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1

Monitoring pulmonary vascular permeability using radiolabeled transferrin  

SciTech Connect

A simple, noninvasive technique for monitoring pulmonary vascular permeability in patients in critical care units is discussed. High vascular permeability is observed in patients with clinically defined adult respiratory distress syndrome (ARDS) but not in patients with hydrostatic pulmonary edema or in patients with minor pulmonary insults who are considered to be at risk of developing ARDS. The technique has been used in the field of therapeutics and pharmacology to test the effects of the putative antipermeability agents methylprednisolone and terbutaline sulfate. There appears to be a good correlation between the acute inhibitory effect of either drug on transferrin exudation and patient prognosis. Thus, a byproduct of such drug studies may be an index of survival in patients with established ARDS.

Basran, G.S.; Hardy, J.G.

1988-07-01

2

Animal Models of Increased Lung Vascular Permeability  

Microsoft Academic Search

\\u000a The pulmonary microvascular endothelium regulates vascular water and solute flux into tissues. Vascular barrier function is\\u000a physically established by tight junctions and adherens junctions between neighboring endothelial cells. Endothelial permeability\\u000a together with vascular oncotic and hydrostatic pressures control fluid and solute movement into the pulmonary interstitium\\u000a via paracellular and transcellular pathways. Transvascular fluid flux into the interstitium is constantly counteracted

Sara Hanif Mirza; M. Kamran Mirza; Asrar B. Malik

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

Brief Communication Determination of vascular permeability coefficients under slow  

E-print Network

Brief Communication Determination of vascular permeability coefficients under slow luminal filling, Boston, MA 02215, USA a b s t r a c ta r t i c l e i n f o Article history: Accepted 12 July 2013 (permeability coefficient normalized by vascular dimensions) from time-lapse intensity data for which

Tien, Joe

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

Vascular Permeability Factor, an Endothelial Cell Mitogen Related to PDGF  

Microsoft Academic Search

Vascular permeability factor (VPF) is a 40-kilodalton disulfide-linked dimeric glycoprotein that is active in increasing blood vessel permeability, endothelial cell growth, and angiogenesis. These properties suggest that the expression of VPF by tumor cells could contribute to the increased neovascularization and vessel permeability that are associated with tumor vasculature. The cDNA sequence of VPF from human U937 cells was shown

Pamela J. Keck; Scott D. Hauser; Gwen Krivi; Kim Sanzo; Thomas Warren; Joseph Feder; Daniel T. Connolly

1989-01-01

7

Vascular permeability of spinal nerve roots  

Microsoft Academic Search

The permeability of blood vessels in rat spinal nerve roots was investigated with Evans blue-albumin as an in vivo macromolecular tracer and lanthanum as tracers as an electron microscopic ionic marker added to a fixative. Rats injected intravenously with Evans blue, showed macroscopic distinct staining of dorsal root ganglia, whereas spinal nerve roots remained unstained. Fluorescence microscopy, however, revealed clear

C. Å. V. Pettersson; H. S. Sharma; Y. Olsson

1990-01-01

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

Visualizing vascular permeability and lymphatic drainage using labeled serum albumin  

PubMed Central

During the early stages of angiogenesis, following stimulation of endothelial cells by vascular endothelial growth factor (VEGF), the vascular wall is breached, allowing high molecular weight proteins to leak from the vessels to the interstitial space. This hallmark of angiogenesis results in deposition of a provisional matrix, elevation of the interstitial pressure and induction of interstitial convection. Albumin, the major plasma protein appears to be an innocent bystander that is significantly affected by these changes, and thus can be used as a biomarker for vascular permeability associated with angiogenesis. Traditionally, albumin leak in superficial organs was followed by colorimetry or morphometry with the use of albumin binding vital dyes. Over the last years, the introduction of tagged-albumin that can be detected by various imaging methods, such as magnetic resonance imaging and positron emission tomography, opened new possibilities for quantitative three dimension dynamic analysis of permeability in any organ. Using these tools it is now possible to follow not only vascular permeability, but also interstitial convection and lymphatic drain. Active uptake of tagged albumin by caveolae-mediated endocytosis opens the possibility for using labeled albumin for vital staining of cells and cell tracking. This approach was used for monitoring recruitment of perivascular stroma fibroblasts associated with tumor angiogenesis. PMID:20512410

Vandoorne, Katrien; Addadi, Yoseph

2010-01-01

10

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

11

Mechanism of dexamethasone suppression of brain tumor-associated vascular permeability in rats. Involvement of the glucocorticoid receptor and vascular permeability factor.  

PubMed Central

Brain tumor-associated cerebral edema arises because tumor capillaries lack normal blood-brain barrier function; vascular permeability factor (VPF, also known as vascular endothelial growth factor, VEGF) is a likely mediator of this phenomenon. Clinically, dexamethasone reduces brain tumor-associated vascular permeability through poorly understood mechanisms. Our goals were to determine if suppression of permeability by dexamethasone might involve inhibition of VPF action or expression, and if dexamethasone effects in this setting are mediated by the glucocorticoid receptor (GR). In two rat models of permeability (peripheral vascular permeability induced by intradermal injection of 9L glioma cell-conditioned medium or purified VPF, and intracerebral vascular permeability induced by implanted 9L glioma), dexamethasone suppressed permeability in a dose-dependent manner. Since 80% of the permeability-inducing activity in 9L-conditioned medium was removed by anti-VPF antibodies, we examined dexamethasone effects of VPF expression in 9L cells. Dexamethasone inhibited FCS- and PDGF-dependent induction of VPF expression. At all levels (intradermal, intracranial, and cell culture), dexamethasone effects were reversed by the GR antagonist mifepristone (RU486). Dexamethasone may decrease brain tumor-associated vascular permeability by two GR-dependent mechanisms: reduction of the response of the vasculature to tumor-derived permeability factors (including VPF), and reduction of VPF expression by tumor cells. PMID:8823305

Heiss, J D; Papavassiliou, E; Merrill, M J; Nieman, L; Knightly, J J; Walbridge, S; Edwards, N A; Oldfield, E H

1996-01-01

12

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

Microsoft Academic Search

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

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

2010-01-01

13

New sensitive fluorometric method for measurement of vascular permeability  

SciTech Connect

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

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

1984-06-01

14

Non-invasive optical modulation of local vascular permeability  

NASA Astrophysics Data System (ADS)

For a systemically administered drug to act, it first needs to cross the vascular wall. This step represents a bottleneck for drug development, especially in the brain or retina, where tight junctions between endothelial cells form physiological barriers. Here, we demonstrate that femtosecond pulsed laser irradiation focused on the blood vessel wall induces transient permeabilization of plasma. Nonlinear absorption of the pulsed laser enabled the noninvasive modulation of vascular permeability with high spatial selectivity in three dimensions. By combining this method with systemic injection, we could locally deliver molecular probes in various tissues, such as brain cortex, meninges, ear, striated muscle, and bone. We suggest this method as a novel delivery tool for molecular probes or drugs.

Choi, Myunghwan; Choi, Chulhee

2011-03-01

15

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

16

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

17

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

18

Progesterone Receptor in the Vascular Endothelium Triggers Physiological Uterine Permeability Pre-implantation  

PubMed Central

Summary Vascular permeability is frequently associated with inflammation and triggered by a cohort of secreted permeability factors such as VEGF. Here we show that the physiological vascular permeability that precedes implantation is directly controlled by progesterone receptor (PR) and is independent of VEGF. Both global and endothelial-specific deletion of PR block 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 ChIP-sequencing revealed that PR induces a 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 to 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; 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

2014-01-01

19

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

20

THE EVALUATION OF INCREASED VASCULAR PERMEABILITY IN THE SKIN OF GUINEA-PIGS  

Microsoft Academic Search

The increases in vascular permeability induced by the intracutaneous injection of histamine, compound 48\\/80, polymyxin B, bradykinin, globulin permeability factor and kallikrein were compared in the skin of the dorsal trunk of guinea-pigs with Evans blue circulating in their blood. With respect to log dose injected, the response in treated sites was evaluated in three ways: (1) diameter of the

Jean Carr; DL Wilhelm

1964-01-01

21

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

22

Vascular permeability factor/vascular endothelial growth factor, microvascular hyperpermeability, and angiogenesis.  

PubMed Central

VPF/VEGF is a multifunctional cytokine that contributes to angiogenesis by both direct and indirect mechanisms. On the one hand, VPF/VEGF stimulates the ECs lining nearby microvessels to proliferate, to migrate, and to alter their pattern of gene expression. On the other hand, VPF/VEGF renders these same microvascular ECs hyperpermeable so that they spill plasma proteins into the extravascular space, leading to the clotting of extravasated fibrinogen with deposition of a fibrin gel. Extravascular fibrin serves as a provisional matrix that favors and supports the ingrowth of new blood vessels and other mesenchymal cells that generate mature, vascularized stroma. These same principles apply in tumors, in several examples of non-neoplastic pathology, and in physiological processes that involve angiogenesis and new stroma generation. In all of these examples, microvascular hyperpermeability and the introduction of a provisional, plasma-derived matrix precede and accompany the onset of EC division and new blood vessel formation. It would seem, therefore, that tumors have "borrowed" fundamental mechanisms that developed in multicellular organisms for purposes of tissue defense, renewal, and repair. VPF/VEGF, therefore has taught us something new about angiogenesis; namely, that vascular hyperpermeability and consequent plasma protein extravasation are important, perhaps essential, elements in its generation. However, this finding raises a paradox. While VPF/VEGF induces vascular hyperpermeability, other potent angiogenic factors apparently do not, at least in subtoxic concentrations that are more than sufficient to induce angiogenesis. Nonetheless, wherever angiogenesis has been studied, the newly generated vessels have been found to be hyperpermeable. How, therefore, do angiogenic factors other than VPF/VEGF lead to the formation of new and leaky blood vessels? We do not as yet have a complete answer to this question. One possibility is that at least some angiogenic factors mediate their effect by inducing or stimulating the expression of VPF/VEGF. In fact, there is already one clear example of this. TGF-alpha is a potent angiogenic factor but does not itself increase microvascular permeability. However, TGF-alpha strikingly upregulates VPF/VEGF expression in cultured keratinocytes and is thought to be responsible, at least in part, for the overexpression of VPF/VEGF in psoriasis. Moreover, overexpression of TGF-alpha, along with that of the EGF receptor with which it interacts, is characteristic of many malignant tumors, raising the possibility that TGF-alpha acts to stimulate VPF/VEGF expression in other types of epithelial cells and in this manner induces angiogenesis.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7538264

Dvorak, H. F.; Brown, L. F.; Detmar, M.; Dvorak, A. M.

1995-01-01

23

Augmentation of vascular permeability of VEGF is enhanced by KDR-binding proteins.  

PubMed

VEGF165 is a key regulator of angiogenesis and a potent vascular permeability factor. Using snake venom proteins as tools, we demonstrate the enhanced vascular leakage of VEGF by KDR-binding proteins. The snake venom-derived KDR-specific VEGF, vammin, potently enhanced vascular leakage compared with other known permeability-enhancing factors including VEGF165, while KDR-bp from snake venom, a KDR antagonist of endothelial cell growth was a very weak permeability enhancer. Unexpectedly when co-administrated, KDR-bp synergistically enhanced either vammin or VEGF165-stimulated vascular leakage, despite its antagonistic effect on cell growth. This augmenting effect was specifically observed in the combined administration of KDR-bp with either VEGF165 or vammin, but not other combination of known permeability-enhancing factors. We further demonstrated a similar increased vascular leakage by the combined administration of VEGF165 and TIMP-3, the only known endogenous antagonist of KDR. Our findings implicate TIMP-3 as a critical player in the vascular leakage-enhancing effect of VEGF165 in vivo. PMID:17320821

Yamazaki, Yasuo; Nakano, Yuta; Imamura, Takahisa; Morita, Takashi

2007-04-13

24

Visualizing vascular permeability and lymphatic drainage using labeled serum albumin  

Microsoft Academic Search

During the early stages of angiogenesis, following stimulation of endothelial cells by vascular endothelial growth factor\\u000a (VEGF), the vascular wall is breached, allowing high molecular weight proteins to leak from the vessels to the interstitial\\u000a space. This hallmark of angiogenesis results in deposition of a provisional matrix, elevation of the interstitial pressure\\u000a and induction of interstitial convection. Albumin, the major

Katrien Vandoorne; Yoseph Addadi; Michal Neeman

2010-01-01

25

C1 inhibitor prevents Gram-negative bacterial lipopolysaccharide-induced vascular permeability  

Microsoft Academic Search

Gram-negative bacterial endotoxemia may lead to the pathological increase of vascu- lar permeability with systemic vascular collapse, a vascular leak syndrome, mul- tiple organ failure (MOF), and\\/or shock. Previous studies demonstrated that C1 inhibitor (C1INH) protects mice from lipo- polysaccharide (LPS)-induced lethal sep- tic shock via a direct interaction with LPS. Here, we report that C1INH blocked the LPS-induced increase

Dongxu Liu; Dong Zhang; Jennifer Scafidi; Xiao Wu; Cort C. Cramer; Alvin E. Davis

26

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

PubMed Central

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

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

2010-01-01

27

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

28

The induction of nitric oxide synthase and intestinal vascular permeability by endotoxin in the rat.  

PubMed Central

1. The effect of endotoxin (E. coli lipopolysaccharide) on the induction of nitric oxide synthase (NOS) and the changes in vascular permeability in the colon and jejunum over a 5 h period have been investigated in the rat. 2. Under resting conditions, a calcium-dependent constitutive NOS, determined by the conversion of radiolabelled L-arginine to citrulline, was detected in homogenates of both colonic and jejunal tissue. 3. Administration of endotoxin (3 mg kg-1, i.v.) led, after a 2 h lag period, to the appearance of calcium-independent NOS activity in the colon and jejunum ex vivo, characteristic of the inducible NOS enzyme. 4. Administration of endotoxin led to an increase in colonic and jejunal vascular permeability after a lag period of 3 h, determined by the leakage of radiolabelled albumin. 5. Pretreatment with dexamethasone (1 mg kg-1 s.c., 2 h prior to challenge) inhibited both the induction of NOS and the vascular leakage induced by endotoxin. 6. Administration of the NO synthase inhibitor NG-monomethyl-L-arginine (12.5-50 mg kg-1, s.c.) 3 h after endotoxin injection, dose-dependently reduced the subsequent increase in vascular permeability in jejunum and colon, an effect reversed by L-arginine (300 mg kg-1, s.c.). 7. These findings suggest that induction of NOS is associated with the vascular injury induced by endotoxin in the rat colon and jejunum. PMID:7507778

Boughton-Smith, N. K.; Evans, S. M.; Laszlo, F.; Whittle, B. J.; Moncada, S.

1993-01-01

29

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

30

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

31

Src regulates angiogenic factors and vascular permeability after focal cerebral ischemia-reperfusion  

PubMed Central

Developing new strategies to treat cerebral ischemic-reperfusion injury will require a better understanding of the mechanisms that underlie vascular permeability. In this study we examined the temporal expression of Src and angiogenic factors in rat brain after focal cerebral ischemia and reperfusion and analyzed the relationships among those factors. We also investigated the effect of Src inhibitor PP1 in ischemic reperfusion. Rats were subjected to middle cerebral artery occlusion for 90 min followed by reperfusion with or without PP1 treatment. Src mRNA increased at 3 h after reperfusion and then gradually declined. Phosphorylation of Src at Y418 displayed a biphasic increase. Phosphorylation increased as early as 3 h and peaked at 6 h; after decreasing, it peaked again at 3 to 7 days. Increases in Src mRNA and phosphorylation correlated positively with levels of vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2), and negatively with levels of angiopoietin-1 (Ang-1) and zonula occludens-1 (ZO-1). Changes in the expression of these factors correlated with the progress of vascular permeability, especially early after reperfusion. Hence, dynamic temporal changes in Src Y418 phosphorylation may modulate vascular permeability after cerebral ischemia and reperfusion. PP1 effectively decreased Src Y418 phosphorylation and the expression of VEGF and Ang-2 and increased the expression of Ang-1 and ZO-1. It also reduced cerebral infarct size and neurologic dysfunction. Therefore, Src may represent a new therapeutic target for reducing tissue damage caused by increased vascular permeability. PMID:24412374

Zan, Likun; Zhang, Xin; Xi, Yanfeng; Wu, He; Song, Yuejia; Teng, Guoxin; Li, Heng; Qi, Jiping; Wang, Jian

2014-01-01

32

Src regulates angiogenic factors and vascular permeability after focal cerebral ischemia-reperfusion.  

PubMed

Developing new strategies to treat cerebral ischemic-reperfusion injury will require a better understanding of the mechanisms that underlie vascular permeability. In this study we examined the temporal expression of Src and angiogenic factors in rat brain after focal cerebral ischemia and reperfusion and analyzed the relationships among those factors. We also investigated the effect of Src inhibitor PP1 (4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine) in ischemic reperfusion. Rats were subjected to middle cerebral artery occlusion for 90 min followed by reperfusion with or without PP1 treatment. Src mRNA increased at 3h after reperfusion and then gradually declined. Phosphorylation of Src at Y418 displayed a biphasic increase. Phosphorylation increased as early as 3h and peaked at 6h; after decreasing, it peaked again at 3-7 days. Increases in Src mRNA and phosphorylation correlated positively with levels of vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2), and negatively with levels of angiopoietin-1 (Ang-1) and zonula occludens-1 (ZO-1). Changes in the expression of these factors correlated with the progress of vascular permeability, especially early after reperfusion. Hence, dynamic temporal changes in Src Y418 phosphorylation may modulate vascular permeability after cerebral ischemia and reperfusion. PP1 effectively decreased Src Y418 phosphorylation and the expression of VEGF and Ang-2 and increased the expression of Ang-1 and ZO-1. It also reduced cerebral infarct size and neurologic dysfunction. Therefore, Src may represent a new therapeutic target for reducing tissue damage caused by increased vascular permeability. PMID:24412374

Zan, L; Zhang, X; Xi, Y; Wu, H; Song, Y; Teng, G; Li, H; Qi, J; Wang, J

2014-03-14

33

Glycocalyx and sepsis-induced alterations in vascular permeability.  

PubMed

Endothelial cells line the inner portion of the heart, blood vessels, and lymphatic vessels; a basal membrane of extracellular matrix lines the extraluminal side of endothelial cells. The apical side of endothelial cells is the site for the glycocalyx, which is a complex network of macromolecules, including cell-bound proteoglycans and sialoproteins. Sepsis-associated alterations of this structure may compromise endothelial permeability with associated interstitial fluid shift and generalized edema. Indeed, in sepsis, the glycocalyx acts as a target for inflammatory mediators and leukocytes, and its ubiquitous nature explains the damage of tissues that occurs distant from the original site of infection. Inflammatory-mediated injury to glycocalyx can be responsible for a number of specific clinical effects of sepsis, including acute kidney injury, respiratory failure, and hepatic dysfunction. Moreover, some markers of glycocalyx degradation, such as circulating levels of syndecan or selectins, may be used as markers of endothelial dysfunction and sepsis severity. Although a great deal of experimental evidence shows that alteration of glycocalyx is widely involved in endothelial damage caused by sepsis, therapeutic strategies aiming at preserving its integrity did not significantly improve the outcome of these patients. PMID:25777848

Chelazzi, Cosimo; Villa, Gianluca; Mancinelli, Paola; De Gaudio, A Raffaele; Adembri, Chiara

2015-12-01

34

Intra-arterial delivery of triolein emulsion increases vascular permeability in skeletal muscles of rabbits  

PubMed Central

Background To test the hypothesis that triolein emulsion will increase vascular permeability of skeletal muscle. Methods Triolein emulsion was infused into the superficial femoral artery in rabbits (triolein group, n = 12). As a control, saline was infused (saline group, n = 18). Pre- and post-contrast T1-weighted MR images were obtained two hours after infusion. The MR images were qualitatively and quantitatively evaluated by assessing the contrast enhancement of the ipsilateral muscles. Histologic examination was performed in all rabbits. Results The ipsilateral muscles of the rabbits in the triolein group showed contrast enhancement, as opposed to in the ipsilateral muscles of the rabbits in the saline group. The contrast enhancement of the lesions was statistically significant (p < 0.001). Histologic findings showed that most examination areas of the triolein and saline groups had a normal appearance. Conclusion Rabbit thigh muscle revealed significantly increased vascular permeability with triolein emulsion; this was clearly demonstrated on the postcontrast MR images. PMID:19604410

Kim, Hak Jin; Kim, Yong Woo; Lee, In Sook; Song, Jong Woon; Jeong, Yeon Joo; Choi, Seon Hee; Choi, Kyung Un; Suh, Kuen Tak; Cho, Byung Mann

2009-01-01

35

Vascular permeability and microcirculation of gliomas and mammary carcinomas transplanted in rat and mouse cranial windows.  

PubMed

Many brain tumors are highly resistant to chemotherapy, presumably due to the presence of a tight blood-tumor barrier. For a better understanding of the regulation of this barrier by the brain environment, a new intravital microscopy model was established by transplanting tumor tissue into cranial windows in both rats and mice. The model was characterized by RBC velocities, vessel diameters, and vascular permeabilities of various tumors: R3230AC (a rat mammary adenocarcinoma), MCaIV (a mouse mammary adenocarcinoma), and U87 and HGL21 (human malignant astrocytomas). Our results showed that tumor blood flow in cranial windows was one to three orders of magnitude lower than the blood flow in pial vessels and similar to that in dorsal skin-fold chambers observed in previous studies. The mean vessel diameter ranged from 6.8 +/- 1.3 microns for HGL21 to 30.4 +/- 8.5 microns for MCaIV. At least one order of magnitude difference in vascular permeability to albumin was observed between tumor lines: 0.11 +/- 0.05 x 10(-7) cm/s for HGL21 versus 3.8 +/- 1.2 x 10(-7) cm/s for U87. The low vascular permeability of HGL21, which was also confirmed by both sodium fluorescein and Lissamine green injections, suggests that not all tumors are leaky to tracer molecules and that the blood-tumor barrier of this tumor still possesses some characteristics of blood-brain barrier as observed in other intracranial tumors. The model presented here will allow us to manipulate the vascular permeability in brain tumors and thus may provide new information on the regulation of the blood-tumor barrier and new strategies for improving drug delivery in brain tumors. PMID:8062241

Yuan, F; Salehi, H A; Boucher, Y; Vasthare, U S; Tuma, R F; Jain, R K

1994-09-01

36

Inhibition of vascular permeability by antisense-mediated inhibition of plasma kallikrein and coagulation factor 12.  

PubMed

Hereditary angioedema (HAE) is a rare disorder characterized by recurrent, acute, and painful episodes of swelling involving multiple tissues. Deficiency or malfunction of the serine protease inhibitor C1 esterase inhibitor (C1-INH) results in HAE types 1 and 2, respectively, whereas mutations in coagulation factor 12 (f12) have been associated with HAE type 3. C1-INH is the primary inhibitor of multiple plasma cascade pathways known to be altered in HAE patients, including the complement, fibrinolytic, coagulation, and kinin-kallikrein pathways. We have selectively inhibited several components of both the kinin-kallikrein system and the coagulation cascades with potent and selective antisense oligonucleotides (ASOs) to investigate their relative contributions to vascular permeability. We have also developed ASO inhibitors of C1-INH and characterized their effects on vascular permeability in mice as an inducible model of HAE. Our studies demonstrate that ASO-mediated reduction in C1-INH plasma levels results in increased vascular permeability and that inhibition of proteases of the kinin-kallikrein system, either f12 or prekallikrein (PKK) reverse the effects of C1-INH depletion with similar effects on both basal and angiotensin converting enzyme (ACE) inhibitor-induced permeability. In contrast, inhibition of coagulation factors 11 (f11) or 7 (f7) had no effect. These results suggest that the vascular defects observed in C1-INH deficiency are dependent on the kinin-kallikrein system proteases f12 and PKK, and not mediated through the coagulation pathways. In addition, our results highlight a novel therapeutic modality that can potentially be employed prophylactically to prevent attacks in HAE patients. PMID:23582057

Bhattacharjee, Gourab; Revenko, Alexey S; Crosby, Jeffrey R; May, Chris; Gao, Dacao; Zhao, Chenguang; Monia, Brett P; MacLeod, A Robert

2013-06-01

37

Intravital analysis of vascular permeability in mice using two-photon microscopy.  

PubMed

Blood vessel endothelium forms a semi-permeable barrier and its permeability controls the traffics of plasma contents. Here we report an intravital evaluation system for vascular permeability in mice using two-photon microscopy. We used various sizes of fluorescein-conjugated dextran as a tracer and its efflux was quantified by measuring the changes of fluorescent intensity both on the blood vessel area and the interstitial space. Using this system, we demonstrated that skin blood vessels limited the passage of dextran larger than 70 kDa under homeostatic conditions. We evaluated the kinetics of vascular permeability in histamine- or IgE-induced type I allergic models and a hapten-induced type IV allergic model. In such inflammatory conditions, the hyperpermeability was selectively induced in the postcapillary venules and dextran as large as 2000-kDa leaked from the bloods. Taken together, our study provides a convenient method to characterize the skin blood vessels as a traffic barrier in physiological conditions. PMID:23732999

Egawa, Gyohei; Nakamizo, Satoshi; Natsuaki, Yohei; Doi, Hiromi; Miyachi, Yoshiki; Kabashima, Kenji

2013-01-01

38

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

39

Increased pulmonary vascular permeability as a cause of re-expansion edema in rabbits  

SciTech Connect

In order to study the mechanism(s) underlying re-expansion edema, we measured the concentration of labeled albumin (RISA) in the extravascular, extracellular water (EVECW) of the lung as a measure of pulmonary vascular permeability. Re-expansion edema was first induced by rapid re-expansion of rabbit lungs that had been collapsed for 1 wk by pneumothorax. The RISA in EVECW was expressed as a fraction of its plasma concentration: (RISA)L/(RISA)PL. The volume of EVECW (ml/gm dry lung) was measured using a /sup 24/Na indicator. Results in re-expansion edema were compared with normal control lungs and with oleic acid edema as a model of permeability edema. In re-expanded lungs, EVECW (3.41 +/- SD 1.24 ml/g) and (RISA)L/(RISA)PL 0.84 +/- SD 0.15) were significantly increased when compared with normal control lungs (2.25 +/- 0.41 ml/g and 0.51 +/- 0.20, respectively). Results in oleic acid edema (5.66 +/- 2.23 ml/g and 0.84 +/- 0.23) were similar to re-expansion edema. This suggested that re-expansion edema is due to increased pulmonary vascular permeability caused by mechanical stresses applied to the lung during re-expansion.

Pavlin, D.J.; Nessly, M.L.; Cheney, F.W.

1981-01-01

40

A Bayesian Image Analysis of Radiation Induced Changes in Tumor Vascular Permeability  

PubMed Central

Summary This work is motivated by a quantitative Magnetic Resonance Imaging study of the relative change in tumor vascular permeability during the course of radiation therapy. The differences in tumor and healthy brain tissue physiology and pathology constitute a notable feature of the image data—spatial heterogeneity with respect to its contrast uptake profile (a surrogate for permeability) and radiation induced changes in this profile. To account for these spatial aspects of the data, we employ a Gaussian hidden Markov random field (MRF) model. The model incorporates a latent set of discrete labels from the MRF governed by a spatial regularization parameter. We estimate the MRF regularization parameter and treat the number of MRF states as a random variable and estimate it via a reversible jump Markov chain Monte Carlo algorithm. We conduct simulation studies to examine the performance of the model and compare it with a recently proposed method using the Expectation-Maximization (EM) algorithm. Simulation results show that the Bayesian algorithm performs as well, if not slightly better than the EM based algorithm. Results on real data suggest that the tumor “core” vascular permeability increases relative to healthy tissue three weeks after starting radiotherapy, which may be an opportune time to initiate chemotherapy and warrants further investigation. PMID:20448832

Zhang, Xiaoxi; Johnson, Timothy D.; Little, Roderick J. A.; Cao, Yue

2010-01-01

41

Measurements of pulmonary vascular permeability with PET and gallium-68 transferrin  

SciTech Connect

We quantified pulmonary vascular permeability with positron emission tomography (PET) and gallium-68-(/sup 68/Ga) labeled transferrin. Six dogs with oleic acid-induced lung injury confined to the left lower lobe, two normal human volunteers, and two patients with the adult respiratory distress syndrome (ARDS) were evaluated. Lung tissue-activity measurements were obtained from sequential 1-5 min PET scans collected over 60 min, after in vivo labeling of transferrin through intravenous administration of (/sup 68/Ga)citrate. Blood-activity measurements were measured from simultaneously obtained peripheral blood samples. A forward rate constant describing the movement of transferrin from pulmonary vascular to extravascular compartments, the pulmonary transcapillary escape rate (PTCER), was then calculated from these data using a two-compartment model. In dogs, PTCER was 49 +/- 18 in normal lung tissue and 485 +/- 114 10(-4) min-1 in injured lung. A repeat study in these dogs 4 hr later showed no significant change. Values in the human subjects showed similarly marked differences between normal and abnormal lung tissue. We conclude that PET will be a useful method of evaluating vascular permeability changes after acute lung injury.

Mintun, M.A.; Dennis, D.R.; Welch, M.J.; Mathias, C.J.; Schuster, D.P.

1987-11-01

42

A neurodegenerative vascular burden index and the impact on cognition.  

PubMed

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

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

2014-01-01

43

A Neurodegenerative Vascular Burden Index and the Impact on Cognition  

PubMed Central

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

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

2014-01-01

44

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

45

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

PubMed Central

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

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

2013-01-01

46

The Minimum Percentage of Triolein Emulsion for Studying Cerebral Vascular Permeability with Least Brain Edema  

PubMed Central

Background: Triolein emulsion infusion into the brain produces transiently increased vascular permeability. Objectives: The purpose of this study was to find the minimum percentage of triolein emulsion required for studying vascular permeability with minimal brain edema. Materials and Methods: Sixty healthy cats were divided into six groups according to the concentration of emulsified triolein infused into the carotid artery: group 1, 0.125% (n = 10); group 2, 0.25% (n = 10); group 3, 0.5% (n = 10); group 4, 1% (n = 10); group 5, 2% (n = 10); and group 6, saline infusion (control group, n = 10). T2-, T1- and contrast enhanced T1-weighted MR images were obtained 2 hours after infusing triolein emulsion. Contrast enhancement ratios (CERs) and signal intensity ratios (SIRs) versus contralateral hemispheres were calculated. Statistical analysis was performed by analysis of variance followed by Tukey’s test. P values of ? 0.05 were considered significant. Results: The lesion hemispheres showed mild hyperintensity due to edema on T2-weighted images, and contrast enhancement on post-contrast T1-weighted images in cats of group 1-5. CERs showed statistically significant differences between the control group and group 3 (P = 0.006), group 4 (P = 0.003), and group 5 (P < 0.001). However, SIRs were significantly different between the control group and group 5 only (P < 0.001). Conclusion: The minimum concentration of triolein emulsion required to increase vascular permeability adequately with minimal brain edema in a cat model was 0.5%. PMID:25780547

Choi, Seon Hee; Kim, Hak Jin; Hwangbo, Lee; Kim, Yong-Woo

2014-01-01

47

Increased vascular permeability, angiogenesis and wound healing induced by the serum of natural latex of the rubber tree Hevea brasiliensis.  

PubMed

Increases in vascular permeability and angiogenesis are crucial events to wound repair, tumoral growth and revascularization of tissues submitted to ischemia. An increased vascular permeability allows a variety of cytokines and growth factors to reach the damaged tissue. Nevertheless, the angiogenesis supply tissues with a wide variety of nutrients and is also important to metabolites clearance. It has been suggested that the natural latex from Hevea brasiliensis showed wound healing properties and angiogenic activity. Thus, the purpose of this work was to characterize its angiogenic activity and its effects on vascular permeability and wound healing. The serum fraction of the latex was separated from the rubber with reduction of the pH. The activity of the dialyzed serum fraction on the vascular permeability injected in subcutaneous tissue was assayed according Mile's method. The angiogenic activity was determined using a chick embryo chorioallantoic membrane assay and its effects on the wound-healing process was determined by the rabbit ear dermal ulcer model. The serum fraction showed evident angiogenic effect and it was effective in enhancing vascular permeability. In dermal ulcers, this material significantly accelerated wound healing. Moreover, the serum fraction boiled and treated with proteases lost these activities. These results are in accordance with the enhancement of wound healing observed in clinical trials carried out with a biomembrane prepared with the same natural latex. PMID:19943314

Mendonça, Ricardo José; Maurício, Vanessa Beatriz; Teixeira, Larissa de Bortolli; Lachat, João José; Coutinho-Netto, Joaquim

2010-05-01

48

Tissue differences in vascular permeability induced by leukotriene B4 and prostaglandin E2 in the rat  

SciTech Connect

The activity of synthetic LTB4 and PGE2, in increasing vascular permeability was tested simultaneously in seventeen different organs in the rat. Rats were injected in the aortic arch through a cannula in the carotid artery with /sup 125/I-albumin, /sup 51/Cr-erythrocytes, and /sup 57/Co-EDTA. The rats were then injected through the carotid artery cannula with LTB4, PGE2 or a combination of LTB4 and PGE2. Eight minutes later the rats were killed and the activity of /sup 125/I, /sup 51/Cr, and /sup 57/Co measured in different organs. Changes in vascular permeability were inferred from changes in the ratios of the isotope activities. LTB4 (15 micrograms/kg) induced enhanced permeability in caecum, small bowel, skin, fat pad, stomach, pancreas, and aorta, but not in the heart, brain, colon, testes, diaphragm, forelimb, cremaster muscle, lung, kidney or eye. A lower dose of LTB4, 3 micrograms/kg, enhanced vascular permeability in caecum, small bowel, skin, stomach, and aorta. PGE2 (1 microgram/kg) enhanced vascular permeability only in the caecum. A combination of LTB4 (3 micrograms/kg) and PGE2 (1 microgram/kg) was more potent than either alone. Rats depleted of neutrophils with anti-neutrophil serum were less sensitive to LTB4 than intact rats. These findings suggest that the vasculatures of different tissues in the rat vary markedly in their susceptibility to LTB4 induced increases in permeability.

Stenson, W.F.; Chang, K.; Williamson, J.R.

1986-07-01

49

Ischemia–reperfusion injury induces occludin phosphorylation/ubiquitination and retinal vascular permeability in a VEGFR-2-dependent manner  

PubMed Central

Retinal ischemia–reperfusion (IR) induces neurodegenaration as well as blood–retinal barrier (BRB) breakdown causing vascular permeability. Whereas the neuronal death has been extensively studied, the molecular mechanisms related to BRB breakdown in IR injury remain poorly understood. In this study, we investigated the early changes in tight junctional (TJ) proteins in response to IR injury. Ischemia–reperfusion injury was induced in male rat retinas by increasing the intraocular pressure for 45?minutes followed by natural reperfusion. The results demonstrate that IR injury induced occludin Ser490 phosphorylation and ubiquitination within 15?minutes of reperfusion with subsequent vascular permeability. Immunohistochemical analysis revealed a rapid increase in occludin Ser490 phosphorylation and loss of Zonula occludens-1 (ZO-1) protein, particularly in arterioles. Ischemia–reperfusion injury also rapidly induced the activation and phosphorylation of vascular endothelial growth factor receptor-2 (VEGFR-2) at tyrosine 1175. Blocking vascular endothelial growth factor (VEGF) function by intravitreal injection of bevacizumab prevented VEGFR-2 activation, occludin phosphorylation, and vascular permeability. These studies suggest a novel mechanism of occludin Ser490 phosphorylation and ubiquitination downstream of VEGFR2 activation associated with early IR-induced vascular permeability. PMID:24398936

Muthusamy, Arivalagan; Lin, Cheng-Mao; Shanmugam, Sumathi; Lindner, Heather M; Abcouwer, Steven F; Antonetti, David A

2014-01-01

50

Minocycline prevents retinal inflammation and vascular permeability following ischemia-reperfusion injury  

PubMed Central

Background Many retinal diseases are associated with vascular dysfunction accompanied by neuroinflammation. We examined the ability of minocycline (Mino), a tetracycline derivative with anti-inflammatory and neuroprotective properties, to prevent vascular permeability and inflammation following retinal ischemia-reperfusion (IR) injury, a model of retinal neurodegeneration with breakdown of the blood-retinal barrier (BRB). Methods Male Sprague–Dawley rats were subjected to 45 min of pressure-induced retinal ischemia, with the contralateral eye serving as control. Rats were treated with Mino prior to and following IR. At 48 h after reperfusion, retinal gene expression, cellular inflammation, Evan’s blue dye leakage, tight junction protein organization, caspase-3 activation, and DNA fragmentation were measured. Cellular inflammation was quantified by flow-cytometric evaluation of retinal tissue using the myeloid marker CD11b and leukocyte common antigen CD45 to differentiate and quantify CD11b+/CD45low microglia, CD11b+/CD45hi myeloid leukocytes and CD11bneg/CD45hi lymphocytes. Major histocompatibility complex class II (MHCII) immunoreactivity was used to determine the inflammatory state of these cells. Results Mino treatment significantly inhibited IR-induced retinal vascular permeability and disruption of tight junction organization. Retinal IR injury significantly altered mRNA expression for 21 of 25 inflammation- and gliosis-related genes examined. Of these, Mino treatment effectively attenuated IR-induced expression of lipocalin 2 (LCN2), serpin peptidase inhibitor clade A member 3 N (SERPINA3N), TNF receptor superfamily member 12A (TNFRSF12A), monocyte chemoattractant-1 (MCP-1, CCL2) and intercellular adhesion molecule-1 (ICAM-1). A marked increase in leukostasis of both myeloid leukocytes and lymphocytes was observed following IR. Mino treatment significantly reduced retinal leukocyte numbers following IR and was particularly effective in decreasing the appearance of MHCII+ inflammatory leukocytes. Surprisingly, Mino did not significantly inhibit retinal cell death in this model. Conclusions IR induces a retinal neuroinflammation within hours of reperfusion characterized by inflammatory gene expression, leukocyte adhesion and invasion, and vascular permeability. Despite Mino significantly inhibiting these responses, it failed to block neurodegeneration. PMID:24325836

2013-01-01

51

Evidence of a role for TRPC channels in VEGF-mediated increased vascular permeability in vivo.  

PubMed

Vascular endothelial growth factor (VEGF) increases vascular permeability by stimulating endothelial Ca(2+) influx. Here we provide evidence that links VEGF-mediated increased permeability and endothelial intracellular Ca(2+) concentration ([Ca(2+)](i)) with diacylglycerol (DAG)-mediated activation of the transient receptor potential channels (TRPCs). We used the Landis-Michel technique to measure changes in hydraulic conductivity (L(p)) and fluorescence photometry to quantify changes in endothelial [Ca(2+)](i) in individually perfused Rana mesenteric microvessels in vivo and transfected nonendothelial cells in vitro. The membrane-permeant DAG analog 1-oleoyl-2-acetyl-sn-glycerol (OAG, 100 microM), which is known to increase Ca(2+) influx through TRPCs, transiently increased L(p) 3.8 +/- 1.2-fold (from 1.6 +/- 0.8 to 9.8 +/- 2.7 x 10(-7) cm.s(-1).cmH(2)O(-1); P < 0.0001; n = 18). Protein kinase C inhibition by bisindolylmaleimide (1 microM) did not affect the OAG-induced increases in L(p). OAG also significantly increased microvascular endothelial [Ca(2+)](i) in vivo (n = 13; P < 0.0001), which again was not sensitive to protein kinase C inhibition. VEGF induced a transient increase in endothelial [Ca(2+)](i) in human embryonic kidney cells (HEK-293) that were cotransfected with VEGF receptor 2 and TRPC-6 but not with control, VEGF receptor 2, or TRPC-6 expression vector alone (P < 0.01; n = 9). Flufenamic acid, which has been shown to enhance activity of TRPC-6 but inhibit TRPC-3 and -7, enhanced the VEGF-mediated increase in L(p) in approximately half of the vessels tested but inhibited the response in the other half of the vessels. These data provide evidence consistent with the hypothesis that VEGF increases vascular permeability via DAG-mediated Ca(2+) entry through TRPCs. Although the exact identities of the TRPCs remain to be confirmed, TRPC-6 appears to be a likely candidate in approximately half of the vessels. PMID:14551041

Pocock, T M; Foster, R R; Bates, D O

2004-03-01

52

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

53

Comparison of sodium and urea as indicators of pulmonary vascular permeability.  

PubMed

The objective of this work was to compare the blood-tissue transport properties of 14C-urea and 24Na in the lung circulation. The extraction of both substances was measured relative to intravascular reference tracers (125I-albumin for 24Na, 51Cr red cells and 125I-albumin for 14C-urea) in single-pass transpulmonary multiple indicator curves measured in awake sheep. Sheep were studied in baseline condition, after infusion of histamine solution (4 micrograms/kg-min for 4 hr), and after microvascular pressure was elevated. Permeability-surface area was computed for both sodium (PSn) and urea (PSu) by the Crone extraction model and by a mathematical model. In spite of the fact that the free diffusion coefficients of sodium and urea are approximately equal, the mean ratio of Crone PSn/PSu for baseline studies was 0.76. PSu was significantly increased by histamine infusion but PSn was not. The variation in PSn with histamine and increased pressure was marked. Thus, neither manipulation altered the ratio PSn/PSu in a consistent fashion. Correction of PS for extravascular distribution volumes of urea and Na did not change the PS ratio significantly. We concluded that the diffusional resistance to sodium is higher than expected from its diffusivity, possibly because of charge, and that PS for urea is more sensitive to changes in lung vascular permeability. PMID:6341042

Peterson, B T; Harris, T R; Brigham, K L

1983-02-01

54

Enhanced vascular permeability in rat skin induced by sensory nerve stimulation: Evaluation of the time course and appropriate stimulation parameters  

Microsoft Academic Search

Activation of nociceptors causes them to secrete neuropeptides. The binding of these peptides to receptors on blood vessels causes vasodilation and increased vascular permeability that allows loss of proteins and fluid (plasma extravasation, PE); this contributes to inflammation. This study defines the relationship between electrical activation of nociceptors and PE and evaluates the time course of this response in the

N. M. E. Carmichael; J. O. Dostrovsky; M. P. Charlton

2008-01-01

55

PEDF Improves Cardiac Function in Rats with Acute Myocardial Infarction via Inhibiting Vascular Permeability and Cardiomyocyte Apoptosis.  

PubMed

Pigment epithelium-derived factor (PEDF) is a pleiotropic gene with anti-inflammatory, antioxidant and anti-angiogenic properties. However, recent reports about the effects of PEDF on cardiomyocytes are controversial, and it is not known whether and how PEDF acts to inhibit hypoxic or ischemic endothelial injury in the heart. In the present study, adult Sprague-Dawley rat models of acute myocardial infarction (AMI) were surgically established. PEDF-small interfering RNA (siRNA)-lentivirus (PEDF-RNAi-LV) or PEDF-LV was delivered into the myocardium along the infarct border to knockdown or overexpress PEDF, respectively. Vascular permeability, cardiomyocyte apoptosis, myocardial infarct size and animal cardiac function were analyzed. We also evaluated PEDF's effect on the suppression of the endothelial permeability and cardiomyocyte apoptosis under hypoxia in vitro. The results indicated that PEDF significantly suppressed the vascular permeability and inhibited hypoxia-induced endothelial permeability through PPAR?-dependent tight junction (TJ) production. PEDF protected cardiomyocytes against ischemia or hypoxia-induced cell apoptosis both in vivo and in vitro via preventing the activation of caspase-3. We also found that PEDF significantly reduced myocardial infarct size and enhanced cardiac function in rats with AMI. These data suggest that PEDF could protect cardiac function from ischemic injury, at least by means of reducing vascular permeability, cardiomyocyte apoptosis and myocardial infarct size. PMID:25768344

Zhang, Hao; Wang, Zheng; Feng, Shou-Jie; Xu, Lei; Shi, He-Xian; Chen, Li-Li; Yuan, Guang-Da; Yan, Wei; Zhuang, Wei; Zhang, Yi-Qian; Zhang, Zhong-Ming; Dong, Hong-Yan

2015-01-01

56

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

57

Cardio-ankle vascular index and subclinical heart disease.  

PubMed

The relationship between arterial stiffness, measured as pulse wave velocity (PWV), and the left ventricle is confounded by the effects of blood pressure. We evaluated the relationship between carotid-femoral PWV and cardio-ankle vascular index (CAVI), a less pressure-dependent measurement of the stiffness constant (?) of the aorta and the iliac, femoral and tibial arteries, and obtained prognostically relevant measurements of left ventricular structure and systolic function. CAVI, carotid-femoral PWV and echocardiographic left ventricular mass and systolic function were determined in 133 subjects with either hypertension or high-normal blood pressure (33% treated; 56 ± 16 years, blood pressure 145/89 ± 21/12 mm Hg). Carotid-femoral PWV exhibited a direct relationship with systolic and diastolic blood pressure (r = 0.33/0.26, P < 0.001/0.014), whereas CAVI demonstrated no such relationship (r = 0.12/-0.05, both P > 0.1). Both CAVI and PWV correlated significantly with left ventricular mass index (r = 0.31, P<0.001; r = 0.21, P = 0.014). Subjects with inappropriately high left ventricular masses for a given cardiac workload (n = 44) had higher CAVI values (9.1 ± 2.0 vs. 7.9 ± 1.6, P < 0.001), but not higher PWV values (8.5 ± 2.5 vs. 8.7 ± 2.4, P>0.1). In a multivariate regression model, CAVI was independently associated with inappropriate left ventricular mass (? = 0.40, P < 0.001), along with body mass index. CAVI also demonstrated a negative relationship with left ventricular midwall fractional shortening (r = -0.41, P = 0.001) that was independent of age, sex, blood pressure and left ventricular mass in a multivariate analysis. In conclusion, a high CAVI is associated with inappropriately high left ventricular mass and low midwall systolic function. As a marker of arterial diastolic-to-systolic stiffening, CAVI may have a relationship with left ventricular structure and function that is independent of blood pressure levels. PMID:25231254

Schillaci, Giuseppe; Battista, Francesca; Settimi, Laura; Anastasio, Fabio; Pucci, Giacomo

2015-01-01

58

Effect of Melilotus suaveolens extract on pulmonary microvascular permeability by downregulating vascular endothelial growth factor expression in rats with sepsis  

PubMed Central

A typical indicator of sepsis is the development of progressive subcutaneous and body-cavity edema, which is caused by the breakdown of endothelial barrier function, leading to a marked increase in vascular permeability. Microvascular leakage predisposes to microvascular thrombosis, breakdown of microcirculatory flow and organ failure, which are common events preceding mortality in patients with severe sepsis. Melilotus suaveolens (M. suaveolens) is a Traditional Tibetan Medicine. Previous pharmacological studies have demonstrated that an ethanolic extract of M. suaveolens has powerful anti-inflammatory activity and leads to an improvement in capillary permeability. However, the mechanisms underlying its pharmacological activity remain elusive. The present study aimed to assess the impact of M. suaveolens extract tablets on pulmonary vascular permeability, and their effect on regulating lung inflammation and the expression of vascular endothelial growth factor (VEGF) in the lung tissue of rats with sepsis. A cecal ligation and puncture (CLP) sepsis model was established for both the control and treatment groups. ~2 h prior to surgery, 25 mg/kg of M. suaveolens extract tablet was administered to the treatment group. Polymerase chain reaction and western blot analyses were used to assess the expression of nuclear factor (NF)-?B and VEGF in the lung tissue, and ELISA was applied to detect changes in serum tumor necrosis factor-? as well as interleukins (IL) -1, -4, -6, and -10. The lung permeability, wet/dry weight ratio and lung pathology were determined. The results demonstrated that in the lung tissue of CLP-rats with sepsis, M. suaveolens extract inhibited the expression of NF-?B, reduced the inflammatory response and blocked the expression of VEGF, and thus significantly decreased lung microvascular permeability. The effects of M. Suaveolens extract may be of potential use in the treatment of CLP-mediated lung microvascular permeability. PMID:25571852

LIU, MING-WEI; SU, MEI-XIAN; ZHANG, WEI; WANG, YUN HUI; QIN, LAN-FANG; LIU, XU; TIAN, MAO-LI; QIAN, CHUAN-YUN

2015-01-01

59

Effect of Melilotus suaveolens extract on pulmonary microvascular permeability by downregulating vascular endothelial growth factor expression in rats with sepsis.  

PubMed

A typical indicator of sepsis is the development of progressive subcutaneous and body?cavity edema, which is caused by the breakdown of endothelial barrier function, leading to a marked increase in vascular permeability. Microvascular leakage predisposes to microvascular thrombosis, breakdown of microcirculatory flow and organ failure, which are common events preceding mortality in patients with severe sepsis. Melilotus suaveolens (M. suaveolens) is a Traditional Tibetan Medicine. Previous pharmacological studies have demonstrated that an ethanolic extract of M. suaveolens has powerful anti?inflammatory activity and leads to an improvement in capillary permeability. However, the mechanisms underlying its pharmacological activity remain elusive. The present study aimed to assess the impact of M. suaveolens extract tablets on pulmonary vascular permeability, and their effect on regulating lung inflammation and the expression of vascular endothelial growth factor (VEGF) in the lung tissue of rats with sepsis. A cecal ligation and puncture (CLP) sepsis model was established for both the control and treatment groups. ~2 h prior to surgery, 25 mg/kg of M. suaveolens extract tablet was administered to the treatment group. Polymerase chain reaction and western blot analyses were used to assess the expression of nuclear factor (NF)??B and VEGF in the lung tissue, and ELISA was applied to detect changes in serum tumor necrosis factor?? as well as interleukins (IL) ?1, ?4, ?6, and ?10. The lung permeability, wet/dry weight ratio and lung pathology were determined. The results demonstrated that in the lung tissue of CLP?rats with sepsis, M. suaveolens extract inhibited the expression of NF??B, reduced the inflammatory response and blocked the expression of VEGF, and thus significantly decreased lung microvascular permeability. The effects of M. Suaveolens extract may be of potential use in the treatment of CLP?mediated lung microvascular permeability. PMID:25571852

Liu, Ming-Wei; Su, Mei-Xian; Zhang, Wei; Wang, Yun Hui; Qin, Lan-Fang; Liu, Xu; Tian, Mao-Li; Qian, Chuan-Yun

2015-05-01

60

Effects of thromboxane A 2 analogue on vascular resistance distribution and permeability in isolated blood-perfused dog lungs  

Microsoft Academic Search

This study was designed to determine the effects of thromboxane A2 (TxA2) on the distribution of vascular resistance, lung weight, and microvascular permeability in isolated dog lungs perfused at a constant pressure with autologous blood. The stable TxA2 analogue (STA2; 30 µg, n = 5) caused an increase in pulmonary capillary pressure (Pc) assessed as double-occlusion pressure to 14.0 ±

T. Shibamoto; H.-G. Wang; Y. Yamaguchi; T. Hayashi; Y. Saeki; S. Tanaka; S. Koyama

1995-01-01

61

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.

62

Tumor Necrosis Factor-? induces increased lung vascular permeability: a role for GSK3?/?  

PubMed Central

We tested the hypothesis that glycogen synthase kinase 3?/? (GSK3?/?) modulates tumor necrosis factor-a (TNF) induced increased lung vascular permeability. Rats were treated with TNF (i.v., ~100 ng/ml) or vehicle 0.5 h, 4.0 h and 24.0 h prior to lung isolation. Rats were co-treated with the GSK3?/? inhibitors SB216763 (0.6 mg/kg) or TDZD-8 (1.0 mg/kg). After TNF, the isolated lung was assessed for hemodynamics, wet-dry/dry weight (W-D/D) and extravascular albumin. Extravascular albumin significantly increased at TNF-24 h compared to Control. In the GSK3?/?-inhibited +TNF groups, extravascular albumin was similar to the Control and respective SB216763 and TDZD-8 groups. In separate studies, to assess GSK3?/?-activity, lung lysate was assessed for phospho-GSK3?/?-Ser21/9, total GSK3?/?, un-phospho-?-catenin-Ser33/37and total ?-catenin. In the TNF-4.0 h group, there was no change in GSK3?/phospho-GSK3?-Ser21 but there was an increase in GSK3?/GSK3?-Ser9 compared to Control, indicating GSK3? activation at TNF-4.0 h. GSK3? activation was verified because there was a decrease in un-phospho-?-catenin-Ser33/37/?-catenin in the TNF- 4.0 group, a specific outcome for GSK3? activation. In the SB216763+TNF group, un-phospho-?-catenin-Ser33/37 was similar to Control, indicating prevention of TNF-induced GSK3? activation. In the TNF-24 h group, there were increases in the biomarkers of inflammation phospho-eNOS-Ser 1117 and oxidized protein, which did not occur in the SB216763+TNF-24 h and TDZD-8+TNF-24 h groups. In the SB216763+TNF-24 h and TDZD-8+TNF-24 h groups, un-phospho-?-catenin-Ser33/37 was greater than in the Control, indicating continued inhibition of GSK3?. The data indicates that pharmacologic inhibition of GSK3? inhibits TNF induced increased endothelial permeability associated with lung inflammation. PMID:21316358

Barton-Pai, Amy; Feleder, Carlos; Johnson, Arnold

2011-01-01

63

Physiological levels of A-, B- and C-type natriuretic peptide shed the endothelial glycocalyx and enhance vascular permeability.  

PubMed

Atrial natriuretic peptide (ANP) is a peptide hormone released from the cardiac atria during hypervolemia. Though named for its well-known renal effect, ANP has been demonstrated to acutely increase vascular permeability in vivo. Experimentally, this phenomenon was associated with a marked shedding of the endothelial glycocalyx, at least for supraphysiological intravascular concentrations. This study investigates the impact and mechanism of action of physiological doses of ANP and related peptides on the vascular barrier. In isolated guinea pig hearts, prepared and perfused in a modified Langendorff mode with and without the intravascular presence of the colloid hydroxyethyl starch (HES), we measured functional changes in vascular permeability and glycocalyx shedding related to intracoronary infusion of physiological concentrations of A-, B- and C-type natriuretic peptide (ANP, BNP and CNP). Significant coronary venous washout of glycocalyx constituents (syndecan-1 and heparan sulfate) was observed. As tested for ANP, this effect was positively related to the intracoronary concentration. Intravascular shedding of the glycocalyx was morphologically confirmed by electron microscopy. Also, functional vascular barrier competence decreased, as indicated by significant increases in transudate formation and HES extravasation. Ortho-phenanthroline, a non-specific inhibitor of matrix metalloproteases, was able to reduce ANP-induced glycocalyx shedding. These findings suggest participation of natriuretic peptides in pathophysiological processes like heart failure, inflammation or sepsis. Inhibition of metalloproteases might serve as a basis for future therapeutical options. PMID:23563917

Jacob, Matthias; Saller, Thomas; Chappell, Daniel; Rehm, Markus; Welsch, Ulrich; Becker, Bernhard F

2013-05-01

64

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

65

The Induction of Vascular Endothelial Growth Factor by Ultrafine Carbon Black Contributes to the Increase of Alveolar-Capillary Permeability  

PubMed Central

Ultrafine carbon black (ufCB) can cause proinflammatory response and increase alveolar-capillary permeability. However, the mechanism underlying the increased permeability is not well characterized. Vascular endothelial growth factor (VEGF) is originally recognized as a vascular permeability factor. Oxidative stress generated by hydrogen peroxide (H2O2) stimulates VEGF gene expression. The purpose of this study was to explore the role of VEGF in ufCB-induced alveolar-capillary permeability. Intratracheal instillation of 200 ?g ufCB in mice caused a significant and sustained increase of total proteins in bronchoalveolar lavage (BAL) fluid, with the maximal increase at 21 hr postinstillation. The influx of neutrophils did not significantly increase until 16 hr. It reached the highest level at 21 hr and returned to the basal level by 42 hr. Tumor necrosis factor-? was significantly elevated only at 4 hr. ufCB induced significant increases of VEGF in BAL fluid throughout the study period, with the peak increase at 16 hr. The nonsecreted isoform VEGF188 was not altered after 16 hr of exposure to ufCB. Moreover, there was a strong correlation between VEGF and total proteins in BAL fluid (R2 = 0.7352, p < 0.01). In vivo study supported the role of reactive oxygen species (ROSs) in ufCB-induced VEGF release and protein leakage. The involvement of ROSs was strengthened by the fact that interventions with N-acetyl-cysteine prevented ufCB-induced generation of ROSs and VEGF in vitro. Our study for the first time demonstrates that ufCB induces the production of VEGF, which is associated with the increase of alveolar-capillary permeability. The induction of VEGF by ufCB acts through an ROS-dependent pathway. PMID:15811836

Chang, Chih-Ching; Chiu, Hui-Fen; Wu, Yih-Shyuan; Li, Yi-Chih; Tsai, Mei-Ling; Shen, Chen-Kuo; Yang, Chun-Yuh

2005-01-01

66

Interleukin?1? increases permeability and upregulates the expression of vascular endothelial?cadherin in human renal glomerular endothelial cells.  

PubMed

The renal glomerular capillary endothelium is part of the glomerular filtration barrier and is involved in acute and chronic inflammation of the glomerulus. Glomerular endothelial cells are a unique type of microvascular cell, which remain to be fully characterized. The aim of the present study was to examine the permeability of glomerular endothelial cells and their responses to interleukin (IL)?1?, a pro?inflammatory cytokine. Human glomerular endothelial cell (HRGEC) and human umbilical vein endothelial cell (HUVEC) monolayers were examined using a Transwell permeability assay, transendothelial electrical resistance (TEER) and by determining the expression of the adhesion molecule, vascular endothelial (VE)?cadherin, in the absence or presence of 10 ng/ml IL?1?. Compared with the HUVECs, the HRGECs demonstrated higher permeability, lower TEER and reduced expression of VE?cadherin. IL?1? induced an increase in the permeability and a decrease in the TEER of the HRGECs, however, to a lesser extent compared with the HUVECs. Following IL?1? treatment, the expression of VE?cadherin was increased in the HRGECs and decreased in the HUVECs. These results suggested that HRGECs have distinct biological properties and specific gene expression features in response to IL?1?. PMID:25572875

Du, Linna; Dong, Fengyun; Guo, Ling; Hou, Yinglong; Yi, Fan; Liu, Ju; Xu, Dongmei

2015-05-01

67

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. Östlingc , 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.

68

The ankle—brachial index as a predictor of survival in patients with peripheral vascular disease  

Microsoft Academic Search

Objective: To determine whether the ankle—brachial index (ABI) predicts survival rates among patients with peripheral vascular disease.\\u000a \\u000a \\u000a Design: A retrospective survival analysis of patients with abnormal ABIs who visited the authors’ blood-flow laboratory during 1987.\\u000a The National Death Index was used to ascertain survival status for all patients up to January 1, 1992. Kaplan-Meier and Cox\\u000a proportional hazards analyses were

Mary McGrae McDermott; Joe Feinglass; Rael Slavensky; William H. Pearce

1994-01-01

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

Src inhibitor reduces permeability without disturbing vascularization and prevents bone destruction in steroid-associated osteonecrotic lesions in rabbits  

PubMed Central

To examine the therapeutic effect of Src inhibitor on the VEGF mediating vascular hyperpermeability and bone destruction within steroid-associated osteonecrotic lesions in rabbits. Rabbits with high risk for progress to destructive repair in steroid-associated osteonecrosis were selected according to our published protocol. The selected rabbits were systemically administrated with either Anti-VEGF antibody (Anti-VEGF Group) or Src inhibitor (Src-Inhibition Group) or VEGF (VEGF-Supplement Group) or a combination of VEGF and Src inhibitor (Supplement & Inhibition Group) or control vehicle (Control Group) for 4 weeks. At 0, 2 and 4 weeks after administration, in vivo dynamic MRI, micro-CT based-angiography, histomorphometry and immunoblotting were employed to evaluate the vascular and skeletal events in different groups. The incidence of the destructive repair in the Anti-VEGF Group, Src-Inhibition Group and Supplement & Inhibition Group was all significantly lower than that in the Control Group. The angiogenesis was promoted in VEGF-Supplement Group, Src-Inhibition Group and Supplement & Inhibition Group, while the hyperpermeability was inhibited in Anti-VEGF Group, Src-Inhibition Group and Supplement & Inhibition Group. The trabecular structure was improved in Src-Inhibition Group and Supplement & Inhibition Group. Src inhibitor could reduce permeability without disturbing vascularization and prevent destructive repair in steroid-associated osteonecrosis. PMID:25748225

He, Yi-Xin; Liu, Jin; Guo, Baosheng; Wang, Yi-Xiang; Pan, Xiaohua; Li, Defang; Tang, Tao; Chen, Yang; Peng, Songlin; Bian, Zhaoxiang; Liang, Zicai; Zhang, Bao-Ting; Lu, Aiping; Zhang, Ge

2015-01-01

71

Src inhibitor reduces permeability without disturbing vascularization and prevents bone destruction in steroid-associated osteonecrotic lesions in rabbits.  

PubMed

To examine the therapeutic effect of Src inhibitor on the VEGF mediating vascular hyperpermeability and bone destruction within steroid-associated osteonecrotic lesions in rabbits. Rabbits with high risk for progress to destructive repair in steroid-associated osteonecrosis were selected according to our published protocol. The selected rabbits were systemically administrated with either Anti-VEGF antibody (Anti-VEGF Group) or Src inhibitor (Src-Inhibition Group) or VEGF (VEGF-Supplement Group) or a combination of VEGF and Src inhibitor (Supplement &Inhibition Group) or control vehicle (Control Group) for 4 weeks. At 0, 2 and 4 weeks after administration, in vivo dynamic MRI, micro-CT based-angiography, histomorphometry and immunoblotting were employed to evaluate the vascular and skeletal events in different groups. The incidence of the destructive repair in the Anti-VEGF Group, Src-Inhibition Group and Supplement &Inhibition Group was all significantly lower than that in the Control Group. The angiogenesis was promoted in VEGF-Supplement Group, Src-Inhibition Group and Supplement &Inhibition Group, while the hyperpermeability was inhibited in Anti-VEGF Group, Src-Inhibition Group and Supplement &Inhibition Group. The trabecular structure was improved in Src-Inhibition Group and Supplement &Inhibition Group. Src inhibitor could reduce permeability without disturbing vascularization and prevent destructive repair in steroid-associated osteonecrosis. PMID:25748225

He, Yi-Xin; Liu, Jin; Guo, Baosheng; Wang, Yi-Xiang; Pan, Xiaohua; Li, Defang; Tang, Tao; Chen, Yang; Peng, Songlin; Bian, Zhaoxiang; Liang, Zicai; Zhang, Bao-Ting; Lu, Aiping; Zhang, Ge

2015-01-01

72

Osmotic water permeability of capillaries from the isolated spiral ligament: new in-vitro techniques for the study of vascular permeability and diameter.  

PubMed

Perilymph is separated from blood by a barrier called the blood-labyrinth or blood-perilymph barrier in analogy to the blood-brain or blood-cerebrospinal fluid barrier. These barriers consist mainly of vascular endothelial cells. To characterize the blood-labyrinth barrier we developed in vitro techniques for the quantitative determination of the osmotic water permeability and for the determination of changes in the diameter of isolated inner ear capillaries. Both techniques rely on measurement of the velocity of marker red cells trapped in the lumen of capillaries. The velocity of marker red cells is a measure for the capillary permeability when a water flux across the capillary wall is induced by an osmotic gradient or a measure for a change in the capillary diameter. With these techniques the osmotic water permeability coefficient (Pf) and the pH sensitivity of isolated capillaries from the spiral ligament of the inner ear was determined. Pf at 23 degrees C was (1.49 +/- 0.17) 10(-3) cm/s at pH 7.4 and (1.61 +/- 0.23) 10(-3) cm/s at pH 6.8 (n = 12: mean +/- SEM: n = number of tissues). Pf at 37 degrees C was (2.26 +/- 0.23) 10(-3) cm/s at pH 7.4 and (2.35 +/- 0.17) 10(-3) cm/s at pH 6.8 (n = 13). No change in capillary diameter was observed when the pH of the interstitial fluid was lowered from pH 7.4 to 6.8. These data demonstrate that Pf and the capillary diameter of spiral ligament capillaries are pH independent and suggest that water crosses the blood-labyrinth barrier via an aqueous pathway. Further, these data suggest that the relatively low Pf is another characteristic shared by the blood-labyrinth and the blood-brain barrier. PMID:8793507

Wangemann, P; Liu, J

1996-05-01

73

Production of C2 toxin by Clostridium botulinum types C and D as determined by its vascular permeability activity.  

PubMed Central

Vascular permeability (VP) activity was demonstrated by intradermal injection of culture supernatants of Clostridium botulinum types C and D and strains producing only C2 toxin. The activity was enhanced markedly by treatment with trypsin. It was abolished by antiserum against C2 toxin and by antisera specific for components I and II of C2 toxin, but not by anti-type C or -type D neurotoxin serum. Of 14 strains examined, 10 had VP activity. No VP activity was demonstrated in the culture supernatants of C. botulinum type A, B, E, or F. These results indicate that VP activity is a function of the C2 toxin elaborated by C. botulinum types C and D and that the toxin possesses VP as well as lethal activities. These findings raise the possibility that VP activity of C2 toxin exerts synergic effect(s) with neurotoxin in the pathogenesis of botulism caused by type C and D strains. PMID:7033132

Ohishi, I; Sakaguchi, G

1982-01-01

74

Mechanotransduction by GEF-H1 as a novel mechanism of ventilator-induced vascular endothelial permeability  

PubMed Central

Pathological lung overdistention associated with mechanical ventilation at high tidal volumes (ventilator-induced lung injury; VILI) compromises endothelial cell (EC) barrier leading to development of pulmonary edema and increased morbidity and mortality. We have previously shown involvement of microtubule (MT)-associated Rho-specific guanine nucleotide exchange factor GEF-H1 in the agonist-induced regulation of EC permeability. Using an in vitro model of human pulmonary EC exposed to VILI-relevant magnitude of cyclic stretch (18% CS) we tested a hypothesis that CS-induced alterations in MT dynamics contribute to the activation of Rho-dependent signaling via GEF-H1 and mediate early EC response to pathological mechanical stretch. Acute CS (30 min) induced disassembly of MT network, cell reorientation, and activation of Rho pathway, which was prevented by MT stabilizer taxol. siRNA-based GEF-H1 knockdown suppressed CS-induced disassembly of MT network, abolished Rho signaling, and attenuated CS-induced stress fiber formation and EC realignment compared with nonspecific RNA controls. Depletion of GEF-H1 in the murine two-hit model of VILI attenuated vascular leak induced by lung ventilation at high tidal volume and thrombin-derived peptide TRAP6. These data show for the first time the critical involvement of microtubules and microtubule-associated GEF-H1 in lung vascular endothelial barrier dysfunction induced by pathological mechanical strain. PMID:20348280

Fu, Panfeng; Xing, Junjie; Yakubov, Bakhtiyor; Cokic, Ivan; Birukov, Konstantin G.

2010-01-01

75

The genesis of peritumoral vasogenic brain edema and tumor cysts: a hypothetical role for tumor-derived vascular permeability factor.  

PubMed Central

Cerebral edema and fluid-filled cysts are common accompaniments of brain tumors. They contribute to the mass effect imposed by the primary tumor and are often responsible for a patient's signs and symptoms. Cerebral edema significantly increases the morbidity associated with tumor biopsy, excision, radiation therapy, and chemotherapy. Both edema and cyst formation are thought to result from a deficiency in the blood-brain barrier, with consequent extravasation of water, electrolytes, and plasma proteins from altered tumor microvessels. The resultant expansion of the cerebral interstitial space contributes to the elevated intracranial pressure observed with brain tumors. Departure from the typical blood-brain barrier microvascular architecture may only partially explain the occurrence of edema and tumor cyst formation. Biochemical mediators have also been implicated in vascular extravasation. Vascular permeability factor or vascular endothelial growth factor (VPF/VEGF) is a protein that has recently been isolated from a variety of tumors including human brain tumors. VPFb is an extraordinarily potent inducer of both microvascular extravasation (edemagenesis) and the formation of new blood vessels (angiogenesis). Its role in tumor growth and progression would therefore appear pivotal. Herein, the author presents an updated account of the investigation of VPF. Historical and clinical perspectives of the study and treatment of tumor associated edema are provided. The efficacy of high-dose dexamethasone in the treatment of neoplastic brain edema is discussed. A hypothetical role for VPF in edemagenesis is presented and discussed. It is hoped that an expanded understanding of the mechanisms responsible for the genesis of edema will ultimately facilitate therapeutic intervention. Images Figure 1 Figure 2 Figure 3 PMID:7516104

Criscuolo, G. R.

1993-01-01

76

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

SciTech Connect

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

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

1991-07-15

77

An Age Index for Vascular System Based on Photoplethysmogram Pulse Contour Analysis  

Microsoft Academic Search

An approach based pulse on contour analysis is proposed for the development of an aging index for the vascular system. The\\u000a approach is non-invasive, using photoplethysmography (PPG), which is in wide clinical use. A probe is applied to the subject’s\\u000a finger-tip to provide a measure of the pulse waveform. The measured waveforms are filtered, digitized and post-processed.\\u000a Individual pulses are

Kalaivani Chellappan; M. A. Mohd Ali; E. Zahedi

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

Minimally invasive molecular delivery into the brain using optical modulation of vascular permeability  

PubMed Central

Systemic delivery of bioactive molecules in the CNS is hampered by the blood–brain barrier, which has bottlenecked noninvasive physiological study of the brain and the development of CNS drugs. Here we report that irradiation with an ultrashort pulsed laser to the blood vessel wall induces transient leakage of blood plasma without compromising vascular integrity. By combining this method with a systemic injection, we delivered target molecules in various tissues, including the brain cortex. This tool allows minimally invasive local delivery of chemical probes, nanoparticles, and viral vectors into the brain cortex. Furthermore, we demonstrated astrocyte-mediated vasodilation in vivo without opening the skull, using this method to load a calcium indicator in conjunction with label-free photoactivation of astrocytes. PMID:21576460

Choi, Myunghwan; Ku, Taeyun; Chong, Kyuha; Yoon, Jonghee; Choi, Chulhee

2011-01-01

80

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

PubMed

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

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

1994-02-28

81

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

PubMed Central

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

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

2011-01-01

82

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

83

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

PubMed Central

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

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

2013-01-01

84

Ozone-induced bronchial hyperresponsiveness in the rat is not accompanied by neutrophil influx or increased vascular permeability in the trachea  

SciTech Connect

We determined whether ozone-induced bronchial hyperresponsiveness in the rat is accompanied by neutrophil influx or increased vascular permeability in the trachea. Three groups of female Long-Evans rats were studied. One group was exposed to 4 ppm ozone for 2 h and studied immediately thereafter, another group was similarly exposed but was not studied until 24 h after the ozone exposure, and a third group consisted of control rats that breathed room air. Increases in total pulmonary resistance caused by acetylcholine aerosol were measured to assess bronchial responsiveness in these 3 groups. In parallel studies, neutrophil influx into the tracheal mucosa was quantified by counting cells within whole mounts of tracheas that were treated histochemically to stain the myeloperoxidase in neutrophils, and tracheal vascular permeability was quantified by measuring the amount of Evans blue dye extravasated into the trachea. In the rats studied immediately after the ozone exposure, the concentration of acetylcholine required to increase total pulmonary resistance to three-fold the baseline value was only 6% of that required in the controls. In the rats studied 24 h after the ozone exposure, this provocative acetylcholine concentration was not significantly different from that of the controls. Neither the number of neutrophils in the tracheal mucosa nor the amount of Evans blue dye extravasated into the trachea was significantly different from the corresponding control values at either time. We conclude that rats exposed to ozone develop bronchial hyperresponsiveness without detectable neutrophil influx or increased vascular permeability in the trachea.

Evans, T.W.; Brokaw, J.J.; Chung, K.F.; Nadel, J.A.; McDonald, D.M.

1988-07-01

85

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

86

Lignans from the stems and leaves of Brandisia hancei and their effects on VEGF-induced vascular permeability and migration of HRECs and DLAV formation in zebrafish.  

PubMed

In our continuing search for novel antiangiogenic agents, a new lignan glycoside, (7R,8R)-1-(4-O-?-d-glucopyranosyl-3-methoxyphenyl)-2-{2-methoxy-4-[1-(E)-propene-3-ol]-phenoxyl}-propane-1,3-diol (1), along with three known lignans (2-4), were isolated from the 80% EtOH extract of Brandisia hancei stems and leaves. These isolates (1-4) were subjected to an in vitro bioassay to evaluate their effects on vascular endothelial growth factor (VEGF)-induced vascular permeability and migration of human retinal endothelial cells (HRECs). Of the compounds tested, compound 1 resulted in the greatest reduction in VEGF-induced vascular permeability by about 31.5% at 10 ?M compared to the VEGF-treated control. In the migration assay, compounds 1 and 2 significantly decreased VEGF-induced HREC migration. Furthermore, zebrafish embryos treated with compounds 1 and 2 showed mild reductions of dorsal longitudinal anastomotic vessel (DLAV) formation. PMID:25495132

Lee, Ik-Soo; Kim, Young Sook; Jung, Seung-Hyun; Yu, Song Yi; Kim, Joo-Hwan; Sun, Hang; Kim, Jin Sook

2015-04-01

87

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

88

Characterization of cutaneous vascular permeability induced by platelet-activating factor in guinea pigs and rats and its inhibition by a platelet-activating factor receptor antagonist  

SciTech Connect

Mechanisms of platelet-activating factor (PAF)-induced increases of cutaneous vascular permeability in guinea pigs and in rats were further explored. PAF so far is the most potent vasoactive mediator, being more than 1000-fold more potent than histamine and bradykinin in both species. In guinea pigs, there is a time delay of 5 to 10 minutes before PAF action, whereas, in the rat, the increased vasopermeability occurs immediately following the intradermal PAF injection. Relative vasoactive potencies of PAF and several structure-related analogues in both species correlate very well with their relative inhibition of the binding of /sup 3/H-PAF to specific receptor sites on isolated rabbit platelet plasma membranes and their aggregatory abilities of rabbit platelets. Furthermore, the PAF-induced cutaneous vascular permeability is inhibitable by a competitive specific PAF receptor antagonist, kadsurenone, suggesting that binding of PAF to its specific receptor site is the first step to initiate its action of increased cutaneous vascular permeability. Several pure cyclooxygenase inhibitors, including indomethacin, diflunisal, and flurbiprofen, and the dual cyclooxygenase/lipoxygenase inhibitor, BW755C, but not the histamine antagonists, inhibit the PAF-induced vasopermeability in guinea pigs. The inhibition by indomethacin or BW755C can be fully reversed by coinjection intradermally with PAF and prostaglandin E1 but not leukotriene B4. Also, prostaglandin E1 but not leukotriene B4 enhances the guinea pig in vivo response to PAF in this model. However, in rats, none of the cyclooxygenase inhibitors, histamine antagonists, or BW755C inhibit the PAF effect of cutaneous phenomena.

Hwang, S.B.; Li, C.L.; Lam, M.H.; Shen, T.Y.

1985-06-01

89

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

90

Oxidative Stress and Modification of Renal Vascular Permeability Are Associated with Acute Kidney Injury during P. berghei ANKA Infection  

PubMed Central

Malaria associated-acute kidney injury (AKI) is associated with 45% of mortality in adult patients hospitalized with severe form of the disease. However, the causes that lead to a framework of malaria-associated AKI are still poorly characterized. Some clinical studies speculate that oxidative stress products, a characteristic of Plasmodium infection, as well as proinflammatory response induced by the parasite are involved in its pathophysiology. Therefore, we aimed to investigate the development of malaria-associated AKI during infection by P. berghei ANKA, with special attention to the role played by the inflammatory response and the involvement of oxidative stress. For that, we took advantage of an experimental model of severe malaria that showed significant changes in the renal pathophysiology to investigate the role of malaria infection in the renal microvascular permeability and tissue injury. Therefore, BALB/c mice were infected with P. berghei ANKA. To assess renal function, creatinine, blood urea nitrogen, and ratio of proteinuria and creatininuria were evaluated. The products of oxidative stress, as well as cytokine profile were quantified in plasma and renal tissue. The change of renal microvascular permeability, tissue hypoxia and cellular apoptosis were also evaluated. Parasite infection resulted in renal dysfunction. Furthermore, we observed increased expression of adhesion molecule, proinflammatory cytokines and products of oxidative stress, associated with a decrease mRNA expression of HO-1 in kidney tissue of infected mice. The measurement of lipoprotein oxidizability also showed a significant increase in plasma of infected animals. Together, our findings support the idea that products of oxidative stress, as well as the immune response against the parasite are crucial to changes in kidney architecture and microvascular endothelial permeability of BALB/c mice infected with P. berghei ANKA. PMID:22952850

Elias, Rosa Maria; Correa-Costa, Matheus; Barreto, Claudiene Rodrigues; Silva, Reinaldo Correia; Hayashida, Caroline Y.; Castoldi, Ângela; Gonçalves, Giselle Martins; Braga, Tarcio Teodoro; Barboza, Renato; Rios, Francisco José; Keller, Alexandre Castro; Cenedeze, Marcos Antonio; Hyane, Meire Ioshie; D'Império-Lima, Maria Regina; Figueiredo-Neto, Antônio Martins; Reis, Marlene Antônia; Marinho, Cláudio Romero Farias; Pacheco-Silva, Alvaro; Câmara, Niels Olsen Saraiva

2012-01-01

91

Simultaneous optical and mr imaging of tissue within implanted window chamber: System development and application in measuring vascular permeability  

NASA Astrophysics Data System (ADS)

Simultaneous optical imaging and MRI of a dorsal skin-fold window chamber mouse model is investigated as a novel methodology to study the tumor microenvironment. Simultaneous imaging with two modalities allows for cross-validation of results, integration of the capabilities of the two modalities in one study and mitigation of invasive factors, such as surgery and anesthesia, in an in-vivo experiment. To make this investigation possible, three optical imaging systems were developed that operated inside the MRI scanner. One of the developed systems was applied to estimate vascular kinetic parameters of tumors in a dorsal skin-fold window chamber mouse model with simultaneous optical and MRI imaging. The target of imaging was a molecular agent that was dual labeled with both optical and MRI contrast agents. The labeling of the molecular agent, characteristics of the developed optical systems, the methodologies of measuring vascular kinetic parameters using optical imaging and MRI data, and the obtained results are described and illustrated.

Shayegan Salek, Mir Farrokh

92

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

93

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

94

Comparison of iron-59, indium-111, and gallium-69 transferrin as a macromolecular tracer of vascular permeability and the transferrin receptor  

SciTech Connect

Tracer amounts of ({sup 59}Fe++)citrate, ({sup 111}In+++)chloride, and ({sup 68}Ga+++)chloride were complexed with autologous plasma transferrin. Each of these complexes were co-administered with ({sup 125}I)albumin by i.v. injection and their biodistribution was studied in Wistar rats. The plasma clearance of {sup 59}Fe and ({sup 125}I)albumin was monoexponential with half-times of 49-70 and 277 min, respectively. The plasma clearance of {sup 68}Ga and {sup 111}In was biexponential with second component half-times of 157 and 232 min, respectively. Indium-111 tissue distribution was similar to that of ({sup 125}I)albumin in heart, lung, muscle, brain and Walker-256 allograft. Iron-59 distribution spaces were generally the highest of the metal complexes in all tissues except muscle, where the {sup 68}Ga space was highest. The effects of transferrin-specific receptor-mediated endocytosis can be avoided in many organs and Walker-256 allografts by using the indium-transferrin complex, and the radiolabeled complex may be a convenient macromolecular tracer to estimate vascular permeability and vessel pore size in tumor and systemic tissue. In contrast, the iron-transferrin complex may be useful for measuring and imaging transferrin-specific receptors in brain and tumor tissue.

Otsuki, H.; Brunetti, A.; Owens, E.S.; Finn, R.D.; Blasberg, R.G. (National Institutes of Health, Bethesda, MD (USA))

1989-10-01

95

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

96

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

97

Physiological Cost Index and Comfort Walking Speed in Two Level Lower Limb Amputees Having No Vascular Disease  

PubMed Central

Background: The Physiological Cost Index (PCI) was introduced by MacGregor to estimate the energy cost in walking of healthy people, also it has been reported for persons with lower limb amputation, walking with prosthesis. Objective: To assess energy cost and walking speed in two level lower limb amputation: transfemoral and transtibial amputation and to determine if the age and prosthetic walking supported with walking aids have impact on energy cost and walking speed. Methods: A prospective cross sectional study was performed in two level lower limb amputees with no vascular disease who were rehabilitated at the Department of Prosthetics and Orthotics at the University Clinical Center of Kosovo. The Physiological Cost Index (PCI) was assessed by five minutes of continuous indoor walking at Comfort Walking Speed (CWS). Results: Eighty three lower limb amputees were recruited. It is shown relevant impact of level of amputation in PCI (t=6.8, p<0.001) and CWS (T=487, p<0.001). The great influence of using crutches during prosthetic walking in PCI (ANOVA F= 39.5 P < 0.001) and CWS (ANOVA F=32.01, P <0.001) has been shown by One Way ANOVA test. The correlation coefficient (R) showed a significant correlation of age with PCI and CWS in both groups of amputation. Conclusions: Walking with transfemoral prosthesis or using walking aids during prosthetic ambulation is matched with higher cost of energy and slower walking speed. Advanced age was shown with high impact on PCI and CWS in both groups of amputees. PMID:25870485

Vllasolli, Teuta Osmani; Orovcanec, Nikola; Zafirova, Beti; Krasniqi, Blerim; Murtezani, Ardiana; Krasniqi, Valbona; Rama, Bukurije

2015-01-01

98

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

PubMed Central

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

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

2010-01-01

99

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

100

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

NASA Astrophysics Data System (ADS)

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

Hosseini, Mirhasan; Javaherian, Abdolrahim; Movahed, Bahram

2014-10-01

101

Evidence that prolonged histamine suffusions produce transient increases in vascular permeability subsequent to the formation of venular macromolecular leakage sites. Proof of the Majno-Palade hypothesis.  

PubMed Central

The aim of this study was to determine whether histamine-stimulated increases in macromolecular efflux are dependent on the formation of specific vascular leakage sites, or whether other mechanisms need to be invoked to explain the increase in macromolecular efflux produced by this inflammatory mediator. Intravital light microscopy was used to localize and quantitate vascular macromolecular leakage sites in the noneverted hamster cheek pouch. Fluorimetric measurements of plasma and suffusate tracer (FITC-D 70,000 mol wt) concentrations were utilized to quantitate changes in macromolecular efflux. In some experiments, the FITC-D was injected intravenously either at the start of or after the start of a prolonged histamine suffusion for estimation of the duration of the vascular FITC-D leakage response. In saline control cheek pouches there were few, if any, visible FITC-D vascular leakage sites and only small increases in the [FITC-D]s. The arteriolar vasodilators papaverine (1 X 10(-5) M) and isoproterenol (1 X 10(-5) M) failed to increase the formation of vascular FITC-D leakage sites, and the magnitude of the increase in [FITC-D]s produced by these agents was similar to that observed in saline controls. Histamine (1 X 10(-5) M) suffused for either 15, 60, or 120 minutes produced marked increases in [FITC-D]s and in the number of venular FITC-D leakage sites. The venular FITC-D leakage sites began to fade after 10-20 minutes, eventually disappearing altogether. In contrast, the [FITC-D]s was markedly increased throughout the 120-minute observation period. Treatment with papaverine prior to and during the 60-minute histamine suffusion failed to prevent the mediator-stimulated vascular leakage response. In contrast, similar treatment with isoproterenol inhibited the histamine-stimulated increases in [FITC-D]s and the formation of venular FITC-D leakage sites. When the tracer was injected intravenously at the start of the 60-minute histamine suffusion (1 X 10(-5) M), the [FITC-D]s and the number of vascular leakage sites were markedly increased. However, when the tracer was injected intravenously 30 minutes after the start of the 60-minute histamine suffusion, there were only minimal increases in [FITC-D]s and the formation of venular leakage sites. These findings suggest that prolonged suffusions of histamine produce transient increases in macromolecular efflux which are dependent on the formation of discrete venular macromolecular leakage sites.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2424313

Horan, K. L.; Adamski, S. W.; Ayele, W.; Langone, J. J.; Grega, G. J.

1986-01-01

102

A disorder of sympathomimetic amines leading to increased vascular permeability may be the etiologic factor in various treatment refractory health problems in women.  

PubMed

There is an evidence that increased capillary permeability in the standing position is related to a deficit in the sympathetic nervous system. The leakage of this fluid leads to various clinical conditions which frequently puzzle the consulting physician because despite the frequency of this condition intelligent physicians and patients are unaware of the cause of their condition. One of the most common manifestations is the inability to lose weight despite proper dieting. A randomized study comparing the efficacy of a diuretic, a converting enzyme inhibitor, spironolactone and a sympathomimetic amine on weight loss in diet refractory women found that only the latter in the form of dextroamphetamine sulfate demonstrated significant weight reduction over a six month time span. In fact, the dextroamphetamine sulfate proved effective when given in the next 6 months to the three groups failing to respond for the first 6 months. The diagnosis of a deficit in sympathomimetic amines is established by demonstrating an abnormal clearance of a water load in the erect position and exclusion of other conditions that are associated with an abnormal free water clearance, e.g., hypothyroidism, renal or liver disease or congestive heart failure. The original definition of an abnormal water load test was excretion of <55% of a 1500 ml water load in 6h but we found that <75% defines a greater population who suffer from this problem. There are several conditions that have proven refractory to conventional theory that respond quickly and effectively to sympathomimetic amines. There have been many anecdotal reports of relieving interactable pain syndromes quickly and efficiently with sympathomimetic amine theory, despite failure with a multitude of other therapies. These include interstitial cystitis and pelvic pain that was attributed to endometriosis, gastrointestinal pain including esophagitis and gastroparesis, headaches, joint pain, fibromyalgia, and carpal tunnel syndrome. It is not clear if the improvement in pain is related to a decrease in fluid retention or a direct effect of the sympathomimetic amines on the sympathetic nervous system. Sympathomimetic amine theory has helped other conditions besides pain, e.g., chronic fatigue, vasomotor symptoms in young women not associated with decreased ovarian egg reserve, and chronic urticaria resistant to all other therapies. Thus, these studies strongly suggest that physicians be aware of this condition involving a deficit in the sympathetic nervous system when faced with various enigmatic complaints especially if standard therapy has not proven effective. PMID:17765403

Check, J H; Katsoff, D; Kaplan, H; Liss, J; Boimel, P

2008-01-01

103

Vascular hyperpermeability and aging.  

PubMed

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

2014-04-01

104

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

105

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.

106

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,

107

Cardiorespiratory Fitness is a Strong Predictor of the Cardio-ankle Vascular Index in Hypertensive Middle-aged and Elderly Japanese Men.  

PubMed

Aim: This study aimed to examine whether cardiorespiratory fitness (CRF) is associated with arterial stiffening, evaluated using the cardio-ankle vascular index (CAVI), independent of visceral fat (VF) in middle-aged and elderly Japanese men. We also examined whether the relationship between CRF and the CAVI is modified by age and/or hypertension. Methods: The CAVI was determined in 157 Japanese men (age range, 30-79 years), including 96 hypertensive subjects (61.1%). CRF was assessed by measuring the peak oxygen uptake (O2peak). The subjects were divided into low- and high-CRF groups, and the VF area was assessed using magnetic resonance imaging. Results: The O2peak correlated with the CAVI following adjustment for age and body mass index in the middle-aged and elderly groups (all the subjects: r=-0.285, p?0.001; middle-aged: r=-0.240, p=0.040; elderly: r=-0.225, p=0.049). VF also correlated with the CAVI (r=0.230, p=0.004). A multiple linear regression analysis revealed that age (?=0.406, p?0.001) and the O2peak (?=-0.186, p=0.015) were associated with the CAVI independently of VF and the mean blood pressure. Twoway ANCOVA adjusted for age demonstrated that the hypertensive individuals had higher CAVI values than the normotensive individuals in the low-CRF group, whereas no significant differences in the CAVI were observed in the high-CRF group (p for interaction ?0.05). Conclusions: In the present study, CRF was found to be associated with the CAVI, independent of age and VF, in hypertensive middle-aged and elderly Japanese men. PMID:25342380

Tanisawa, Kumpei; Ito, Tomoko; Sun, Xiaomin; Kawakami, Ryoko; Oshima, Satomi; Gando, Yuko; Cao, Zhen-Bo; Sakamoto, Shizuo; Higuchi, Mitsuru

2014-10-22

108

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

109

Neutrophils, nitric oxide, and microvascular permeability in severe sepsis  

Technology Transfer Automated Retrieval System (TEKTRAN)

STUDY OBJECTIVES: Alterations in microvascular permeability are prevalent in patients with sepsis; a recent study reported that patients with septic shock had increased capillary filtration coefficient (Kf), a noninvasive index of microvascular permeability. We aimed to determine whether patients wi...

110

Lack of IL-6 increases blood-brain barrier permeability in fungal meningitis.  

PubMed

The pathogenesis of increased blood-brain barrier permeability during Cryptococcus meningitis is still largely unknown. Interleukin (IL-6) is a multifunctional cytokine, and numerous studies have shown that IL-6 influences the integrity of the blood-brain barrier. In this study we investigated the role of IL-6 in Cryptococcus meningitis. First, wild-type or IL-6-/- mice were injected with Cryptococcus neoformans (C. neoformans) and the survival time in both groups was recorded. Second, the number of fungi was measured in the brains of IL-6-/- wild-type mice. Finally, the blood-brain barrier permeability index was detected in infected IL-6-/- mice treated with recombinant human IL-6. The blood-brain barrier permeability index was measured in infected wild-type mice treated with anti-IL-6 antibodies as well. The survival of IL-6-/- mice injected with C. neoformans was significantly lower than that of identically challenged wild-type mice. The infected IL-6-/- mice had significantly larger brain fungal burdens than wild-type mice. Furthermore, increased blood-brain barrier index was found in infected IL-6-/- mice when compared with that in infected control mice. Similar results were obtained when mice challenged with C. neoformans were treated systemically with neutralizing anti-IL-6 antibodies, resulting in an elevation of vascular permeability. Our data revealed that IL-6 reduced the blood-brain barrier permeability during Cryptococcus meningitis, and it might provide an explanation for the significantly lower survival of infected IL-6-/- mice. PMID:25740137

Li, Xiang; Liu, Guiyang; Ma, Jianli; Zhou, Liang; Zhang, Qingzhe; Gao, Lei

2015-03-01

111

Spatial and Phenotypic Characterization of Vascular Remodeling in a Mouse Model of Asthma  

Microsoft Academic Search

Asthma is a chronic inflammatory disease characterized by airway wall remodeling in which vascular remodeling is thought to be a main contributor. Vascular endothelial growth factor (VEGF) is known as a major regulator of angiogenesis and enhancer of vascular permeability. Here, we define the spatial nature of vascular remodeling and the role of VEGF and its receptors (Flt-1 and Flk-1)

Xinming Su; Namiko Taniuchi; Enjing Jin; Masakazu Fujiwara; Lei Zhang; Mohammad Ghazizadeh; Hiroyuki Tashimo; Naomi Yamashita; Ken Ohta; Oichi Kawanami

2008-01-01

112

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. PMID:25667739

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

2014-01-01

113

Protein kinase C-related kinase and ROCK are required for thrombin-induced endothelial cell permeability downstream from Galpha12/13 and Galpha11/q  

E-print Network

in the vascular barrier permeability, and their implications in aberrant angiogenesis are still much less permeability downstream from Galpha12/13 and Galpha11/q Gavard Julie 1 * , Gutkind J Silvio 1 Department.gavard@inserm.fr> Abstract Increase in vascular permeability occurs under many physiological conditions such as wound repair

Boyer, Edmond

114

Developments in permeable and low permeability barriers  

SciTech Connect

The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a pathway in the ground has enabled a re-thinking of many of the concepts of containment. In particular it offers the potential for the control of the flux from a contaminated area by controlling the contaminant concentration in the pathway(s) as well as or instead of using a low permeability barrier. The paper outlines the basic concepts of the reactive treatment zone and the use of permeable and low permeability reactive systems. The paper then gives a case history of the installation of a permeable barrier using an in-situ reaction chamber.

Jefferis, S.A. [Golder Associates United Kingdom Ltd., Berkshire (United Kingdom); Norris, G.H. [Nortel Ltd., London (United Kingdom); Thomas, A.O. [Golder Associates Geoanalysis s.r.l., Turin (Italy)

1997-12-31

115

Vascular lesions.  

PubMed

Advances in laser and light-based technology have increased their potential applications, safety and efficacy for the management of vascular lesions in dermatology. Light devices for vascular lesions include the variable-pulse 532 nm potassium titanyl phosphate laser, 577 to 595 nm pulsed dye laser, intense pulsed light devices, and 800 to 940 nm diode, long-pulse 755 nm alexandrite and 1,064 nm Nd:YAG lasers. This review will discuss the various different laser and light-based devices, and provide a focused treatment approach for the management of common congenital and acquired vascular lesions. PMID:21865800

Ting, Patricia T; Rao, Jaggi

2011-01-01

116

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...

117

Vascular Cures  

MedlinePLUS

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

118

Endothelial permeability and VE-cadherin  

PubMed Central

The endothelium forms a selective semi-permeable barrier controlling bidirectional transfer between blood vessel and irrigated tissues. This crucial function relies on the dynamic architecture of endothelial cell–cell junctions, and in particular, VE-cadherin-mediated contacts. VE-cadherin indeed chiefly organizes the opening and closing of the endothelial barrier, and is central in permeability changes. In this review, the way VE-cadherin-based contacts are formed and maintained is first presented, including molecular traits of its expression, partners, and signaling. In a second part, the mechanisms by which VE-cadherin adhesion can be disrupted, leading to cell–cell junction weakening and endothelial permeability increase, are described. Overall, the molecular basis for VE-cadherin control of the endothelial barrier function is of high interest for biomedical research, as vascular leakage is observed in many pathological conditions and human diseases. PMID:25422846

Gavard, Julie

2014-01-01

119

Extended correlations of porosity, permeability, and formation resistivity factor  

E-print Network

, and applications are cited including an illustration of the calculation of permeability from well logs. DEDICATION To my wife and daughter, who through their love and support, have contributed immensely to this work. ACKNOWLEDGMENT I would like to express my... versus Permeability Index for an Unknown Number of Sandstone Formations 53 17 Correlation between Gamma Ray and Formati. on Factor 58 18 Comparison between Calculated and Measured Permeabilities for Sample Well ? 1 Using Core Data for Porosity 60...

Ellis, Keith Wade

1987-01-01

120

An in vivo Assay to Test Blood Vessel Permeability  

PubMed Central

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

Radu, Maria; Chernoff, Jonathan

2013-01-01

121

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

122

Vascular Diseases  

MedlinePLUS

... and from the heart. Problems of the vascular system are common and can be serious. Arteries can become thick and stiff, a problem called atherosclerosis. Blood clots can clog vessels and block blood flow to the heart or brain. Weakened blood vessels ...

123

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

124

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

125

Peripheral vascular stiffness, assessed with two-dimensional speckle tracking versus the degree of coronary artery calcification, evaluated by tomographic coronary artery calcification index  

PubMed Central

Introduction Even in asymptomatic patients, the result of atherosclerosis progression is deterioration of the function and morphology of the artery wall. Two-dimensional speckle-tracking (2DST) is a sonographic technique that allows for precise evaluation of arterial wall compliance. Together with measurement of intima-media thickness (IMT), it can be applied for quick and non-invasive assessment of the progression of peripheral artery atherosclerosis. Material and methods Fifty-eight patients of mean age 61 years (SD 10.6) underwent cardiac computed tomography (CT) and subsequent ultrasonographic evaluation of the left common carotid artery. The calcium score was calculated according to the Agatston method and compared with IMT, circumferential strain variables assessed by 2DST, conventional arterial stiffness parameters (?-stiffness index and elastic modulus) and clinical data. Intra-observer and inter-observer agreement was evaluated. Results Strain variables and IMT differed significantly in patients with calcium score (CS) > 0 and CS = 0. Moreover, they correlated with CS, systolic blood pressure and age of patients. Conventional stiffness parameters were not able to identify the group of patients with calcifications present in the coronary arteries. For the 2DST technique, interclass and intraclass agreements were 84.83% and 94.42% respectively. Conclusions Circumferential strain variables assessed by 2DST and measurement of IMT can be used for evaluation of peripheral artery deterioration in patients until the 6th decade of life. These parameters reflect the development of calcifications in coronary arteries and, more importantly, can be used for a more detailed estimation of the atherosclerosis risk in patients with CS = 0.

Podgórski, Micha?; Szymczyk, Konrad; Szymczyk, Ewa; Dro?d?, Jaros?aw; Stefa?czyk, Ludomir

2015-01-01

126

Permeability of Dentine  

PubMed Central

This is an update on the present integrated knowledge regarding dentine permeability that assumed a role in dentine sensitivity and contribute clinically to the effective bonding properties of restorative dental materials. This paper will attempt to refer to in vivo and in vitro studies of dentine permeability and the various interrelated factors governing it. PMID:23365497

Ghazali, Farid Bin Che

2003-01-01

127

Permeability of Porous Media  

Microsoft Academic Search

OVER the past decade much significance has been given to distribution of pore size characteristics in computing both saturated and unsaturated permeability of porous materials. Oil industry investigators1 and soil scientists have adopted this approach to permeability computation with considerable success.

R. J. Millington

1959-01-01

128

Vascular imaging.  

PubMed

Many rheumatic diseases affect the vasculature, either as a 'primary' manifestation of the disease process (as in vasculitis or scleroderma-spectrum disorders) or as a result of accelerated atherosclerosis. Recent years have seen very major developments in, and refinements of, vascular imaging methods. It is likely that this pace of development will continue, enhancing the rheumatologist's ability to diagnose different musculoskeletal conditions and follow their progression, using minimally invasive techniques. In this chapter, we describe these recent advances in vascular imaging techniques, concentrating on those most relevant to the practising clinician, but also discussing methods which are being used in clinical research. Three main groups of imaging modalities are described: large vessel imaging (X-ray, magnetic resonance (MR) and computed tomography (CT) angiography), nailfold microscopy and thermography. For each of these, the method(s) and then the clinical and research applications are discussed. Laser Doppler, a research technique, is also described. PMID:15501192

Herrick, Ariane L; Hutchinson, Charles

2004-12-01

129

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 ...

130

Vascular endothelial growth factor-A: A multifunctional molecular player in diabetic retinopathy  

Microsoft Academic Search

Vascular endothelial growth factor-A (VEGF-A), first described as “vascular permeability factor”, is a critical molecule in the pathogenesis of diabetic retinopathy at several levels. Previous studies have outlined the importance of VEGF-A in mediating vascular pathology in both experimental models and clinical diabetic retinopathy, which are characterized by retinal vascular leakage, preretinal neovascularisation and neuronal degeneration. Paradoxically, recent reports have

Xinyuan Zhang; Shisan Bao; Brett D. Hambly; Mark C. Gillies

2009-01-01

131

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

132

Permeability of Concrete  

E-print Network

KU ScholarWorks | The University of Kansas Pre-1923 Dissertations and Theses Collection Permeability of Concrete June, 1911 by Harry Gardner This work was digitized by the Scholarly Communications program staff in the KU Libraries’ Center... for Digital Scholarship. http://kuscholarworks.ku.edu Submitted to the Department of Civil Engineering of the University of Kansas in partial fulfillment of the requirements for the Degree of Master of Science PERMEABILITY OF CONCRETE o Harry Gardner...

Gardner, Harry

1911-06-01

133

Estimating formation permeability  

SciTech Connect

According to a recent US national Petroleum Council survey, development of a permeability logging technique is one of the oil and gas industry's top research and development priorities. Researchers have developed a method to compute values of permeability for medium- to low-permeability (0.001 to 20 md) gas reservoirs using logging data. The method incorporates knowledge from prior research at Texas A and M University and a mudcake model developed earlier. The program models mud filtrate invasion from the time the zone is penetrated by the but until it is logged. An improvement over methods to compute permeability from time-lapse logging, it: includes an experimentally verified model for predicting the thickness and permeability of the mudcake during static and dynamic filtration conditions; and uses data from an array induction tool (AIT) log to reconstruct the invasion profile and does not require multiple time-lapse logging runs. The paper describes the methodology, data requirements, expected accuracy, a field example from a Wilcox gas zone, and an array induction tool log.

Holditch, S.A.; Diyashev, I.R.

2000-05-01

134

Glucose degradation product methylglyoxal enhances the production of vascular endothelial growth factor in peritoneal cells: role in the functional and morphological alterations of peritoneal membranes in peritoneal dialysis  

Microsoft Academic Search

Peritoneal membrane permeability deteriorates in peritoneal dialysis (PD) patients. We test whether glucose degradation products (GDPs) in PD fluids, glyoxal, methylglyoxal and 3-deoxyglucosone, stimulate the production of vascular endothelial growth factor (VEGF), a factor known to enhance vascular permeability and angiogenesis. VEGF increased in cultured rat mesothelial and human endothelial cells exposed to methylglyoxal, but not to glyoxal or 3-deoxyglucosone.

Reiko Inagi; Toshio Miyata; Takashi Yamamoto; Daisuke Suzuki; Ken-ichi Urakami; Akira Saito; Charles van Ypersele de Strihou; Kiyoshi Kurokawa

1999-01-01

135

The epidermal permeability barrier  

Microsoft Academic Search

The permeability barrier of the skin which prevents transcutaneous water loss and penetration of harmful drugs from the environment is localized in the horny layer of the epidermis. Multiple lipid bilayers obstructing the intercellular space of the stratum corneum fulfill this function. In contrast to cellular membranes consisting predominantly of phospholipids, these lamellae contain mostly ceramides, cholesterol and free fatty

Lukas Landmann

1988-01-01

136

Relative Permeability Through Fractures  

E-print Network

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

Stanford University

137

Penetrometers for Soil Permeability  

E-print Network

. The importance of soil permeability (k) is recognized as a commonly-sought parameter in the varied disciplines the routine monotonic decay of porewater pressures with time associated with soft to firm to stiff silts the opportunities to develop field testing skills related to cone, piezocone, and seismic cone penetration sounding

Mayne, Paul W.

138

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.

2012-06-26

139

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

140

EPA Permeable Surface Research - Poster  

EPA Science Inventory

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

141

Transforming Growth Factor-?1 Induces Vascular Endothelial Growth Factor Expression in Murine Proximal Tubular Epithelial Cells  

Microsoft Academic Search

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen that promotes angiogenesis, vasculogenesis, and increases vascular permeability. VEGF is expressed in renal tubular epithelial cells and urinary VEGF excretion is increased in various glomerular disorders. However, the mechanisms underlying expression of VEGF in renal tubular epithelial cells have not been fully elucidated. In the present study, we attempted

Shinji Kitamura; Yohei Maeshima; Takeshi Sugaya; Hitoshi Sugiyama; Yasushi Yamasaki; Hirofumi Makino

2003-01-01

142

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

143

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

144

Regulation of Inflammation by Fas Ligand Expression on the Vascular Endothelium  

Microsoft Academic Search

The monolayer of endothelial cells that coat the luminal surface of the vessel wall have numerous physiological functions\\u000a including the prevention of coagulation, control of vascular permeability, maintenance of vascular tone, and regulation of\\u000a leukocyte extravasation. While the vascular endothelium plays a pivotal role in recruiting inflammatory cells at the site\\u000a of infection or wounding, the normal endothelium is believed

Kenneth Walsh; Masataka Sata

145

Liquid-permeable electrode  

DOEpatents

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

Folser, George R. (Lower Burrell, PA)

1980-01-01

146

Vascular cognitive disorder: a new diagnostic category updating vascular cognitive impairment and vascular dementia.  

PubMed

Vascular cognitive impairment (VCI) was proposed as an umbrella term to include subjects affected with any degree of cognitive impairment resulting from cerebrovascular disease (CVD), ranging from mild cognitive impairment (MCI) to vascular dementia. VCI may or may not exclude the host of "focal" circumscribed impairments of specialized functions such as language (aphasia), intentional gesture (apraxia), or categorical recognition (agnosia), among others, that may result from a stroke. Therefore, there are no universally accepted diagnostic criteria for VCI. We conclude that this concept could be more useful if it were to be limited to cases of vascular MCI without dementia, by analogy with the concept of amnestic MCI, currently considered the earliest clinically diagnosable stage of Alzheimer disease (AD). In agreement with our view,the Canadian Study on Health and Aging successfully implemented a restricted definition of VCI, excluding cases of dementia (i.e., vascular cognitive impairment no dementia, VCI-ND). The Canadian definition and diagnostic criteria could be utilized for future studies of VCI. This definition excludes isolated impairments of specialized cognitive functions. Vascular dementia (VaD): The main problem of this diagnostic category stems from the currently accepted definition of dementia that requires memory loss as the sine qua non for the diagnosis. This may result in over-sampling of patients with AD worsened by stroke (AD+CVD). This problem was minimized in controlled clinical trials of VaD by excluding patients with a prior diagnosis of AD, those with pre-existing memory loss before the index stroke, and those with amnestic MCI. We propose a definition of dementia in VaD based on presence of abnormal executive control function, severe enough to interfere with social or occupational functioning. Vascular cognitive disorder (VCD): This term, proposed by Sachdev [P. Sachdev, Vascular cognitive disorder. Int J Geriat Psychiatry 14 (1999)402-403.] would become the global diagnostic category for cognitive impairment of vascular origin, ranging from VCI to VaD. It would include specific disease entities such as post-stroke VCI, post-stroke VaD, CADASIL, Binswanger disease, and AD plus CVD. This category explicitly excludes isolated cognitive dysfunctions such as those mentioned above. PMID:15537526

Román, Gustavo C; Sachdev, Perminder; Royall, Donald R; Bullock, Roger A; Orgogozo, Jean-Marc; López-Pousa, Secundino; Arizaga, Raul; Wallin, Anders

2004-11-15

147

A Computer Numerical Simulation Study Considering Starting Up Pressure Gradient for Low Permeability Reservoir  

Microsoft Academic Search

According to the fact that starting up pressure gradient exists when fluids flow in low permeability reservoir, a nondarcy flow mathematical model is established, in which the factor of starting up pressure gradient is included for low permeability reservoir. Software, by solving the partial differential equations by difference method, is developed, and is used to calculate development index and the

Daiyin Yin; Weiming Huang

2009-01-01

148

Permeability evolution during progressive development of deformation bands in porous sandstones  

E-print Network

: Permeability and porosity; 5139 Physical Properties of Rocks: Transport properties; 8010 Structural Geology. INDEX TERMS: 5112 Physical Properties of Rocks: Microstructure; 5114 Physical Properties of Rocks in predicting fault permeability and sealing potential as a function of burial depth and fault displacement

149

Three-dimensional array of dielectric spheres with an isotropic negative permeability at infrared frequencies  

E-print Network

Three-dimensional array of dielectric spheres with an isotropic negative permeability at infrared to the bulk response of the composite. The derived permittivity and permeability are shown to be isotropic index of refraction metamaterials1 and their exciting applications, such as the perfect lens,2 have

Mojahedi, Mohammad

150

Society for Vascular Medicine  

MedlinePLUS

... Annual Meeting Events Calendar Vascular Medicine Events Job Bank Professional Practice Position Statements PAD Awareness Vascular Related ... for a new job? Try the SVM Job Bank . Browse the jobs or sign up for job ...

151

Soluble receptor for advanced glycation end products as an indicator of pulmonary vascular injury after cardiac surgery  

PubMed Central

Background Cardiac surgery is frequently complicated by an acute vascular lung injury and this may be mediated, at least in part, by the (soluble) receptor for advanced glycation end products (sRAGE). Methods In two university hospital intensive care units, circulating sRAGE was measured together with the 68Gallium-transferrin pulmonary leak index (PLI), a measure of pulmonary vascular permeabiliy, in 60 consecutive cardiac surgery patients stratified by the amount of blood transfusion, within 3 hours of admission to the intensive care. Results Cardiac surgery resulted in elevated plasma sRAGE levels compared to baseline (315?±?181 vs 110?±?55 pg/ml, P?=?0.001). In 37 patients the PLI was elevated 50% above normal. The PLI correlated with sRAGE (r2?=?0.11, P?=?0.018). Plasma sRAGE discriminated well between those with an elevated PLI and those with a normal PLI (area under the operator curve 0.75; P?=?0.035; 95% CI 0.55-0.95), with 91% sensitivity but low specificity of 36% at a cutoff value of 200 pg/mL. Blood transfusion did not influence sRAGE levels. Conclusions sRAGE is elevated in plasma after cardiac surgery and indicates increased pulmonary vascular permeability. The level of sRAGE is not affected by transfusion. PMID:24341821

2013-01-01

152

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

153

Angiopoietin-2 is critical for cytokine-induced vascular leakage.  

PubMed

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

Benest, Andrew V; Kruse, Karoline; Savant, Soniya; Thomas, Markus; Laib, Anna M; Loos, Elias K; Fiedler, Ulrike; Augustin, Hellmut G

2013-01-01

154

Modeling of Microvascular Permeability Changes after Electroporation  

PubMed Central

Vascular endothelium selectively controls the transport of plasma contents across the blood vessel wall. The principal objective of our preliminary study was to quantify the electroporation-induced increase in permeability of blood vessel wall for macromolecules, which do not normally extravasate from blood into skin interstitium in homeostatic conditions. Our study combines mathematical modeling (by employing pharmacokinetic and finite element modeling approach) with in vivo measurements (by intravital fluorescence microscopy). Extravasation of fluorescently labeled dextran molecules of two different sizes (70 kDa and 2000 kDa) following the application of electroporation pulses was investigated in order to simulate extravasation of therapeutic macromolecules with molecular weights comparable to molecular weight of particles such as antibodies and plasmid DNA. The increase in blood vessel permeability due to electroporation and corresponding transvascular transport was quantified by calculating the apparent diffusion coefficients for skin microvessel wall (D [?m2/s]) for both molecular sizes. The calculated apparent diffusion coefficients were D = 0.0086 ?m2/s and D = 0.0045 ?m2/s for 70 kDa and 2000 kDa dextran molecules, respectively. The results of our preliminary study have important implications in development of realistic mathematical models for prediction of extravasation and delivery of large therapeutic molecules to target tissues by means of electroporation. PMID:25793292

Corovic, Selma; Markelc, Bostjan; Dolinar, Mitja; Cemazar, Maja; Jarm, Tomaz

2015-01-01

155

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.

Rebecca Witherow

156

Retina vascular network recognition  

NASA Astrophysics Data System (ADS)

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

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

1993-09-01

157

Permeability and Relative Permeability in Rocks Stephen C. Blair  

E-print Network

Permeability and Relative Permeability in Rocks Stephen C. Blair James G. Berryman University 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 cor­ relation functions using modern

158

Macrophage migration inhibitory factor induces vascular leakage via autophagy  

PubMed Central

ABSTRACT Vascular leakage is an important feature of acute inflammatory shock, which currently has no effective treatment. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that can induce vascular leakage and plays an important role in the pathogenesis of shock. However, the mechanism of MIF-induced vascular leakage is still unclear. In this study, using recombinant MIF (rMIF), we demonstrated that MIF induced disorganization and degradation of junction proteins and increased the permeability of human endothelial cells in vitro. Western blotting analysis showed that rMIF treatment induced LC3 conversion and p62 degradation. Inhibition of autophagy with a PI3K inhibitor (3-MA), a ROS scavenger (NAC) or autophagosomal-lysosomal fusion inhibitors (bafilomycin A1 and chloroquine) rescued rMIF-induced vascular leakage, suggesting that autophagy mediates MIF-induced vascular leakage. The potential involvement of other signaling pathways was also studied using different inhibitors, and the results suggested that MIF-induced vascular leakage may occur through the ERK pathway. In conclusion, we showed that MIF triggered autophagic degradation of endothelial cells, resulting in vascular leakage. Inhibition of MIF-induced autophagy may provide therapeutic targets against vascular leakage in inflammatory shock. PMID:25617421

Chen, Hong-Ru; Chuang, Yung-Chun; Chao, Chiao-Hsuan; Yeh, Trai-Ming

2015-01-01

159

Macrophage migration inhibitory factor induces vascular leakage via autophagy.  

PubMed

Vascular leakage is an important feature of acute inflammatory shock, which currently has no effective treatment. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that can induce vascular leakage and plays an important role in the pathogenesis of shock. However, the mechanism of MIF-induced vascular leakage is still unclear. In this study, using recombinant MIF (rMIF), we demonstrated that MIF induced disorganization and degradation of junction proteins and increased the permeability of human endothelial cells in vitro. Western blotting analysis showed that rMIF treatment induced LC3 conversion and p62 degradation. Inhibition of autophagy with a PI3K inhibitor (3-MA), a ROS scavenger (NAC) or autophagosomal-lysosomal fusion inhibitors (bafilomycin A1 and chloroquine) rescued rMIF-induced vascular leakage, suggesting that autophagy mediates MIF-induced vascular leakage. The potential involvement of other signaling pathways was also studied using different inhibitors, and the results suggested that MIF-induced vascular leakage may occur through the ERK pathway. In conclusion, we showed that MIF triggered autophagic degradation of endothelial cells, resulting in vascular leakage. Inhibition of MIF-induced autophagy may provide therapeutic targets against vascular leakage in inflammatory shock. PMID:25617421

Chen, Hong-Ru; Chuang, Yung-Chun; Chao, Chiao-Hsuan; Yeh, Trai-Ming

2015-01-01

160

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

Microsoft Academic Search

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

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

2008-01-01

161

Ca2+ signaling, TRP channels, and endothelial permeability.  

PubMed

Increased endothelial permeability is the hallmark of inflammatory vascular edema. Inflammatory mediators that bind to heptahelical G protein-coupled receptors trigger increased endothelial permeability by increasing the intracellular Ca2+ concentration ([Ca2+]i). The rise in [Ca2+]i activates key signaling pathways that mediate cytoskeletal reorganization (through myosin-light-chain-dependent contraction) and the disassembly of VE-cadherin at the adherens junctions. The Ca2+-dependent protein kinase C (PKC) isoform PKCalpha plays a crucial role in initiating endothelial cell contraction and disassembly of VE-cadherin junctions. The increase in [Ca2+]i induced by inflammatory agonists such as thrombin and histamine is achieved by the generation of inositol 1,4,5-trisphosphate (IP3), activation of IP3-receptors, release of stored intracellular Ca2+, and Ca2+ entry through plasma membrane channels. IP3-sensitive Ca2+-store depletion activates plasma membrane cation channels (i.e., store-operated cation channels [SOCs] or Ca2+ release-activated channels [CRACs]) to cause Ca2+ influx into endothelial cells. Recent studies have identified members of Drosophila transient receptor potential (TRP) gene family of channels that encode functional SOCs in endothelial cells. These studies also suggest that the canonical TRPC homologue TRPC1 is the predominant isoform expressed in human vascular endothelial cells, and is the essential component of the SOC in this cell type. Further, evidence suggests that the inflammatory cytokine tumor necrosis factor-alpha can induce the expression of TRPC1 in human vascular endothelial cells signaling via the nuclear factor-kappaB pathway. Increased expression of TRPC1 augments Ca2+ influx via SOCs and potentiates the thrombin-induced increase in permeability in human vascular endothelial cells. Deletion of the canonical TRPC homologue in mouse, TRPC4, caused impairment in store-operated Ca2+ current and Ca2+-store release-activated Ca2+ influx in aortic and lung endothelial cells. In TRPC4 knockout (TRPC4-/-) mice, acetylcholine-induced endothelium-dependent smooth muscle relaxation was drastically reduced. In addition, TRPC4-/- mouse-lung endothelial cells exhibited lack of actin-stress fiber formation and cell retraction in response to thrombin activation of protease-activated receptor-1 (PAR-1) in endothelial cells. The increase in lung microvascular permeability in response to PAR-1 activation was inhibited in TRPC4-/- mice. These results indicate that endothelial TRP channels such as TRPC1 and TRPC4 play an important role in signaling agonist-induced increases in endothelial permeability. PMID:17085428

Tiruppathi, Chinnaswamy; Ahmmed, Gias U; Vogel, Stephen M; Malik, Asrar B

2006-12-01

162

VEGF increases blood–brain barrier permeability to Evans blue dye and tetanus toxin fragment C but not adeno-associated virus in ALS mice  

Microsoft Academic Search

Entry of most compounds into the CNS is impeded by the blood–brain barrier (BBB). Because vascular endothelial growth factor (VEGF) is important in the formation and maintenance of the BBB and is known to modulate BBB permeability in newborn rodents, we tested the hypothesis that VEGF may enhance BBB permeability in adult mice. We examined the effect of VEGF on

Ilknur Ay; Jonathan W. Francis; Robert H. Brown

2008-01-01

163

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

164

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.

165

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

166

AKAP12 regulates vascular integrity in zebrafish  

PubMed Central

The integrity of blood vessels controls vascular permeability and extravasation of blood cells, across the endothelium. Thus, the impairment of endothelial integrity leads to hemorrhage, edema, and inflammatory infiltration. However, the molecular mechanism underlying vascular integrity has not been fully understood. Here, we demonstrate an essential role for A-kinase anchoring protein 12 (AKAP12) in the maintenance of endothelial integrity during vascular development. Zebrafish embryos depleted of akap12 (akap12 morphants) exhibited severe hemorrhages. In vivo time-lapse analyses suggested that disorganized interendothelial cell-cell adhesions in akap12 morphants might be the cause of hemorrhage. To clarify the molecular mechanism by which the cell-cell adhesions are impaired, we examined the cell-cell adhesion molecules and their regulators using cultured endothelial cells. The expression of PAK2, an actin cytoskeletal regulator, and AF6, a connector of intercellular adhesion molecules and actin cytoskeleton, was reduced in AKAP12-depleted cells. Depletion of either PAK2 or AF6 phenocopied AKAP12-depleted cells, suggesting the reduction of PAK2 and AF6 results in the loosening of intercellular junctions. Consistent with this, overexpression of PAK2 and AF6 rescued the abnormal hemorrhage in akap12 morphants. We conclude that AKAP12 is essential for integrity of endothelium by maintaining the expression of PAK2 and AF6 during vascular development. PMID:22192928

Kwon, Hyouk-Bum; Choi, Yoon Kyung; Lim, Jhong-Jae; Kwon, Seung-Hae; Her, Song; Kim, Hyun-Jin; Lim, Kyung-Joon; Ahn, Jong-Chan; Kim, Young-Myeong; Bae, Moon-Kyung; Park, Jeong Ae; Jeong, Chul-Ho; Mochizuki, Naoki

2012-01-01

167

Bradykinin is degraded in hypoxic lungs and does not affect epithelial permeability  

Microsoft Academic Search

To investigate the effect of intravenous infusions of bradykinin (BK) on the permeability of the hypoxic pulmonary epithelium to small solutes, experiments (n = 7) were performed in yearling sheep with chronic vascular catheters. Sheep were anesthetized, intubated, paralyzed, and ventilated. After establishing stable and normal base-line pulmonary hemodynamics and blood gas tensions, the lungs were insufflated with a submicronic

H. OBrodovich; J. Kay; G. Coates

1985-01-01

168

Expression of vascular endothelial growth factor in von hippel-lindau syndrome-associated papillary cystadenoma of the epididymis  

Microsoft Academic Search

Vascular endothelial growth factor (VEGF) is a hypoxia inducible angiogenic and vascular permeability factor. Although VEGF expression in glioblastoma is induced by hypoxia, its expression in renal cell carcinoma and hemangioblastoma is thought to be related to mutation of the von Hippel-Lindau (VHL) gene. It is not certain whether other lesions in VHL syndrome are associated with an elevated VEGF

Suet Yi Leung; Annie Shuk Yee Chan; Maria P Wong; Siu Tsan Yuen; Yiu Wah Fan; Lap Ping Chung

1998-01-01

169

Permeability of rheumatoid and normal human synovium to specific plasma proteins.  

PubMed

A method is described for the determination of the permeability of the blood-joint barrier to specific plasma proteins, using the ratio of protein concentration in synovial fluid to that in plasma. The inadequacy of the ratio per se as a direct index of permeability is discussed. Permeabilities are evaluated for the normal and rheumatoid human knee. Permeability increases in the rhematoid knee by approximately 6 times for the rheumatoid knee by approximately 6 times for albumin and over 40 times for macroglobulins. The effect of protein molecular dimensions upon permeability is analyzed. Permeability shows less dependence upon solute dimensions in the rheumatoid knee than in the normal knee, i.e., molecular selectivity is reduced. From these data and synovial morphology, a two-membrane model of the blood-joint barrier is developed. The relative contribution of the component intimal and endothelial layers to the total barrier is found to depend upon solute dimensions. PMID:7326067

Levick, J R

1981-12-01

170

Histopathology of vascular anomalies.  

PubMed

Vascular anomalies may be appropriately classified into two broad categories, vascular tumors and vascular malformations, which are distinguished by the presence of cellular proliferation in contrast to aberrations in morphogenesis, respectively. This system of classification is based upon histological features that may in large part be differentiating, but nevertheless, may show morphological overlap. Advances in immunophenotyping allow for more precise diagnoses as well as further delineation of cell origins. In the discussion, we present the clinical, histological, and, when applicable, the immunophenotypic presentation of vascular anomalies commonly seen in infancy and early childhood. PMID:23188681

Aboutalebi, Amir; Jessup, Chad J; North, Paula E; Mihm, Martin C

2012-12-01

171

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 removal processes is at work. KEYWORDS: nitrate removal, denitrification, permeable reactive barrier

Vallino, Joseph J.

172

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

PubMed Central

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

DiStasi, Matthew R.; Ley, Klaus

2009-01-01

173

Vascularity assessment of thyroid nodules by quantitative color Doppler ultrasound.  

PubMed

Our objective was to assess the role of quantitative Doppler vascularity in differentiating malignant and benign thyroid nodules. Color Doppler images of 100 nodules were analyzed for three metrics: vascular fraction area, mean flow velocity index and flow volume index in three regions (nodule center, nodule rim and surrounding parenchyma). Vascular fraction area and flow volume index were higher in malignant than benign nodules in both the central and rim regions, whereas flow velocity index was equivalent in both regions. Of the three vascularity metrics studied, the vascular fraction area of the central region was most effective in predicting malignancy, with a sensitivity of 0.90 ± 0.05, specificity of 0.88 ± 0.13, positive predictive value of 0.84 ± 0.14, negative predictive value of 0.92 ± 0.03 and accuracy of 0.89 ± 0.08. Quantitative Doppler vascularity of the nodule center yielded a high level of discrimination between benign and malignant nodules and, thus, has the greatest potential to contribute to gray-scale assessment of thyroid cancer. PMID:25677641

Sultan, Laith R; Xiong, Hui; Zafar, Hanna M; Schultz, Susan M; Langer, Jill E; Sehgal, Chandra M

2015-05-01

174

Relative Permeability of Fractured Rock  

SciTech Connect

Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

Mark D. Habana

2002-06-30

175

Structural mechanisms of acute VEGF effect on microvessel permeability.  

PubMed

To investigate the ultrastructural mechanisms of acute microvessel hyperpermeability by vascular endothelial growth factor (VEGF), we combined a mathematical model (J Biomech Eng 116: 502-513, 1994) with experimental data of the effect of VEGF on microvessel hydraulic conductivity (L(p)) and permeability of various-sized solutes. We examined the effect of VEGF on microvessel permeability to a small solute (sodium fluorescein, Stokes radius 0.45 nm), an intermediate solute (alpha-lactalbumin, Stokes radius 2.01 nm), and a large solute [albumin (BSA), Stokes radius 3.5 nm]. Exposure to 1 nM VEGF transiently increased apparent permeability to 2.3, 3.3, and 6.2 times their baseline values for sodium fluorescein, alpha-lactalbumin, and BSA, respectively, within 30 s, and all returned to control within 2 min. On the basis of L(p) (DO Bates and FE Curry. Am J Physiol Heart Circ Physiol 271: H2520-H2528, 1996) and permeability data, the prediction from the model suggested that the most likely structural changes in the interendothelial cleft induced by VEGF would be a approximately 2.5-fold increase in its opening width and partial degradation of the surface glycocalyx. PMID:12560209

Fu, Bingmei M; Shen, Shang

2003-06-01

176

Ceramide alters endothelial cell permeability by a nonapoptotic mechanism  

PubMed Central

Ceramide is a lipid second messenger that was recently identified as mediator of pulmonary edema in vivo. Here, we investigated the effect of ceramide on the permeability of confluent endothelial cell monolayers. In monolayers of bovine pulmonary artery and human microvascular pulmonary endothelial cells, incubation with C6-ceramide for 3?h elevated permeability in a concentration-dependent manner, whereas dihydroceramide was without effect. After 3?h of incubation with ceramide, we found no signs of necrosis (release of lactate dehydrogenase, loss of thiazylyl blue reduction) or apoptosis (ssDNA, caspase-8 activity). The increased endothelial permeability in response to ceramide was attenuated by the Ser/Thr protein kinase inhibitors K252a, K252b and H-7, as well as by the phosphatidylinositol-specific phospholipase C inhibitor L108. Since in some systems sphingosine-1-phosphate (S1P) acts antagonistic to ceramide, the effect of S1P was studied. S1P transiently increased endothelial cell resistance, whether it was given together with ceramide or 90?min thereafter. These data provide a novel example of the antagonism between S1P and ceramide. Our findings further suggest that ceramide alters vascular permeability by activation of pathways dependent on unidentified phospholipase C and Ser/Thr kinase isoenzymes. PMID:15735657

Lindner, Karsten; Uhlig, Ulrike; Uhlig, Stefan

2005-01-01

177

Vascular Plant Image Gallery  

NSDL National Science Digital Library

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

Manhart, James R.

178

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

179

Evolution of Fracture Permeability  

NASA Astrophysics Data System (ADS)

Pore fluid flow and fluid composition within fractured rocks is a subject of primary importance to fields including hazardous waste isolation and remediation, oil and gas production, geothermal energy extraction, and formation of vein fillings and ore deposits. For these reasons, considerable effort has been placed on characterization and modeling of flow in fractures and fracture systems. We are investigating the complex active chemical interaction between pore fluid and fractures that causes the fluid composition and topography of these systems to change over time. Our experimental model consists of CaSO4 samples pressed with a constant force against an inert textured fracture surface. Pore fluids ranging from unsaturated to supersaturated which are at a variety of flow rates are introduced to one end of the sample in order to actively alter the topography of the CaSO4 surface. Using a laser profiler, we are able to quantitatively monitor the changing surface topography over time as it relates to the measured sample permeability and calcium saturation of the pore fluid. These methods allow us to create and analyze many features seen in natural fractures, including high-flow dissolution channels, plateaus, and caverns formed from precipitate. In addition, the laser profile of the sample surface can be used to produce a map of aperture across the sample. Using this information, we have applied numerical modeling via finite difference and lattice Boltzmann methods to calculate pore fluid flow direction and magnitude over the entire sample surface. This research is part of an integrated program using quantitative observations of fractures and veins in drill core as well as quantitative and visual observations of flow and chemical dissolution and precipitation within replicas of rough-walled fractures in order to refine our models and work toward a predictive capability.

Ebel, K. A.; Brown, S. R.

2003-12-01

180

PERMEABLE JUNCTIONAL COMPLEXES  

PubMed Central

Ionic lanthanum has been used to study transepithelial ion permeation in in vitro rabbit gallbladder and intestine (ileum) by adding 1 mM La3+ to only the mucosal bathing solution. Transepithelial fluid transport electrical potential differences (p.d.), and resistances were measured. During La3+ treatment the gallbladder's rate of active solute-coupled fluid transport remained constant, the resistance increased, and the 2:1 NaCl diffusion p.d. decreased. Mucosa-to-serosa fluxes of 140La3+ were measured and indicate a finite permeability of the gallbladder to La3+. La3+ also increased the transepithelial resistance and p d. of ileum. Electron microscopic examination of La3+-treated gallbladder showed: (a) good preservation of the fine structure, (b) electron-opaque lanthanum precipitates in almost every lateral intercellular space, most frequently near the apical end of the lateral spaces close to or within the junctional complex, (c) lanthanum among the subjacent muscle and connective tissue layers, and (d) lanthanum filling almost the entire length of so-called "tight" junctions. No observations were made which unequivocally showed the penetration of lanthanum into the gallbladder cells. Electron micrographs of similar La3+-treated ilea showed lanthanum deposits penetrating the junctional complexes. These results coupled with other physiological studies indicate that the low resistance pathway for transepithelial ion permeation in gallbladder and ileum is through the tight junctions A division of salt-transporting epithelia into two main groups, those with "leaky" junctional complexes and those with tight junctional complexes, has been proposed. PMID:5040861

Machen, Terry E.; Erlij, David; Wooding, F. B. P.

1972-01-01

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

Small intestinal permeability in older adults.  

PubMed

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

183

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

184

Indexing Images.  

ERIC Educational Resources Information Center

Focuses on access to digital image collections by means of manual and automatic indexing. Contains six sections: (1) Studies of Image Systems and their Use; (2) Approaches to Indexing Images; (3) Image Attributes; (4) Concept-Based Indexing; (5) Content-Based Indexing; and (6) Browsing in Image Retrieval. Contains 105 references. (AEF)

Rasmussen, Edie M.

1997-01-01

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

Cytoskeletal mechanisms regulating vascular endothelial barrier function in response to acute lung injury.  

PubMed

Endothelial cells (EC) form a semi-permeable barrier between the interior space of blood vessels and the underlying tissues. In acute lung injury (ALI) the EC barrier is weakened leading to increased vascular permeability. It is widely accepted that EC barrier integrity is critically dependent upon intact cytoskeletal structure and cell junctions. Edemagenic agonists, like thrombin or endotoxin lipopolysaccharide (LPS), induced cytoskeletal rearrangement, and EC contractile responses leading to disruption of intercellular contacts and EC permeability increase. The highly clinically-relevant cytoskeletal mechanisms of EC barrier dysfunction are currently under intense investigation and will be described and discussed in the current review. PMID:25838980

Kása, Anita; Csortos, Csilla; Verin, Alexander D

2015-01-01

187

Congenital Vascular Malformation  

MedlinePLUS

... and Anomalies Vascular anomalies occur in barely 1 percent of all births. Yet, because of their rarity, their proper diagnosis and treatment is difficult, as most physicians do not see these problems often enough to become knowledgeable about their management. ...

188

What Is Vascular Disease?  

MedlinePLUS

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

189

Vascular Access Procedures  

MedlinePLUS

... period of weeks, months or even years. A simple intravenous (IV) line is effective for short-term ... blood transfusions. patients who have difficulty receiving a simple IV line. Vascular access procedures are also commonly ...

190

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

191

Effects of Flow Patterns on the Localization and Expression of VE-Cadherin at Vascular Endothelial Cell Junctions: In vivo and in vitro Investigations  

Microsoft Academic Search

Atherosclerosis occurs preferentially at vascular curvature and branch sites where the vessel walls are exposed to fluctuating shear stress and have high endothelial permeability. Endothelial permeability is modulated by intercellular adhesion molecules such as VE-cadherin. This study was designed to elucidate the effects of different flow patterns on the localization and expression of VE-cadherin in endothelial cells (ECs) both in

Hui Miao; Ying-Li Hu; Yan-Ting Shiu; Suli Yuan; Yihua Zhao; Roland Kaunas; Yingxiao Wang; Gang Jin; Shunichi Usami; Shu Chien

2005-01-01

192

Congenital vascular anomalies  

Microsoft Academic Search

Opinion statement  Congenital vascular anomalies are rare. The cardiovascular specialist should nevertheless be aware of the more common types\\u000a of vascular anomalies and understand the implications for patient treatment and the likelihood of associated morbidity. The\\u000a presentation of congenital arteriovenous malformations can range from asymptomatic or cosmetic lesions, to those causing ischemia,\\u000a ulceration, hemorrhage, or high-output congestive heart failure. Treatment of

Edwin C. Gravereaux; Louis L. Nguyen; Leslie D. Cunningham

2004-01-01

193

Vascular Microenvironment in Gliomas  

Microsoft Academic Search

\\u000a Structural and functional abnormalities of the vascular microenvironment determine pathophysiological characteristics of gliomas,\\u000a such as loss of blood-brain barrier function, tumor cell invasiveness, or permselectivity for large molecules. Moreover, the\\u000a effectiveness of various therapeutic strategies critically depends upon the successful transvascular delivery of molecules.\\u000a In order to shed more light on the vascular microenvironment in gliomas, a variety of experimental

Peter Vajkoczy; Michael D. Menger

194

International Plant Names Index (IPNI)  

NSDL National Science Digital Library

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

195

Vascular Cognitive Deterioration and Stroke  

Microsoft Academic Search

Vascular cognitive impairment, the recent modification of the terminology related to vascular burden of the brain, reflects the all-encompassing effects of vascular disease or lesions on cognition. It incorporates the complex interactions between vascular aetiologies, risk factors and cellular changes within the brain and cognition. The concept covers the frequent poststroke cognitive impairment and dementia, as well as cerebrovascular disease

Timo Erkinjuntti

2007-01-01

196

Vascular endothelial growth factor-dependent angiogenesis and dynamic vascular plasticity in the sensory circumventricular organs of adult mouse brain.  

PubMed

The sensory circumventricular organs (CVOs), which comprise the organum vasculosum of the lamina terminalis (OVLT), the subfornical organ (SFO) and the area postrema (AP), lack a typical blood-brain barrier (BBB) and monitor directly blood-derived information to regulate body fluid homeostasis, inflammation, feeding and vomiting. Until now, almost nothing has been documented about vascular features of the sensory CVOs except fenestration of vascular endothelial cells. We therefore examine whether continuous angiogenesis occurs in the sensory CVOs of adult mouse. The angiogenesis-inducing factor vascular endothelial growth factor-A (VEGF-A) and the VEGF-A-regulating transcription factor hypoxia-inducible factor-1? were highly expressed in neurons of the OVLT and SFO and in both neurons and astrocytes of the AP. Expression of the pericyte-regulating factor platelet-derived growth factor B was high in astrocytes of the sensory CVOs. Immunohistochemistry of bromodeoxyuridine and Ki-67, a nuclear protein that is associated with cellular proliferation, revealed active proliferation of endothelial cells. Moreover, immunohistochemistry of caspase-3 and the basement membrane marker laminin showed the presence of apoptosis and sprouting of endothelial cells, respectively. Treatment with the VEGF receptor-associated tyrosine kinase inhibitor AZD2171 significantly reduced proliferation and filopodia sprouting of endothelial cells, as well as the area and diameter of microvessels. The mitotic inhibitor cytosine-b-D-arabinofuranoside reduced proliferation of endothelial cells and the vascular permeability of blood-derived low-molecular-weight molecules without changing vascular area and microvessel diameter. Thus, our data indicate that continuous angiogenesis is dependent on VEGF signaling and responsible for the dynamic plasticity of vascular structure and permeability. PMID:25573819

Morita, Shoko; Furube, Eriko; Mannari, Tetsuya; Okuda, Hiroaki; Tatsumi, Kouko; Wanaka, Akio; Miyata, Seiji

2015-03-01

197

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

SciTech Connect

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

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

2007-12-01

198

Autophagy in vascular disease.  

PubMed

Autophagy is a reparative, life-sustaining process by which cytoplasmic components are sequestered in double-membrane vesicles and degraded on fusion with lysosomal compartments. Growing evidence reveals that basal autophagy is an essential in vivo process mediating proper vascular function. Moreover, autophagy is stimulated by many stress-related stimuli in the arterial wall to protect endothelial cells and smooth muscle cells against cell death and the initiation of vascular disease, in particular atherosclerosis. Basal autophagy is atheroprotective during early atherosclerosis but becomes dysfunctional in advanced atherosclerotic plaques. Little is known about autophagy in other vascular disorders, such as aneurysm formation, arterial aging, vascular stiffness, and chronic venous disease, even though autophagy is often impaired. This finding highlights the need for pharmacological interventions with compounds that stimulate the prosurvival effects of autophagy in the vasculature. A large number of animal studies and clinical trials have indicated that oral or stent-based delivery of the autophagy inducer rapamycin or derivatives thereof, collectively known as rapalogs, effectively inhibit the basic mechanisms that control growth and destabilization of atherosclerotic plaques. Other autophagy-inducing drugs, such as spermidine or add-on therapy with widely used antiatherogenic compounds, including statins and metformin, are potentially useful to prevent vascular disease with minimal adverse effects. PMID:25634970

De Meyer, Guido R Y; Grootaert, Mandy O J; Michiels, Cédéric F; Kurdi, Ammar; Schrijvers, Dorien M; Martinet, Wim

2015-01-30

199

Role of vascular endothelial growth factor in endometrial vascular events before implantation in rats.  

PubMed

Two endometrial vascular events, increased permeability and endothelial cell proliferation, characterize the early stages of embryo implantation in rats. Vascular endothelial growth factor (VEGF), a heparin-binding homodimeric glycoprotein, is expressed in the uterus at the time of implantation. The aim of this study was to investigate the effects of systemic administration of blocking antibody to VEGF on endometrial vascular permeability and endothelial cell proliferation around the time of embryo implantation in rats. Rats were injected i.p. with 1.0, 0.8 or 0.6 ml of anti-VEGF antibody or control serum on day 3 of pregnancy and Evans blue dye was administered i.v. on day 5 of pregnancy. The number of implantation sites (blue bands along the uterus) was counted and endothelial cell proliferation was identified using double staining immunohistochemistry. The number of blue bands was significantly lower (P < 0.05) after injection of 1.0 ml blocking antibody (1.8 +/- 1.56) compared with that in control rats (11.6 +/- 1.97). The number of blue bands was significantly different among rats injected with 1.0 (1.8 +/- 1.56), 0.8 (6.0 +/- 3.67) or 0.6 (10.7 +/- 0.33) ml anti-VEGF antibody, indicating a concentration effect of anti-VEGF antibody. No significant differences in endothelial cell proliferation at embryo implantation sites were observed after injection with anti-VEGF antibody or control serum. At intersites (uterine zones between the blue bands), injection of 0.6 ml anti-VEGF antibody caused a significant reduction (P < 0.05) in the percentage of vessels with proliferating endothelial cells (7.25 +/- 2.39%), with a non-significant reduction using 1.0 or 0.8 ml anti-VEGF antibody. No significant differences in microvascular density at either embryo implantation sites or intersites were observed between rats injected with anti-VEGF antibody or control serum. In conclusion, VEGF is the main factor responsible for increased endometrial vascular permeability at implantation. It may regulate endometrial endothelial cell proliferation before implantation and at intersites, thus indicating that factors or mechanisms other than VEGF may regulate endothelial cell proliferation at the site of implantation. PMID:11425332

Rabbani, M L; Rogers, P A

2001-07-01

200

Changes in Gastric Mucosal Morphology, Capillary Permeability and Blood Flow during the First 3 Days of Acute Gastritis in Cats  

Microsoft Academic Search

In the present investigation gastric morphology, blood flow, vascular permeability and water content were studied in cat stomachs with acetic acid-induced gastritis at different time intervals up to 3 days after induction of gastritis. The morphological changes including mucosal erosions, edema and hemorrhage showed normalization within 3 days. The mucosa and muscularis blood flow remained essentially unchanged compared with pre-gastritis

O. Søreide; K. Svanes; J. E. Varhaug; A. Skarstein

1980-01-01

201

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

202

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

203

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

204

Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock  

PubMed Central

Abstract 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.

2013-01-01

205

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

206

Fracture permeability and seismic wave scattering ŒPoroelastic ...  

E-print Network

Jun 18, 2010 ... with a range of permeability (Nakagawa and Schoenberg, 2007). ... the effective stress law, which includes the Biot-Willis coefficient ?. The final ..... permeability materials, I. Governing equations and acoustic attenuation: Phys.

Seiji Nakagawa

2010-02-03

207

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. ...

208

Endothelial cell permeability and adherens junction disruption induced by junín virus infection.  

PubMed

Junín virus (JUNV) is endemic to the fertile Pampas of Argentina, maintained in nature by the rodent host Calomys musculinus, and the causative agent of Argentine hemorrhagic fever (AHF), which is characterized by vascular dysfunction and fluid distribution abnormalities. Clinical as well as experimental studies implicate involvement of the endothelium in the pathogenesis of AHF, although little is known of its role. JUNV has been shown to result in productive infection of endothelial cells (ECs) in vitro with no visible cytopathic effects. In this study, we show that direct JUNV infection of primary human ECs results in increased vascular permeability as measured by electric cell substrate impedance sensing and transwell permeability assays. We also show that EC adherens junctions are disrupted during virus infection, which may provide insight into the role of the endothelium in the pathogenesis of AHF and possibly, other viral hemorrhagic fevers. PMID:24710609

Lander, Heather M; Grant, Ashley M; Albrecht, Thomas; Hill, Terence; Peters, Clarence J

2014-06-01

209

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

210

Effect of perfusate hematocrit on urea permeability-surface area in isolated dog lung  

SciTech Connect

Seven dog lower left lung lobes were statically inflated and perfused at a constant rate for each lobe with a perfusate in which the hematocrit was altered over a wide range. The permeability-surface area of urea was calculated from multiple indicator dilution curves using two separate injectates for each hematocrit level. One injectate contained only /sup 125/I-albumin as the vascular reference tracer and the other contained both /sup 51/Cr-erythrocytes and /sup 125/I-albumin as the vascular reference tracers; both contained (/sup 14/C)urea as the permeating tracer. The results strongly indicate that the phenomenon of erythrocyte trapping of urea does not affect the calculation of urea permeability-surface area product provided the appropriate albumin-erythrocyte composite reference tracer is utilized in its calculation.

Parker, R.E.; Roselli, R.J.; Haselton, F.R.; Harris, T.R.

1986-10-01

211

Increased arterial vascular tone during the night in patients with essential hypertension  

Microsoft Academic Search

The time-dependent incidence of cardiovascular events points to an important role of chronobiology for arterial properties. To evaluate arterial properties in patients with essential hypertension, we assessed arterial vascular tone during sleep at night in patients with essential hypertension and normotensive control subjects. Vascular tone was continuously quantified by the reflective index obtained by non-invasive digital photoplethysmography and an algorithm

A Scholze; A Burkert; K Mardanzai; S Suvd-Erdene; M Hausberg; W Zidek; M Tepel

2007-01-01

212

A protease-like permeability factor in guinea pig skin: immunologic identity with plasma Hageman factor.  

PubMed Central

Vascular permeability enhancement activity of the protease-like permeability factor derived from guinea pig skin and of active guinea pig Hageman factor (beta HFa) were both inhibited by anti-guinea pig Hageman factor rabbit F(ab')2 antibody. The permeability activity of both factors was also absorbed on anti-Hageman factor F(ab')2-Sepharose beads. The latent form of the permeability factor derived from skin extracts produced a single immunoprecipitation line with anti-Hageman factor and gave a reaction of identity with a precipitation band developing between purified Hageman factor and anti-Hageman factor. The latent permeability factor in the fraction corrected the clotting activity of Hageman-factor-deficient human plasma. The clotting activity was also blocked by anti-Hageman factor F(ab')2 antibody. From these results, it was concluded that the skin permeability factor was immunologically and functionally indistinguishable from Hageman factor of plasma. Extracts were obtained from skin of guinea pigs given intravenous injections of 125I-guinea pig Hageman factor immediately before sacrifice to calculate the amount of Hageman factor in the extravascular tissue space of the skin. The pseudoglobulin fractions of the extracts containing a concentration of Hageman factor of approximately 9 microgram of Hageman factor per gram of skin. This was determined both by immunologic means and procoagulant activity. Only 4% of the Hageman factor in the extract was obtained from the intravascular plasma volume of the skin. Images Figure 1 PMID:7044129

Yamamoto, T.; Cochrane, C. G.

1982-01-01

213

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

214

Infrared magnetic and negative-index metamaterials  

Microsoft Academic Search

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

Shuang Zhang

2005-01-01

215

Novel additives to retard permeable flow  

SciTech Connect

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

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

2008-09-15

216

Structure/Permeability Relationships Of Polyimide Membranes  

NASA Technical Reports Server (NTRS)

Report describes experimental study of permeabilities, by each of five gases, of membranes made of four different polyimides. Conducted to gain understanding of effects of molecular structures of membranes on permeabilities and to assess potential for exploitation of selective permeability in gas-separation processes. Gases used: H2, O2, N2, CO2, and CH4.

St. Clair, A. K.; Yamamoto, H.; Mi, Y.; Stern, S. A.

1995-01-01

217

STEAM-WATER RELATIVE PERMEABILITY A DISSERTATION  

E-print Network

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

Stanford University

218

Vascular endothelium: a vulnerable transit zone for merciless sodium.  

PubMed

In humans, when plasma sodium concentration rises slightly beyond 140 mM, vascular endothelium sharply stiffens and nitric oxide release declines. In search of a vascular sodium sensor, the endothelial glycocalyx was identified as being a negatively charged biopolymer capable of selectively buffering sodium ions. Sodium excess damages the glycocalyx and renders vascular endothelium increasingly permeable for sodium. In the long term, sodium accumulates in the interstitium and gradually damages the organism. It was discovered that circulating red blood cells (RBC) 'report' surface properties of the vascular endothelium. To some extent, the RBC glycocalyx mirrors the endothelial glycocalyx. A poor (charge-deprived) endothelial glycocalyx causes a poor RBC glycocalyx and vice versa. This observation led to the assumption that the current state of an individual's vascular endothelium in terms of electrical surface charges and sodium-buffering capabilities could be read simply from a blood sample. Recently, a so-called salt blood test was introduced that quantifies the RBC sodium buffer capacity and thus characterizes the endothelial function. The arguments are outlined in this article spanning a bridge from cellular nano-mechanics to clinical application. PMID:24335504

Oberleithner, Hans

2014-02-01

219

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

220

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

E-print Network

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

Ning, Xiuxu

1989-01-01

221

Deformational characteristics of rock in low permeable reservoir and their effect on permeability  

Microsoft Academic Search

In the development of oil and gas the pressure in the rocks of reservoir changes constantly and rocks are compressed and deformed. So their permeability reduces. And the production capacity of oil and gas well is affected by the permeability. This paper deals with the deformational characteristics of rocks in low permeable reservoir and their effect on the permeability. The

Hong-Xing Wang; Guan Wang; Ron C. K. Wong

2010-01-01

222

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

223

Cytotoxicity, permeability, and inflammation of metal oxide nanoparticles in human cardiac microvascular endothelial cells: cytotoxicity, permeability, and inflammation of metal oxide nanoparticles.  

PubMed

Wide applications and extreme potential of metal oxide nanoparticles (NPs) increase occupational and public exposure and may yield extraordinary hazards for human health. Exposure to NPs has a risk for dysfunction of the vascular endothelial cells. The objective of this study was to assess the cytotoxicity of six metal oxide NPs to human cardiac microvascular endothelial cells (HCMECs) in vitro. Metal oxide NPs used in this study included zinc oxide (ZnO), iron(III) oxide (Fe(2)O(3)), iron(II,III) oxide (Fe(3)O(4)), magnesium oxide (MgO), aluminum oxide (Al(2)O(3)), and copper(II) oxide (CuO). The cell viability, membrane leakage of lactate dehydrogenase, intracellular reactive oxygen species, permeability of plasma membrane, and expression of inflammatory markers vascular cell adhesion molecule-1, intercellular adhesion molecule-1, macrophage cationic peptide-1, and interleukin-8 in HCMECs were assessed under controlled and exposed conditions (12-24 h and 0.001-100 ?g/ml of exposure). The results indicated that Fe(2)O(3), Fe(3)O(4), and Al(2)O(3) NPs did not have significant effects on cytotoxicity, permeability, and inflammation response in HCMECs at any of the concentrations tested. ZnO, CuO, and MgO NPs produced the cytotoxicity at the concentration-dependent and time-dependent manner, and elicited the permeability and inflammation response in HCMECs. These results demonstrated that cytotoxicity, permeability, and inflammation in vascular endothelial cells following exposure to metal oxide nanoparticles depended on particle composition, concentration, and exposure time. PMID:21681618

Sun, Jing; Wang, Shaochuang; Zhao, Dong; Hun, Fei Han; Weng, Lei; Liu, Hui

2011-10-01

224

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

225

Drugs and Vascular Dementia  

Microsoft Academic Search

Between 20 and 35% of all dementias are vascular in origin, their etiology is due to cerebrovascular disease and the risk factors are known (e.g. hypertension, diabetes, smoking, or hyperlipidemia). Primary and secondary preventions are the basis of therapeutics. Symptomatic treatment is emerging, notably in the field of cognitive disorders. In that respect, monoamine oxidase inhibitors, and more recently acetylcholinesterase

Hervé Allain; Danièle Bentue-Ferrer; Olivier Tribut; Jean-François Pinel

2003-01-01

226

Vascular air embolism  

PubMed Central

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

Gordy, Stephanie; Rowell, Susan

2013-01-01

227

Imaging chorioretinal vascular disease  

Microsoft Academic Search

Since its first description more than 40 years ago, fluorescein angiography had a crucial role in the diagnosis and management of chorioretinal vascular disorders such as neovascular age-related macular degeneration. Although fluorescein angiography permits visualization of the retinal microcirculation in exquisite detail, visualization of the choroidal circulation is more limited. Moreover, fluorescein angiography provides only minimal information regarding the functional

P A Keane; S R Sadda

2010-01-01

228

Vascular Function in Women with Previous Gestational Diabetes mellitus  

Microsoft Academic Search

It is hypothesised that vascular dysfunction, which characterises type 2 diabetes, may predate development of hyperglycaemia. 17 women with previous gestational diabetes mellitus, and thus at risk of developing type 2 diabetes, were matched with normal controls for body mass index, menstrual phase, smoking, age, blood pressure, and lipid profiles. All had normal glucose tolerance. Tests of microvascular and macrovascular

Michael M. Hannemann; William G. Liddell; Angela C. Shore; Penny M. Clark; John E. Tooke

2002-01-01

229

Extracellular matrix, junctional integrity and matrix metalloproteinase interactions in endothelial permeability regulation*  

PubMed Central

Vascular endothelial permeability is maintained by the regulated apposition of adherens and tight junctional proteins whose organization is controlled by several pharmacological and physiological mediators. Endothelial permeability changes are associated with: (1) the spatial redistribution of surface cadherins and occludin, (2) stabilization of focal adhesive bonds and (3) the progressive activation of matrix metalloproteinases (MMPs). In response to peroxide, histamine and EDTA, endothelial cells sequester VE-cadherin and alter its cytoskeletal binding. Simultaneously, these mediators enhance focal adhesion to the substratum. Oxidants, cytokines and pharmacological mediators also trigger the activation of matrix metalloproteinases (MMPs) in a cytoskeleton and tyrosine phosphorylation dependent manner to degrade occludin, a well-characterized tight junction element. These related in vitro phenomena appear to co-operate during inflammation, to increase endothelial permeability, structurally stabilize cells while also remodelling cell junctions and substratum. PMID:12162724

Alexander, JS; Elrod, John W

2002-01-01

230

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

231

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

SciTech Connect

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

Salman, M.J.

1989-01-01

232

Vascular Dementia: A Radical Redefinition  

Microsoft Academic Search

Vascular dementia’ may be the leading cause of cognitive impairment in the world, yet there is little agreement as to what this concept encompasses or how it is defined. A critical review reaches the conclusion that the concept of ‘vascular dementia’ has become obsolete. ‘Vascular’ is too generic, and fails to identify specific etiologies which may be subject to current

Vladimir Hachinski

1994-01-01

233

Novel Fluorescein Angiography-Based Computer-Aided Algorithm for Assessment of Retinal Vessel Permeability  

PubMed Central

Purpose To present a novel method for quantitative assessment of retinal vessel permeability using a fluorescein angiography-based computer algorithm. Methods Twenty-one subjects (13 with diabetic retinopathy, 8 healthy volunteers) underwent fluorescein angiography (FA). Image pre-processing included removal of non-retinal and noisy images and registration to achieve spatial and temporal pixel-based analysis. Permeability was assessed for each pixel by computing intensity kinetics normalized to arterial values. A linear curve was fitted and the slope value was assigned, color-coded and displayed. The initial FA studies and the computed permeability maps were interpreted in a masked and randomized manner by three experienced ophthalmologists for statistical validation of diagnosis accuracy and efficacy. Results Permeability maps were successfully generated for all subjects. For healthy volunteers permeability values showed a normal distribution with a comparable range between subjects. Based on the mean cumulative histogram for the healthy population a threshold (99.5%) for pathological permeability was determined. Clear differences were found between patients and healthy subjects in the number and spatial distribution of pixels with pathological vascular leakage. The computed maps improved the discrimination between patients and healthy subjects, achieved sensitivity and specificity of 0.974 and 0.833 respectively, and significantly improved the consensus among raters for the localization of pathological regions. Conclusion The new algorithm allows quantification of retinal vessel permeability and provides objective, more sensitive and accurate evaluation than the present subjective clinical diagnosis. Future studies with a larger patients’ cohort and different retinal pathologies are awaited to further validate this new approach and its role in diagnosis and treatment follow-up. Successful evaluation of vasculature permeability may be used for the early diagnosis of brain microvascular pathology and potentially predict associated neurological sequelae. Finally, the algorithm could be implemented for intraoperative evaluation of micovascular integrity in other organs or during animal experiments. PMID:23626701

Chassidim, Yoash; Parmet, Yisrael; Tomkins, Oren; Knyazer, Boris; Friedman, Alon; Levy, Jaime

2013-01-01

234

The Vascular Depression Hypothesis: Mechanisms Linking Vascular Disease with Depression  

PubMed Central

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

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

2013-01-01

235

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

236

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

237

Vascular surgery career resource.  

PubMed

Vascular surgery has undergone a minimally invasive revolution in the past 15 years. The subspecialty emerged with many changes to its training paradigms that have made this field more attractive to both medical student and general surgery resident candidates. Commitment to diagnosis and treatment of arterial, venous, and lymphatic systems disorders remains the cornerstone of this profession, but an entirely new generation of endovascular treatments has been added to the staple of open surgical procedures used to treat these diseases. A wide variety of practice options are available, ranging from high-stress, technologically demanding complex arterial repairs to low-risk, outpatient, venous insufficiency treatment and all combinations in-between. Many online resources are available to allow an interested candidate to stay current with all the exciting changes in the field. This information is maintained by strong national organizations of vascular surgeons. PMID:21266219

Harthun, Nancy L; Gahtan, Vivian

2011-02-01

238

Pathophysiology of vascular dementia  

PubMed Central

The concept of Vascular Dementia (VaD) has been recognized for over a century, but its definition and diagnostic criteria remain unclear. Conventional definitions identify the patients too late, miss subjects with cognitive impairment short of dementia, and emphasize consequences rather than causes, the true bases for treatment and prevention. We should throw out current diagnostic categories and describe cognitive impairment clinically and according to commonly agreed instruments that document the demographic data in a standardized manner and undertake a systematic effort to identify the underlying aetiology in each case. Increased effort should be targeted towards the concept of and criteria for Vascular Cognitive Impairment and Post-Stroke Dementia as well as for genetic factors involved, especially as these categories hold promise for early prevention and treatment. PMID:19895675

2009-01-01

239

Vascular diameter determining the magnification for a microvascular anastomosis.  

PubMed

The purpose of this study was to determine the association between vascular diameters and amount of magnification and to assess the influence of the magnification media on the microanastomosis quality and permeability. Sixty arterial microanostomoses were distributed into three groups: group I (diameter 1.5 mm), group II (1.5 to 2.5 mm), and group III (> 2.5 mm). The models used were carotid artery of Sprague-Dawley rats and carotid and abdominal artery of wild rabbits. In each group, 10 anastomoses were performed with 2.5 x loupes and 10 with 10 x microscope. The total time of anastomosis, the quality of the anastomosis (Gorman scale), and 24-hour permeability rate were measured. The total anastomotic time and quality had statistical differences for the microscope by analyzing the total sample and group I only. The global permeability was 83% for the microscope and 40% for the loupe. The same result was observed in group I but no differences were observed in the other groups. The histology and the survey showed similar results. Microanastomoses performed under a microscope (10 x) were performed in less time, were of better quality, and had higher permeability rates when compared with those performed under a loupe (2.5 x). In vessels < 1.5 mm, these differences were statistically significant but in vessels > 1.5 mm no differences were observed. PMID:18454357

Andrades, Patricio; Benítez, Susana; Danilla, Stefan; Erazo, Cristian; Hasbun, Andrea; Fix, Jobe

2008-04-01

240

Vascular Thoracic Outlet Syndrome  

Microsoft Academic Search

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

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

2003-01-01

241

Fractalkine and vascular injury  

Microsoft Academic Search

The vascular endothelium plays a central role in the recruitment and migration of circulating effector cells into sites of inflammation and immune responses. The unique CX3C-chemokine, fractalkine, is expressed on activated endothelial cells, and its receptor, CX3CR1, is expressed on natural killer cells, monocytes and some CD8+ T cells, all of which possess cytolytic function. Accumulating evidence that fractalkine is

Hisanori Umehara; EdaT Bloom; Toshiro Okazaki; Naochika Domae; Toshio Imai

2001-01-01

242

Aldosterone and Vascular Damage  

Microsoft Academic Search

\\u000a Aldosterone, the final product of the renin-angiotensin-aldosterone system (RAAS), is traditionally viewed as a regulator\\u000a of renal sodium and potassium handling, extracellular volume, and blood pressure (1). Until a few years ago, the adverse vascular effects of the RAAS have been attributed to angiotensin II (Ang II) (2,3). However, Ang II is a potent aldosterone secretagogue, and recent human and

Hylton V. Joffe; Gordon H. Williams; Gail K. Adler

243

Free vascularized fibula grafting  

Microsoft Academic Search

Summary  Eight patients with bone tumor, nonunion of fracture and extensive bony defect were treated by using the technique of free\\u000a vascularized fibula graft. Seven cases were successful and one case failed because of infection. Convalescence was shortened\\u000a significantly. A full description of the operative procedure is presented, with a review of relevant literature and a discussion\\u000a of the historical aspects

Xian Woquan; Hong Guangxiang; Zhu Tongbo

1981-01-01

244

Vascular calcification and magnesium  

Microsoft Academic Search

Pseudoxanthoma elasticum is a rare (1:100,000) autosomalrecessive connective tissue disease caused by a mutation in the gene encoding an ATP-binding cassette transporter, ABCC6. The disease has numerous clinical manifestations, of which perhaps the most important in terms of life expectancy is vascular disease. The patients develop a diffuse arteriopathy secondary to elastic fiber dysgenesis involving the small intramural coronary vessels

Friedrich C. Luft

2010-01-01

245

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

SciTech Connect

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 fractional distributions of radiotracers and were analyzed by a variety of statistical methods which explored the vascular parameters, treatment types, elapsed time, presence of the carcinogen, and histopathologic changes. All treatments resulted in significant changes in vascular volume with time, while only DMBA treatments alone resulted in significant changes in vascular permeability with time. As in prior studies, there were significant vascular volume differences between DMBA and DMBA + radiation groups of tumor-bearing cheek pouches. Radiation significantly affected DMBA-associated vascular volume and permeability changes during carcinogenesis. Several possible explanations for the relationship of these changes to the enhancement of DMBA carcinogenesis are discussed.

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

1985-07-01

246

Numerical simulation of imbibition oil recovery for low permeability fractured reservoir  

Microsoft Academic Search

Based on mechanism of imbibition oil recovery in low permeability fractured reservoir , a mathematical model of dual porosity and dual2permibility imbibition oil recovery is established , and numerical solution method and the acquiring2value method of flow coefficient are presented. Through the verification of practical example , the corresponding water2cut index , which is calculated by this method , meets

YIN Dai; PU Hui; WU Ying

247

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

248

Vascular selectivity of felodipine.  

PubMed

Felodipine, a new antihypertensive 'calcium antagonist', was tested in animal experiments which specifically demonstrated its vascular selectivity. In vitro inorganic and organic calcium antagonists were added cumulatively to the spontaneously active rat portal vein, and the paced papillary muscle of the rat, residing in the same organ bath. Felodipine was the first compound tested to display a 100-fold vascular selectivity in this test system. In the portal vein the spontaneous activity and noradrenaline (norepinephrine)-induced responses are reduced by the drug in therapeutic concentrations in an insurmountable way, indicating that felodipine prevents activation of the vascular effector cells or interferes with the contractile process, possibly due to an intracellular action on Ca2+-binding proteins. The negative myocardial effect of felodipine, attainable only in vitro, is characterised by surmountable antagonism of the inotropic response to added adrenergic agonists or Ca2+ and is compatible with calcium influx inhibition. In vivo, felodipine was given to conscious dogs with indwelling arterial and venous catheters. The animals were studied in the horizontal position and at 45 degrees tilt. Felodipine (1 mumol/kg) and minoxidil (4 mumol/kg) lowered mean arterial blood pressure by 20 to 25%, due to reduced peripheral resistance with a reflex rise in cardiac output. Following head-up tilt (2 min) there was no orthostatic hypotension, and stroke volume was well maintained. This strongly indicates that arterial resistance vessels, but not venous capacitance vessels or myocardium, were directly affected by felodipine. PMID:3987552

Ljung, B

1985-01-01

249

[Vascular erectile dysfunction].  

PubMed

Vascular etiology is present in up to 60% of the patients with erectile dysfunction (ED). Both small vessel disease, such as that in diabetes mellitus, and arteriosclerosis of bigger size arteries, as in hypertension, cause arterial insufficiency and erectile dysfunction. Tobacco smoking alters the arterial hemodynamics in the penis, causing erectile dysfunction in a high percentage of advanced age smokers: pelvic arteries fibrosis and stenosis accelerates the existing arteriosclerosis. Venous occlusive dysfunction may be due to the decrease of corpora cavernosa compliance or tunica albuginea inherent anomalies. Vascular endothelial growth factor may play a role in the modulation of vascularization of the normal penile architecture. Various events, all of them important, may cause erectile dysfunction. Moreover, no cause can participate independently. A cascade of situations (including psychological factors as well as organic) may lead to erectile dysfunction. A continuous understanding of organic causes of erectile dysfunction will allow physicians to discover treatments for their correction, as well as to give confidence to the patient. PMID:20978287

Odriozola, Ander Astobieta; Quintanilla, Mikel Gamarra; Arias, José Gregorio Pereira; Tamayo, Asier Leibar; González, Gaspar Ibarluzea

2010-10-01

250

Immigration Index  

NSDL National Science Digital Library

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

251

Vascular Endothelial growth factor signaling in hypoxia and Inflammation  

PubMed Central

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 reprogramming 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

2014-01-01

252

Glycoconjugates and Related Molecules in Human Vascular Endothelial Cells  

PubMed Central

Vascular endothelial cells (ECs) form the inner lining of blood vessels. They are critically involved in many physiological functions, including control of vasomotor tone, blood cell trafficking, hemostatic balance, permeability, proliferation, survival, and immunity. It is considered that impairment of EC functions leads to the development of vascular diseases. The carbohydrate antigens carried by glycoconjugates (e.g., glycoproteins, glycosphingolipids, and proteoglycans) mainly present on the cell surface serve not only as marker molecules but also as functional molecules. Recent studies have revealed that the carbohydrate composition of the EC surface is critical for these cells to perform their physiological functions. In this paper, we consider the expression and functional roles of endogenous glycoconjugates and related molecules (galectins and glycan-degrading enzymes) in human ECs. PMID:24171112

Toyoda, Masashi

2013-01-01

253

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

SciTech Connect

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

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

1989-02-01

254

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

2015-03-01

255

Vascular Risk Factors and Clinical Progression in Spinocerebellar Ataxias  

PubMed Central

Background The contributions of vascular risk factors to spinocerebellar ataxia (SCA) are not known. Methods We studied 319 participants with SCA 1, 2, 3, and 6 and repeatedly measured clinical severity using the Scale for Assessment and Rating of Ataxia (SARA) for 2 years. Vascular risk factors were summarized by CHA2DS2-VASc scores as the vascular risk factor index. We employed regression models to study the effects of vascular risk factors on ataxia onset and progression after adjusting for age, sex, and pathological CAG repeats. Our secondary analyses took hyperlipidemia into account. Results Nearly 60% of SCA participants were at low vascular risks with CHA2DS2-VASc?=?0, and 31% scored 2 or greater. Higher CHA2DS2-VASc scores were not associated with either earlier onset or faster progression of ataxia. These findings were not altered after accounting for hyperlipidemia. Discussion Vascular risks are not common in SCAs and are not associated with earlier onset or faster ataxia progression. PMID:25713748

Lo, Raymond Y.; Figueroa, Karla P.; Pulst, Stefan M.; Lin, Chi-Ying; Perlman, Susan; Wilmot, George; Gomez, Christopher M.; Schmahmann, Jeremy; Paulson, Henry; Shakkottai, Vikram G.; Ying, Sarah H.; Zesiewicz, Theresa; Bushara, Khalaf; Geschwind, Michael; Xia, Guangbin; Subramony, S. H.; Ashizawa, Tetsuo; Kuo, Sheng-Han

2015-01-01

256

The role of ADAM-mediated shedding in vascular biology.  

PubMed

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

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

2012-01-01

257

Clamshell excavation of a permeable reactive barrier  

Microsoft Academic Search

Nowadays, permeable reactive barriers (PRB) are one of the most widespread techniques for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC in: Permeable reactive barriers: lessons learned\\/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive

Antonio Di Molfetta; Rajandrea Sethi

2006-01-01

258

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

259

Increased mucosal permeability after intestinal ischemia-reperfusion injury is mediated by local tissue factors.  

PubMed

Subclinical intestinal ischemia-reperfusion injury (IRI) causes an increase in mucosal permeability and may represent an early event in the pathogenesis of necrotizing enterocolitis. The present study was undertaken to determine whether these changes are mediated by local or systemic factors. In 6-week-old weanling rats, the ileum was divided into two isolated loops with separate vascular supplies. The mesentery of the proximal loop was occluded for 30 minutes, following which the bowel was reperfused; permeability to 51Cr EDTA was then assessed in the distal loop 30 minutes after reperfusion. In control groups, the distal loop was subjected to 30-minute IRI ("positive" control) or 30-minute sham operation ("negative" control). Permeability in the distal loop was increased only with IRI to the distal bowel (15.4 +/- 3 counts/min/standard), and not with IRI to the proximal bowel (5.1 +/- 1) or with sham operation (8.5 +/- 2). To determine whether a mild "priming" injury might be necessary for systemic factors to have an effect, the distal loop was subjected to 2-minute IRI and the proximal to 30-minute IRI or sham. Permeability was not increased in the distal loop in either of these groups (5.7 +/- 1 and 7.8 +/- 2, respectively). Thirty-minute IRI in the proximal loop did not increase permeability in the distal loop, with or without a priming injury. Only direct IRI in the distal loop resulted in a significant increase in permeability. We conclude that the permeability changes in this model are mediated through local tissue effects, rather than by systemic factors. PMID:1501006

Langer, J C; Sohal, S S

1992-03-01

260

Insulin increases glomerular filtration barrier permeability through dimerization of protein kinase G type I? subunits.  

PubMed

The increase in the permeability of the glomerular barrier filtration to albumin is a well-known feature of diabetic microvasculature and a negative prognostic factor for vascular complications. However, the underlying mechanisms are incompletely understood. We demonstrated recently that superoxide anion generation increases dimerization of protein kinase G type I? (PKGI?) subunits, leading to podocyte dysfunction. Here we investigated whether high insulin concentration is involved in PKGI-dependent hyperpermeability of the diabetic glomerular filtration barrier. We assessed changes in insulin-induced glomerular permeability by measuring glomerular capillary permeability to albumin in isolated glomeruli from Wistar and obese and lean Zucker rats and transmembrane albumin flux in cultured rat podocytes. Expression of PKGI? and upstream proteins was confirmed in the podocytes using Western blotting and immunofluorescence. Insulin (300nM, 5min) increased NAD(P)H-dependent glomerular albumin permeability in Wistar rats and PKGI-dependent transmembrane albumin flux in cultured podocytes. Podocyte exposure to insulin in non-reducing conditions increased PKGI? interprotein disulfide bond formation, altered the phosphorylation of the PKG target proteins MYPT1 and MLC, and disrupted the actin cytoskeleton. The role of NADPH oxidase (NOX) in insulin-induced reactive oxygen species (ROS) generation and insulin-evoked increases in albumin permeability in podocytes was confirmed with NOX2 and NOX4 siRNA. Glomerular albumin permeability was increased in hyperinsulinemic Zucker obese rats with isolated glomeruli showing increased expression of PKGI? and NOX4. Taken together, these data demonstrate that insulin increases glomerular barrier albumin permeability via a PKGI-dependent mechanism involving NAD(P)H-dependent generation of superoxide anion. These findings reveal a role for insulin in the pathophysiology of diabetic glomerular nephropathy. PMID:23454089

Piwkowska, Agnieszka; Rogacka, Dorota; Kasztan, Ma?gorzata; Angielski, Stefan; Jankowski, Maciej

2013-06-01

261

Inflammation and Vascular Injury  

PubMed Central

The invited special lecture at the 76th Annual Scientific Meeting of the Japanese Circulation Society focused on the central role of inflammation in vascular injury and repair. Early studies pioneered the concept that mechanical injury, such as balloon angioplasty and endovascular stent deployment, elicits an inflammatory response from the vessel wall. This hypothesis was developed and substantiated at a time when the prevailing dogma viewed restenosis following angioplasty as a primarily proliferative smooth muscle cell disease. Antibody targeting of Mac-1 reduced leukocyte accumulation and limited neointimal formation following balloon injury or stent implantation. Genetic absence of Mac-1 resulted in diminished leukocyte accumulation and neointimal thickening after carotid artery injury in mice. In the course of those studies, our laboratory made fundamental discoveries regarding the mechanism of leukocyte recruitment at sites of vascular injury and identified platelet glycoprotein (GP) Ib?, a component of the GPIb-IX-V complex, as the previously unknown platelet counter-receptor for Mac-1. Follow-on studies have focused extensively on the structure, function, and signaling of the leukocyte integrin Mac-1. The binding site for GPIb? in Mac-1 has been mapped and subsequently showed that leukocyte engagement of platelet GPIb? via Mac-1 is critical not only for the biological response to vascular injury, but also for thrombosis, vasculitis, glomerulonephritis, and multiple sclerosis, thereby advancing the hypothesis that virtually all inflammation is platelet-dependent. Furthermore, ligand engagement of Mac-1 initiates a novel gene program that promotes inflammation by activating NF?B and downregulating the expression of the forkhead transcription factor Foxp1 that controls monocyte differentiation. Small molecule inhibitors of Mac-1 function have been pursued, including targeting of Mac-1-GPIb? binding or the downstream tyrosine kinase spleen tyrosine kinase. Drs Teruo Inoue, Koichi Node, Tatsuya Fukotomi, Masashi Sakuma, Toshifumi Morooka, and Kohsuke Nakajima, valued Japanese collaborators and post-doctoral fellows, have contributed enormously to these discoveries. PMID:22785436

Simon, Daniel I.

2014-01-01

262

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

263

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

264

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

265

Lossy gradient index metamaterial with sinusoidal periodicity of refractive index: case of constant impedance throughout the structure  

NASA Astrophysics Data System (ADS)

We used an exact analytical approach to investigate the electromagnetic wave propagation across an isotropic metamaterial composite with i. a sinusoidally periodic gradient of the real parts of the effective permittivity and permeability, ii. spatially uniform imaginary parts of the effective permittivity and permeability, and iii. spatially uniform impedance. The real part of the effective refractive index can be positive and negative along the direction of nonhomogeneity. A remarkably simple direct solution for the field distribution was obtained.

Dalarsson, Mariana; Norgren, Martin; Jakši?, Zoran

2011-01-01

266

Head and neck vascular lesions.  

PubMed

Vascular lesions of the head and neck are complex and diverse. These include infantile hemangioma, venous malformations, lymphatic malformations, and arteriovenous malformations, among others. Vascular malformations and tumors display different growth patterns and require different approaches to treatment. Therefore, accurate diagnosis is of utmost importance. This article is a guide for the diagnosis and management of vascular lesions of the head and neck. PMID:25439548

Hoff, Stephen R; Rastatter, Jeffrey C; Richter, Gresham T

2015-02-01

267

The Effect of Stress and Pore Pressure on Formation Permeability of Ultra-Low-Permeability Reservoir  

Microsoft Academic Search

Low-permeability reservoirs have attracted increased attention from most oil companies due to increased demand and limited reserves in conventional reservoirs. Most scholars agree that worldwide hydrocarbon production decline from conventional reservoirs will be compensated for by the development of low-permeability reservoirs to satisfy growing demand. During the production life cycle of a low-permeability reservoir, permeability at any given location may

F. Ma; S. He; H. Zhu; Q. Xie; C. Jiao

2012-01-01

268

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

269

Rib index.  

PubMed

This article analyzes the double rib contour sign (DRCS) and the rib index (RI). The analyzed topics are 1. the history of presentations - publication of DRCS-RI, 2. the study source origin: school screening for idiopathic scoliosis (IS), 3. what the DRCS and the RI are- Description, 4. the quantification of the DRCS - RI, 5. a reliability study for RI 6. how much the rib index is affected by the distance between the radiation source and the irradiated individual, 7. the implications on IS aetiology, 8. the applications of Rib index for a. documentation of the deformity, b. assessment of physiotherapy, c. assessment of brace treatment and d. pre- and post-operative assessment; assessment of the rib-cage deformity correction on the transverse plane, 9. the use of RI and implications for screening policies 10. the reference of the RI method in spinal textbooks and finally 11. the citations in Google Scholar. PMID:25635184

Grivas, Theodoros B

2014-01-01

270

RhoA and ROCK mediate histamine-induced vascular leakage and anaphylactic shock.  

PubMed

Histamine-induced vascular leakage is an integral component of many highly prevalent human diseases, including allergies, asthma and anaphylaxis. Yet, how histamine induces the disruption of the endothelial barrier is not well defined. By using genetically modified animal models, pharmacologic inhibitors and a synthetic biology approach, here we show that the small GTPase RhoA mediates histamine-induced vascular leakage. Histamine causes the rapid formation of focal adherens junctions, disrupting the endothelial barrier by acting on H1R G?q-coupled receptors, which is blunted in endothelial G?q/11 KO mice. Interfering with RhoA and ROCK function abolishes endothelial permeability, while phospholipase C? plays a limited role. Moreover, endothelial-specific RhoA gene deletion prevents vascular leakage and passive cutaneous anaphylaxis in vivo, and ROCK inhibitors protect from lethal systemic anaphylaxis. This study supports a key role for the RhoA signalling circuitry in vascular permeability, thereby identifying novel pharmacological targets for many human diseases characterized by aberrant vascular leakage. PMID:25857352

Mikelis, Constantinos M; Simaan, May; Ando, Koji; Fukuhara, Shigetomo; Sakurai, Atsuko; Amornphimoltham, Panomwat; Masedunskas, Andrius; Weigert, Roberto; Chavakis, Triantafyllos; Adams, Ralf H; Offermanns, Stefan; Mochizuki, Naoki; Zheng, Yi; Gutkind, J Silvio

2015-01-01

271

Role of vascular endothelial growth factor in diabetic vascular complications  

Microsoft Academic Search

Role of vascular endothelial growth factor in diabetic vascular complicationsBackgroundMuch of the morbidity and mortality associated with diabetes mellitus predominantly reflects its deleterious effects on microcirculation and macrocirculation. During the past few years, rapid advancement has been made in our understanding of the mechanisms and molecules involved in the pathogenesis of diabetic microvasculopathy. This is particularly true with regard to

Lloyd Paul Aiello; Jun-Shyan Wong

2000-01-01

272

Flow Characteristics in Permeable Reactive Barrier Affected by Biological Clogging  

Microsoft Academic Search

Permeable reactive barriers (PRB) are becoming popular for the in situ remediation of contaminated groundwater. The efficiency of the PRB is affected by permeability of the reactive zone, because when permeability decreases contaminants can bypass the reactive zone without degraded. One of the factors affecting permeability of the permeable reactive zone is biological clogging of soil pore, i.e., biomass buildup

K. Seki; J. Hanada; T. Miyazaki

2004-01-01

273

Changes in permeability of the alveolar-capillary barrier in firefighters.  

PubMed

The effect on alveolar-capillary barrier permeability of chronic exposure to a smoke produced by the partial combusion of diesel oil, paraffin, and wood was examined. An index of permeability was determined from the rate of transfer from the lung into the blood of the hydrophilic, labelled chelate 99mTc diethylene triamine penta-acetate (MW 492 dalton). The results of this test were expressed as the half time clearance of the tracer from the lung into the blood (T1/2 LB). The study was carried out at the Royal Naval Firefighting School, HMS Excellent. Permeability index was measured on seven non-smoking naval firefighting instructors who had worked at the school for periods of longer than two and a half months. Tests of airway function and carbon monoxide transfer factor were performed on four of these seven instructors. The results of the permeability index showed a T1/2 LB of 26 min +/- 5 (SEM) which differed significantly from that of normal non-smokers. By contrast all other lung function tests had values within the predicted normal range. PMID:3899161

Minty, B D; Royston, D; Jones, J G; Smith, D J; Searing, C S; Beeley, M

1985-09-01

274

Borosilicate films as permeability barriers  

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

275

219 vascular fellows' perception of the future of vascular surgery.  

PubMed

In an attempt to identify the fellows' concerns about the future of the field of vascular surgery, we conducted a survey consisting of 22 questions at an annual national meeting in March from 2004 to 2007. In order to obtain accurate data, all surveys were kept anonymous. The fellows were asked (1) what type of practice they anticipated they would be in, (2) what the new training paradigm for fellows should be, (3) to assess their expectation of the needed manpower with respect to the demand for vascular surgeons, (4) what were major threats to the future of vascular surgery, (5) whether they had heard of and were in favor of the American Board of Vascular Surgery (ABVS), (6) who should be able to obtain vascular privileges, and (7) about their interest in an association for vascular surgical trainees. Of 273 attendees, 219 (80%) completed the survey. Males made up 87% of those surveyed, and 60% were between the ages of 31 and 35 years. Second-year fellows made up 82% of those surveyed. Those expecting to join a private, academic, or mixed practice made up 35%, 28%, and 20% of the respondents, respectively, with 71% anticipating entering a 100% vascular practice. Forty percent felt that 5 years of general surgery with 2 years of vascular surgery should be the training paradigm, while 45% suggested 3 and 3 years, respectively. A majority, 79%, felt that future demand would exceed the available manpower, while 17% suggested that manpower would meet demand. The major challenges to the future of vascular surgery were felt to be competition from cardiology (82%) or radiology (30%) and lack of an independent board (29%). Seventeen percent were not aware of the ABVS, and only 2% were against it; 71% suggested that vascular privileges be restricted to board-certified vascular surgeons. Seventy-six percent were interested in forming an association for vascular trainees to address the issues of the future job market (67%), endovascular training during fellowship (56%), increasing focus on the vascular fellows at national meetings (49%), and representation for the fellows on the national councils (37%). This survey suggests that several significant issues exist in the minds of vascular trainees that have not been addressed and may present opportunities for further dialogue. PMID:18973989

Hingorani, Anil P; Ascher, Enrico; Marks, Natalie; Shiferson, Alexander; Puggioni, Alessandra; Tran, Victor; Patel, Nirav; Jacob, Theresa

2009-01-01

276

Permeability of single nuclear pores.  

PubMed Central

In this first application of optical single transporter recording (OSTR), a recently established technique for optically monitoring the activity of single transporters in membrane patches (Tschödrich-Rotter and Peters. 1998. J. Microsc. 192:114-125), the passive permeability of the nuclear pore complex (NPC) was measured for a homologous series of hydrophilic probe molecules. Nuclei were isolated from Xenopus oocytes and firmly attached to filters containing small cylindrical pores. Transport through membrane patches spanning filter pores was measured by scanning microphotolysis. Thus the permeability coefficients of single NPCs were determined for fluorescently labeled dextrans of approximately 4, 10, and 20 kDa. Dextrans of >/=40 kDa could not permeate the NPC. The data were consistent with a model in which the NPC contains a single diffusion channel. By application of established theories for the restricted diffusion through small pores, the diffusion channel was approximated as a cylinder with a radius of 4.4-6.1 nm (mean 5. 35 nm). Because the transport rate constant of the single NPC was known, the equivalent length of the channel could be also determined and was found to be 40-50 nm (mean 44.5 nm). The symmetry of the NPC implies that a singular component such as the diffusion channel is located at the center of the NPC. Therefore a common transport pathway apparently mediates both passive and signal-dependent transport. To test this hypothesis, measurements of signal-dependent transport and of the mutual effects signal-dependent and passive transport may exert on each other are in progress. PMID:10388751

Keminer, O; Peters, R

1999-01-01

277

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.

Jennifer Doherty

278

Permeability of a fracture with cylindrical asperities  

Microsoft Academic Search

The permeability of a rock fracture that is modeled as two smooth, parallel faces propped open by randomly located, uniformly sized cyclindrical asperities, is investigated. The viscous resistance due to the asperities is accounted for by an in-plane permeability coefficient, and a Brinkman-type equation is used to find the velocity distribution across the thickness of the fracture. The resulting simple

Sunil Kumar; Robert W. Zimmerman; Gudmundur S. Bodvarsson

1991-01-01

279

Spontaneous Imbibition in Low Permeability Carbonates  

Microsoft Academic Search

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

Can Ulas Hatiboglu; Ugur Karaaslan; Serhat Akin

2005-01-01

280

Effect of Dead Algae on Soil Permeability  

SciTech Connect

Since existing basins support heavy growths of unicellular green algae which may be killed by temperature variation or by inadvertent pH changes in waste and then deposited on the basin floor, information on the effects of dead algae on soil permeability was needed. This study was designed to show the effects of successive algal kills on the permeability of laboratory soil columns.

Harvey, R.S.

2003-02-21

281

A method of determination of permeability  

SciTech Connect

A method is proposed for determining permeability of coals under conditions of steady-state deformation and stationary filtration mode by employing a reference core made of gas-non-sorbing material with a known permeability. The approach has been developed to assess the time of transition to the stable filtration.

Kuznetsov, S.V.; Trofimov, V.A. [Russian Academy of Sciences, Moscow (Russian Federation)

2007-11-15

282

Influence of fiber packing structure on permeability  

NASA Technical Reports Server (NTRS)

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

Cai, Zhong; Berdichevsky, Alexander L.

1993-01-01

283

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

284

Internet based vascular risk factor management for patients with clinically manifest vascular disease: randomised controlled trial  

PubMed Central

Objective To investigate whether an internet based, nurse led vascular risk factor management programme promoting self management on top of usual care is more effective than usual care alone in reducing vascular risk factors in patients with clinically manifest vascular disease. Design Prospective randomised controlled trial. Setting Multicentre trial in secondary and tertiary healthcare setting. Participants 330 patients with a recent clinical manifestation of atherosclerosis in the coronary, cerebral, or peripheral arteries and with at least two treatable risk factors not at goal. Intervention Personalised website with an overview and actual status of patients’ risk factors and mail communication via the website with a nurse practitioner for 12 months; the intervention combined self management support, monitoring of disease control, and drug treatment. Main outcome measures The primary endpoint was the relative change in Framingham heart risk score after 1 year. Secondary endpoints were absolute changes in the levels of risk factors and the differences between groups in the change in proportion of patients reaching treatment goals for each risk factor. Results Participants’ mean age was 59.9 (SD 8.4) years, and most patients (n=246; 75%) were male. After 1 year, the relative change in Framingham heart risk score of the intervention group compared with the usual care group was ?14% (95% confidence interval ?25% to ?2%). At baseline, the Framingham heart risk score was higher in the intervention group than in the usual care group (16.1 (SD 10.6) v 14.0 (10.5)), so the outcome was adjusted for the separate variables of the Framingham heart risk score and for the baseline Framingham heart risk score. This produced a relative change of ?12% (?22% to ?3%) in Framingham heart risk score for the intervention group compared with the usual care group adjusted for the separate variables of the score and ?8% (?18% to 2%) adjusted for the baseline score. Of the individual risk factors, a difference between groups was observed in low density lipoprotein cholesterol (?0.3, ?0.5 to ?0.1, mmol/L) and smoking (?7.7%, ?14.9% to ?0.4%). Some other risk factors tended to improve (body mass index, triglycerides, systolic blood pressure, renal function) or tended to worsen (glucose concentration, albuminuria). Conclusion An internet based, nurse led treatment programme on top of usual care for vascular risk factors had a small effect on lowering vascular risk and on lowering of some vascular risk factors in patients with vascular disease. Trial registration Clinical trials NCT00785031. PMID:22692651

2012-01-01

285

Location and size of carotid body-like organs (paraganglia) revealed in rats by the permeability of blood vessels to Evans blue dye  

Microsoft Academic Search

Summary We determined the number, distribution, size, and morphology of paraganglia near the glossopharyngeal, vagus, and sympathetic nerves of rats. The location of paraganglia was revealed by a method that takes advantage of the comparatively high permeability of their blood vessels to Evans blue dye. Rats were fixed by vascular perfusion of glutaraldehyde 2 min after receiving an intravenous injection

Donald M. McDonald; Richard W. Blewett

1981-01-01

286

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

287

Kinin receptors in vascular biology and pathology.  

PubMed

Endogenous kinins are important vasoactive peptides whose effects are mediated by two G-Protein-coupled receptors (R), named B2R (constitutive) and B1R (inducible). They are involved in vascular homeostasis, ischemic pre- and post- conditioning, but also in cardiovascular diseases. They contribute to the therapeutic effects of angiotensin-1 converting enzyme inhibitors (ACEI) and angiotensin AT1 receptor blockers. Benefits derive primarily from vasodilatory, antiproliferative, antihypertrophic, antifibrotic, antithrombic and antioxidant properties, which are associated with the release of endothelial factors such as nitric oxide, prostacyclin and tissue plasminogen activator. Uncontrolled production of kinins or the inhibition of their metabolism may lead to unwanted pro-inflammatory side effects. Thus, B2R antagonism is salutary in angioedema, septic shock, stroke, and Chagas vasculopathy. B1R is virtually absent in healthy tissues, yet this receptor is induced by the cytokine pathway and the oxidative stress via the transcriptional nuclear factor NF-?B. The B1R may play a compensatory role for the lack of B2R, and its up-regulation during tissue damage may be a useful mechanism of host defense. Activation of both receptors may be beneficial, notably in neovascularisation, angiogenesis, heart ischemia and diabetic nephropathy. At the same time, B1R is a potent activator of inducible nitric oxide and NADPH oxidase, which are associated with vascular inflammation, increased permeability, insulin resistance, endothelial dysfunction and diabetic complications. The dual beneficial and deleterious effects of kinin receptors and, particularly B1R, raise an unsettled issue on the therapeutic value of B1R/B2R agonists versus antagonists in cardiovascular diseases. Hence, the Janus-face of kinin receptors needs to be seriously addressed in the upcoming clinical trials for each pathological setting. PMID:24568157

Couture, Rejean; Blaes, Nelly; Girolami, Jean-Pierre

2014-03-01

288

Vascular factors and epigenetic modifications in the pathogenesis of Alzheimer's disease.  

PubMed

Alzheimer's disease (AD) is a debilitating illness with no known cure. Nowadays accumulating evidence suggested that the vascular endothelium and chronic hypoperfusion may play important role in pathobiology of AD. The vascular endothelium which regulates the passage of macromolecules and circulating cells from blood to tissue, is a major target of oxidative stress, playing a critical role in the pathophysiology of vascular diseases. Since the vascular endothelium, neurons and glia are all able to synthesize, store and release reactive oxygen species (ROS) and vascular active substances in response to certain stimuli, their contribution to the pathophysiology of AD can be very important. New evidence indicates that continuous formation of free ROS induces cellular damage and decreases antioxidant defenses. Specifically, oxidative stress increases vascular endothelial permeability and promotes leukocyte adhesion. We summarize the reports that sporadic, late-onset of AD results from vascular etiology. Recently an involvement of epigenetic alterations in the etiology of AD is also intensively investigated. Gaining a more complete understanding of the essential components and underlying mechanisms involved in epigenetic regulation could lead to novel treatments for a number of neurological and psychiatric conditions. PMID:23026534

Leszek, Jerzy; Sochocka, Marta; G?siorowski, Kazimierz

2012-12-15

289

Infrared magnetic and negative-index metamaterials  

NASA Astrophysics Data System (ADS)

Negative-index materials have attracted much attention because of their many unconventional optical properties such as negative refractive angle, phase back propagation, reversed Doppler effect and reversed Cherenkov radiation. Recently, much progress has been made in this research area such as demonstrations of negative permeability "metamaterials" in the rf and microwave regimes, and the predictions and demonstrations (largely in the rf) of negative index materials (and predictions of diffraction-less "perfect" imaging in these materials). In this dissertation, fabrication and characterization of several novel metal-based metamaterial that show unconventional IR/optical properties are discussed. While metals provide a negative permittivity at frequencies below the plasma frequency, naturally occurring materials with negative permeability at optical frequencies are not available. Composite electromagnetic materials with resonant structures with sizes much less than the wavelength can act as an effective homogeneous media with a negative permeability. One widely used structure to achieve negative permeability in rf is the so called "split ring resonator" (SRR) proposed by Pendry. By using SRR, the highest resonant frequency that has been obtained is around 1 THz. The complexity of SRR makes it difficult to be further scaled down to reach magnetic resonance at infrared frequencies, even with electron beam lithography. As part of this dissertation, the fabrication, characterization and modeling of arrays of a new nanostructure design with resonances in the mid-IR region and properties that demonstrate strong magnetic activity indicative of negative permeability are described. This is the first experimental work on negative permeability reported in the mid-IR. In addition, interferometric lithography (IL) combined with self-aligned semiconductor processing techniques were used for the fabrication, leading to large area samples with good uniformity. By combining structures with magnetic response and electrical response, a negative refractive index metamaterial is designed and fabricated using IL. The refractive index of the fabricated structure is obtained uniquely from the experimental results by measuring both the amplitude and phase of the transmission and reflectance. This is the first demonstration of negative index metamaterials in the near-IR, about 4 orders of magnitude shorter than previously reported work. Furthermore, parametric studies and experimental results show that better design with very low loss can be achieved, which might lead to more useful applications.

Zhang, Shuang

290

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

291

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/

292

Assessment of Cardiovascular Disease Using Permeability Rates: Quantification by Optical Coherence Tomography  

NASA Astrophysics Data System (ADS)

In order to prevent major damage to the cardiovascular system, it is of vital importance to monitor molecular changes in vascular tissues. Symptoms of cardiovascular diseases frequently do not manifest themselves until it is too late for effective treatment; therefore, methodologies that facilitate early detection are crucial. Atherosclerosis is a major underlying cause of many cardiovascular diseases; thus, elucidating the mechanisms of atherosclerosis is essential for shedding light on the initiation and progression of atherosclerotic lesions. Atherosclerosis includes an inflammatory process in arterial tissue that involves subintimal accumulation of lipoproteins particles, mainly low-density lipoprotein and lipoprotein[a]. Measurement of the permeation rates of these particles should extend our understanding of this disease and lead to methods for early disease detection. Over the past decade, optical coherence tomography (OCT) has become widely used in research and, more recently, has been used as a high-resolution imaging technique, capable of quantifying molecular permeability in biological tissues. OCT enables highly sensitive and accurate measurement of permeability rates of molecules and particles in vascular tissue. This sensitivity is due to high in-depth and transverse resolution along with a high dynamic range. In this chapter, we discuss the permeation of molecules and particles through human and animal vascular tissue.

Ghosn, Mohamad G.; Mashiatulla, Maleeha; Morrisett, Joel D.; Larin, Kirill V.

293

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

294

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.

295

Vascular access for hemodialysis.  

PubMed

Indwelling central venous catheters were consecutively used as access for acute and chronic hemodialysis, emergency treatment of pulmonary fluid overload, intoxication and electrolyte disturbances, plasmapheresis, and semiacute continuous dialysis strategies, such as continuous arteriovenous hemofiltration (CAVH). Modification in catheter structure also made it possible to use this access for long-term treatment (e.g., surgically insertable catheters [Hickman], soft large-bore catheters for blind insertion). We discuss the remaining open questions in this field: Which is the insertion site of preference (i.e., subclavian, femoral, or deep jugular)? Should we prefer stiff or soft catheters? Should soft catheters be positioned surgically or is blind insertion by nonsurgeons as adequate? Is it necessary to couple catheter insertion to adjuvant techniques, such as echographic guidance, to reduce complications? Is the currently used polymer structure of the catheters acceptable? Should catheter dialysis be used with single or double vascular access? PMID:8024472

Vanholder, R; Ringoir, S

1994-04-01

296

Avian vascular imaging: a review.  

PubMed

Vascular diseases in birds are not uncommon, according to findings from postmortem surveys. Although atherosclerosis affecting psittacine birds appears overrepresented, some degenerative, infectious, neoplastic, and congenital vascular diseases may also occur. A variety of imaging diagnostic tools may be used to evaluate the avian vascular system, such as conventional radiography, fluoroscopy, rigid endoscopy, computed tomography, angiography, transcoelomic, and transesophageal ultrasound examination. The wide array of current diagnostic imaging tools offers the clinician capabilities to investigate avian cardiovascular abnormalities. Further research in this domain and constant efforts to apply several, and newer, vascular imaging modalities in clinical cases are needed to expand our avian cardiovascular knowledge base. The ability to diagnose vascular pathologic processes in small avian patients may be improved by recent developments in diagnostic imaging technology. PMID:21046937

Beaufrère, Hugues; Pariaut, Romain; Rodriguez, Daniel; Tully, Thomas N

2010-09-01

297

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

298

Caffeine's Vascular Mechanisms of Action.  

PubMed

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

299

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

300

21 CFR 886.5916 - Rigid gas permeable contact lens.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916...Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to...

2012-04-01

301

Field Demonstration Of Permeable Reactive Barriers To Remove  

E-print Network

Field Demonstration Of Permeable Reactive Barriers To Remove Dissolved Uranium From Groundwater-001 November 2000 FIELD DEMONSTRATION OF PERMEABLE REACTIVE BARRIERS TO REMOVE DISSOLVED URANIUM FROM ACKNOWLEDGEMENTS The Project Officer of the Fry Canyon Permeable Reactive Barrier Demonstration Project, Ed

302

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

PubMed Central

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

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

2013-01-01

303

Ionic Mechanisms of Peptide-Induced Responses in Vascular Endothelial Cells  

Microsoft Academic Search

\\u000a The single layer of endothelial cells (ECs) that lines the luminal side of blood vessels plays an important role in regulating\\u000a blood vessel function. Underlying the EC layer are several layers of vascular smooth muscle cells (VSMC) (Fig. 1). Although\\u000a the EC layer serves in part as a protective covering and permeability barrier to the movement of substances through the

Jianben Song; Jeffrey L. Ram

304

The non-excitable smooth muscle: Calcium signaling and phenotypic switching during vascular disease  

Microsoft Academic Search

Calcium (Ca2+) is a highly versatile second messenger that controls vascular smooth muscle cell (VSMC) contraction, proliferation, and\\u000a migration. By means of Ca2+ permeable channels, Ca2+ pumps and channels conducting other ions such as potassium and chloride, VSMC keep intracellular Ca2+ levels under tight control. In healthy quiescent contractile VSMC, two important components of the Ca2+ signaling pathways that regulate

Suzanne J. House; Marie Potier; Jonathan Bisaillon; Harold A. Singer; Mohamed Trebak

2008-01-01

305

Fluid permeability of deformable fracture networks  

SciTech Connect

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

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

1997-04-01

306

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

307

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

308

Education Index  

NSDL National Science Digital Library

The Education Index Web site provides a guide to "the most useful education-related sites on the Web." The links can be browsed by subject such as astronomy, chemistry, geology, and physics (among many others), or by lifestage, from prenatal and infant all the way to college and continuing education. Although the sites described do not have a date of review or rating system, users should still find the resource worthwhile.

309

Vascular risk and A? interact to reduce cortical thickness in AD vulnerable brain regions  

PubMed Central

Objective: The objective of this study was to define whether vascular risk factors interact with ?-amyloid (A?) in producing changes in brain structure that could underlie the increased risk of Alzheimer disease (AD). Methods: Sixty-six cognitively normal and mildly impaired older individuals with a wide range of vascular risk factors were included in this study. The presence of A? was assessed using [11C]Pittsburgh compound B–PET imaging, and cortical thickness was measured using 3-tesla MRI. Vascular risk was measured with the Framingham Coronary Risk Profile Index. Results: Individuals with high levels of vascular risk factors have thinner frontotemporal cortex independent of A?. These frontotemporal regions are also affected in individuals with A? deposition, but the latter show additional thinning in parietal cortices. A? and vascular risk were found to interact in posterior (especially in parietal) brain regions, where A? has its greatest effect. In this way, the negative effect of A? in posterior regions is increased by the presence of vascular risk. Conclusion: A? and vascular risk interact to enhance cortical thinning in posterior brain regions that are particularly vulnerable to AD. These findings give insight concerning the mechanisms whereby vascular risk increases the likelihood of developing AD and supports the therapeutic intervention of controlling vascular risk for the prevention of AD. PMID:24907234

Reed, Bruce R.; Madison, Cindee M.; Wirth, Miranka; Marchant, Natalie L.; Kriger, Stephen; Mack, Wendy J.; Sanossian, Nerses; DeCarli, Charles; Chui, Helena C.; Weiner, Michael W.; Jagust, William J.

2014-01-01

310

[The future of vascular medicine].  

PubMed

In the future vascular medicine will still have a great impact on health of people. It should be noted that the aging of the population does not lead to a dramatic increase in patient numbers, but will be associated with a changing spectrum of co-morbidities. In addition, vascular medical research has to include the intensive care special features of vascular patients, the involvement of vascular medicine in a holistic concept of fast-track surgery, a geriatric-oriented intensive monitoring and early geriatric rehabilitation. For the future acceptance of vascular medicine as a separate subject area under delimitation of cardiology and radiology is important. On the other hand, the subject is so complex and will become more complex in future specialisations that mixing of surgery and angiology is desirable, with the aim to preserve the vascular surgical knowledge and skills on par with the medical and interventional measures and further develop them. Only large, interdisciplinary guided vascular centres will be able to provide timely diagnosis and therapy, to deal with the growing multi-morbidity of the patient, to perform complex therapies even in an acute emergency and due to sufficient number of cases to present with well-trained and experienced teams. These requirements are mandatory to decrease patients' mortality step by step. PMID:25313887

Kroeger, K; Luther, B

2014-10-01

311

C-type natriuretic peptide modulates permeability of the blood-brain barrier.  

PubMed

C-type natriuretic peptide (CNP) is abundant in brain and is reported to exert autocrine function in vascular cells, but its effect on blood-brain barrier (BBB) permeability has not been clarified yet. Here, we examined this effect. Transendothelial electrical resistance (TEER) of in vitro BBB model, composed of bovine brain microvascular endothelial cells and astrocytes, was significantly dose dependently decreased by CNP (1, 10, and 100 nmol/L). C-type natriuretic peptide treatment reduced both the messenger RNA (mRNA) and protein expressions of tight junction (TJ) protein zonula occludens-1 (ZO-1). The effects on TEER, mRNA, and protein expressions of ZO-1 were mimicked by cyclic GMP (cGMP) analog 8-bromo-cGMP (1 ?mol/L) and reversed by protein kinase G (PKG) inhibitor Rp-8-CPT-cGMPS (100 ?mol/L), thus implying the role of PKG and cGMP signaling in BBB function. Transcription factor JunD knockdown by small interfering RNA resulted in no change of permeability by CNP. In vivo study of mouse brain by fluorimetric analysis with intravenous administration of sodium fluorescein (40 mg/kg) also showed a significant increase in BBB permeability by CNP (10 nmol/kg, intravenously). These findings suggest that CNP modulates the BBB permeability by altering ZO-1 expression. PMID:24398935

Bohara, Manoj; Kambe, Yuki; Nagayama, Tetsuya; Tokimura, Hiroshi; Arita, Kazunori; Miyata, Atsuro

2014-04-01

312

Gas Permeable Chemochromic Compositions for Hydrogen Sensing  

NASA Technical Reports Server (NTRS)

A (H2) sensor composition includes a gas permeable matrix material intermixed and encapsulating at least one chemochromic pigment. The chemochromic pigment produces a detectable change in color of the overall sensor composition in the presence of H2 gas. The matrix material provides high H2 permeability, which permits fast permeation of H2 gas. In one embodiment, the chemochromic pigment comprises PdO/TiO2. The sensor can be embodied as a two layer structure with the gas permeable matrix material intermixed with the chemochromic pigment in one layer and a second layer which provides a support or overcoat layer.

Bokerman, Gary (Inventor); Mohajeri, Nahid (Inventor); Muradov, Nazim (Inventor); Tabatabaie-Raissi, Ali (Inventor)

2013-01-01

313

Nanomedicine for drug targeting: strategies beyond the enhanced permeability and retention effect  

PubMed Central

The growing research interest in nanomedicine for the treatment of cancer and inflammatory-related pathologies is yielding encouraging results. Unfortunately, enthusiasm is tempered by the limited specificity of the enhanced permeability and retention effect. Factors such as lack of cellular specificity, low vascular density, and early release of active agents prior to reaching their target contribute to the limitations of the enhanced permeability and retention effect. However, improved nanomedicine designs are creating opportunities to overcome these problems. In this review, we present examples of the advances made in this field and endeavor to highlight the potential of these emerging technologies to improve targeting of nanomedicine to specific pathological cells and tissues. PMID:24904213

Nehoff, Hayley; Parayath, Neha N; Domanovitch, Laura; Taurin, Sebastien; Greish, Khaled

2014-01-01

314

Nanomedicine for drug targeting: strategies beyond the enhanced permeability and retention effect.  

PubMed

The growing research interest in nanomedicine for the treatment of cancer and inflammatory-related pathologies is yielding encouraging results. Unfortunately, enthusiasm is tempered by the limited specificity of the enhanced permeability and retention effect. Factors such as lack of cellular specificity, low vascular density, and early release of active agents prior to reaching their target contribute to the limitations of the enhanced permeability and retention effect. However, improved nanomedicine designs are creating opportunities to overcome these problems. In this review, we present examples of the advances made in this field and endeavor to highlight the potential of these emerging technologies to improve targeting of nanomedicine to specific pathological cells and tissues. PMID:24904213

Nehoff, Hayley; Parayath, Neha N; Domanovitch, Laura; Taurin, Sebastien; Greish, Khaled

2014-01-01

315

Modified technique for permeability studies in the superfused hamster cheek pouch  

SciTech Connect

A modification of the superfused hamster cheek model for use in vascular permeability studies is reported. Radio-iodine labeled serum albumin (I-125 RISA) is injected prior to the superfusion period. Plasma content is calculated on a ..mu..1/100 mg wet weight basis and compared to the contralateral (non-superfused) cheek pouch. Water content is calculated on a percentage basis and compared in the same manner. Results demonstrate that superfusion causes an increase in permeability of protein and water. Plasma content is reduced by catalase, indomethacin or FPL 55712 pretreatment, suggesting that free-radicals, prostaglandins and leukotrienes are released during superfusion. Water content increase is refractory to pretreatment. The advantages of this system and its application are discussed.

Hambrecht, G.S.; Hilton, J.G.

1984-03-05

316

Rk1, a Ginsenoside, Is a New Blocker of Vascular Leakage Acting through Actin Structure Remodeling  

PubMed Central

Endothelial barrier integrity is essential for vascular homeostasis and increased vascular permeability and has been implicated in many pathological processes, including diabetic retinopathy. Here, we investigated the effect of Rk1, a ginsenoside extracted from sun ginseng, on regulation of endothelial barrier function. In human retinal endothelial cells, Rk1 strongly inhibited permeability induced by VEGF, advanced glycation end-product, thrombin, or histamine. Furthermore, Rk1 significantly reduced the vessel leakiness of retina in a diabetic mouse model. This anti-permeability activity of Rk1 is correlated with enhanced stability and positioning of tight junction proteins at the boundary between cells. Signaling experiments revealed that Rk1 induces phosphorylation of myosin light chain and cortactin, which are critical regulators for the formation of the cortical actin ring structure and endothelial barrier. These findings raise the possibility that ginsenoside Rk1 could be exploited as a novel prototype compound for the prevention of human diseases that are characterized by vascular leakage. PMID:23894330

Maeng, Yong-Sun; Maharjan, Sony; Kim, Jeong-Hun; Park, Jeong-Hill; Suk Yu, Young; Kim, Young-Myoung; Kwon, Young-Guen

2013-01-01

317

Vascular calcification: Mechanisms of vascular smooth muscle cell calcification.  

PubMed

Vascular calcification is highly prevalent and, when present, is associated with major adverse cardiovascular events. Vascular smooth muscle cells play an integral role in mediating vessel calcification by undergoing differentiation to osteoblast-like cells and generating matrix vesicles that serve as a nidus for calcium-phosphate deposition in the vessel wall. Once believed to be a passive process, it is now recognized that vascular calcification is a complex and highly regulated process that involves activation of cellular signaling pathways, circulating inhibitors of calcification, genetic factors, and hormones. This review will examine several of the key mechanisms linking vascular smooth muscle cells to vessel calcification that may be targeted to reduce vessel wall mineralization and, thereby, reduce cardiovascular risk. PMID:25435520

Leopold, Jane A

2014-10-30

318

Endothelial Cell Permeability during Hantavirus Infection Involves Factor XII-Dependent Increased Activation of the Kallikrein-Kinin System  

PubMed Central

Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) are diseases caused by hantavirus infections and are characterized by vascular leakage due to alterations of the endothelial barrier. Hantavirus-infected endothelial cells (EC) display no overt cytopathology; consequently, pathogenesis models have focused either on the influx of immune cells and release of cytokines or on increased degradation of the adherens junction protein, vascular endothelial (VE)-cadherin, due to hantavirus-mediated hypersensitization of EC to vascular endothelial growth factor (VEGF). To examine endothelial leakage in a relevant in vitro system, we co-cultured endothelial and vascular smooth muscle cells (vSMC) to generate capillary blood vessel-like structures. In contrast to results obtained in monolayers of cultured EC, we found that despite viral replication in both cell types as well as the presence of VEGF, infected in vitro vessels neither lost integrity nor displayed evidence of VE-cadherin degradation. Here, we present evidence for a novel mechanism of hantavirus-induced vascular leakage involving activation of the plasma kallikrein-kinin system (KKS). We show that incubation of factor XII (FXII), prekallikrein (PK), and high molecular weight kininogen (HK) plasma proteins with hantavirus-infected EC results in increased cleavage of HK, higher enzymatic activities of FXIIa/kallikrein (KAL) and increased liberation of bradykinin (BK). Measuring cell permeability in real-time using electric cell-substrate impedance sensing (ECIS), we identified dramatic increases in endothelial cell permeability after KKS activation and liberation of BK. Furthermore, the alterations in permeability could be prevented using inhibitors that directly block BK binding, the activity of FXIIa, or the activity of KAL. Lastly, FXII binding and autoactivation is increased on the surface of hantavirus-infected EC. These data are the first to demonstrate KKS activation during hantavirus infection and could have profound implications for treatment of hantavirus infections. PMID:23874198

Taylor, Shannon L.; Wahl-Jensen, Victoria; Copeland, Anna Maria; Jahrling, Peter B.; Schmaljohn, Connie S.

2013-01-01

319

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

320

Vascular Reactivity Is Impaired and Associated With Walking Ability in Patients With Intermittent Claudication.  

PubMed

We verified whether vascular reactivity is impaired and whether there is any association between vascular reactivity, walking ability, and peripheral artery disease (PAD) severity in patients with intermittent claudication (IC). We studied 63 patients and 17 age- and sex-matched volunteers without PAD. Vascular reactivity was evaluated in the brachial artery during reactive hyperemia (flow-mediated dilation [FMD]) and after a sublingual single dose of nitroglycerin (nitroglycerin-induced vasodilation [NID]). Walking ability was verified by a 6-minute walk test. Vascular reactivity and walking ability were significantly worse in patients with IC compared with control participants. The ankle-brachial index correlated with FMD, NID, as well as total and pain-free distances. The NID and walking ability progressively decreased as PAD severity increased. Walking ability correlated with NID but not with FMD. In patients with IC, vascular reactivity is impaired and is related to the severity of PAD and to walking ability. PMID:25100750

de Cassia Gengo E Silva, Rita; Wolosker, Nelson; Yugar-Toledo, Juan Carlos; Consolim-Colombo, Fernanda Marciano

2014-08-01

321

Vascular endothelial growth factor is upregulated by l-dopa in the parkinsonian brain: implications for the development of dyskinesia  

PubMed Central

Angiogenesis and increased permeability of the blood–brain barrier have been reported to occur in animal models of Parkinson’s disease and l-dopa-induced dyskinesia, but the significance of these phenomena has remained unclear. Using a validated rat model of l-dopa-induced dyskinesia, this study demonstrates that chronic treatment with l-dopa dose dependently induces the expression of vascular endothelial growth factor in the basal ganglia nuclei. Vascular endothelial growth factor was abundantly expressed in astrocytes and astrocytic processes in the proximity of blood vessels. When co-administered with l-dopa, a small molecule inhibitor of vascular endothelial growth factor signalling significantly attenuated the development of dyskinesia and completely blocked the angiogenic response and associated increase in blood–brain barrier permeability induced by the treatment. The occurrence of angiogenesis and vascular endothelial growth factor upregulation was verified in post-mortem basal ganglia tissue from patients with Parkinson’s disease with a history of dyskinesia, who exhibited increased microvascular density, microvascular nestin expression and an upregulation of vascular endothelial growth factor messenger ribonucleic acid. These congruent findings in the rat model and human patients indicate that vascular endothelial growth factor is implicated in the pathophysiology of l-dopa-induced dyskinesia and emphasize an involvement of the microvascular compartment in the adverse effects of l-dopa pharmacotherapy in Parkinson’s disease. PMID:21771855

Francardo, Veronica; Lindgren, Hanna S.; Sillivan, Stephanie E.; O’Sullivan, Sean S.; Luksik, Andrew S.; Vassoler, Fair M.; Lees, Andrew J.; Konradi, Christine

2011-01-01

322

The vascular contribution to Alzheimer’s disease  

PubMed Central

AD (Alzheimer’s disease) is a progressive neurodegenerative disease of unknown origin. Despite questions as to the underlying cause(s) of this disease, shared risk factors for both AD and atherosclerotic cardiovascular disease indicate that vascular mechanisms may critically contribute to the development and progression of both AD and atherosclerosis. An increased risk of developing AD is linked to the presence of the apoE4 (apolipoprotein E4) allele, which is also strongly associated with increased risk of developing atherosclerotic cardiovascular disease. Recent studies also indicate that cardiovascular risk factors, including elevated blood cholesterol and triacylglycerol (triglyceride), increase the likelihood of AD and vascular dementia. Lipids and lipoproteins in the circulation interact intimately with the cerebrovasculature, and may have important effects on its constituent brain microvascular endothelial cells and the adjoining astrocytes, which are components of the neurovascular unit. The present review will examine the potential mechanisms for understanding the contributions of vascular factors, including lipids, lipoproteins and cerebrovascular A? (amyloid ?), to AD, and suggest therapeutic strategies for the attenuation of this devastating disease process. Specifically, we will focus on the actions of apoE, TGRLs (triacylglycerol-rich lipoproteins) and TGRL lipolysis products on injury of the neurovascular unit and increases in blood–brain barrier permeability. PMID:20684749

Altman, Robin; Rutledge, John C.

2010-01-01

323

Vascular action of polyphenols.  

PubMed

Dietary patterns are widely recognised as contributors to cardiovascular and cerebrovascular disease. Endothelial function, the elastic properties of large arteries and the magnitude and timing of wave reflections are important determinants of cardiovascular performance. Several epidemiological studies suggest that the regular consumption of foods and beverages rich in flavonoids is associated with a reduction in the risk of several pathological conditions ranging from hypertension to coronary heart disease, stroke and dementia. The impairment of endothelial function is directly related to ageing and an association between decreased cerebral perfusion and dementia has been shown to exist. Cerebral blood flow (CBF) must be maintained to ensure a constant delivery of oxygen and glucose as well as the removal of waste products. Increasing blood flow is one potential way for improving brain function and the prospect for increasing CBF with dietary polyphenols is extremely promising. The major polyphenols shown to have some of these effects in humans are primarily from cocoa, wine, grape seed, berries, tea, tomatoes (polyphenolics and nonpolyphenolics), soy and pomegranate. There has been a significant paradigm shift in polyphenol research during the last decade. This review summarises our current knowledge in this area and points the way for the development of new types of functional foods targeted to brain health through improving vascular health. PMID:19051188

Ghosh, Dilip; Scheepens, Arjan

2009-03-01

324

Permeability of rayon based polymer composites  

NASA Technical Reports Server (NTRS)

Several types of anomalous rayon based phenolic behavior have been observed in post-fired nozzles and exit cones. Many of these events have been shown to be related to the development of internal gas pressure within the material. The development of internal gas pressure is a function of the amount of gas produced within the material and the rate at which that gas is allowed to escape. The latter property of the material is referred to as the material's permeability. The permeability of two dimensional carbonized rayon based phenolic composites is a function of material direction, temperature, and stress/strain state. Recently significant differences in the permeability of these materials has been uncovered which may explain their inconsistent performance. This paper summarizes what is known about the permeability of these materials to date and gives possible implications of these finding to the performance of these materials in an ablative environment.

Stokes, E. H.

1992-01-01

325

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

326

PERMEABILITY OF POLYMERIC MEMBRANE LINING MATERIALS  

EPA Science Inventory

Permeabilities to three gases (carbon dioxide, methane, and nitrogen), water vapor, and five solvents (methanol, acetone, cyclohexane, xylene, and chloroform) are reported for a broad range of commercial polymeric membranes. Gas and water vapor transmission (WVT) data were determ...

327

PERMEABLE REACTIVE BARRIERS FOR GROUND WATER REMEDIATION  

EPA Science Inventory

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

328

PERMEABLE REACTIVE BARRIERS FOR GROUNDWATER REMEDIATION  

EPA Science Inventory

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

329

Permeability After Impact Testing of Composite Laminates  

NASA Technical Reports Server (NTRS)

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Nettles, A.T.; Munafo, Paul (Technical Monitor)

2002-01-01

330

Permeability After Impact Testing of Composite Laminates  

NASA Technical Reports Server (NTRS)

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Nettles, Alan T.

2003-01-01

331

Innate immunity stimulates permeability barrier homeostasis.  

PubMed

A key function of the skin is to provide a permeability barrier to restrict the movement of water, electrolytes, and other small molecules between the outside environment and the internal milieu. Following disruption of the permeability barrier, there is a rapid restoration of barrier function, and one of the key signals initiating this repair response is a decrease in the concentration of calcium in the outer epidermis. In this issue, Borkowski et al. present evidence showing that activation of Toll receptor 3 by double-stranded RNA may be another pathway for activation of permeability barrier repair. These results provide further evidence for a link between innate immunity and the permeability barrier. PMID:23856931

Feingold, Kenneth R

2013-08-01

332

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

333

Interaction of steady jets with an array of permeable screens  

NASA Astrophysics Data System (ADS)

Turbulent flows in porous media have important practical applications such as enhanced mixing of fuel and air, food drying, and cooling of electronics. However, experimental studies of turbulence in porous media are sparse due to the difficulties of measuring the complex flow environment. To this end, the interactions of steady jets with a porous medium formed from several parallel, transparent, permeable screens are studied using digital particle image velocimetry in a refractive indexed-matched environment. The permeable screens had porosities (open area ratios, ?) of 83.8, 69.0, 55.7, and 49.5 % and were held by a transparent frame that allowed the screen spacing to be changed. The steady jet results for Reynolds number ( Re), which is defined based on the jet exit velocity and jet diameter, of 1000 showed laminar, predominantly steady flow that was segregated inside the porous medium, but for Re ? 2000, the flow was unsteady and turbulent with a mean velocity field that was relatively smooth inside the porous medium. As a result, more traditional jet features of self-similarity and increasing jet width were compared for the Re ? 2000 results. Decreasing the porosity was observed to increase the width of the jet significantly, especially for low porosity screens, and slowed the jet flow speed. Some of the typical features for axisymmetric jets were observed, even though the flow impinged on the permeable screens. In particular, self-similarity (or near self-similar behavior) was observed for the cross-sectional mean velocity profiles and for turbulence quantities for porosities larger than 55.7 % inside the porous medium. The effect of ? on turbulence quantities was significant for Re ? 2000. Although turbulence intensity increased on the downstream side of the first screen, the high dissipation forced drastic decrease of turbulence levels further downstream in the porous domain. Finally, the screens increased the removal of momentum from the jet as porosity decreased and screen spacing had a significant effect on the removal rate.

Musta, Mustafa N.; Krueger, Paul S.

2015-03-01

334

How to Prevent Vascular Disease  

MedlinePLUS

... City, CA 94063 @ 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, ...

335

Tissue engineering: Perfusable vascular networks  

NASA Astrophysics Data System (ADS)

A rapid vascular casting approach that uses carbohydrate glass as a sacrificial template allows tissues to be built that can be kept alive for longer in the laboratory until needed for transplantation.

Forgacs, Gabor

2012-09-01

336

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

337

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

338

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

PubMed

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

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

1995-01-01

339

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

340

Hormone interactions during vascular development  

Microsoft Academic Search

Vascular tissue in plants is unique due to its diverse and dynamic cellular patterns. Signals controlling vascular development\\u000a have only recently started to emerge through biochemical, genetic, and genomic approaches in several organisms, such as Arabidopsis, Populus, and Zinnia. These signals include hormones (auxin, brassinosteroids, and cytokinins, in particular), other small regulatory molecules,\\u000a their transporters, receptors, and various transcriptional regulators.

Jan Dettmer; Annakaisa Elo; Ykä Helariutta

2009-01-01

341

Echocardiography in Pulmonary Vascular Disease  

Microsoft Academic Search

\\u000a This chapter will focus on the principles and uses of the Doppler echocardiography (DE) examination in patients with pulmonary\\u000a vascular disease (PVD). That is, patients who have pulmonary hypertension that is related to a marked increase in the pulmonary\\u000a vascular resistance (PVR) and loss of large pulmonary artery (PA) compliance. We will also address the role of DE in the

Paul R. Forfia

342

Infrared Imaging Of Vascular Changes  

NASA Astrophysics Data System (ADS)

Infrared thermography is a useful method of recording skin temperature distributions. It can be shown that the thermal pattern of an individual is a complex function of surface topography, anatomy, blood perfusion in subcutaneous tissues, superficial vascularity and environmental temperature. A variety of physiological and pathological factors can also affect skin temperature. Three examples are illustrated: the scrotal varicocele, vascular changes associated with malignancy and the effect of large doses of ionizing radiation on the skin.

Jones, Colin H.

1988-10-01

343

Vascular tumors simulating occlusive disease.  

PubMed

Two cases of vascular tumors of large vessels with intraluminal growth simulating venous thrombosis and arterial occlusive disease are reported. One was a borderline malignant epithelioid hemangioendothelioma of the femoral vein and the other a malignant epithelioid angiosarcoma of the carotid artery. Immunohistochemical studies permitted to classify the tumors. Treatment consisted in surgical resection. No recurrence and no metastasis are noted at 24 months. Uncertainty regarding biological behaviour of vascular tumors and treatment persists. PMID:11284093

Schröder, A; Peters, A; Riepe, G; Larena, A; Meierling, S; Mentzel, T; Katenkamp, D; Imig, H

2001-02-01

344

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

345

Pulmonary vascular effects of fat emulsion infusion in unanesthetized sheep. Prevention by indomethacin.  

PubMed

Pulmonary diffusing capacity and arterial blood Po(2) decrease in humans when 10% fat emulsion is infused. To study its effects on the pulmonary circulation and lung fluid balance, we infused 0.25 g/kg x h of a 10% fat emulsion (Intralipid, Cutter Laboratories, Inc., Berkeley, Calif.) into an awake sheep lung lymph preparation. The emulsion caused a sustained increase in pulmonary artery pressure to approximately twice base line with little change in left atrial pressure. Pa(O2) decreased an average 13 torr and lung lymph flow increased two- to threefold. Lymph/plasma total protein concentration fell as lymph flow increased; the magnitude of the lymph/plasma protein decrease was similar to that reported previously when lung vascular pressures were mechanically elevated. Heparin infusion (loading dose = 4,000 U, maintenance dose = 2,000 U/h) cleared the serum of triglycerides but did not alter the response to fat emulsion. Indomethacin infusion (loading dose = 5 mg/kg, maintenance dose = 3 mg/kg x h) blocked the rise in pulmonary artery pressure, the increase in lung lymph flow, and the fall in Pa(O2). Neither extravascular lung water nor [(14)C]urea lung vascular permeability surface area products were altered by fat emulsion infusion. We conclude that fat emulsion infusion in sheep increases lung microvascular filtration by increasing vascular pressures, but has no effect on vascular permeability. Since the effects are blocked by indomethacin, they may be prostaglandin mediated. PMID:659593

McKeen, C R; Brigham, K L; Bowers, R E; Harris, T R

1978-05-01

346

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

347

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

348

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

349

From Low-loss to Lossless Optical Negative-Index Materials U. K. Chettiar, A. V. Kildishev, T. A. Klar, H.-K. Yuan, W. Cai, A. K. Sarychev  

E-print Network

(metamaterials) in which the effective refractive index ( effn ) is negative. A truly negative index 0effn where the effective isotropic properties (permit- tivity i = + and permeability i = + ) obey active metamaterial arranged of two split ring resonantors (SRRs) of subwavelength dimensions

Shalaev, Vladimir M.

350

Negative index metamaterial combining magnetic resonators with metal films  

Microsoft Academic Search

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

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

2006-01-01

351

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

352

The effect of interstitial pressure on therapeutic agent transport: coupling with the tumor blood and lymphatic vascular systems.  

PubMed

Vascularized tumor growth is characterized by both abnormal interstitial fluid flow and the associated interstitial fluid pressure (IFP). Here, we study the effect that these conditions have on the transport of therapeutic agents during chemotherapy. We apply our recently developed vascular tumor growth model which couples a continuous growth component with a discrete angiogenesis model to show that hypertensive IFP is a physical barrier that may hinder vascular extravasation of agents through transvascular fluid flux convection, which drives the agents away from the tumor. This result is consistent with previous work using simpler models without blood flow or lymphatic drainage. We consider the vascular/interstitial/lymphatic fluid dynamics to show that tumors with larger lymphatic resistance increase the agent concentration more rapidly while also experiencing faster washout. In contrast, tumors with smaller lymphatic resistance accumulate less agents but are able to retain them for a longer time. The agent availability (area-under-the curve, or AUC) increases for less permeable agents as lymphatic resistance increases, and correspondingly decreases for more permeable agents. We also investigate the effect of vascular pathologies on agent transport. We show that elevated vascular hydraulic conductivity contributes to the highest AUC when the agent is less permeable, but to lower AUC when the agent is more permeable. We find that elevated interstitial hydraulic conductivity contributes to low AUC in general regardless of the transvascular agent transport capability. We also couple the agent transport with the tumor dynamics to simulate chemotherapy with the same vascularized tumor under different vascular pathologies. We show that tumors with an elevated interstitial hydraulic conductivity alone require the strongest dosage to shrink. We further show that tumors with elevated vascular hydraulic conductivity are more hypoxic during therapy and that the response slows down as the tumor shrinks due to the heterogeneity and low concentration of agents in the tumor interior compared with the cases where other pathological effects may combine to flatten the IFP and thus reduce the heterogeneity. We conclude that dual normalizations of the micronevironment - both the vasculature and the interstitium - are needed to maximize the effects of chemotherapy, while normalization of only one of these may be insufficient to overcome the physical resistance and may thus lead to sub-optimal outcomes. PMID:24751927

Wu, Min; Frieboes, Hermann B; Chaplain, Mark A J; McDougall, Steven R; Cristini, Vittorio; Lowengrub, John S

2014-08-21

353

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

354

Permeability-controlled optical modulator with Tri-gate metamaterial: control of permeability on InP-based photonic integration platform.  

PubMed

Metamaterials are artificially structured materials that can produce innovative optical functionalities such as negative refractive index, invisibility cloaking, and super-resolution imaging. Combining metamaterials with semiconductors enables us to develop novel optoelectronic devices based on the new concept of operation. Here we report the first experimental demonstration of a permeability-controlled waveguide optical modulator consisting of an InGaAsP/InP Mach-Zehnder interferometer with 'tri-gate' metamaterial attached on its arms. The tri-gate metamaterial consists of metal resonator arrays and triple-gate field effect elements. It changes its permeability with a change in the controlling gate voltage, thereby changing the refractive index of the interferometer arm to switch the modulator with an extinction ratio of 6.9?dB at a wavelength of 1.55??m. The result shows the feasibility of InP-based photonic integrated devices that can produce new functions by controlling their permeability as well as their permittivity. PMID:25797041

Amemiya, Tomohiro; Ishikawa, Atsushi; Kanazawa, Toru; Kang, JoonHyung; Nishiyama, Nobuhiko; Miyamoto, Yasuyuki; Tanaka, Takuo; Arai, Shigehisa

2015-01-01

355

Permeability-controlled optical modulator with Tri-gate metamaterial: control of permeability on InP-based photonic integration platform  

PubMed Central

Metamaterials are artificially structured materials that can produce innovative optical functionalities such as negative refractive index, invisibility cloaking, and super-resolution imaging. Combining metamaterials with semiconductors enables us to develop novel optoelectronic devices based on the new concept of operation. Here we report the first experimental demonstration of a permeability-controlled waveguide optical modulator consisting of an InGaAsP/InP Mach-Zehnder interferometer with ‘tri-gate’ metamaterial attached on its arms. The tri-gate metamaterial consists of metal resonator arrays and triple-gate field effect elements. It changes its permeability with a change in the controlling gate voltage, thereby changing the refractive index of the interferometer arm to switch the modulator with an extinction ratio of 6.9?dB at a wavelength of 1.55??m. The result shows the feasibility of InP-based photonic integrated devices that can produce new functions by controlling their permeability as well as their permittivity. PMID:25797041

Amemiya, Tomohiro; Ishikawa, Atsushi; Kanazawa, Toru; Kang, JoonHyung; Nishiyama, Nobuhiko; Miyamoto, Yasuyuki; Tanaka, Takuo; Arai, Shigehisa

2015-01-01

356

Differentiation of Multipotent Vascular Stem Cells Contributes to Vascular Diseases  

PubMed Central

It is generally accepted that the de-differentiation of smooth muscle cells (SMCs) from contractile to proliferative/synthetic phenotype has an important role during vascular remodeling and diseases. Here we provide evidence that challenges this theory. We identify a new type of multipotent vascular stem cell (MVSC) in blood vessel wall. MVSCs express markers including Sox17, Sox10 and S100?, are cloneable, have telomerase activity, and can differentiate into neural cells and mesenchymal stem cell (MSC)-like cells that subsequently differentiate into SMCs. On the other hand, we use lineage tracing with smooth muscle myosin heavy chain as a marker to show that MVSCs and proliferative or synthetic SMCs do not arise from the de-differentiation of mature SMCs. Upon vascular injuries, MVSCs, instead of SMCs, become proliferative, and MVSCs can differentiate into SMCs and chondrogenic cells, thus contributing to vascular remodeling and neointimal hyperplasia. These findings support a new hypothesis that the differentiation of MVSCs, rather than the de-differentiation of SMCs, contributes to vascular remodeling and diseases. PMID:22673902

Tang, Zhenyu; Wang, Aijun; Yuan, Falei; Yan, Zhiqiang; Liu, Bo; Chu, Julia S.; Helms, Jill A.

2012-01-01

357

Determination of the Effective-Stress Law for Permeability and Deformation in Low-Permeability Rocks  

Microsoft Academic Search

This paper reports that laboratory experiments were performed to determine the effective stress law of tight sandstones and chalk for permeability and deformation. Permeability and volumetric strain data were taken at various stresses and pore pressures and were analyzed with a statistical model-building approach. Results show that the effective stress laws for both processes are variable with stress and pressure,

N. R. Warpinski; L. W. Teufel

1992-01-01

358

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

E-print Network

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

Petta, Jason

359

Testing and Modeling the Hydraulic Permeability Evolution of Permeable Reactive Barriers Clogged by Colloids  

Microsoft Academic Search

This paper deals with the clogging by colloids of Permeable Reactive Barriers (PRB), used to treat the groundwater pollutants in situ. PRBs are composed of reactive and permeable filters, whose longevity has to be studied from hydraulic and chemical points of view. It is thus necessary to develop a model able to predict the evolution of their hydraulic conductivity. A

Benoît Courcelles; Arezou Modaressi Farahmand-Razavi; Daniel Gouvenot; Annette Esnault-Filet

360

Amyloid-?-induced occludin down-regulation and increased permeability in human brain endothelial cells is mediated by MAPK activation  

PubMed Central

Abstract Vascular dysfunction is emerging as a key pathological hallmark in Alzheimer’s disease (AD). A leaky blood–brain barrier (BBB) has been described in AD patient tissue and in vivo AD mouse models. Brain endothelial cells (BECs) are linked together by tight junctional (TJ) proteins, which are a key determinant in restricting the permeability of the BBB. The amyloid ? (A?) peptides of 1–40 and 1–42 amino acids are believed to be pivotal in AD pathogenesis. We therefore decided to investigate the effect of A? 1–40, the A? variant found at the highest concentration in human plasma, on the permeability of an immortalized human BEC line, hCMEC/D3. A? 1–40 induced a marked increase in hCMEC/D3 cell permeability to the paracellular tracer 70 kD FITC-dextran when compared with cells incubated with the scrambled A? 1–40 peptide. Increased permeability was associated with a specific decrease, both at the protein and mRNA level, in the TJ protein occludin, whereas claudin-5 and ZO-1 were unaffected. JNK and p38MAPK inhibition prevented both A? 1–40-mediated down-regulation of occludin and the increase in paracellular permeability in hCMEC/D3 cells. Our findings suggest that the JNK and p38MAPK pathways might represent attractive therapeutic targets for preventing BBB dysfunction in AD. PMID:19438816

Tai, L M; Holloway, K A; Male, D K; Loughlin, A J; Romero, I A

2010-01-01

361

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...

362

Intestinal permeability is increased in bronchial asthma  

PubMed Central

Background: Increased intestinal permeability has been reported in one study of adult asthmatics. Aim: To determine whether children with asthma have altered intestinal permeability. Methods: Thirty two asthmatic children, and 32 sex and age matched controls were recruited. The dual sugar (lactulose and mannitol) test was used to evaluate intestinal permeability, and the percentage of ingested lactulose (L) and mannitol (M) in the urine, and the L:M ratio were determined. All patients were skin prick tested for common aeroallergens, and specific IgE to some food items was determined. Results: The median value of L in asthmatic children (2.29, IQR 0.91–4.07) was significantly higher than that in controls (0.69, IQR 0.45–1.08), and that of M was almost similar. The ratio L:M was significantly higher in asthmatic children (0.20, IQR 0.11–0.40) than in controls (0.06, IQR 0.04–0.09). Intestinal permeability did not correlate with eczema, inhaled steroids, positive skin prick test to aeroallergens, or severity of asthma. Conclusions: Intestinal permeability is increased in children with asthma, suggesting that the whole mucosal system may be affected. PMID:14977697

Hijazi, Z; Molla, A; Al-Habashi, H; Muawad, W; Molla, A; Sharma, P

2004-01-01

363

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

364

Microfluidic models of vascular functions.  

PubMed

In vitro studies of vascular physiology have traditionally relied on cultures of endothelial cells, smooth muscle cells, and pericytes grown on centimeter-scale plates, filters, and flow chambers. The introduction of microfluidic tools has revolutionized the study of vascular physiology by allowing researchers to create physiologically relevant culture models, at the same time greatly reducing the consumption of expensive reagents. By taking advantage of the small dimensions and laminar flow inherent in microfluidic systems, recent studies have created in vitro models that reproduce many features of the in vivo vascular microenvironment with fine spatial and temporal resolution. In this review, we highlight the advantages of microfluidics in four areas: the investigation of hemodynamics on a capillary length scale, the modulation of fluid streams over vascular cells, angiogenesis induced by the exposure of vascular cells to well-defined gradients in growth factors or pressure, and the growth of microvascular networks in biomaterials. Such unique capabilities at the microscale are rapidly advancing the understanding of microcirculatory dynamics, shear responses, and angiogenesis in health and disease as well as the ability to create in vivo-like blood vessels in vitro. PMID:22540941

Wong, Keith H K; Chan, Juliana M; Kamm, Roger D; Tien, Joe

2012-01-01

365

Tumor MMP-1 Activates Endothelial PAR1 to Facilitate Vascular Intravasation and Metastatic Dissemination  

PubMed Central

Intravasation, the active entry of primary tumor cells into the vasculature, remains the least studied step in the metastatic cascade. Protease-mediated escape and stromal invasion of tumor cells represent widely-accepted processes leading up to the intravasation step. However, molecular factors that contribute directly to tumor cell vascular penetration have not been identified. In this study, the in vivo role of the collagenolytic protease, MMP-1, in cancer cell intravasation and metastasis was analyzed by employing a highly-disseminating variant of human HEp3 epidermoid carcinoma, HEp3-hi/diss. Whereas naturally-acquired or experimentally-induced MMP-1 deficiency substantially suppressed HEp3-hi/diss intravasation, supplementation of recombinant MMP-1 to MMP-1-silenced primary tumors, restored their impaired vascular dissemination. Surprisingly, abrogation of MMP-1 production and activity did not affect significantly HEp3-hi/diss migration or matrix invasion, suggesting non-collagenolytic mechanisms underlying MMP-1-dependent cell intravasation. In support of such non-collagenolytic mechanisms, MMP-1 silencing in HEp3-hi/diss cells modulated the microarchitecture and integrity of the angiogenic vasculature in a novel microtumor model. Concomitantly, MMP-1 deficiency led to decreased levels of intratumoral vascular permeability, tumor cell intravasation and metastatic dissemination. Taking advantage of PAR1 deficiency of HEp3-hi/diss cells, we further demonstrate that endothelial PAR1 is a putative non-tumor-cell/non-matrix target, activation of which by carcinoma-produced MMP-1 regulates endothelial permeability and transendothelial migration. The inhibitory effects of specific PAR1 antagonists in live animals have also indicated that the mechanisms of MMP-1-dependent vascular permeability in tumors involve endothelial PAR1 activation. Together, our findings mechanistically underscore the contribution of a tumor MMP-1/endothelial PAR1 axis to actual intravasation events manifested by aggressive carcinoma cells. PMID:23687338

Juncker-Jensen, Anna; Deryugina, Elena I.; Rimann, Ivo; Zajac, Ewa; Kupriyanova, Tatyana A.; Engelholm, Lars H.; Quigley, James P.

2013-01-01

366

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

367

Proteomics-Based Metabolic Modeling Reveals That Fatty Acid Oxidation (FAO) Controls Endothelial Cell (EC) Permeability*  

PubMed Central

Endothelial cells (ECs) play a key role to maintain the functionality of blood vessels. Altered EC permeability causes severe impairment in vessel stability and is a hallmark of pathologies such as cancer and thrombosis. Integrating label-free quantitative proteomics data into genome-wide metabolic modeling, we built up a model that predicts the metabolic fluxes in ECs when cultured on a tridimensional matrix and organize into a vascular-like network. We discovered how fatty acid oxidation increases when ECs are assembled into a fully formed network that can be disrupted by inhibiting CPT1A, the fatty acid oxidation rate-limiting enzyme. Acute CPT1A inhibition reduces cellular ATP levels and oxygen consumption, which are restored by replenishing the tricarboxylic acid cycle. Remarkably, global phosphoproteomic changes measured upon acute CPT1A inhibition pinpointed altered calcium signaling. Indeed, CPT1A inhibition increases intracellular calcium oscillations. Finally, inhibiting CPT1A induces hyperpermeability in vitro and leakage of blood vessel in vivo, which were restored blocking calcium influx or replenishing the tricarboxylic acid cycle. Fatty acid oxidation emerges as central regulator of endothelial functions and blood vessel stability and druggable pathway to control pathological vascular permeability. PMID:25573745

Patella, Francesca; Schug, Zachary T.; Persi, Erez; Neilson, Lisa J.; Erami, Zahra; Avanzato, Daniele; Maione, Federica; Hernandez-Fernaud, Juan R.; Mackay, Gillian; Zheng, Liang; Reid, Steven; Frezza, Christian; Giraudo, Enrico; Fiorio Pla, Alessandra; Anderson, Kurt; Ruppin, Eytan; Gottlieb, Eyal; Zanivan, Sara

2015-01-01

368

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

369

Permeability and effective pore pressure of shales  

SciTech Connect

Laboratory-derived permeability and pore-pressure data obtained for Wellington and Pierre shales are used to describe swelling pressure, and spalling types of wellbore instability. Tests showed that increased pore pressures can lead to wellbore failure. The laboratory pore-pressure information developed displays a time-dependent swelling process followed by a Darcy type of flow. A total aqueous chemical potential concept is presented that describes the driving potentials that operate during both phases of flow. Experimental methods are presented to determine the storage of water shale during the swelling phase and the permeabilities with steady-state-flow and transient-flow techniques. Permeability values measured under effective stresses up to 8,000 psi show the Wellington shale to have values as low as 0.30 [times] 10[sup [minus]6] md.

Chenevert, M.E.; Sharma, A.K. (Univ. of Texas, Austin (United States))

1993-03-01

370

Intestinal permeability in piglets during transmissible gastroenteritis.  

PubMed

Macromolecular permeability of the small intestine was tested in seven three-week-old piglets infected with porcine transmissible gastroenteritis virus (TGE-strain Miller). Fourteen hours after the infection, the piglets showed loss of appetite and a profuse diarrhoea. In some animals vomiting occurred somewhat earlier. Macromolecular permeability was tested morphologically by injecting horseradish peroxidase (MW = 40,000 Da) into the jejunal lumen just distally to the Treitz' ligament in two piglets at 12 hours and in five piglets at 48 hours after the inoculation in comparison with two control piglets. After a period of 20 minutes, small segments of jejunum were taken for stereomicro-scopical, histological and ultrastructural investigations. An increased permeability for HRP together with a severe, hyper-regenerative villous atrophy was observed in the TGE-infected piglets at 48 hours after the inoculation. PMID:1830439

Egberts, H J; Vellenga, L; van Dijk, J E; Mouwen, J M

1991-04-01

371

Differential apicobasal VEGF signaling at vascular blood-neural barriers.  

PubMed

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

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

2014-09-01

372

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

373

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

374

Vascular ultrasound for atherosclerosis imaging  

PubMed Central

Cardiovascular disease is a leading cause of death in the Western world. Therefore, detection and quantification of atherosclerotic disease is of paramount importance to monitor treatment and possible prevention of acute events. Vascular ultrasound is an excellent technique to assess the geometry of vessel walls and plaques. The high temporal as well as spatial resolution allows quantification of luminal area and plaque size and volume. While carotid arteries can be imaged non-invasively, scanning of coronary arteries requires invasive intravascular catheters. Both techniques have already demonstrated their clinical applicability. Using linear array technology, detection of disease as well as monitoring of pharmaceutical treatment in carotid arteries are feasible. Data acquired with intravascular ultrasound catheters have proved to be especially beneficial in understanding the development of atherosclerotic disease in coronary arteries. With the introduction of vascular elastography not only the geometry of plaques but also the risk for rupture of plaques might be identified. These so-called vulnerable plaques are frequently not flow-limiting and rupture of these plaques is responsible for the majority of cerebral and cardiac ischaemic events. Intravascular ultrasound elastography studies have demonstrated a high correlation between high strain and vulnerable plaque features, both ex vivo and in vivo. Additionally, pharmaceutical intervention could be monitored using this technique. Non-invasive vascular elastography has recently been developed for carotid applications by using compound scanning. Validation and initial clinical evaluation is currently being performed. Since abundance of vasa vasorum (VV) is correlated with vulnerable plaque development, quantification of VV might be a unique tool to even prevent this from happening. Using ultrasound contrast agents, it has been demonstrated that VV can be identified and quantified. Although far from routine clinical application, non-invasive and intravascular ultrasound VV imaging might pave the road to prevent atherosclerotic disease in an early phase. This paper reviews the conventional vascular ultrasound techniques as well as vascular ultrasound strain and vascular ultrasound VV imaging. PMID:22866231

de Korte, Chris L.; Hansen, Hendrik H. G.; van der Steen, Anton F. W.

2011-01-01

375

Angiopoietin-1 opposes VEGF-induced increase in endothelial permeability by inhibiting TRPC1-dependent Ca2 influx.  

PubMed

Angiopoietin-1 (Ang1) exerts a vascular endothelial barrier protective effect by blocking the action of permeability-increasing mediators such as vascular endothelial growth factor (VEGF) through unclear mechanisms. Because VEGF may signal endothelial hyperpermeability through the phospholipase C (PLC)-IP3 pathway that activates extracellular Ca2+ entry via the plasmalemmal store-operated channel transient receptor potential canonical-1 (TRPC1), we addressed the possibility that Ang1 acts by inhibiting this Ca2+ entry mechanism in endothelial cells. Studies in endothelial cell monolayers demonstrated that Ang1 inhibited the VEGF-induced Ca2+ influx and increase in endothelial permeability in a concentration-dependent manner. Inhibitors of the PLC-IP3 Ca2+ signaling pathway prevented the VEGF-induced Ca2+ influx and hyperpermeability similar to the inhibitory effects seen with Ang1. Ang1 had no effect on PLC phosphorylation and IP3 production, thus its permeability-decreasing effect could not be ascribed to inhibition of PLC activation. However, Ang1 interfered with downstream IP3-dependent plasmalemmal Ca2+ entry without affecting the release of intracellular Ca2+ stores. Anti-TRPC1 antibody inhibited the VEGF-induced Ca2+ entry and the increased endothelial permeability. TRPC1 overexpression in endothelial cells augmented the VEGF-induced Ca2+ entry, and application of Ang1 opposed this effect. In immunoprecipitation studies, Ang1 inhibited the association of IP3 receptor (IP3R) and TRPC1, consistent with the coupling hypothesis of Ca2+ entry. These results demonstrate that Ang1 blocks the TRPC1-dependent Ca2+ influx induced by VEGF by interfering with the interaction of IP3R with TRPC1, and thereby abrogates the increase in endothelial permeability. PMID:15920022

Jho, David; Mehta, Dolly; Ahmmed, Gias; Gao, Xiao-Pei; Tiruppathi, Chinnaswamy; Broman, Michael; Malik, Asrar B

2005-06-24

376

Nuclear receptors in vascular biology.  

PubMed

Nuclear receptors sense a wide range of steroids and hormones (estrogens, progesterone, androgens, glucocorticoid, and mineralocorticoid), vitamins (A and D), lipid metabolites, carbohydrates, and xenobiotics. In response to these diverse but critically important mediators, nuclear receptors regulate the homeostatic control of lipids, carbohydrate, cholesterol, and xenobiotic drug metabolism, inflammation, cell differentiation and development, including vascular development. The nuclear receptor family is one of the most important groups of signaling molecules in the body and as such represent some of the most important established and emerging clinical and therapeutic targets. This review will highlight some of the recent trends in nuclear receptor biology related to vascular biology. PMID:25772409

Bishop-Bailey, David

2015-05-01

377

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.

378

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

379

Lipid membrane with low proton permeability.  

PubMed

This work reports the production of a liposomal formulation, having a lipidic membrane with known chemical composition and a low proton permeability, as confirmed by physicochemical characterization of the maintenance of a transmembranic pH gradient. These liposomes consist of DSPC, DSPE-PEG, DSPG and cholesterol, with low internal pH. To verify the low proton permeability of these liposomal bilayers, a study of proton migration according to the fluorescence quenching of 9-aminoacridine (9AA), as well as CPT-11 encapsulation, were used to monitor the acidification of the intravesicular space. Both experiments showed that this liposomal formulation is able to maintain a transmembranic proton gradient. PMID:12659939

Biloti, Débora Nakai; Santana, Maria Helena Andrade; Pessine, Francisco Benedito Teixeira

2003-04-01

380

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 35 nm phenylalanine-modified poly(?-Glutamic Acid) nanoparticles (?-PGA-Phe NPs) as a candidate of biodegradable drug carrier. Interestingly, despite of having comparable size to dextran-2000 k (28 nm), 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

381

Intimal permeability evaluated in a short-term organ culture of diabetic guinea pig aorta  

SciTech Connect

A novel short-term organ culture system was used to evaluate intimal permeability changes by measuring aortic (/sup 14/C)methylated albumin accumulation. Aortic plugs were removed from the upper thoracic aorta of male guinea pigs and maintained in serum-free media. The accumulation of (/sup 14/C)albumin in the intimal-medial layer was determined after a 5 h incubation. In preliminary studies, albumin recovered from intimal-injured aortic plugs was significantly greater than those from non-injured plugs. Aortic plugs from streptozotocin-treated guinea pigs, diabetic for 3 weeks, also accumulated significantly more (/sup 14/C)albumin than plugs from nondiabetic controls. Histological changes were not observed in the aorta of either the diabetic or control group. A strong significant inverse correlation was found between plasma ascorbic acid levels and (/sup 14/C)-activity recovered from aortic plugs. This study demonstrates a simple and rapid method for assessing aortic permeability changes under a well-defined in vitro system, and suggests that vascular permeability changes in the streptozotocin-diabetic guinea pig may be associated with an ascorbic acid deficit.

Schlosser, M.J.; Verlangieri, A.J.

1988-01-01

382

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

383

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

384

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

385

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

386

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

PubMed

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

2015-02-10

387

Indexing Consistency and Quality.  

ERIC Educational Resources Information Center

A measure of indexing consistency is developed based on the concept of 'fuzzy sets'. It assigns a higher consistency value if indexers agree on the more important terms than if they agree on less important terms. Measures of the quality of an indexer's work and exhaustivity of indexing are also proposed. Experimental data on indexing consistency…

Zunde, Pranas; Dexter, Margaret E.

388

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

389

Vascular Subcortical Dementias: Clinical Aspects  

Microsoft Academic Search

Vascular dementia (VAD) is common, and small vessel disease is one of the most frequent etiologies of the disorder. Lacunar state and Binswanger's disease are the two types of VAD associated with small vessel disease. Lacunar state and Binswanger's disease produce a dementia syndrome with characteristics of subcortical dementia including slowing of information processing, impaired memory, and poor sustained attention.

Jeffrey L. Cummings

1994-01-01

390

The Neurochemistry of Vascular Dementia  

Microsoft Academic Search

Vascular dementia (VAD) is cognitive impairment caused by changes in the blood circulation of the brain. It is not synonymous with multi-infarct dementia. The latter is a subgroup of VAD. Neurochemical investigations of noninfarcted brain tissue from patients with VAD show general changes in VAD brains. The serotonin metabolism is severely reduced and so is the activity of choline acetyltransferase.

C. G. Gottfries; K. Blennow; I. Karlsson; A. Wallin

1994-01-01

391

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

392

Renal Vascular Resistance in Sepsis  

Microsoft Academic Search

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

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

2006-01-01

393

Hyperglycemia is a major determinant of albumin permeability in diabetic microcirculation: the role of mu-calpain.  

PubMed

Increased permeability to albumin is a well-known feature of diabetic microvasculature and a negative prognostic factor of vascular complications. The mechanisms responsible for loss of the physiological albumin barrier in diabetic organs remain only partially understood. We have recently demonstrated that the protease mu-calpain is activated in hyperglycemia, which causes endothelial dysfunction and vascular inflammation. In the present study, we investigated whether mu-calpain is involved in the hyperpermeability of the diabetic vasculature. We also investigated the mechanistic roles of hyperglycemia and leukocyte adhesion in this process. Albumin permeability in the intact microcirculation of the Zucker diabetic fatty (ZDF) rat was quantified by intravital microscopy. Extravasation of albumin in the microcirculation of ZDF rats was significantly increased when compared with nondiabetic Zucker lean (ZL) rats. Microvascular albumin leakage was prevented by either antisense depletion of mu-calpain or pharmacological inhibition of calpain in vivo. Calpain inhibition also attenuated urinary albumin excretion in ZDF rats. Glucose concentrations in the range of those found in the blood of ZDF rats increased albumin permeability in nondiabetic ZL rats. Thus, this demonstrates a mechanistic role for hyperglycemia in the hypermeability of diabetes. Depletion of polymorphonuclear leukocytes in vivo failed to prevent glucose-induced hypermeability, which suggests that hyperglycemia can disrupt the physiological endothelial cell barrier of the microcirculation, even in the absence of increased overt leukocyte-endothelium interactions. PMID:17446533

Scalia, Rosario; Gong, Yulan; Berzins, Brett; Zhao, Li Juan; Sharma, Kumar

2007-07-01

394

Clostridium perfringens epsilon-toxin increases permeability of single perfused microvessels of rat mesentery.  

PubMed

Epsilon-toxin, the primary virulence factor of Clostridium perfringens type D, causes mortality in livestock, particularly sheep and goats, in which it induces an often-fatal enterotoxemia. It is believed to compromise the intestinal barrier and then enter the gut vasculature, from which it is carried systemically, causing widespread vascular endothelial damage and edema. Here we used single perfused venular microvessels in rat mesentery, which enabled direct observation of permeability properties of the in situ vascular wall during exposure to toxin. We determined the hydraulic conductivity (L(p)) of microvessels as a measure of the response to epsilon-toxin. We found that microvessels were highly sensitive to toxin. At 10 microg ml(-1) the L(p) increased irreversibly to more than 15 times the control value by 10 min. At 0.3 microg ml(-1) no increase in L(p) was observed for up to 90 min. The toxin-induced increase in L(p) was consistent with changes in ultrastructure of microvessels exposed to the toxin. Those microvessels exhibited gaps either between or through endothelial cells where perfusate had direct access to the basement membrane. Many endothelial cells appeared necrotic, highly attenuated, and with dense cytoplasm. We showed that epsilon-toxin, in a time- and dose-dependent manner, rapidly and irreversibly compromised the barrier function of venular microvessel endothelium. The results conformed to the hypothesis that epsilon-toxin interacts with vascular endothelial cells and increases the vessel wall permeability by direct damage of the endothelium. PMID:16041001

Adamson, R H; Ly, J C; Fernandez-Miyakawa, M; Ochi, S; Sakurai, J; Uzal, F; Curry, F E

2005-08-01

395

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

PubMed

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

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

2013-04-01

396

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

PubMed Central

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

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

2013-01-01

397

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

398

Critical role of sphingosine-1-phosphate receptor 2 (S1PR2) in acute vascular inflammation  

PubMed Central

The endothelium, as the interface between blood and all tissues, plays a critical role in inflammation. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid, highly abundant in plasma, that potently regulates endothelial responses through interaction with its receptors (S1PRs). Here, we studied the role of S1PR2 in the regulation of the proadhesion and proinflammatory phenotype of the endothelium. By using genetic approaches and a S1PR2-specific antagonist (JTE013), we found that S1PR2 plays a key role in the permeability and inflammatory responses of the vascular endothelium during endotoxemia. Experiments with bone marrow chimeras (S1pr2+/+ ? S1pr2+/+, S1pr2+/+ ? S1pr2?/?, and S1pr2?/? ? S1pr2+/+) indicate the critical role of S1PR2 in the stromal compartment, in the regulation of vascular permeability and vascular inflammation. In vitro, JTE013 potently inhibited tumor necrosis factor ?–induced endothelial inflammation. Finally, we provide detailed mechanisms on the downstream signaling of S1PR2 in vascular inflammation that include the activation of the stress-activated protein kinase pathway that, together with the Rho-kinase nuclear factor kappa B pathway (NF-kB), are required for S1PR2-mediated endothelial inflammatory responses. Taken together, our data indicate that S1PR2 is a key regulator of the proinflammatory phenotype of the endothelium and identify S1PR2 as a novel therapeutic target for vascular disorders. PMID:23723450

Zhang, Guoqi; Yang, Li; Kim, Gab Seok; Ryan, Kieran; Lu, Shulin; O’Donnell, Rebekah K.; Spokes, Katherine; Shapiro, Nathan; Aird, William C.; Kluk, Michael J.; Yano, Kiichiro

2013-01-01

399

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!

2012-11-14

400

Intestinal permeability in the ileal pouch.  

PubMed Central

BACKGROUND: Villous atrophy, mucin changes ('colonic metaplasia'), and chronic inflammation occur to varying degrees in all patients with ileal pouchanal anastomosis whereas acute inflammation (pouchitis) affects a subgroup of patients with prior ulcerative colitis. AIM: To measure epithelial barrier function looking for possible functional adaptation in ileal 'pouch' mucosa. PATIENTS: Patients with an ileal pouch prior to ileostomy closure (n = 12), functioning pouch (n = 14), pouchitis (n = 8), and ulcerative colitis (n = 12) were assessed. METHODS: 51Cr-EDTA was administered into the 'pouch' or rectum and urinary recovery over 24 hours was taken as an indication of permeability (barrier function). Histological analysis of 'pouch' biopsy specimens was undertaken. RESULTS: Mucosal permeability is decreased from median 9.4% (range 5.4% to 39.1%) to 1.4% (range 0.38% to 2.2%) after ileostomy closure (p < 0.002) with levels being negatively correlated with two histological parameters of colonic metaplasia-mucin changes (p = 0.03) and villous atrophy (p = 0.05). Pouchitis was associated with increased permeability 5.9% (1.9% to 19.5%) compared with healthy 'pouch' 1.4% (0.35 to 2.2%) (p < 0.006). CONCLUSION: Despite the presence of chronic inflammation in the mature 'pouch' functional adaptation with reduced permeability occurs in conjunction with colonic metaplasia. PMID:8991861

Merrett, M N; Soper, N; Mortensen, N; Jewell, D P

1996-01-01

401

Permeability of granite in a temperature gradient  

Microsoft Academic Search

Changes in permeability of granite were measured as water flowed through samples in a temperature gradient. The experimental conditions simulated those around the 'very deep hole concept' nuclear waste repository. Temperature was maintained between 200° and 310°C, in a borehole of a cylindrical sample. Confining pressures of 30 and 60 MPa, with corresponding pore pressures of 10 and 20 MPa,

C. Morrow; D. Lockner; D. Moore; J. Byerlee

1981-01-01

402

Permeable Pavements, Green Roofs, and Cisterns  

E-print Network

examples of appropriate uses for permeable pavements include patios, residential parking pads, driveways opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, fire lanes, overflow parking areas, and some daily parking areas. For runoff reduction, a per- meable

Hunt, William F.

403

Reduced hydrogen permeability at high temperatures  

NASA Technical Reports Server (NTRS)

CO and CO2 reduce hydrogen loss through iron, nickel, and cobalt based alloy tubes. Method is based on concept that oxide film on metal surface reduces hydrogen permeability through metal; adding CO or CO2 forms oxide films continuously during operation, and hydrogen containment is improved. Innovation enhances prospects for Stirling engine system utilization.

Stephens, J. R.; Klopp, W. D.; Misencik, J. A.

1981-01-01

404

Testosterone Perturbs Epidermal Permeability Barrier Homeostasis  

Microsoft Academic Search

Although there are no known gender-related differences in permeability barrier function in adults, estrogens accelerate whereas testosterone retards barrier development in fetal skin, and male fetuses demonstrate slower barrier development than female littermates. Moreover, prenatal administration of the androgen receptor antagonist, flutamide, equalizes developmental rates in male and female fetuses. Therefore, we evaluated the effects of changes in testosterone on

Jack S. Kao; Amit Garg; Man Mao-Qiang; Debra Crumrine; Ruby Ghadially; Kenneth R. Feingold; Peter M. Elias

2001-01-01

405

Hydromechanical scraper helps plug permeable zones  

Microsoft Academic Search

A simple downhole tool, which resembles a scraper with side jets, uses mechanical action and hydraulics to plug permeable, water-bearing formations that may cause cementing problems. The tool has also shown promise in curing lost circulation zones when used with fine, dispersed fillers. The producing life of an oil well often depends on casing cement quality. The casing and cement

Kurochkin

1995-01-01

406

EFFECT OF X RADIATION ON CELL PERMEABILITY  

Microsoft Academic Search

A study was made of the effect of a single dose of 1000 r of x rays on ; the cell permeability in epidermal cells of a variety of Vsetaty onion (Allium ; cepa), by means of a plasmolytic method. For plasmolysis, M sucrose and 0.64 M ; KNOâ solutions of pH 5 were used. In comparison with the controls,

B. Hluchovsky; V. Srb

1961-01-01

407

Permeable pavement research ? Edison, New Jersey  

EPA Science Inventory

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

408

Estimating Plastic Film Permeability Under Field Conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fumigant emission is an important air quality and human health concern. Plastic films are used to reduce emissions. Laboratory tests have shown large differences in permeability between various films, including the typical polyethylene films (PEs), virtually impermeable films (VIFs), and semi-impe...

409

Anisotropic Permeability of a Strike Slip Fault  

NASA Astrophysics Data System (ADS)

Pump tests were performed in isolated sections of two inclined ~200m long boreholes that are ~130 meters apart from each other (WF-4 and WF-5 in Figure 1). The boreholes penetrate the Wildcat Fault, a semi-vertical strike slip fault, which is a member of the Hayward Fault system situated in the Berkeley Hills. The geology encountered in the boreholes was predominantly the Claremont Fm., extensively fractured and alternating sequences of chert, shale and sandstone. The drawdowns in four isolated sections in a vertical borehole (WF-1) drilled adjacent to the fault at distances of ~45m and ~95m from each of the inclined borehole was analyzed. The permeability of the fault plane was found to be two orders of magnitude higher than that of the protolith and anisotropic with approximately 10 fold higher permeability in near horizontal direction, which is somewhat expected for a strike slip fault (Figure 2). Build-up analysis suggests that the fault is asymmetric with higher permeability along the east side of the fault plane and lower along the west side.igure 1. Pumping test configuration with two inclined boreholes (WF-4 and WF-5) intersecting the Wildcat Fault. The vertical borehole WF-1 is situated very close to the fault. igure 2. Dimensionless directional drawdowns observed in four isolated sections in WF-1 in response to the pumping in WF-4 and WF-5 at a dimensionless time of 16. Also shown is the best fit permeability ellipse.

Karasaki, K.; Goto, J.; Kiho, K.

2012-12-01

410

Hydrogen Permeability and Integrity of Hydrogen  

E-print Network

Hydrogen Permeability and Integrity of Hydrogen Delivery Pipelines Z. Feng*, L.M. Anovitz*, J and industry expectations · DOE Pipeline Working Group and Tech Team activities - FRP Hydrogen Pipelines - Materials Solutions for Hydrogen Delivery in Pipelines - Natural Gas Pipelines for Hydrogen Use #12;3 OAK

411

Intestinal permeability is decreased in anorexia nervosa  

Microsoft Academic Search

Malnutrition and absence of exogenous luminal nutrients in the gastrointestinal tract affect intestinal permeability (IP) leading to an increased penetration of substances that passively cross intestinal epithelium via intercellular pathways. We hypothesised that an increase in IP could occur in patients with anorexia nervosa because of their prolonged fasting and chronic malnutrition. Therefore, we assessed IP in 14 drug-free anorexic

P Monteleone; R Carratù; M Cartenì; M Generoso; M Lamberti; L De Magistris; F Brambilla; B Colurcio; M Secondulfo; M Maj

2004-01-01

412

New network permeability model of porous media  

Microsoft Academic Search

In this study a new mathematical model for predicting permeabilities of porous media has been developed. The model consists of a set of cubic networks of arbitrary orientations with respect to the macroscopic flow direction. The networks consist of capillary tubes which are made up of segments of different diameters. It is shown that a cubic network of capillaries has

Francis A. L. Dullien

1975-01-01

413

PRECISION AND RELIABILITY OF LABORATORY PERMEABILITY MEASUREMENTS  

EPA Science Inventory

A limited set of laboratory test data on clay liner permeabilities was gathered from six sources to create a data bank suitable for a preliminary statistical analysis. The collected data were also used to survey the most commonly used permeameters and testing methods for clay lin...

414

Waveguide miniaturization using uniaxial negative permeability metamaterial  

Microsoft Academic Search

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

Silvio Hrabar; Juraj Bartolic; Zvonimir Sipus

2005-01-01

415

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, ...

416

Permeable reactive barrier for groundwater remediation  

Microsoft Academic Search

This article aims to provide an overview of the upcoming technology of permeable reactive barriers for groundwater remediation. A comprehensive list of references and web-links are also provided for further in-depth understanding. A brief discussion on the Australian perspective on this emerging technology is also included.

R. Thiruvenkatachari; S. Vigneswaran; R. Naidu

2008-01-01

417

Hydrogeologic modeling for permeable reactive barriers  

Microsoft Academic Search

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

Neeraj Gupta; Tad C Fox

1999-01-01

418

Probabilistic Design of Permeable Reactive Barriers  

Microsoft Academic Search

Deterministic design procedures, while adequate for feasibility evaluation, are not sufficient for final design of iron permeable reactive barriers (PRBs). A probabilistic design methodology is outlined, which incorporates not only probabilistic inputs for site characterization data, but also parent and daughter VOC degradation parameters. A multi-specie first order volatile organic compound (VOC) degradation model coupled with a probabilistic model is

Grant Hocking; Samuel L. Wells; Rafael I. Ospina; Golder Sierra; LLC Atlanta

419

Geochemistry and Performance of Permeable Reactive Barriers  

Microsoft Academic Search

The application of permeable reactive barrier (PRB) systems for treatment of contaminated groundwater has increased progressively over the past ten years. Since the initial installations in the early 1990's many PRB systems containing zero valent iron have functioned as designed. Treatment levels that do not meet design objectives are generally attributable to discrepancies between predicted and observed contaminant distribution and

D. Blowes; C. J. Ptacek; D. J. Smyth

2001-01-01

420

The diffusion-active permeable reactive barrier  

Microsoft Academic Search

Using the biogeochemical model CCBATCH, which we expanded to include transport processes, we study a novel approach for the treatment of aquifers contaminated with toxic concentrations of metals, the diffusion-active permeable reactive barrier (DAPRB), which is based on generation of sulfide by Sulfate Reducing Bacteria (SRB) as the groundwater moves through a layered treatment zone. In the DAPRB, layers of

Alex O. Schwarz; Bruce E. Rittmann

2010-01-01

421

A COMPARATIVE STUDY OF PERMEABILITY IN PLANTS  

PubMed Central

Quantitative studies on Laminaria (a brown alga), Ulva (a green alga), Rhodymenia (a red alga), and Zostera (a flowering plant) show that the behavior of these plants, in respect to changes in permeability, is essentially alike in all cases. PMID:19871746

Osterhout, W. J. V.

1919-01-01

422

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...

423

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