junctions, which restrict paracellular permeability. The transmembrane protein vascular endothelial (VE)-cadherin and its cytoplasmic binding partner ?-catenin are major components of functional adherens junctions. We show that mesenchymal stem cells (MSCs) significantly reduce endothelial permeability in cocultured human umbilical vascular endothelial cells (HUVECs) and following exposure to vascular endothelial growth factor, a potent barrier permeability-enhancing agent. When grown in cocultures with HUVECs, MSCs increased VE-cadherin levels and enhanced recruitment of both VE-cadherin and ?-catenin to the plasma membrane. Enhanced membrane localization of ?-catenin was associated with a decrease in ?-catenin-driven gene transcription. Disruption of the VE-cadherin/?-catenin interaction by overexpressing a truncated VE-cadherin lacking the ?-catenin interacting domain blocked the permeability-stabilizing effect of MSCs. Interestingly, a conditioned medium from HUVEC-MSC cocultures, but not from HUVEC or MSC cells cultured alone, significantly reduced endothelial permeability. In addition, intravenous administration of MSCs to brain-injured rodents reduced injury-induced enhanced blood–brain barrier permeability. Similar to the effect on in vitro cultures, this stabilizing effect on blood–brain barrier function was associated with increased expression of VE-cadherin. Taken together, these results identify a putative mechanism by which MSCs can modulate vascular EC permeability. Further, our results suggest that the mediator(s) of these vascular protective effects is a secreted factor(s) released as a result of direct MSC–EC interaction. PMID:20446815

Khakoo, Aarif Y.; Zhao, Jing; Jimenez, Fernando; Gerber, Michael H.; Harting, Matthew; Redell, John B.; Grill, Raymond; Matsuo, Yoichi; Guha, Sushovan; Cox, Charles S.; Reitz, Marvin S.; Holcomb, John B.; Dash, Pramod K.

2011-01-01

12

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

13

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

14

Tumor vascular permeability factor stimulates endothelial cell growth and angiogenesis.  

PubMed Central

Vascular permeability factor (VPF) is an Mr 40-kD protein that has been purified from the conditioned medium of guinea pig line 10 tumor cells grown in vitro, and increases fluid permeability from blood vessels when injected intradermally. Addition of VPF to cultures of vascular endothelial cells in vitro unexpectedly stimulated cellular proliferation. VPF promoted the growth of new blood vessels when administered into healing rabbit bone grafts or rat corneas. The identity of the growth factor activity with VPF was established in four ways: (a) the molecular weight of the activity in preparative SDS-PAGE was the same as VPF (Mr approximately 40 kD); (b) multiple isoforms (pI greater than or equal to 8) for both VPF and the growth-promoting activity were observed; (c) a single, unique NH2-terminal amino acid sequence was obtained; (d) both growth factor and permeability-enhancing activities were immunoadsorbed using antipeptide IgG that recognized the amino terminus of VPF. Furthermore, 125I-VPF was shown to bind specifically and with high affinity to endothelial cells in vitro and could be chemically cross-linked to a high-molecular weight cell surface receptor, thus demonstrating a mechanism whereby VPF can interact directly with endothelial cells. Unlike other endothelial cell growth factors, VPF did not stimulate [3H]thymidine incorporation or promote growth of other cell types including mouse 3T3 fibroblasts or bovine smooth muscle cells. VPF, therefore, appears to be unique in its ability to specifically promote increased vascular permeability, endothelial cell growth, and angio-genesis. Images PMID:2478587

Connolly, D T; Heuvelman, D M; Nelson, R; Olander, J V; Eppley, B L; Delfino, J J; Siegel, N R; Leimgruber, R M; Feder, J

1989-01-01

15

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

16

Time-dependent vascular regression and permeability changes in established human tumor xenografts induced by an anti-vascular endothelial growth factor/vascular permeability factor?antibody  

PubMed Central

The hyperpermeability of tumor vessels to macromolecules, compared with normal vessels, is presumably due to vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) released by neoplastic and/or host cells. In addition, VEGF/VPF is a potent angiogenic factor. Removal of this growth factor may reduce the permeability and inhibit tumor angiogenesis. To test these hypotheses, we transplanted a human glioblastoma (U87), a human colon adenocarcinoma (LS174T), and a human melanoma (P-MEL) into two locations in immunodeficient mice: the cranial window and the dorsal skinfold chamber. The mice bearing vascularized tumors were treated with a bolus (0.2 ml) of either a neutralizing antibody (A4.6.1) (492 ?g/ml) against VEGF/VPF or PBS (control). We found that tumor vascular permeability to albumin in antibody-treated groups was lower than in the matched controls and that the effect of the antibody was time-dependent and influenced by the mode of injection. Tumor vascular permeability did not respond to i.p. injection of the antibody until 4 days posttreatment. However, the permeability was reduced within 6 h after i.v. injection of the same amount of antibody. In addition to the reduction in vascular permeability, the tumor vessels became smaller in diameter and less tortuous after antibody injections and eventually disappeared from the surface after four consecutive treatments in U87 tumors. These results demonstrate that tumor vascular permeability can be reduced by neutralization of endogenous VEGF/VPF and suggest that angiogenesis and the maintenance of integrity of tumor vessels require the presence of VEGF/VPF in the tissue microenvironment. The latter finding reveals a new mechanism of tumor vessel regression—i.e., blocking the interactions between VEGF/VPF and endothelial cells or inhibiting VEGF/VPF synthesis in solid tumors causes dramatic reduction in vessel diameter, which may block the passage of blood elements and thus lead to vascular regression. PMID:8962129

Yuan, Fan; Chen, Yi; Dellian, Marc; Safabakhsh, Nina; Ferrara, Napoleone; Jain, Rakesh K.

1996-01-01

17

VEGF-induced vascular permeability is mediated by FAK  

PubMed Central

SUMMARY Endothelial cells (ECs) form cell-cell adhesive junctional structures maintaining vascular integrity. This barrier is dynamically regulated by vascular endothelial growth factor (VEGF) receptor signaling. We created an inducible knockin mouse model to study the contribution of the integrin-associated focal adhesion tyrosine kinase (FAK) signaling on vascular function. Here we show that genetic or pharmacological FAK inhibition in ECs prevents VEGF-stimulated permeability downstream of VEGF receptor or Src tyrosine kinase activation in vivo. VEGF promotes tension-independent FAK activation, rapid FAK localization to cell-cell junctions, binding of the FAK FERM domain to the vascular endothelial cadherin (VE-cadherin) cytoplasmic tail, and direct FAK phosphorylation of ?-catenin at tyrosine-142 (Y142) facilitating VE-cadherin-?-catenin dissociation and EC junctional breakdown. Kinase inhibited FAK is in a closed conformation that prevents VE-cadherin association and limits VEGF-stimulated ?-catenin Y142 phosphorylation. Our studies establish a role for FAK as an essential signaling switch within ECs regulating adherens junction dynamics. PMID:22264731

Chen, Xiao Lei; Nam, Ju-Ock; Jean, Christine; Lawson, Christine; Walsh, Colin T.; Goka, Erik; Lim, Ssang-Taek; Tomar, Alok; Tanjoni, Isabelle; Uryu, Sean; Guan, Jun-Lin; Acevedo, Lisette M.; Weis, Sara M.; Cheresh, David A.; Schlaepfer, David D.

2011-01-01

18

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

19

Vascular permeability in a human tumour xenograft: molecular charge dependence  

PubMed Central

Molecular charge is one of the main determinants of transvascular transport. There are, however, no data available on the effect of molecular charge on microvascular permeability of macromolecules in solid tumours. To this end, we measured tumour microvascular permeability to different proteins having similar size but different charge. Measurements were performed in the human colon adenocarcinoma LS174T transplanted in transparent dorsal skinfold chambers in severe combined immunodeficient (SCID) mice. Bovine serum albumin (BSA) and IgG were fluorescently labelled and were either cationized by conjugation with hexamethylenediamine or anionized by succinylation. The molecules were injected i.v. and the fluorescence in tumour tissue was quantified by intravital fluorescence microscopy. The fluorescence intensity and pharmacokinetic data were used to calculate the microvascular permeability. We found that tumour vascular permeability of cationized BSA (pI-range: 8.6–9.1) and IgG (pI: 8.6–9.3) was more than two-fold higher (4.25 and 4.65 × 10?7cm s?1) than that of the anionized BSA (pI ? 2.0) and IgG (pI: 3.0–3.9; 1.11 and 1.93 × 10?7cm s?1, respectively). Our results indicate that positively charged molecules extravasate faster in solid tumours compared to the similar-sized compounds with neutral or negative charges. However, the plasma clearance of cationic molecules was ?2 × faster than that of anionic ones, indicating that the modification of proteins enhances drug delivery to normal organs as well. Therefore, caution should be exercised when such a strategy is used to improve drug and gene delivery to solid tumours. © 2000 Cancer Research Campaign PMID:10789717

Dellian, M; Yuan, F; Trubetskoy, V S; Torchilin, V P; Jain, R K

2000-01-01

20

Vascular permeability in diabetics and implications for therapy.  

PubMed

Several factors contribute to increased vascular permeability in diabetes mellitus, namely hyperglycaemia leading to increased production of diacylglycerol and thence protein kinase C, non-enzymatic glucosylation generating free radicals and lipid peroxides, sorbitol formation, loss of endothelial cell surface heparan sulphates, and the action of arachidonate derivatives that affect endothelial cell contractility. In view of the importance of oxidative damage, serious consideration must be given to therapeutic regimens that utilise vitamin E or ascorbic acid or D-myoinositol. Probucol is an available antioxidant whose properties have received insufficient attention. The oleate of monounsaturated oil diets is likewise anti-oxidant. Furthermore there is a possibility of replacing lost surface heparan sulphates. PMID:7924872

Wardle, E N

1994-04-01

21

Effect of leukotriene receptor antagonists on vascular permeability during endotoxic shock  

SciTech Connect

Evidence has accumulated that sulfidopeptide leukotrienes are significant pathogenic mediators of certain hematologic and hemodynamic sequelae of endotoxic shock. In the present study, the effects of a selective LTD4/E4 receptor antagonist, LY171883 (LY), or a selective LTD4 receptor antagonist, SKF-104353 (SKF), were assessed on splanchnic and pulmonary localization of 99mTechnetium-labeled human serum albumin (99mTc-HSA) in acute endotoxic shock in the rat. Dynamic gamma camera imaging of heart (H), midabdominal (GI), and lung regions of interest generated time activity curves for baseline and at 5-35 min after Salmonella enteritidis endotoxin (10 mg/kg, i.v.). Slopes of GI/H and lung/H activity (permeability index, GI/H or lung/H X 10(-3)/min) provided indices of intestinal and lung localization. Rats received LY (30 mg/kg, i.v.), LY vehicle (LY Veh), SKF (10 mg/kg), or SKF vehicle (SK Veh) 10 min prior to endotoxin or endotoxin vehicle. In rats receiving the LY Veh and endotoxin (n = 8) or SKF Veh and endotoxin (n = 12), the splanchnic permeability indices to 99mTc-HSA were increased 11.2-fold and 5.1-fold, respectively (P less than 0.05) compared to vehicle control groups not given endotoxin (n = 5). Pulmonary permeability index for 99mTc-HSA was increased (P less than 0.05) to a lesser extent (3.2-fold) by endotoxin compared to vehicle controls. Pretreatment with SKF reduced the mesenteric permeability index to control levels (P less than 0.05) during the 5-35 min time interval post-endotoxin. LY reduced the mesenteric permeability index by 70%. Pulmonary relative permeability to 99mTc-HSA was not affected by LY pretreatment. Both splanchnic and lung relative permeability to the isotope was transient; at 135-225 min post-endotoxin, splanchnic localization of 99mTc-HSA (n = 4) was not significantly different from vehicle controls in these vascular beds.

Cook, J.A.; Li, E.J.; Spicer, K.M.; Wise, W.C.; Halushka, P.V. (Medical Univ. of South Carolina, Charleston (USA))

1990-11-01

22

Vascular permeability and late radiation fibrosis in mouse lung  

SciTech Connect

It has been suggested that fibrosis which developed after irradiation is caused by increases in vascular permeability. Plasma proteins leak into irradiated tissue where fibrinogen may be converted into fibrin which is gradually replaced by fibrous tissue. Vascular and fibrotic changes in mouse lung were investigated after X irradiation of the right hemithorax. Blood volume and accumulation of extravascular proteins were measured using indium (/sup 111/In)-labeled red cells, iodinated (/sup 131/I) albumin, and iodinated (/sup 125/I) fibrinogen. During the first few months after X rays, lung blood volume decreased to a plateau which depended on radiation dose (10-25 Gy). Small increases in extravascular albumin and fibrinogen occurred at 1-12 weeks after 10-25 Gy. Hydroxyproline per gram of dry irradiated lung was increased at 18 weeks after 15-25 Gy. Support for the hypothesis was that hydroxyproline per gram only increased after X-ray doses which caused marked extravasation of protein. There was no evidence, however, for deposition of /sup 125/I-fibrin or for a gradual increase in fibrosis corresponding to the prolonged excess of extravascular protein.

Law, M.P.

1985-07-01

23

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

Microsoft Academic Search

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 !-galactosyl epitopes and expressing the L-fucose moiety in the glycocalyx; the poly-N-lactosamine glycan backbone is common

Paul L. Debbage; Elisabeth Sölder; Sonja Seidl; Peter Hutzler; Beate Hugl; Dietmar Öfner; Alfons Kreczy

2001-01-01

24

Vascular endothelial growth factor regulates angiogenesis and vascular permeability in Kaposi's sarcoma.  

PubMed Central

Abundant vasculature with increased permeability is a prominent histological feature of Kaposi's sarcoma (KS), a multifocal, cytokine-regulated tumor. Here we report on the role of vascular endothelial growth factor (VEGF) in AIDS-KS angiogenesis and vascular permeability. We demonstrate that different cytokines, which were previously shown to be active in KS development, modulate VEGF expression in KS spindle cells and cooperate with VEGF on the functional level. Northern blot analysis as well as studies on single cells using in situ hybridization revealed that VEGF expression in cultivated AIDS-KS spindle cells is up-regulated by platelet-derived growth factor-B and interleukin-1 beta. Western blot and enzyme-linked immunosorbent assay analysis of cell culture supernatants demonstrated that the VEGF protein is secreted by stimulated AIDS-KS spindle cells in sufficiently high amounts to activate proliferation of human dermal microvascular endothelial cells. Basic fibroblast growth factor did not increase VEGF expression but acted synergistically with VEGF in the induction of angiogenic KS-like lesions in a mouse model in vivo. Angiogenesis and cellularity of KS-like lesions were clearly increased when both factors were injected simultaneously into the flanks of mice, compared with separate injection of each factor. A comparable angiogenic reaction as obtained by simultaneous injection of basic fibroblast growth factor and VEGF was observed when cell culture supernatants of AIDS-KS spindle cells were used for these experiments. Finally, analysis of primary human AIDS-KS lesions revealed that high amounts of VEGF mRNA and protein were present in KS spindle cells in vivo. These data provide evidence that VEGF, in concert with platelet-derived growth factor-B, interleukin-1 beta, and basic fibroblast growth factor, is a key mediator of angiogenesis and vascular permeability in KS lesions in vivo. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 PMID:8952523

Cornali, E.; Zietz, C.; Benelli, R.; Weninger, W.; Masiello, L.; Breier, G.; Tschachler, E.; Albini, A.; Stürzl, M.

1996-01-01

25

Predominant role of endothelial nitric oxide synthase in vascular endothelial growth factor-induced angiogenesis and vascular permeability  

PubMed Central

Nitric oxide (NO) plays a critical role in vascular endothelial growth factor (VEGF)-induced angiogenesis and vascular hyperpermeability. However, the relative contribution of different NO synthase (NOS) isoforms to these processes is not known. Here, we evaluated the relative contributions of endothelial and inducible NOS (eNOS and iNOS, respectively) to angiogenesis and permeability of VEGF-induced angiogenic vessels. The contribution of eNOS was assessed by using an eNOS-deficient mouse, and iNOS contribution was assessed by using a selective inhibitor [l-N6-(1-iminoethyl) lysine, l-NIL] and an iNOS-deficient mouse. Angiogenesis was induced by VEGF in type I collagen gels placed in the mouse cranial window. Angiogenesis, vessel diameter, blood flow rate, and vascular permeability were proportional to NO levels measured with microelectrodes: Wild-type (WT) ? WT with l-NIL or iNOS?/? > eNOS?/? ? eNOS?/? with l-NIL. The role of NOS in VEGF-induced acute vascular permeability increase in quiescent vessels also was determined by using eNOS- and iNOS-deficient mice. VEGF superfusion significantly increased permeability in both WT and iNOS?/? mice but not in eNOS?/? mice. These findings suggest that eNOS plays a predominant role in VEGF-induced angiogenesis and vascular permeability. Thus, selective modulation of eNOS activity is a promising strategy for altering angiogenesis and vascular permeability in vivo. PMID:11226286

Fukumura, Dai; Gohongi, Takeshi; Kadambi, Ananth; Izumi, Yotaro; Ang, Jennifer; Yun, Chae-Ok; Buerk, Donald G.; Huang, Paul L.; Jain, Rakesh K.

2001-01-01

26

Tumor Vascular Permeability to a Nanoprobe Correlates to Tumor-Specific Expression Levels of Angiogenic Markers  

PubMed Central

Background Vascular endothelial growth factor (VEGF) receptor-2 is the major mediator of the mitogenic, angiogenic, and vascular hyperpermeability effects of VEGF on breast tumors. Overexpression of VEGF and VEGF receptor-2 is associated with the degree of pathomorphosis of the tumor tissue and unfavorable prognosis. In this study, we demonstrate that non-invasive quantification of the degree of tumor vascular permeability to a nanoprobe correlates with the VEGF and its receptor levels and tumor growth. Methodology/Principal Findings We designed an imaging nanoprobe and a methodology to detect the intratumoral deposition of a 100 nm-scale nanoprobe using mammography allowing measurement of the tumor vascular permeability in a rat MAT B III breast tumor model. The tumor vascular permeability varied widely among the animals. Notably, the VEGF and VEGF receptor-2 gene expression of the tumors as measured by qRT-PCR displayed a strong correlation to the imaging-based measurements of vascular permeability to the 100 nm-scale nanoprobe. This is in good agreement with the fact that tumors with high angiogenic activity are expected to have more permeable blood vessels resulting in high intratumoral deposition of a nanoscale agent. In addition, we show that higher intratumoral deposition of the nanoprobe as imaged with mammography correlated to a faster tumor growth rate. This data suggest that vascular permeability scales to the tumor growth and that tumor vascular permeability can be a measure of underlying VEGF and VEGF receptor-2 expression in individual tumors. Conclusions/Significance This is the first demonstration, to our knowledge, that quantitative imaging of tumor vascular permeability to a nanoprobe represents a form of a surrogate, functional biomarker of underlying molecular markers of angiogenesis. PMID:19513111

Karathanasis, Efstathios; Chan, Leslie; Karumbaiah, Lohitash; McNeeley, Kathleen; D'Orsi, Carl J.; Annapragada, Ananth V.; Sechopoulos, Ioannis; Bellamkonda, Ravi V.

2009-01-01

27

Progesterone receptor in the vascular endothelium triggers physiological uterine permeability preimplantation.  

PubMed

Vascular permeability is frequently associated with inflammation and is triggered by a cohort of secreted permeability factors such as vascular endothelial growth factor (VEGF). Here, we show that the physiological vascular permeability that precedes implantation is directly controlled by progesterone receptor (PR) and is independent of VEGF. Global or endothelial-specific deletion of PR blocks physiological vascular permeability in the uterus, whereas misexpression of PR in the endothelium of other organs results in ectopic vascular leakage. Integration of an endothelial genome-wide transcriptional profile with chromatin immunoprecipitation sequencing revealed that PR induces an NR4A1 (Nur77/TR3)-dependent transcriptional program that broadly regulates vascular permeability in response to progesterone. Silencing of NR4A1 blocks PR-mediated permeability responses, indicating a direct link between PR and NR4A1. This program triggers concurrent suppression of several junctional proteins and leads to an effective, timely, and venous-specific regulation of vascular barrier function that is critical for embryo implantation. PMID:24485460

Goddard, Lauren M; Murphy, Thomas J; Org, Tönis; Enciso, Josephine M; Hashimoto-Partyka, Minako K; Warren, Carmen M; Domigan, Courtney K; McDonald, Austin I; He, Huanhuan; Sanchez, Lauren A; Allen, Nancy C; Orsenigo, Fabrizio; Chao, Lily C; Dejana, Elisabetta; Tontonoz, Peter; Mikkola, Hanna K A; Iruela-Arispe, M Luisa

2014-01-30

28

Semaphorin3A elevates vascular permeability and contributes to cerebral ischemia-induced brain damage  

PubMed Central

Semaphorin 3A (Sema3A) increased significantly in mouse brain following cerebral ischemia. However, the role of Sema3A in stroke brain remains unknown. Our aim was to determine wether Sema3A functions as a vascular permeability factor and contributes to ischemic brain damage. Recombinant Sema3A injected intradermally to mouse skin, or stereotactically into the cerebral cortex, caused dose- and time-dependent increases in vascular permeability, with a degree comparable to that caused by injection of a known vascular permeability factor vascular endothelial growth factor receptors (VEGF). Application of Sema3A to cultured endothelial cells caused disorganization of F-actin stress fibre bundles and increased endothelial monolayer permeability, confirming Sema3A as a permeability factor. Sema3A-mediated F-actin changes in endothelial cells were through binding to the neuropilin2/VEGFR1 receptor complex, which in turn directly activates Mical2, a F-actin modulator. Down-regulation of Mical2, using specific siRNA, alleviated Sema3A-induced F-actin disorganization, cellular morphology changes and endothelial permeability. Importantly, ablation of Sema3A expression, cerebrovascular permeability and brain damage were significantly reduced in response to transient middle cerebral artery occlusion (tMCAO) and in a mouse model of cerebral ischemia/haemorrhagic transformation. Together, these studies demonstrated that Sema3A is a key mediator of cerebrovascular permeability and contributes to brain damage caused by cerebral ischemia. PMID:25601765

Hou, Sheng Tao; Nilchi, Ladan; Li, Xuesheng; Gangaraju, Sandhya; Jiang, Susan X.; Aylsworth, Amy; Monette, Robert; Slinn, Jacqueline

2015-01-01

29

Resistance of essential fatty acid-deficient rats to endotoxin-induced increases in vascular permeability  

SciTech Connect

Resistance to endotoxin in essential fatty acid-deficient (EFAD) rats is associated with reduced synthesis of certain arachidonic acid metabolites. It was hypothesized that EFAD rats would manifest decreased vascular permeability changes during endotoxemia as a consequence of reduced arachidonic acid metabolism. To test this hypothesis, changes in hematocrit (HCT) and mesenteric localization rate of technetium-labeled human serum albumin (99mTc-HSA) and red blood cells (99mTc-RBC) were assessed in EFAD and normal rats using gamma-camera imaging. Thirty minutes after Salmonella enteritidis endotoxin, EFAD rats exhibited less hemoconcentration as determined by % HCT than normal rats. Endotoxin caused a less severe change in permeability index in the splanchnic region in EFAD rats than in normal rats (1.2 +/- 0.6 x 10(-3)min-1 vs. 4.9 +/- 1.7 x 10(-3)min-1 respectively, P less than 0.05). In contrast to 99mTc-HSA, mesenteric localization of 99mTc-RBC was not changed by endotoxin in control or EFAD rats. Supplementation with ethyl-arachidonic acid did not enhance susceptibility of EFAD rats to endotoxin-induced splanchnic permeability to 99mTc-HSA. Leukotrienes have been implicated as mediators of increased vascular permeability in endotoxin shock. Since LTC3 formation has been reported to be increased in EFA deficiency, we hypothesized that LTC3 may be less potent than LTC4. Thus the effect of LTC3 on mean arterial pressure and permeability was compared to LTC4 in normal rats. LTC3-induced increases in peak mean arterial pressure were less than LTC4 at 10 micrograms/kg (39 +/- 5 mm Hg vs. 58 +/- 4 mm Hg respectively, P less than 0.05) and at 20 micrograms/kg (56 +/- 4 mm Hg vs. 75 +/- 2 mm Hg respectively, P less than 0.05). LY171883 (30 mg/kg), an LTD4/E4 receptor antagonist, attenuated the pressor effect of LTC4, LTD4, and LTC3.

Li, E.J.; Cook, J.A.; Spicer, K.M.; Wise, W.C.; Rokach, J.; Halushka, P.V. (Medical Univ. of South Carolina, Charleston (USA))

1990-06-01

30

Urokinase plasminogen activator regulates pulmonary arterial contractility and vascular permeability in mice.  

PubMed

The concentration of urokinase plasminogen activator (uPA) is elevated in pathological settings such as acute lung injury, where pulmonary arterial contractility and permeability are disrupted. uPA limits the accretion of fibrin after injury. Here we investigated whether uPA also regulates pulmonary arterial contractility and permeability. Contractility was measured using isolated pulmonary arterial rings. Pulmonary blood flow was measured in vivo by Doppler and pulmonary vascular permeability, according to the extravasation of Evans blue. Our data show that uPA regulates the in vitro pulmonary arterial contractility induced by phenylephrine in a dose-dependent manner through two receptor-dependent pathways, and regulates vascular contractility and permeability in vivo. Physiological concentrations of uPA (?1 nM) stimulate the contractility of pulmonary arterial rings induced by phenylephrine through the low-density lipoprotein receptor-related protein receptor. The procontractile effect of uPA is independent of its catalytic activity. At pathophysiological concentrations, uPA (20 nM) inhibits contractility and increases vascular permeability. The inhibition of vascular contractility and increase of vascular permeability is mediated through a two-step process that involves docking to N-methyl-d-aspartate receptor-1 (NMDA-R1) on pulmonary vascular smooth muscle cells, and requires catalytic activity. Peptides that specifically inhibit the docking of uPA to NMDA-R, or the uPA variant with a mutated receptor docking site, abolished both the effects of uPA on vascular contractility and permeability, without affecting its catalytic activity. These data show that uPA, at concentrations found under pathological conditions, reduces pulmonary arterial contractility and increases permeability though the activation of NMDA-R1. The selective inhibition of NMDAR-1 activation by uPA can be accomplished without a loss of fibrinolytic activity. PMID:21617202

Nassar, Taher; Yarovoi, Serge; Fanne, Rami Abu; Waked, Otailah; Allen, Timothy C; Idell, Steven; Cines, Douglas B; Higazi, Abd Al-Roof

2011-11-01

31

Heterogeneity of the Angiogenic Response Induced in Different Normal Adult Tissues by Vascular Permeability Factor\\/Vascular Endothelial Growth Factor  

Microsoft Academic Search

Vascular permeability factor\\/vascular endothelial growth factor (VPF\\/VEGF) is an angiogenic cytokine with potential for the treatment of tissue ischemia. To investigate the properties of the new blood vessels induced by VPF\\/VEGF, we injected an adenoviral vector engineered to express murine VPF\\/VEGF164 into several normal tissues of adult nude mice or rats. A dose-dependent angiogenic response was induced in all tissues

Anna Pettersson; Janice A Nagy; Lawrence F Brown; Christian Sundberg; Ellen Morgan; Steven Jungles; Robert Carter; Jose E Krieger; Eleanor J Manseau; V Susan Harvey; Isabelle A Eckelhoefer; Dian Feng; Ann M Dvorak; Richard C Mulligan; Harold F Dvorak

2000-01-01

32

Twist1 controls lung vascular permeability and endotoxin-induced pulmonary edema by altering Tie2 expression.  

PubMed

Tight regulation of vascular permeability is necessary for normal development and deregulated vascular barrier function contributes to the pathogenesis of various diseases, including acute respiratory distress syndrome, cancer and inflammation. The angiopoietin (Ang)-Tie2 pathway is known to control vascular permeability. However, the mechanism by which the expression of Tie2 is regulated to control vascular permeability has not been fully elucidated. Here we show that transcription factor Twist1 modulates pulmonary vascular leakage by altering the expression of Tie2 in a context-dependent way. Twist1 knockdown in cultured human lung microvascular endothelial cells decreases Tie2 expression and phosphorylation and increases RhoA activity, which disrupts cell-cell junctional integrity and increases vascular permeability in vitro. In physiological conditions, where Ang1 is dominant, pulmonary vascular permeability is elevated in the Tie2-specific Twist1 knockout mice. However, depletion of Twist1 and resultant suppression of Tie2 expression prevent increase in vascular permeability in an endotoxin-induced lung injury model, where the balance of Angs shifts toward Ang2. These results suggest that Twist1-Tie2-Angs signaling is important for controlling vascular permeability and modulation of this mechanism may lead to the development of new therapeutic approaches for pulmonary edema and other diseases caused by abnormal vascular permeability. PMID:24023872

Mammoto, Tadanori; Jiang, Elisabeth; Jiang, Amanda; Lu, Yongbo; Juan, Aimee M; Chen, Jing; Mammoto, Akiko

2013-01-01

33

Suppressions of serotonin-induced increased vascular permeability and leukocyte infiltration by Bixa orellana leaf extract.  

PubMed

The aim of the present study was to evaluate the anti-inflammatory activities of aqueous extract of Bixa orellana (AEBO) leaves and its possible mechanisms in animal models. The anti-inflammatory activity of the extract was evaluated using serotonin-induced rat paw edema, increased peritoneal vascular permeability, and leukocyte infiltrations in an air-pouch model. Nitric oxide (NO), indicated by the sum of nitrites and nitrates, and vascular growth endothelial growth factor (VEGF) were measured in paw tissues of rats to determine their involvement in the regulation of increased permeability. Pretreatments with AEBO (50 and 150?mg?kg?¹) prior to serotonin inductions resulted in maximum inhibitions of 56.2% of paw volume, 45.7% of Evans blue dye leakage in the peritoneal vascular permeability model, and 83.9% of leukocyte infiltration in the air-pouch model. 57.2% maximum inhibition of NO and 27% of VEGF formations in rats' paws were observed with AEBO at the dose of 150?mg?kg?¹. Pharmacological screening of the extract showed significant (P < 0.05) anti-inflammatory activity, indicated by the suppressions of increased vascular permeability and leukocyte infiltration. The inhibitions of these inflammatory events are probably mediated via inhibition of NO and VEGF formation and release. PMID:24224164

Yong, Yoke Keong; Sulaiman, NurShahira; Hakim, Muhammad Nazrul; Lian, Gwendoline Ee Cheng; Zakaria, Zainul Amirudin; Othman, Fauziah; Ahmad, Zuraini

2013-01-01

34

Suppressions of Serotonin-Induced Increased Vascular Permeability and Leukocyte Infiltration by Bixa orellana Leaf Extract  

PubMed Central

The aim of the present study was to evaluate the anti-inflammatory activities of aqueous extract of Bixa orellana (AEBO) leaves and its possible mechanisms in animal models. The anti-inflammatory activity of the extract was evaluated using serotonin-induced rat paw edema, increased peritoneal vascular permeability, and leukocyte infiltrations in an air-pouch model. Nitric oxide (NO), indicated by the sum of nitrites and nitrates, and vascular growth endothelial growth factor (VEGF) were measured in paw tissues of rats to determine their involvement in the regulation of increased permeability. Pretreatments with AEBO (50 and 150?mg?kg?1) prior to serotonin inductions resulted in maximum inhibitions of 56.2% of paw volume, 45.7% of Evans blue dye leakage in the peritoneal vascular permeability model, and 83.9% of leukocyte infiltration in the air-pouch model. 57.2% maximum inhibition of NO and 27% of VEGF formations in rats' paws were observed with AEBO at the dose of 150?mg?kg?1. Pharmacological screening of the extract showed significant (P < 0.05) anti-inflammatory activity, indicated by the suppressions of increased vascular permeability and leukocyte infiltration. The inhibitions of these inflammatory events are probably mediated via inhibition of NO and VEGF formation and release. PMID:24224164

Sulaiman, NurShahira; Hakim, Muhammad Nazrul; Lian, Gwendoline Ee Cheng; Zakaria, Zainul Amirudin; Othman, Fauziah; Ahmad, Zuraini

2013-01-01

35

Vascular permeability enhancement in solid tumor: various factors, mechanisms involved and its implications.  

PubMed

Most solid tumors are known to exhibit highly enhanced vascular permeability, similar to or more than the inflammatory tissues. Common denominators affecting both cancer and inflammatory lesions are now well known: bradykinin (BK), nitric oxide (NO), peroxynitrite (ONOO(-)), prostaglandins (PGs), collagenases or matrix metalloproteinases (MMPs) and others. Incidentally, enzymes involved in these mediator syntheses are upregulated or activated. Initially described vascular permeability factor (VPF) (proteinaceous) was later identified to be the same as vascular endothelial growth factor (VEGF), which promotes angiogenesis of cancer tissues as well. These mediators cross-talk or co-upregulate each other, such as BK-NO-PGs system. Therefore, vascular permeability observed in solid tumor may reflect the other side of the coin (angiogenesis). The vascular permeability and accumulation of plasma components in the interstitium described here is applicable for predominantly macromolecules (molecular weight, Mw>45 kDa), but not for low molecular compounds as most anticancer agents are. Macromolecular compounds (e.g., albumin, transferrin) or many biocompatible water-soluble polymers show this effect. Furthermore, they are not cleared rapidly from the sites of lesion (cancer/inflammatory tissue), thus, remain for prolonged time, usually for more than a few days. This phenomenon of "enhanced permeability and retention effect" observed in cancer tissue for macromolecules and lipids is coined "EPR effect", which is now widely accepted as a gold standard for anticancer drug designing to seek more cancer-selective targeting using macromolecular drugs. Consequently, drastic reduction of the systemic side effect is observed, while the macromolecular drugs will continuously exert antitumor activity. Other advantages of macromolecular drugs are also discussed. PMID:12639809

Maeda, Hiroshi; Fang, Jun; Inutsuka, Takao; Kitamoto, Yasunori

2003-03-01

36

Different vascular permeability between the sensory and secretory circumventricular organs of adult mouse brain.  

PubMed

The blood-brain barrier (BBB) prevents free access of circulating molecules to the brain and maintains a specialized brain environment to protect the brain from blood-derived bioactive and toxic molecules; however, the circumventricular organs (CVOs) have fenestrated vasculature. The fenestrated vasculature in the sensory CVOs, including the organum vasculosum of lamina terminalis (OVLT), subfornical organ (SFO) and area postrema (AP), allows neurons and astrocytes to sense a variety of plasma molecules and convey their information into other brain regions and the vasculature in the secretory CVOs, including median eminence (ME) and neurohypophysis (NH), permits neuronal terminals to secrete many peptides into the blood stream. The present study showed that vascular permeability of low-molecular-mass tracers such as fluorescein isothiocyanate (FITC) and Evans Blue was higher in the secretory CVOs and kidney as compared with that in the sensory CVOs. On the other hand, vascular permeability of high-molecular-mass tracers such as FITC-labeled bovine serum albumin and Dextran 70,000 was lower in the CVOs as compared with that in the kidney. Prominent vascular permeability of low- and high-molecular-mass tracers was also observed in the arcuate nucleus. These data demonstrate that vascular permeability for low-molecular-mass molecules is higher in the secretory CVOs as compared with that in the sensory CVOs, possibly for large secretion of peptides to the blood stream. Moreover, vascular permeability for high-molecular-mass tracers in the CVOs is smaller than that of the kidney, indicating that the CVOs are not totally without a BBB. PMID:22584508

Morita, Shoko; Miyata, Seiji

2012-08-01

37

The effect of ASK1 on vascular permeability and edema formation in cerebral ischemia.  

PubMed

Apoptosis signal-regulating kinase-1 (ASK1) is the mitogen-activated protein kinase kinase kinase (MAPKKK) and participates in the various central nervous system (CNS) signaling pathways. In cerebral ischemia, vascular permeability in the brain is an important issue because regulation failure of it results in edema formation and blood-brain barrier (BBB) disruption. To determine the role of ASK1 on vascular permeability and edema formation following cerebral ischemia, we first investigated ASK1-related gene expression using microarray analyses of ischemic brain tissue. We then measured protein levels of ASK1 and vascular endothelial growth factor (VEGF) in brain endothelial cells after hypoxia injury. We also examined protein expression of ASK1 and VEGF, edema formation, and morphological alteration through cresyl violet staining in ischemic brain tissue using ASK1-small interference RNA (ASK1-siRNA). Finally, immunohistochemistry was performed to examine VEGF and aquaporin-1 (AQP-1) expression in ischemic brain injury. Based on our findings, we propose that ASK1 is a regulating factor of vascular permeability and edema formation in cerebral ischemia. PMID:25446452

Song, Juhyun; Cheon, So Yeong; Lee, Won Taek; Park, Kyung Ah; Lee, Jong Eun

2015-01-21

38

Phosphorylation of VE-cadherin is modulated by haemodynamic forces and contributes to the regulation of vascular permeability in vivo  

PubMed Central

Endothelial adherens junctions maintain vascular integrity. Arteries and veins differ in their permeability but whether organization and strength of their adherens junctions vary has not been demonstrated in vivo. Here we report that vascular endothelial cadherin, an endothelial specific adhesion protein located at adherens junctions, is phosphorylated in Y658 and Y685 in vivo in veins but not in arteries under resting conditions. This difference is due to shear stress-induced junctional Src activation in veins. Phosphorylated vascular endothelial-cadherin is internalized and ubiquitinated in response to permeability-increasing agents such as bradykinin and histamine. Inhibition of Src blocks vascular endothelial cadherin phosphorylation and bradykinin-induced permeability. Point mutation of Y658F and Y685F prevents vascular endothelial cadherin internalization, ubiquitination and an increase in permeability by bradykinin in vitro. Thus, phosphorylation of vascular endothelial cadherin contributes to a dynamic state of adherens junctions, but is not sufficient to increase vascular permeability in the absence of inflammatory agents. PMID:23169049

Orsenigo, Fabrizio; Giampietro, Costanza; Ferrari, Aldo; Corada, Monica; Galaup, Ariane; Sigismund, Sara; Ristagno, Giuseppe; Maddaluno, Luigi; Young Koh, Gou; Franco, Davide; Kurtcuoglu, Vartan; Poulikakos, Dimos; Baluk, Peter; McDonald, Donald; Grazia Lampugnani, Maria; Dejana, Elisabetta

2012-01-01

39

Propofol-induced vascular permeability change is related to the nitric oxide signaling pathway and occludin phosphorylation.  

PubMed

The present study was undertaken to elucidate the mechanism of intra-arterial propofol-induced vascular permeability change resulting in tissue edema. The mechanism of propofol-induced hyperpermeability was examined in a rat femoral artery injection model. Vascular permeability was determined by measuring the Evans blue content of the dorsal skin of the infused limb at 15, 30, 45 and 60 min after propofol injection. The total content of the tight junction proteins occludin, ZO-1 and claudin-5 under experimental conditions was also determined by western blotting. Intra-arterial injection with propofol resulted in a marked dose-dependent increase in vascular permeability of the rat hindpaw. Pretreatment with 10 mg/kg of N-nitro-L: -arginine methyl ester (L: -NAME) but not aminoguanidine significantly inhibited the change in vascular permeability after challenge with propofol. Pretreatment with L: -arginine and nitroprusside increased the propofol-induced permeability change. Intra-arterial injection of propofol significantly increased occludin phosphorylation after 15 min, which was consistent with the time profile of the vascular permeability change. L: -NAME partially reversed the change in occludin phosphorylation, whereas aminoguanidine had no effect compared with that in the controls. Our observations indicate that nitric oxide (NO) is an important mediator in the induction of vascular permeability induced by propofol. Occludin phosphorylation is a determining factor in the vascular permeability change induced by propofol. NO synthase (NOS) inhibitors might be useful in the treatment of accidental intra-arterial injection of propofol, in the reduction of any adverse effects. PMID:17394100

Chen, Yi-Shen; Chen, Kuan-Hung; Liu, Chien-Cheug; Lee, Chien-Te; Yang, Chien-Hui; Chuang, Kuan-Chih; Lin, Chung-Ren

2007-09-01

40

Effects of Extremely Low Frequency Electromagnetic Fields on Vascular Permeability of Circumventricular Organs in the Adult Rat  

NASA Astrophysics Data System (ADS)

The present work deals with the effects of extremely low frequency electromagnetic fields (ELF-EMF) on blood vessels permeability to non liposoluble substances of the circumventricular organs (CVO) of adult rats. Male Wistar adult rats were exposed to ELF-EMF and vascular permeability to colloidal carbon was investigated with the use of histological techniques. Results were compared to corresponding data from sham-exposed and control groups of animals. Exposure to ELF-EMF increased the CVO vascular permeability to colloidal carbon intravascularly injected, particularly in the subfornical organ, the median eminence, the pineal gland and the area postrema.

Gutiérrez-Mercado, Y. K.; Cañedo-Dorantes, L.; Bañuelos-Pineda, J.; Serrano-Luna, G.; Feria-Velasco, A.

2008-08-01

41

Cortactin deficiency is associated with reduced neutrophil recruitment but increased vascular permeability in vivo  

PubMed Central

Neutrophil extravasation and the regulation of vascular permeability require dynamic actin rearrangements in the endothelium. In this study, we analyzed in vivo whether these processes require the function of the actin nucleation–promoting factor cortactin. Basal vascular permeability for high molecular weight substances was enhanced in cortactin-deficient mice. Despite this leakiness, neutrophil extravasation in the tumor necrosis factor–stimulated cremaster was inhibited by the loss of cortactin. The permeability defect was caused by reduced levels of activated Rap1 (Ras-related protein 1) in endothelial cells and could be rescued by activating Rap1 via the guanosine triphosphatase (GTPase) exchange factor EPAC (exchange protein directly activated by cAMP). The defect in neutrophil extravasation was caused by enhanced rolling velocity and reduced adhesion in postcapillary venules. Impaired rolling interactions were linked to contributions of ?2-integrin ligands, and firm adhesion was compromised by reduced ICAM-1 (intercellular adhesion molecule 1) clustering around neutrophils. A signaling process known to be critical for the formation of ICAM-1–enriched contact areas and for transendothelial migration, the ICAM-1–mediated activation of the GTPase RhoG was blocked in cortactin-deficient endothelial cells. Our results represent the first physiological evidence that cortactin is crucial for orchestrating the molecular events leading to proper endothelial barrier function and leukocyte recruitment in vivo. PMID:21788407

Schnoor, Michael; Lai, Frank P.L.; Zarbock, Alexander; Kläver, Ruth; Polaschegg, Christian; Schulte, Dörte; Weich, Herbert A.; Oelkers, J. Margit; Rottner, Klemens

2011-01-01

42

Changes in Vascular Permeability and Expression of Different Angiogenic Factors Following Anti-Angiogenic Treatment in Rat Glioma  

Microsoft Academic Search

BackgroundAnti-angiogenic treatments of malignant tumors targeting vascular endothelial growth factor receptors (VEGFR) tyrosine kinase are being used in different early stages of clinical trials. Very recently, VEGFR tyrosine kinase inhibitor (Vetanalib, PTK787) was used in glioma patient in conjunction with chemotherapy and radiotherapy. However, changes in the tumor size, tumor vascular permeability, vascular density, expression of VEGFR2 and other angiogenic

Meser M. Ali; Branislava Janic; Abbas Babajani-Feremi; Nadimpalli R. S. Varma; A. S. M. Iskander; John Anagli; Ali S. Arbab; Andrew Boswell

2010-01-01

43

Vascular Endothelial Growth Factors Enhance the Permeability of the Mouse Blood-brain Barrier  

PubMed Central

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

44

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

45

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.; Carrière, Catherine

2012-01-01

46

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

47

Continuous arterio-venous haemodiafiltration: hydraulic and diffusive permeability index of an AN-69 capillary haemofilter.  

PubMed

The dependence of uraemic solute clearance on the hydraulic and diffusive permeability index of an AN-69 capillary haemofilter is investigated during the treatment of patients with continuous arterio-venous haemodiafiltration (CAVHD). A mathematical model is presented to calculate solute clearance and the hydraulic and diffusive permeability index parameters from clinical data and to predict the blood flow rate entering the extra-corporeal circuit from the manufacturer's specifications and blood viscosity. By measuring the flow rates, the patient's mean arterio-venous pressure difference and uraemic solute clearance under different clinical and operational conditions, mathematical model equations are evaluated. During the average survival time of an AN-69 capillary haemofilter of about five days, it is found that both the hydraulic permeability index and the diffusive permeability index decline over treatment time, independent of the haemofilter resistance to blood flow. The measured haemofilter resistance to blood flow is three times higher than the haemofilter resistance predicted from the manufacturer's specifications and blood viscosity. Predicting the blood flow rate entering the extra-corporeal circuit from the arterial haematocrit, plasma protein concentration and temperature and the manufacturer's specifications is not reliable. PMID:9614747

Akcahuseyin, E; van Duyl, W A; Vincent, H H; Vos, M C; Schalekamp, M A

1998-01-01

48

Phosphoramidon blocks big-endothelin-1 but not endothelin-1 enhancement of vascular permeability in the rat.  

PubMed Central

1. Changes in vascular permeability following intravenous injections of human big-endothelin-1 (big-ET-1) and endothelin-1 (ET-1) were measured by extravasation of Evans blue dye (EB, 20 mg kg-1) in selected tissues. 2. A low dose of big-ET-1 (40 pmol kg-1) failed to alter vascular permeability but a dose of 400 pmol kg-1 increased EB extravasation in the trachea, upper and lower bronchi, and lung parenchyma by 55 to 69% (P < 0.05). Vascular permeability was also enhanced in the liver, spleen, kidney, heart, and diaphragm by 20, 14, 41, 25, and 67%, respectively (P < 0.05). 3. Upon injection of ET-1 (400 pmol kg-1), EB extravasation increased in the upper and lower bronchi, lung parenchyma, liver, pancreas, kidney, heart, and diaphragm. 4. Administration of ET-1 and big-ET-1 was not associated with significant systemic responses. 5. Pretreatment with phosphoramidon (PA) blocked the response to big-ET-1 in all tissues examined but this inhibitor failed to alter the response to ET-1. 6. We conclude from these results that the dose-dependent increase in vascular permeability induced by big-ET-1 in various tissues follows its conversion to ET-1 by the endothelin converting enzyme, a PA-sensitive process. PMID:1467845

Lehoux, S.; Plante, G. E.; Sirois, M. G.; Sirois, P.; D'Orléans-Juste, P.

1992-01-01

49

Role of nitric oxide in tumor microcirculation. Blood flow, vascular permeability, and leukocyte-endothelial interactions.  

PubMed Central

The present study was designed to define the role of nitric oxide (NO) in tumor microcirculation, through the direct intravital microcirculatory observations after administration of NO synthase (NOS) inhibitor and NO donor both regionally and systemically. More specifically, we tested the following hypotheses: 1) endogenous NO derived from tumor vascular endothelium and/or tumor cells increases and/or maintains tumor blood flow, decreases leukocyte-endothelial interactions, and increases vascular permeability, 2) exogenous NO can increase tumor blood flow via vessel dilatation and decrease leukocyte-endothelial interactions, and 3) NO production and tissue responses to NO are tumor dependent. To this end, a murine mammary adenocarcinoma (MCaIV) and a human colon adenocarcinoma (LS174T) were implanted in the dorsal skinfold chamber in C3H and severe combined immunodeficient mice, respectively, and observed by means of intravital fluorescence microscopy. Both regional and systemic inhibition of endogenous NO by N omega-nitro-L-arginine methyl ester (L-NAME; 100 mumol/L superfusion or 10 mg/kg intravenously) significantly decreased vessel diameter and local blood flow rate. The diameter change was dominant on the arteriolar side. Superfusion of NO donor (spermine NO, 100 mumol/L) increased tumor vessel diameter and flow rate, whereas systemic injection of spermine NO (2.62 mg/kg) had no significant effect on these parameters. Rolling and stable adhesion of leukocytes were significantly increased by intravenous injection of L-NAME. In untreated animals, both MCaIV and LS174T tumor vessels were leaky to albumin. Systemic NO inhibition significantly attenuated tumor vascular permeability of MCaIV but not of LS174T tumor. Immunohistochemical studies, using polyclonal antibodies to endothelial NOS and inducible NOS, revealed a diffuse pattern of positive labeling in both MCaIV and LS174T tumors. Nitrite and nitrate levels in tumor interstitial fluid of MCaIV but not of LS174T were significantly higher than that in normal subcutaneous interstitial fluid. These results support our hypotheses regarding the microcirculatory response to NO in tumors. Modulation of NO level in tumors is a potential strategy for altering tumor hemodynamics and thus improving oxygen, drug, gene vector, and effector cell delivery to solid tumors. Images Figure 5 PMID:9033284

Fukumura, D.; Yuan, F.; Endo, M.; Jain, R. K.

1997-01-01

50

A Role for a CXCR2/Phosphatidylinositol 3-Kinase ? Signaling Axis in Acute and Chronic Vascular Permeability? †  

PubMed Central

Most proangiogenic polypeptide growth factors and chemokines enhance vascular permeability, including vascular endothelial growth factor (VEGF), the main target for anti-angiogenic-based therapies, and interleukin-8 (IL-8), a potent proinflammatory mediator. Here, we show that in endothelial cells IL-8 initiates a signaling route that converges with that deployed by VEGF at the level of the small GTPase Rac1 and that both act through the p21-activated kinase to promote the phosphorylation and internalization of VE-cadherin. However, whereas VEGF activates Rac1 through Src-related kinases, IL-8 specifically signals to Rac1 through its cognate G protein-linked receptor, CXCR2, and the stimulation of the phosphatidylinositol 3-kinase ? (PI3K?) catalytic isoform, thereby providing a specific molecular targeted intervention in vascular permeability. These results prompted us to investigate the potential role of IL-8 signaling in a mouse model for retinal vascular hyperpermeability. Importantly, we observed that IL-8 is upregulated upon laser-induced retinal damage, which recapitulates enhanced vascularization, leakage, and inflammatory responses. Moreover, blockade of CXCR2 and PI3K? was able to limit neovascularization and choroidal edema, as well as macrophage infiltration, therefore contributing to reduce retinal damage. These findings indicate that the CXCR2 and PI3K? signaling pathway may represent a suitable target for the development of novel therapeutic strategies for human diseases characterized by vascular leakage. PMID:19255141

Gavard, Julie; Hou, Xu; Qu, Yi; Masedunskas, Andrius; Martin, Daniel; Weigert, Roberto; Li, Xuri; Gutkind, J. Silvio

2009-01-01

51

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

52

VEGFR2 induces c-Src signaling and vascular permeability in vivo via the adaptor protein TSAd  

PubMed Central

Regulation of vascular endothelial (VE) growth factor (VEGF)–induced permeability is critical in physiological and pathological processes. We show that tyrosine phosphorylation of VEGF receptor 2 (VEGFR2) at Y951 facilitates binding of VEGFR2 to the Rous sarcoma (Src) homology 2-domain of T cell–specific adaptor (TSAd), which in turn regulates VEGF-induced activation of the c-Src tyrosine kinase and vascular permeability. c-Src was activated in vivo and in vitro in a VEGF/TSAd-dependent manner, and was regulated via increased phosphorylation at pY418 and reduced phosphorylation at pY527. Tsad silencing blocked VEGF-induced c-Src activation, but did not affect pathways involving phospholipase C?, extracellular regulated kinase, and endothelial nitric oxide. VEGF-induced rearrangement of VE–cadherin–positive junctions in endothelial cells isolated from mouse lungs, or in mouse cremaster vessels, was dependent on TSAd expression, and TSAd formed a complex with VE-cadherin, VEGFR2, and c-Src at endothelial junctions. Vessels in tsad?/? mice showed undisturbed flow and pressure, but impaired VEGF-induced permeability, as measured by extravasation of Evans blue, dextran, and microspheres in the skin and the trachea. Histamine-induced extravasation was not affected by TSAd deficiency. We conclude that TSAd is required for VEGF-induced, c-Src-mediated regulation of endothelial cell junctions and for vascular permeability. PMID:22689825

Sun, Zuyue; Li, Xiujuan; Massena, Sara; Kutschera, Simone; Padhan, Narendra; Gualandi, Laura; Sundvold-Gjerstad, Vibeke; Gustafsson, Karin; Choy, Wing Wen; Zang, Guangxiang; Quach, My; Jansson, Leif; Phillipson, Mia; Abid, Md Ruhul; Spurkland, Anne

2012-01-01

53

Differentiation between vascular permeability factor and IL-2 in lymphocyte supernatants from patients with minimal-change nephrotic syndrome.  

PubMed Central

Immunotherapy of cancers with recombinant IL-2 induces a vascular leak syndrome which is mainly due to an increase in vascular permeability. A lymphokine, the vascular permeability factor (VPF), which increases vascular permeability, has been characterized in minimal-change nephrotic syndrome (MCNS) and appeared very similar to IL-2. Here we have undertaken a further characterization of VPF in order to determine how closely related this factor was to human IL-2. Both the IL-2 bioassay and Western blot analysis of the MCNS lymphocyte concentrated supernatants with high VPF activity revealed the presence of low quantities of IL-2. Preparative isoelectrofocusing (IEF) of concentrated supernatants resolved each lymphokine in a separate peak, with apparent pIs of 5.2 for VPF and 7.5-10.1 for IL-2. Since a sensitive IL-2 ELISA failed to exhibit any significant antigenic presence of IL-2 in the IEF fractions with the highest VPF activity, we conclude that VPF activity of the concentrated supernatants is not related to IL-2 nor to a biologically inactive form of IL-2. When concentrated supernatants were subjected to preparative SDS-PAGE, VPF activity was recovered within low mol. wt material (1-12 kD). Immunoadsorption experiments gave definite proof since the complete removal of IL-2 from concentrated supernatants did not affect the VPF activity. Although high amounts of IL-2 increased vascular permeability, our experiments clearly demonstrate that VPF is a lymphokine distinct from IL-2. Images Fig. 1 Fig. 3 Fig. 4 PMID:1914229

Heslan, J M; Branellec, A I; Pilatte, Y; Lang, P; Lagrue, G

1991-01-01

54

Vascular permeability and axonal regeneration in skin autotransplanted into the brain.  

PubMed Central

Pieces of skin were autotransplanted from the pinna of an ear into a cerebral hemisphere in 36 albino rats. The grafts were examined 2, 4 and 6 weeks later for signs of vascular permeability and for the presence of nerve fibres. An intravenously injected fluorescent protein exuded into the connective tissue of the dermis and into the spaces between epidermal cells. Extravascular leukocytes were also seen in the dermis. Nerve fibres, derived from the caudate nucleus, corpus callosum and neocortex, were seen in nearly all the grafts, entering both the dermis and epidermis. They were more numerous after the fourth and sixth than after the second post-operative week. A few of these axons were myelinated and a few contained acetylcholinesterase. It has thus been shown that central axons can regenerate into a region in which they are surrounded by proteins and cells derived from the blood, for at least 6 weeks. This observation does not support a recently advanced hypothesis invoking autoimmunity as the cause of the failure of most axons to regenerate following severance within the central nervous system. It is tentatively suggested that the presence of plasma proteins in the extracellular fluid around the tips of axons may be necessary for the occurrence of regeneration. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 PMID:342472

Heinicke, E A; Kiernan, J A

1978-01-01

55

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

56

Mast cells increase vascular permeability by heparin-initiated bradykinin formation in vivo.  

PubMed

Activated mast cells trigger edema in allergic and inflammatory disease. We report a paracrine mechanism by which mast cell-released heparin increases vascular permeability in vivo. Heparin activated the protease factor XII, which initiates bradykinin formation in plasma. Targeting factor XII or kinin B2 receptors abolished heparin-triggered leukocyte-endothelium adhesion and interfered with a mast cell-driven drop in blood pressure in rodents. Intravital laser scanning microscopy and tracer measurements showed heparin-driven fluid extravasation in mouse skin microvessels. Ablation of factor XII or kinin B2 receptors abolished heparin-induced skin edema and protected mice from allergen-activated mast cell-driven leakage. In contrast, heparin and activated mast cells induced excessive edema in mice deficient in the major inhibitor of factor XII, C1 esterase inhibitor. Allergen exposure triggered edema attacks in hereditary angioedema patients, lacking C1 esterase inhibitor. The data indicate that heparin-initiated bradykinin formation plays a fundamental role in mast cell-mediated diseases. PMID:21349432

Oschatz, Chris; Maas, Coen; Lecher, Bernd; Jansen, Thomas; Björkqvist, Jenny; Tradler, Thomas; Sedlmeier, Reinhard; Burfeind, Peter; Cichon, Sven; Hammerschmidt, Sven; Müller-Esterl, Werner; Wuillemin, Walter A; Nilsson, Gunnar; Renné, Thomas

2011-02-25

57

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

58

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

59

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.

60

Role of histamine in aggravation of gastric acid back-diffusion and vascular permeability in septic rats.  

PubMed

The aim of the present study was to investigate the role of histamine in aggravation of gastric acid back-diffusion and vascular permeability in lipopolysaccharide (LPS)-induced septic rats. Male specific pyrogen-free Wistar rats were deprived food for 24 h before the experiment. Intravenous LPS (3 mg/kg dissolved in sterilized saline) was given to rats 12 h after food removal. Control rats received sterilized saline only. Under diethylether-anesthesia, the pylorus and esophageal sphincters of rats were ligated. Vagotomy also was performed. The stomachs were then irrigated for 3 h with physiological acid solutions containing 0-150 mM HCl plus adequate amount of NaCl. Increases in various ulcerogenic parameters, such as gastric acid back-diffusion, mucosal histamine concentration, luminal hemoglobin (Hb) content and stomach ulcer, were dependent on the concentration of acid solutions irrigated in stomachs of those LPS rats. Gastric vascular permeability also was increased in an acid concentration-related manner. In those LPS rats, high correlation was found between extents of acid back-diffusion and mucosal ulceration. Increased vascular permeability also closely related to the luminal Hb content. Moreover, these ulcerogenic parameters were dose-dependently ameliorated by intraperitoneal ketotifen and ranitidine. Diamine oxidase also was effective in inhibition, but exogenous histamine on the contrary, produced exacerbation of these ulcerogenic parameters. In conclusion, histamine plays a pivotal role in modulating gastric acid back-diffusion and vascular permeability that are greatly associated with hemorrhagic ulcer in septic rats. PMID:11908549

Hung, C R

2001-12-31

61

Silver nanoparticles inhibit VEGF-and IL-1?-induced vascular permeability via Src dependent pathway in porcine retinal endothelial cells  

PubMed Central

The aim of this study is to determine the effects of silver nanoparticles (Ag-NP) on vascular endothelial growth factor (VEGF)-and interleukin-1 beta (IL-1?)-induced vascular permeability, and to detect the underlying signaling mechanisms involved in endothelial cells. Porcine retinal endothelial cells (PRECs) were exposed to VEGF, IL-1? and Ag-NP at different combinations and endothelial cell permeability was analyzed by measuring the flux of RITC-dextran across the PRECs monolayer. We found that VEGF and IL-1? increase flux of dextran across a PRECs monolayer, and Ag-NP block solute flux induced by both VEGF and IL-1?. To explore the signalling pathway involved VEGF- and IL-1?-induced endothelial alteration, PRECs were treated with Src inhibitor PP2 prior to VEGF and IL-1? treatment, and the effects were recorded. Further, to clarify the possible involvement of the Src pathways in endothelial cell permeability, plasmid encoding dominant negative(DN) and constitutively active(CA) form of Src kinases were transfected into PRECs, 24 h prior to VEGF and IL-1? exposure and the effects were recorded. Overexpression of DN Src blocked both VEGF-and IL-1?-induced permeability, while overexpression of CA Src rescues the inhibitory action of Ag-NP in the presence or absence of VEGF and IL-1?. Further, an in vitro kinase assay was performed to identify the presence of the Src phosphorylation at Y419. We report that VEGF and IL-1?-stimulate endothelial permeability via Src dependent pathway by increasing the Src phosphorylation and Ag-NP block the VEGF-and IL-1?-induced Src phosphorylation at Y419. These results demonstrate that Ag-NP may inhibit the VEGF-and IL-1?-induced permeability through inactivation of Src kinase pathway and this pathway may represent a potential therapeutic target to inhibit the ocular diseases such as diabetic retinopathy. PMID:19878566

Sheikpranbabu, Sardarpasha; Kalishwaralal, Kalimuthu; Venkataraman, Deepak; Eom, Soo Hyun; Park, Jongsun; Gurunathan, Sangiliyandi

2009-01-01

62

Effect of mini-tyrosyl-tRNA synthetase on ischemic angiogenesis, leukocyte recruitment, and vascular permeability.  

PubMed

Mini-tyrosyl-tRNA synthetase (mini-TyrRS), the N-terminal domain of tyrosyl-tRNA synthetase, is a recently identified protein released by endothelial cells that exhibits angiogenic and leukocyte chemoattractant, ELR-motif (Glu-Leu-Arg)-dependent activities in vitro. We sought to determine whether exogenous mini-TyrRS exerts these and other cytokine-like actions in physiological and pathological settings in vivo. High-dose mini-TyrRS (600 microg.kg(-1).day(-1)) augmented while low-dose mini-TyrRS (3 microg.kg(-1).day(-1)), unexpectedly, inhibited angiogenesis in the ischemic mouse ear. Enhanced angiogenesis was associated with increased CD45- and CD4-positive leukocyte accumulation. Mini-TyrRS also had biphasic actions on both basal and mustard oil-evoked and VEGF-evoked leakage of Evan's blue dye-albumin in nonischemic ear and in endothelial cell monolayers, that is, low-dose inhibited and high-dose augmented leakage. Mutation of the ELR motif of mini-TyrRS abolished the above activities. Mini-TyrRS was reduced (immunoblot) in extracts of ischemic calf muscle and in thoracic aorta explants exposed to hypoxia or VEGF. Inhibition of VEGF with a soluble Flt1 "trap" protein abolished this hypoxic-induced reduction in mini-TyrRS in aorta explants. These data show that mini-TyrRS has dose-dependent biphasic effects on ischemic angiogenesis and vascular permeability in vivo, that is, antiangiogenic and antipermeability activities at low concentration and proangiogenic, propermeability activities at high concentrations. PMID:18753262

Cheng, Gang; Zhang, Hua; Yang, Xianglei; Tzima, Eleni; Ewalt, Karla L; Schimmel, Paul; Faber, James E

2008-10-01

63

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

64

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

E-print Network

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 risks of death and dementia in relation to vascular risk factors the Gothenburg H-70 1901-02 birth

Mitnitski, Arnold B.

65

Antagonism of VEGF-A–induced increase in vascular permeability by an integrin ?3?1-Shp-1-cAMP/PKA pathway  

PubMed Central

In cancer, VEGF-induced increase in vascular permeability results in increased interstitial pressure, reducing perfusion and increasing hypoxia, which reduce delivery of chemotherapeutic agents and increase resistance to ionizing radiation. Here, we show that both TIMP-2 and Ala + TIMP-2, a TIMP-2 mutant without matrix metalloproteinase inhibitory activity, antagonize the VEGF-A–induced increase in vascular permeability, both in vitro and in vivo. Like other agents known to preserve endothelial barrier function, TIMP-2 elevates cytosolic levels of cAMP and increases cytoskeletal-associated vascular endothelial cadherin in human microvascular endothelial cells. All of these effects are completely ablated by selective knockdown of integrin ?3?1 expression, expression of a dominant negative protein tyrosine phosphatase Shp-1 mutant, administration of the protein tyrosine phosphatase inhibitor orthovanadate, or the adenylate cyclase inhibitor SQ22536. This TIMP-2–mediated inhibition of vascular permeability involves an integrin ?3?1-Shp-1-cAMP/protein kinase A-dependent vascular endothelial cadherin cytoskeletal association, as evidenced by using siRNAs to integrin ?3?1 and Shp-1, or treatment with Shp-1 inhibitor NSC87877 and protein kinase A inhibitor H89. Our results demonstrate the potential utility for TIMP-2 in cancer therapy through “normalization” of vascular permeability in addition to previously described antiangiogenic effects. PMID:23074279

Kim, Soo Hyeon; Cho, Young-Rak; Kim, Hyeon-Ju; Oh, Joa Sub; Ahn, Eun-Kyung; Ko, Hye-Jin; Hwang, Byung Joon; Lee, Seo-Jin; Cho, Yongwan; Kim, Yong Kee

2012-01-01

66

Enhanced dermal and retinal vascular permeability in streptozotocin-induced type 1 diabetes in Wistar rats: blockade with a selective bradykinin B1 receptor antagonist.  

PubMed

The vascular complications associated with type 1 diabetes are to some extent related to the dysfunction of the endothelium leading to an increased vascular permeability and plasma extravasation in the surrounding tissues. The various micro- and macro-vascular complications of diabetes develop over time, leading to nephropathy, retinopathy and neuropathy and cardiomyopathy. In the present study, the effect of a novel selective bradykinin B1 receptor (BKB1-R) antagonist, R-954, was investigated on the changes of vascular permeability in the skin and retina of streptozotocin (STZ)-induced type 1 diabetic rats. Plasma extravasation increased in the skin and retina of STZ-diabetic rats after 1 week and persisted over 4 weeks following STZ injection. Acute treatment with R-954 (2 mg/kg, bolus s.c.) highly reduced the elevated vascular permeability in both 1- and 4-week STZ-diabetic rats. These results showed that the inducible BKB1-R subtype modulates the vascular permeability of the skin and retina of type 1 diabetic rats and suggests that BKB1-R antagonists could have a beneficial role in diabetic neuropathy and retinopathy. PMID:15544863

Lawson, Sibi R; Gabra, Bichoy H; Guérin, Brigitte; Neugebauer, Witold; Nantel, François; Battistini, Bruno; Sirois, Pierre

2005-01-15

67

Angiomodulin, a marker of cancer vasculature, is upregulated by vascular endothelial growth factor and increases vascular permeability as a ligand of integrin ?v?3  

PubMed Central

Angiomodulin (AGM) is a member of insulin-like growth factor binding protein (IGFBP) superfamily and often called IGFBP-rP1 or IGFBP-7. AGM was originally identified as a tumor-derived cell adhesion factor, which was highly accumulated in blood vessels of human cancer tissues. AGM is also overexpressed in cancer-associated fibroblasts (CAFs) and activates fibroblasts. However, some studies have shown tumor-suppressing activity of AGM. To understand the roles of AGM in cancer progression, we here investigated the expression of AGM in benign and invasive breast cancers and its functions in cancer vasculature. Immunohistochemical analysis showed that AGM was highly expressed in cancer vasculature even in ductal carcinoma in situ (DCIS) as compared to normal vasculature, while its expression in CAFs was more prominent in invasive carcinomas than DCIS. In vitro analyses showed that AGM was strongly induced by vascular endothelial cell growth factor (VEGF) in vascular endothelial cells. Although AGM stimulated neither the growth nor migration of endothelial cells, it supported efficient adhesion of endothelial cells. Integrin ?v?3 was identified as a novel major receptor for AGM in vascular endothelial cells. AGM retracted endothelial cells by inducing actin stress fibers and loosened their VE-cadherin-mediated intercellular junction. Consequently, AGM increased vascular permeability both in vitro and in vivo. Furthermore, AGM and integrin ?v?3 were highly expressed and colocalized in cancer vasculature. These results suggest that AGM cooperates with VEGF to induce the aberrant functions of cancer vasculature as a ligand of integrin ?v?3. PMID:24737780

Komiya, Eriko; Sato, Hiroki; Watanabe, Naoko; Ise, Marii; Higashi, Shouichi; Miyagi, Yohei; Miyazaki, Kaoru

2014-01-01

68

Angiomodulin, a marker of cancer vasculature, is upregulated by vascular endothelial growth factor and increases vascular permeability as a ligand of integrin ?v?3.  

PubMed

Angiomodulin (AGM) is a member of insulin-like growth factor binding protein (IGFBP) superfamily and often called IGFBP-rP1 or IGFBP-7. AGM was originally identified as a tumor-derived cell adhesion factor, which was highly accumulated in blood vessels of human cancer tissues. AGM is also overexpressed in cancer-associated fibroblasts (CAFs) and activates fibroblasts. However, some studies have shown tumor-suppressing activity of AGM. To understand the roles of AGM in cancer progression, we here investigated the expression of AGM in benign and invasive breast cancers and its functions in cancer vasculature. Immunohistochemical analysis showed that AGM was highly expressed in cancer vasculature even in ductal carcinoma in situ (DCIS) as compared to normal vasculature, while its expression in CAFs was more prominent in invasive carcinomas than DCIS. In vitro analyses showed that AGM was strongly induced by vascular endothelial cell growth factor (VEGF) in vascular endothelial cells. Although AGM stimulated neither the growth nor migration of endothelial cells, it supported efficient adhesion of endothelial cells. Integrin ?v?3 was identified as a novel major receptor for AGM in vascular endothelial cells. AGM retracted endothelial cells by inducing actin stress fibers and loosened their VE-cadherin-mediated intercellular junction. Consequently, AGM increased vascular permeability both in vitro and in vivo. Furthermore, AGM and integrin ?v?3 were highly expressed and colocalized in cancer vasculature. These results suggest that AGM cooperates with VEGF to induce the aberrant functions of cancer vasculature as a ligand of integrin ?v?3. PMID:24737780

Komiya, Eriko; Sato, Hiroki; Watanabe, Naoko; Ise, Marii; Higashi, Shouichi; Miyagi, Yohei; Miyazaki, Kaoru

2014-06-01

69

Diesel exhaust particles modulate vascular endothelial cell permeability: implication of ZO-1 expression.  

PubMed

Exposure to air pollutants increases the incidence of cardiovascular disease. Recent toxicity studies revealed that ultra-fine particles (UFP, d(p)<100-200 nm), the major portion of particulate matter (PM) by numbers in the atmosphere, induced atherosclerosis. In this study, we posited that variations in chemical composition in diesel exhausted particles (DEP) regulated endothelial cell permeability to a different extent. Human aortic endothelial cells (HAEC) were exposed to well-characterized DEP (d(p)<100 nm) emitted from a diesel engine in either idling mode (DEP1) or in urban dynamometer driving schedule (UDDS) (DEP2). Horse Radish Peroxidase-Streptavidin activity assay showed that DEP2 increased endothelial permeability to a greater extent than DEP1 (control=0.077+/-0.005, DEP1=0.175+/-0.003, DEP2=0.265+/-0.006, n=3, p<0.01). DEP2 also down-regulated tight junction protein, Zonular Occludin-1 (ZO-1), to a greater extent compared to DEP1. LDH and caspase-3 activities revealed that DEP-mediated increase in permeability was not due to direct cytotoxicity, and DEP-mediated ZO-1 down-regulation was not due to a decrease in ZO-1 mRNA. Hence, our findings suggest that DEP1 vs. DEP2 differentially influenced the extent of endothelial permeability at the post-translational level. This increase in endothelium permeability is implicated in inflammatory cell transmigration into subendothelial layers with relevance to the initiation of atherosclerosis. PMID:20576493

Li, Rongsong; Ning, Zhi; Cui, Jeffrey; Yu, Fei; Sioutas, Constantinos; Hsiai, Tzung

2010-09-01

70

Diesel exhaust particles modulate vascular endothelial cell permeability: Implication of ZO-1 Expression  

PubMed Central

Exposure to air pollutants increases the incidence of cardiovascular disease. Recent toxicity studies revealed that ultra fine particles (UFP, dp<100–200 nm), the major portion of particulate matter (PM) by numbers in the atmosphere, induced atherosclerosis. In this study, we posited that variations in chemical composition in diesel exhausted particles (DEP) regulated endothelial cell permeability to a different extent. Human aortic endothelial cells (HAEC) were exposed to well-characterized DEP (dp<100 nm) emitted from a diesel engine in either idling mode (DEP1) or in urban dynamometer driving schedule (UDDS) (DEP2). Horse Radish Peroxidase-Streptavidin activity assay showed that DEP2 increased endothelial permeability to a greater extent than DEP1 (Control=0.077± 0.005, DEP1=0.175±0.003, DEP2=0.265±0.006, n=3, p<0.01). DEP2 also down-regulated tight junction protein, Zonular Occludin-1 (ZO-1), to a greater extent compared to DEP1. LDH and caspase-3 activities revealed that DEP-mediated increase in permeability was not due to direct cytotoxicity, and DEP-mediated ZO-1 down-regulation was not due to a decrease in ZO-1 mRNA. Hence, our findings suggest that DEP1 versus DEP2 differentially influenced the extent of endothelial permeability at the post-translational level. This increase in endothelium permeability is implicated in inflammatory cell transmigration into subendothelial layers with relevance to the initiation of atherosclerosis. PMID:20576493

Li, Rongsong; Ning, Zhi; Cui, Jeffrey; Yu, Fei; Sioutas, Constantinos; Hsiai, Tzung

2010-01-01

71

Neuron-derived semaphorin 3A is an early inducer of vascular permeability in diabetic retinopathy via neuropilin-1.  

PubMed

The deterioration of the inner blood-retinal barrier and consequent macular edema is a cardinal manifestation of diabetic retinopathy (DR) and the clinical feature most closely associated with loss of sight. We provide evidence from both human and animal studies for the critical role of the classical neuronal guidance cue, semaphorin 3A, in instigating pathological vascular permeability in diabetic retinas via its cognate receptor neuropilin-1. We reveal that semaphorin 3A is induced in early hyperglycemic phases of diabetes within the neuronal retina and precipitates initial breakdown of endothelial barrier function. We demonstrate, by a series of orthogonal approaches, that neutralization of semaphorin 3A efficiently prevents diabetes-induced retinal vascular leakage in a stage of the disease when vascular endothelial growth factor neutralization is inefficient. These observations were corroborated in Tg(Cre-Esr1)/Nrp1(flox/flox) conditional knockout mice. Our findings identify a therapeutic target for macular edema and provide further evidence for neurovascular crosstalk in the pathogenesis of DR. PMID:24093675

Cerani, Agustin; Tetreault, Nicolas; Menard, Catherine; Lapalme, Eric; Patel, Chintan; Sitaras, Nicholas; Beaudoin, Felix; Leboeuf, Dominique; De Guire, Vincent; Binet, François; Dejda, Agnieszka; Rezende, Flavio A; Miloudi, Khalil; Sapieha, Przemyslaw

2013-10-01

72

Acute Stress Results in Skin Corticotropin-Releasing Hormone Secretion, Mast Cell Activation and Vascular Permeability, an Effect Mimicked by Intradermal Corticotropin-Releasing Hormone and Inhibited by Histamine1 Receptor Antagonists  

Microsoft Academic Search

Background: Mast cells play an important role in allergic inflammation by releasing vasoactive molecules, proteases and cytokines. Corticotropin-releasing hormone (CRH) and its structural analogue urocortin (Ucn) were shown to trigger skin mast cell activation and vascular permeability. We investigated the effect of acute stress on rat skin vascular permeability and CRH secretion, as well as the effect of intradermal CRH,

Michael Lytinas; Duraisamy Kempuraj; Man Huang; William Boucher; Pamela Esposito; Theoharis C. Theoharides

2003-01-01

73

Hyperstimulation and a gonadotropin-releasing hormone agonist modulate ovarian vascular permeability by altering expression of the tight junction protein claudin-5.  

PubMed

We investigated the mechanism by which a GnRH agonist (GnRHa) affects ovarian vascularity, vascular permeability, and expression of the tight junction protein claudin-5 in a rat model of ovarian hyperstimulation syndrome (OHSS). Hyperstimulated rats received excessive doses of pregnant mare serum gonadotropin (PMSG; 50 IU/d) for 4 consecutive days, from d 25 to 28 of life, followed by 25 IU human chorionic gonadotropin (hCG) on d 29. Control rats received 10 IU PMSG on d 27 of life, followed by 10 IU hCG on d 29. GnRHa (leuprolide 100 microg/kg.d) was administered to some hyperstimulated rats either on d 29 and 30 (short-term GnRHa treatment) or from d 25 to 30 (long-term GnRHa treatment). Ovarian vascular density (vessels per 10 mm(2)) and vessel endothelial area (percent) were assessed by immunohistochemical analysis of the distribution of von Willebrand factor, whereas vascular permeability was evaluated based on leakage of Evans blue. High doses of PMSG and hCG significantly increased ovarian weight, vascular permeability, vascular density, and the vessel endothelial area and significantly reduced expression of claudin-5 protein and mRNA. All of these effects were significantly and dose-dependently inhibited by administration of GnRHa. This suggests that reduced expression of claudin-5 plays a crucial role in the increased ovarian vascular permeability seen in OHSS and that its expression can be modulated by GnRHa treatment. Indeed, preventing redistribution of tight junction proteins in endothelial cells and the resultant loss of endothelial barrier architecture might be the key to protecting patients against massive extravascular fluid accumulation in cases of OHSS. PMID:16269461

Kitajima, Yoshimitsu; Endo, Toshiaki; Nagasawa, Kunihiko; Manase, Kengo; Honnma, Hiroyuki; Baba, Tsuyoshi; Hayashi, Takuhiro; Chiba, Hideki; Sawada, Norimasa; Saito, Tsuyoshi

2006-02-01

74

Studies of Vascular Permeability Factor derived from T Lymphocytes and Inhibitory Effect of Plasma on Its Production in Minimal Change Nephrotic Syndrome  

Microsoft Academic Search

Peripheral T lymphocytes from patients with minimal change nephrotic syndrome (MCNS) and controls were treated for their ability to produce vascular permeability factors (VPF) without concanavalin A stimulation. In vitro cultures of T lymphocytes from active MCNS produced VPF in the supernatant, whereas T lymphocytes from inactive MCNS or normal subjects did not. Furthermore, the plasma from patients with active

S. Tomizawa; K. Maruyama; N. Nagasawa; S. Suzuki; T. Kuroume

1985-01-01

75

A new NK1 receptor antagonist (CP-99,994) prevents the increase in tracheal vascular permeability produced by hypertonic saline.  

PubMed

The increase in tracheal vascular permeability evoked by hypertonic saline depends on capsaicin-sensitive sensory nerves, which contain substance P and other neuropeptides. The present study was performed to determine whether a novel, nonpeptide, selective antagonist of the NK1 tachykinin receptor CP-99,994, [(+)-(2S-3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine], can prevent the effect of substance P, capsaicin and hypertonic saline on tracheal vascular permeability. CP-99,994 was also tested against a nonpeptide inflammatory mediator, platelet-activating factor (PAF), to assess the selectivity of its action. Anesthetized F-344 rats were injected with either substance P (5 micrograms/kg i.v.), capsaicin (100 micrograms/kg i.v.) or PAF (10 micrograms/kg i.v.), or were exposed to ultrasonically nebulized 3.6% NaCl. In each group, some of the rats were pretreated with CP-99,994 (1 to 4 mg/kg i.v.), and some with its vehicle (0.9% NaCl). Groups of rats injected with substance P or exposed to hypertonic saline were pretreated with the (2R, 3R)-enantiomer CP-100,263, [(-)-(2R-3R)-3-(2-methoxybenzylamino)-2-phenylpiperidine] (2 or 4 mg/kg i.v.). The magnitude of the increase in tracheal vascular permeability was measured by quantifying the extravasation of Evans blue dye. CP-99,994 prevented the increase in tracheal vascular permeability produced by inhalation of hypertonic saline, by substance P and by capsaicin, but did not prevent the effect of PAF. CP-100,263 did not affect substance P- and hypertonic saline-induced increase in vascular permeability. These results indicate that the NK1 receptor antagonist CP-99,994 produces stereoselective inhibition of neurogenic plasma extravasation evoked by inhalation of hypertonic saline. PMID:7687291

Piedimonte, G; Bertrand, C; Geppetti, P; Snider, R M; Desai, M C; Nadel, J A

1993-07-01

76

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

77

Investigating the turbulent to laminar flow transition across a permeable wall using Refractive-Index Matching (RIM)  

NASA Astrophysics Data System (ADS)

Permeable boundaries occur in a variety of natural environments. Turbulent flow overlying such boundaries is perhaps one of the most common, yet one of the most complex, types of flow found in any geophysical environment (e.g. river beds, forests). Unlike flows over impermeable walls, which have been widely studied, the characteristics of flow generated by permeable walls is relatively poorly understood. This work considers the flow both above and within a permeable bed focusing on the linkage between the free flow and the Darcian layer through an experimental investigation of the transitional (Brinkman) layer. To overcome the challenges related with the complex geometry of porous structures, a Refractive-Index-Matching (RIM) approach was employed to gain full optical access to the fluid flowing across a permeable wall. A permeable wall, made by packing acrylic spheres in a cubic arrangement, was immersed in an aqueous solution of Sodium Iodide (NaI). With such an arrangement the refractive index of the two phases was accurately matched, thus providing unobstructed optical access within the permeable bed. Data was collected on the flow across the wall interface and the turbulent attributes of these surface-subsurface interactions were quantified. The first part of this paper highlights the fundamental differences between flows above permeable and impermeable beds, and examines the implications of these differences for the mechanisms of mass and momentum exchange. For example, permeable beds have significant injection and suction events that move fluid across the interface, and result in an absence of low-speed streaks that are ubiquitous over impermeable beds. Additionally, in contrast to flow over impermeable surfaces, ejection events dominate over sweep events above a permeable wall, this has significant implications for the mechanisms of drag and thus energy dissipation that occur within the transition layer. The second part of the paper examines the complexity of flow within the pores of the transition layer. This new data suggests that the manner in which the transition layer is commonly represented in current numerical models may be inappropriate, and that future work must better account for flow across this dynamic interface.

Kim, T.; Blois, G.; Christensen, K. T.; Best, J.; Sambrook Smith, G.

2013-12-01

78

Stabilizing the VE-cadherin–catenin complex blocks leukocyte extravasation and vascular permeability  

PubMed Central

To determine whether leukocytes need to open endothelial cell contacts during extravasation, we decided to generate mice with strongly stabilized endothelial junctions. To this end, we replaced VE-cadherin genetically by a VE-cadherin–?-catenin fusion construct. Such mice were completely resistant to the induction of vascular leaks by VEGF or histamine. Neutrophil or lymphocyte recruitment into inflamed cremaster, lung and skin were strongly inhibited in these mice, documenting the importance of the junctional route in vivo. Surprisingly, lymphocyte homing into lymph nodes was not inhibited. VE-cadherin–?-catenin associated more intensely with the actin cytoskeleton as demonstrated by its membrane mobility and detergent extractability. Our results establish the junctional route as the main pathway for extravasating leukocytes in several, although not in all tissues. Furthermore, in these tissues, plasticity of the VE-cadherin–catenin complex is central for the leukocyte diapedesis mechanism. PMID:21857650

Schulte, Dörte; Küppers, Verena; Dartsch, Nina; Broermann, Andre; Li, Hang; Zarbock, Alexander; Kamenyeva, Olena; Kiefer, Friedemann; Khandoga, Alexander; Massberg, Steffen; Vestweber, Dietmar

2011-01-01

79

Inhibitory effect of a novel bradykinin B1 receptor antagonist, R-954, on enhanced vascular permeability in type 1 diabetic mice.  

PubMed

The morbidity and mortality associated with type 1 diabetes are essentially related to the micro- and macrovascular complications that develop over time and lead to several diabetic complications, including hypertension, atherosclerosis, and retinopathy, as well as coronary and renal failure. Normally absent in physiological conditions, the bradykinin B1 receptor (BKB1-R) was recently found to be overexpressed in pathological conditions, including type 1 diabetes. In the present study, we evaluated the effect of the new BKB1-R antagonist, R-954 (Ac-Orn-[Oic2, alpha-MePhe5, D-betaNal7, Ile8]desArg9-bradykinin, on the increase in vascular permeability in streptozotocin (STZ)-diabetic mice. The capillary permeability to albumin was measured by quantifying the extravasation of albumin-bound Evans blue dye in selected target tissues (liver, pancreas, duodenum, ileum, spleen, heart, kidney, stomach, skin, muscle, and thyroid gland). Acute single administration of R-954 (300 microg/kg, i.v.) to type 1 diabetic mice 4 weeks after STZ significantly inhibited the enhanced vascular permeability in most tissues. These data provide further experimental evidence for the implication of BKB1-R in the enhanced vascular permeability associated with type 1 diabetes. PMID:12564648

Simard, Bryan; Gabra, Bichoy H; Sirois, Pierre

2002-12-01

80

Increased vascular permeability in organs mediated by the systemic administration of lymphokine-activated killer cells and recombinant interleukin-2 in mice.  

PubMed

Significant tumor regressions in mice with established carcinomas, sarcomas, and melanomas and in humans with advanced cancers have been observed following immunotherapy with lymphokine-activated killer (LAK) cells and recombinant interleukin-2 (IL-2). However, dose escalations of LAK cells and IL-2 have been prevented by the development of a vascular leak syndrome (VLS). Although IL-2 alone can produce this VLS, we investigated the role of transferred LAK cells, generated by the incubation of syngeneic splenocytes in IL-2, in mediating this phenomenon. We used a murine model to quantitate the vascular leak by measuring the extravasation of iv injected 125I-bovine serum albumin. A permeability index (PI) was calculated by dividing the mean cpm of tissues from treated mice by those from control animals. The systemic transfer of LAK cells and IL-2 produced a significantly greater extravasation of albumin in the lungs, liver, and kidneys than after Hanks' balanced salt solution, IL-2, or LAK cells alone (in the lungs, for example, PI = 4.7, 1.4, and 1.6 after LAK cells and IL-2, LAK cells alone, and IL-2 alone, respectively). To eliminate the contribution to the leak by host lymphocytes, we irradiated mice before cell transfer. As compared to controls, LAK cells and IL-2 resulted in higher extravasation in the lungs, liver, kidneys, and spleen. However, a similar vascular leak was not observed in the lungs, liver, and kidneys after treatment with IL-2 plus fresh or cultured (without IL-2) splenocytes. Moreover, the combination of IL-2 excipient and LAK cells or IL-2 and irradiated LAK cells did not produce a fluid leak. The development of the VLS by LAK cells was directly related to the dose of concurrently administered IL-2 and the number of injected cells. Depletion of Thy 1.2-positive lymphocytes using antibody and complement prior to generating the LAK cells used in adoptive transfer did not abrogate the VLS in any of the organs tested. Similarly, depletion of L3T4 and Lyt-2 positive cells in vivo using monoclonal antibodies prior to harvesting spleens for generation of LAK cells also had no impact on the VLS. In contrast, in vitro treatment of LAK precursor cells with antibody to asialo-GM-1 plus complement completely eliminated the VLS when the depleted cells were cultured in IL-2 and subsequently transferred.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3258039

Ettinghausen, S E; Puri, R K; Rosenberg, S A

1988-04-01

81

Enhanced vascular permeability facilitates entry of plasma HDL and promotes macrophage-reverse cholesterol transport from skin in mice.  

PubMed

Reverse cholesterol transport (RCT) pathway from macrophage foam cells initiates when HDL particles cross the endothelium, enter the interstitial fluid, and induce cholesterol efflux from these cells. We injected [(3)H]cholesterol-loaded J774 macrophages into the dorsal skin of mice and measured the transfer of macrophage-derived [(3)H]cholesterol to feces [macrophage-RCT (m-RCT)]. Injection of histamine to the macrophage injection site increased locally vascular permeability, enhanced influx of intravenously administered HDL, and stimulated m-RCT from the histamine-treated site. The stimulatory effect of histamine on m-RCT was abolished by prior administration of histamine H1 receptor (H1R) antagonist pyrilamine, indicating that the histamine effect was H1R-dependent. Subcutaneous administration of two other vasoactive mediators, serotonin or bradykinin, and activation of skin mast cells to secrete histamine and other vasoactive compounds also stimulated m-RCT. None of the studied vasoactive mediators affected serum HDL levels or the cholesterol-releasing ability of J774 macrophages in culture, indicating that acceleration of m-RCT was solely due to increased availability of cholesterol acceptors in skin. We conclude that disruption of the endothelial barrier by vasoactive compounds enhances the passage of HDL into interstitial fluid and increases the rate of RCT from peripheral macrophage foam cells, which reveals a novel tissue cholesterol-regulating function of these compounds. PMID:25473102

Kareinen, Ilona; Cedó, Lídia; Silvennoinen, Reija; Laurila, Pirkka-Pekka; Jauhiainen, Matti; Julve, Josep; Blanco-Vaca, Francisco; Escola-Gil, Joan Carles; Kovanen, Petri T; Lee-Rueckert, Miriam

2015-02-01

82

Tityus serrulatus venom increases vascular permeability in selected airway tissues in a mast cell-independent way.  

PubMed

Tityus serrulatus venom (Tsv)-induced pulmonary edema can occur in severe envenomation and the mechanisms involved are not completely understood. Therefore, we studied the effect of pharmacological modulation of the mast cell activation and the histamine antagonism on airways edema (investigated by Evans blue dye extravasation) and measured 5-hydroxytryptamine (5-HT) concentration in bronchoalveolar lavage fluid (BALF) in rats envenomed by Tsv. Additionally, the in vitro effect of Tsv on mast cells was studied using histological method and 5-HT release from mesenteric and peritoneal mast cells. We found that i.v. injection of Tsv increase vascular permeability in trachea, upper and lower bronchi and in lung parenchyma. This was not affected by ketotifen, a mast cell "stabilizer," or by pretreatment with pyrilamine (histamine H1 receptor antagonist). Moreover, 5-HT was not found in BALF of envenomed rats. In vitro experiments showed that Tsv did not induce mast cell degranulation nor release of 5-HT by mesenteric or peritoneal mast cells, in sharp contrast to preparations challenged by a mast cell activator, compound 48/80. In conclusion, our results show that Tsv causes strong edema in rat airways which is independent of mast cell activation and show that mast cells are not directly activated by Tsv. PMID:21920722

Zuliani, Juliana P; Freitas, Thalma A; Conceição, Isaltino M; Kwasniewski, Fábio H

2013-03-01

83

Anti-inflammatory properties of Bridelia ferruginea stem bark. Inhibition of lipopolysaccaride-induced septic shock and vascular permeability.  

PubMed

The anti-inflammatory activity of the aqueous extract of Bridelia ferruginea stem bark was further evaluated in models which are mediated by tumour necrosis factor-alpha (TNFalpha). The effect of the extract on lipopolysaccharide (LPS)-induced septic shock was evaluated by measuring the number of deaths and the levels of serum alanine and aspartate aminotransferases following intraperitoneal injection of LPS (1 microg/kg) into D-galactosamine-primed mice. LPS-induced vascular permeability on the back skin of mice was measured by the local accumulation of Evan's blue after subcutaneous injection of LPS. Pre-treatment with Bridelia ferruginea extract (10-80 mg/kg) produced a dose-dependent inhibition of the septic shock syndrome in mice, with 80 mg/kg of the extract exhibiting comparable activity as pentoxifylline (100 mg/kg). LPS-induced dye leakage in the skin of mice was also suppressed by the extract (10-80 mg/kg). Our study suggests that one of the mechanisms of the anti-inflammatory effects of Bridelia ferruginea possibly involve the suppression of TNFalpha up-regulation. PMID:12963146

Olajide, Olumayokun A; Okpako, David T; Makinde, Janet M

2003-10-01

84

Relationship between cardio-ankle vascular index and plasma lipids in hypertension subjects.  

PubMed

An increasing of arterial stiffness is the path physiological characteristic of hypertension. Cardio-ankle vascular index (CAVI) is a new index of arterial stiffness. In the present study, we investigated the relationship between CAVI and plasma lipids in hypertension subjects. A total of 542 subjects (male/female 336/206) from the Department of Vascular Medicine were divided into two groups: healthy group (n=402) and hypertension group (n=140). CAVI was measured with VS-1000 apparatus. Our results showed that the levels of CAVI, body mass index (BMI), fast blood glucose (FBG), uric acid (UA) and triglycerides (TGs) were significantly higher in the hypertension group than in the control group (all P<0.01). High-density lipoprotein cholesterol (HDL-C) was significantly lower in the hypertension group than in the control group (P<0.001). CAVI was positively correlated with FBG, UA, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and TG in the entire study group. Negative correlation between CAVI and HDL-C was found in the entire group even after adjusting for age, gender and blood pressure. In addition, there was negative correlation between CAVI and HDL-C in the control group. However, there was negative relational tendency between CAVI and HDL-C in hypertension subjects without significant difference. Multiple linear regression analysis showed that age, BMI, FBG, TG and heart rate were independent associating factors of CAVI in all subjects. Age, FBG and Cr were independent associating factors of CAVI in the hypertension group. Our present study showed that CAVI was significantly higher in hypertension subjects, and metabolic accompaniments might involve the increasing of arterial stiffness in hypertension patients. PMID:24831100

Wang, H; Liu, J; Zhao, H; Zhao, X; Li, L; Shi, H; Zhan, S; Liu, J

2015-02-01

85

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

86

Changes in pericytic expression of NG2 and PDGFRB and vascular permeability in the sensory circumventricular organs of adult mouse by osmotic stimulation.  

PubMed

The blood-brain barrier (BBB) is a barrier that prevents free access of blood-derived substances to the brain through the tight junctions and maintains a specialized brain environment. Circumventricular organs (CVOs) lack the typical BBB. The fenestrated vasculature of the sensory CVOs, including the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO) and area postrema (AP), allows parenchyma cells to sense a variety of blood-derived information, including osmotic ones. In the present study, we utilized immunohistochemistry to examine changes in the expression of NG2 and platelet-derived growth factor receptor beta (PDGFRB) in the OVLT, SFO and AP of adult mice during chronic osmotic stimulation. The expression of NG2 and PDGFRB was remarkably prominent in pericytes, although these angiogenesis-associated proteins are highly expressed at pericytes of developing immature vasculature. The chronic salt loading prominently increased the expression of NG2 in the OVLT and SFO and that of PDGFRB in the OVLT, SFO and AP. The vascular permeability of low-molecular-mass tracer fluorescein isothiocyanate was increased significantly by chronic salt loading in the OVLT and SFO but not AP. In conclusion, the present study demonstrates changes in pericyte expression of NG2 and PDGFRB and vascular permeability in the sensory CVOs by chronic osmotic stimulation, indicating active participation of the vascular system in osmotic homeostasis. PMID:23629811

Morita, Shoko; Hourai, Atsushi; Miyata, Seiji

2014-01-01

87

Purification and biochemical characterization of a fibrin(ogen)olytic metalloprotease from Macrovipera mauritanica snake venom which induces vascular permeability.  

PubMed

In the present study, a novel fibrin(ogen)olytic metalloprotease from Macrovipera mauritanica snake venom was purified and characterized in terms of enzyme kinetics and substrate specificity. The purified enzyme [termed snake venom metalloprotease-Macrovipera mauritanica (SVMP?MM)] was composed of a single polypeptide with an apparent molecular weight of 27 kDa, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminus of the enzyme was composed of NH(2)-QRFAPRYIEL-COOH, as determined by N-terminal sequencing. The A?- and the B?-chains of fibrinogen were completely cleaved by SVMP-MM within 20 and 480 min, respectively. However, the ?-chain was much more resistant to digestion by the enzyme. The enzyme also exhibited proteolytic activity, cleaving the ?-? polymer of cross-linked fibrin, but did not effectively digest the ?-? polymer. To determine the kinetic parameters for SVMP-MM, a fluorescence-quenching peptide (termed o-aminobenzoic acid-HTEKLVTS-2,4-dinitrophenyl?NH(2)) containing a K-L sequence for SVMP-MM cleavage was designed and synthesized. The optimal pH and temperature for the enzyme activity were found to be 5.5 and 37?C, respectively, when the fluorogenic substrate was synthesized and used as a substrate. Among the various divalent cations tested, Ni(2+) and Cu(2+) showed strong inhibitory effects on enzyme activity, with an average of 69.6% inhibition. The enzyme activity was also inhibited by treatment with 1,10-phenanthroline, ethylenediaminetetraacetic acid and glycol-bis-(2?aminoethylether)-N,N,N',N'-tetra-acetic acid, but not with aprotinin, tosyl-lysine chloromethyl ketone and tosyl-phenylalanyl chloromethyl ketone, suggesting that SVMP-MM is a metalloprotease and not a serine protease. The enzymatic parameters, including the K(M), k(cat), and k(cat)/K(M) values were estimated to be 0.015 mM, 0.031 sec(-1), and 20.67 mM(-1)sec(-1), respectively. SVMP-MM induced vascular permeability by digesting type IV collagen. The results obtained in our study demonstrate that SVMP-MM is a fibrin(ogen)olytic P-I class metalloprotease, which can induce a hemorrhagic reaction in vivo. PMID:25069477

Lee, Eun Hee; Park, Jung Eun; Park, Jong Woo; Lee, Jung Sup

2014-10-01

88

Magnetic resonance imaging measurements of vascular permeability and extracellular volume fraction of breast tumors by dynamic Gd-DTPA-enhanced relaxometry.  

PubMed

Vascular permeability (k(ep), min(-1)) and extracellular volume fraction (v(e)) are tissue parameters of great interest to characterize malignant tumor lesions. Indeed, it is well known that tumors with high blood supply better respond to therapy than poorly vascularized tumors, and tumors with large extracellular volume tend to be more malignant than tumors showing lower extracellular volume. Furthermore, the transport of therapeutic agents depends on both extracellular volume fraction and vessel permeability. Thus, before treatment, these tissue parameters may prove useful to evaluate tumor aggressiveness and to predict responsiveness to therapy and variations during cytotoxic therapies could allow to assess treatment efficacy and early modified therapy schedules in case of poor responsiveness. As a consequence, there is a need to develop methods that could be routinely used to determine these tissue parameters. In this work, blood-tissue permeability and extracellular volume fraction information were derived from magnetic resonance imaging dynamic longitudinal relaxation rate (R(1)) mapping obtained after an intravenous bolus injection of Gd-DTPA in a group of 92 female patients with breast lesions, 68 of these being histologically proven to be with carcinoma. For the sake of comparison, 24 benign lesions were studied. The measurement protocol based on two-dimensional gradient echo sequences and a monoexponential plasma kinetic model was that validated in the occasion of previous animal experiments. As a consequence of neoangiogenesis, results showed a higher permeability in malignant than in benign lesions, whereas the extracellular volume fraction value did not allow any discrimination between benign and malignant lesions. The method, which can be easily implemented whatever the imaging system used, could advantageously be used to quantify lesion parameters (k(ep) and v(e)) in routine clinical imaging. Because of its large reproducibility, the method could be useful for intersite comparisons and follow-up studies. PMID:17371717

Vincensini, Dominique; Dedieu, Véronique; Eliat, Pierre A; Vincent, Corine; Bailly, Corine; de Certaines, Jacques; Joffre, Francis

2007-04-01

89

Negative real parts of the equivalent permittivity, permeability, and refractive index of sculptured-nanorod arrays of silver  

SciTech Connect

Thin films comprising parallel nanorods were deposited by directing silver vapor obliquely toward a plane substrate. The direction of the vapor flux was varied in two different ways to sculpture the nanorods in different shapes. The reflection and transmission coefficients of the thin films were measured at three wavelengths in the visible regime for normal-illumination conditions for two linear-polarization states, using walk-off interferometry and polarization interferometry. The authors found that sculpturing significantly affects the signs of the real parts of the equivalent permittivity, permeability, and refractive index of the silver thin films for the two polarization states at different wavelengths. Thus, vapor deposition combined with sculpturing can be useful for large-scale production of materials having different equivalent constitutive parameters with negative real parts.

Jen, Yi-Jun; Lakhtakia, Akhlesh; Yu, Ching-Wei; Wang, Yu-Hsiung [Department of Electro-Optical Engineering, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Road, Taipei 106, Taiwan (China); Department of Engineering Science and Mechanics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Electro-Optical Engineering, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Road, Taipei 106, Taiwan (China)

2010-09-15

90

Augmented EPR effect by photo-triggered tumor vascular treatment improved therapeutic efficacy of liposomal paclitaxel in mice bearing tumors with low permeable vasculature.  

PubMed

The effects of photo-triggered tumor vascular treatment (PVT) on the structural and functional properties of tumor vasculature were assessed in Colon-26 (C26) and B16/BL6 (B16) tumor-bearing mice. Furthermore, anti-tumor efficacy of subsequently injected PEG liposomal paclitaxel (PL-PTX) was also evaluated. As a photosensitizer, a hydrophobic porphyrin derivative was used and formulated in polymeric nanoparticle composed of polyethylene glycol-block-polylactic acid to avoid its non-specific in vivo disposition. In the mice bearing C26 with high permeable vasculature, the prominent anti-tumor activity was confirmed by PVT alone, but the subsequently injected PL-PTX did not show any additive effect. PVT itself initially induced apoptotic cell death of tumor vascular endothelial cells and platelet aggregation, which would have subsequently induced apoptosis of C26 tumor cells surrounding the vasculature. On the other hand, in the mice bearing B16 with low permeable vasculature, PVT enhanced the anti-tumor activity of subsequently injected PL-PTX, which would be attributed to the tumor disposition amount and area of PEG liposomes enhanced by PVT. These results clearly indicated that the treatment would have made it possible to provide more efficient extravasation of PL-PTX, leading to its more potent anti-tumor effect. PMID:25553829

Araki, Tomoya; Ogawara, Ken-Ichi; Suzuki, Haruka; Kawai, Rie; Watanabe, Taka-Ichi; Ono, Tsutomu; Higaki, Kazutaka

2015-02-28

91

Effects of Telmisartan on Arterial Stiffness Assessed by the Cardio-Ankle Vascular Index in Hypertensive Patients  

Microsoft Academic Search

Background\\/Aims: This study was conducted to determine the effect of telmisartan on the cardio-ankle vascular index (CAVI), a novel blood pressure (BP)-independent marker for arterial stiffness in hypertensive patients. Methods: One hundred consecutive hypertensive patients were randomly assigned either to a group treated with calcium channel blocker (CCB)-based therapy or a group treated with telmisartan-based therapy. Clinical and biological parameters

Kenichiro Kinouchi; Atsuhiro Ichihara; Mariyo Sakoda; Asako Kurauchi-Mito; Kanako Murohashi-Bokuda; Hiroshi Itoh

2010-01-01

92

The Cytokine Response of U937-Derived Macrophages Infected through Antibody-Dependent Enhancement of Dengue Virus Disrupts Cell Apical-Junction Complexes and Increases Vascular Permeability  

PubMed Central

Severe dengue (SD) is a life-threatening complication of dengue that includes vascular permeability syndrome (VPS) and respiratory distress. Secondary infections are considered a risk factor for developing SD, presumably through a mechanism called antibody-dependent enhancement (ADE). Despite extensive studies, the molecular bases of how ADE contributes to SD and VPS are largely unknown. This work compares the cytokine responses of differentiated U937 human monocytic cells infected directly with dengue virus (DENV) or in the presence of enhancing concentrations of a humanized monoclonal antibody recognizing protein E (ADE-DENV infection). Using a cytometric bead assay, ADE-DENV-infected cells were found to produce significantly higher levels of the proinflammatory cytokines interleukin 6 (IL-6), IL-12p70, and tumor necrosis factor alpha (TNF-?), as well as prostaglandin E2 (PGE2), than cells directly infected. The capacity of conditioned supernatants (conditioned medium [CM]) to disrupt tight junctions (TJs) in MDCK cell cultures was evaluated. Exposure of MDCK cell monolayers to CM collected from ADE-DENV-infected cells (ADE-CM) but not from cells infected directly led to a rapid loss of transepithelial electrical resistance (TER) and to delocalization and degradation of apical-junction complex proteins. Depletion of either TNF-?, IL-6, or IL-12p70 from CM from ADE-DENV-infected cells fully reverted the disrupting effect on TJs. Remarkably, mice injected intraperitoneally with ADE-CM showed increased vascular permeability in sera and lungs, as indicated by an Evans blue quantification assay. These results indicate that the cytokine response of U937-derived macrophages to ADE-DENV infection shows an increased capacity to disturb TJs, while results obtained with the mouse model suggest that such a response may be related to the vascular plasma leakage characteristic of SD. PMID:23616663

Puerta-Guardo, Henry; Raya-Sandino, Arturo; González-Mariscal, Lorenza; Rosales, Victor H.; Ayala-Dávila, José; Chávez-Mungía, Bibiana; Martínez-Fong, Daniel; Medina, Fernando

2013-01-01

93

Palomid 529, a Novel Small-Molecule Drug, Is a TORC1/TORC2 Inhibitor That Reduces Tumor Growth, Tumor Angiogenesis, and Vascular Permeability  

PubMed Central

It has become clear that the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is central for promoting both tumor and tumor stroma and is therefore a major target for anticancer drug development. First- and second-generation rapalogs (prototypical mTOR inhibitors) have shown promise but, due to the complex nature of mTOR signaling, can result in counterproductive feedback signaling to potentiate upstream Akt signaling. We present a novel PI3K/Akt/mTOR inhibitor, Palomid 529 (P529), which inhibits the TORC1 and TORC2 complexes and shows both inhibition of Akt signaling and mTOR signaling similarly in tumor and vasculature. We show that P529 inhibits tumor growth, angiogenesis, and vascular permeability. It retains the beneficial aspects of tumor vascular normalization that rapamycin boasts. However, P529 has the additional benefit of blocking pAktS473 signaling consistent with blocking TORC2 in all cells and thus bypassing feedback loops that lead to increased Akt signaling in some tumor cells. [Cancer Res 2008;68(22):9551–7] PMID:19010932

Xue, Qi; Hopkins, Benjamin; Perruzzi, Carole; Udayakumar, Durga; Sherris, David; Benjamin, Laura E.

2009-01-01

94

Angiopoietin-like 4 prevents metastasis through inhibition of vascular permeability and tumor cell motility and invasiveness  

PubMed Central

Angiopoietin-like 4 (ANGPTL4), a secreted protein of the angiopoietin-like family, is induced by hypoxia in both tumor and endothelial cells as well as in hypoxic perinecrotic areas of numerous cancers. Here, we investigated whether ANGPTL4 might affect tumor growth as well as metastasis. Metastatic 3LL cells were therefore xenografted into control mice and mice in which ANGPTL4 was expressed by using in vivo DNA electrotransfer. Whereas primary tumors grew at a similar rate in both groups, 3LL cells metastasized less efficiently to the lungs of mice that expressed ANGPTL4. Fewer 3LL emboli were observed in primary tumors, suggesting that intravasation of 3LL cells was inhibited by ANGPTL4. Furthermore, melanoma B16F0 cells injected into the retro-orbital sinus also metastasized less efficiently in mice expressing ANGPTL4. Although B16F0 cells were observed in lung vessels, they rarely invaded the parenchyma, suggesting that ANGPTL4 affects extravasation. In addition, recombinant B16F0 cells that overexpress ANGPTL4 were generated, showing a lower capacity for in vitro migration, invasion, and adhesion than control cells. Expression of ANGPTL4 induced reorganization of the actin cytoskeleton through inhibition of actin stress fiber formation and vinculin localization at focal contacts. Together, these results show that ANGPTL4, through its action on both vascular and tumor compartments, prevents the metastatic process by inhibiting vascular activity as well as tumor cell motility and invasiveness. PMID:17130448

Galaup, Ariane; Cazes, Aurelie; Le Jan, Sebastien; Philippe, Josette; Connault, Elisabeth; Le Coz, Emmanuelle; Mekid, Halima; Mir, Lluis M.; Opolon, Paule; Corvol, Pierre; Monnot, Catherine; Germain, Stephane

2006-01-01

95

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

96

Evaluation of blood pressure control using a new arterial stiffness parameter, cardio-ankle vascular index (CAVI).  

PubMed

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

2013-02-01

97

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

98

Vascular endothelial growth factor and basic fibroblast growth factor present in Kaposi's sarcoma (KS) are induced by inflammatory cytokines and synergize to promote vascular permeability and KS lesion development.  

PubMed Central

All forms of Kaposi's sarcoma (KS) are characterized by spindle cell proliferation, angiogenesis, inflammatory cell infiltration, and edema. We have previously reported that spindle cells of primary KS lesions and KS-derived spindle cell cultures express high levels of basic fibroblast growth factor (bFGF), which is promoted by the inflammatory cytokines identified in these lesions. These cytokines, namely, tumor necrosis factor, interleukin-1, and interferon-gamma, induce production and release of bFGF, which stimulates angiogenesis and spindle cell growth in an autocrine fashion. Here we show that both AIDS-KS and classical KS lesions co-express vascular endothelial growth factor (VEGF) and bFGF. VEGF production by KS cells is promoted synergistically by inflammatory cytokines present in conditioned media from activated T cells and in KS lesions. KS cells show synthesis of VEGF isoforms that are mitogenic to endothelial cells but not to KS spindle cells, suggesting a prevailing paracrine effect of this cytokine. This may be due to the level of expression of the flt-1-VEGF receptor that is down-regulated in KS cells as compared with endothelial cells. KS-derived bFGF and VEGF synergize in inducing endothelial cell growth as shown by studies using both neutralizing antibodies and antisense oligodeoxynucleotides directed against these cytokines. In addition, VEGF and bFGF synergize to induce angiogenic KS-like lesions in nude mice and vascular permeability and edema in guinea pigs. These results indicate that inflammatory cytokines present in KS lesions stimulate the production of bFGF and VEGF, which, in turn, cooperate to induce angiogenesis, edema, and KS lesion formation. Images Figure 1 Figure 3 PMID:9626048

Samaniego, F.; Markham, P. D.; Gendelman, R.; Watanabe, Y.; Kao, V.; Kowalski, K.; Sonnabend, J. A.; Pintus, A.; Gallo, R. C.; Ensoli, B.

1998-01-01

99

Relation between aortic valve sclerosis and ankle-brachial index in participants clinically free of atherosclerotic vascular disease.  

PubMed

Most patients with peripheral arterial disease (PAD) are asymptomatic and have similar vascular morbidity and mortality with patients with symptomatic PAD. Despite being a very highly prevalent disease, physicians underdiagnose and undertreat PAD. A total of 100 participants with aortic valve sclerosis (AVS) and 100 participants without AVS and age-, gender-, and cardiovascular risk factor-matched participants were enrolled. Ankle-brachial index (ABI) and AVS were evaluated by handheld Doppler device and echocardiography, respectively. There was significantly lower ABI in participants with AVS compared with those without AVS (1.04 ± 0.14 v 1.11 ± 0.07, P = .001). There was a negative correlation between ABI and AVS (r = -.29, P < .001). Linear regression analysis demonstrated an independent association between ABI and AVS (95% confidence interval [CI]: -0.91 to -0.27, P < .001) and ?-blocker use (95% CI: -0.96 to -0.02, P: .04). Our findings confirm an association between AVS and PAD that may be attributed to shared vascular risk factors. PMID:23267238

Korkmaz, Levent; A?aç, Mustafa Tar?k; Bektas, Huseyin; Varol, Mustafa Oguz; Erkan, Hakan; Acar, Zeydin; Kurt, Devrim; Çelik, ?ükrü

2013-07-01

100

Relationship between cardio-ankle vascular index (CAVI) and coronary artery calcification (CAC) in patients with type 2 diabetes mellitus.  

PubMed

Early detection of atherosclerosis is important for patients with type 2 diabetes mellitus because cardiovascular disease (CVD) is a main cause of death in these people. In this study, we investigated the relationship between an arterial stiffness parameter called cardio-ankle vascular index (CAVI) and coronary artery calcification (CAC). We performed a cross-sectional study in 371 type 2 diabetic patients with clinical suspicion of coronary heart disease (CHD). We evaluated the relationships between CAVI and CAC score determined by multislice computed tomography as well as major cardiovascular risk factors, including age, body mass index, hemoglobinA1c and the Framingham CHD risk score. CAVI was correlated with age (r = 0.301, p < 0.0001), uric acid (r = 0.236, p < 0.0001), estimated glomerular filtration rate (r = -0.145, p = 0.0166), CHD risk score (r = 0.327, p < 0.0001) and log (CAC + 1) (r = 0.303, p < 0.0001). The area under the receiver operating characteristic curve for CAVI was higher than that of CHD risk score in predicting CAC >0, CAC >100, CAC >400, or CAC >1000. CAVI is positively correlated with CAC, and is considered to be a useful method to detect CAC. PMID:21476051

Mineoka, Yusuke; Fukui, Michiaki; Tanaka, Muhei; Tomiyasu, Ki-ichiro; Akabame, Satoshi; Nakano, Koji; Yamazaki, Masahiro; Hasegawa, Goji; Oda, Yohei; Nakamura, Naoto

2012-03-01

101

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

102

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

E-print Network

atlantic climate (Paris Basin, France)5 Methods: Moss and vascular (herb, fern) plant species were in vascular communities. Opposite response of these two plant14 groups could be explained by opposite1 Opposite responses of vascular and moss communities to1 changes in humus form, as expressed

103

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

104

Estrogen regulates vascular endothelial growth/permeability factor expression in 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors.  

PubMed

Vascular endothelial growth/permeability factor (VEG/PF) is expressed in some normal tissues and at high levels in a wide range of tumors. This growth factor is believed to be a key mediator of angiogenesis. Recent reports have shown that VEG/PF mRNA in the normal rat uterus is stimulated by estradiol (E2). In this study, we investigated the expression of VEG/PF in the mammary gland and 7,12-dimethylbenz(a)anthracene (DMBA)-induced, hormone-dependent mammary tumor of the rat model, and also whether VEG/PF is regulated by E2. VEG/PF mRNA from tumor extracts was amplified by RT-PCR with VEG/PF primers and generated two main products which corresponded in size to those expected for VEG/PF 164 and 120. In some cases, a third product corresponding in size to that expected for VEG/PF 188 was also generated. No such PCR products were generated from equal amount of RNA from normal mammary tissue, rat brain, or liver. Using immunocytochemistry, VEG/PF expression was detected in the epithelial cells of the tumors. We developed an ELISA assay to measure VEG/PF protein concentrations and found a 4-fold difference between normal mammary glands (1.3 +/- 0.11 ng/mg protein) and tumors (4.44 +/- 0.66) (P < 0.01). E2 treatment (5 microg/rat, s.c.) of rats 24 h after ovariectomy, greatly enhanced the expression of RT-PCR products in tumors within 2 h, which reached a maximum at 6-8 h but declined by 48 h. VEG/PF concentrations were also increased 8-12 h after E2 injection. When rats were given two injections of aromatase inhibitor 4-hydroxyandrostenedione (4-OHA 10 mg/rat s.c.) 24 h apart, to reduce estrogen concentrations, a low level of RT-PCR products was maintained for at least 96 h. After a single injection of 4-OHA, RT-PCR products remained low until 36 h when an increase occurred corresponding with a rise in plasma E2 levels. Injection of E2 2 h after 4-OHA treatment, caused a rise in RT-PCR products in 6-8 h. However, there was no significant change in VEG/PF concentrations. An increase in VEG/PF protein concentrations followed the increase in mRNA levels by 4-6 h. Thus, it appears that E2 causes a rapid induction of VEG/PF expression in mammary tumors that is similar to that observed in the normal uterus. These findings suggest that one mechanism by which estrogen acts as a mammary tumor promotor is by stimulating VEG/PF, leading to increased tumor angiogenesis and/or permeability of the microvessels to allow tumor cell migration. PMID:8940388

Nakamura, J; Savinov, A; Lu, Q; Brodie, A

1996-12-01

105

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

106

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

PubMed

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. PMID:23487181

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

2013-03-01

107

Pioglitazone improves the cardio-ankle vascular index in patients with type 2 diabetes mellitus treated with metformin  

PubMed Central

Background Type 2 diabetes is known to be associated with elevated cardiovascular mortality. Pioglitazone improves blood pressure (BP) and pulse wave velocity (PWV), which is an arterial stiffness parameter. Arterial stiffness is closely associated with cardiovascular disease. However, PWV is correlated with BP. The cardio-ankle vascular index (CAVI) reflects arterial stiffness independent of BP. Pioglitazone improves PWV but reduces blood pressure. The aim of this study was to re-evaluate the effect of pioglitazone on arterial stiffness with CAVI. Methods Sixty patients with type 2 diabetes mellitus and already on 500 mg/day of metformin received add-on therapy of pioglitazone 15 mg/day or glimepiride 1 mg/day for 6 months, during which time changes in their metabolic parameters and CAVI were observed. Results After 6 months of treatment, both pioglitazone (n=30) and glimepiride (n=30) improved fasting blood glucose and glycated hemoglobin. The changes in fasting blood glucose and glycated hemoglobin between the two groups were greater in the pioglitazone group. Systolic and diastolic BP was decreased in both groups, with no significant between-group differences. Only pioglitazone increased serum adiponectin levels, and the change in adiponectin between the pioglitazone and glimepiride groups was significantly different. CAVI was decreased significantly by pioglitazone but remained unchanged after treatment with glimepiride. The change in CAVI between the two groups was significantly different. Conclusion These results suggest that pioglitazone improves CAVI, a BP-independent arterial stiffness parameter, in patients with type 2 diabetes mellitus treated with metformin. PMID:25092992

Ohira, Masahiro; Yamaguchi, Takashi; Saiki, Atsuhito; Ban, Noriko; Kawana, Hidetoshi; Nagumo, Ayako; Murano, Takeyoshi; Shirai, Kohji; Tatsuno, Ichiro

2014-01-01

108

A cutoff point for arterial stiffness using the cardio-ankle vascular index based on carotid arteriosclerosis.  

PubMed

The cardio-ankle vascular index (CAVI) has been widely accepted as a good indicator of arteriosclerosis. However, the lack of a reliable diagnostic criterion for CAVI hampers the proper clinical screening for arteriosclerosis using CAVI and impedes the prompt treatment of cardiovascular disease (CVD). There is an urgent need to determine a criterion for CAVI in arteriosclerosis prevention. We conducted a cross-sectional study to determine this criterion based on receiver operating characteristic (ROC) analyses in a Chinese population consisting of 328 participants. CAVI was measured in duplicate, and carotid ultrasound detection was performed in a quiet environment by well-trained physicians. After multivariate adjustment, CAVI was positively associated with the risk of carotid arteriosclerosis. Compared with participants in the lowest tertile of CAVI (5.15-7.40), those in the medium (7.41-8.65) and highest (8.66-13.60) tertiles had odds ratios (95% confidence interval) of 2.2 (1.0, 4.9) and 4.4 (1.5, 13.3), respectively, for developing carotid arteriosclerosis (P trend=0.007). The areas under the ROC curve (AUC) of the male, female and pooled populations were 0.789, 0.897 and 0.856, respectively. The cutoff point of CAVI?8.0 resulted in the largest sensitivity and specificity. Furthermore, CAVI and age acted synergistically to increase the risk of carotid arteriosclerosis. CAVI?8.0 may be an optimal cutoff point for carotid arteriosclerosis prediction. The older population with higher CAVI scores had a higher risk of carotid arteriosclerosis. Additional large prospective studies are needed to confirm our findings. PMID:23324866

Hu, Huaqing; Cui, Huan; Han, Weixing; Ye, Liangping; Qiu, Wenting; Yang, Hui; Zhang, Chuanwu; Guo, Xiaojuan; Mao, Guangyun

2013-04-01

109

Sign choice for the index of refraction for arbitrary complex values of permittivity and permeability: Formal analysis  

NASA Astrophysics Data System (ADS)

It is shown that for an isotropic homogenous material region the expression for characteristic impedance Z =?c/n is more general than the usual expression Z =?? /? . This alternative expression together with the condition Re(Z) ? 0 uniquely determines the sign of the index of refraction n =±c??? for all values of ? and ?. Thus, the celebrated Veselago's argument that n < 0 for real negative values of ? and ? is rigorously generalized. A discussion of physically realizable complex material parameters ensues by considering the prescribed sign choice of n together with energy conservation.

Wilson, Gregory L.; Latypov, Damir M.

2014-06-01

110

Serum Osteoprotegerin is Associated with Arterial Stiffness Assessed According to the Cardio-ankle Vascular Index in Hypertensive Patients.  

PubMed

Aim: Arterial stiffness is recognized to be an independent risk factor for cardiovascular morbidity and mortality. Recent studies have found that osteoprotegerin (OPG) is associated with increased pulse wave velocity and may reflect endothelial dysfunction. The aim of this study was to evaluate the relationship between the serum OPG level and arterial stiffness in hypertensive patients using the cardio-ankle vascular index (CAVI). Methods: Fasting blood samples were obtained from 115 hypertensive patients and 52 healthy participants. The CAVI value was derived using the waveform device (CAVI-VaSera VS-1000). The serum OPG levels were measured using a commercially available enzyme-linked immunosorbent assay. A CAVI value of ?9 defined the high arterial stiffness group. Results: Sixty-five hypertensive patients (56.5%) were included in the high arterial stiffness group. Diabetes (p=0.032), smoking (p=0.044), age (p?0.001), systolic blood pressure (p=0.001), diastolic blood pressure (p=0.024), pulse pressure (p=0.046) and the creatinine (p=0.013) and serum OPG (p?0.001) levels were higher in the high arterial stiffness group than in the low arterial stiffness group, while the glomerular filtration rate (p=0.003) was lower in the high arterial stiffness group than in the low arterial stiffness group among the hypertensive patients. The results of the Spearman's rank correlation coefficient test also indicated a strong positive correlation between the OPG and CAVI values (r=0.484, p?0.001) in the hypertensive patients. In addition, a multivariate logistic regression analysis showed that age (odds ratio: 1.136, 95% confidence interval (CI): 1.053-1.225, p=0.001), diastolic blood pressure (odds ratio: 1.108, 95% CI: 1.035-1.187, p=0.003) and the logarithmically transformed OPG level (log-OPG; odds ratio: 3.740, 95% CI: 1.136-12.318, p=0.030) were independent predictors of arterial stiffness in the hypertensive patients. Conclusions: The serum OPG level is positively associated with arterial stiffness in hypertensive patients. PMID:25318352

Lee, Chung-Jen; Wang, Ji-Hung; Chen, Mei-Ling; Yang, Chiu-Fen; Chen, Yu-Chih; Hsu, Bang-Gee

2014-10-15

111

Influenza A virus infection of vascular endothelial cells induces GSK-3?-mediated ?-catenin degradation in adherens junctions, with a resultant increase in membrane permeability.  

PubMed

Multiorgan failure with vascular hyperpermeability is the final outcome in the progression of seasonal influenza virus pneumonia and influenza-associated encephalopathy, and it is also common in infection with highly pathogenic avian influenza virus. However, the precise molecular mechanism by which influenza virus infection causes vascular endothelial cell hyperpermeability remains poorly defined. We investigated the mechanisms of hyperpermeability of human umbilical vein endothelial cells infected with influenza A virus (IAV)/Puerto Rico/8/34 (PR8) (H1N1). The levels of ?-catenin, a key regulatory component of the vascular endothelial-cadherin cell adhesion complex, were markedly decreased during infection for 28 h, with increments of vascular hyperpermeability measured by transendothelial electrical resistance. Lactacystin (at 2 ?M), a proteasome inhibitor, inhibited the decrease in ?-catenin levels. Since the N-terminal phosphorylation of ?-catenin by glycogen synthase kinase (GSK)-3? is the initiation step of proteasome-dependent degradation, we examined the effects of GSK-3? suppression by RNA interference in endothelial cells. IAV-infection-induced ?-catenin degradation was significantly inhibited in GSK-3?-knockdown cells, and transfection of cells with recombinant ?-catenin significantly suppressed IAV-induced hyperpermeability. These findings suggest that IAV infection induces GSK-3?-mediated ?-catenin degradation in the adherens junctional complexes and induces vascular hyperpermeability. The in vitro findings of ?-catenin degradation and activation of GSK-3? after IAV infection were confirmed in lungs of mice infected with IAV PR8 during the course of infection from day 0 to day 6. These results suggest that GSK-3?-mediated ?-catenin degradation in adherens junctions is one of the key mechanisms of vascular hyperpermeability in severe influenza. PMID:25385175

Hiyoshi, M; Indalao, I L; Yano, M; Yamane, K; Takahashi, E; Kido, H

2015-01-01

112

The Semaphorin 4D- Plexin-B1- RhoA signaling axis recruits pericytes and regulates vascular permeability through endothelial production of PDGF-B and ANGPTL4  

PubMed Central

Semaphorin 4D (SEMA4D) is a member of a family of transmembrane and secreted proteins that have been shown to act through its receptor Plexin-B1 to regulate axon growth cone guidance, lymphocyte activation, and bone density. SEMA4D is also overexpressed by some malignancies and plays a role in tumor-induced angiogenesis similar to vascular endothelial growth factor (VEGF), a protein that has been targeted as part of some cancer therapies. In an attempt to examine the different effects on tumor growth and vascularity for these two pro-angiogenic factors, we previously noted that while inhibition of both VEGF and SEMA4D restricted tumor vascularity and size, vessels forming under conditions of VEGF blockade retained their association with pericytes while those arising in a background of SEMA4D/ Plexin-B1 deficiency did not, an intriguing finding considering that alteration in pericyte association with endothelial cells is an emerging aspect of anti-angiogenic intervention in the treatment of cancer. Here we show through array analysis, immunoblots, migration and co-culture assays and VE-cadherin immunohistochemistry that SEMA4D production by head and neck carcinoma tumor cells induces expression of platelet-derived growth factor-B (PDGF-B) and angiopoietin-like protein 4 (ANGPTL4) from endothelial cells in a Plexin-B1/ Rho-dependent manner, thereby influencing proliferation and differentiation of pericytes and vascular permeability, whereas VEGF lacks these effects. These results partly explain the differences observed between SEMA4D and VEGF in pathological angiogenesis and suggest that targeting SEMA4D function along with VEGF could represent a novel anti-angiogenic therapeutic strategy for the treatment of solid tumors. PMID:24114199

Zhou, Hua; Yang, Ying-Hua; Basile, John R.

2013-01-01

113

AG013736, a novel inhibitor of VEGF receptor tyrosine kinases, inhibits breast cancer growth and decreases vascular permeability as detected by dynamic contrast-enhanced magnetic resonance imaging  

Microsoft Academic Search

Dynamic contrast-enhanced MRI (DCE-MRI) was used to noninvasively evaluate the effects of AG-03736, a novel inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinases, on tumor microvasculature in a breast cancer model. First, a dose response study was undertaken to determine the responsiveness of the BT474 human breast cancer xenograft to AG-013736. Then, DCE-MRI was used to study the

Lisa J. Wilmes; Maria G. Pallavicini; Lisa M. Fleming; Jessica Gibbs; Donghui Wang; Ka-Loh Li; Savannah C. Partridge; Roland G. Henry; David R. Shalinsky; Dana Hu-Lowe; John W. Park; Teresa M. McShane; Ying Lu; Robert C. Brasch; Nola M. Hylton

2007-01-01

114

Activation of Matrix-Metalloproteinase-2 and Membrane-Type-1-Matrix-Metalloproteinase in Endothelial Cells and Induction of Vascular Permeability In Vivo by Human Immunodeficiency Virus-1 Tat Protein and Basic Fibroblast Growth Factor  

PubMed Central

Previous studies indicated that the Tat protein of human immunodeficiency virus type-1 (HIV-1) is a progression factor for Kaposi's sarcoma (KS). Specifically, extracellular Tat cooperates with basic fibroblast growth factor (bFGF) in promoting KS and endothelial cell growth and locomotion and in inducing KS-like lesions in vivo. Here we show that Tat and bFGF combined increase matrix-metalloproteinase-2 (MMP-2) secretion and activation in endothelial cells in an additive/synergistic manner. These effects are due to the activation of the membrane-type-1-matrix-metalloproteinase and to the induction of the membrane-bound tissue inhibitor of metalloproteinase-2 (TIMP-2) by Tat and bFGF combined, but also to Tat-mediated inhibition of both basal or bFGF-induced TIMP-1 and -2 secretion. Consistent with this, Tat and bFGF promote vascular permeability and edema in vivo that are blocked by a synthetic MMP inhibitor. Finally, high MMP-2 expression is detected in acquired immunodeficiency virus syndrome (AIDS)-KS lesions, and increased levels of MMP-2 are found in plasma from patients with AIDS-KS compared with HIV-uninfected individuals with classic KS, indicating that these mechanisms are operative in AIDS-KS. This suggests a novel pathway by which Tat can increase KS aggressiveness or induce vasculopathy in the setting of HIV-1 infection. PMID:11598182

Toschi, Elena; Barillari, Giovanni; Sgadari, Cecilia; Bacigalupo, Ilaria; Cereseto, Anna; Carlei, Davide; Palladino, Clelia; Zietz, Christian; Leone, Patrizia; Stürzl, Michael; Buttò, Stefano; Cafaro, Aurelio; Monini, Paolo; Ensoli, Barbara

2001-01-01

115

Vascular Endothelial Growth Factor-C, a Potential Paracrine Regulator of Glomerular Permeability, Increases Glomerular Endothelial Cell Monolayer Integrity and Intracellular Calcium  

PubMed Central

We have previously reported expression of vascular endothelial growth factor (VEGF)-A and -C in glomerular podocytes and actions of VEGF-A on glomerular endothelial cells (GEnC) that express VEGF receptor-2 (VEGFR-2). Here we define VEGFR-3 expression in GEnC and investigate the effects of the ligand VEGF-C. Renal cortex and cultured GEnC were examined by microscopy, and both cell and glomerular lysates were assessed by Western blotting. VEGF-C effects on trans-endothelial electrical resistance and albumin flux across GEnC monolayers were measured. The effects of VEGF-C156S, a VEGFR-3-specific agonist, and VEGF-A were also studied. VEGF-C effects on intracellular calcium ([Ca2+]i) were measured using a fluorescence technique, receptor phosphorylation was examined by immunoprecipitation assays, and phosphorylation of myosin light chain-2 and VE-cadherin was assessed by blotting with phospho-specific antibodies. GEnC expressed VEGFR-3 in tissue sections and culture, and VEGF-C increased trans-endothelial electrical resistance in a dose-dependent manner with a maximal effect at 120 minutes of 6.8 ? whereas VEGF-C156S had no effect. VEGF-C reduced labeled albumin flux by 32.8%. VEGF-C and VEGF-A increased [Ca2+]i by 15% and 39%, respectively. VEGF-C phosphorylated VEGFR-2 but not VEGFR-3, myosin light chain-2, or VE-cadherin. VEGF-C increased GEnC monolayer integrity and increased [Ca2+]i, which may be related to VEGF-C-S particular receptor binding and phosphorylation induction characteristics. These observations suggest that podocytes direct GEnC behavior through both VEGF-C and VEGF-A. PMID:18772335

Foster, Rebecca R.; Slater, Sadie C.; Seckley, Jaqualine; Kerjaschki, Dontscho; Bates, David O.; Mathieson, Peter W.; Satchell, Simon C.

2008-01-01

116

Vascular Hyperpermeability and Aging  

PubMed Central

Vascular hyperpermeability, the excessive leakage of fluid and proteins from blood vessels to the interstitial space, commonly occurs in traumatic and ischemic injuries. This hyperpermeability causes tissue vasogenic edema, which often leads to multiple organ failure resulting in patient death. Vascular hyperpermeability occurs most readily in small blood vessels as their more delicate physical constitution makes them an easy target for barrier dysfunction. A single layer of endothelial cells, linked to one another by cell adhesion molecules, covers the interior surface of each blood vessel. The cell adhesion molecules play a key role in maintaining barrier functions like the regulation of permeability. Aging is a major risk factor for microvascular dysfunction and hyperpermeability. Apart from age-related remodeling of the vascular wall, endothelial barrier integrity and function declines with the advancement of age. Studies that address the physiological and molecular basis of vascular permeability regulation in aging are currently very limited. There have been many cellular and molecular mechanisms proposed to explain aging-related endothelial dysfunction but their true relationship to barrier dysfunction and hyperpermeability is not clearly known. Among the several mechanisms that promote vascular dysfunction and hyperpermeability, the following are considered major contributors: oxidative stress, inflammation, and the activation of apoptotic signaling pathways. In this review we highlighted (a) the physiological, cellular and molecular changes that occur in the vascular system as a product of aging; (b) the potential mechanisms by which aging leads to barrier dysfunction and vascular hyperpermeability in the peripheral and the blood-brain barrier; (c) the mechanisms by which the age-related increases in oxidative stress, inflammatory markers and apoptotic signaling etc. cause endothelial dysfunction and their relationship to hyperpermeability; and (d) the relationship between aging, vascular permeability and traumatic injuries. PMID:24729937

Oakley, Ryan; Tharakan, Binu

2014-01-01

117

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

118

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

119

The percentage flow-mediated dilation index: a large-sample investigation of its appropriateness, potential for bias and causal nexus in vascular medicine.  

PubMed

The percentage flow-mediated dilation index (FMD%) scales the increase in arterial diameter (Ddiff) as a constant proportion of baseline artery diameter (Dbase). We have demonstrated, albeit with small samples, that the scaling properties of FMD% can lead to biased inferences on endothelial dysfunction. Therefore, we aimed to investigate the underlying rationale and potential bias of FMD% using a selection of new examples from the large (n = 3499) and diverse Multi-Ethnic Study of Atherosclerosis (MESA). In this dataset, we found that smaller values of Ddiff are associated with larger values of Dbase, which contradicts the scaling properties of FMD%. Consequently, FMD% 'over-scales' and naturally generates an even stronger negative correlation between itself and Dbase. Using a data simulation, we show that this FMD%-Dbase correlation can be a statistical artefact due to inappropriate scaling. The new examples we present from MESA indicate that FMD% biases the differences in flow-mediated response between men and women, Framingham risk score categories, and diseased and healthy people. We demonstrate how FMD%, as an exposure for predicting cardiovascular disease, is confounded by its dependency on Dbase, which itself could be clinically important. This critical review, incorporating an allometric analysis of a large dataset, suggests that the FMD% index has a less-than-clear rationale, can itself generate the Dbase-dependency problem, provides biased estimates of differences in the flow-mediated response, complicates the interpretation of the flow-mediated protocol and clouds the causal pathway to vascular disease. These interpretative problems can be resolved by applying accepted allometric principles to the flow-mediated response. PMID:24172228

Atkinson, Greg; Batterham, Alan M

2013-12-01

120

Negative associations between arterial stiffness parameter evaluated by cardio-ankle vascular index and serum low-density lipoprotein cholesterol concentration in early-stage atherosclerosis.  

PubMed

The cardio-ankle vascular index (CAVI), calculated values from cardio-ankle pulse wave velocity and blood pressure, corresponds predominantly to the stiffness of the aorta and peripheral arteries of the lower limbs. However, the reported associations between CAVI and serum low-density lipoprotein cholesterol (LDL-C) levels remain inconsistent. A cross-sectional study of 1878 consecutive patients (mean age: 59.2 years) who underwent general health checkup showed a negative association between CAVI and serum LDL-C or non-high-density lipoprotein cholesterol (non-HDL-C) concentrations with age-adjusted correlation and multiple regression analysis. Using the similar analyses divided by the status of risk factors and degree of maximum carotid intima-media thickness (maxIMT), negative correlations between CAVI and LDL-C or non-HDL-C levels were observed only in nonrisk groups including nondiabetics patients or patients with maxIMT <1.0 mm, in those with expected low extent of advanced atherosclerotic lesions. In contrast, such a correlation was not found in each comparable risk-loaded group. PMID:24402322

Homma, Satoki; Kato, Kiyoe; Hayashi, Junichi; Yamamoto, Minoru

2015-02-01

121

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

122

3'-Deoxy-3'-[(18)F]-fluorothymidine ([(18)F]-FLT) transport in newly diagnosed glioma: correlation with nucleoside transporter expression, vascularization, and blood-brain barrier permeability.  

PubMed

3'-Deoxy-3'-[(18)F]-fluorothymidine ([(18)F]-FLT), a marker of cellular proliferation, has been used in positron emission tomography (PET) examination of gliomas. The aim of this study was to investigate whether the uptake of [(18)F]-FLT in glioma correlates with messenger RNA (mRNA) levels of the equilibrative nucleoside transporter 1 (ENT1), microvascular density (assessed by CD34 immunohistochemistry), and the blood-brain barrier (BBB) breakdown. A total of 21 patients with newly diagnosed glioma were examined with [(18)F]-FLT PET. Tumor lesions were identified as areas of focally increased [(18)F]-FLT uptake, exceeding that of surrounding normal tissue. Dynamic analysis of [(18)F]-FLT PET revealed correlations between the phosphorylation rate constant k 3 and ENT1 expression; however there was no correlation between the kinetic parameters and CD34 score. There was a good correlation between the gadolinium (Gd) enhancement score (evaluating BBB breakdown) and ENT1 expression, CD34 score, and Ki-67 index. This preliminary study suggests that ENT1 expression might not reflect accumulation of [(18)F]-FLT in vivo due to BBB permeability in glioma. PMID:23423309

Shinomiya, Aya; Miyake, Keisuke; Okada, Masaki; Nakamura, Takehiro; Kawai, Nobuyuki; Kushida, Yoshio; Haba, Reiji; Kudomi, Nobuyuki; Tokuda, Masaaki; Tamiya, Takashi

2013-10-01

123

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

124

Serial assessment of arterial stiffness by cardio-ankle vascular index for prediction of future cardiovascular events in patients with coronary artery disease.  

PubMed

Arterial stiffness is a significant predictor of cardiovascular disease (CVD), the risk of which is modified by medications for atherosclerotic risk factors and life-style changes. Cardio-ankle vascular index (CAVI) provides noninvasive, objective information on arterial stiffness, independent of blood pressure. This study aimed to investigate changes in CAVI after management of atherosclerotic risk factors, and the impact of these changes on future CVD outcomes in patients with coronary artery disease (CAD). The study consisted of 211 CAD patients (65 ± 10 years, 118 men) with impaired CAVI. CAVI examination was repeated 6 months later. Impaired CAVI was defined as greater than the mean plus 1 s.d. of the age- and gender-specific normal CAVI values, according to results obtained in 5188 healthy subjects. All patients were followed for > 1 year or until the occurrence of a CVD event. Of the 211 patients, CAVI improved in 106 (50%) patients after 6 months, but remained high in 105 (50%) patients. During follow-up (2.9 ± 1.0 years), CVD events occurred in 28 (13%) patients. Persistently impaired CAVI was an independent predictor of future CVD events (P = 0.01), independent of baseline CAVI. CVD outcomes were worse in patients with persistently impaired CAVI than in those with improved CAVI (P < 0.001). Among patients with a normalized CAVI after treatment (n = 22) only one suffered a CVD event. This study was the first to demonstrate that persistent impairment of arterial stiffness was an independent risk factor of future CVD events. Serial measurements of CAVI provide important prognostic information regarding patients with CAD in clinical practice. PMID:25007768

Otsuka, Kenichiro; Fukuda, Shota; Shimada, Kenei; Suzuki, Kenji; Nakanishi, Koki; Yoshiyama, Minoru; Yoshikawa, Junichi

2014-11-01

125

Midinfrared Resonant Magnetic Nanostructures Exhibiting a Negative Permeability  

Microsoft Academic Search

We experimentally demonstrate the first midinfrared (mid-IR) resonant magnetic nanostructures exhibiting a strong magnetic response corresponding to a negative permeability. This result is an important step toward the achievement of a negative refractive index in the IR. The possibility of extending negative permeability to higher frequencies is discussed; a structure with a negative effective permeability at a near-IR resonance frequency

Shuang Zhang; Wenjun Fan; B. K. Minhas; Andrew Frauenglass; K. J. Malloy; S. R. Brueck

2005-01-01

126

The role of vascular endothelial growth factor in pathological angiogenesis  

Microsoft Academic Search

Vascular endothelial growth factor (VEGF) is a diffusible endothelial cell-specific mitogen and angiogenic factor that can also increase vascular permeability. By alternative splicing of mRNA, VEGF may exist as one of four different isoforms that have similar biological activities but differ markedly in targeting and bioavailability. The VEGF receptors are specifically expressed in the cell surface of vascular endothelial cells.

Napoleone Ferrara

1995-01-01

127

Vascular Cures  

MedlinePLUS

... learn more about Vascular Cures' programs click here . 2015 Wylie Scholar Award Applications are now open for ... North America. Deadline to apply is March 31, 2015 . For more information, click here. @ 2014 Vascular Cures ...

128

Diabetes and Retinal Vascular Dysfunction  

PubMed Central

Diabetes predominantly affects the microvascular circulation of the retina resulting in a range of structural changes unique to this tissue. These changes ultimately lead to altered permeability, hyperproliferation of endothelial cells and edema, and abnormal vascularization of the retina with resulting loss of vision. Enhanced production of inflammatory mediators and oxidative stress are primary insults with significant contribution to the pathogenesis of diabetic retinopathy (DR). We have determined the identity of the retinal vascular cells affected by hyperglycemia, and have delineated the cell autonomous impact of high glucose on function of these cells. We discuss some of the high glucose specific changes in retinal vascular cells and their contribution to retinal vascular dysfunction. This knowledge provides novel insight into the molecular and cellular defects contributing to the development and progression of diabetic retinopathy, and will aid in the development of innovative, as well as target specific therapeutic approaches for prevention and treatment of DR.

Shin, Eui Seok; Sorenson, Christine M.; Sheibani, Nader

2014-01-01

129

Involvement of vascular endothelial growth factor in exercise induced bronchoconstriction in asthmatic patients  

PubMed Central

Background: There is evidence that the bronchial microcirculation has the potential to contribute to the pathophysiological mechanisms of exercise induced bronchoconstriction (EIB) in asthmatic subjects. Vascular endothelial growth factor (VEGF), which is highly expressed in asthmatic airways, increases vascular permeability. The relationship between VEGF levels in induced sputum and the severity of EIB in asthmatic subjects was studied. Methods: The concentration of VEGF in induced sputum was examined in 23 asthmatic subjects and 11 normal controls. The asthmatic subjects performed an exercise test and the % maximal fall in forced expiratory volume in 1 second (FEV1) was measured. Beclomethasone dipropionate (BDP) 400 µg twice daily was administered to the asthmatic subjects for 8 weeks and the exercise test and sputum induction were repeated. Results: The concentration of VEGF in induced sputum was significantly higher in asthmatic subjects than in normal controls. There was a significant correlation between the concentration of VEGF and the % maximal fall in FEV1 (r=0.826, p=0.0001) and between the concentration of VEGF and airway vascular permeability index (r=0.621, p=0.0037). After treatment with inhaled BDP there was a significant decrease in the concentration of VEGF in the asthmatic subjects (before treatment: 7051 (2361) pg/ml, after treatment: 4498 (2135) pg/ml, p<0.0001). The change in the concentration of VEGF was significantly correlated with the change in the % maximal fall in FEV1 (r=0.463, p=0.031). Conclusions: Excessive production of VEGF in asthmatic airways may contribute to the pathogenesis of EIB via increased airway vascular permeability. PMID:12324676

Kanazawa, H; Hirata, K; Yoshikawa, J

2002-01-01

130

EPA Permeable Surface Research  

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...

131

Permeability of shaly sands  

NASA Astrophysics Data System (ADS)

The permeability of a sand shale mixture is analyzed as a function of shale fraction and the permeability of the two end-members, i.e., the permeability of a clay-free sand and the permeability of a pure shale. First, we develop a model for the permeability of a clay-free sand as a function of the grain diameter, the porosity, and the electrical cementation exponent. We show that the Kozeny-Carman-type relation can be improved by using electrical parameters which separate pore throat from total porosity and effective from total hydraulic radius. The permeability of a pure shale is derived in a similar way but is strongly dependent on clay mineralogy. For the same porosity, there are 5 orders of magnitude of difference between the permeability of pure kaolinite and the permeability of pure smectite. The separate end-members' permeability models are combined by filling the sand pores progressively with shale and then dispersing the sand grains in shale. The permeability of sand shale mixtures is shown to have a minimum at the critical shale content at which shale just fills the sand pores. Pure shale has a slightly higher permeability. Permeability decreases sharply with shale content as the pores of a sand are filled. The permeability of sand shale mixtures thus has a very strong dependence on shale fraction, and available data confirm this distinctive shale-fraction dependence. In addition, there is agreement (within 1 order of magnitude) between the permeabilities predicted from our model and those measured over 11 orders of magnitude from literature sources. Finally, we apply our model to predict the permeabilities of shaly sand formations in the Gulf Coast. The predictions are compared to a data set of permeability determination made on side-wall cores. The agreement between the theoretical predictions and the experimental data is very good.

Revil, A.; Cathles, L. M.

1999-03-01

132

Vascular Diseases  

MedlinePLUS

... and block blood flow to the heart or brain. Weakened blood vessels can burst, causing bleeding inside ... and not smoking can help vascular disease. Other treatments include medicines and surgery.

133

Follicular fluid vascular endothelial growth factor concentrations are elevated in women of advanced reproductive age undergoing ovulation induction  

Microsoft Academic Search

Objective(s): To determine whether follicular fluid (FF) from women of advanced reproductive age had a relative deficiency of the angiogenic cytokine vascular endothelial growth factor\\/vascular permeability factor. Furthermore, we sought to determine whether luteinized granulosa cells secrete vascular endothelial growth factor\\/vascular permeability factor in response to hypoxia.Design: Retrospective cohort study.Setting: University teaching hospital.Patients: Women undergoing follicular aspiration after superovulation in

Chad I. Friedman; Douglas R. Danforth; Cristina Herbosa-Encarnacion; Laura Arbogast; Baha M. Alak; David B. Seifer

1997-01-01

134

Metoclopramide and renal vascular resistance.  

PubMed

We have studied the effect of i.v. metoclopramide on renal vascular resistance in nine healthy volunteers. Peak systolic and end-diastolic frequencies were measured using duplex Doppler ultrasound of a renal interlobar artery, before and after the administration of i.v. metoclopramide 10 mg, and the resistance index derived. There was no significant change in mean arterial pressure or resistance index following metoclopramide. PMID:1997046

Manara, A R; Bolsin, S; Monk, C R; Hartnell, G; Harris, R A

1991-01-01

135

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, Zoltán; Koch, Alisa E

2008-01-01

136

Permeability and relative permeability in rocks  

SciTech Connect

Important features of the topology of the pore space of rocks can be usefully quantified by analyzing digitized images of rock cross sections. One approach computes statistical correlation functions using modern image processing techniques. These correlation functions contain information about porosity, specific surface area, tortuosity, formation factor, and elastic constants, as well as the fluid permeability and relative permeability. The physical basis of this approach is discussed and examples of the results for various sandstones are presented. The analysis shows that Kozeny-Carman relations and Archie's empirical laws must be modified to account for finite percolation thresholds in order to avoid unphysical behavior in the calculated relative permeabilities. 33 refs., 4 figs., 1 tab.

Blair, S.C.; Berryman, J.G.

1990-10-01

137

Vascular Caliber  

Microsoft Academic Search

Many aspects of vascular caliber can be accounted for on the basis of interactions between the frictional drag generated by the stream, and the sensitivity of the endothelial cells to this force. When the drag force on endothelial cells is at its critical set-point, these lining cells are at rest with respect to factors that affect caliber. An increase in

Simon Rodbard

1975-01-01

138

Vascular Proliferation  

NSDL National Science Digital Library

This FlashTM animation depicts vascularization of the early germ disc. It is shown in the context of a transverse section through a trilaminar germ disc and yolk sac. Clicking shows the cardiogenic field developing into the heart tube, along with vasculogenesis of the major vessels. Clicking again shows angiogenesis of peripheral vessels throughout the developing embryo and yolk sac.

PhD Jack D Thatcher (West Virginia School of Osteopathic Medicine Structural Biology)

2009-11-20

139

Toxicity of Kidney Bean (Phaseolus vulgaris) in Rats: Changes in Intestinal Permeability  

Microsoft Academic Search

Rats fed on diets containing kidney bean showed increased intestinal permeability to intravenously injected 125I-labelled rat serum proteins after an intragastric challenge with bean proteins. The enhanced accumulation of radioactive serum proteins in the lumen and walls of the small intestine indicated increased vascular permeability. It is suggested that dietary lectins may, at least in part, be responsible for this

Fiona Greer; Arpad Pusztai

1985-01-01

140

[Vascular parkinsonism].  

PubMed

Critchley speculated that multiple vascular lesions of the basal ganglia must have an etiological connection to the symptoms of so-called vascular parkinsonism (VP), but without neuropathological confirmation. Some had doubts about its existence because of the lack of the pathologically confirmed case with adequate clinical correlation. At present, VP is characterized clinically by the short-stepped or frozen gait, lead-pipe rigidity, the symmetry of findings, absence of resting tremor, and negative response to levodopa in elderly patients with cerebrovascular lesions on CT/MRI. Pseudobulbar palsies, pyramidal tract findings, and/or multi-infarct dementia coexist in some of the cases. Most of clinically suspected VP patients have cerebral white matter lesions as well as basal ganglia lesions. PMID:9014431

Yamanouchi, H

1997-01-01

141

Effect of low shear stress on permeability and occludin expression in porcine artery endothelial cells  

Technology Transfer Automated Retrieval System (TEKTRAN)

INTRODUCTION: Although both fluid shear stress and mass transport of atherogenic substances into the vascular wall are known to be important factors in atherogenesis, there has been little research on the effect of shear stress on vascular permeability. Therefore, the effects of shear stress on the ...

142

Inflammatory cytokines in vascular dysfunction and vascular disease.  

PubMed

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-kappaB, and Smad signaling pathways leading to an inflammatory response involving cell adhesion, permeability and apoptosis. Cytokines also interact with mitochondria to increase 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 Ca(2+), 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

2009-09-15

143

Permeability of porour rhyolite  

NASA Astrophysics Data System (ADS)

The development of permeability in bubble-bearing magmas determines the efficiency of volatile escape during their ascent through volcanic conduits, which, in turn, controls their explosive potential. As permeability requires bubble connectivity, relationships between permeability and porosity in silicic magmas must be controlled by the formation, growth, deformation and coalescence of their constituent bubbles. Although permeability data on porous volcanic pyroclasts are limited, the database can be greatly extended by including data for ceramic and metallic foams1. Several studies indicate that a single number does not adequately describe the permeability of a foam because inertial effects, which predominate at high flow rates, cause deviations from Darcy's law. These studies suggest that permeability is best modeled using the Forschheimer equation to determine both the Darcy permeability (k1) and the non-Darcian (k2) permeability. Importantly, at the high porosities of ceramic foams (75-95%), both k1 and k2 are strongly dependent on pore size and geometry, suggesting that measurement of these parameters provides important information on foam structure. We determined both the connected porosity (by He-pycnometry) and the permeability (k1 and k2) of rhyolitic samples having a wide range in porosity (22-85%) and vesicle textures. In general, these data support previous observations of a power law relationship between connected porosity and Darcy permeability2. In detail, variations in k1 increase at higher porosities. Similarly, k2 generally increases in both mean and standard deviation with increasing porosity. Measurements made on three mutually perpendicular cores from individual pumice clasts suggest that some of the variability can be explained by anisotropy in the vesicle structure. By comparison with ceramic foams, we suggest that the remaining variability results from differences either in average vesicle size or, more likely, in the size of apertures connecting individual vesicles. This interpretation is supported by the observation that clasts with high porosities but unusually low k1 and k2 also have high percentages of isolated pores (>10%), indicating extensive vesiculation but limited bubble coalescence; such clasts seem to be characteristic of ignimbrite deposits. 1Innocentini MDM, Salvini VR, Pandolfelli VC, Coury JC (1999) The permeability of ceramic foams. Amer Ceram Soc Bull 79:78-94. 2Klug C, Cashman KV (1996) Permeability development in vesiculating magmas - implications for fragmentation. Bull. Volcanol.58:87-100; Klug C, Cashman KV, Bacon C (2002) Structure and physical characteristics of pumice from the climactic eruption of Mt. Mazama (Crater Lake), Oregon. Bull Volcanol 64:486-501

Cashman, K.; Rust, A.; Wright, H.; Roberge, J.

2003-04-01

144

ConcepTest: Permeability  

NSDL National Science Digital Library

Three similar containers were filled with flour, rice or Cheerios. If you were to pour water into each container, how would they rank in terms of permeability (from highest to lowest)? a. Flour, Rice, Cheerios b. ...

145

Resistin Increases Monolayer Permeability of Human Coronary Artery Endothelial Cells  

PubMed Central

Resistin has been linked to obesity, insulin resistance, atherosclerosis, and the development of cardiovascular disease. Nevertheless, the effects and the molecular mechanisms of resistin on endothelial permeability, a key event in the development of atherosclerosis, inflammation, and vascular disease, are largely unknown. In order to determine the effect of resistin on endothelial permeability, human coronary artery endothelial cells (HCAECs) were treated with clinically relevant concentrations of resistin and the endothelial permeability was measured using the Transwell system with a Texas-Red-labeled dextran tracer. The permeability of HCAEC monolayers treated with resistin (80 ng/mL) was 51% higher than the permeability of control monolayers (P<0.05). The mRNA levels of tight junction proteins zonula occludens-1 (ZO-1) and occludin in resistin-treated cells were 37% and 42% lower, respectively, than the corresponding levels in untreated cells. The protein levels of these molecules in resistin-treated cells were significantly reduced by 35% and 37%, respectively (P<0.05), as shown by flow cytometry and Western blot analysis. Superoxide dismutase (SOD) mimetic MnTBAP effectively blocked the resistin-mediated reduction of ZO-1 and occludin levels in HCAECs. In addition, superoxide anion production was increased from 21% (untreated cells) to 55% (cells treated with 40 ng/mL resistin), and 64% (resistin, 80 mg/mL) (P<0.05). The natural antioxidant Ginkgolide A effectively inhibited resistin-induced increase in permeability and the increase in superoxide anion production in HCAECs. Furthermore, resistin treatment significantly activated p38 MAPK, but not ERK1/2. Pretreatment of HCAECs with a p38 inhibitor effectively blocked resistin-induced permeability. These results provide new evidence that resistin may contribute to the vascular lesion formation via increasing endothelial permeability through the mechanism of oxidative stress and the activation of p38 MAPK. PMID:24386395

Jamaluddin, Md Saha; Yan, Shaoyu; Lü, Jianming; Liang, Zhengdong; Yao, Qizhi; Chen, Changyi

2013-01-01

146

[Impotence of vascular origin].  

PubMed

Between 1977 and 1986, 3,500 patients were examined for the symptom of impotence; 1,250 of them received multidisciplinary investigation permitting the diagnosis of a pure organic or mixed disorder in 85% of cases, including 62% of vascular disease subdivided into arterial (40%) and venous (22%). For 1,062 patients, 1 or several of the following therapies were used: intracavernous infusion of vasoactive drugs (N = 725), auto-injections (N = 235), vascular surgery (N = 357) and prostheses (N = 23). The diagnostic approach, formerly analytical and making use of multiple non-invasive methods, such as nocturnal erection plethysmography (NPT) and invasive methods (artificial erection, arteriography) have been transformed by the use of pharmacological tests associated with visual sexual stimulation (VSS) which enable, together with Doppler velocimetric examination, simple screening of vascular impotence based on the study of 4 parameters: penile pressure index (PPI) when less than 0.91 is always a sign of an arterial problem, the severity of which is directly proportional to the lowering of this index and the association with maintenance insufficiency; the initial intracavernous flow rate (IICF) depends overall on the maintenance flow and the state of erectile tissue, resulting from pharmacological stimulation by a low dose of papaverine (8 mg); penile rigidity attained by the combined action of pharmacological and visual sexual stimulation, reflecting the functional erectile capacity; the duration of the rigidity thus obtained on stoppage of VSS indicating the capacity for maintenance of erection. In the event of suspicion of an isolated venous leak or in association with arterial problems, it is the artificial erection with cavernosography, carried out after pharmacological stimulation, which enables the severity of the leak to be assessed. The following specific investigations are carried out to investigate a specific associated etiology: electromyogram for neurological disorders, hormone assay for endocrine disorders and psychological study using the MMPI questionnaire (Multiphasic Minnesota Personality Inventory). One can thus distinguish several groups of patients suffering from vascular impotence depending on the degree of arterial involvement: minor (PPI between 0.75 and 0.9), moderate (PPI between 0.65 and 0.75) and severe (PPI less than 0.65); depending on the degree of venous leaking: absent (MI less than 0.3 and/or MF less than 25 ml/min), minor (MI between 0.3 and 0.5 and MF between 30 and 50 ml/min), moderate (MI between 0.5 and 75 ml/min) and severe (MI greater than 0.75 and/or MF greater than 75 ml/mn).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2754346

Virag, R; Sussman, H; Shoukry, K; Floresco, J; Mazel, J P; Lévy, C; Saltiel, H

1989-01-01

147

Postnatal changes of vascular endothelial growth factor (VEGF) expression in the retinae of normal and hypertensive rats  

Microsoft Academic Search

Vascular endothelial growth factor (VEGF) has been shown to have potent mitotic activity specific to vascular endothelial cells and has been related to vascular permeability, angiogenesis and cell proliferation in both normal and pathological situations. The present study aimed at elucidating the spatio-temporal changes in the postnatal expression pattern of VEGF in the retinae of both normal and hypertensive rats.

W. Y. Chan; Rufina S. Y. Cheng; D. T. Yew

2000-01-01

148

Effect of Polycaprolactone Scaffold Permeability on Bone Regeneration In Vivo  

PubMed Central

Successful bone tissue engineering depends on the scaffold's ability to allow nutrient diffusion to and waste removal from the regeneration site, as well as provide an appropriate mechanical environment. Since bone is highly vascularized, scaffolds that provide greater mass transport may support increased bone regeneration. Permeability encompasses the salient features of three-dimensional porous scaffold architecture effects on scaffold mass transport. We hypothesized that higher permeability scaffolds will enhance bone regeneration for a given cell seeding density. We manufactured poly-?-caprolactone scaffolds, designed to have the same internal pore design and either a low permeability (0.688×10?7m4/N-s) or a high permeability (3.991×10?7m4/N-s), respectively. Scaffolds were seeded with bone morphogenic protein-7-transduced human gingival fibroblasts and implanted subcutaneously in immune-compromised mice for 4 and 8 weeks. Micro-CT evaluation showed better bone penetration into high permeability scaffolds, with blood vessel infiltration visible at 4 weeks. Compression testing showed that scaffold design had more influence on elastic modulus than time point did and that bone tissue infiltration increased the mechanical properties of the high permeability scaffolds at 8 weeks. These results suggest that for polycaprolactone, a more permeable scaffold with regular architecture is best for in vivo bone regeneration. This finding is an important step toward the end goal of optimizing a scaffold for bone tissue engineering. PMID:21395465

Mitsak, Anna G.; Kemppainen, Jessica M.; Harris, Matthew T.

2011-01-01

149

Understanding Pulmonary Vascular Disease  

MedlinePLUS

... ENews Home > Lung Disease > Pulmonary Vascular Disease Understanding Pulmonary Vascular Disease Pulmonary vascular disease is a category of disorders. ... in a person's pulmonary arteries gets dangerously high. Pulmonary Veno-occlusive Disease This is an extremely rare form of high ...

150

Permeability of crystalline rocks  

NASA Astrophysics Data System (ADS)

In contrast to most other petrophysical parameters, intrinsic permeability for any single rock type varies by the decade rather than by the factor (see, for example, Bear [1972]). Both the type of measurement and its characteristic scale (that is, the rock volume over which an individual permeability value is integrated) are responsible for this. Brace [1980, 1984] compiled permeabilities of sedimentary (porous) and crystalline (fractured) rocks and pointed out that both types of rock exhibit a “scale effect”: the larger the experiment's scale, or characteristic volume, the greater the permeability. One other transport parameter, dispersion length or dispersivity, which is closely related to permeability, behaves similarly. There are both data compilations for dispersivity documenting this scale effect [Beims, 1983; Gelhar et al., 1985] and theoretical studies (such as Neumann [1990]) discussing possible scaling rules. An interesting conclusion by Neumann [1990], which is in good agreement with Brace's results, is that "porous and fractured media appear to follow the same idealized scaling rule for both flow and transport, raising a question about the validity of many distinctions commonly drawn between such media."

Clauser, Christoph

151

Endothelial precursors in vascular repair.  

PubMed

The endothelium is an essential component of the cardiovascular system, playing a vital role in blood vessel formation, vascular homeostasis, permeability and the regulation of inflammation. The integrity of the endothelial monolayer is also critical in the prevention of atherogenesis and as such, restoration of the monolayer is essential following damage or cell death. Over the past decade, data has suggested that progenitor cells from different origins within the body are released into the circulation and contribute to re-endothelialisation. These cells, termed endothelial progenitor cells (EPCs), also gave rise to the theory of new vessel formation within adults (vasculogenesis) without proliferation and migration of mature endothelial cells (angiogenesis). As such, intense research has been carried out identifying how these cells may be mobilised and contribute to vascular repair, either encouraging vasculogenesis into regions of ischemia or the re-endothelialisation of vessels with a dysfunctional endothelium. However, classification and isolation procedures have been a major problem in this area of research and beneficial use for therapeutic application has been controversial. In the present review we focus on the role of EPCs in vascular repair. We also provide an update on EPC classification and discuss autologous stem cell-derived endothelial cell (EC) as a functional source for therapy. PMID:20184904

Kirton, John Paul; Xu, Qingbo

2010-05-01

152

The Ability of Permeability  

NSDL National Science Digital Library

In this activity (page 11 of the PDF), learners investigate how quickly water moves through various materials. They measure and compare the permeability of gravel, sand, and soil. Although this was created as a post-visit activity for a workshop about earth processes, it also makes an excellent stand alone activity.

Cosi

2009-01-01

153

Intestinal permeability: An overview  

Microsoft Academic Search

The noninvasive assessment of intestinal permeability in humans has a 20-year history. Because the tests are increasingly used in clinical practice and research and because there is much controversy, we reviewed the literature and outlined the potential and possible shortcomings of these procedures. Data was obtained from personal files and from a systemic search through MEDLINE and EMBASE. The principle

Ingvar Bjarnason; Andrew Macpherson; Daniel Hollander

1995-01-01

154

Vascular dysfunction in obesity and insulin resistance.  

PubMed

With the growing prevalence of obesity and impaired glycemic control, and the correlation between these conditions and an elevated predisposition for the development of vascular disease, research emphases are increasingly being targeted to the mechanistic bases and functional outcomes of these relationships. Given this, the current issue of Microcirculation, presents a series of reviews that summarize knowledge on an array of topics relevant to obesity, insulin resistance, and vascular dysfunction. The first chapters discuss altered patterns of blood flow regulation, vascular reactivity, microvascular density, and vascular wall mechanics. The second grouping details alterations to coronary, renal, and hepatic circulations and the implications of these effects for organ function. Additionally, one article presents knowledge and outlines future research directions for the study of endothelial permeability and barrier function within insulin resistance. The last group of articles discusses the effects of inflammation with obesity and insulin resistance on vascular function, and also details the role of perivascular adipose tissue in contributing to vascular dysfunction. The final review extends this general topic to the effects of the metabolic syndrome on microvascular dysfunction, wherein obesity and impaired glycemic control are contributing elements to a larger constellation of systemic pathologies. The authors hope that this Special Topics Issue will be informative for its readers and will provide a basis for future investigation into microvasculopathy in obesity and insulin-resistance. PMID:17613800

Frisbee, Jefferson C

2007-01-01

155

Vascular endothelial growth factor and placenta growth factor concentrations in Down's syndrome and control pregnancies  

Microsoft Academic Search

Vascular endothelial growth factor (VEGF) and placenta growth factor (PLGF) are considered to play important roles in angiogenesis and vascular permeability during placental development. Since trisomy 21 placentae show trophoblastic hypoplasia and hypovascularity, we investigated PLGF and VEGF synthesis in Down's syndrome pregnancies. Maternal serum was collected from 102 euploid and 24 trisomy 21 pregnancies between 15 and 20 weeks

F. Debieve; A. Moiset; K. Thomas; S. Pampfer; C. Hubinont

2001-01-01

156

[Permeability of the hemato-ophthalmic barrier in uveitis].  

PubMed

The results of examining the hematoophthalmic barrier permeability by radiometry and biotests with anterior chamber and vitreous humor are analyzed. Injection of the radiopharmaceutical into the vorticose veins provides the most effective pharmacokinetics, vs. suprachoroidal and subconjunctival injections. In toxis allergic uveitis the penetration of radiopharmaceuticals into the internal media of the eye (anterior chamber humor and vitreous body) is intensified, and dexason therapy of an inflammatory process in the vascular coating reduces this penetration. PMID:2368251

Pen'kov, M A; Saitov, M A; Nesterov, V G; Knigavko, V G

1990-01-01

157

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

158

Intestinal permeability in kwashiorkor  

PubMed Central

Accepted 16 September 1996? Intestinal permeability can be assessed non-invasively using the lactulose-rhamnose (L-R) test, which is a reliable measure of small intestinal integrity.?AIMS—To determine risk factors for abnormal intestinal permeability in kwashiorkor, and to measure changes in L-R ratios with inpatient rehabilitation.?DESIGN—A case-control study of 149 kwashiorkor cases and 45 hospital controls. The L-R test was adapted to study kwashiorkor in Malawi, with testing at weekly intervals during nutritional rehabilitation. Urine sugars were measured by thin layer chromatography in London.?RESULTS—The initial geometric mean L-R ratios (×100) (with 95% confidence interval) in kwashiorkor were 17.3 (15.0 to 19.8) compared with 7.0 (5.6 to 8.7) for controls. Normal ratios are <5, so the high ratios in controls indicate tropical enteropathy syndrome. Abnormal permeability in kwashiorkor was associated with death, oliguria, sepsis, diarrhoea, wasting and young age. Diarrhoea and death were associated with both decreased L-rhamnose absorption (diminished absorptive surface area) and increased lactulose permeation (impaired barrier function) whereas nutritional wasting affected only L-rhamnose absorption. Despite clinical recovery, mean L-R ratios improved little on treatment, with mean weekly ratios of 16.3 (14.0 to 19.0), 13.3 (11.1 to 15.9) and 14.4 (11.0 to 18.8).?CONCLUSION—Abnormal intestinal permeability in kwashiorkor correlates with disease severity, and improves only slowly with nutritional rehabilitation.?? PMID:9135265

Brewster, D; Manary, M; Menzies, I; O'Loughlin, E; Henry, R

1997-01-01

159

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

2011-07-01

160

Advances in vascular imaging.  

PubMed

Advances in vascular surgery have mirrored advances in diagnostic imaging. Indeed, the endovascular revolution has been made possible largely by advances in computed tomography, magnetic resonance imaging, and vascular ultrasound. As technology allows better noninvasive vascular diagnosis, conventional angiography, once the gold standard for the diagnosis of vascular disease, is now reserved largely for intervention. This article discusses the current state of vascular imaging. Specific emphasis is placed on the comparative clinical utility of different imaging modalities in the detection and management of vascular disease. PMID:17936471

Perry, Jason T; Statler, John D

2007-10-01

161

Impaired Vascular Reactivity in Patients with Chronic Kidney Disease  

Microsoft Academic Search

Background: Patients with chronic kidney disease (CKD) show increased cardiovascular morbidity. We hypothesized that vascular properties which can be routinely evaluated noninvasively are related to different stages of CKD and their clinical and biochemical characteristics. Methods: Arterial vascular properties were quantified by the reflective index using digital photoplethysmography in 260 patients with CKD. Patients were grouped according to estimated glomerular

Fabian Tetzner; Alexandra Scholze; Antje Wittstock; Walter Zidek; Martin Tepel

2008-01-01

162

Physics of negative refractive index materials  

Microsoft Academic Search

In the past few years, new developments in structured electromagnetic materials have given rise to negative refractive index materials which have both negative dielectric permittivity and negative magnetic permeability in some frequency ranges. The idea of a negative refractive index opens up new conceptual frontiers in photonics. One much-debated example is the concept of a perfect lens that enables imaging

S Anantha Ramakrishna

2005-01-01

163

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

164

Society for Vascular Medicine  

MedlinePLUS

... 31- Jan2. Updated! Patient Information Pages from Vascular Medicine December 2014 Carotid artery disease More info for ... Learn more. Trending Now: Hot Topics in Vascular Medicine Video Series! Fibromuscular Dysplasia (FMD) with Drs. Jeffrey ...

165

Porosity and Permeability  

NSDL National Science Digital Library

The students are exposed to a brief (approx. 5 minute) introduction/presentation on aquifers and groundwater including their geographical context, structure, and vocabulary. The students receive everyday materials with different properties: Styrofoam block, scrubbing pad, etc, and a dropper bottle filled with water. They are not initially told what to do, but instead asked what they are going to do. The idea is to use the dropper bottle to put water on the objects and notice if the water passes through or not? They are also encouraged to notice any physical features that may be responsible for these behaviors. Students typically won't talk to each other at first and won't know what to do. Asking them guided questions usually encourages conversation between the students. They can also be asked what other everyday objects could be used for this exercise. After they have explore everyday objects, they are introduced to a handsample of granite and a sandstone. Although they have not been exposed to rocks in lab, they can usually identify the granite right away, and the sandstone when about the size of the grains. They then will discuss the physical properties of the rocks and hypothesize what is more porous and permeable. They test this with the water dropper. Finally, as a class, we discuss that something that is porous and permeable like a sandstone makes a good aquifer, and where good aquifers are located.

Witherow, Rebecca

166

Use of diagnostic modalities for assessing upper extremity vascular pathology.  

PubMed

Vascular pathology of the upper extremity requires consideration of constitutional, anatomic, and functional factors. The medical history and physical examination are essential. The Allen test can be performed alongside a handheld Doppler for arterial mapping. Useful studies include digital-brachial index measurements, digital plethysmography, laser Doppler, and color ultrasounds. Three-phase bone scintigraphy still plays a role in the evaluation of vascularity after of frostbite injury. Angiogram remains the gold standard radiographic instrument to evaluate vascular pathology of the upper extremity, but computed tomography and magnetic resonance scans have an increasing role in diagnosis of vascular pathology. PMID:25455352

Grasu, Beatrice L; Jones, Christopher M; Murphy, Michael S

2015-02-01

167

Permeability of aqueous foams  

NASA Astrophysics Data System (ADS)

We perform forced-drainage experiments in aqueous foams and compare the results with data available in the literature. We show that all the data can be accurately compared together if the dimensionless permeability of the foam is plotted as a function of liquid fraction. Using this set of coordinates highlights the fact that a large part of the published experimental results corresponds to relatively wet foams ( \\varepsilon ˜ 0.1). Yet, most of the foam drainage models are based on geometrical considerations only valid for dry foams. We therefore discuss the range of validity of the different models in the literature and their comparison to experimental data. We propose extensions of these models considering the geometry of foam in the relatively wet-foam limit. We eventually show that if the foam geometry is correctly described, forced drainage experiments can be understood using a unique parameter -the Boussinesq number.

Lorenceau, E.; Louvet, N.; Rouyer, F.; Pitois, O.

2009-03-01

168

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.

169

Placental Permeability of Lead  

PubMed Central

The detection of lead in fetal tissues by chemical analysis has long been accepted as prima facie evidence for the permeability of the placenta to this nonessential trace metal. However, only a few investigations, all on lower mammalian species, have contributed any direct experimental data bearing on this physiological process. Recent radioactive tracer and radioautographic studies on rodents have shown that lead crosses the placental membranes rapidly and in significant amounts even at relatively low maternal blood levels. While it is not possible to extrapolate directly the results of these experiments to humans because of differences in placental structure and other factors, the results do serve as a warning of the possible hazard to the human embryo and fetus of even low levels of lead in the maternal system. PMID:4857497

Carpenter, Stanley J.

1974-01-01

170

Deep dorsal vein arterialization in vascular impotence.  

PubMed

33 patients underwent a penile deep dorsal vein arterialization (DDVA) (11 venous leak, 8 pure arteriogenic impotence, 14 mixed arterial and venous impotence). The mean follow-up was 12 months. Surgery was considered successful when the patients had permeable anastomosis and were able to achieve satisfactory erections resulting in normal intercourse. 92% of the patients with venous leak, 62.5% of those with arteriogenic impotence and 58% with mixed lesions had a successful results. Due to antithrombotic therapy, there was no graft occlusion. Glans hypervascularity occurred in 3 patients and was treated by arterial banding. The role of DDVA in vascular impotence and its functional mechanism are discussed. PMID:8307073

Sarramon, J P; Janssen, T; Rischmann, P; Bennis, S; Malavaud, B

1994-01-01

171

Relative Permeability of Fractured Rock  

E-print Network

SGP-TR-172 Relative Permeability of Fractured Rock Mark D. Habana June 2002 Financial support experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach permeability of a core is especially important in a fractured rock. The rock may change as asperities

Stanford University

172

Diffusion and Osmosis Selectively Permeable  

E-print Network

Diffusion and Osmosis #12;Selectively Permeable Some substances can pass through the membrane Dissolved molecules #12;Osmosis Diffusion of water molecules through a selectively-permeable membrane the solvent #12;Effects of Osmosis on Cells [water] = [solute] Low [water] outside cell High [water

Rose, Michael R.

173

Permeability within basaltic oceanic crust  

Microsoft Academic Search

Water-rock interactions within the seafloor are responsible for significant energy and solute fluxes between basaltic oceanic crust and the overlying ocean. Permeability is the primary hydrologic property control- ling the form, intensity, and duration of seafloor fluid circulation, but after several decades of characterizing shallow oceanic basement, we are still learning how permeability is created and distributed and how it

Andrew T. Fisher

1998-01-01

174

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, Rogério; Oliveira, Marcus F.; Bozza, Marcelo T.; Da Poian, Andrea T.; Weyrich, Andrew S.; Zimmerman, Guy A.

2013-01-01

175

Vascular tracers alter hemodynamics and airway pressure in anesthetized sheep  

SciTech Connect

The technique of vascular labeling was developed to mark sites of increased microvascular permeability. We used the vascular labeling technique in anesthetized sheep and found that hemodynamics and airway pressure were adversely affected by intraarterial infusions of two vascular tracers. Monastral blue (nine sheep) immediately caused systemic arterial hypotension, pulmonary arterial hypertension, and bronchoconstriction. All three physiological responses were partially blocked by a cyclooxygenase inhibitor (indomethacin) but not by an H1-antihistamine (chlorpheniramine). Colloidal gold (nine sheep) caused immediate, but less dramatic, pulmonary arterial hypertension which was not attenuated by the blocking agents. We conclude that these two vascular tracers caused detrimental physiological side effects in sheep at the usual doses used to label injured microvessels in other species.

Albertine, K.H.; Staub, N.C.

1986-11-01

176

Permeable Pavements, Green Roofs, and Cisterns  

E-print Network

Permeable Pavements, Green Roofs, and Cisterns Stormwater Treatment Practices for Low site planning and engineer- pavements, green roofs, and cisterns, are ing to reduce or prevent cooperating. #12;Permeable Pavements What are they? Permeable pavements provide alternatives to standard

Hunt, William F.

177

Effect of platelet activating factor on endothelial permeability to plasma macromolecules  

SciTech Connect

The effect of intrajugular administration of platelet activating factor (PAF-C16) on vascular permeability was examined in the guinea pig. To examine the loss of selective endothelial permeability, the extravasative effect of PAF was assessed by monitoring hemoconcentration and the plasma loss of /sup 125/I-albumin (6.7 nm), /sup 125/I-low density lipoproteins (22.0 nm) or /sup 125/I-very low density lipoproteins (62.1 nm). Extravasation was dose-dependent and began 1 min after PAF administration, continuing for 5-7 min. During extravasation, there was no evidence for selective plasma retention of any of the labeled plasma tracers, as measured by plasma radioactivity. These results suggest that PAF-induced extravasation is dose-dependent, with increases in vascular permeability sufficient to permit similar plasma efflux rates of albumin, low density lipoproteins and very low density lipoproteins.

Handley, D.A.; Arbeeny, C.M.; Lee, M.L.; Van Valen, R.G.; Saunders, R.N.

1984-12-01

178

Vascular anomalies in children.  

PubMed

The process of understanding and treating children with vascular anomalies has been hampered by confusing and occasionally incorrect terminology. The most important step when evaluating a maxillofacial vascular anomaly is to determine whether it is a tumor or a malformation. In most cases, this diagnosis can be made by history and physical examination. Selective radiographic imaging is helpful in differentiating vascular malformations or the extent of bony involvement and/or destruction. Children with vascular anomalies should be managed by an interdisciplinary team of trained providers who are committed to following, treating, and studying patients with these complex problems. PMID:22771277

Abramowicz, Shelly; Padwa, Bonnie L

2012-08-01

179

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

180

Pulmonary vascular dysfunction in ARDS  

PubMed Central

Acute respiratory distress syndrome (ARDS) is characterised by diffuse alveolar damage and is frequently complicated by pulmonary hypertension (PH). Multiple factors may contribute to the development of PH in this setting. In this review, we report the results of a systematic search of the available peer-reviewed literature for papers that measured indices of pulmonary haemodynamics in patients with ARDS and reported on mortality in the period 1977 to 2010. There were marked differences between studies, with some reporting strong associations between elevated pulmonary arterial pressure or elevated pulmonary vascular resistance and mortality, whereas others found no such association. In order to discuss the potential reasons for these discrepancies, we review the physiological concepts underlying the measurement of pulmonary haemodynamics and highlight key differences between the concepts of resistance in the pulmonary and systemic circulations. We consider the factors that influence pulmonary arterial pressure, both in normal lungs and in the presence of ARDS, including the important effects of mechanical ventilation. Pulmonary arterial pressure, pulmonary vascular resistance and transpulmonary gradient (TPG) depend not alone on the intrinsic properties of the pulmonary vascular bed but are also strongly influenced by cardiac output, airway pressures and lung volumes. The great variability in management strategies within and between studies means that no unified analysis of these papers was possible. Uniquely, Bull et al. (Am J Respir Crit Care Med 182:1123–1128, 2010) have recently reported that elevated pulmonary vascular resistance (PVR) and TPG were independently associated with increased mortality in ARDS, in a large trial with protocol-defined management strategies and using lung-protective ventilation. We then considered the existing literature to determine whether the relationship between PVR/TPG and outcome might be causal. Although we could identify potential mechanisms for such a link, the existing evidence does not allow firm conclusions to be drawn. Nonetheless, abnormally elevated PVR/TPG may provide a useful index of disease severity and progression. Further studies are required to understand the role and importance of pulmonary vascular dysfunction in ARDS in the era of lung-protective ventilation.

2014-01-01

181

Small intestinal permeability in older adults  

PubMed Central

Abstract It is not yet clear whether intestinal mucosal permeability changes with advancing age in humans. This question is of high importance for drug and nutrition approaches for older adults. Our main objective was to answer the question if small intestinal barrier integrity deteriorates with healthy aging. We conducted a cross?sectional study including the pooled data of 215 nonsmoking healthy adults (93 female/122 male), 84 of whom were aged between 60 and 82 years. After a 12?h fast, all participants ingested 10 g of lactulose and 5 g of mannitol. Urine was collected for 5 h afterwards and analyzed for test sugars. The permeability index (PI = lactulose/mannitol) was used to assess small intestinal permeability. Low?grade inflammation defined by high?sensitivity C?reactive protein ?1 mL/L and kidney function (estimated glomerular filtration rate) were determined in the older age group. The PI was similar in older compared to younger adults (P =0.887). However, the urinary recovery of lactulose and mannitol was lower in the older adults and this change was neither associated with urinary volume nor glomerular filtration rate. The PI was not significantly correlated with low?grade inflammation or presence of noninsulin?dependent type 2 diabetes. However, it significantly deteriorated in the copresence of both conditions compared to low?grade inflammation alone (P =0.043) or type 2 diabetes alone (P =0.015). Small intestinal mucosal barrier does not deteriorate with age per se. But low?grade inflammation coupled with minor disease challenges, such as type 2 diabetes, can compromise the small intestinal barrier. PMID:24771689

Valentini, Luzia; Ramminger, Sara; Haas, Verena; Postrach, Elisa; Werich, Martina; Fischer, André; Koller, Michael; Swidsinski, Alexander; Bereswill, Stefan; Lochs, Herbert; Schulzke, Jörg?Dieter

2014-01-01

182

Permeabilities of Subduction Zone Sediments  

NASA Astrophysics Data System (ADS)

Permeabilities of subseafloor sediments control fluid expulsion from sediments as they are subducted or accreted and thus, compaction state, fluid overpressures, and deformation. We compare results from Integrated Ocean Drilling Program samples to compare to previously-developed permeability-porosity relationships for subduction zone sediments. Hemipelagic clay samples obtained from the incoming plate Kumano transect of the Nankai Trough (NanTroSEIZE) yield slightly lower permeability for a given porosity than previously reported results from Nankai Trough's Muroto transect and are lower than clay-rich sediments from the upper plate of CRISP offshore the Osa Peninsula of Costa Rica (CRISP). Samples from the Pacific Equatorial Transect (PEAT) and the South Pacific Gyre provide further insight to permeability behavior of sediments deposited in the Pacific basin. South Pacific Gyre sediments consist of slowly deposited pelagic clay with little biogenic or coarse clastic input. Measured permeabilities for given porosities are consistently lower than values reported for clay-rich sediments of Nankai and Costa Rica. PEAT samples comprise biogenic oozes and yield inconsistent results, with some of the highest permeabilities (10-14 m2) as well as some results similar to clay-rich sediments.

Screaton, E.; Gamage, K. R.; Daigle, H.; Harris, R. N.

2013-12-01

183

Hormonal Regulation of Nuclear Permeability*?  

PubMed Central

Transport into the nucleus is critical for regulation of gene transcription and other intranuclear events. Passage of molecules into the nucleus depends in part upon their size and the presence of appropriate targeting sequences. However, little is known about the effects of hormones or their second messengers on transport across the nuclear envelope. We used localized, two-photon activation of a photoactivatable green fluorescent protein to investigate whether hormones, via their second messengers, could alter nuclear permeability. Vasopressin other hormones that increase cytosolic Ca2+ and activate protein kinase C increased permeability across the nuclear membrane of SKHep1 liver cells in a rapid unidirectional manner. An increase in cytosolic Ca2+ was both necessary and sufficient for this process. Furthermore, localized photorelease of caged Ca2+ near the nuclear envelope resulted in a local increase in nuclear permeability. Neither activation nor inhibition of protein kinase C affected nuclear permeability. These findings provide evidence that hormones linking to certain G protein-coupled receptors increase nuclear permeability via cytosolic Ca2+. Short term regulation of nuclear permeability may provide a novel mechanism by which such hormones permit transcription factors and other regulatory molecules to enter the nucleus, thereby regulating gene transcription in target cells. PMID:17158097

O'Brien, Elizabeth M.; Gomes, Dawidson A.; Sehgal, Sona; Nathanson, Michael H.

2010-01-01

184

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

185

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

186

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

187

Index Numbers  

Microsoft Academic Search

Index numbers are used to aggregate detailed information on prices and quantities into scalar measures of price and quantity levels or their growth. The paper reviews four main approaches to bilateral index number theory where two price and quantity vectors are to be aggregated: fixed basket and average of fixed baskets, stochastic, test or axiomatic and economic approaches. The paper

Erwin Diewert

2007-01-01

188

Vascular adaptation to a dysfunctional endothelium as a consequence of Shb deficiency  

PubMed Central

Vascular endothelial growth factor (VEGF)-A regulates angiogenesis, vascular morphology and permeability by signaling through its receptor VEGFR-2. The Shb adapter protein has previously been found to relay certain VEGFR-2 dependent signals and consequently vascular physiology and structure was assessed in Shb knockout mice. X-ray computed tomography of vessels larger than 24 ?m diameter (micro-CT) after contrast injection revealed an increased frequency of 48–96 ?m arterioles in the hindlimb calf muscle in Shb knockout mice. Intravital microscopy of the cremaster muscle demonstrated a less regular vasculature with fewer branch points and increased vessel tortuosity, changes that led to an increased blood flow velocity. Reduced in vivo angiogenesis was observed in Shb knockout Matrigel™ plugs. Unlike the wild-type situation, VEGF-A did not provoke a dissociation of VE-cadherin from adherens junctions in Shb knockout venules. The reduced angiogenesis and altered properties of junctions had consequences for two patho-physiological responses to arterial occlusion: vascular permeability was reduced in the Shb knockout cremaster muscle after ligation of one supplying artery and heat-induced blood flow determined by Laser-Doppler measurements was decreased in the hindlimb after ligation of the femoral artery. Consequently, the Shb knockout mouse exhibited structural and functional (angiogenesis and vascular permeability) vascular abnormalities that have implications for understanding the function of VEGF-A under physiological conditions. PMID:22562363

Christoffersson, Gustaf; Zang, Guangxiang; Zhuang, Zhen W.; Vågesjö, Evelina; Simons, Michael; Phillipson, Mia

2014-01-01

189

Nanofabrication of negative refractive index metasurfaces  

Microsoft Academic Search

We designed and fabricated planar metamaterial ‘particles’ (metasurfaces) intended to achieve negative effective refractive index in mid-infrared. We considered double split ring resonators (negative permeability particles) with additional capacitive gaps to compensate for the inertial inductance, as well as complementary double split rings (negative permittivity). We calculated dispersion relations and considered scaling conditions for our structures. For the fabrication of

Zoran Jakši?; Dana Vasiljevi?-Radovi?; Milan Maksimovi?; Milija Sarajli?; Aleksandar Vujani?; Zoran Djuri?

2006-01-01

190

Diabetes and Vascular Disease  

MedlinePLUS

... and Kidney Disease @ 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, ...

191

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

192

Genetics of Vascular Dementia  

PubMed Central

Genetic studies are transforming the way we diagnose, evaluate and treat patients. The era of genome-wide association studies promised to discover common risk variants in heterogeneous disorders where previous small-scale association studies had on the whole failed. However, as we enter the post-association era a degree of disappoint is felt regarding the lack of risk factors with large effect for a number of disorders including vascular disease. Vascular disorders are sporadic by nature, though a familial component has been observed. This review will focus on vascular dementia, the genetic risk factors for vascular disorders and highlight how new technologies may overcome the limitations of genome-wide association and nominate those genes that influence disease risk.

Murray, Melissa E.; Meschia, James F.; Dickson, Dennis W.; Ross, Owen A.

2015-01-01

193

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

194

Vascular endothelium in cancer  

Microsoft Academic Search

The vascular endothelium plays an essential role during organogenesis and in tissue homeostasis. Growing evidence also supports\\u000a its essential and complex role in tumour biology and cancer progression. In particular, excessive proliferation and transformation\\u000a or dysfunction of endothelial cells leads to pathological (lymph)angiogenesis or vascular malfunctions, which are hallmarks\\u000a of neoplastic and malignant disorders. Reciprocal interactions between endothelial cells and

Leonid L. Nikitenko

2009-01-01

195

Intensity of vascular endothelial growth factor expression is associated with increased risk of recurrence and decreased disease-free survival in papillary thyroid cancer  

Microsoft Academic Search

Background. Vascular endothelial growth factor (VEGF) induces proliferation of endothelial cells, stimulates angiogenesis, and increases vascular permeability. Increased VEGF expression has been associated with poor clinical outcomes in many malignancies. Several recent reports have documented over expression of VEGF in papillary thyroid cancer. We hypothesized that increased expression of VEGF would be associated with either an increased risk of recurrence

Colleen M. Lennard; Aneeta Patel; John Wilson; Brian Reinhardt; Caroline Tuman; Cydney Fenton; Elizabeth Blair; Gary L. Francis; R. Michael Tuttle

2001-01-01

196

UK Index  

NSDL National Science Digital Library

The UK Index provides a searchable index of resources in or about the United Kingdom. The Quick Reference section offers links to News Resources in the UK such as the BBC, weather information, UK record charts, and UK related USENET newsgroups. The Foreign & Commonwealth Office provides good advice for travelers. The search engine allows the selection of categories such as arts or business to restrict the search to pages included in one category or a combination of categories.

197

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

198

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

199

Interleukin-8 Regulates Endothelial Permeability by Down-regulation of Tight Junction but not Dependent on Integrins Induced Focal Adhesions  

PubMed Central

Interleukin-8 (IL-8) is a common inflammatory factor, which involves in various non-specific pathological processes of inflammation. It has been found that increased endothelial permeability accompanied with high expression of IL-8 at site of injured endothelium and atherosclerotic plaque at early stages, suggesting that IL-8 participated in regulating endothelial permeability in the developing processes of vascular disease. The purpose of this study is to investigate the regulation effects of IL-8 on the vascular endothelial permeability, and the mRNA and protein expression of tight junction components (i.e., ZO-1, Claudin-5 and Occludin). Endothelial cells were stimulated by IL-8 with the dose of 50, 100 and 200 ng/mL, and duration of 2, 4, 6, 8h, respectively. The mRNA and protein expression level of tight junction components with IL-8 under different concentration and duration was examined by RT-PCR and Western blot, respectively. Meanwhile, the integrins induced focal adhesions event with IL-8 stimulation was also investigated. The results showed that IL-8 regulated the permeability of endothelium by down-regulation of tight junction in a dose- and time-dependence manner, but was not by integrins induced focal adhesions. This finding reveals the molecular mechanism in the increase of endothelial cell permeability induced by IL-8, which is expected to provide a new idea as a therapeutic target in vascular diseases. PMID:24155670

Yu, Hongchi; Huang, Xianliang; Ma, Yunlong; Gao, Min; Wang, Ou; Gao, Ting; Shen, Yang; Liu, Xiaoheng

2013-01-01

200

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

201

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

202

Endothelial nitric oxide synthase activation is critical for vascular leakage during acute  

E-print Network

. vascular permeability, zymosan- stimulated leukocyte infiltration and protein extravasation were assessed in WT and eNOS / mice. Zymosan increases inflamma- tory cell extravasation to the same extent in WT and eNOS / mice, whereas the extravasation of plasma protein is lower in eNOS / mice. Inhibition

Sessa, William C.

203

Permeability in Damaged Porous Rocks  

NASA Astrophysics Data System (ADS)

A new damage model is proposed to assess permeability changes in deformable cracked porous rocks. It is assumed that cracks do not interact. The damage variable may thus be defined as the spectral decomposition of the second-order crack density tensor. Cracks do not intersect but they are connected to the natural porous network. Therefore, damage increases the intrinsic permeability of the porous medium at the scale of the Representative Elementary Volume (REV). A multi-scale approach is adopted to quantify the influence of anisotropic damage on the intrinsic permeability tensor. The thermodynamic framework encompasses both saturated and unsaturated porous media. In this latter case, three stress state variables are required to fully describe the material’s state. Assuming the solid phase to be incompressible makes it possible to resort to two stress state variables only. The stress/strain relationship is derived from Helmholtz free energy. The damage evolution function depends on tensile strains. The intrinsic permeability is split in a natural component and in a damaged component. This latter is first computed by assuming that the flow in cracks is laminar and oriented in the plane of the cracks. In a second stage, the permeability model is improved to account for flow occurring in the direction normal to the crack planes. Computations are presented for saturated rocks. Drained and undrained triaxial compression tests are simulated. Different materials are examined: granite, claystone and sandstone. The results are finally compared with the predictions of the THHMD model previously developed by the first author [1]. The models performance is discussed in the aim of assessing the Excavation Damaged Zone (EDZ).

Arson, C. F.; Pereira, J.

2010-12-01

204

Permeable Pavement Research - Edison, New Jersey  

EPA Science Inventory

This presentation provides the background and summary of results collected at the permeable pavement parking lot monitored at the EPA facility in Edison, NJ. This parking lot is surfaced with permeable interlocking concrete pavers (PICP), pervious concrete, and porous asphalt. ...

205

A review of recent advances in the assessment of bone porosity, permeability, and interstitial fluid flow  

PubMed Central

This contribution reviews recent research performed to assess the porosity and permeability of bone tissue with the objective of understanding interstitial fluid movement. Bone tissue mechanotransduction is considered to occur due to the passage of interstitial pore fluid adjacent to dendritic cell structures in the lacunar-canalicular porosity. The movement of interstitial fluid is also necessary for the nutrition of osteocytes. This review will focus on four topics related to improved assessment of bone interstitial fluid flow. First, the advantages and limitations of imaging technologies to visualize bone porosities and architecture at several length scales are summarized. Second, recent efforts to measure the vascular porosity and lacunar-canalicular microarchitecture are discussed. Third, studies associated with the measurement and estimation of the fluid pressure and permeability in the vascular and lacunar-canalicular domains are summarized. Fourth, the development of recent models to represent the interchange of fluids between the bone porosities is described. PMID:23174418

Cardoso, Luis; Fritton, Susannah P.; Gailani, Gaffar; Benalla, Mohammed; Cowin, Stephen C.

2012-01-01

206

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

207

Depressive behavior and vascular dysfunction: a link between clinical depression and vascular disease?  

PubMed Central

As chronic stress and depression have become recognized as significant risk factors for peripheral vascular disease in patients with no prior history of vasculopathy, we interrogated this relationship utilizing an established mouse model of chronic stress/depressive symptoms from behavioral research. Male mice were exposed to 8 wk of unpredictable chronic mild stress (UCMS; e.g., wet bedding, predator sound/smell, random disruption of light/dark cycle), with indexes of depressive behavior (coat status, grooming, and mobility) becoming exacerbated vs. controls. In vascular rings, constrictor (phenylephrine) and endothelium-independent dilator (sodium nitroprusside) responses were not different between groups, although endothelium-dependent dilation (methacholine) was attenuated with UCMS. Nitric oxide synthase (NOS) inhibition was without effect in UCMS but nearly abolished reactivity in controls, while cyclooxygenase inhibition blunted dilation in both. Combined blockade abolished reactivity in controls, although a significant dilation remained in UCMS that was abolished by catalase. Arterial NO production was attenuated by UCMS, although H2O2 production was increased. UCMS mice demonstrated an increased, although variable, insulin resistance and inflammation. However, while UCMS-induced vascular impairments were consistent, the predictive power of aggregate plasma levels of insulin, TNF-?, IL-1?, and C-reactive peptide were limited. However, when separated into tertiles with regard to vascular outcomes, insulin resistance and hypertension were predictive of the most severe vascular impairments. Taken together, these data suggest that aggregate insulin resistance, inflammation, and hypertension in UCMS mice are not robust predictors of vascular dysfunction, suggesting that unidentified mechanisms may be superior predictors of poor vascular outcomes in this model. PMID:20167667

d'Audiffret, Alexandre C.; Frisbee, Stephanie J.; Stapleton, Phoebe A.; Goodwill, Adam G.; Isingrini, Elsa

2010-01-01

208

Depressive behavior and vascular dysfunction: a link between clinical depression and vascular disease?  

PubMed

As chronic stress and depression have become recognized as significant risk factors for peripheral vascular disease in patients with no prior history of vasculopathy, we interrogated this relationship utilizing an established mouse model of chronic stress/depressive symptoms from behavioral research. Male mice were exposed to 8 wk of unpredictable chronic mild stress (UCMS; e.g., wet bedding, predator sound/smell, random disruption of light/dark cycle), with indexes of depressive behavior (coat status, grooming, and mobility) becoming exacerbated vs. controls. In vascular rings, constrictor (phenylephrine) and endothelium-independent dilator (sodium nitroprusside) responses were not different between groups, although endothelium-dependent dilation (methacholine) was attenuated with UCMS. Nitric oxide synthase (NOS) inhibition was without effect in UCMS but nearly abolished reactivity in controls, while cyclooxygenase inhibition blunted dilation in both. Combined blockade abolished reactivity in controls, although a significant dilation remained in UCMS that was abolished by catalase. Arterial NO production was attenuated by UCMS, although H2O2 production was increased. UCMS mice demonstrated an increased, although variable, insulin resistance and inflammation. However, while UCMS-induced vascular impairments were consistent, the predictive power of aggregate plasma levels of insulin, TNF-alpha, IL-1beta, and C-reactive peptide were limited. However, when separated into tertiles with regard to vascular outcomes, insulin resistance and hypertension were predictive of the most severe vascular impairments. Taken together, these data suggest that aggregate insulin resistance, inflammation, and hypertension in UCMS mice are not robust predictors of vascular dysfunction, suggesting that unidentified mechanisms may be superior predictors of poor vascular outcomes in this model. PMID:20167667

d'Audiffret, Alexandre C; Frisbee, Stephanie J; Stapleton, Phoebe A; Goodwill, Adam G; Isingrini, Elsa; Frisbee, Jefferson C

2010-05-01

209

Ascorbic Acid Prevents Increased Endothelial Permeability Caused by Oxidized Low Density Lipoprotein  

PubMed Central

Mildly oxidized low density lipoprotein (mLDL) acutely increases the permeability of the vascular endothelium to molecules that would not otherwise cross the barrier. We have shown that ascorbic acid tightens the permeability barrier in endothelial barrier in cells, so in this work we tested whether it might prevent the increase in endothelial permeability due to mLDL. Treatment of EA.hy926 endothelial cells with mLDL decreased intracellular GSH and activated the cells to further oxidize the mLDL. mLDL also increased endothelial permeability over 2 h to both inulin and ascorbate in cells cultured on semi-permeable filters. This effect was blocked by microtubule and microfilament inhibitors, but not by chelation of intracellular calcium. Intracellular ascorbate both prevented and reversed the mLDL-induced increase in endothelial permeability, an effect mimicked by other cell-penetrant antioxidants. These results suggest a role for endothelial cell ascorbate in ameliorating an important facet of endothelial dysfunction caused by mLDL. PMID:20815791

May, James M.; Qu, Zhi-chao

2013-01-01

210

Vapor-liquid phase separator permeability results  

NASA Technical Reports Server (NTRS)

Continued studies are described in the area of vapor-liquid phase separator work with emphasis on permeabilities of porous sintered plugs (stainless steel, nominal pore size 2 micrometer). The temperature dependence of the permeability has been evaluated in classical fluid using He-4 gas at atmospheric pressure and in He-2 on the basis of a modified, thermosmotic permeability of the normal fluid.

Yuan, S. W. K.; Frederking, T. H. K.

1981-01-01

211

Jung Index  

NSDL National Science Digital Library

Compiled by Matthew Clapp of the University of Georgia, the Jung Index is a collection of more than 300 online resources about and related to the life and work of Carl Jung, the Swiss psychologist and psychiatrist who founded analytic psychology. Resources are indexed into ten major topic areas and include sections such as Research Resources, Jungian Psychology, and Psychoanalysis, among others. A What's New? section, a What's Cool? section, and the JungNet Newsletter keep frequent visitors up to date on the latest and greatest resources in analytic psychology. In addition, the site provides a glossary of Jungian terms, a gallery of Jungian images, and a moderated forum for Jungian discussion.

1999-01-01

212

Renal permeability alteration precedes hypertension and involves bradykinin in the spontaneously hypertensive rat.  

PubMed Central

Vascular permeability disorders have been described in experimental models, as well as in human hypertension. We recently described the fact that vascular permeability to albumin is heterogeneous in the normal rat. In the present study, we examine the contents of Evans blue dye (EB) bound to albumin in selected organs of unanesthetized Wistar Kyoto (WKY) and in spontaneously hypertensive rats (SHR) at various stages of development of hypertension. EB was injected in the caudal vein of paired 4, 8, 12, and 16-wk-old WKY and SHR. Rats were killed 10 min after EB injection and extraction of the marker was measured in selected tissues. In additional 4 and 16-wk-old animals, bradykinin B1 and B2 receptor antagonists (BKA) were also injected with EB. Renal contents of EB bound to albumin were higher in the SHR than in the WKY: 196 +/- 9, 202 +/- 10, 182 +/- 7, and 196 +/- 9, compared with 158 +/- 8, 155 +/- 7, 138 +/- 7, and 118 +/- 6 micrograms/g dry tissue, in the 4, 8, 12, and 16-wk-old rats, respectively. In the 4-wk-old SHR and WKY, blood pressure values were normal and comparable, yet the alteration in EB permeability was already present in the SHR. Both BKA failed to alter the renal EB extravasation in the WKY, but the B2-BKA restored the renal permeability to control levels in the SHR. We conclude that a selective defect in the renal vascular permeability to EB developed in the SHR. Since this finding precedes hypertension and is corrected by a selective B2-BKA, it is suggested that bradykinin is involved at an early stage of the disease in the SHR. PMID:1602008

Plante, G E; Bissonnette, M; Sirois, M G; Regoli, D; Sirois, P

1992-01-01

213

Regulation of Endothelial Permeability in the Primate Corpora Lutea: Implications for OHSS.  

PubMed

Developing human corpus luteum contains a closely regulated cellular communication system, between luteal steroidogenic cells and endothelial cells. This system guaranties the vascularization process during luteal formation. The process is combined with rapid release of large amounts of progesterone into the bloodstream. The regulation of endothelial proliferation and permeability by LH and human chorionic gonadotropin (hCG) is integral to this process. On the cellular level, endothelial permeability is regulated by intercellular junctions, such as: adherens junctions (AJ), and tight junctions (TJ), which act as zipper-like structures between interacting endothelial cells. Several cell junctional proteins are localized to the corpus luteum, including: Occludin, Nectin 2, Claudin 1 and Claudin 5, as well as, VE-Cadherin. It has been assumed that regulation of AJ- and TJ-proteins is of particular importance for permeability, and accordingly, for the functionality of the corpus luteum in early pregnancy - since treatment with hCG induces down regulation of juntional proteins in the luteal vessels. The effect of hCG on the adhesive molecules is mediated by vascular endothelial growth factor (VEGF). On a functional level, the hCG-dependent and VEGF-mediated decrease of junctional proteins cause a decrease in the density of cell-cell-closure, and accordingly, an increase in endothelial permeability. In doing so, the different junctional proteins are not only directly influenced by VEGF, but also interact among themselves and influence each other reciprocal. Disturbances of this strictly, regulated interactions may explain the development of pathologies with increased vascular permeability, such as the ovarian hyperstimulation syndrome (OHSS). PMID:25301969

Herr, Daniel; Bekes, Inga; Wulff, Christine

2014-10-01

214

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

215

Role of vascular endothelial cell growth factor in Ovarian Hyperstimulation Syndrome.  

PubMed Central

Controlled ovarian hyperstimulation with gonadotropins is followed by Ovarian Hyperstimulation Syndrome (OHSS) in some women. An unidentified capillary permeability factor from the ovary has been implicated, and vascular endothelial cell growth/permeability factor (VEGF) is a candidate protein. Follicular fluids (FF) from 80 women who received hormonal induction for infertility were studied. FFs were grouped according to oocyte production, from group I (0-7 oocytes) through group IV (23-31 oocytes). Group IV was comprised of four women with the most severe symptoms of OHSS. Endothelial cell (EC) permeability induced by the individual FF was highly correlated to oocytes produced (r2 = 0.73, P < 0.001). Group IV FF stimulated a 63+/-4% greater permeability than FF from group I patients (P < 0. 01), reversed 98% by anti-VEGF antibody. Group IV fluids contained the VEGF165 isoform and significantly greater concentrations of VEGF as compared with group I (1,105+/-87 pg/ml vs. 353+/-28 pg/ml, P < 0. 05). Significant cytoskeletal rearrangement of F-actin into stress fibers and a destruction of ZO-1 tight junction protein alignment was caused by group IV FF, mediated in part by nitric oxide. These mechanisms, which lead to increased EC permeability, were reversed by the VEGF antibody. Our results indicate that VEGF is the FF factor responsible for increased vascular permeability, thereby contributing to the pathogenesis of OHSS. PMID:9835623

Levin, E R; Rosen, G F; Cassidenti, D L; Yee, B; Meldrum, D; Wisot, A; Pedram, A

1998-01-01

216

Vascular wall extracellular matrix proteins and vascular diseases.  

PubMed

Extracellular matrix proteins form the basic structure of blood vessels. Along with providing basic structural support to blood vessels, matrix proteins interact with different sets of vascular cells via cell surface integrin or non-integrin receptors. Such interactions induce vascular cell de novo synthesis of new matrix proteins during blood vessel development or remodeling. Under pathological conditions, vascular matrix proteins undergo proteolytic processing, yielding bioactive fragments to influence vascular wall matrix remodeling. Vascular cells also produce alternatively spliced variants that induce vascular cell production of different matrix proteins to interrupt matrix homeostasis, leading to increased blood vessel stiffness; vascular cell migration, proliferation, or death; or vascular wall leakage and rupture. Destruction of vascular matrix proteins leads to vascular cell or blood-borne leukocyte accumulation, proliferation, and neointima formation within the vascular wall; blood vessels prone to uncontrolled enlargement during blood flow diastole; tortuous vein development; and neovascularization from existing pathological tissue microvessels. Here we summarize discoveries related to blood vessel matrix proteins within the past decade from basic and clinical studies in humans and animals - from expression to cross-linking, assembly, and degradation under physiological and vascular pathological conditions, including atherosclerosis, aortic aneurysms, varicose veins, and hypertension. PMID:25045854

Xu, Junyan; Shi, Guo-Ping

2014-11-01

217

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

218

Geochemistry Index  

NSDL National Science Digital Library

This site is the index of a book used in a geochemistry course taught by W. M. White at Cornell University. There are 15 chapters and a table of contents available. All of the chapters are large PDF files and take some time to download. Figures and exercises accompany the text.

William M. White

219

Vascular malformations revisited.  

PubMed

Vascular malformations are congenital anomalies that can affect each part of the vasculature. Combined forms are common and they are often part of complex syndromes. Most malformations are diagnosed during infancy, but some get obvious only later in life. The field of vascular malformations is emerging with recently described new entities and treatments. Still, misdiagnosis is common in this field, leading to nosologic confusion and wrong treatment. Clinical evaluation and imaging are the gold standard for diagnostic confirmation. Sclerotherapy and embolization are the main treatment techniques but are also used preoperatively to reduce blood loss and shrink the lesion if surgery is planned. Despite new treatment options, especially if extensive in size or involving vulnerable structures, vascular malformations are still considered chronic diseases and cause significant morbidity. Common understanding and agreement on terminology and a multidisciplinary approach are the basis of successful treatment and long-term support for these patients. Continuing research in the field of vascular anomalies will improve knowledge and create further treatment options. PMID:25537054

Clemens, Robert K; Pfammatter, Thomas; Meier, Thomas O; Alomari, Ahmad I; Amann-Vesti, Beatrice R

2015-01-01

220

OBESITY AND VASCULAR DYSFUNCTION  

PubMed Central

One of the most profound challenges facing public health and public health policy in Western society is the increased incidence and prevalence of both overweight and obesity. While this condition can have significant consequences for patient mortality and quality of life, it can be further exacerbated as overweight/obesity can be a powerful stimulus for the development of additional risk factors for a negative cardiovascular outcome, including increased insulin resistance, dyslipidemia and hypertension. This manuscript will present the effects of systemic obesity on broad issues of vascular function in both afflicted human populations and in the most relevant animal models. Among the topics that will be covered are alterations to vascular reactivity (both dilator and constrictor responses), adaptations in microvascular network and vessel wall structure, and alterations to the patterns of tissue/organ perfusion as a result of the progression of the obese condition. Additionally, special attention will be paid to the contribution of chronic inflammation as a contributor to alterations in vascular function, as well as the role of perivascular adipose tissue in terms of impacting vessel behavior. When taken together, it is clearly apparent that the development of the obese condition can have profound, and frequently difficult to predict, impacts on integrated vascular function. Much of this complexity appears to have its basis in the extent to which other co-morbidities associated with obesity (e.g., insulin resistance) are present and exert contributing effects. PMID:18571908

Stapleton, Phoebe A.; James, Milinda E.; Goodwill, Adam G.; Frisbee, Jefferson C.

2008-01-01

221

Obesity and vascular dysfunction.  

PubMed

One of the most profound challenges facing public health and public health policy in Western society is the increased incidence and prevalence of both overweight and obesity. While this condition can have significant consequences for patient mortality and quality of life, it can be further exacerbated as overweight/obesity can be a powerful stimulus for the development of additional risk factors for a negative cardiovascular outcome, including increased insulin resistance, dyslipidemia and hypertension. This manuscript will present the effects of systemic obesity on broad issues of vascular function in both afflicted human populations and in the most relevant animal models. Among the topics that will be covered are alterations to vascular reactivity (both dilator and constrictor responses), adaptations in microvascular network and vessel wall structure, and alterations to the patterns of tissue/organ perfusion as a result of the progression of the obese condition. Additionally, special attention will be paid to the contribution of chronic inflammation as a contributor to alterations in vascular function, as well as the role of perivascular adipose tissue in terms of impacting vessel behavior. When taken together, it is clearly apparent that the development of the obese condition can have profound, and frequently difficult to predict, impacts on integrated vascular function. Much of this complexity appears to have its basis in the extent to which other co-morbidities associated with obesity (e.g., insulin resistance) are present and exert contributing effects. PMID:18571908

Stapleton, Phoebe A; James, Milinda E; Goodwill, Adam G; Frisbee, Jefferson C

2008-08-01

222

Pathogenesis of Vascular Anomalies  

PubMed Central

Vascular anomalies are localized defects of vascular development. Most of them occur sporadically, i.e. there is no familial history of lesions, yet in a few cases clear inheritance is observed. These inherited forms are often characterized by multifocal lesions that are mainly small in size and increase in number with patient’s age. On the basis of these inherited forms, molecular genetic studies have unraveled a number of inherited mutations giving direct insight into the pathophysiological cause and the molecular pathways that are implicated. Genetic defects have been identified for hereditary haemorrhagic telangiectasia (HHT), inherited cutaneomucosal venous malformation (VMCM), glomuvenous malformation (GVM), capillary malformation - arteriovenous malformation (CM-AVM), cerebral cavernous malformation (CCM) and some isolated and syndromic forms of primary lymphedema. We focus on these disorders, the implicated mutated genes and the underlying pathogenic mechanisms. We also call attention to the concept of Knudson’s double-hit mechanism to explain incomplete penetrance and the large clinical variation in expressivity of inherited vascular anomalies. This variability renders the making of correct diagnosis of the rare inherited forms difficult. Yet, the identification of the pathophysiological causes and pathways involved in them has had an unprecedented impact on our thinking of their etiopathogenesis, and has opened the doors towards a more refined classification of vascular anomalies. It has also made it possible to develop animal models that can be tested for specific molecular therapies, aimed at alleviating the dysfunctions caused by the aberrant genes and proteins. PMID:21095468

Boon, Laurence M.; Ballieux, Fanny; Vikkula, Miikka

2010-01-01

223

Vascular pathology and osteoarthritis  

Microsoft Academic Search

There is mounting evidence that vascular pathology plays a role in the initiation and\\/or progression of the major disease of joints: osteoarthritis (OA). Potential mechanisms are: episodically reduced blood flow through the small vessels in the subchondral bone at the ends of long bones, and related to this, reduced interstitial fluid flow in subchondral bone. Blood flow may be reduced

D. M. Findlay

2007-01-01

224

Population Index  

NSDL National Science Digital Library

Two excellent bibliographic resources for population studies are the "Population Index" from the Office of Population Research at Princeton University, and "Population Organizations: Finder's Guide" from the Center for Demography and Ecology at the University of Wisconsin-Madison. "Population Index" is a quarterly publication that has been available since 1935. It "covers all fields of interest to demographers, including fertility, mortality, population size and growth, migration, nuptiality and the family, research methodology, projections and predictions, historical demography, and demographic and economic interrelations. Input is derived from original publications including monographs, journal articles, other serial publications, working papers, doctoral dissertations, machine-readable data files, and relevant acquisitions lists and bibliographies." About 3,500 citations are produced annually. Full text for the Index is available at the "Population Index" Web site for 1986-present (Vol. 52-present). Indexes can be searched by author, subject matter, geographical region, or publication year. There is now an experimental free text search capability for the 1994-present issues. "Population Organizations: Finder's Guide" is a no frills "practical tool for population professionals who need a single source for the quick location of organizations that publish and distribute or post population or family planning documents." It contains hundreds of citations, providing organization addresses, phone and FAX numbers, and Internet addresses when available. The Guide is updated every six months and is maintained by Ruth Sandor, Director of the Library of the Center for Demography and Ecology. Office of Population Research, Princeton University: http://opr.princeton.edu/ "Population Organizations: Finder's Guide": gopher://cde2.ssc.wisc.edu:70/00/addazlis gopher to: cde2.ssc.wisc.edu select: Population Organizations: Finder's Guide Center for Demography and Ecology, University of Wisconsin-Madison: http://www.ssc.wisc.edu/cde/

1986-01-01

225

Vascular endothelial growth factor (VEGF) in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS): paradox or paradigm?  

PubMed Central

Acute respiratory distress syndrome (ARDS), the most severe form of acute lung injury (ALI), remains a devastating condition with a high mortality. It is characterised by alveolar injury and increased pulmonary vascular permeability. Vascular endothelial cell growth factor (VEGF) was identified by its properties to increase permeability and act as a cellular growth factor, hence its potential for a key role in the pathogenesis of ALI/ARDS. This review describes the basic biology of VEGF and its receptors as an essential prerequisite to discussing the available and sometimes paradoxical published data, before considering a paradigm for the role of VEGF in the human lung. PMID:16807391

Medford, A R L; Millar, A B

2006-01-01

226

Preeclampsia Does Not Alter Vascular Growth and Expression of CD31 and Vascular Endothelial Cadherin in Human Placentas.  

PubMed

Preeclampsia is characterized by maternal endothelial dysfunction (e.g., increased maternal vascular permeability caused by the disassembly of endothelial junction proteins). However, it is unclear if preeclampsia is associated with impaired vascular growth and expression of endothelial junction proteins in human placentas. Herein, we examined vascular growth in placentas from women with normal term (NT) and preeclamptic (PE) pregnancies using two endothelial junction proteins as endothelial markers: CD31 and vascular endothelial-cadherin (VE-Cad). We also compared protein and mRNA expression of CD31 and VE-Cad between NT and PE placentas, and determined the alternatively spliced expression of CD31 using PCR. We found that CD31 and VE-Cad were immunolocalized predominantly in villous endothelial cells. However, capillary number density (total capillary number per unit villous area) and capillary area density (total capillary lumen area per unit villous area) as well as CD31 and VE-Cad protein and mRNA levels were similar between NT and PE placentas. PCR in combination with sequence analysis revealed a single, full-length CD31, suggesting that there are no alternatively spliced isoform of CD31 expressed in placentas. These data indicate that preeclampsia does not significantly affect vascular growth or the expression of endothelial junction proteins in human placentas. PMID:25362142

Li, Yan; Zhao, Ying-Jie; Zou, Qing-Yun; Zhang, Kevin; Wu, Yan-Ming; Zhou, Chi; Wang, Kai; Zheng, Jing

2015-01-01

227

Vascular neurobehcet disease: correlation with current disease activity forum and systemic vascular involvement.  

PubMed

Behcet's syndrome (BS) is a chronic relapsing vascular inflammatory disease of unknown etiology with high morbidity and mortality. This research aims to study the clinical patterns of CNS disease in a group of patients with BS as well as the frequency and type of the associated radiographic findings suggestive of structural cerebral vascular disease. The findings were studied in relation to disease activity and features of systemic vascular involvement. Forty patients fulfilling the diagnostic criteria of the International Study Group for Behcet's Disease, mean age of 33.56 ± 9.7 years, were enrolled. Patients were subjected to magnetic resonance imaging with conjugate survey of cerebral blood vessels' flow pattern abnormalities by transcranial Doppler study. Thirty healthy controls were included. Behcet's Disease Current Activity Form Score was used. Neuro-Behcet's syndrome (NBS) was diagnosed in 37.5% with headache being the most common (86.6% of cases), pyramidal affection (signs of upper motor neuron lesions/hemiplegia) was reported in 33.3%, attacks of disturbed conscious level in 26.6%, and cranial nerve affection in 6.5%. Of the patients, 66.6% with clinical features of NBS had statistically significant radiographic evidences of cerebrovascular disease (p = 0.01). Patients with NBS had significantly higher disease activity index score (r = 0.69, p = 0.0001). Radiographic findings and flow abnormalities were significantly less in patients on immune suppressants and antiplatelet drugs (p = 0.003, 0.04). BS patients with clinical neurologic disease were found to have radiographic findings suggestive of cerebral vascular disease with high disease activity index score. Drugs like immunosuppressants and oral antiplatelets might retard cerebral vascular disease progression and flow abnormalities, respectively. PMID:22415466

Mohammed, Reem H A; Nasef, Amr; Kewan, Hanady H; Al Shaar, Mohammed

2012-07-01

228

Regulation of the vascular endothelial growth factor (VEGF) receptor Flk-1\\/KDR by estradiol through VEGF in uterus  

Microsoft Academic Search

The induction of vascular endothelial growth factor (VEGF) expression by 17-estradiol (E2) in many target cells, including epithelial cells, fibroblasts and smooth muscle cells, suggests a role for this hormone in the modulation of angiogenesis and vascular permeability. We have already described a cyclic increase in Flk-1\\/KDR- expressing capillaries in the human endometrium during the proliferative and mid-secretory phases, strongly

M A J Herve; G Meduri; F G Petit; T S Domet; G Lazennec; S Mourah; M Perrot-Applanat

2006-01-01

229

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

230

Plant Vascular Biology 2010  

SciTech Connect

This grant supported the Second International Conference on Plant Vascular Biology (PVB 2010) held July 24-28, 2010 on the campus of Ohio State University, Columbus, Ohio. Biao Ding (Ohio State University; OSU) and David Hannapel (Iowa State University; ISU) served as co-chairs of this conference. Biao Ding served as the local organizer. PVB is defined broadly here to include studies on the biogenesis, structure and function of transport systems in plants, under conditions of normal plant growth and development as well as of plant interactions with pathogens. The transport systems cover broadly the xylem, phloem, plasmodesmata and vascular cell membranes. The PVB concept has emerged in recent years to emphasize the integrative nature of the transport systems and approaches to investigate them.

Ding, Biao

2014-11-17

231

Vascular trauma historical notes.  

PubMed

This article provides a brief historical review of treatment of vascular trauma. Although methods for ligation came into use in the second century, this knowledge was lost during the Dark Ages and did not come back until the Renaissance. Many advances in vascular surgery occurred during the Balkan Wars, World War I, and World War II, although without antibiotics and blood banking, the philosophy of life over limb still ruled. Documenting and repairing both arteries and veins became more common during the Korean and Vietnam conflicts. Increased documentation has revealed that the current conflicts have resulted in more arterial injuries than in previous wars, likely because of improved body armor, improvised explosive device attacks, tourniquet use, and improved medical evacuation time. This brief review emphasizes the great value of mentorship and the legacy of the management of arterial and venous injuries to be passed on. PMID:21502112

Rich, Norman M

2011-03-01

232

Congenital Hepatic Vascular Malformations  

Microsoft Academic Search

\\u000a Congenital hepatic vascular malformations are rare entities that result in abnormal shunting of blood through the liver. Three\\u000a different types of shunting can occur: arteriovenous (hepatic artery to hepatic vein), arterioportal (hepatic artery to portal\\u000a vein) and portovenous (portal vein to hepatic vein). Malformations result from alterations in the formation of blood vessels\\u000a during fetal development and can occur as

Guadalupe Garcia-Tsao

233

Neuroprotection in Vascular Dementia  

Microsoft Academic Search

Vascular dementia (VaD) is the second most common form of dementia after Alzheimer’s disease (AD), and one of the major causes of mental and physical disability in developed countries. As such, the identification and implementation of strategies which prevent the development of the condition or enable improvements in patients with VaD are healthcare objectives of the first order. VaD is

Eduardo Martínez-Vila; Manuel Murie-Fernández; Jaime Gállego Pérez-Larraya; Pablo Irimia

2006-01-01

234

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

235

A backward-wave antenna based on negative refractive index LC networks  

Microsoft Academic Search

Recently, there has been significant interest in materials with simultaneously negative permeability and permittivity, also referred to as negative refractive index metamaterials. Metamaterials comprised of straight metal wires and split ring resonators operating in the long wavelength regime exhibit a microwave frequency range with simultaneously negative values of effective permeability and permittivity. We use a 1D L-C loaded transmission line

Anthony Grbic; George V. Eleftheriades

2002-01-01

236

Vascular Stiffness and Increased Pulse Pressure in the Aging Cardiovascular System  

PubMed Central

Aging leads to a multitude of changes in the cardiovascular system, including systolic hypertension, increased central vascular stiffness, and increased pulse pressure. In this paper we will review the effects of age-associated increased vascular stiffness on systolic blood pressure, pulse pressure, augmentation index, and cardiac workload. Additionally we will describe pulse wave velocity as a method to measure vascular stiffness and review the impact of increased vascular stiffness as an index of vascular health and as a predictor of adverse cardiovascular outcomes. Furthermore, we will discuss the underlying mechanisms and how these may be modified in order to change the outcomes. A thorough understanding of these concepts is of paramount importance and has therapeutic implications for the increasingly elderly population. PMID:21845218

Steppan, Jochen; Barodka, Viachaslau; Berkowitz, Dan E.; Nyhan, Daniel

2011-01-01

237

Cumulative Index  

E-print Network

CUMULATIVE INDEX I. Articles (i) By Author Abate, Charles J. "Has Dretske Really Refuted Skepticism?", v.4, n.3 (June, 1977), pp. 169- 175. Abugattas, Juan A. "On the Relation Between Morality and the Notion of God". v.7, n.l (November, 1979...), pp. 47-81. Algeo, Donald. "Why Art?", v.7, n.2 (Spring, 1980), pp. 105-129. Austin, James W. "Rorty's Materialism", v.3, n.l (November, 1975), pp. 20-28. Bell, Gary. "A Characterization of Mathematics". v.8, n.2 (Summer, 1981), pp. 96-104. Bell...

1981-12-01

238

Plasma From Patients With HELLP Syndrome Increases Blood-Brain Barrier Permeability.  

PubMed

Circulating inflammatory factors and endothelial dysfunction have been proposed to contribute to the pathophysiology of hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome. To date, the occurrence of neurological complications in these women has been reported, but few studies have examined whether impairment in blood-brain barrier (BBB) permeability or cerebrovascular reactivity is present in women having HELLP syndrome. We hypothesized that plasma from women with HELLP syndrome causes increased BBB permeability and cerebrovascular dysfunction. Posterior cerebral arteries from female nonpregnant rats were perfused with 20% serum from women with normal pregnancies (n = 5) or women with HELLP syndrome (n = 5), and BBB permeability and vascular reactivity were compared. Plasma from women with HELLP syndrome increased BBB permeability while not changing myogenic tone and reactivity to pressure. Addition of the nitric oxide (NO) synthase inhibitor N(?)-nitro-l-arginine methyl ester caused constriction of arteries that was not different with the different plasmas nor was dilation to the NO donor sodium nitroprusside different between the 2 groups. However, dilation to the small- and intermediate-conductance, calcium-activated potassium channel activator NS309 was decreased in vessels exposed to HELLP plasma. Thus, increased BBB permeability in response to HELLP plasma was associated with selective endothelial dysfunction. PMID:25194151

Wallace, Kedra; Tremble, Sarah M; Owens, Michelle Y; Morris, Rachael; Cipolla, Marilyn J

2014-09-01

239

Quantifying single microvessel permeability in isolated blood-perfused rat lung preparation.  

PubMed

The isolated blood-perfused lung preparation is widely used to visualize and define signaling in single microvessels. By coupling this preparation with real time imaging, it becomes feasible to determine permeability changes in individual pulmonary microvessels. Herein we describe steps to isolate rat lungs and perfuse them with autologous blood. Then, we outline steps to infuse fluorophores or agents via a microcatheter into a small lung region. Using these procedures described, we determined permeability increases in rat lung microvessels in response to infusions of bacterial lipopolysaccharide. The data revealed that lipopolysaccharide increased fluid leak across both venular and capillary microvessel segments. Thus, this method makes it possible to compare permeability responses among vascular segments and thus, define any heterogeneity in the response. While commonly used methods to define lung permeability require postprocessing of lung tissue samples, the use of real time imaging obviates this requirement as evident from the present method. Thus, the isolated lung preparation combined with real time imaging offers several advantages over traditional methods to determine lung microvascular permeability, yet is a straightforward method to develop and implement. PMID:25045895

Kandasamy, Kathirvel; Parthasarathi, Kaushik

2014-01-01

240

Vascular endothelial growth factor signaling in hypoxia and inflammation.  

PubMed

Infection, cancer and cardiovascular diseases are the major causes for morbidity and mortality in the United States according to the Center for Disease Control. The underlying etiology that contributes to the severity of these diseases is either hypoxia induced inflammation or inflammation resulting in hypoxia. Therefore, molecular mechanisms that regulate hypoxia-induced adaptive responses in cells are important areas of investigation. Oxygen availability is sensed by molecular switches which regulate synthesis and secretion of growth factors and inflammatory mediators. As a consequence, tissue microenvironment is altered by re-programming metabolic pathways, angiogenesis, vascular permeability, pH homeostasis to facilitate tissue remodeling. Hypoxia inducible factor (HIF) is the central mediator of hypoxic response. HIF regulates several hundred genes and vascular endothelial growth factor (VEGF) is one of the primary target genes. Understanding the regulation of HIF and its influence on inflammatory response offers unique opportunities for drug development to modulate inflammation and ischemia in pathological conditions. PMID:24610033

Ramakrishnan, S; Anand, Vidhu; Roy, Sabita

2014-03-01

241

Refractive index in the viscous quark-gluon plasma  

NASA Astrophysics Data System (ADS)

Under the framework of the viscous chromohydrodynamics, the gluon self-energy is derived for the quark-gluon plasma with shear viscosity. The viscous chromoelectric permittivity and chromomagnetic permeability are evaluated from the gluon self-energy, through which the chromorefraction index is investigated. The numerical analysis indicates that the chromorefractive index becomes negative in some frequency range. The starting point for that frequency range is around the chromoelectric permittivity pole, and the chromomagnetic permeability pole determines the endpoint. As ?/s increases, the frequency range for the negative refraction becomes wider.

Jiang, Bing-feng; Hou, De-fu; Li, Jia-rong; Gao, Yan-jun

2013-08-01

242

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

243

Potential vascular damage from radiation in the space environment  

NASA Astrophysics Data System (ADS)

Cultured endothelial cells of blood vessels have a Do of 2 Gy for X-rays. A dose of 0.5 Gy of X-rays has an acute effect on vessel diameter. The vessels may show other acute effects such as change in permeability including a change in the blood brain barrier. Changes occurring from late effects of chronic exposure in vascular architecture include telangiectasia and decrease in vascular density. Changes in the perivascular connective tissue particularly collagen may play a role in these changes. After charged particle exposure of 15 and 30 Gy, radiation changes in the blood brain barrier and vascular changes are noted in the nervous system. These long term changes are recorded by PET, MRI, and CT imaging. Chronic exposure to alpha particles causes vascular damage in compact bone resulting in bone infarcts. Using tandem scanning confocal microscopy in-situ imaging of the capillaries and collagen of the papillary dermis provides a non-invasive method of serial recording of changes in irradiated microvasculature.

Griem, M. L.; Robotewskyj, A.; Nagel, R. H.

1994-10-01

244

Angiotensin II induced cerebral microvascular inflammation and increased blood-brain barrier permeability via oxidative stress.  

PubMed

Although hypertension has been implicated in the pathogenesis of vascular disease, its role in inflammatory responses, especially in brain, remains unclear. In this study we found key mechanisms by which angiotensin II (AngII) mediates cerebral microvascular inflammation. C57BL/6 male mice were subjected to slow-pressor dose of AngII infusion using osmotic mini-pumps at a rate of 400 ng/kg/min for 14 days. Vascular inflammation in the brain was evaluated by analysis of leukocyte-endothelial interaction and blood-brain barrier (BBB) permeability. Results from intravital microscopy of pial vessels in vivo, revealed a 4.2 fold (P<0.05, compared to vehicle) increase in leukocyte adhesion on day 4 of AngII infusion. This effect persisted through day 14 of AngII infusion, which resulted in a 2.6 fold (P<0.01, compared to vehicle) increase in leukocyte adhesion. Furthermore, evaluation of BBB permeability by Evans Blue extravasation showed that Ang II significantly affected the BBB, inducing 3.8 times (P<0.05, compared to vehicle) higher permeability. Previously we reported that AngII mediated hypertension promotes oxidative stress in the vasculature. Thus, we used the superoxide scavenger; 4-hydroxy-TEMPO (Tempol) to determine whether AngII via oxidative stress could contribute to higher leukocyte adhesion and increased BBB permeability. Tempol was given via drinking water (2 mmol) on day 4th following Ang II infusion, since oxidative stress increases in this model on day 4. Treatment with Tempol significantly attenuated the increased leukocyte/endothelial interactions and protected the BBB integrity on day 14 of AngII infusion. In conclusion, AngII via oxidative stress increases cerebral microvasculature inflammation and leads to greater immune-endothelial interaction and higher BBB permeability. This finding may open new avenues for the management of nervous system pathology involving cerebrovascular inflammation. PMID:20870012

Zhang, M; Mao, Y; Ramirez, S H; Tuma, R F; Chabrashvili, T

2010-12-15

245

Microfluidic Technology in Vascular Research  

PubMed Central

Vascular cell biology is an area of research with great biomedical relevance. Vascular dysfunction is involved in major diseases such as atherosclerosis, diabetes, and cancer. However, when studying vascular cell biology in the laboratory, it is difficult to mimic the dynamic, three-dimensional microenvironment that is found in vivo. Microfluidic technology offers unique possibilities to overcome this difficulty. In this review, an overview of the recent applications of microfluidic technology in the field of vascular biological research will be given. Examples of how microfluidics can be used to generate shear stresses, growth factor gradients, cocultures, and migration assays will be provided. The use of microfluidic devices in studying three-dimensional models of vascular tissue will be discussed. It is concluded that microfluidic technology offers great possibilities to systematically study vascular cell biology with setups that more closely mimic the in vivo situation than those that are generated with conventional methods. PMID:19911076

van der Meer, A. D.; Poot, A. A.; Duits, M. H. G.; Feijen, J.; Vermes, I.

2009-01-01

246

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

247

Hepatic vascular tumors.  

PubMed

The most common hepatic vascular tumor in the pediatric population is the infantile hepatic hemangioma. Although these lesions have a spectrum of presentations, there are three main subtypes that have been described-focal, multifocal, and diffuse. An algorithm on the workup, treatment, and follow-up of these lesions can be based on this categorization. Recent shifts in the management of hemangiomas with beta-blockers (propranolol) have also influenced the treatment of hepatic hemangiomas. This article reviews the current understanding of hepatic hemangiomas and protocols in the management of these patients. PMID:25241093

Hsi Dickie, Belinda; Fishman, Steven J; Azizkhan, Richard G

2014-08-01

248

Permeability Calculation in a Fracture Network - 12197  

SciTech Connect

Laminar flow of a viscous fluid in the pore space of a saturated fractured rock medium is considered to calculate the effective permeability of the medium. The effective permeability is determined from the flow field which is calculated numerically by using the finite element method. The computation of permeability components is carried out with a few different discretizations for a number of fracture arrangements. Various features such as flow field in the fracture channels, the convergence of permeability, and the variation of permeability among different fracture networks are discussed. The longitudinal permeability in general appears greater than the transverse ones. The former shows minor variations with fracture arrangement whereas the latter appears to be more sensitive to the arrangement. From the calculations of the permeability in a rock medium with a fracture network (two parallel fractures aligned in the direction of 45-deg counterclockwise from the horizontal and two connecting fractures(narrowing, parallel and widening) the following conclusions are drawn. 1. The permeability of fractured medium not only depends on the primary orientation of the main fractures but also is noticeably influenced by the connecting fractures in the medium. 2. The transverse permeability (the permeability in the direction normal to the direction of the externally imposed macro-scale pressure gradient) is only a fraction of the longitudinal one, but is sensitive to the arrangement of the connecting fractures. 3. It is important to figure out the pattern of the fractures that connect (or cross) the main fractures for reliable calculation of the transverse permeability. (authors)

Lee, Cheo Kyung; Kim, Hyo Won [Handong Global University, 3 Namsong-ri, Heunghae-eub, Buk-gu, Pohang, Kyungbuk, 791-708 (Korea, Republic of); Yim, Sung Paal [Korea Atomic Energy Research Institute, Yusong, Daejon, 305-600 (Korea, Republic of)

2012-07-01

249

Local audit in vascular surgery.  

PubMed Central

A 2-year audit of the Southampton Vascular Unit showed marked discrepancies in workload from nationally accepted figures. All forms of reconstructive surgery except emergency aortic aneurysm grafting were performed more frequently than expected. The vascular population is elderly and at high risk from major surgery. Mortality was appreciable in all major vascular procedures and usually cardiac or renal related. The elderly population and resulting workload is likely to increase in the near future. The role of local audit in vascular surgery is emphasised. PMID:2221761

Roberts, J. P.; Smallwood, J. A.; Chant, A. C.; Webster, J. H.

1990-01-01

250

[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

251

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

252

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.

253

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

254

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

255

Permeability Evolution during Deformation of Siliciclastic Sandstones  

E-print Network

Permeability Evolution during Deformation of Siliciclastic Sandstones from Moab, Utah O. Kwon1 Core; 0.33-ft)- diameter cores of four sandstones from the Moab area to investigate the effect of total. Sandstones with low bulk porosities (Dewey Bridge and Slickrock Subkha) exhibited an increase in permeability

256

USERFRIENDLY PERMEABILITY PREDICTING SOFTWARE FOR TECHNICAL TEXTILES  

Microsoft Academic Search

For the simulation of the injection stage of the manufac- turing process of composite materials, the permeability value of the textile is an important input parameter. The permeability of textiles can be determined experi- mentally, however, this is a time and resource consuming process, and no standard procedure is yet available. In this paper we present an easy to use

B. Verleye; G. Morren; S. V. Lomov; H. Sol; D. Roose

257

Characterization of tumor microvascular structure and permeability: comparison between magnetic resonance imaging and intravital confocal imaging  

NASA Astrophysics Data System (ADS)

Solid tumors are characterized by abnormal blood vessel organization, structure, and function. These abnormalities give rise to enhanced vascular permeability and may predict therapeutic responses. The permeability and architecture of the microvasculature in human osteosarcoma tumors growing in dorsal window chambers in athymic mice were measured by confocal laser scanning microscopy (CLSM) and dynamic contrast enhanced magnetic resonance imaging (DCE-MRI). Dextran (40 kDa) and Gadomer were used as molecular tracers for CLSM and DCE-MRI, respectively. A significant correlation was found between permeability indicators. The extravasation rate Ki as measured by CLSM correlated positively with DCE-MRI parameters, such as the volume transfer constant Ktrans and the initial slope of the contrast agent concentration-time curve. This demonstrates that these two techniques give complementary information. Extravasation was further related to microvascular structure and was found to correlate with the fractal dimension and vascular density. The structural parameter values that were obtained from CLSM images were higher for abnormal tumor vasculature than for normal vessels.

Reitan, Nina Kristine; Thuen, Marte; Goa, Pa?L. Erik; de Lange Davies, Catharina

2010-05-01

258

Vascular tissue engineering: microtextured scaffold templates to control organization of vascular smooth muscle cells and  

E-print Network

Vascular tissue engineering: microtextured scaffold templates to control organization of vascular 2004 Abstract The in vitro construction of tissue-engineered small diameter (; Vascular tissue engineering; Fibronectin 1. Introduction The development of tissue-engineered vascular

259

Composites with tuned effective magnetic permeability  

NASA Astrophysics Data System (ADS)

Pendry et al. [J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, IEEE Trans. Microwave Theory Tech. 47, 2075 (1999)] and Smith et al. [D. R. Smith, W. J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz, Phys. Rev. Lett. 84, 4184 (2000)] have shown that the effective magnetic permeability, ?, of free space can be rendered negative over a certain frequency range by a periodic arrangement of very thin conductors with suitable magnetic resonance properties, the so-called split-ring resonators. Because of its rather bulky architecture, this structure does not lend itself to a proper integration into a reasonably thin real composite structural panel. To remedy this fundamental barrier, we invented a new magnetic resonator consisting of very thin folded plates that are suitably nested within one another to form folded-doubled resonators (FDRs) that can be integrated into an actual composite panel. Measurements, using a focused beam electromagnetic characterization system combined with time-domain numerical simulations of the reflection and transmission coefficients of such a composite slab have revealed that indeed the composite has a negative ? over a frequency range of about 9.1-9.35 GHz [S. Nemat-Nasser, S. C. Nemat-Nasser, T. A. Plaisted, A. Starr, and A. Vakil Amirkhizi, in Biomimetics: Biologically Inspired Technologies, edited by Y. Bar Cohen (CRC Press, Boca Raton, FL, 2006)]. Thus, it has become possible to construct a structural composite panel with negative index of refraction by simultaneously creating negative effective ? and ? [V. G. Veselago, Sov. Phys. Usp. 10, 509 (1968); R. A. Shelby, D. R. Smith, and S. Schultz, Science 292, 77 (2001); A. F. Starr, P. M. Rye, D. R. Smith, and S. Nemat-Nasser, Phys. Rev. B 70, 113102 (2004)].

Amirkhizi, Alireza V.; Nemat-Nasser, Sia

2007-07-01

260

Compact rock material gas permeability properties  

NASA Astrophysics Data System (ADS)

Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO2, shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10-19 m2; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10-17 m2; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which ? > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens' permeability evolution is related to the relative particle movements and microcrack closure.

Wang, Huanling; Xu, Weiya; Zuo, Jing

2014-09-01

261

Renal and Vascular Mechanisms of Thiazolidinedione-Induced Fluid Retention  

PubMed Central

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor subtype ? (PPAR?) activators that are clinically used as an insulin sensitizer for glycemic control in patients with type 2 diabetes. Additionally, TZDs exhibit novel anti-inflammatory, antioxidant, and antiproliferative properties, indicating therapeutic potential for a wide variety of diseases associated with diabetes and other conditions. The clinical applications of TZDs are limited by the common major side effect of fluid retention. A better understanding of the molecular mechanism of TZD-induced fluid retention is essential for the development of novel therapies with improved safety profiles. An important breakthrough in the field is the finding that the renal collecting duct is a major site for increased fluid reabsorption in response to rosiglitazone or pioglitazone. New evidence also indicates that increased vascular permeability in adipose tissues may contribute to edema formation and body weight gain. Future research should therefore be directed at achieving a better understanding of the detailed mechanisms of TZD-induced increases in renal sodium transport and in vascular permeability. PMID:18784848

Yang, Tianxin; Soodvilai, Sunhapas

2008-01-01

262

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

263

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

264

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

265

Propagation of electromagnetic solitons in nonlinear negative-index materials  

Microsoft Academic Search

The propagation property of electromagnetic solitons in the negative-index material with a nonlinear polarization is investigated numerically. The role of the negative self-steepening and the higher-order nonlinear dispersion effects, which are resulted from the dispersive permeability of negative-index material, in soliton propagation is identified. It is shown that, like the positive self-steepening effect, the negative self-steepening effect also leads to

Xiaoyan Song; Shuangchun Wen

2006-01-01

266

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

267

Wisconsin Vascular Plants  

NSDL National Science Digital Library

The staff of the Wisconsin State Herbarium have created this excellent online resource for exploring the world of vascular plants in Wisconsin, complete with several helpful finding aids to navigate the collection. Based on decades of research (including the ground breaking work of John Curtis), visitors can search for plants by name, habitat, status, and county. Also, visitors to the site can browse the thousands of selections by genera, common name, and family. A wealth of information is included about each plant, including (in most cases) a photograph of the plant in its habitat, a map indicating where the plant may be found in Wisconsin, and its common names. Other features of the site include a guide to "What's Blooming" around Wisconsin, a key to the conifers of Wisconsin, and information about other current projects of the Wisconsin State Herbarium.

2007-12-13

268

Caffeine's Vascular Mechanisms of Action  

PubMed Central

Caffeine is the most widely consumed stimulating substance in the world. It is found in coffee, tea, soft drinks, chocolate, and many medications. Caffeine is a xanthine with various effects and mechanisms of action in vascular tissue. In endothelial cells, it increases intracellular calcium stimulating the production of nitric oxide through the expression of the endothelial nitric oxide synthase enzyme. Nitric oxide is diffused to the vascular smooth muscle cell to produce vasodilation. In vascular smooth muscle cells its effect is predominantly a competitive inhibition of phosphodiesterase, producing an accumulation of cAMP and vasodilation. In addition, it blocks the adenosine receptors present in the vascular tissue to produce vasoconstriction. In this paper the main mechanisms of action of caffeine on the vascular tissue are described, in which it is shown that caffeine has some cardiovascular properties and effects which could be considered beneficial. PMID:21188209

Echeverri, Darío; Montes, Félix R.; Cabrera, Mariana; Galán, Angélica; Prieto, Angélica

2010-01-01

269

Vascular Development in the Zebrafish  

PubMed Central

The zebrafish has emerged as an excellent vertebrate model system for studying blood and lymphatic vascular development. The small size, external and rapid development, and optical transparency of zebrafish embryos are some of the advantages the zebrafish model system offers. Multiple well-established techniques have been developed for imaging and functionally manipulating vascular tissues in zebrafish embryos, expanding on and amplifying these basic advantages and accelerating use of this model system for studying vascular development. In the past decade, studies performed using zebrafish as a model system have provided many novel insights into vascular development. In this article we discuss the amenability of this model system for studying blood vessel development and review contributions made by this system to our understanding of vascular development. PMID:22553495

Gore, Aniket V.; Monzo, Kathryn; Cha, Young R.; Pan, Weijun; Weinstein, Brant M.

2012-01-01

270

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

271

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

272

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

273

Validation/enhancement of the "Jones-Owens" technique for the prediction of permeability in low permeability gas sands  

E-print Network

This work presents the validation and enhancement of existing correlations for estimating and predicting the permeability in low permeability gas sands. The "original" problem of predicting the corrected or "liquid equivalent" permeability has been...

Florence, Francois-Andre

2007-09-17

274

Effect of VEGF Treatment on the Blood-Spinal Cord Barrier Permeability in Experimental Spinal Cord Injury: Dynamic Contrast-Enhanced Magnetic Resonance Imaging  

PubMed Central

Abstract Compromised blood-spinal cord barrier (BSCB) is a factor in the outcome following traumatic spinal cord injury (SCI). Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis and vascular permeability. The role of VEGF in SCI is controversial. Relatively little is known about the spatial and temporal changes in the BSCB permeability following administration of VEGF in experimental SCI. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) studies were performed to noninvasively follow spatial and temporal changes in the BSCB permeability following acute administration of VEGF in experimental SCI over a post-injury period of 56 days. The DCE-MRI data was analyzed using a two-compartment pharmacokinetic model. Animals were assessed for open field locomotion using the Basso-Beattie-Bresnahan score. These studies demonstrate that the BSCB permeability was greater at all time points in the VEGF-treated animals compared to saline controls, most significantly in the epicenter region of injury. Although a significant temporal reduction in the BSCB permeability was observed in the VEGF-treated animals, BSCB permeability remained elevated even during the chronic phase. VEGF treatment resulted in earlier improvement in locomotor ability during the chronic phase of SCI. This study suggests a beneficial role of acutely administered VEGF in hastening neurobehavioral recovery after SCI. PMID:19226205

Patel, Chirag B.; Cohen, David M.; Ahobila-Vajjula, Pallavi; Sundberg, Laura M.; Chacko, Tessy

2009-01-01

275

Oxygen permeability of calcia-stabilized zirconia  

Microsoft Academic Search

Oxygen permeability of commercial calcia-stabilized zirconia has been measured at 1673 to 1823 K by the following cell; O2 ZrO2(CaO) N2 - O2 (P’tO2 = 1 atm) solid electrolyte (P?O2 = 0.39 - 1010-3 atm). Oxygen permeability of calcia-stabilized zirconia is proportional to (1 - P?O2\\u000a 1\\/4). From the permeability measurement, the conduction properties of the electrolyte were log ?-‡

Masanori Iwase; Toshisada Mori

1978-01-01

276

Correlation of soil radon and permeability with indoor radon potential in Ottawa.  

PubMed

Soil gas radon and soil gas permeability measurements were conducted at 32 sites across the five most populated communities in the city of Ottawa where indoor radon measurements were available for 167 houses. A soil radon index (SRI) determined from the soil radon concentration and the soil gas permeability was used to characterise radon availability from soil to air. This study demonstrated that the average SRI in a community area correlates with the indoor radon potential (the percentage of homes above 200 Bq m(-3)) in that community. Soil gas radon concentrations together with soil gas permeability measurements can be a useful tool for the prediction of the indoor radon potential in the development of a Canadian radon risk map. PMID:19617242

Chen, Jing; Falcomer, Renato; Bergman, Lauren; Wierdsma, Jessica; Ly, Jim

2009-08-01

277

Renal interstitial permeability changes induced by microbubble-enhanced diagnostic ultrasound.  

PubMed

Ultrasound-targeted microbubble (MB) destruction (UTMD) has been shown to increase the glomerular permeability, providing a potential novel therapeutic approach in targeted drug release for kidney diseases. Therefore, we investigated the impact of UTMD on renal interstitial permeability using MB-mediated diagnostic ultrasound (DUS). The left kidney of Sprague-Dawley (SD) rat was insonated by UTMD with either continuous or intermittent mode for 5?min. Evans blue (EB) revealed that both modes induced renal vascular permeability increase after DUS but recovered after 24?h. Intermittent insonation caused more severe injury than continuous mode. Red blood cells leaked out of the capillaries into interstitium without glomerular capillary hemorrhage (GCH) by hematoxylin and eosin (HE) staining. Electronic microscopy revealed the disruption of focal capillary wall in interstitial tissues. Morphological results confirmed capillary wall recovered in 24?h post-treatment. Results from fluorescence-labeled MBs showed that MBs were mainly localized in the interstitial portion of the tubular region and retained at 24?h. Intriguingly, urinalysis showed no clinical proteinuria after treatment. Our results indicated that MB plus DUS specifically and reversibly enhanced the interstitial permeability without affecting glomerulus, which may be developed into a therapeutic approach for targeting drug release to individual renal compartments. PMID:23627569

Li, Peijing; Gao, Yunhua; Zhang, Jihang; Liu, Zheng; Tan, Kaibin; Hua, Xing; Gong, Jinling

2013-05-01

278

21 CFR 870.3250 - Vascular clip.  

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3250 Vascular clip. (a) Identification. A vascular clip...

2014-04-01

279

21 CFR 870.4450 - Vascular clamp.  

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4450 Vascular clamp. (a) Identification. A vascular clamp...

2014-04-01

280

21 CFR 870.3250 - Vascular clip.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3250 Vascular clip. (a) Identification. A vascular clip...

2013-04-01

281

21 CFR 870.4450 - Vascular clamp.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4450 Vascular clamp. (a) Identification. A vascular clamp...

2013-04-01

282

A computational tool for quantitative analysis of vascular networks.  

PubMed

Angiogenesis is the generation of mature vascular networks from pre-existing vessels. Angiogenesis is crucial during the organism' development, for wound healing and for the female reproductive cycle. Several murine experimental systems are well suited for studying developmental and pathological angiogenesis. They include the embryonic hindbrain, the post-natal retina and allantois explants. In these systems vascular networks are visualised by appropriate staining procedures followed by microscopical analysis. Nevertheless, quantitative assessment of angiogenesis is hampered by the lack of readily available, standardized metrics and software analysis tools. Non-automated protocols are being used widely and they are, in general, time--and labour intensive, prone to human error and do not permit computation of complex spatial metrics. We have developed a light-weight, user friendly software, AngioTool, which allows for quick, hands-off and reproducible quantification of vascular networks in microscopic images. AngioTool computes several morphological and spatial parameters including the area covered by a vascular network, the number of vessels, vessel length, vascular density and lacunarity. In addition, AngioTool calculates the so-called "branching index" (branch points/unit area), providing a measurement of the sprouting activity of a specimen of interest. We have validated AngioTool using images of embryonic murine hindbrains, post-natal retinas and allantois explants. AngioTool is open source and can be downloaded free of charge. PMID:22110636

Zudaire, Enrique; Gambardella, Laure; Kurcz, Christopher; Vermeren, Sonja

2011-01-01

283

A Computational Tool for Quantitative Analysis of Vascular Networks  

PubMed Central

Angiogenesis is the generation of mature vascular networks from pre-existing vessels. Angiogenesis is crucial during the organism' development, for wound healing and for the female reproductive cycle. Several murine experimental systems are well suited for studying developmental and pathological angiogenesis. They include the embryonic hindbrain, the post-natal retina and allantois explants. In these systems vascular networks are visualised by appropriate staining procedures followed by microscopical analysis. Nevertheless, quantitative assessment of angiogenesis is hampered by the lack of readily available, standardized metrics and software analysis tools. Non-automated protocols are being used widely and they are, in general, time - and labour intensive, prone to human error and do not permit computation of complex spatial metrics. We have developed a light-weight, user friendly software, AngioTool, which allows for quick, hands-off and reproducible quantification of vascular networks in microscopic images. AngioTool computes several morphological and spatial parameters including the area covered by a vascular network, the number of vessels, vessel length, vascular density and lacunarity. In addition, AngioTool calculates the so-called “branching index” (branch points / unit area), providing a measurement of the sprouting activity of a specimen of interest. We have validated AngioTool using images of embryonic murine hindbrains, post-natal retinas and allantois explants. AngioTool is open source and can be downloaded free of charge. PMID:22110636

Zudaire, Enrique; Gambardella, Laure; Kurcz, Christopher; Vermeren, Sonja

2011-01-01

284

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

285

Targeting Vascular Endothelial Growth Factor (VEGF) for Antitumor Therapy, by Anti-VEGF Neutralizing Monoclonal Antibodies or by VEGF Receptor Tyrosine-kinase Inhibitors  

Microsoft Academic Search

Vascular endothelial growth factor\\/vascular permeability factor (VEGF\\/VPF) is an important mediator of tumor-induced angiogenesis and represents a potential target for innovative anticancer therapy. In several animal models, neutralizing anti-VEGF\\/VPF antibodies have shown encouraging inhibitory effects on solid tumor growth, ascites formation and metastatic dissemination. Targeting the VEGF signaling pathway by means of VEGF receptor tyrosine-kinase inhibitors has shown similar efficacy

Jean-Marc Schlaeppi; Jeanette M. Wood

1999-01-01

286

NADPH Oxidases in Vascular Pathology  

PubMed Central

Abstract Significance: Reactive oxygen species (ROS) play a critical role in vascular disease. While there are many possible sources of ROS, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases play a central role. They are a source of “kindling radicals,” which affect other enzymes, such as nitric oxide synthase endothelial nitric oxide synthase or xanthine oxidase. This is important, as risk factors for atherosclerosis (hypertension, diabetes, hypercholesterolemia, and smoking) regulate the expression and activity of NADPH oxidases in the vessel wall. Recent Advances: There are seven isoforms in mammals: Nox1, Nox2, Nox3, Nox4, Nox5, Duox1 and Duox2. Nox1, Nox2, Nox4, and Nox5 are expressed in endothelium, vascular smooth muscle cells, fibroblasts, or perivascular adipocytes. Other homologues have not been found or are expressed at very low levels; their roles have not been established. Nox1/Nox2 promote the development of endothelial dysfunction, hypertension, and inflammation. Nox4 may have a role in protecting the vasculature during stress; however, when its activity is increased, it may be detrimental. Calcium-dependent Nox5 has been implicated in oxidative damage in human atherosclerosis. Critical Issues: NADPH oxidase-derived ROS play a role in vascular pathology as well as in the maintenance of normal physiological vascular function. We also discuss recently elucidated mechanisms such as the role of NADPH oxidases in vascular protection, vascular inflammation, pulmonary hypertension, tumor angiogenesis, and central nervous system regulation of vascular function and hypertension. Future Directions: Understanding the role of individual oxidases and interactions between homologues in vascular disease is critical for efficient pharmacological regulation of vascular NADPH oxidases in both the laboratory and clinical practice. Antioxid. Redox Signal. 20, 2794–2814. PMID:24180474

Konior, Anna; Schramm, Agata; Czesnikiewicz-Guzik, Marta

2014-01-01

287

Regulation of Endothelial Permeability in the Corpus Luteum: A Review of the Literature  

PubMed Central

The development of the human corpus luteum (yellow body) is dictated by a strictly controlled system of mutually communicating cells, the luteal steroid hormone-producing cells and endothelial cells. This cell-to-cell communication facilitates control of neoangiogenesis which is a prerequisite for the development of the corpus luteum and its function, the rapid release of large amounts of progesterone into the blood-vascular system. Preconditions for this process are the hormonal regulation of endothelial cell proliferation as well as of vascular permeability through LH and hCG. The morphological correlates of endothelial permeability are cell-to-cell adhesion molecules such as adherens junctions (AJ) and tight junctions (TJ) that open and close the gaps between mutually interacting, neighbouring endothelial cells like a “zip fastener”. Various types of cell adhesion molecules have been detected in the corpus luteum such as occludin, claudin 1 and claudin 5 as well as VE-cadherin. It may be assumed that the regulation of AJ and TJ proteins is of particular importance for the permeability and thus for the function of the corpus luteum in early pregnancy since hCG treatment leads to a down-regulation of cell adhesion molecules in the luteal vessels. This effect is apparently mediated by VEGF. From a functional point of view, the hCG-dependent and VEGF-mediated down-regulation of cell adhesion molecules leads to a reduced transmissibility of cell-to-cell contacts and thus to an increased endothelial permeability. In this process the various cell adhesion molecules are not only directly regulated by VEGF but they also mutually interact and thus influence one another. PMID:24771896

Herr, D.; Bekes, I.; Wulff, C.

2013-01-01

288

Quantifying the Evolution of Vascular Barrier Disruption in Advanced Atherosclerosis with Semipermeant Nanoparticle Contrast Agents  

PubMed Central

Rationale Acute atherothrombotic occlusion in heart attack and stroke implies disruption of the vascular endothelial barrier that exposes a highly procoagulant intimal milieu. However, the evolution, severity, and pathophysiological consequences of vascular barrier damage in atherosclerotic plaque remain unknown, in part because quantifiable methods and experimental models are lacking for its in vivo assessment. Objective To develop quantitative nondestructive methodologies and models for detecting vascular barrier disruption in advanced plaques. Methods and Results Sustained hypercholesterolemia in New Zealand White (NZW) rabbits for >7–14 months engendered endothelial barrier disruption that was evident from massive and rapid passive penetration and intimal trapping of perfluorocarbon-core nanoparticles (PFC-NP: ?250 nm diameter) after in vivo circulation for as little as 1 hour. Only older plaques (>7 mo), but not younger plaques (<3 mo) demonstrated the marked enhancement of endothelial permeability to these particles. Electron microscopy revealed a complex of subintimal spongiform channels associated with endothelial apoptosis, superficial erosions, and surface-penetrating cholesterol crystals. Fluorine (19F) magnetic resonance imaging and spectroscopy (MRI/MRS) enabled absolute quantification (in nanoMolar) of the passive permeation of PFC-NP into the disrupted vascular lesions by sensing the unique spectral signatures from the fluorine core of plaque-bound PFC-NP. Conclusions The application of semipermeant nanoparticles reveals the presence of profound barrier disruption in later stage plaques and focuses attention on the disrupted endothelium as a potential contributor to plaque vulnerability. The response to sustained high cholesterol levels yields a progressive deterioration of the vascular barrier that can be quantified with fluorine MRI/MRS of passively permeable nanostructures. The possibility of plaque classification based on the metric of endothelial permeability to nanoparticles is suggested. PMID:22028868

Zhang, Huiying; Zhang, Lei; Myerson, Jacob; Bibee, Kristin; Scott, Michael; Allen, John; Sicard, Gregorio; Lanza, Gregory; Wickline, Samuel

2011-01-01

289

Tumor vascular permeabilization using localized mild hyperthermia to improve macromolecule transport.  

PubMed

The abnormal tumor vasculature presents a major challenge to the adequate delivery of chemotherapeutics, often limiting efficacy. We developed a nanoparticle-based technique to deliver localized mild hyperthermia (MHT) used to transiently alter tumor vascular transport properties and enhance transport of macromolecules into tumor interstitium. The strategy involved administering and localizing accumulation of stealth gold nanorods (GNRs, 103 ?g of GNRs/g of tumor), and irradiating tumor with a low-photon laser flux (1 W/cm(2)) to generate MHT. The treatment increased vascular permeability within 24 h after treatment, allowing enhanced transport of macromolecules up to 54 nm in size. A mathematical model is used to describe changes in tumor mass transport properties where the rate of macromolecular exchange between interstitial and vascular region (R) and maximum dye enhancement (Ymax) of 23-nm dextran dye is analytically solved. During enhanced permeability, R increased by 200% while Ymax increased by 30% relative to untreated group in pancreatic CAPAN-1 tumors. MHT treatment also enhanced transport of larger dextran dye (54 nm) as assessed by intravital microscopy, without causing occlusive cellular damage. Enhanced vascular transport was prolonged for up to 24 h after treatment, but reversible with transport parameters returning to basal levels after 36 h. This study indicates that localized mild hyperthermia treatment opens a transient time-window with which to enable and augment macromolecule transport and potentially improve therapeutic efficacy. From the clinical editor: In this study, local intra-tumor mild hyperthermia is induced using a nanoparticle-based approach utilizing stealth gold nanorods and irradiating the tumor with low-photon laser flux, resulting in locally increased vascular permeability enabling enhanced delivery of therapeutics, including macromolecules up to 54 nm in size. Similar approaches would be very helpful in addressing treatment-resistant malignancies in clinical practice. PMID:24262998

Kirui, Dickson K; Koay, Eugene J; Guo, Xiaojing; Cristini, Vittorio; Shen, Haifa; Ferrari, Mauro

2014-10-01

290

Dual energy micro-CT imaging of radiation-induced vascular changes in primary mouse sarcomas  

PubMed Central

Purpose To evaluate the effects of radiation therapy on primary tumor vasculature using dual energy (DE) micro-computed tomography (micro-CT). Methods and Materials The Cre-loxP system was used to generate primary sarcomas with mutant Kras and p53. Unirradiated tumors were compared to tumors irradiated with 20 Gy. A long-circulating PEGylated liposomal-iodinated contrast agent was administered one day after treatment, and mice were imaged immediately after injection (day 1) and three days later (day 4) using DE micro-CT. CT-derived tumor sizes were used to assess tumor growth. After DE decomposition, iodine maps were used to assess tumor fractional blood volume (FBV) at day 1 and tumor vascular permeability at day 4. For comparison, tumor vascularity and vascular permeability were also evaluated histologically using CD31 immunofluorescence and fluorescently-labeled dextrans. Results Radiation treatment significantly decreased tumor growth (P<0.05). There was a positive correlation between CT-measurement of tumor FBV and extravasated iodine with microvascular density (MVD) (R2=0.53) and dextran accumulation (R2=0.63), respectively. Despite no change in MVD measured by histology, tumor FBV significantly increased after irradiation as measured by DE micro-CT (0.070 vs. 0.091, P<0.05). Both dextran and liposomal-iodine accumulation in tumors increased significantly after irradiation with dextran fractional area increasing 4.2-fold and liposomal-iodine concentration increasing 3.0-fold. Conclusions DE micro-CT is an effective tool for non-invasive assessment of vascular changes in primary tumors. Tumor blood volume and vascular permeability increased after a single therapeutic dose of radiation treatment. PMID:23122984

Moding, Everett J.; Clark, Darin P.; Qi, Yi; Li, Yifan; Ma, Yan; Ghaghada, Ketan; Johnson, G. Allan; Kirsch, David G.; Badea, Cristian T.

2013-01-01

291

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

292

Flexible Sandwich Diaphragms Are Less Permeable  

NASA Technical Reports Server (NTRS)

Diaphragms for use in refrigerator compressors made as laminates of commercially available elastomers and metals. Diaphragms flexible, but less permeable by chlorofluorocarbon refrigerant fluids than diaphragms made of homogeneous mixtures of materials.

Michalovic, John G.; Vassallo, Franklin A.

1993-01-01

293

Improved permeability prediction using multivariate analysis methods  

E-print Network

Predicting rock permeability from well logs in uncored wells is an important task in reservoir characterization. Due to the high costs of coring and laboratory analysis, typically cores are acquired in only a few wells. Since most wells are logged...

Xie, Jiang

2009-05-15

294

Complex permeability measurements of microwave ferrites  

SciTech Connect

A rigorous and accurate method for the experimental determination of the complex permeability of demagnetized ferrites at microwave frequencies is presented. The measurement uses low-loss dielectric ring resonators, is nondestructive, and allows complex permeability characterization of a single ferrite sample to be performed at frequencies from 2 GHz to 25 GHz. A wide variety of ceramic microwave ferrites having various compositions and differing saturation magnetizations were measured in the demagnetized state. Generally, at any frequency greater than gyromagnetic resonance, the real part of the complex permeability increases as saturation magnetization increases. For the same frequency magnetic losses increases as saturation magnetization increases. The real permeability results are compared with magnetostatic theoretical predictions. Measurement data show excellent agreement with theoretical predictions, but only when 2{pi}{gamma}M{sub s}/{omega} < 0.75, where {gamma} is the gyromagnetic ratio, M{sub s} is saturation magnetization, and {omega} is the radian rf frequency.

Geyer, R.G. [National Institute of Standards and Technology, Boulder, CO (United States). Electromagnetic Fields Div.; Krupka, J. [Instytut Mikroelektroniki i Optoelektroniki Politechniki Warszawskiej, Warszawa (Poland)

1996-12-31

295

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

296

Index des mots-cls Keywords index  

E-print Network

Index des mots-clés Keywords index A Abies, 823 Abies alba, 265 acacia, 93 Acacia cyanophylla Lindl., 335 Acacia mearnsii De Wild., 833 acclimation, 19 AFLP, 627 AFLP, SSR, EST markers, 637 Agrobacterium

Boyer, Edmond

297

Vascular Cognitive Impairment: Prodromal Stages of Ischemic Vascular Dementia  

Microsoft Academic Search

Background\\/Aims: To describe the natural history of the prodromal stages of ischemic vascular dementia (pVaD). Methods: A sample of 314 inpatients with pVaD or a clini- cal diagnosis of vascular dementia (VaD; lacunar state, Binswanger’s disease, pure cortical VaD, corticosubcortical and strategic infarctions) admitted to a teaching tertiary center during a 13-year period was assessed (retrospectively n = 88, prospectively

Ciro Ramos-Estébanez; Ignacio Moral-Arce; Roberto Muñoz-Arrondo; Andrés González-Mandly; Pedro Matorras-Galán; Jesús González-Macias; José Luis Hernández-Hernández

2008-01-01

298

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

299

Compression and permeability behavior of natural mudstones  

NASA Astrophysics Data System (ADS)

Mudstones compose nearly 70% of the volume of sedimentary basins, yet they are among the least studied of sedimentary rocks. Their low permeability and high compressibility contribute to overpressure around the world. Despite their fundamental importance in geologic processes and as seals for anthropogenic-related storage, a systematic, process-based understanding of the interactions between porosity, compressibility, permeability, and pore-size distribution in mudstones remains elusive. I use sediment mixtures composed of varying proportions of natural mudstone such as Boston Blue Clay or Nankai mudstone and silt-sized silica to study the effect of composition on permeability and compressibility during burial. First, to recreate natural conditions yet remove variability and soil disturbance, I resediment all mixtures in the laboratory to a total stress of 100 kPa. Second, in order to describe the systematic variation in permeability and compressibility with clay fraction, I uniaxially consolidate the resedimented samples to an effective stress equivalent to about 2 km of burial under hydrostatic conditions. Scanning electron microscope images provide insights on microstructure. My experiments illuminate the controls on mudstone permeability and compressibility. At a given porosity, vertical permeability increases by an order of magnitude for clay contents ranging from 59% to 34% by mass whereas compressibility reduces by half at a given vertical effective stress. I show that the pore structure can be described by a dual-porosity system, where one rock fraction is dominated by silt where large pores are present and the majority of flow occurs and the other fraction is dominated by clay where limited flow occurs. I use this concept to develop a coupled compressibility-permeability model in order to predict porosity, permeability, compressibility, and coefficient of consolidation. These results have fundamental implications for a range of problems in mudstones. They can be applied to carbon sequestration, hydrocarbon trapping, basin modeling, overpressure distribution and geometry as well as morphology of thrust belts, and an understanding of gas-shale behavior.

Schneider, Julia

300

Vascular endothelial growth factor mRNA and protein expression in airway epithelial cell lines in vitro.  

PubMed

Vascular endothelial growth factor (VEGF) plays multifunctional roles in vascular permeability, repair and remodelling processes, in addition to the maintenance of vascular structure and function. In the present study, the potential of airway epithelial cell lines, BEAS-2B cells and A549 cells, to release and express VEGF in unstimulated and stimulated conditions was evaluated. The secretion and expression of VEGF were evaluated by enzyme-linked immunosorbant assay and by reverse transcriptase-polymerase chain reaction. The isoforms of released VEGF were determined by high-performance liquid chromatography. BEAS-2B cells and A549 cells released VEGF constitutively. Interleukin (IL)-1beta and tumour necrosis factor (TNF)-alpha augmented the release of VEGF in a time- and dose-dependent manner. The released VEGF was 165 amino acid residues in either condition. Pseudomonas aeruginosa lipopolysaccharide (LPS), interferon (IFN)-gamma, smoke extract (SE), neutrophil elastase (NE), and bradykinin stimulated the release of VEGF. Keracinocyte growth factor (KGF), which reduces vascular permeability, also stimulated both cells to release VEGF. VEGF messenger ribonucleic acid (mRNA) was expressed both time- and dose-dependently at 2 h, and declined after 2 h in response to IL-1beta and TNF-alpha. The expression of VEGF mRNA in airway epithelial cells was also augmented by LPS, IFN-gamma, SE, NE, and KGF stimulation. These data suggest that airway epithelial cells may regulate the maintenance of vascular structure and function, as well as vascular permeability, repair and remodelling processes, in a variety of lung conditions by expressing vascular endothelial growth factor. PMID:12503703

Koyama, S; Sato, E; Tsukadaira, A; Haniuda, M; Numanami, H; Kurai, M; Nagai, S; Izumi, T

2002-12-01

301

Reflection coefficient and permeability of urea and ethylene glycol in the human red cell membrane  

SciTech Connect

The reflection coefficient (sigma) and permeability (P) of urea and ethylene glycol were determined by fitting the equations of Kedem and Katchalsky (1958) to the change in light scattering produced by adding a permeable solute to a red cell suspension. The measurements incorporated three important modifications: (a) the injection artifact was eliminated by using echinocyte cells; (b) the use of an additional adjustable parameter (Km), the effective dissociation constant at the inner side of the membrane; (c) the light scattering is not directly proportional to cell volume (as is usually assumed) because refractive index and scattering properties of the cell depend on the intracellular permeable solute concentration. This necessitates calibrating for known changes in refractive index (by the addition of dextran) and cell volume (by varying the NaCl concentration). The best fit was for sigma . 0.95, Po . 8.3 X 10(-4) cm/s, and Km . 100 mM for urea and sigma . 1.0, Po . 3.9 X 10(-4) cm/s, and Km . 30 mM for ethylene glycol. The effects of the inhibitors copper, phloretin, p-chloromercuriphenylsulfonate, and 5,5'-dithiobis (2-nitro) benzoic acid on the urea, ethylene glycol, and water permeability were determined. The results suggest that there are three separate, independent transport systems: one for water, one for urea and related compounds, and one for ethylene glycol and glycerol.

Levitt, D.G.; Mlekoday, H.J.

1983-02-01

302

Determination of negative permeability and permittivity of metal strip coated ferrite disks using the transmission and reflection technique  

NASA Astrophysics Data System (ADS)

In this paper, a full band microwave isolator constructed from an array of metal wire-coated ferrite samples is presented. Here, the magnetic permeability of the metamaterialized structure is controlled by a relatively weak external magnetic field. The tunable permeability of the ferrites in this experiment allows us to create unidirectional wave propagation through the structure over the entire X-band frequency spectrum. The analysis presented here takes into account potential surface plasmon modes generated between the gaps of metal wires when the external magnetic field is applied. Here, we present a modification of the traditional transmission-reflection measurement method by normalizing the transmission and reflection coefficients. This modification removes the occurrence of atypical phenomena for negative imaginary components of permeability and permittivity that arises in the measurement of metamaterials. Our modified method precisely determines the refractive index, impedance, permittivity, and permeability of both traditional reciprocal networks as well as nonreciprocal networks, such as the one presented here.

Rahman, N.; Obol, M.; Sharma, A.; Afsar, M. N.

2010-05-01

303

Permeability evolution in carbonate fractures: Competing roles of confining stress and fluid pH  

NASA Astrophysics Data System (ADS)

We explore the permeability evolution of fractures in carbonate rock that results from the effects of mechanical stress and nonequilibrium chemistry (pH of fluid). Core plugs of Capitan limestone are saw cut to form a smooth axial fracture that is subsequently roughened to simulate a natural fracture with controlled surface topography. Aqueous solutions of ammonium chloride (pH 5˜7) transit these plugs at confining stresses of 3-10 MPa, with flow rates and mineral mass fluxes measured to constrain competing mechanisms of permeability evolution. The effluent calcium concentrations are always much lower than equilibrium calcium solubility, resulting in the dissolution-dominant permeability evolution in our experiments. Depending on the combination of confining stress and fluid pH, the fracture apertures either gape (permeability increase) or close (permeability reduction). We quantitatively constrain the transition between gaping (pH < 6.1) and closing (pH > 6.5) with this transition independent of confining stress up to 10 MPa. A transitional regime (6.1 < pH < 6.5) of invariant aperture represents a balance between the two mechanisms of free-face dissolution and pressure solution at the bridging asperities. We employ a lumped-parameter model to interpret the dissolution-dominant evolution of permeability. By considering different dissolution rate constants between noncontacting asperities and the stagnant water film at the contacting asperities, this model replicates the principal characteristics of permeability evolution of the fracture. Observed rates of aperture change are ill matched when the influent pH is 5-6, since wormhole formation is not accommodated in the model. These observations offer a promising pathway to index the switch from aperture gaping to aperture closing for reactive flow as reactivity is reduced and stress effects become more important.

Ishibashi, Takuya; McGuire, Thomas P.; Watanabe, Noriaki; Tsuchiya, Noriyoshi; Elsworth, Derek

2013-05-01

304

Nanoparticle Diffusion Measures Bulk Clot Permeability  

PubMed Central

A clot's function is to achieve hemostasis by resisting fluid flow. Permeability is the measurement of a clot's hemostatic potential. It is sensitive to a wide range of biochemical parameters and pathologies. In this work, we consider the hydrodynamic phenomenon that reduces the mobility of fluid near the fiber surfaces. This no-slip boundary condition both defines the gel's permeability and suppresses nanoparticle diffusion in gel interstices. Here we report that, unlike previous work where steric effects also hindered diffusion, our system—nanoparticles in fibrin gel—was subject exclusively to hydrodynamic diffusion suppression. This result enabled an automated, high-throughput permeability assay that used small clot volumes. Permeability was derived from nanoparticle diffusion using the effective medium theory, and showed one-to-one correlation with measured permeability. This technique measured permeability without quantifying gel structure, and may therefore prove useful for characterizing similar materials (e.g., extracellular matrix) where structure is uncontrolled during polymerization and difficult to measure subsequently. We also report that PEGylation reduced, but did not eliminate, the population of immobile particles. We studied the forces required to pull stuck PEG particles free to confirm that the attachment is a result of neither covalent nor strong electrostatic binding, and discuss the relevance of this force scale to particle transport through physiological clots. PMID:21843486

Spero, Richard Chasen; Sircar, Rachel K.; Schubert, Ryan; Taylor, Russell M.; Wolberg, Alisa S.; Superfine, Richard

2011-01-01

305

Comparative field permeability measurement of permeable pavements using ASTM C1701 and NCAT permeameter methods.  

PubMed

Fully permeable pavement is gradually gaining support as an alternative best management practice (BMP) for stormwater runoff management. As the use of these pavements increases, a definitive test method is needed to measure hydraulic performance and to evaluate clogging, both for performance studies and for assessment of permeability for construction quality assurance and maintenance needs assessment. Two of the most commonly used permeability measurement tests for porous asphalt and pervious concrete are the National Center for Asphalt Technology (NCAT) permeameter and ASTM C1701, respectively. This study was undertaken to compare measured values for both methods in the field on a variety of permeable pavements used in current practice. The field measurements were performed using six experimental section designs with different permeable pavement surface types including pervious concrete, porous asphalt and permeable interlocking concrete pavers. Multiple measurements were performed at five locations on each pavement test section. The results showed that: (i) silicone gel is a superior sealing material to prevent water leakage compared with conventional plumbing putty; (ii) both methods (NCAT and ASTM) can effectively be used to measure the permeability of all pavement types and the surface material type will not impact the measurement precision; (iii) the permeability values measured with the ASTM method were 50-90% (75% on average) lower than those measured with the NCAT method; (iv) the larger permeameter cylinder diameter used in the ASTM method improved the reliability and reduced the variability of the measured permeability. PMID:23434738

Li, Hui; Kayhanian, Masoud; Harvey, John T

2013-03-30

306

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

307

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.; Chalé, 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

308

Thermal analysis of vascular reactivity  

E-print Network

dysfunction. Given the promising nature of thermal monitoring to study VR, this thesis focuses on the analysis of the underlying physics affecting fingertip temperature during vascular occlusion and subsequent hyperemia. I will quantify the contribution...

Deshpande, Chinmay Vishwas

2009-05-15

309

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

310

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

311

DPIV Measurements of Vortex Ring Interaction with Multiple Permeable Screens  

NASA Astrophysics Data System (ADS)

Flow visualization of the interaction of a vortex ring impinging on several parallel, transparent permeable screens was made previously for screens with 84% open area ratio. The results indicated the vortex ring split into smaller vortical structures after its interaction with the first screen and exhibited a continuous break down into increasingly irregular flow after interaction with subsequent screens. The flow did not reorganize into a transmitted vortex ring as was observed with vortex rings impinging on a single permeable screen. The present work seeks to provide a more quantitative assessment of the flow through screens using DPIV. DPIV measurements were made using an aqueous solution that was refractive index matched to the transparent screens. Measurements were made for vortex rings interacting with screens with variable spacing and open area ratios of 58%-84%. The vortex rings were generated with a piston-cylinder vortex ring generator using piston stroke-to-diameter ratios of 2-4 and jet Reynolds numbers of 1000-2000. Preliminary results show splitting and decay of the flow vorticity in agreement with the flow visualization.

Musta, Mustafa N.; Krueger, Paul S.

2009-11-01

312

Vascular Ehlers–Danlos syndrome  

Microsoft Academic Search

Vascular Ehlers–Danlos syndrome, also known as Ehlers–Danlos syndrome type IV, is a life-threatening inherited disorder of connective tissue, resulting from mutations in the COL3A1 gene coding for type III procollagen. Vascular EDS causes severe fragility of connective tissues with arterial and gastrointestinal rupture, and complications of surgical and radiological interventions. As for many rare orphan diseases, delay in diagnosis is

Dominique P Germain; Yessica Herrera-Guzman

2004-01-01

313

Vascular lesions of the hand.  

PubMed

The vascular malformations are not uncommon on the hand and offer diagnostic and therapeutic challenges. Enjolras and Mulliken's classification is exposed. Their depiction and pretreatment assessment may benefit from non-invasive imaging as color-Doppler ultrasound and MRI combined with magnetic resonance angiography (MRA). Some chronic traumatic vascular injuries as the hypothenar hammer syndrome may also take advantage of these imaging modalities. PMID:16298677

Drapé, Jean-Luc; Feydy, Antoine; Guerini, Henri; Desmarais, Eric; Godefroy, Didier; Le Viet, Dominique; Chevrot, Alain

2005-12-01

314

Anti-YKL-40 antibody and ionizing irradiation synergistically inhibit tumor vascularization and malignancy in glioblastoma.  

PubMed

Chemo/radiotherapies are the most common adjuvant modality treated for patients with glioblastoma (GBM) following surgery. However, the overall therapeutic benefits are still uncertain, as the mortality remains high. Elevated expression of YKL-40 in GBM was correlated with increases in mural cell-associated vessel coverage, stability and density, and decreases in vessel permeability and disease survival. To explore the potential role of YKL-40 in mural cell-mediated tumor vascularization, we employed an anti-YKL-40 neutralizing antibody (mAY) and ionizing irradiation (IR) in xenografted brain tumor models. Although single treatment with mAY or IR partially increased mouse survival, their combination led to dramatic inhibition in tumor growth and increases in mouse survival. mAY blocked mural cell-mediated vascular stability, integrity and angiogenesis; whereas IR merely promoted tumor cell and vascular cell apoptosis. Vascular radioresistance is at least partially attributed to expression of YKL-40 in mural cells. These divergent effects were also recapitulated in cultured systems using endothelial cells and mural cells differentiated from glioblastoma stem-like cells (GSCs). Dysfunction of intercellular contact N-cadherin was found to mediate mAY-inhibited vascularization. Collectively, the data suggest that the conjunction therapy with mAY and IR synergistically inhibit tumor vascularization and progression. The evidence may shed light on a new adjuvant therapy in clinic. PMID:24282289

Shao, Rong; Francescone, Ralph; Ngernyuang, Nipaporn; Bentley, Brooke; Taylor, Sherry L; Moral, Luis; Yan, Wei

2014-02-01

315

A Novel Vascular Homing Peptide Strategy to Selectively Enhance Pulmonary Drug Efficacy in Pulmonary Arterial Hypertension  

PubMed Central

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

2015-01-01

316

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

317

The effects of heparin and related molecules on vascular permeability and neutrophil accumulation in rabbit skin  

PubMed Central

Unfractionated heparin (UH) has been shown to possess a wide range of properties which are potentially anti-inflammatory. Many of these studies, including effects of heparin on adhesion of inflammatory cells to endothelium, have been carried out in vitro. In the present study, we have used radioisotopic techniques to study the effect of UH, and related molecules, on in vivo inflammatory responses (plasma exudation (PE) and PMN accumulation) in rabbit skin induced by cationic proteins, mediators and antigen. Intradermal (i.d.) pretreatment with UH dose-dependently inhibited poly-L-lysine (PLL)-induced responses. The same treatment had no effect on antigen (extract of Alternaria tenuis, AT)-, formyl-methionyl-leucyl-phenylalanine (fMLP)- or leukotriene (LT) B4-induced responses, although i.d. dextran sulphate (DS) significantly inhibited responses to all of these mediators. High dose (10,000?u?kg?1) intravenous UH significantly decreased cutaneous responses to fMLP and LTB4. By comparison, the selectin inhibitor, fucoidin, and DS, were very effective inhibitors of these responses, and of responses to AT and PLL. In contrast to the weak effect in the in vivo studies, UH significantly inhibited in vitro homotypic aggregation of rabbit PMNs, showing that it can modify PMN function. Our data with i.d. UH confirm the important ability of this molecule to interact with and neutralize polycationic peptides in vivo, suggesting that this is a prime role of endogenous heparin. The lack of effect of exogenous heparin on acute inflammatory responses induced by allergen, suggests that cationic proteins are unlikely to be primary mediators of the allergen-induced PE or PMN accumulation. PMID:11815383

Jones, Helen; Paul, William; Page, Clive P

2002-01-01

318

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

319

Index Funds Online  

NSDL National Science Digital Library

Matthew Roberts recently released Index Funds Online in response to the lack of index investment fund information on the Internet. Site features include the market performance newsletter Indexing Quarterly, background and definitional information on major US Indexes such as the S&P 500, and a library of new and interesting financial Websites, articles, and book reviews. Links to current index performance figures are also provided as well as a simple site search system and index fund discussion board.

320

Numerical study of electromagnetic waves interacting with negative index materials.  

PubMed

We study numerically the electromagnetic scattering properties of structures with negative indices of refraction. To perform this analysis, we utilize a commercial finite-element based electromagnetic solver (HFSS, Ansoft), in which a negative index material can be formed from mesh elements whose permittivity and permeability are both negative. In particular, we investigate the expected transmission characteristics of a finite beam incident on negative index prisms and lenses. We also confirm numerically the predicted superlens effect of an image formed by a planar slab with index n=-1, using two subwavelength (ë/20) slits as objects. PMID:19461776

Kolinko, Pavel; Smith, David

2003-04-01

321

Vascular access today  

PubMed Central

The number of patients with chronic kidney disease requiring renal replacement therapy has increased worldwide. The most common replacement therapy is hemodialysis (HD). Vascular access (VA) has a key role for successful treatment. Despite the advances that have taken place in the field of the HD procedure, few things have changed with regards to VA in recent years. Arteriovenous fistula (AVF), polytetrafluoroethylene graft and the cuffed double lumen silicone catheter are the most common used for VA. In the long term, a number of complications may present and more than one VA is needed during the HD life. The most common complications for all of VA types are thrombosis, bleeding and infection, the most common cause of morbidity in these patients. It has been estimated that VA dysfunction is responsible for 20% of all hospitalizations. The annual cost of placing and looking after dialysis VA in the United States exceeds 1 billion dollars per year. A good functional access is also vital in order to deliver adequate HD therapy. It seems that the native AVF that Brescia and Cimino described in 1966 still remains the first choice for VA. The native forearm AVFs have the longest survival and require the fewest interventions. For this reason, the forearm AVF is the first choice, followed by the upper-arm AVF, the arteriovenous graft and the cuffed central venous catheter is the final choice. In conclusion, VA remains the most important issue for patients on HD and despite the technical improvements, a number of problems and complications have to be resolved. PMID:24175244

Pantelias, Konstantinos; Grapsa, Eirini

2012-01-01

322

A potential role for reactive oxygen species and the HIF-1?-VEGF pathway in hypoxia-induced pulmonary vascular leak  

PubMed Central

Acute hypoxia causes pulmonary vascular leak and is involved in the pathogenesis of pulmonary edema associated with inflammation, acute altitude exposure, and other critical illnesses. Reactive oxygen species, HIF-1 and VEGF have all been implicated in various hypoxic pathologies, yet the ROS-HIF-1-VEGF pathway in pulmonary vascular leak has not been defined. We hypothesized that the ROS-HIF-1-VEGF pathway has an important role in producing hypoxia-induced pulmonary vascular leak. Human pulmonary artery endothelial cell monolayers (HPAEC) were exposed to either normoxia (21% O2) or acute hypoxia (3% O2) for 24 h and monolayer permeability, H2O2, nuclear HIF-1?, and cytosolic VEGF were determined. HPAEC were treated with antioxidant cocktail (AO: ascorbate, glutathione, and ?-tocopherol), HIF-1 siRNA, or VEGF soluble binding protein (sFlt-1) to delineate the role of the ROS-HIF-1-VEGF pathway in hypoxia-induced HPAEC leak. Additionally, mice exposed to hypobaric hypoxia (18,000 ft, 10% O2) were treated with the same antioxidant to determine if in-vitro responses corresponded to in-vivo hypoxia stress. Hypoxia increased albumin permeability, H2O2 production, nuclear HIF-1?, and cytosolic VEGF concentration. Treatment with an AO lowered the hypoxia-induced HPAEC monolayer permeability as well as elevation of HIF-1? and VEGF. Treatment of hypoxia-induced HPAEC with either a siRNA designed against HIF-1? or VEGF antagonist soluble fms-like tyrosine kinase (sFlt)-1 decreased monolayer permeability. Mice treated with AO and exposed to hypobaric hypoxia (18,000 ft, 10% O2) had less pulmonary vascular leak than those that were untreated. Our data suggest that hypoxia-induced permeability is due, in part, to the ROS-HIF-1?-VEGF pathway. PMID:19358884

Irwin, David C.; McCord, Joe. M.; Nozik-Grayck, Eva; Beckly, Ginny; Foreman, Ben; Sullivan, Tim.; White, Molly; Crossno, Joseph T; Bailey, Damian; Flores, Sonia C.; Majka, Susan; Klemm, Dwight; TissotvanPatot, Martha C.

2009-01-01

323

Analysis of Basis Weight Uniformity of Microfiber Nonwovens and Its Impact on Permeability and Filtration Properties  

NASA Astrophysics Data System (ADS)

It is widely recognized that nonwoven basis weight non-uniformity affects various properties of nonwovens. However, few studies can be found in this topic. The development of uniformity definition and measurement methods and the study of their impact on various web properties such as filtration properties and air permeability would be beneficial both in industrial applications and in academia. They can be utilized as a quality control tool and would provide insights about nonwoven behaviors that cannot be solely explained by average values. Therefore, for quantifying nonwoven web basis weight uniformity we purse to develop an optical analytical tool. The quadrant method and clustering analysis was utilized in an image analysis scheme to help define "uniformity" and its spatial variation. Implementing the quadrant method in an image analysis system allows the establishment of a uniformity index that can be used to quantify the degree of uniformity. Clustering analysis has also been modified and verified using uniform and random simulated images with known parameters. Number of clusters and cluster properties such as cluster size, member and density was determined. We also utilized this new measurement method to evaluate uniformity of nonwovens produced with different processes and investigated impacts of uniformity on filtration and permeability. The results of quadrant method shows that uniformity index computed from quadrant method demonstrate a good range for non-uniformity of nonwoven webs. Clustering analysis is also been applied on reference nonwoven with known visual uniformity. From clustering analysis results, cluster size is promising to be used as uniformity parameter. It is been shown that non-uniform nonwovens has provide lager cluster size than uniform nonwovens. It was been tried to find a relationship between web properties and uniformity index (as a web characteristic). To achieve this, filtration properties, air permeability, solidity and uniformity index of meltblown and spunbond samples was measured. Results for filtration test show some deviation between theoretical and experimental filtration efficiency by considering different types of fiber diameter. This deviation can occur due to variation in basis weight non-uniformity. So an appropriate theory is required to predict the variation of filtration efficiency with respect to non-uniformity of nonwoven filter media. And the results for air permeability test showed that uniformity index determined by quadrant method and measured properties have some relationship. In the other word, air permeability decreases as uniformity index on nonwoven web increase.

Amirnasr, Elham

324

Lung vascular injury with protease infusion. Relationship to plasma fibronectin.  

PubMed Central

Fibronectin exists in a soluble form in plasma and in an insoluble form in tissues. Plasma fibronectin can modulate phagocytic function as well as incorporate into the tissue matrix where it is believed to influence microvascular integrity and tissue repair. The temporal alterations in plasma and lung lymph fibronectin were studied in relation to increased pulmonary vascular permeability induced by protease infusion. The acute sheep lung lymph fistula model was used. A 39% decrease in plasma fibronectin (control = 421 +/- 67 micrograms/ml) was observed 2.5 hours (255 +/- 43 micrograms/ml) after protease infusion. There was an elevation of lymph fibronectin early after protease infusion, followed by a progressive decline. Concomitant with the decrease in plasma fibronectin, an increase in lymph flow (QL) of greater than 200% (from a control of 6.7 +/- 1.0 ml/hr to 13.9 +/- 1.4 ml/hr) was observed within 2.5 hours. Also, there was a sustained elevation in the total protein lymph/plasma concentration (L/P) ratio, which was maximal at 2.5 hours. The transvascular protein clearance (TVPC = QL X L/P) was 4.5 +/- 0.7 ml/hr at the control period and 13.1 +/- 2.0 ml/hr by 2.5 hours. This was indicative of increased flux of protein-rich fluid across the pulmonary endothelial barrier. Lung vascular permeability stabilized after 2.5 hours as manifested by a slowly declining L/P ratio. Thus, plasma fibronectin deficiency may contribute to the etiology of increased lung vascular permeability with protease infusion. Since the progressive decline in plasma fibronectin was not reflected in a proportional increase in lymph fibronectin, plasma fibronectin may have sequestered in tissues such as the lung, or perhaps in reticuloendothelial cells during the injury phase. Whether the progressive decrease in plasma fibronectin reflects its incorporation into the endothelial barrier matrix where it may mediate stabilization of the pulmonary microvascular barrier remains to be determined. PMID:4015230

Cohler, L F; Saba, T M; Lewis, E P

1985-01-01

325

Transport in Cement:Transport in Cement: Relating Permeability and PoreRelating Permeability and Pore  

E-print Network

Transport in Cement:Transport in Cement: Relating Permeability and PoreRelating Permeability, 2004 #12;OutlineOutline Cement Manufacturing and StructureCement Manufacturing and Structure ofofCalcinated in rotaryin rotary kiln at 1500 C for 30kiln at 1500 C for 30-- 40 minutes40 minutes Produces Cement

Petta, Jason

326

Gastrointestinal permeability in patients with irritable bowel syndrome assessed using a four probe permeability solution  

PubMed Central

Background Abnormal gastrointestinal permeability has been linked to irritable bowel syndrome (IBS). The lactulose-to-mannitol ratio is traditionally used to assess small intestine permeability while sucralose and sucrose are used to assess colonic and gastric permeability respectively. We used a single 4-probe test solution to assess permeability throughout the gastrointestinal tract in IBS patients and healthy controls by measuring the recovery of the probes in urine after ingestion using a modified liquid chromatography mass spectrometry protocol. Methods Fasting participants (N = 59) drank a permeability test solution (100 ml: sucralose, sucrose, mannitol, and lactulose). Urine was collected over a 5-h period and kept frozen until analysis. Urinary sugar concentrations were measured using an liquid chromatography/triple quadruple mass spectrometer. Results Colonic permeability was significantly lower in IBS patients when compared to healthy controls (p = 0.011). Gastric and small intestinal permeability did not significantly differ between the groups. Conclusions The study demonstrates the clinical potential of this non-invasive method for assessing alterations in gastrointestinal permeability in patients with IBS. PMID:23328210

Del Valle-Pinero, Arseima Y.; Van Deventer, Hendrick E.; Fourie, Nicolaas H.; Martino, Angela C.; Patel, Nayan S.; Remaley, Alan T.; Henderson, Wendy A.

2013-01-01

327

Early experience on peripheral vascular application of the vascular plugs  

PubMed Central

Background Transcatheter closure of various congenital and acquired vascular malformations with Amplatzer Vascular plugs I and II has been established. Here we present our experience with device closure. Materials and methods Between October 2006 and August 2012, nine (three males and six females) patients aged between 11 months and 62 years (mean age 19 years) underwent percutaneous device closure with AVP I and II vascular plugs for congenital and acquired arteriovenous malformation and cardiac diverticulum are presented here. Results One case of coronary cameral fistula, four cases of pulmonary arteriovenous fistula, one case of large major aortopulmonary collaterals (in tetralogy of Fallot closed before intracardiac repair), one case of congenital cardiac diverticulum, one case of fistula between external carotid artery and internal jugular vein and one case of iatrogenic carotid jugular fistula were successfully closed with AVP I and II plugs. Overall in nine cases, 16 AVP I and II plugs were deployed to occlude feeding vessels and one cardiac diverticulum. The technical success rate was 100%. No major complications were observed. Conclusion Amplatzer vascular plugs can be used successfully for closure of various congenital and acquired vascular malformations with good result. PMID:24206877

Rohit, Manoj Kumar; Sinha, Alok Kumar; Kamana, Naveen Krishna

2013-01-01

328

Continental Portuguese Territory Flood Susceptibility Index - contribution for a vulnerability index  

NASA Astrophysics Data System (ADS)

This work defines a national flood susceptibility index for the Portuguese continental territory, by proposing the aggregation of different variables which represent natural conditions for permeability, runoff and accumulation. This index is part of the national vulnerability index developed in the scope of Flood Maps in Climate Change Scenarios (CIRAC) project, supported by the Portuguese Association of Insurers (APS). This approach expands on previous works by trying to bridge the gap between different floods mechanisms (e.g. progressive and flash floods) occurring at different spatial scales in the Portuguese territory through: (a) selecting homogeneously processed datasets, (b) aggregating their values to better translate the spatially continuous and cumulative influence in floods at multiple spatial scales. Results show a good ability to capture, in the higher susceptibility classes, different flood types: progressive floods and flash floods. Lower values are usually related to: mountainous areas, low water accumulation potential and more permeable soils. Validation with independent flood datasets confirmed these index characteristics, although some overestimation can be seen in the southern region of Alentejo where, due to a dense hydrographic network and an overall low slope, floods are not as frequent as a result of lower precipitation mean values. Future work will focus on: (i) including extreme precipitation datasets to represent the triggering factor, (ii) improving representation of smaller and stepper basins, (iii) optimizing variable weight definition process, (iii) developing more robust independent flood validation datasets.

Jacinto, R.; Grosso, N.; Reis, E.; Dias, L.; Santos, F. D.; Garrett, P.

2014-12-01

329

Honeycomb Core Permeability Under Mechanical Loads  

NASA Technical Reports Server (NTRS)

A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

1997-01-01

330

Tools for Printing Indexes  

Microsoft Academic Search

SUMMARY This paper describes a set of programs for processing and printing the index for a book or a manual. The input consists of lines containing index terms and page numbers. The programs collect multiple occurrences of the same terms, compress runs of page numbers, create permutations (e.g., 'index, book' from 'book index'), and sort them into proper alphabetic order.

Jon Louis Bentley; Brian W. Kernighan

1988-01-01

331

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

332

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

333

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

334

Quaker Resources Online Index.  

ERIC Educational Resources Information Center

The Quaker Resources Online Index is a World Wide Web-based index, including author, title, subject, and meeting indexes, that provides access to Quaker materials available on the Web. Given the current failings and shortcomings of search engines and automated key word searches, this index brings together information from a variety of sources and…

Beke-Harrigan, Heidi

335

The role of guanylyl cyclases in the permeability response to inflammatory mediators in pial venular capillaries in the rat  

PubMed Central

Inflammatory mediators have a role in the formation of cerebral oedema and there is evidence that cGMP is an important signal in vascular permeability increase. We have investigated the role and the source of cGMP in mediating the permeability response to acutely applied bradykinin and the histamine H2 agonist dimaprit on single cerebral venular capillaries, by using the single vessel occlusion technique. We found that 8-bromo-cGMP applied acutely resulted in a small and reversible permeability increase with a log EC50 ?7.2 ± 0.15 m. KT 5823, the inhibitor of cGMP-dependent protein kinase, abolished the permeability responses to both bradykinin and dimaprit, while zaprinast, an inhibitor of type 5 phosphodiesterase, potentiated the response to bradykinin. On the other hand, l-NMMA blocked the response to dimaprit, but not that to bradykinin. Inhibitors of soluble guanylyl cyclase, LY 85353 and methylene blue, also inhibited the permeability response to dimaprit, but not bradykinin. The permeability responses to the natriuretic peptides ANP and CNP were of similar magnitude to that of bradykinin with log EC50 ?10.0 ± 0.33 m and ?8.7 ± 0.23 m, respectively. The natriuretic peptide receptor antagonist HS-142–1 blocked permeability responses to bradykinin as well as to ANP, and leukotriene D4 blocked the responses to CNP and bradykinin, but not to dimaprit. In conclusion, the histamine H2 receptor appears to signal via cGMP that is generated by a NO and soluble guanylyl cyclase, while bradykinin B2 receptor also signals via cGMP but through particulate guanylyl cyclase. PMID:11927680

Sarker, M H; Fraser, P A

2002-01-01

336

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...

337

Dysfunction of vascular smooth muscle and vascular remodeling by simvastatin.  

PubMed

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, are widely prescribed for hypercholesterolemia. With the increasing use of statins, numerous reports demonstrated that statins can cause damage to skeletal muscles. However, the toxicities of statins on vascular smooth muscle, which are essential to cardiovascular homeostasis, have not been previously described. Here, we examined the effects of simvastatin on the contractile function and the integrity of vascular smooth muscle in isolated rat thoracic aortic rings, primary cultured vascular smooth muscle cells (VSMCs) in vitro and rats in vivo. In aortic rings, simvastatin suppressed the normal agonist-induced contractile responses in time- and concentration-dependent manners (0.86 g ± 0.11 at 10 ?M simvastatin for 24 h compared with 1.89 g ± 0.11 at control). The suppression persisted in the endothelium-denuded aortic rings and was irreversible even after wash-out of simvastatin. Simvastatin suppressed the contraction induced by Bay K8644, an activator of voltage-operated Ca²? channel (VOCC) in rat aortic rings and abolished agonist-induced intracellular Ca²? increase in VSMCs. The simvastatin-induced contractile dysfunction was reversed by the supplementation of mevalonate and geranylgeranylpyrophosphate, precursors for protein isoprenylation. Consistently, activation of RhoA, a representative isoprenylated protein, was disrupted by simvastatin in VSMCs and RhoA-mediated phosphorylation of MYPT1 and CPI-17, and tonic tension were also suppressed. Notably, prolonged treatment of simvastatin up to 48 h induced apoptosis of vascular smooth muscle in aortic rings. Most importantly, simvastatin treatment in vivo significantly attenuated the agonist-induced vasoconstriction in rats ex vivo and induced a decrease in luminal area of the vascular wall. Collectively, these results demonstrate that simvastatin can impair the normal vascular contractility by disturbing Ca²? influx and RhoA activity, ultimately leading to apoptosis and structural remodeling. PMID:24449418

Kang, Seojin; Woo, Hyang-Hwa; Kim, Keunyoung; Lim, Kyung-Min; Noh, Ji-Yoon; Lee, Moo-Yeol; Bae, Young Min; Bae, Ok-Nam; Chung, Jin-Ho

2014-04-01

338

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

339

Vascular casting for the study of vascular morphogenesis.  

PubMed

Microvascularity and angiogenesis play a pivotal role during normal growth and in a variety of pathological conditions such as inflammation, tumor growth, macular degeneration, and tissue regeneration. Vascular corrosion casting has been established as a method to analyze and evaluate two- and three-dimensionally the morphology and architecture of blood vessels of organs and tissues, such as tumors, brains, embryos, or the chorioallantoic membrane. Microvascular casts may be further dissected for visualizing and quantifying vascular morphology using scanning electron microscopy (SEM), micro computed tomographic (?CT) imaging, or synchrotron radiation-based micro computed tomographic (SR?CT) imaging. PMID:25468599

Ackermann, Maximilian; Konerding, Moritz A

2015-01-01

340

Water Permeability of Thin Lipid Membranes  

PubMed Central

The osmotic permeability coefficient, Pf, and the tagged water permeability coefficient, Pd, were determined for thin (<100 A) lipid membranes formed from ox brain lipids plus DL-?-tocopherol; their value of approximately 1 x 10-3 cm/sec is within the range reported for plasma membranes. It was established that Pf = Pd. Other reports that Pf > Pd can be attributed to the presence of unstirred layers in the experimental determination of Pd. Thus, there is no evidence for the existence of aqueous pores in these thin phospholipid membranes. The adsorption onto the membrane of a protein that lowers its electrical resistance by a factor of 103 was found not to affect its water permeability; however, glucose and sucrose were found to interact with the membrane to modify Pf. Possible mechanisms of water transport across these films are discussed, together with the implications of data obtained on these structures for plasma membranes. PMID:6034767

Cass, Albert; Finkelstein, Alan

1967-01-01

341

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

342

GROUNDWATER FLOW IN LOW-PERMEABILITY ENVIRONMENTS.  

USGS Publications Warehouse

Certain geologic media are known to have small permeability; subsurface environments composed of these media and lacking well developed secondary permeability have groundwater flow systems with many distinctive characteristics. Moreover, groundwater flow in these environments appears to influence the evolution of certain hydrologic, geologic, and geochemical systems, may affect the accumulation of petroleum and ores, and probably has a role in the structural evolution of parts of the crust. Such environments are also important in the context of waste disposal. This review attempts to synthesize the diverse contributions of various disciplines to the problem of flow in low-permeability environments. Problems hindering analysis are enumerated together with suggested approaches to overcoming them. A common thread running through the discussion is the significance of size- and time-scale limitations of the ability to directly observe flow behavior and make significance of size- and time-scale limitations of the ability to directly observe flow behavior and make measurements of parameters.

Neuzil, C.E.

1986-01-01

343

Interstitial Fluid Flow and Drug Delivery in Vascularized Tumors: A Computational Model  

PubMed Central

Interstitial fluid is a solution that bathes and surrounds the human cells and provides them with nutrients and a way of waste removal. It is generally believed that elevated tumor interstitial fluid pressure (IFP) is partly responsible for the poor penetration and distribution of therapeutic agents in solid tumors, but the complex interplay of extravasation, permeabilities, vascular heterogeneities and diffusive and convective drug transport remains poorly understood. Here we consider–with the help of a theoretical model–the tumor IFP, interstitial fluid flow (IFF) and its impact upon drug delivery within tumor depending on biophysical determinants such as vessel network morphology, permeabilities and diffusive vs. convective transport. We developed a vascular tumor growth model, including vessel co-option, regression, and angiogenesis, that we extend here by the interstitium (represented by a porous medium obeying Darcy's law) and sources (vessels) and sinks (lymphatics) for IFF. With it we compute the spatial variation of the IFP and IFF and determine its correlation with the vascular network morphology and physiological parameters like vessel wall permeability, tissue conductivity, distribution of lymphatics etc. We find that an increased vascular wall conductivity together with a reduction of lymph function leads to increased tumor IFP, but also that the latter does not necessarily imply a decreased extravasation rate: Generally the IF flow rate is positively correlated with the various conductivities in the system. The IFF field is then used to determine the drug distribution after an injection via a convection diffusion reaction equation for intra- and extracellular concentrations with parameters guided by experimental data for the drug Doxorubicin. We observe that the interplay of convective and diffusive drug transport can lead to quite unexpected effects in the presence of a heterogeneous, compartmentalized vasculature. Finally we discuss various strategies to increase drug exposure time of tumor cells. PMID:23940570

Welter, Michael; Rieger, Heiko

2013-01-01

344

Development of an Improved Permeability Modification Simulator  

SciTech Connect

This report describes the development of an improved permeability modification simulator performed jointly by BDM Petroleum Technologies and Schlumberger Dowell under a cooperative research and development agreement (CRADA) with the US Department of Energy. The improved simulator was developed by modifying NIPER's PC-GEL permeability modification simulator to include a radial model, a thermal energy equation, a wellbore simulator, and a fully implicit time-stepping option. The temperature-dependent gelation kinetics of a delayed gel system (DGS) is also included in the simulator.

Gao, H.W.; Elphnick, J.

1999-03-09

345

Differential Apicobasal VEGF Signaling at Vascular Blood-Neural Barriers  

PubMed Central

Summary 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

2014-01-01

346

Gastro-intestinal vascular emergencies.  

PubMed

Gastro-Intestinal Vascular Emergencies include all digestive ischaemic injuries related to acute or chronic vascular and/or haemodynamic diseases. Gastro-intestinal ischaemic injuries can be occlusive or non-occlusive, arterial or venous, localized or generalized, superficial or transmural and share the risks of infarction, organ failure and death. The diagnosis must be suspected, at the initial presentation of any sudden, continuous and unusual abdominal pain, contrasting with normal physical examination. Risk factors are often unknown at presentation and no biomarker is currently available. The diagnosis is confirmed by abdominal computed tomography angiography identifying intestinal ischaemic injury, either with vascular occlusion or in a context of low flow. Recent knowledge in the pathophysiology of acute mesenteric ischaemia, clinical experience and existing recommendations have generated a multimodal and multidisciplinary management strategy. Based on the gastro-intestinal viability around a simple algorithm, and coordinated by gastroenterologists, the dual aim is to avoid large intestinal resections and death. PMID:24160929

Corcos, Olivier; Nuzzo, Alexandre

2013-10-01

347

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

348

Three-dimensional human arterial wall models for in vitro permeability assessment of drug and nanocarriers.  

PubMed

Monolayers of endothelial cells (1L-ECs) have been generally used as in vitro vascular wall models to study the vascular mechanisms and transport of substances. However, these two-dimensional (2D-) system cannot represent the properties of native vascular walls which have a 3D-structure and are composed of not only ECs, but also smooth muscle cells (SMCs) and other surrounding tissues. Here in, 5-layered (5L) 3D-arterial wall models (5L-AWMs) composed of EC monolayer and 4-layered SMCs were constructed by hierarchical cell manipulation. We applied the 5L-AWMs to evaluate their barrier function and permeability to nano-materials in order to analyze drug, or drug nanocarrier permeability to the blood vessel in vitro. Barrier property of the 3D-AWMs was confirmed by Zonula occludens (ZO-1) staining and their transendothelial electrical resistance (TEER), which was comparable to 1L-ECs, while the SMCs showed close to zero. The effect of substance size to permeability across the 5L-AWMs was clearly observed from dextrans with various molecular weights, which agreed well with the known phenomena of the in vivo blood vessels. Importantly, transport of nano-materials could be observed across the depth of 5L-AWMs, suggesting the advantage of 3D-AWMs over general 2D-systems. By using this system, we evaluate the transport of 35nm phenylalanine-modified poly(?-Glutamic Acid) nanoparticles (?-PGA-Phe NPs) as a candidate of biodegradable drug carrier. Interestingly, despite of having comparable size to dextran-2000k (28nm), the ?-PGA-Phe NPs distinctly showed approximately 20 times faster transport across the 5L-AWMs, suggesting the effect of intrinsic properties of the substance on the transport. This in vitro evaluation system using the 3D-AWMs is therefore useful for the design and development of nano-drug carriers for treatment of vascular diseases, such as atherosclerosis. PMID:25475732

Chetprayoon, Paninee; Matsusaki, Michiya; Akashi, Mitsuru

2015-01-01

349

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

Martínez-Navarro, Angélica C.; Galván-Gordillo, Santiago V.; Xoconostle-Cázares, Beatriz; Ruiz-Medrano, Roberto

2013-01-01

350

Production of Soluble Human Vascular Endothelial Growth Factor VEGF-A165-Heparin Binding Domain in Escherichia coli  

PubMed Central

We report a method for production of soluble heparin binding domain (HBD) of human vascular endothelial growth factor VEGF-A165. Recombinant VEGF-A165-HBD that contains four disulphide bridges was expressed in specialised E. coli SHuffle cells and its activity has been confirmed through interactions with neuropilin and heparin. The ability to produce significant quantities of a soluble active form of VEGF-A165-HBD will enable further studies addressing the role of VEGF-A in essential processes such as angiogenesis, vasculogenesis and vascular permeability. PMID:23409021

Seyedarabi, Arefeh; Cheng, Lili; Zachary, Ian; Djordjevic, Snezana

2013-01-01

351

What the Index Medicus Indexes, and Why *  

PubMed Central

The main criterion for selecting journals for indexing in Index Medicus, and thereby largely in MEDLARS, is quality. Subject scope varies with the voiced needs of the biomedical community. The Index aims to cover the best journals in all relevant subject fields, but the percentage of journals on a subject indexed depends on the quality of each journal. Country and language coverage depends on quality, even in the case of the best journals of each, although American biases may affect such selection. While a number of guidelines exist for identifying quality journals, information necessary to apply them confidently is often difficult to obtain. The National Library of Medicine is advised by an Ad Hoc Panel on the Selection of Journals for Index Medicus, composed both of NLM officers and extramural members. Criticism has been voiced that too many titles are indexed, compared with titles actually used, but no meaningful statistics of use exist which can identify titles which should be excluded from indexing. Continuing suggestions from users regarding titles indexed would benefit everyone. PMID:5922258

Truelson, Stanley D.

1966-01-01

352

CIRSE Vascular Closure Device Registry  

Microsoft Academic Search

Purpose  Vascular closure devices are routinely used after many vascular interventional radiology procedures. However, there have been\\u000a no major multicenter studies to assess the safety and effectiveness of the routine use of closure devices in interventional\\u000a radiology.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  The CIRSE registry of closure devices with an anchor and a plug started in January 2009 and ended in August 2009. A total\\u000a of

Jim A. ReekersStefan; Stefan Müller-Hülsbeck; Martin Libicher; Eli Atar; Jens Trentmann; Pierre Goffette; Jan Borggrefe; Kamil Zele?ák; Pieter Hooijboer; Anna-Maria Belli

2011-01-01

353

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.

354

Vascularization of carcinomas of the esophagus and its correlation with tumor proliferation.  

PubMed

Vascularization and tumor cell proliferation were analyzed in 33 resected human squamous cell carcinomas of the esophagus using the endothelium-specific antibody BW 200 and the proliferation-associated antibody Ki-67. Vascular parameters (relative capillary volume, relative total vessel volume, vascular surface area, and vascular length) as well as the percentage of proliferating tumor cells (Ki-67 index) were evaluated on frozen sections by a morphometric method. Vascular parameters of the normal mucosa exceeded those of tumors significantly, by a factor of 1.4-2.3. The mean distance between tumor capillaries and the onset of necrosis was 92 +/- 34 microns. Global vascular density did not correlate with TNM stage, tumor diameter, or overall tumor proliferation (mean Ki-67 index, 35.1%; range, 14.2-64.1%). However, a significant negative correlation existed between the percentage of proliferating tumor cells per tumor cord and the intercapillary distance between capillaries located at the edges of these cords. This observation points to the fact that the esophageal cancers were composed of multiple tumor cords and that each of these cords possessed its own supply capillaries at the base of the cord. The sum of these "supply units" thus constitutes an esophageal cancer. The intercapillary distance may reflect the oxygenation status of tumor cells, which cannot be predicted on the basis of tumor staging or grading. PMID:8275498

Porschen, R; Classen, S; Piontek, M; Borchard, F

1994-01-15

355

Review: Feto-placental vascularization: a multifaceted approach.  

PubMed

Doppler Ultrasound allows the in vivo study of feto-placental hemodynamics. Doppler flow velocity waveforms (FVW's) obtained from the umbilical arteries reflect downstream blood flow impedance, thus giving indirect evidence of vascular villous tree characteristics. Pulsatility Index, which quantifies FVW's, decreases throughout normal pregnancy, indicating decreasing impedance and is often higher in cases of fetal growth restriction (FGR). Different approaches (morphometrical, morphological, mathematical, immunohistochemical and molecular) have contributed to elucidation of which anomalies of the vascular villous tree underlie Doppler findings. 3D ultrasound may be useful in the study of feto-placental perfusion. However, the unsolved question is why developmental villous tree anomalies occur. Crucial to the success of future research is definition of the population studied based on the uniform and correct definition of FGR. PMID:21232791

Todros, T; Piccoli, E; Rolfo, A; Cardaropoli, S; Guiot, C; Gaglioti, P; Oberto, M; Vasario, E; Caniggia, I

2011-03-01

356

AGU index terms updated  

NASA Astrophysics Data System (ADS)

AGU has just completed a major revision of its Index Terms. The last major revision of the Index Terms was conducted in 1995. AGU Index Terms are used for classification of both AGU publications and meetings programs. The new Index Terms will be available for use by the AGU community on 17 December (http://www.agu.org/pubs/indexterms).A 15-person working group, representing various disciplinary groups across the AGU, was established by, and reports to, the Publications Committee. The Index Committee members consulted with their constituencies and considered term-by-term usage of the old Index Term list in creating the new list.

Kodama, Kenneth P.

2004-12-01

357

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...

358

Compaction and Transverse Permeability of Glass Rovings  

Microsoft Academic Search

Continuous reinforcements such as glass rovings are used in a variety of polymer processes such as filament winding and compression molding. In all these processes, impregnation of the roving fiber bundle by the liquid polymer is essential. Modeling polymer impregnation requires an estimate of the void fraction-compressive stress relationship and the transverse Darcy permeability. The void fraction of 2400 tex

P. J. Bates; D. Taylor; M. F. Cunningham

2001-01-01

359

EVALUATION OF PERMEABLE REACTIVE BARRIER PERFORMANCE  

EPA Science Inventory

The permeable reactive barrier (PRB) technology represents a passive option for long-term treatment of ground-water contamination. PRBs are a potentially more cost-effective treatment option for a variety of dissolved contaminants, such as certain types of chlorinated solvents, ...

360

Soak It Up: Understanding Amphibian Permeability  

NSDL National Science Digital Library

In this activity, learners will discover how the thin layers of amphibians' skin allow water and other chemicals to pass through it. Learners will also discover how different body coverings affect permeability. Learn why and how this affects their body, and what you can do to protect them in the wild. Thin skin is in, dirty environments are not!

Aquariums, Association O.

2009-01-01

361

Water permeability in human airway epithelium  

Microsoft Academic Search

Osmotic water permeability (Pf) was studied in spheroid-shaped human airway epithelia explants derived from nasal polyps by the use of a new improved tissue collection and isolation procedure. The fluid-filled spheroids were lined with a single cell layer with the ciliated apical cell membrane facing the outside. They were capable of surviving hours of experiment involving continuous superfusion of the

Peter Steen Pedersen; Kristina Procida; Per Leganger Larsen; Niels-Henrik Holstein-Rathlou; Ole Frederiksen

2005-01-01

362

Permeability of muscle capillaries to microperoxidase  

PubMed Central

In this study we attempted to identify a morphologic counterpart of the small pore of muscle capillaries. The existence of such a pore has been postulated by physiologists to explain the permeability of muscle capillaries to small macromolecules. We injected mice intravenously with microperoxidase (MP) and fixed specimens of diaphragm at intervals of 0-250 s after the injection to localize the tracer by electron microscopy. The small size of MP (1,900 mol wt and 20 A molecular diameter [MD]) ensures its ready passage through the small pore since the latter is thought to be either a cylindrical channel 90 A in diameter or a slit 55 A wide. MP appears in the pericapillary interstitium within 30 s of initiation of its intravenous injection. The patterns of localization of MP observed within clefts between adjacent capillary endothelial cells indicate that some endothelial junctions are permeable to this tracer. Although small vesicles transfer MP across the endothelium, we do not believe that the vesicles transfer substantial amounts of MP into the pericapillary interstitium. We did not obtain evidence that MP crosses the endothelium of capillaries through channels formed either by a single vesicle or by a series of linked vesicles opening simultaneously at both surfaces of the endothelial cell. From our observations we conclude that some endothelial junctions of capillaries are permeable to MP, and that these permeable junctions are a plausible morphologic counterpart of the small pore. PMID:10605442

Wissig, S. L.; Williams, M. C.

1978-01-01

363

Broadband reflectance spectroscopy for establishing a quantitative metric of vascular leak using the Miles assay  

NASA Astrophysics Data System (ADS)

Monitoring the physiological effects of biological mediators on vascular permeability is important for identifying potential targets for antivascular leak therapy. This therapy is relevant to treatments for pulmonary edema and other disorders. Current methods of quantifying vascular leak are in vitro and do not allow repeated measurement of the same animal. Using an in vivo diffuse reflectance optical method allows pharmacokinetic analysis of candidate antileak molecules. Here, vascular leak is assessed in mice and rats by using the Miles assay and introducing irritation both topically using mustard oil and intradermally using vascular endothelial growth factor (VEGF). The severity of the leak is assessed using broadband diffuse reflectance spectroscopy with a fiber reflectance probe. Postprocessing techniques are applied to extract an artificial quantitative metric of leak from reflectance spectra at vascular leak sites on the skin of the animal. This leak metric is calculated with respect to elapsed time from irritation in both mustard oil and VEGF treatments on mice and VEGF treatments on rats, showing a repeatable increase in leak metric with leak severity. Furthermore, effects of pressure on the leak metric are observed to have minimal effect on the reflectance spectra, while spatial positioning showed spatially nonuniform leak sites.

McMurdy, John; Reichner, Jonathan; Mathews, Zara; Markey, Mary; Intwala, Sunny; Crawford, Gregory

2009-09-01

364

Tetraspanin CD151 maintains vascular stability by balancing the forces of cell adhesion and cytoskeletal tension  

PubMed Central

Tetraspanin CD151 is highly expressed in endothelial cells and regulates pathologic angiogenesis. However, the mechanism by which CD151 promotes vascular morphogenesis and whether CD151 engages other vascular functions are unclear. Here we report that CD151 is required for maintaining endothelial capillary-like structures formed in vitro and the integrity of endothelial cell-cell and cell-matrix contacts in vivo. In addition, vascular permeability is markedly enhanced in the absence of CD151. As a global regulator of endothelial cell-cell and cell-matrix adhesions, CD151 is needed for the optimal functions of various cell adhesion proteins. The loss of CD151 elevates actin cytoskeletal traction by up-regulating RhoA signaling and diminishes actin cortical meshwork by down-regulating Rac1 activity. The inhibition of RhoA or activation of cAMP signaling stabilizes CD151-silenced or -null endothelial structure in vascular morphogenesis. Together, our data demonstrate that CD151 maintains vascular stability by promoting endothelial cell adhesions, especially cell-cell adhesion, and confining cytoskeletal tension. PMID:21832275

Zhang, Feng; Michaelson, Jarett E.; Moshiach, Simon; Sachs, Norman; Zhao, Wenyuan; Sun, Yao; Sonnenberg, Arnoud; Lahti, Jill M.; Huang, Hayden

2011-01-01

365

The Endothelial Transcription Factor ERG Promotes Vascular Stability and Growth through Wnt/?-Catenin Signaling  

PubMed Central

Summary Blood vessel stability is essential for embryonic development; in the adult, many diseases are associated with loss of vascular integrity. The ETS transcription factor ERG drives expression of VE-cadherin and controls junctional integrity. We show that constitutive endothelial deletion of ERG (ErgcEC-KO) in mice causes embryonic lethality with vascular defects. Inducible endothelial deletion of ERG (ErgiEC-KO) results in defective physiological and pathological angiogenesis in the postnatal retina and tumors, with decreased vascular stability. ERG controls the Wnt/?-catenin pathway by promoting ?-catenin stability, through signals mediated by VE-cadherin and the Wnt receptor Frizzled-4. Wnt signaling is decreased in ERG-deficient endothelial cells; activation of Wnt signaling with lithium chloride, which stabilizes ?-catenin levels, corrects vascular defects in ErgcEC-KO embryos. Finally, overexpression of ERG in vivo reduces permeability and increases stability of VEGF-induced blood vessels. These data demonstrate that ERG is an essential regulator of angiogenesis and vascular stability through Wnt signaling. PMID:25584796

Birdsey, Graeme M.; Shah, Aarti V.; Dufton, Neil; Reynolds, Louise E.; Osuna Almagro, Lourdes; Yang, Youwen; Aspalter, Irene M.; Khan, Samia T.; Mason, Justin C.; Dejana, Elisabetta; Göttgens, Berthold; Hodivala-Dilke, Kairbaan; Gerhardt, Holger; Adams, Ralf H.; Randi, Anna M.

2015-01-01

366

ROBO4-Mediated Vascular Integrity Regulates the Directionality of Hematopoietic Stem Cell Trafficking  

PubMed Central

Summary Despite the use of hematopoietic stem cells (HSCs) in clinical therapy for over half a century, the mechanisms that regulate HSC trafficking, engraftment, and life-long persistence after transplantation are unclear. Here, we show that the vascular endothelium regulates HSC trafficking into and out of bone marrow (BM) niches. Surprisingly, we found that instead of acting as barriers to cellular entry, vascular endothelial cells, via the guidance molecule ROBO4, actively promote HSC translocation across vessel walls into the BM space. In contrast, we found that the vasculature inhibits the reverse process, as induced vascular permeability led to a rapid increase in HSCs in the blood stream. Thus, the vascular endothelium reinforces HSC localization to BM niches both by promoting HSC extravasation from blood-to-BM and by forming vascular barriers that prevent BM-to-blood escape. Our results uncouple the mechanisms that regulate the directionality of HSC trafficking and show that the vasculature can be targeted to improve hematopoietic transplantation therapies. PMID:25640759

Smith-Berdan, Stephanie; Nguyen, Andrew; Hong, Matthew A.; Forsberg, E. Camilla

2015-01-01

367

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

368

The Endothelial Transcription Factor ERG Promotes Vascular Stability and Growth through Wnt/?-Catenin Signaling.  

PubMed

Blood vessel stability is essential for embryonic development; in the adult, many diseases are associated with loss of vascular integrity. The ETS transcription factor ERG drives expression of VE-cadherin and controls junctional integrity. We show that constitutive endothelial deletion of ERG (Erg(cEC-KO)) in mice causes embryonic lethality with vascular defects. Inducible endothelial deletion of ERG (Erg(iEC-KO)) results in defective physiological and pathological angiogenesis in the postnatal retina and tumors, with decreased vascular stability. ERG controls the Wnt/?-catenin pathway by promoting ?-catenin stability, through signals mediated by VE-cadherin and the Wnt receptor Frizzled-4. Wnt signaling is decreased in ERG-deficient endothelial cells; activation of Wnt signaling with lithium chloride, which stabilizes ?-catenin levels, corrects vascular defects in Erg(cEC-KO) embryos. Finally, overexpression of ERG in vivo reduces permeability and increases stability of VEGF-induced blood vessels. These data demonstrate that ERG is an essential regulator of angiogenesis and vascular stability through Wnt signaling. PMID:25584796

Birdsey, Graeme M; Shah, Aarti V; Dufton, Neil; Reynolds, Louise E; Osuna Almagro, Lourdes; Yang, Youwen; Aspalter, Irene M; Khan, Samia T; Mason, Justin C; Dejana, Elisabetta; Göttgens, Berthold; Hodivala-Dilke, Kairbaan; Gerhardt, Holger; Adams, Ralf H; Randi, Anna M

2015-01-12

369

Vascular origin of Poland syndrome?  

Microsoft Academic Search

Vascularization of the arms has been studied by impedance plethysmography (rheography) in eight children with Poland syndrome, a common malformation characterized by unilateral hand anomaly and ipsilateral aplasia of the inferior head of the pectoralis major muscle. A marked decrease of the velocity of the systolic increase in the arterial volume (Velm) was shown in the affected arms, and the

Jean-Pierre Bouvet; Denis Leveque; Francine Bernetieres; Jean-Jacques Gros

1978-01-01

370

Vascular basis of mucosal color  

PubMed Central

Background Besides the color of the teeth the color of the alveolar gingiva plays a crucial role in esthetic rehabilitation in dento-alveolar treatment. Whereas nowadays the color of the teeth can be determined exactly and individually, the specific influence of the red color of the gingiva on treatment has not been assessed yet. The aim of this study was to evaluate the vascularization as the basis for gingival esthetics. Methods Standardized photographs of defined areas of the alveolar gingiva in operated and non-operated patients were taken and assigned to groups with same characteristics after color comparisons. In addition, histologic and immunohistologic analyses of gingival specimens were performed for qualitative and quantitative assessment of vessels and vascularization. Finally, colors and number of vessels were correlated. Results Our results demonstrated three different constellations of colors of the alveolar gingiva in healthy patients. The operated patients could not be grouped because of disparate depiction. There was a clear correlation between color and vessel number in the alveolar gingiva. Conclusion Our investigations revealed the connections between vascularization and gingival color. Recommendations for specific change or even selection of colors based on the results cannot be given, but the importance of vascularly based incision lines was demonstrated. PMID:16270929

Kleinheinz, Johannes; Büchter, André; Fillies, Thomas; Joos, Ulrich

2005-01-01

371

Advances in vascular echoplanar imaging  

Microsoft Academic Search

Magnetic resonance (MR) angiography is emerging as an increasingly useful tool for the noninvasive evaluation of the cardiovascular system. Ultrafast echoplanar imaging (EPI) data acquisition strategies are becoming more widely available. When applied to MR angiography, the associated reduction in data collection time allows breathheld acquisitions of entire vascular territories, as well as the exploitation of short-lived flow-enhancing measures. This

Jiirg F. Debatin; Daniel A. Leung; Simon Wildermuth; Daniel Holtz; Graeme C. McKinnon

1995-01-01

372

Permeability properties of peroxisomal membranes from yeasts.  

PubMed

We have studied the permeability properties of intact peroxisomes and purified peroxisomal membranes from two methylotrophic yeasts. After incorporation of sucrose and dextran in proteoliposomes composed of asolectin and peroxisomal membranes isolated from the yeasts Hansenula polymorpha and Candida boidinii a selective leakage of sucrose occurred indicating that the peroxisomal membranes were permeable to small molecules. Since the permeability of yeast peroxisomal membranes in vitro may be due to the isolation procedure employed, the osmotic stability of peroxisomes was tested during incubations of intact protoplasts in hypotonic media. Mild osmotic swelling of the protoplasts also resulted in swelling of the peroxisomes present in these cells but not in a release of their matrix proteins. The latter was only observed when the integrity of the cells was disturbed due to disruption of the cell membrane during further lowering of the concentration of the osmotic stabilizer. Stability tests with purified peroxisomes indicated that this leak of matrix proteins was not associated with the permeability to sucrose. Various attempts to mimic the in vivo situation and generate a proton motive force across the peroxisomal membranes in order to influence the permeability properties failed. Two different proton pumps were used for this purpose namely bacteriorhodopsin (BR) and reaction center-light-harvesting complex I (RCLH1 complex). After introduction of BR into the membrane of intact peroxisomes generation of a pH-gradient was not or barely detectable. Since this pump readily generated a pH-gradient in pure liposomes, these results strengthened the initial observations on the leakiness of the peroxisomal membrane fragments.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2339956

Douma, A C; Veenhuis, M; Sulter, G J; Waterham, H R; Verheyden, K; Mannaerts, G P; Harder, W

1990-01-01

373

The effects of the ovarian cycle and pregnancy on uterine vascular impedance and uterine artery mechanics  

E-print Network

The effects of the ovarian cycle and pregnancy on uterine vascular impedance and uterine artery and large arteries, to determine the effects of the ovarian cycle and pregnancy on the entire uterine into arterial size and stiffness, and index of wave reflection (RW), which reflects the effects of taper

Chesler, Naomi C.

374

Improving the passive permeability of macrocyclic peptides: Balancing permeability with other physicochemical properties.  

PubMed

A number of methods to improve the passive permeability of a set of cyclic peptides have been investigated using 6- and 7-mer macrocyclic templates. In many cases the peptides were designed by molecular dynamics calculations to evaluate the methods. The aim of this study was not only to improve passive permeability, but also to balance permeability with other physicochemical properties with the goal of understanding and applying the knowledge to develop active cyclic peptides into drug candidates. Evaluation of the methods herein suggest that increasing passive permeability often occurs at the expense of solubility and lipophilicity. Computational methods can be useful when attempting to predict and design features to balance these properties, though limitations were observed. PMID:25533323

Thansandote, Praew; Harris, Robert M; Dexter, Hannah L; Simpson, Graham L; Pal, Sandeep; Upton, Richard J; Valko, Klara

2015-01-15

375

The primary vascular dysregulation syndrome: implications for eye diseases  

PubMed Central

Vascular dysregulation refers to the regulation of blood flow that is not adapted to the needs of the respective tissue. We distinguish primary vascular dysregulation (PVD, formerly called vasospastic syndrome) and secondary vascular dysregulation (SVD). Subjects with PVD tend to have cold extremities, low blood pressure, reduced feeling of thirst, altered drug sensitivity, increased pain sensitivity, prolonged sleep onset time, altered gene expression in the lymphocytes, signs of oxidative stress, slightly increased endothelin-1 plasma level, low body mass index and often diffuse and fluctuating visual field defects. Coldness, emotional or mechanical stress and starving can provoke symptoms. Virtually all organs, particularly the eye, can be involved. In subjects with PVD, retinal vessels are stiffer and more irregular, and both neurovascular coupling and autoregulation capacity are reduced while retinal venous pressure is often increased. Subjects with PVD have increased risk for normal-tension glaucoma, optic nerve compartment syndrome, central serous choroidopathy, Susac syndrome, retinal artery and vein occlusions and anterior ischaemic neuropathy without atherosclerosis. Further characteristics are their weaker blood–brain and blood-retinal barriers and the higher prevalence of optic disc haemorrhages and activated astrocytes. Subjects with PVD tend to suffer more often from tinnitus, muscle cramps, migraine with aura and silent myocardial ischaemic and are at greater risk for altitude sickness. While the main cause of vascular dysregulation is vascular endotheliopathy, dysfunction of the autonomic nervous system is also involved. In contrast, SVD occurs in the context of other diseases such as multiple sclerosis, retrobulbar neuritis, rheumatoid arthritis, fibromyalgia and giant cell arteritis. Taking into consideration the high prevalence of PVD in the population and potentially linked pathologies, in the current article, the authors provide recommendations on how to effectively promote the field in order to create innovative diagnostic tools to predict the pathology and develop more efficient treatment approaches tailored to the person. PMID:23742177

2013-01-01

376

The primary vascular dysregulation syndrome: implications for eye diseases.  

PubMed

Vascular dysregulation refers to the regulation of blood flow that is not adapted to the needs of the respective tissue. We distinguish primary vascular dysregulation (PVD, formerly called vasospastic syndrome) and secondary vascular dysregulation (SVD). Subjects with PVD tend to have cold extremities, low blood pressure, reduced feeling of thirst, altered drug sensitivity, increased pain sensitivity, prolonged sleep onset time, altered gene expression in the lymphocytes, signs of oxidative stress, slightly increased endothelin-1 plasma level, low body mass index and often diffuse and fluctuating visual field defects. Coldness, emotional or mechanical stress and starving can provoke symptoms. Virtually all organs, particularly the eye, can be involved. In subjects with PVD, retinal vessels are stiffer and more irregular, and both neurovascular coupling and autoregulation capacity are reduced while retinal venous pressure is often increased. Subjects with PVD have increased risk for normal-tension glaucoma, optic nerve compartment syndrome, central serous choroidopathy, Susac syndrome, retinal artery and vein occlusions and anterior ischaemic neuropathy without atherosclerosis. Further characteristics are their weaker blood-brain and blood-retinal barriers and the higher prevalence of optic disc haemorrhages and activated astrocytes. Subjects with PVD tend to suffer more often from tinnitus, muscle cramps, migraine with aura and silent myocardial ischaemic and are at greater risk for altitude sickness. While the main cause of vascular dysregulation is vascular endotheliopathy, dysfunction of the autonomic nervous system is also involved. In contrast, SVD occurs in the context of other diseases such as multiple sclerosis, retrobulbar neuritis, rheumatoid arthritis, fibromyalgia and giant cell arteritis. Taking into consideration the high prevalence of PVD in the population and potentially linked pathologies, in the current article, the authors provide recommendations on how to effectively promote the field in order to create innovative diagnostic tools to predict the pathology and develop more efficient treatment approaches tailored to the person. PMID:23742177

Flammer, Josef; Konieczka, Katarzyna; Flammer, Andreas J

2013-01-01

377

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

378

PERMEABILITY OF SOILS TO FOUR ORGANIC LIQUIDS AND WATER  

EPA Science Inventory

Saturated hydraulic conductivities and intrinsic permeabilities were evaluated for eight contrasting soils with four organic liquids and water. The organic liquids were kerosene, ethylene glycol, isopropyl alcohol and xylene. Intrinsic permeability for any given soil varied inver...

379

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

380

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

E-print Network

enough; however, the Swagelock can be easily damaged if over tightened. 36 (3) Dry the cores in the humidity oven with s, temperature of 60' F and a relative humidity of 45% until the weight of each sample stabilizes. (4) Measure the absolute...THE MEASUREMENT OF GAS RELATIVE PERMEABILITY FOR LOW PERMEABILITY CORES USING A PRESSURE TRANSIENT METHOD A Thesis by XIUXU NING Submitted to the Office of Graduate Studies of Texas Ag M University in partial fulfillment of the requirements...

Ning, Xiuxu

1989-01-01

381

The Database Index.  

ERIC Educational Resources Information Center

Describes the characteristics of System Development Corporation's (SDC) online index to its database, "Database Index," and presents the results of various test searches to demonstrate the limitations and benefits of the new online file. (JD)

Antony, Arthur

1979-01-01

382

[Overview of the vascular interventional surgery robot].  

PubMed

In vascular invasive surgery procedures, because doctors suffered from a large number of X-ray radiation, and it is difficult to manipulate catheter, so vascular interventional robot has been rapidly developed. On the basis of analysis of vascular surgical intervention process, key technologies of vascular interventional surgical robots are provided. The image navigation system, the mechanical structure, control systems and force feedback are also analyzed. PMID:23777068

Li, Shenglin; Shen, Jie; Yan, Yonghua; Chen, Daguo

2013-03-01

383

Neurofibromas with imaging characteristics resembling vascular anomalies.  

PubMed

OBJECTIVE. Although neurofibromas are rare, their initial clinical and imaging presentation can mimic those of vascular anomalies, particularly if the characteristic clinical features of neurofibromatosis are not present. The diagnostic challenges encountered in five cases of histologically proven neurofibromas, initially diagnosed as vascular anomalies, are reviewed and discussed. CONCLUSION. The clinical and imaging differences between neurofibromas and vascular anomalies are detailed with the histopathologic features to better understand why some neurofibromas are diagnosed as vascular anomalies. PMID:25415736

Yilmaz, Sabri; Ozolek, John A; Zammerilla, Lauren L; Fitz, Charles R; Grunwaldt, Lorelei J; Crowley, John J

2014-12-01

384

Low-level X-radiation effects on functional vascular changes in Syrian hamster cheek pouch epithelium during hydrocarbon carcinogenesis  

Microsoft Academic Search

Effects of repeated low-level X radiation on functional microvascular changes in hamster cheek pouch epithelium during and following carcinogenesis by 7,12-dimethylbenz(a)anthracene (DMBA) were studied. Hamsters were treated with either radiation, DMBA, radiation + DMBA, or no treatment. Animals were sacrificed at 3-week intervals from 0 to 39 weeks after treatments began. Pouch vascular volume and permeability changes were studied by

A. G. Lurie; J. E. Coghill; R. M. Rippey

1985-01-01

385

Roles of transglutaminases in cardiac and vascular diseases  

PubMed Central

All transglutaminases share the common enzymatic activity of transamidation, or the cross-linking of glutamine and lysine residues to form N epsilon (gamma-glutamyl) lysyl isopeptide bonds. The plasma proenzyme factor XIII is responsible for stabilizing the fibrin clot against physical and fibrinolytic disruption. Another member of the transglutaminase family, tissue transglutaminase or TG2 is abundantly expressed in cardiomyocytes, vascular cells and macrophages. The transglutaminases have a variety of functions independent of their transamidating activity. For example, TG2 binds and hydrolyzes GTP, thereby fostering signal transduction by several G protein coupled receptors. Accumulating evidence points to novel roles for factor XIII and TG2 in cardiovascular biology including: (a) modulating platelet activity, (b) regulating glucose control, (c) contributing to the development of hypertension, (d) influencing the progression of atherosclerosis, (e) regulating vascular permeability and angiogenesis (f) and contributing to myocardial signaling, contractile activity and ischemia/reperfusion injury. In this review, we summarize the cardiovascular biology of two members of the family of transglutaminases, Factor XIII and TG2. PMID:17127261

Sane, David C.; Kontos, Jimmy L.; Greenberg, Charles S.

2007-01-01

386

Interaction of vortex rings with multiple permeable screens  

NASA Astrophysics Data System (ADS)

Interaction of a vortex ring impinging on multiple permeable screens orthogonal to the ring axis was studied to experimentally investigate the persistence and decay of vortical structures inside the screen array using digital particle image velocimetry in a refractive index matched environment. The permeable screens had porosities (open area ratios) of 83.8%, 69.0%, and 55.7% and were held by a transparent frame that allowed the screen spacing to be changed. Vortex rings were generated using a piston-cylinder mechanism at nominal jet Reynolds numbers of 1000, 2000, and 3000 with piston stroke length-to-diameter ratios of 2 and 3. The interaction of vortex rings with the porous medium showed a strong dependence of the overall flow evolution on the screen porosity, with a central flow being preserved and vortex ring-like structures (with smaller diameter than the primary vortex ring) being generated near the centerline. Due to the large rod size used in the screens, immediate reformation of the transmitted vortex ring with size comparable to the primary ring (as has been observed with thin screens) was not observed in most cases. Since the screens have lower complexity and high open area ratios, centerline vortex ring-like flow structures formed with comparable size to the screen pore size and penetrated through the screens. In the case of low porosity screens (55.7%) with large screen spacing, re-emergence of large scale (large separation), weak vortical structures/pairs (analogous to a transmitted vortex ring) was observed downstream of the first screen. Additional smaller scale vortical structures were generated by the interaction of the vortex ring with subsequent screens. The size distribution of the generated vortical structures were shown to be strongly affected by porosity, with smaller vortical structures playing a stronger role as porosity decreased. Finally, porosity significantly affected the decay of total energy, but the effect of screen spacing decreased as porosity decreased.

Musta, Mustafa N.; Krueger, Paul S.

2014-11-01

387

Vascular deposition patterns for nanoparticles in an inflamed patient-specific arterial tree.  

PubMed

Inflammation, a precursor to many diseases including cancer and atherosclerosis, induces differential surface expression of specific vascular molecules. Blood-borne nanoparticles (NPs), loaded with therapeutic and imaging agents, can recognize and use these molecules as vascular docking sites. Here, a computational model is developed within the isogeometric analysis framework to understand and predict the vascular deposition of NPs within an inflamed arterial tree. The NPs have a diameter ranging from 0.1 to 2.0 ?m and are decorated with antibodies directed toward three endothelial adhesion molecules, namely intravascular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin, whose surface density depends on the local wall shear stress. Results indicate VCAM-1 targeted NPs adhere more, with ICAM-1 directed NPs adhering least efficiently, resulting in approximately an order-of-magnitude lower average particle surface density. ICAM-1 and E-selectin directed 0.5 ?m NPs are distributed more uniformly (heterogeneity index ? 0.9 and 1.0, respectively) over the bifurcating vascular branches compared to their VCAM-1 counterparts (heterogeneity index ? 1.4). When the NPs are coated with antibodies for VCAM-1 and E-selectin in equal proportions, a more uniform vascular distribution is achieved compared with VCAM-1-only targeted particles, thus demonstrating the advantage of NP multivalency in vascular targeting. Furthermore, the larger NPs (2 ?m) adhere more (? 200%) in the lower branches compared to the upper branch. This computational framework provides insights into how size, ligand type, density, and multivalency can be manipulated to enhance NP vascular adhesion in an individual patient. PMID:23942910

Hossain, Shaolie S; Hughes, Thomas J R; Decuzzi, Paolo

2014-06-01

388

Amplatzer Vascular Plug: Expanding the Applications Spectrum  

SciTech Connect

The Amplatzer Vascular Plug is a new embolization device which has been used in different vascular anomalies, especially by cardiologists in the cardiac and pulmonary circulations. It is underused by interventional radiologists. We used this device in three different vascular conditions, which we present here.

Rimon, Uri, E-mail: rimonu@sheba.health.gov.i [Sheba Medical Center (affiliated to the 'Sackler' School of Medicine, Tel-Aviv University, Tel-Aviv, Israel), Department of Diagnostic Imaging (Israel); Heldenberg, Eitan [Sheba Medical Center (affiliated to the 'Sackler' School of Medicine, Tel-Aviv University, Tel-Aviv, Israel), Department of Vascular Surgery (Israel); Golan, Gil [Sheba Medical Center (affiliated to the 'Sackler' School of Medicine, Tel-Aviv University, Tel-Aviv, Israel), Department of Diagnostic Imaging (Israel); Shinfeld, Amichai [Sheba Medical Center (affiliated to the 'Sackler' School of Medicine, Tel-Aviv University, Tel-Aviv, Israel), Department of Cardiac Surgery (Israel); Garniek, Alexander [Sheba Medical Center (affiliated to the 'Sackler' School of Medicine, Tel-Aviv University, Tel-Aviv, Israel), Department of Diagnostic Imaging (Israel)

2008-07-15

389

Vascular Patterning: More Than Just Didier Reinhardt  

E-print Network

Vascular Patterning: More Than Just Auxin? Didier Reinhardt The plant hormone auxin has long been of them involving sterols. Plants exhibit characteristic vascular patterns in the stem and in leaves [1 of auxin function? During plant development, auxin induces the formation of vascular strands [3,4], along

Kuhlemeier, Cris

390

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.

391

California Nitrogen Index  

Technology Transfer Automated Retrieval System (TEKTRAN)

The California N Index User Manual is designed to help you become accustomed to the software environment in which the N Index runs. This manual will use an example scenario to demonstrate how to use the N Index to assess nitrogen losses. The objective of this theoretical example is to guide you towa...

392

The Europe 2020 Index  

ERIC Educational Resources Information Center

This paper presents a new index to quantify, measure and monitor the progress towards the objectives of the Europe 2020 strategy. This index is based on a set of relevant, accepted, credible, easy to monitor and robust indicators presented by the European Commission at the time the strategy was launched. The internal analysis of the index shows…

Pasimeni, Paolo

2013-01-01

393

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

PubMed Central

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) 320D) suggested 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 18F-FLT (MW 244D) accumulated in the brain at week 4. Gadolinium-based MRI tracers (MW 559D and 2.066kD) 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 64Cu-BSA (MW 65.55kD) 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 18F-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.

2013-01-01

394

Studying the Variation in Gas Permeability of Porous Building Substrates  

NASA Astrophysics Data System (ADS)

Understanding permeability of building materials is important for problems involving studies of contaminant transport. Examples include contamination from fire, acid rain, and chemical and biological weapons. Our research investigates the gas permeability of porous building substrates such as concretes, limestones, sandstones, and bricks. Each sample was cored to produce 70 mm (2.75”) diameter cores approximately 75-130 mm (3-5”) tall. The surface gas permeability was measured on the top surface of these specimens using the AutoScan II device manufactured by New England Research, Inc. The measurements were taken along a 3 mm grid producing a map of surface gas permeability. An example map is shown in Figure 1. The macroscopic measurements were performed along the entire cored specimen. A second set of measurements were made on a 5 mm thick slice cut from the top of each specimen to examine whether these measurements compare better with the surface measurements. The macroscopic gas permeability was measured for all specimens using ASTM D 4525. The results are summarized in Table 1. In general, the surface and macroscopic gas permeability measurements (Table 1) compare reasonably well (within one order of magnitude). The permeability of the 5 mm slices is not significantly different from the entire core for the specimens tested. Figure 1. Results of surface permeability mappingof Ohio Sandstone using the AutoScan II device. a) Map of gas permeability b) Range of gas permeability c) Density function of permeability. Table 1. Gas permeability values (mD)

Townsend, L.; Savidge, C. R.; Hu, L.; Rizzo, D. M.; Hayden, N. J.; Dewoolkar, M.

2009-12-01

395

EOSC 252 Assignment 1. Porosity, permeability and Darcy's law Introduction  

E-print Network

EOSC 252 Assignment 1. Porosity, permeability and Darcy's law Introduction Fluid flow within porous are examples. The way in which fluids move in these settings depends on the porosity and permeability of the solid medium. To build understanding of the relationship between porosity and permeability it is useful

Jellinek, Mark

396

Original article Permeability of milk protein antigens across the intestinal  

E-print Network

Original article Permeability of milk protein antigens across the intestinal epithelium in vitro D by proteolytic enzymes and intestinal epithelial permeability represent two major drawbacks to the transfer-cas. These results suggest a selective intestinal permeability for milk protein antigens. This selectivity

Paris-Sud XI, Université de

397

Negative Refractive Index in Left-Handed Materials  

Microsoft Academic Search

The real part of the refractive index n\\\\(omega\\\\) of a nearly transparent and passive medium is usually taken to have only positive values. Through an analysis of a current source radiating into a 1D ``left-handed'' material (LHM)-where the permittivity and permeability are simultaneously less than zero-we determine the analytic structure of n\\\\(omega\\\\), demonstrating frequency regions where the sign of Re[n\\\\(omega\\\\)

David R. Smith; Norman Kroll

2000-01-01

398

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

399

Permeability Changes in Reaction Induced Fracturing  

NASA Astrophysics Data System (ADS)

The process of fracture formation due to a volume increasing chemical reaction has been studied in a variety of different settings, e.g. weathering of dolerites by Røyne et al.[4], serpentinization and carbonation of peridotite by Rudge et al.[3] and replacement reactions in silica-poor igneous rocks by Jamtveit et al.[1]. It is generally assumed that fracture formation will increase the net permeability of the rock, and thus increase the reactant transport rate and subsequently the total reaction rate, as summarised by Kelemen et al.[2]. Røyne et al.[4] have shown that transport in fractures will have an effect on the fracture pattern formed. Understanding the feedback process between fracture formation and permeability changes is essential in assessing industrial scale CO2 sequestration in ultramafic rock, but little is seemingly known about how large the permeability change will be in reaction-induced fracturing under compression, and it remains an open question how sensitive a fracture pattern is to permeability changes. In this work, we study the permeability of fractures formed under compression, and we use a 2D discrete element model to study the fracture patterns and total reaction rates achieved with different permeabilities. We achieve an improved understanding of the feedback processes in reaction-driven fracturing, thus improving our ability to decide whether industrial scale CO2 sequestration in ultramafic rock is a viable option for long-term handling of CO2. References [1] Jamtveit, B, Putnis, C. V., and Malthe-Sørenssen, A., "Reaction induced fracturing during replacement processes," Contrib. Mineral Petrol. 157, 2009, pp. 127 - 133. [2] Kelemen, P., Matter, J., Streit, E. E., Rudge, J. F., Curry, W. B., and Blusztajn, J., "Rates and Mechanisms of Mineral Carbonation in Peridotite: Natural Processes and Recipes for Enhanced, in situ CO2 Capture and Storage," Annu. Rev. Earth Planet. Sci. 2011. 39:545-76. [3] Rudge, J. F., Kelemen, P. B., and Spiegelman, M., "A simple model of reaction induced cracking applied to serpentinization and carbonation of peridotite," Earth Planet. Sci. Lett. 291, Issues 1-4, 2010, pp. 215 - 227. [4] Røyne, A., Jamtveit, B., and Malthe-Sørenssen, A., "Controls on rock weathering rates by reaction-induced hierarchial fracturing," Earth Planet. Sci. Lett. 275, 2008, pp. 364 - 369.

Ulven, Ole Ivar; Malthe-Sørenssen, Anders; Kalia, Rajiv

2013-04-01

400

Determination of formation permeability using back-pressure test data from hydraulically-fractured, low-permeability gas wells  

E-print Network

DETERMINATION OF FORMATION PERMEABILITY USING BACX-PRESSURE TEST DATA FROM HYDRAULICALLY-FRACTURED, LOW-PERMEABILITY GAS WELLS A Thesis JOHN PAUL KRAWTZ Submitted to the Graduate College of Texas AsJ4 University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 1984 Major subject: petroleum Engineering DETERMINATION OF FORMATION PERMEABILITY USING BACK-PRESSURE TEST DATA FROM HYDRAULICALLY-FRACTURED, LOW-PERMEABILITY GAS WELLS A Thesis JOHN PAUL KRAWTZ...

Krawtz, John Paul

1984-01-01

401

On noninferior performance index vectors  

Microsoft Academic Search

The noninferior vector index problem of optimal control theory is investigated in an effort to establish some basic properties of the noninferior index surface in the generalN-dimensional index problem. The vector performance index problem is first converted to a family of scalar index problems by forming an auxiliary scalar index as a function of the vector index and a vector

R. W. Reid; S. J. Citron

1971-01-01

402

Hydrogeologic modeling for permeable reactive barriers.  

PubMed

The permeable reactive barrier technology for in situ treatment of chlorinated solvents and other groundwater contaminants is becoming increasingly popular. Field scale implementation of this and other in situ technologies requires careful design based on the site-specific hydrogeology and contaminant plume characteristics. Groundwater flow modeling is an important tool in understanding the hydraulic behavior of the site and optimizing the reactive barrier design. A combination of groundwater flow modeling and particle tracking techniques was used to illustrate the effect of hydraulic conductivity of the aquifer and reactive media on key permeable barrier design parameters, such as the capture zone width, residence time, flow velocity, and discharge. Similar techniques were used to illustrate the modeling approach for design of different configurations of reactive barriers in homogeneous and heterogeneous settings. PMID:10518663

Gupta, N; Fox, T C

1999-08-12

403

Pulmonary epithelial permeability is immediately increased after embolisation with oleic acid but not with neutral fat.  

PubMed Central

Pulmonary fat embolism occurs frequently after trauma but its functional significance is often unclear. To obtain direct evidence of lung damage caused by fat embolism we have measured changes in permeability of the alveolar-capillary interface. A permeability index was derived from the half time clearance from lung to blood (T1/2LB) of 99mTcDTPA introduced into the lung in a 1 ml bolus. Three groups of rabbits were studied. Baseline T1/2LB. did not differ significantly between groups. After intravenous injection of saline placebo in one group and of 300 mg/kg triolein in another group there was no change in permeability index. After intravenous injection of 100 mg/kg oleic acid in the third group there was an immediate change in T1/2LB from a monoexponential baseline 280 +/- 20 min (SEM) to a multiexponential curve which was resolved into two components, one with a T1/2LB of 3.2 +/- 0.6 min (SEM) and the other 39.5 +/- 7.6 min (SEM). Statistically significant changes in alveolar-arterial PO2 difference, dynamic compliance, chest radiography, and postmortem lung water accompanied the changes in T1/2LB in this group. There were no significant changes in these variables in the placebo or triolein group. Histological studies of the lung tissue of these animals using the osmic acid stain for fat showed no fat in the placebo group, extensive fat embolisation which was densely stained in the triolein group and much less densely stained fat in the oleic acid group. Measurement of the permeability of the alveolar-capillary interface provides direct evidence of lung damage after oleic acid embolisation. There were no functional changes in animals with extensive embolisation with triolein. Images PMID:7101221

Jones, J G; Minty, B D; Beeley, J M; Royston, D; Crow, J; Grossman, R F

1982-01-01

404

The European experience with vascular injuries.  

PubMed

The rich and diverse heritage of the management of vascular injuries in the 45 independent European countries prevents the authors from revealing a uniform picture of the European experience, but some trends are clearly emerging. In countries with a low incidence of penetrating trauma and increasing use of interventional vascular procedures, the proportion of iatrogenic vascular trauma exceeds 40% of all vascular injuries, whereas on other parts of the continent, armed conflicts are still a major cause of vascular trauma. National vascular registries, mostly in the Scandinavian countries, produce useful, nationwide data about vascular trauma and its management but suffer still from inadequate data collection. Despite a relatively low incidence of vascular trauma in most European countries, the results are satisfactory, probably in most cases because of active and early management by surgeons on call, whether with vascular training or not, treating all kinds of vascular surgical emergencies. In some countries, attempts at developing a trauma and emergency surgical specialty, including expertise in the management of vascular injuries, are on their way. PMID:11905944

Fingerhut, Abe; Leppäniemi, Ari K; Androulakis, George A; Archodovassilis, F; Bouillon, Bertil; Cavina, Enrico; Chaloner, Eddie; Chiarugi, Massimo; Davidovic, Lazar; Delgado-Millan, Miguel Angel; Goris, Jan; Gunnlaugsson, Gunnar H; Jover, Jose Maria; Konstandoulakis, Manoussos M; Kurtoglu, Mehmet; Lepäntalo, Mauri; Llort-Pont, Carme; Meneu-Diaz, Juan Carlos; Moreno-Gonzales, Enrique; Navarro-Soto, Salvador; Panoussis, P; Ryan, James M; Salenius, Juha P; Seccia, Massimo; Takolander, Rabbe; Taviloglu, Korhan; Tiesenhausen, Kurt; Torfason, Bjarni; Uranüs, Selman

2002-02-01

405

Recombinant human soluble thrombomodulin reduces endotoxin-induced pulmonary vascular injury via protein C activation in rats.  

PubMed

Adult respiratory distress syndrome (ARDS) is a serious complication of disseminated intravascular coagulation (DIC) or multiple organ failure. To determine whether recombinant soluble human thrombomodulin (rsTM) may be useful in treating ARDS due to sepsis, we investigated the effect of rsTM on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats. The intravenous administration of rsTM prevented the increase in pulmonary vascular permeability induced by LPS. Neither heparin plus antithrombin III (AT III) nor dansyl Glu Gly Arg chloromethyl ketone-treated factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, prevented LPS-induced vascular injury. The agents rsTM, heparin plus AT III, and DEGR-Xa all significantly inhibited the LPS-induced intravascular coagulation. Recombinant soluble TM pretreated with a monoclonal antibody (moAb) that inhibits protein C activation by rsTM did not prevent the LPS-induced vascular injury; in contrast, rsTM pretreated with a moAb that does not affect thrombin binding or protein C activation by rsTM prevented vascular injury. Administration of activated protein C (APC) also prevented vascular injury. LPS-induced pulmonary vascular injury was significantly reduced in rats with leukopenia induced by nitrogen mustard and by ONO-5046, a potent inhibitor of granulocyte elastase. Results suggest that rsTM prevents LPS-induced pulmonary vascular injury via protein C activation and that the APC-induced prevention of vascular injury is independent of its anticoagulant activity, but dependent on its ability to inhibit leukocyte activation. PMID:8607107

Uchiba, M; Okajima, K; Murakami, K; Nawa, K; Okabe, H; Takatsuki, K

1995-11-01

406

Preferential sorption versus preferential permeability in pervaporation  

Microsoft Academic Search

Transport of liquids by pervaporation takes place by a solution—diffusion mechanism. In order to investigate the “solution part” of this transport model, preferential sorption has been compared with preferential permeability. Sorption equilibria and pervaporation experiments for the systems water—ethanol—cellulose acetate, water—ethanol—polyacrylonitrile and water—ethanol—polysulfone have been investigated. Theoretical values of preferential sorption have been derived from Flory—Huggins thermodynamics, extended with concentration

M. H. V. Mulder; T. Franken; C. A. Smolders

1985-01-01

407

Methods of determining permeability, transmissibility and drawdown  

USGS Publications Warehouse

If the Theis graphical method is used for determining the hydraulic constants of an aquifer under water-table conditions, the observed drawdowns should be corrected for the decrease in saturated thickness. This is especially true if the drawdown is a large fraction of the original saturated thickness, for then the computed coefficient of permeability is highly inaccurate if based on observed, rather than corrected, water levels. Wenzel's limiting formula, a modification of the Theis graphical method, is useful where u=r2s/4Tt is less than about 0.01. However, a shorter procedure for determination of the coefficient of transmissibility, as well as the coefficient of storage, consists of plotting the values of the corrected drawdowns against the values of the logarithm of r. Wenzel (1942) suggested that observation wells be situated on lines that extend upgradient and downgradient from the pumped well. However, a detailed analysis of aquifer-test results indicates that such a restriction is unnecessary. The gradient method for determining permeability should yield the same results as the Thies method. The former, when applied for a distance within the range of applicability of the latter, is merely a duplication of effort or, at best, a crude check. Because of the limitations of accuracy in plotting, the gradient method is much less satisfactory. That Wenzel (1942) obtained identical results from the two methods is regarded as a coincidence. Failure to take into consideration the fact that the pumped well does not tap the full thickness of the aquifer leads to an apparent coefficient of permeability that is much too low, especially if the aquifer consists of stratified sediments. The average coefficient of permeability computed from uncorrected drawdowns may be only a little more than half of the true value.

Bentall, Ray

1964-01-01

408

In silico vs. in vivo human intestinal permeability.  

PubMed

The aim of this research is to calculate human intestinal permeability in silico and correlate results with those measured in vivo. Optimized human intestinal permeability values were calculated for 16 drugs by de-convolution of human plasma profiles using Parameter Estimation module of SimCYP program V13. Results showed high in silico-in vivo correlation coefficient of 0.89 for drugs with high/low permeability values. In silico permeability, if properly optimized, can be used as surrogate for in vivo permeability for BCS class I drugs and hence is suggested that such methodology could be employed as a support for waiver of in vivo studies. PMID:24515934

Idkaidek, N M; Najib, N

2014-12-01

409

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

410

Pressure Measurements across Vascular Stenoses  

PubMed Central

Summary We describe and analyze pressure measurements across vascular stenoses in an atherosclerotic human carotid bulb replica using catheters of different diameters. Replicas of an atherosclerotic human carotid bulb were created using the lost wax technique, and were placed in a circuit of pulsating non-newtonian fluid. Flows were adjusted to replicate human physiologic flow profiles. Common carotid artery total flow volume of 600 milliliters/minute was studied. A pressure recording device was calibrated; data were received from catheters placed longitudinally in the common carotid artery and internal carotid artery. The internal carotid artery pressures were obtained both through the stenosis as is usually performed in the angiography suite and through the vessel side-wall beyond the stenosis as a control. Internal carotid artery flow volumes were also measured with and without the catheter through the stenosis. Multiple pressure recordings and volume measurements were obtained in the replica using 7 French, 5 French, and 2.5 French catheters. Measurements of the replica showed a 58% diameter stenosis and an 89% area stenosis of the carotid bulb. All longitudinal pressure measurements in the common carotid artery agreed with control values regardless of the diameter of the catheter used. Pressure measurements were also in agreement with control values in the internal carotid artery using the 2.5 French catheter. However; when larger diameter catheters were employed, pressures measured with the catheter through the stenosis fell when compared to control values. Additionally, internal carotid artery flow volumes were also decreased when the larger diameter catheters were placed across the stenosis. Large diameter catheters when placed across vascular stenoses may cause an occlusive or near-occlusive state and artifactually increase the measured transstenotic vascular pressure gradient as well as decrease forward vascular flow. PMID:20670502

Imbesi, S.G.; Kerber, C.W.

1999-01-01

411

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