Sample records for vascular permeability index

  1. Vascular permeability, vascular hyperpermeability and angiogenesis

    PubMed Central

    Nagy, Janice A.; Benjamin, Laura; Zeng, Huiyan; Dvorak, Ann M.

    2008-01-01

    The vascular system has the critical function of supplying tissues with nutrients and clearing waste products. To accomplish these goals, the vasculature must be sufficiently permeable to allow the free, bidirectional passage of small molecules and gases and, to a lesser extent, of plasma proteins. Physiologists and many vascular biologists differ as to the definition of vascular permeability and the proper methodology for its measurement. We review these conflicting views, finding that both provide useful but complementary information. Vascular permeability by any measure is dramatically increased in acute and chronic inflammation, cancer, and wound healing. This hyperpermeability is mediated by acute or chronic exposure to vascular permeabilizing agents, particularly vascular permeability factor/vascular endothelial growth factor (VPF/VEGF, VEGF-A). We demonstrate that three distinctly different types of vascular permeability can be distinguished, based on the different types of microvessels involved, the composition of the extravasate, and the anatomic pathways by which molecules of different size cross-vascular endothelium. These are the basal vascular permeability (BVP) of normal tissues, the acute vascular hyperpermeability (AVH) that occurs in response to a single, brief exposure to VEGF-A or other vascular permeabilizing agents, and the chronic vascular hyperpermeability (CVH) that characterizes pathological angiogenesis. Finally, we list the numerous (at least 25) gene products that different authors have found to affect vascular permeability in variously engineered mice and classify them with respect to their participation, as far as possible, in BVP, AVH and CVH. Further work will be required to elucidate the signaling pathways by which each of these molecules, and others likely to be discovered, mediate the different types of vascular permeability. PMID:18293091

  2. Tonic regulation of vascular permeability

    PubMed Central

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

    2014-01-01

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

  3. THE GRADIENT OF VASCULAR PERMEABILITY

    PubMed Central

    Rous, Peyton; Gilding, H. P.; Smith, Frederick

    1930-01-01

    The permeability of the capillaries in the skeletal muscles of mammals increases progressively along their course and is greatest where they pass into the least venules. The gradient of permeability is so largely independent of functional states as to give grounds for the view that it is determined by inherent local differences. Through the gradient opportunity is equalized along the capillary. In the liver lobule this object is accomplished by an artifice of arrangement whereby the blood flow past the cells is increased with their distance from the source of supply. In the urinary bladder the interlacing of capillaries, their progressive widening, and a consequent gradual slowing of the blood flow act to achieve the same end. Here a gradient of permeability has not been demonstrable. Where cells of different sorts are served by a slender capillary, their differing requirements may render unnecessary any provision to equalize their opportunities; but where shortcomings in local maintenance will reduce the efficiency of an entire fabric, as the muscle fibre, and where cells of like character live competitively along the same channel, as in the liver, some arrangement must exist to ensure an even distribution of the services rendered by the blood. In situations of the kind last mentioned the immediate environment of the individual cell, the "milieu interne" of Bernard, is not only kept as constant as possible but it must be the same, by and large, for all of the cells. The task of serving voluntary muscle is not strictly limited to the capillaries. The intrafascicular arterioles and venules act so effectively to sustain the tissue about them that where they run no capillaries are supplied. PMID:19869729

  4. Ocular neovascularisation and excessive vascular permeability.

    PubMed

    Campochiaro, Peter A

    2004-09-01

    Diseases complicated by vascular leakage and/or neovascularisation in the eye are responsible for the vast majority of visual morbidity and blindness in developed countries. The molecular signals that control vascular permeability and neovascularisation in the eye are being defined. Members of the vascular endothelial growth factor (VEGF) family are key stimulators that interact with two tyrosine kinase receptors, VEGF receptor (VEGFR)1 and 2; binding to two other receptors that lack tyrosine kinase activity, the neuropilins, is also important. Signalling through the VEGF pathway is modulated by the Tie2 receptor and its binding partners, the angiopoietins. Each of the participants in these two signalling pathways provides a potential target for intervention. Several proteins with antiangiogenic activity balance the stimulators and the outcome is determined by the net balance. Endostatin suppresses vascular permeability as well as ocular neovascularisation, suggesting that vascular leakage may also be regulated by counteracting proteins. Gene transfer provides a useful way to influence these balances. Clinical trials are underway to test whether these mechanisms can be translated into new therapies. PMID:15335307

  5. Control of vascular permeability by adhesion molecules.

    PubMed

    Sarelius, Ingrid H; Glading, Angela J

    2015-01-01

    Vascular permeability is a vital function of the circulatory system that is regulated in large part by the limited flux of solutes, water, and cells through the endothelial cell layer. One major pathway through this barrier is via the inter-endothelial junction, which is driven by the regulation of cadherin-based adhesions. The endothelium also forms attachments with surrounding proteins and cells via 2 classes of adhesion molecules, the integrins and IgCAMs. Integrins and IgCAMs propagate activation of multiple downstream signals that potentially impact cadherin adhesion. Here we discuss the known contributions of integrin and IgCAM signaling to the regulation of cadherin adhesion stability, endothelial barrier function, and vascular permeability. Emphasis is placed on known and prospective crosstalk signaling mechanisms between integrins, the IgCAMs- ICAM-1 and PECAM-1, and inter-endothelial cadherin adhesions, as potential strategic signaling nodes for multipartite regulation of cadherin adhesion. PMID:25838987

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

    Microsoft Academic Search

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

    1994-01-01

    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

  7. Brief Communication Determination of vascular permeability coefficients under slow

    E-print Network

    Tien, Joe

    (permeability coefficient normalized by vascular dimensions) from time-lapse intensity data for which, a labeled (e.g., fluorescent) solute is introduced abruptly into the vascular space at a concentration (Chrobak et al., 2006). In these cases, the solute will disperse axially as it travels from the site

  8. Soluble neuropilin targeted to the skin inhibits vascular permeability

    Microsoft Academic Search

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

    2005-01-01

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

  9. Vascular permeability factor (VPF, VEGF) in tumor biology

    Microsoft Academic Search

    Donald R. Senger; Livingston Van De Water; Lawrence F. Brown; Janice A. Nagy; Kiang-Teck Yeo; Tet-Kin Yeo; Brygida Berse; Robert W. Jackman; Ann M. Dvorak; Harold F. Dvorak

    1993-01-01

    Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a multifunctional cytokine expressed and secreted at high levels by many tumor cells of animal and human origin. As secreted by tumor cells, VPF\\/VEGF is a 34–42 kDa heparin-binding, dimeric, disulfide-bonded glycoprotein that acts directly on endothelial cells (EC) by way of specific receptors to activate phospholipase

  10. Vascular Permeability Factor\\/Vascular Endothelial Growth Factor Induces Lymphangiogenesis as well as Angiogenesis

    Microsoft Academic Search

    Janice A. Nagy; Eliza Vasile; Dian Feng; Christian Sundberg; Lawrence F. Brown; Michael J. Detmar; Joel A. Lawitts; Laura Benjamin; Xiaolian Tan; Eleanor J. Manseau; Ann M. Dvorak; Harold F. Dvorak

    2002-01-01

    Vascular permeability factor\\/vascular endothelial growth factor (VPF\\/VEGF, VEGF-A) is a multifunctional cytokine with important roles in pathological angiogenesis. Using an adeno- viral vector engineered to express murine VEGF-A 164 , we previously investigated the steps and mechanisms by which this cytokine induced the formation of new blood vessels in adult immu- nodeficient mice and demonstrated that the newly formed blood

  11. Neuropilin regulation of angiogenesis, arteriogenesis, and vascular permeability.

    PubMed

    Plein, Alice; Fantin, Alessandro; Ruhrberg, Christiana

    2014-05-01

    The formation of the cardiovasculature, consisting of both the heart and blood vessels, is a critical step in embryonic development and relies on three processes termed vasculogenesis, angiogenesis, and vascular remodeling. The transmembrane protein NRP1 is an essential modulator of embryonic angiogenesis with additional roles in vessel remodeling and arteriogenesis. NRP1 also enhances arteriogenesis in adults to alleviate pathological tissue ischemia. However, in certain circumstances, vascular NRP1 signaling can be detrimental, as it may promote cancer by enhancing tumor angiogenesis or contribute to tissue edema by increasing vascular permeability. Understanding the mechanisms of NRP1 signaling is, therefore, of profound importance for the design of therapies aiming to control vascular functions. Previous work has shown that vascular NRP1 can variably serve as a receptor for two secreted glycoproteins, the VEGF-A and SEMA3A, but it also has a poorly understood role as an adhesion receptor. Here, we review current knowledge of NRP1 function during blood vessel growth and homeostasis, with special emphasis on the vascular roles of its multiple ligands and signaling partners. PMID:24521511

  12. Effect of leukotriene receptor antagonists on vascular permeability during endotoxic shock

    SciTech Connect

    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

    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.

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

    PubMed Central

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

    2001-01-01

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

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

    PubMed Central

    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

    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

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

    PubMed Central

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

    2015-01-01

    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

  16. Keratinocyte-Derived Vascular Permeability Factor (Vascular Endothelial Growth Factor) Is a Potent Mitogen for Dermal Microvascular Endothelial Cells

    Microsoft Academic Search

    Michael Detmar; Kiang-Teck Yeo; Janice A. Nagy; Livingston van de Water; Lawrence F. Brown; Brygida Berse; Brett M. Elicker; Stephen Ledbetter; Harold F. Dvorak

    1995-01-01

    Expression of vascular permeability factor\\/vascular endothelial growth factor (VPF\\/VEGF) is markedly increased in the epidermis of lesional psoriatic skin and in healing skin wounds. In this study, we characterized the effects of several cytokines and growth factors on the expression and secretion of VPF\\/VEGF mRNA and protein by cultured human epidermal keratinocytes, as well as the effect of VPF\\/VEGF on

  17. Effects of polycations on pulmonary vascular permeability in conscious sheep.

    PubMed Central

    Toyofuku, T; Koyama, S; Kobayashi, T; Kusama, S; Ueda, G

    1989-01-01

    The role of charged sites on the permeability characteristics of the pulmonary microvascular barrier were investigated using chronically instrumented unanesthetized sheep. In one series of experiments we studied the effects of the cationic amphiphile, dodecyl trimethylamine (DTA; 297 mol wt), and the anionic amphiphile, SDS (288 mol wt), on lung lymph flow rates (Ql), lung lymph to plasma protein ratios (L/P), pulmonary hemodynamics, and systemic hemodynamics. DTA significantly increased both Ql and L/P, whereas SDS had a more modest and transient effect on these variables. In a second series of experiments the polycations polybrene and poly-l-lysine were found to have very similar effects as those of DTA. In another series of experiments we tested the pretreatment inhibition potential of chlorpheniramine (an H1 receptor antagonist), dibutyryl-cyclic AMP (db-cAMP), and the calcium channel antagonists verapamil and nifedipine on polybrene-induced lung injury. We found that only verapamil and db-cAMP significantly attenuated the permeability effects of polybrene. We conclude that both cationic amphiphiles and polycations cause hemodynamic and permeability alterations in the pulmonary circulation of unanesthetized sheep. In addition, the permeability alterations induced by polybrene can be modulated by intracellular calcium and/or cAMP levels. PMID:2542380

  18. Vascular permeability activity in Escherichia coli heat-stable enterotoxin.

    PubMed

    Craig, J P; Yamamoto, K; Takeda, T; Takeda, Y; Miwatani, T

    1981-08-01

    Purified heat-stable enterotoxin (ST) prepared from supernatants of Escherichia coli strain 53402 A-1, isolated from a patient with diarrhea, caused an increase in the permeability of the small blood vessels of the skin of adult rabbits after intracutaneous injection. Increased permeability was manifested by localized accumulation of intravenously injected blue dye at the injection sites. Permeability factor (PF) activity reached a peak 1 h after injection, and recovery of normal permeability was nearly complete in 3 h. Residual PF activity had disappeared by 24 h. Dose-response curves demonstrated a straight-line relationship between the logarithm of the dose and mean blueing diameter over a range of 3 to 12 mm. The PF assay was less sensitive that the suckling mouse assay, and adult rabbits varied in their sensitivity to the PF effect. Five to 100 mouse units of ST were required to consistently evoke strong and unequivocal blue lesions of 7 mm or more in diameter. PF activity was reduced 50 to 70% by heating at 70 degrees C for 30 min, 60 to 80% by boiling for 30 min, and 95 to 98% by autoclaving for 15 min, but it was unaffected by treatment with cholera antitoxin. These findings are consistent with the notion that PF activity is a property of the ST molecule itself. This PF assay cannot be used for the detection of ST in crude culture supernatant fluid because of low sensitivity and the presence of nonspecific PF effects of culture media and other E. coli products. PMID:7196884

  19. Endothelial Domes Encapsulate Adherent Neutrophils and Minimize Increases in Vascular Permeability in Paracellular and Transcellular Emigration

    PubMed Central

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

    2008-01-01

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

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

    PubMed Central

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

    2013-01-01

    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

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

    PubMed

    Morita, Shoko; Miyata, Seiji

    2012-08-01

    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

  2. Further experience with the index metacarpal vascularized bone graft

    Microsoft Academic Search

    C. Mathoulin; F. Brunelli

    1998-01-01

    We report our experience in the use of a vascularized bone graft harvested from the head of the index metacarpal to treat scaphoid nonunion after failure of other techniques. Only 15 patients were treated between 1988 and 1994, showing the scarcity of indications for the operation. Union was obtained in 14 cases but the functional results were acceptable in ten

  3. Neuropilin-1 Regulates Vascular Endothelial Growth Factor-Mediated Endothelial Permeability

    Microsoft Academic Search

    Patrice M. Becker; Johannes Waltenberger; Robin Yachechko; Tamara Mirzapoiazova; James S. K. Sham; Chun Geun Lee; Jack A. Elias; Alexander D. Verin

    2007-01-01

    Neuropilin-1 (Npn-1) is a cell surface receptor that binds vascular endothelial growth factor (VEGF), a potent mediator of endothelial permeability, chemotaxis, and proliferation. In vitro, Npn-1 can complex with VEGF receptor-2 (VEGFR2) to enhance VEGFR2-mediated endothelial cell chemotaxis and proliferation. To determine the role of Npn-1\\/VEGFR2 complexes in VEGF-induced endothelial barrier dysfunction, endothelial cells were stably transfected with Npn1 or

  4. Overexpression of Vascular Endothelial Growth Factor in the Avian Embryo Induces Hypervascularization and Increased Vascular Permeability without Alterations of Embryonic Pattern Formation

    Microsoft Academic Search

    Ingo Flamme; Marie von Reutern; Hannes C. A. Drexler; Sarwar Syed-Ali; Werner Risau

    1995-01-01

    Vascular endothelial growth factor (VEGF)—also known as vascular permeability factor—has been implicated in the regulation of blood vessel formation, i.e., vasculogenesis and angiogenesis. High amounts of VEGF mRNA and protein have been detected during embryonic and tumor angiogenesis, but it remained unclear whether the level of VEGF correlated with the extent of vascularization in a given organ or tissue. We

  5. Modulation of VEGF-Induced Retinal Vascular Permeability by Peroxisome Proliferator-Activated Receptor-?/?

    PubMed Central

    Suarez, Sandra; McCollum, Gary W.; Bretz, Colin A.; Yang, Rong; Capozzi, Megan E.; Penn, John S.

    2014-01-01

    Purpose. Vascular endothelial growth factor (VEGF)-induced retinal vascular permeability contributes to diabetic macular edema (DME), a serious vision-threatening condition. Peroxisome proliferator-activated receptor ?/? (PPAR?/?) antagonist/reverse agonist, GSK0660, inhibits VEGF-induced human retinal microvascular endothelial cell (HRMEC) proliferation, tubulogenesis, and oxygen-induced retinal vasculopathy in newborn rats. These VEGF-induced HRMEC behaviors and VEGF-induced disruption of endothelial cell junctional complexes may well share molecular signaling events. Thus, we sought to examine the role of PPAR?/? in VEGF-induced retinal hyperpermeability. Methods. Transendothelial electrical resistance (TEER) measurements were performed on HRMEC monolayers to assess permeability. Claudin-1/Claudin-5 localization in HRMEC monolayers was determined by immunocytochemistry. Extracellular signal-regulated protein kinases 1 and 2 (Erk 1/2) phosphorylation, VEGF receptor 1 (VEGFR1) and R2 were assayed by Western blot analysis. Expression of VEGFR1 and R2 was measured by quantitative RT-PCR. Last, retinal vascular permeability was assayed in vivo by Evans blue extravasation. Results. Human retinal microvascular endothelial cell monolayers treated with VEGF for 24 hours showed decreased TEER values that were completely reversed by the highest concentration of GSK0660 (10 ?M) and PPAR?/?-directed siRNA (20 ?M). In HRMEC treated with VEGF, GSK0660 stabilized tight-junctions as evidenced by Claudin-1 staining, reduced phosphorylation of Erk1/2, and reduced VEGFR1/2 expression. Peroxisome proliferator-activated receptor ?/? siRNA had a similar effect on VEGFR expression and Claudin-1, supporting the specificity of GSK0660 in our experiments. Last, GSK0660 significantly inhibited VEGF-induced retinal vascular permeability and reduced retinal VEGFR1and R2 levels in C57BL/6 mice. Conclusions. These data suggest a protective effect for PPAR?/? antagonism against VEGF-induced vascular permeability, possibly through reduced VEGFR expression. Therefore, antagonism/reverse agonism of PPAR?/? siRNA may represent a novel therapeutic methodology against retinal hyperpermeability and is worthy of future investigation. PMID:25406289

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

    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.

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

    SciTech Connect

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

    1981-01-01

    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.

  8. Cadmium induces vascular permeability via activation of the p38 MAPK pathway.

    PubMed

    Dong, Fengyun; Guo, Fang; Li, Liqun; Guo, Ling; Hou, Yinglong; Hao, Enkui; Yan, Suhua; Allen, Thaddeus D; Liu, Ju

    2014-07-18

    The vasculature of various organs is a targeted by the environmental toxin, cadmium (Cd). However, mechanisms leading to pathological conditions are poorly understood. In the present study, we examined the effect of cadmium chloride (CdCl2) on human umbilical vein endothelial cells (HUVECs). At 4 ?M, CdCl2 induced a hyper-permeability defect in HUVECs, but not the inhibition of cell growth up to 24h. This effect of CdCl2 was dependent on the activation of the p38 mitogen-activated protein kinase (MAPK) pathway. The p38 MAPK inhibitor SB203850 suppressed the CdCl2-induced alteration in trans-endothelial electrical resistance in HUVEC monolayers, a model measurement of vascular endothelial barrier integrity. SB203850 also inhibited the Cd-induced membrane dissociation of vascular endothelial (VE) cadherin and ?-catenin, the important components of the adherens junctional complex. In addition, SB203850 reduces the Cd-induced expression and secretion of tumor necrosis factor ? (TNF-?). Taken together, our findings suggest that Cd induces vascular hyper-permeability and disruption of endothelial barrier integrity through stimulation of p38 MAPK signaling. PMID:24909688

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed Central

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

    2013-01-01

    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

  11. Neuropilin-1 regulates vascular endothelial growth factor-mediated endothelial permeability.

    PubMed

    Becker, Patrice M; Waltenberger, Johannes; Yachechko, Robin; Mirzapoiazova, Tamara; Sham, James S K; Lee, Chun Geun; Elias, Jack A; Verin, Alexander D

    2005-06-24

    Neuropilin-1 (Npn-1) is a cell surface receptor that binds vascular endothelial growth factor (VEGF), a potent mediator of endothelial permeability, chemotaxis, and proliferation. In vitro, Npn-1 can complex with VEGF receptor-2 (VEGFR2) to enhance VEGFR2-mediated endothelial cell chemotaxis and proliferation. To determine the role of Npn-1/VEGFR2 complexes in VEGF-induced endothelial barrier dysfunction, endothelial cells were stably transfected with Npn1 or VEGFR2 alone (PAE/Npn and PAE/KDR, respectively), or VEGFR2 and Npn-1 (PAE/KDR/Npn-1). Permeability, estimated by measurement of transendothelial electrical resistance (TER), of PAE/Npn and PAE/KDR cell lines was not altered by VEGF165. In contrast, TER of PAE/KDR/Npn-1 cells decreased in dose-dependent fashion following VEGF165 (10 to 200 ng/mL). Activation of VEGFR2, and 2 downstream signaling intermediates (p38 and ERK1/2 MAPK) involved in VEGF-mediated permeability, also increased in PAE/KDR/Npn-1. Consistent with these data, inhibition of Npn-1, but not VEGFR2, attenuated VEGF165-mediated permeability of human pulmonary artery endothelial cells (HPAE), and VEGF121 (which cannot ligate Npn-1) did not alter TER of HPAE. Npn-1 inhibition also attenuated both VEGF165-mediated pulmonary vascular leak and activation of VEGFR2, p38, and ERK1/2 MAPK, in inducible lung-specific VEGF transgenic mice. These data support a critical role for Npn-1 in regulating endothelial barrier dysfunction in response to VEGF and suggest that activation of distinct receptor complexes may determine specificity of cellular response to VEGF. PMID:15920019

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

    PubMed

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

    2011-06-01

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

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

    SciTech Connect

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

    1986-07-01

    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.

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

    PubMed Central

    2013-01-01

    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

  15. Regulation of Placental Vascular Endothelial Growth\\/ Permeability Factor Expression and Angiogenesis by Estrogen during Early Baboon Pregnancy

    Microsoft Academic Search

    EUGENE D. ALBRECHT; VICTORIA A. ROBB; GERALD J. PEPE

    We have recently shown that there was a developmental in- crease in placental trophoblast vascular endothelial growth\\/ permeability factor (VEG\\/PF) expression and vascularization that closely paralleled maternal serum estrogen levels during advancing baboon gestation. The present study determined whether estrogen regulates these important aspects of pri- mate development. VEG\\/PF mRNA levels were determined by competitive RT-PCR in isolated villous placental

  16. Mast Cells Can Secrete Vascular Permeability Factor/ Vascular Endothelial Cell Growth Factor and Exhibit Enhanced Release after Immunoglobulin E–dependent Upregulation of Fc? Receptor I Expression

    PubMed Central

    Boesiger, Jürg; Tsai, Mindy; Maurer, Marcus; Yamaguchi, Masao; Brown, Lawrence F.; Claffey, Kevin P.; Dvorak, Harold F.; Galli, Stephen J.

    1998-01-01

    Vascular permeability factor/vascular endothelial cell growth factor (VPF/VEGF) can both potently enhance vascular permeability and induce proliferation of vascular endothelial cells. We report here that mouse or human mast cells can produce and secrete VPF/VEGF. Mouse mast cells release VPF/VEGF upon stimulation through Fc? receptor I (Fc?RI) or c-kit, or after challenge with the protein kinase C activator, phorbol myristate acetate, or the calcium ionophore, A23187; such mast cells can rapidly release VPF/VEGF, apparently from a preformed pool, and can then sustain release by secreting newly synthesized protein. Notably, the Fc?RI-dependent secretion of VPF/VEGF by either mouse or human mast cells can be significantly increased in cells which have undergone upregulation of Fc?RI surface expression by a 4-d preincubation with immunoglobulin E. These findings establish that at least one cell type, the mast cell, can be stimulated to secrete VPF/VEGF upon immunologically specific activation via a member of the multichain immune recognition receptor family. Our observations also identify a new mechanism by which mast cells can contribute to enhanced vascular permeability and/or angiogenesis, in both allergic diseases and other settings. PMID:9743532

  17. The effects of polycations on vascular permeability in the rat. A proposed role for charge sites.

    PubMed Central

    Vehaskari, V M; Chang, C T; Stevens, J K; Robson, A M

    1984-01-01

    This study investigated whether charge sites in the walls of the microvasculature may play a role in maintaining the impermeability of the nonrenal capillaries to albumin. All experiments were performed in nephrectomized rats, studied in the awake state. The intravenous injection of protamine sulfate (4 mg/100 g body wt dissolved in 0.9% saline) was followed by a mean increase of 29.1% in hematocrit and a decrease of 28.4% in plasma albumin concentration over a 10-min period, indicating a significant 50-60% loss of albumin from the vascular space; a finding confirmed by studies using exogenous 125I-labeled albumin. Changes persisted for the remaining 80 min of observation, and could be reproduced by the injection of two other polycations, hexadimethrine and poly-l-lysine. These effects were not prevented by the antihistamine diphenhydramine hydrochloride. In contrast to 125I-labeled albumin, 14C-labeled neutral dextran of comparable size was not confined to the vascular space; its apparent volume of distribution progressively increased during the 90 min of observation. Intravenous injection of protamine sulfate was followed by a significantly smaller loss of 14C-dextran (36.5%) than albumin (59.1%) from the vascular space (P less than 0.01). Protamine sulfate could not be demonstrated to result in any changes in the physicochemical characteristics of albumin. These observations suggest that the negative charge sites present in nonglomerular capillary walls have functions similar to equivalent sites present in the glomerular capillaries. Thus, charge sites could contribute to the low permeability of the microvasculature to negatively charged macromolecules such as albumin. This may be an important mechanism for retaining albumin in the vascular space and preventing edema formation in health. PMID:6200500

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

    PubMed Central

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

    2014-01-01

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

  19. The diaphragms of fenestrated endothelia – gatekeepers of vascular permeability and blood composition

    PubMed Central

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

    2012-01-01

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

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

    PubMed Central

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

    2014-01-01

    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

  1. Neurogenic inflammation in the rat trachea. II. Identity and distribution of nerves mediating the increase in vascular permeability

    Microsoft Academic Search

    Donald M. McDonald; Robert A. Mitchell; Giorgio Gabella; Amy Haskell

    1988-01-01

    Summary This study addresses the question of whether increased vascular permeability, which is a prominent feature of neurogenic inflammation in the respiratory tract, is mediated by sensory axons that end near venules in the airway mucosa. In these experiments, neurogenic inflammation was produced in the tracheal and bronchial mucosa of atropine-treated Long-Evans rats by electrical stimulation of the left or

  2. Stress-induced dura vascular permeability does not develop in mast cell-deficient and neurokinin-1 receptor knockout mice

    Microsoft Academic Search

    Kristiana Kandere-Grzybowska; Daniela Gheorghe; Josef Priller; Pamela Esposito; Man Huang; Norma Gerard; Theoharis C. Theoharides

    2003-01-01

    Migraine headaches are often precipitated by stress and seem to involve neurogenic inflammation (NI) of the dura mater associated with the sensation of throbbing pain. Trigeminal nerve stimulation had been reported to activate rat dura mast cells and increase vascular permeability, effects inhibited by neonatal pretreatment with capsaicin implicating sensory neuropeptides, such as substance P (SP). The aim of the

  3. PEDF improves cardiac function in rats with acute myocardial infarction via inhibiting vascular permeability and cardiomyocyte apoptosis.

    PubMed

    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

    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

  4. Vascular permeability in experimental diabetes is associated with reduced endothelial occludin content: vascular endothelial growth factor decreases occludin in retinal endothelial cells. Penn State Retina Research Group.

    PubMed

    Antonetti, D A; Barber, A J; Khin, S; Lieth, E; Tarbell, J M; Gardner, T W

    1998-12-01

    Blood-retinal barrier (BRB) breakdown is a hallmark of diabetic retinopathy, but the molecular changes that cause this pathology are unclear. Occludin is a transmembrane component of interendothelial tight junctions that may regulate permeability at the BRB. In this study, we examined the effects of vascular endothelial growth factor (VEGF) and diabetes on vascular occludin content and barrier function. Sprague-Dawley rats were made diabetic by intravenous streptozotocin injection, and age-matched animals served as controls. After 3 months, BRB permeability was quantified by intravenous injection of fluorescein isothiocyanate-bovine serum albumin (FITC-BSA), Mr 66 kDa, and 10-kDa rhodamine-dextran (R-D), followed by digital image analysis of retinal sections. Retinal fluorescence intensity for FITC-BSA increased 62% (P < or = 0.05), but R-D fluorescence did not change significantly. Occludin localization at interendothelial junctions was confirmed by immunofluorescence, and relative protein content was determined by immunoblotting of retinal homogenates. Retinal occludin content decreased approximately 35% (P < or = 0.03) in the diabetic versus the control animals, whereas the glucose transporter GLUT1 content was unchanged in rat retinas. Additionally, treatment of bovine retinal endothelial cells in culture with 0.12 nmol/l or 12 nmol/l VEGF for 6 h reduced occludin content 46 and 54%, respectively. These data show that diabetes selectively reduces retinal occludin protein expression and increases BRB permeability. Our findings suggest that the elevated VEGF in the vitreous of patients with diabetic retinopathy increases vascular permeability by downregulating occludin content. Decreased tight junction protein expression may be an important means by which diabetes causes increased vascular permeability and contributes to macular edema. PMID:9836530

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

    PubMed Central

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

    2014-01-01

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

  6. Vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in normal and atherosclerotic human arteries.

    PubMed Central

    Couffinhal, T.; Kearney, M.; Witzenbichler, B.; Chen, D.; Murohara, T.; Losordo, D. W.; Symes, J.; Isner, J. M.

    1997-01-01

    Vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) is an endothelial-cell-specific mitogen; as such, its role in angiogenesis has been studied extensively. VEGF/VPF may also serve as a local, endogenous regulator of large-vessel endothelial cell integrity. Surprisingly, however, VEGF/VPF expression in normal and/or atherosclerotic vessels has not been previously characterized. Accordingly, we studied normal human arteries and veins as well as atherosclerotic and restenotic human coronary arteries for evidence of VEGF/VPF expression. VEGF/VPF was detected immunohistochemically in sections of normal human aorta, mammary artery, and saphenous vein. Moreover, VEGF/ VPF expression was identified in 32 (97%) of 33 pathological coronary arterial specimens; the extent of VEGF/VPF staining was graded as moderate to strong in 21 of the 32 (66%) positive specimens. VEGF/VPF double immunostaining and in situ hybridization demonstrated that smooth muscle cells constitute the principal cellular source of VEGF/VPF. VEGF/VPF immunostaining among primary atherosclerotic lesions localized predominantly to the extracellular matrix. In restenotic specimens, VEGF/VPF immunostaining was more prominently cellular, particularly among proliferating smooth muscle cells. Although VEGF/VPF expression was observed in areas of macrophage infiltration, double immunostaining failed to localize VEGF/VPF to macrophages in these foci; instead, double immunostaining clearly identified CD45RO-positive cells as responsible for VEGF/VPF expression in such areas. No correlation could be demonstrated between VEGF/VPF immunostaining and extent of vasa vasorum. These findings thus establish that postnatal VEGF/VPF expression is a feature of normal human arteries and veins and is often extensively expressed in arteries narrowed by atherosclerotic plaque. VEGF/VPF expression in the wall and/or plaque of medium to large vessels suggests a role for VEGF/VPF other than promoting angiogenesis. This role may involve maintenance and repair of luminal endothelium. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:9137092

  7. PIV Measurements of Turbulent Flow Over a Permeable Wall using a Refractive-Index Matching Approach

    NASA Astrophysics Data System (ADS)

    Kim, T.; Blois, G.; Best, J. L.; Christensen, K. T.

    2013-11-01

    Turbulent flows over permeable walls occur in a variety of natural environments and engineering applications. Unlike classical and widely-studied flows over impermeable walls, the peculiar dynamics of flow generated by permeable walls are poorly understood. Early studies suggest that the well-known higher energy dissipation induced by permeability (as compared to impermeable walls with similar roughness) can be explained by unveiling the flow interactions within the transition layer that forms at the interface between the overlying flow and the permeable wall. To overcome the challenges associated with quantifying the flow character both above and within a permeable wall, a Refractive-Index-Matching (RIM) approach was employed. Doing so facilitated optical access to the fluid flowing through the permeable wall, thus yielding direct PIV pore-space flow measurements within the transition layer. The permeable wall was formed by packing acrylic spheres in a cubic arrangement and was then immersed in an aqueous solution of sodium iodide at a concentration and temperature that ensured accurate refractive index match with the wall. Measurements were focused on the flow across the wall interface and the turbulent attributes of these surface-subsurface interactions were detailed.

  8. A dynamic shift of VEGF isoforms with a transient and selective progesterone-induced expression of VEGF189 regulates angiogenesis and vascular permeability in human uterus

    Microsoft Academic Search

    Magali Ancelin; Hélène Buteau-Lozano; Geri Meduri; Mary Osborne-Pellegrin; Sylvie Sordello; Jean Plouët; Martine Perrot-Applanat

    2002-01-01

    A key mechanism underlying physiological angiogenesis of the human endometrium is its ability to regenerate the vascular capillary network and to perform vascular remodeling (i.e., development of spiral arteries). Vascular endothelial growth factor (VEGF) is associated with angiogenesis and capillary permeability in this tissue. VEGF is expressed as several spliced variants, its main human isoforms contain 121 and 165 aa;

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

    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

    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

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

    SciTech Connect

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

    1989-03-01

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

  12. Vagus nerve stimulation blocks vascular permeability following burn injury in both local and distal sites

    PubMed Central

    Ortiz-Pomales, Yan T; Krzyzaniak, Michael; Coimbra, Raul; Baird, Andrew; Eliceiri, Brian P.

    2012-01-01

    Recent studies have shown that vagus nerve stimulation (VNS) can block the burn injury-induced systemic inflammatory response (SIRS). In this study we examined the potential for VNS to modulate vascular permeability (VP) in local sites (i.e. skin) and in secondary sites (i.e. lung) following burn injury. In a 30% total body surface area burn injury model, VP was measured using intravascular fluorescent dextran for quantification of the VP response in skin and lung. A peak in VP of the skin was observed 24 hours post-burn injury, that was blocked by VNS. Moreover, in the lung, VNS led to a reduction in burn-induced VP compared to sham-treated animals subjected to burn injury alone. The protective effects of VNS in this model were independent of the spleen, suggesting that the spleen was not a direct mediator of VNS. These studies identify a role for VNS in the regulation of VP in burns, with the translational potential of attenuating lung complications following burn injury. PMID:22694873

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

    SciTech Connect

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

    1986-12-01

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

  14. Vascular remodeling alters adhesion protein and cytoskeleton reactions to inflammatory stimuli resulting in enhanced permeability increases in rat venules

    PubMed Central

    Yuan, Dong

    2012-01-01

    Vascular remodeling has been implicated in many inflammation-involved diseases. This study aims to investigate the microvascular remodeling-associated alterations in cell-cell adhesion and cytoskeleton reactions to inflammatory stimuli and their impact on microvessel permeability. Experiments were conducted in individually perfused rat mesenteric venules. Microvessel permeability was determined by measuring hydraulic conductivity (Lp), and endothelial intracellular calcium concentration, [Ca2+]i, was measured in fura-2-perfused vessels. Alterations in VE-cadherin and F-actin arrangement were examined by confocal imaging. Vascular wall cellular composition and structural changes were evaluated by electron microscopy. Vessels exposed to platelet activating factor (PAF) on day 1 were reevaluated 3 days later in rats that had undergone survival surgery. Initial PAF exposure and surgical disturbance increased microvascular wall thickness along with perivascular cell proliferation and altered F-actin arrangement. Although basal permeability was not changed, upon reexposure to PAF, peak endothelial [Ca2+]i was augmented and the peak Lp was 9.3 ± 1.7 times higher than that of day 1. In contrast to patterns of PAF-induced stress fiber formation and VE-cadherin redistribution observed in day 1 vessels, the day 4 vessels at the potentiated Lp peak exhibited wide separations of VE-cadherin between endothelial cells and striking stress fibers throughout the vascular walls. Confocal images and ultrastructural micrographs also revealed that the largely separated VE-cadherin and endothelial gaps were completely covered by F-actin bundles in extended pericyte processes at the PAF-induced Lp peak. These results indicate that inflammation-induced vascular remodeling increased endothelial susceptibility to inflammatory stimuli with augmented Ca2+ response resulting in upregulated contractility and potentiated permeability increase. Weakened adhesions between the endothelial cells and contractile mechanisms are both involved in increasing permeability in the intact microvessels and are aggravated during remodeling. The perivascular cells play important roles in stabilizing the microvessel wall, while lessening an otherwise much greater magnitude of leakage during cytoskeletal contraction. PMID:22837164

  15. Role of Staphylococcus aureus Virulence Factors in Inducing Inflammation and Vascular Permeability in a Mouse Model of Bacterial Endophthalmitis

    PubMed Central

    Kumar, Ajay; Kumar, Ashok

    2015-01-01

    Staphylococcus (S.) aureus is a common causative agent of bacterial endophthalmitis, a vision threatening complication of eye surgeries. The relative contribution of S. aureus virulence factors in the pathogenesis of endophthalmitis remains unclear. Here, we comprehensively analyzed the development of intraocular inflammation, vascular permeability, and the loss of retinal function in C57BL/6 mouse eyes, challenged with live S. aureus, heat-killed S. aureus (HKSA), peptidoglycan (PGN), lipoteichoic acid (LTA), staphylococcal protein A (SPA), ?-toxin, and Toxic-shock syndrome toxin 1 (TSST1). Our data showed a dose-dependent (range 0.01 ?g/eye to 1.0 ?g/eye) increase in the levels of inflammatory mediators by all virulence factors. The cell wall components, particularly PGN and LTA, seem to induce higher levels of TNF-?, IL-6, KC, and MIP2, whereas the toxins induced IL-1?. Similarly, among the virulence factors, PGN induced higher PMN infiltration. The vascular permeability assay revealed significant leakage in eyes challenged with live SA (12-fold) and HKSA (7.3-fold), in comparison to other virulence factors (~2-fold) and controls. These changes coincided with retinal tissue damage, as evidenced by histological analysis. The electroretinogram (ERG) analysis revealed a significant decline in retinal function in eyes inoculated with live SA, followed by HKSA, SPA, and ?-toxin. Together, these findings demonstrate the differential innate responses of the retina to S. aureus virulence factors, which contribute to intraocular inflammation and retinal function loss in endophthalmitis. PMID:26053426

  16. Generalized nonlinear Schrödinger equation for dispersive susceptibility and permeability: application to negative index materials.

    PubMed

    Scalora, Michael; Syrchin, Maxim S; Akozbek, Neset; Poliakov, Evgeni Y; D'Aguanno, Giuseppe; Mattiucci, Nadia; Bloemer, Mark J; Zheltikov, Aleksei M

    2005-07-01

    A new generalized nonlinear Schrödinger equation describing the propagation of ultrashort pulses in bulk media exhibiting frequency dependent dielectric susceptibility and magnetic permeability is derived and used to characterize wave propagation in a negative index material. The equation has new features that are distinct from ordinary materials (mu=1): the linear and nonlinear coefficients can be tailored through the linear properties of the medium to attain any combination of signs unachievable in ordinary matter, with significant potential to realize a wide class of solitary waves. PMID:16090616

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

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2013-10-01

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

  19. Pressure–cornea–vascular index (PCVI) for predicting disease progression in normal tension glaucoma

    Microsoft Academic Search

    Dexter Y L Leung; Milko E Iliev; Poemen Chan; Nafees Baig; Stanley C C Chi; Clement C Y Tham; Dennis S C Lam

    2010-01-01

    BackgroundIt has been shown that the pressure-to-cornea index (PCI), which estimates the relative effects of intraocular pressure (IOP) and central corneal thickness (CCT), may differentiate between glaucoma and non-glaucoma states. The authors investigated the utility of the pressure–cornea–vascular index (PCVI) in predicting field-progression in patients with normal tension glaucoma (NTG).MethodsPCVI was constructed from PCI (maximum IOP\\/CCT3) extended with risk factors

  20. Characterization of Vascular Disruption and Blood–Spinal Cord Barrier Permeability following Traumatic Spinal Cord Injury

    PubMed Central

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

    2014-01-01

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

  1. Vascular Permeability and Transvascular Fluid and Protein Transport in the Dog Lung

    Microsoft Academic Search

    JAMES C. PARKER; RICHARD E. PARKER; D. NEIL GRANGER; AUBREY E. TAYLOR

    SUMMARY We used steady state lymph-to-plasma concentration ratios of six endogenous protein fractions (effective hydrodynamic radii of 37,40,44, 53,100, and 120 A) to estimate pulmonary capillary permeability characteristics. Pulmonary lymph was collected from an afferent lymphatic to the left tracheobronchial lymph node, and left atrial pressure was elevated in steps until the lymphatic protein concentration obtained a constant value. Lymph

  2. Hydrogen-Rich Medium Attenuated Lipopolysaccharide-Induced Monocyte-Endothelial Cell Adhesion and Vascular Endothelial Permeability via Rho-Associated Coiled-Coil Protein Kinase.

    PubMed

    Xie, Keliang; Wang, Weina; Chen, Hongguang; Han, Huanzhi; Liu, Daquan; Wang, Guolin; Yu, Yonghao

    2015-07-01

    Sepsis is the leading cause of death in critically ill patients. In recent years, molecular hydrogen, as an effective free radical scavenger, has been shown a selective antioxidant and anti-inflammatory effect, and it is beneficial in the treatment of sepsis. Rho-associated coiled-coil protein kinase (ROCK) participates in junction between normal cells, and regulates vascular endothelial permeability. In this study, we used lipopolysaccharide to stimulate vascular endothelial cells and explored the effects of hydrogen-rich medium on the regulation of adhesion of monocytes to endothelial cells and vascular endothelial permeability. We found that hydrogen-rich medium could inhibit adhesion of monocytes to endothelial cells and decrease levels of adhesion molecules, whereas the levels of transepithelial/endothelial electrical resistance values and the expression of vascular endothelial cadherin were increased after hydrogen-rich medium treatment. Moreover, hydrogen-rich medium could lessen the expression of ROCK, as a similar effect of its inhibitor Y-27632. In addition, hydrogen-rich medium could also inhibit adhesion of polymorphonuclear neutrophils to endothelial cells. In conclusion, hydrogen-rich medium could regulate adhesion of monocytes/polymorphonuclear neutrophils to endothelial cells and vascular endothelial permeability, and this effect might be related to the decreased expression of ROCK protein. PMID:25895142

  3. Selective Requirement for Src Kinases during VEGF-Induced Angiogenesis and Vascular Permeability

    Microsoft Academic Search

    Brian P Eliceiri; Robert Paul; Pamela L Schwartzberg; John D Hood; Jie Leng; David A Cheresh

    1999-01-01

    Src kinase activity was found to protect endothelial cells from apoptosis during vascular endothelial growth factor (VEGF)–, but not basic fibroblast growth factor (bFGF)–, mediated angiogenesis in chick embryos and mice. In fact, retroviral targeting of kinase-deleted Src to tumor-associated blood vessels suppressed angiogenesis and the growth of a VEGF-producing tumor. Although mice lacking individual Src family kinases (SFKs) showed

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

    PubMed

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

    2014-01-01

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

  5. Tc-99m radioaerosol clearance as an index of pulmonary epithelial permeability

    SciTech Connect

    Waldman, D.L.

    1988-01-01

    This investigation examines radiopharmaceutical clearance as an index of alveolar-capillary membrane permeability and as an indicator of disease. Specific objectives include: evaluation of radiopharmaceutical chemical purity following aerosolization, investigation of a chemically related family of compounds to develop new radiopharmaceuticals with improved chemical properties, determination of reproducibility of the radiopharmaceutical clearance technique and the evaluation of the sensitivity of aerosolized solute clearance as an indicator of lung injury. The integrity of the radiopharmaceutical was examined prior to and following aerosol generation. The in vivo pharmacokinetics of a family of aerosolized solutes was evaluated in the beagle dog. The reproducibility of the biological response to radiopharmaceutical deposition was evaluated using dynamic functional imaging in humans and in the beagle. The sensitivity of the technique was evaluated using Tc-99m DTPA and an animal model for lung injury.

  6. Cutaneous inflammation: effects of hydroxy acids and eicosanoid pathway inhibitors on vascular permeability.

    PubMed

    Waldman, J S; Marcus, A J; Soter, N A; Lim, H W

    1989-01-01

    Four metabolic products of arachidonic acid lipoxygenation, 5-hydroxyeicosatetraenoate (5-HETE), 12-HETE, 15-HETE, 5(S),12(S)-DiHETE, were injected intradermally into depilated dorsae of albino guinea pigs. The presence of intravenously injected 125I-bovine serum albumin (10uCi/kg) in 13-mm punch biopsy specimens served as a marker for altered vascular response; histologic changes were evaluated at 6 and 24 h after the injection in 1-micron-thick sections. Thirty minutes after the injections of 15 nanomoles and 60 nanomoles of 5-HETE, the ratios of radioactivity in HETE-injected to that in buffer-injected sites were 1.35 +/- 0.06 (mean +/- SE) and 2.80 +/- 0.27, respectively. Corresponding effects of 15-HETE were 1.39 +/- 0.17 and 1.63 +/- 0.21, respectively. Values for 60 nanomoles of 12-HETE and 5,12-DiHETE were intermediate in comparison with the above eicosanoids. The most notable histologic changes were a neutrophilic infiltrate induced by 12-HETE at 6 and 24 h, and neutrophilic and eosinophilic infiltrates in response to 5,12-DiHETE injection at 6 and 24 h. Effects of topically applied eicosanoid pathway inhibitors were also evaluated, using intradermally injected sodium arachidonate (AA) as agonist. Three mixed cyclooxygenase/lipoxygenase inhibitors, BW755C, phenidone, and nordihydroguaiaretic acid, suppressed vascular response by 9%, 9%, and 6% for 150 nmol of AA, and by 9%, 13%, and 12% for 300 nmol of AA, respectively. The cyclooxygenase inhibitor, indomethacin, induced suppressions of 39% for 150 nmol AA and 22% for 300 nmol AA, respectively. These data demonstrate that metabolites of both cyclooxygenase and lipoxygenase eicosanoid pathways are involved in alteration in vascular response accompanying cutaneous inflammation. PMID:2491876

  7. Host endothelial S1PR1 regulation of vascular permeability modulates tumor growth

    PubMed Central

    Sarkisyan, Gor; Gay, Laurie J.; Nguyen, Nhan; Felding, Brunhilde H.

    2014-01-01

    Understanding vascular growth and maturation in developing tumors has important implications for tumor progression, spread, and ultimately host survival. Modulating the signaling of endothelial G protein-coupled receptors (GPCRs) in blood and lymphatic vessels can enhance or limit tumor progression. Sphingosine 1-phosphate receptor 1 (S1PR1) is a GPCR for circulating lysophospholipid S1P that is highly expressed in blood and lymphatic vessels. Using the S1PR1- enhanced green fluorescent protein (eGFP) mouse model in combination with intravital imaging and pharmacologic modulation of S1PR1 signaling, we show that boundary conditions of high and low S1PR1 signaling retard tumor progression by enhancing or destabilizing neovasculature integrity, respectively. In contrast, midrange S1PR1 signaling, achieved by receptor antagonist titration, promotes abundant growth of small, organized vessels and thereby enhances tumor progression. Furthermore, in vivo S1PR1 antagonism supports lung colonization by circulating tumor cells. Regulation of endothelial S1PR1 dynamically controls vascular integrity and maturation and thus modulates angiogenesis, tumor growth, and hematogenous metastasis. PMID:24740542

  8. Analysis of the tumor vasculature and metastatic behavior of xenografts of human melanoma cell lines transfected with vascular permeability factor.

    PubMed Central

    Pötgens, A. J.; van Altena, M. C.; Lubsen, N. H.; Ruiter, D. J.; de Waal, R. M.

    1996-01-01

    Vascular permeability factor (VPF) is an important mediator of vascular development in tumors. Some human melanoma cell lines have a low VPF expression level in culture, but this level is upregulated when growing as a tumor in nude mice. Other melanoma lines have a constitutively high VPF expression. To compare the biological behavior of tumors with these two expression patterns, a human melanoma cell line with an inducible VPF expression was transfected with VPF expression constructs. In this way, several lines were obtained that constitutively produce either the soluble VPF121 or the matrix-associated VPF189 variant at levels of 4 to 30 times the VPF level in mature tumors derived from the parental line. The recombinant VPF RNA, which lacks most of the 5' noncoding sequences present in the endogenous VPF mRNA, was much more efficiently translated than the endogenous messenger. Upon injection in nude mice, all VPF-transfected lines developed tumors with aberrations in vascularization and in distribution of matrix components. In these tumors the blood vessels were hyperpermeable for an i.v. injected protein tracer. Transfection did not influence the in vitro growth rate of the cell lines, but the tumors from the VPF-transfected lines had higher growth rates in vivo than tumors from the parental line or the vector-transfected line. Although the incidence of lung metastasis was similar in all lines, the number of metastases per affected lung was significantly increased in mice carrying VPF-transfectant tumors. We conclude that the pattern and the level of VPF expression in a tumor are important determinants of the architecture and functionality of the vascular bed, but that overexpression of VPF does not necessarily lead to an increase of microvascular density or metastatic spread. The role of VPF in melanoma progression is obviously complex and may be difficult to derive in its generality from a single experimental model. Images Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 PMID:8644861

  9. Systems-level analysis of proteolytic events in increased vascular permeability and complement activation in skin inflammation.

    PubMed

    auf dem Keller, Ulrich; Prudova, Anna; Eckhard, Ulrich; Fingleton, Barbara; Overall, Christopher M

    2013-01-15

    During inflammation, vascular permeability is increased by various proteolytic events, such as the generation of bradykinin, that augment local tissue responses by enabling tissue penetration of serum proteins, including complement and acute-phase proteins. Proteases also govern inflammatory responses by processing extracellular matrix proteins and soluble bioactive mediators. We quantified changes in the proteome and the nature of protein amino termini (the N-terminome) and the altered abundance of murine proteases and inhibitors during skin inflammation. Through analysis of the N-terminome by iTRAQ-TAILS, we identified cotranslational and posttranslational ?N-acetylation motifs, quantitative increases in protein abundance, and qualitative changes in the proteolytic signature during inflammation. Of the proteins identified in normal skin, about half were cleaved, and phorbol ester-induced inflammation increased the proportion of cleaved proteins, including chemokines and complement proteins, that were processed at previously uncharacterized sites. In response to phorbol ester-induced inflammation, mice deficient in matrix metalloproteinase 2 (MMP2) showed reduced accumulation of serum proteins in the skin and exhibited different proteolytic networks from those of wild-type mice. We found that the complement 1 (C1) inhibitor attenuated the increase in serum protein accumulation in inflamed skin. Cleavage and inactivation of the C1 inhibitor by MMP2 increased complement activation and bradykinin generation in wild-type mice, leading to increased vessel permeability during inflammation, which was diminished in Mmp2(-/-) mice. Thus, our systems-level analysis of proteolysis dissected cleavage events associated with skin inflammation and demonstrated that loss of a single protease could perturb the proteolytic signaling network and enhance inflammation. PMID:23322905

  10. Interactions between histamine and bradykinin assessed by continuous recording of increased vascular permeability

    PubMed Central

    Baumgarten, A.; Melrose, G. J. H.; Vagg, W. J.

    1970-01-01

    1. The responses of the cutaneous blood vessels of the guinea-pig to histamine and bradykinin have been studied in order to determine whether these factors mediate vascular changes by acting on different blood vessel receptors. 2. In animals injected intravenously with bovine serum albumin labelled with phosphorus 32P the reactions to histamine and bradykinin have been studied by continuously recording the local radioactive emission from the skin. 3. Histamine increased the intensity of radioactive emission for 7-15 min. The level of radioactivity then remained almost constant for at least 1 hr. Bradykinin increased the rate of emission for 5-7 min but the radioactivity decreased by approx. 30% in 1 hr. 4. The intensity of the response to histamine was markedly diminished in sites previously treated with either histamine or bradykinin, compared with the reaction in normal skin. However, a response of similar intensity to that in normal skin was evoked by histamine earlier in sites previously treated with bradykinin than in sites treated with histamine. By contrast, bradykinin evoked a similar reaction to that in normal skin, in sites previously treated with either histamine or bradykinin. 5. The dissimilarity of the responses evoked by histamine and bradykinin suggests that there are two types of blood vessel receptors. One type may be activated by both histamine and bradykinin but becomes refractory to further stimulation with histamine. The other type of receptor is activated only by bradykinin and does not become refractory. PMID:5499789

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

    PubMed Central

    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

    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

  12. Mitogen-Activated Protein Kinase–Activated Protein Kinase 2 Mediates Apoptosis during Lung Vascular Permeability by Regulating Movement of Cleaved Caspase 3

    PubMed Central

    Parniani, Ahmad R.; Johnston, Laura; Maredia, Hasina; Serebreni, Leonid; Hamdan, Omar; Sidhaye, Venkataramana K.; Shimoda, Larissa A.; Myers, Allen C.; Crow, Michael T.; Schmidt, Eric P.; Machamer, Carolyn E.; Gaestel, Matthias; Rane, Madhavi J.; Kolb, Todd M.; Kim, Bo S.; Damico, Rachel L.; Hassoun, Paul M.

    2014-01-01

    Apoptosis is a key pathologic feature in acute lung injury. Animal studies have demonstrated that pathways regulating apoptosis are necessary in the development of acute lung injury, and that activation of p38 mitogen-activated protein kinase (MAPK) is linked to the initiation of the apoptotic cascade. In this study, we assessed the role of the MAPK-activated protein kinase (MK) 2, one of p38 MAPK’s immediate downstream effectors, in the development of apoptosis in an animal model of LPS-induced pulmonary vascular permeability. Our results indicate that wild-type (WT) mice exposed to LPS demonstrate increased apoptosis, as evidenced by cleavage of caspase 3 and poly (ADP-ribose) polymerase 1 and increased deoxynucleotidyl transferase–mediated dUDP nick-end labeling staining, which is accompanied by increases in markers of vascular permeability. In contrast, MK2?/? mice are protected from pulmonary vascular permeability and apoptosis in response to LPS. Although there was no difference in activation of caspase 3 in MK2?/? compared with WT mice, interestingly, cleaved caspase 3 translocated to the nucleus in WT mice while it remained in the cytosol of MK2?/? mice in response to LPS. In separate experiments, LPS-induced apoptosis in human lung microvascular endothelial cells was also associated with nuclear translocation of cleaved caspase 3 and apoptosis, which were both prevented by MK2 silencing. In conclusion, our data suggest that MK2 plays a critical role in the development of apoptosis and pulmonary vascular permeability, and its effects on apoptosis are in part related to its ability to regulate nuclear translocation of cleaved caspase 3. PMID:24304496

  13. Increased vascular permeability and polymorphonuclear leucocyte accumulation in vivo in response to recombinant cytokines and supernatant from cultures of human synovial cells treated with interleukin 1.

    PubMed Central

    Watson, M. L.; Lewis, G. P.; Westwick, J.

    1989-01-01

    The inflammatory effects of intradermal injections of the human recombinant cytokines interleukin 1 (IL-1), granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumour necrosis factor (TNF alpha) have been assessed in rabbit skin, and compared with the effects of a novel polymorphonuclear leucocyte (PMN)-stimulating activity (PSA) produced by IL-1-treated human synovial cell cultures. IL-1 (84 fmol) and GM-CSF (10 pmol) caused increases in vascular permeability with a delayed onset, as assessed by the dermal accumulation of intravenously-administered 125I-human serum albumin. These cytokines also stimulated extravascular accumulation of PMNs. In contrast, PSA-containing supernatant caused a more rapid and prolonged increase in vascular permeability and PMN accumulation. TNF alpha (84 fmol) was unable to stimulate either of these responses. The increases in vascular permeability and PMN accumulation following IL-1 administration in vivo may be a consequence of the local generation of PMN-stimulating activity by connective tissue cells, such as the activity produced by IL-1-treated synovial cell cultures that we have described. PMID:2647120

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

    PubMed Central

    MAEDA, Hiroshi

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  16. Application of the Red List Index for conservation assessment of Spanish vascular plants.

    PubMed

    Saiz, Juan Carlos Moreno; Lozano, Felipe Domínguez; Gómez, Manuel Marrero; Baudet, Ángel Bañares

    2015-06-01

    The International Union for Conservation of Nature (IUCN) Red List Index (RLI) is used to measure trends in extinction risk of species over time. The development of 2 red lists for Spanish vascular flora during the past decade allowed us to apply the IUCN RLI to vascular plants in an area belonging to a global biodiversity hotspot. We used the Spanish Red Lists from 2000 and 2010 to assess changes in level of threat at a national scale and at the subnational scales of Canary Islands, Balearic Islands, and peninsular Spain. We assigned retrospective IUCN categories of threat to 98 species included in the Spanish Red List of 2010 but absent in the Spanish Red List of 2000. In addition, we tested the effect of different random and taxonomic and spatial Spanish samples on the overall RLI value. From 2000 to 2010, the IUCN categories of 768 species changed (10% of Spanish flora), mainly due to improved knowledge (63%), modifications in IUCN criteria (14%), and changes in threat status (12%). All measured national and subnational RLI values decreased during this period, indicating a general decline in the conservation status of the Spanish vascular flora. The Canarian RLI value (0.84) was the lowest, although the fastest deterioration in conservation status occurred on peninsular Spain (from 0.93 in 2000 to 0.92 in 2010). The RLI values based on subsamples of the Spanish Red List were not representative of RLI values for the entire country, which would discourage the use of small areas or small taxonomic samples to assess general trends in the endangerment of national biotas. The role of the RLI in monitoring of changes in biodiversity at the global and regional scales needs further reassessment because additional areas and taxa are necessary to determine whether the index is sufficiently sensitive for use in assessing temporal changes in species' risk of extinction. PMID:25580521

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

    PubMed

    Morita, Shoko; Hourai, Atsushi; Miyata, Seiji

    2014-01-01

    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

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

    PubMed

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

    2014-10-01

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

  19. Mechanisms Associated with Tumor Vascular Shut-Down Induced by Combretastatin A-4 Phosphate: Intravital Microscopy and Measurement of Vascular Permeability1

    Microsoft Academic Search

    Gillian M. Tozer; Vivien E. Prise; John Wilson; Maja Cemazar; Siqing Shan; Mark W. Dewhirst; Paul R. Barber; Borivoj Vojnovic; David J. Chaplin

    2001-01-01

    The tumor vascular effects of the tubulin destabilizing agent disodium combretastatin A-4 3-O-phosphate (CA-4-P) were investigated in the rat P22 tumor growing in a dorsal skin flap window chamber implanted into BD9 rats. CA-4-P is in clinical trial as a tumor vascular targeting agent. In animal tumors, it can cause the shut-down of blood flow, leading to extensive tumor cell

  20. Common variants of chemokine receptor gene CXCR3 and its ligands CXCL10 and CXCL11 associated with vascular permeability of dengue infection in peninsular Malaysia.

    PubMed

    Hoh, B P; Umi-Shakina, H; Zuraihan, Z; Zaiharina, M Z; Rafidah-Hanim, S; Mahiran, M; Nik Khairudin, N Y; Benedict, L H Sim; Masliza, Z; Christopher, K C Lee; Sazaly, A B

    2015-06-01

    Dengue causes significantly more human disease than any other arboviruses. It causes a spectrum of illness, ranging from mild self-limited fever, to severe and fatal dengue hemorrhagic fever, as evidenced by vascular leakage and multifactorial hemostatic abnormalities. There is no specific treatment available till date. Evidence shows that chemokines CXCL10, CXCL11 and their receptor CXCR3 are involved in severity of dengue, but their genetic association with the susceptibility of vascular leakage during dengue infection has not been reported. We genotyped 14 common variants of these candidate genes in 176 patients infected with dengue. rs4859584 and rs8878 (CXCL10) were significantly associated with vascular permeability of dengue infection (P<0.05); while variants of CXCL11 showed moderate significance of association (P=0.0527). Haplotype blocks were constructed for genes CXCL10 and CXCL11 (5 and 7 common variants respectively). Haplotype association tests performed revealed that, "CCCCA" of gene CXCL10 and "AGTTTAC" of CXCL11 were found to be significantly associated with vascular leakage (P=0.0154 and 0.0366 respectively). In summary, our association study further strengthens the evidence of the involvement of CXCL10 and CXCL11 in the pathogenesis of dengue infection. PMID:25858769

  1. Myc regulates embryonic vascular permeability and remodeling Enik Kokai (1), Florian Voss (2), Frank Fleischer (2), Sybille Kempe (1), Dragan

    E-print Network

    Schmidt, Volker

    by sprouting and intussusception 1 . The immature vascular tree adjusts to changes in blood flow and oxygen on embryonic blood vessel formation CIRCRESAHA/2008/191460/R2 #12;1 Abstract Previous work has shown that c in vascular basement membrane composition or pericyte coverage. However, the overall turnover of endothelial

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

    PubMed

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

    2015-02-28

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

  3. Clothing ventilation, vapour resistance and permeability index: changes due to posture, movement and wind

    Microsoft Academic Search

    GEORGE HAVENITH; RONALD HEUS; WOUTER A. LOTENS

    1990-01-01

    Using the trace gas diffusion method, the vapour resistance of three clothing ensembles (two permeable and one impermeable) was determined for four subjects, sitting, standing or walking at 0-3 and 09 m\\/s, combined with three wind speeds of <0-15, 0-7 and 41 m\\/s. Sitting increased vapour resistance by 12-36%, whereas walking and wind decreased the resistance by 72% and 89%

  4. Pre-B cell colony enhancing factor (PBEF/NAMPT/Visfatin) and vascular endothelial growth factor (VEGF) cooperate to increase the permeability of the human placental amnion.

    PubMed

    Astern, J M; Collier, A C; Kendal-Wright, C E

    2013-01-01

    Fluid efflux across the region of the amnion overlying the placenta is an essential component of the intramembranous absorption pathway that maintains amniotic fluid volume homeostasis. Dysregulation of this pathway may result in adverse pregnancy outcomes, however the factors controlling amnion permeability are unknown. Here, we report a novel mechanism that increases placental amnion permeability. Pre-B Cell Colony Enhancing Factor (PBEF) is a stress-responsive cytokine expressed by the human amnion, and is known to induce Vascular Endothelial Growth Factor (VEGF) production by other cell types. Interestingly, VEGF is up-regulated in the ovine amnion when intramembranous absorption is augmented. In this study, we show that PBEF induced VEGF secretion by primary human amniotic epithelial cells (AEC) derived from the placental amnion, as well as from the reflected amnion that lines the remainder of the gestational sac. Further, PBEF treatment led to the increased expression of VEGFR2 in placental AEC, but not reflected AEC. To test the hypothesis that PBEF and VEGF increase placental amnion permeability, we monitored the transfer of 2',7'-dichlorofluorescein (DCF) from the fetal to the maternal side of human amnion explants. A treatment regimen including both PBEF and VEGF increased the rate of DCF transfer across the placental amnion, but not the reflected amnion. In summary, our results suggest that by augmenting VEGFR2 expression in the placental amnion, PBEF primes the tissue for a VEGF-mediated increase in permeability. This mechanism may have important implications in amniotic fluid volume control throughout gestation. PMID:23151382

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

    SciTech Connect

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

    2010-09-15

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

  6. Increase in milk metalloproteinase activity and vascular permeability in bovine endotoxin-induced and naturally occurring Escherichia coli mastitis

    Microsoft Academic Search

    S. M. Raulo; T. Sorsa; T. Tervahartiala; T. Latvanen; E. Pirilä; J. Hirvonen; P. Maisi

    2002-01-01

    An endotoxin-induced mastitis model was used to study permeability changes associated with increased milk matrix metalloproteinase (MMP) activity in early inflammation. One quarter of two cows was inoculated with endotoxin (Escherichia coli 055:B5). Blood, milk, and whey were collected before and repeatedly after inoculation for 48h. The profile and amounts of gelatinolytic MMPs were determined by zymography; gelatinase A (72kD

  7. Protective Effects of N-Acetyl Cysteine against Diesel Exhaust Particles-Induced Intracellular ROS Generates Pro-Inflammatory Cytokines to Mediate the Vascular Permeability of Capillary-Like Endothelial Tubes

    PubMed Central

    Tseng, Chia-Yi; Chang, Jing-Fen; Wang, Jhih-Syuan; Chang, Yu-Jung; Gordon, Marion K.; Chao, Ming-Wei

    2015-01-01

    Exposure to diesel exhaust particles (DEP) is associated with pulmonary and cardiovascular diseases. Previous studies using in vitro endothelial tubes as a simplified model of capillaries have found that DEP-induced ROS increase vascular permeability with rearrangement or internalization of adherens junctional VE-cadherin away from the plasma membrane. This allows DEPs to penetrate into the cell and capillary lumen. In addition, pro-inflammatory cytokines are up-regulated and mediate vascular permeability in response to DEP. However, the mechanisms through which these DEP-induced pro-inflammatory cytokines increase vascular permeability remain unknown. Hence, we examined the ability of DEP to induce permeability of human umbilical vein endothelial cell tube cells to investigate these mechanisms. Furthermore, supplementation with NAC reduces ROS production following exposure to DEP. HUVEC tube cells contributed to a pro-inflammatory response to DEP-induced intracellular ROS generation. Endothelial oxidative stress induced the release of TNF-? and IL-6 from tube cells, subsequently stimulating the secretion of VEGF-A independent of HO-1. Our data suggests that DEP-induced intracellular ROS and release of the pro-inflammatory cytokines TNF- ? and IL-6, which would contribute to VEGF-A secretion and disrupt cell-cell borders and increase vasculature permeability. Addition of NAC suppresses DEP-induced ROS efficiently and reduces subsequent damages by increasing endogenous glutathione. PMID:26148005

  8. Palomid 529, a novel small-molecule drug, is a TORC1/TORC2 inhibitor that reduces tumor growth, tumor angiogenesis, and vascular permeability.

    PubMed

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

    2008-11-15

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

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed

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

    2014-10-01

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

  11. Blood-ocular barrier breakdown in eyes with ocular melanoma. A potential role for vascular endothelial growth factor/vascular permeability factor.

    PubMed Central

    Vinores, S. A.; Küchle, M.; Mahlow, J.; Chiu, C.; Green, W. R.; Campochiaro, P. A.

    1995-01-01

    A series of 130 eyes with ocular melanomas, 19 normal eyes, and 18 eyes affected with other disorders leading to blood-ocular barrier (BOB) breakdown were immunohistochemically stained for albumin to localize sites of BOB failure within the retina, ciliary body, and iris. Thirty-nine of the eyes containing melanomas and all of the other eyes were also immunohistochemically stained for vascular endothelial growth factor (VEGF), to investigate its potential role as a mediator for BOB failure. Eyes with melanomas showed widespread leakage through the retinal pigment epithelium, and 58% demonstrated leakage from retinal vessels in the proximity of the tumor. BOB failure remote from the tumor also occurred in retina (50%), optic nerve head (77%), ciliary body (51%), and iris (51%), suggesting that a soluble mediator may be involved. VEGF was demonstrated intraretinally in the proximity of (46%) and remote from (24%) melanomas and in eyes affected by other disease processes, particularly those involving neoplasia or retinal detachments, usually within particular cell populations (ie, retinal vessel walls, ganglion cells, inner or outer nuclear layers, retinal pigment epithelium). VEGF localization in retina, ciliary body, and iris often coincided with sites of extravasated albumin. Preincubation of albumin or VEGF antibodies with normal serum or VEGF peptide, respectively, eliminated or markedly reduced all immunoreactivity. Only 1 of 14 normal postmortem eyes and 0 of 5 normal surgically removed eyes showed VEGF positivity in the retina, 5 of 19 normal eyes had weak positivity in the ciliary body, and VEGF was not demonstrated in the iris of normal eyes. VEGF cannot account for all of the BOB failure associated with ocular melanomas, but appears likely to play a contributing role in many cases. Images Figure 1 Figure 2 Figure 3 PMID:7485392

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

    PubMed Central

    2014-01-01

    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

  13. Association of cardio-ankle vascular index with physical fitness and cognitive symptoms in aging Finnish firefighters

    Microsoft Academic Search

    H. Lindholm; A. Punakallio; S. Lusa; M. Sainio; E. Ponocny; R. Winker

    Purpose  Monitoring cardiovascular risk factors is important in health promotion among firefighters. The assessment of arterial stiffness\\u000a (AS) may help to detect early signs of atherosclerosis. The aim of this study was to analyze associations between aerobic\\u000a fitness, cognitive symptoms and cardio-ankle vascular index (CAVI) as a measure for AS among Finnish firefighters.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  The data are one part of a large

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

    PubMed Central

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

    2013-01-01

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

  15. Overexpression of Thrombospondin1 Reduces Growth and Vascular Index but not Perfusion in Glioblastoma1

    Microsoft Academic Search

    Michael Kragh; Bjørn Quistorff; Mirna Tenan; Erwin G. Van Meir; Paul E. G. Kristjansen

    2002-01-01

    Little is known about the effects of antiangiogenic therapy on perfusion of human tumors and the mechanisms by which tumors can adapt to these treatments and recur. Here, we examined the effects of serial passaging of LN-229 human glioma xenografts overexpressing thrombospondin (TSP)-1 on tumor growth, vascularity, and perfusion. Persistence of TSP-1 overexpression was confirmed after three serial s.c. passages

  16. Pathogenesis of periodontitis: a major arginine-specific cysteine proteinase from Porphyromonas gingivalis induces vascular permeability enhancement through activation of the kallikrein/kinin pathway.

    PubMed Central

    Imamura, T; Pike, R N; Potempa, J; Travis, J

    1994-01-01

    To elucidate the mechanism of production of an inflammatory exudate, gingival crevicular fluid (GCF), from periodontal pockets in periodontitis, we examined the vascular permeability enhancement (VPE) activity induced by an arginine-specific cysteine proteinase, Arg-gingipain-1 (RGP-1), produced by a major periopathogenic bacterium, Porphyromonas gingivalis. Intradermal injections into guinea pigs of RGP-1 (> 10(-8) M), or human plasma incubated with RGP-1 (> 10(-9) M), induced VPE in a dose- and activity-dependent manner but with different time courses for the two routes of production. VPE activity induced by RGP-1 was augmented by kininase inhibitors, inhibited by a kallikrein inhibitor and unaffected by an antihistamine drug. The VPE activity in human plasma incubated with RGP-1 also correlated closely with generation of bradykinin (BK). RGP-1 induced 30-40% less VPE activity in Hageman factor-deficient plasma and no VPE in plasma deficient in either prekallikrein (PK) or high molecular weight kininogen (HMWK). After incubation with RGP-1, plasma deficient in PK or HMWK, reconstituted with each missing protein, caused VPE, as did a mixture of purified PK and HMWK, but RGP-1 induced no VPE from HMWK. The VPE of extracts of clinically isolated P. gingivalis were reduced to about 10% by anti-RGP-1-IgG, leupeptin, or tosyl-L-lysine chloromethyl ketone, which paralleled effects observed with RGP-1. These results indicate that RGP-1 is the major VPE factor of P. gingivalis, inducing this activity through PK activation and subsequent BK release, resulting in GCF production at sites of periodontitis caused by infection with this organism. Images PMID:8040277

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

    Microsoft Academic Search

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

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

  18. Vascular involvement in rheumatic diseases: 'vascular rheumatology'

    Microsoft Academic Search

    Zoltán Szekanecz; Alisa E Koch

    2008-01-01

    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

  19. Carbohydrates and endothelial function: is a low-carbohydrate diet or a low-glycemic index diet favourable for vascular health?

    PubMed

    Jovanovski, Elena; Zurbau, Andreea; Vuksan, Vladimir

    2015-04-01

    Low-carbohydrate diets have become increasingly popular in both media and clinical research settings. Although they may improve some metabolic markers, their effects on arterial function remain unclear. Endothelial dysfunction is the well-established response to cardiovascular risk factors and a pivotal feature that precedes atherosclerotic diseases. It has been demonstrated that a high carbohydrate-induced hyperglycemia and subsequent oxidative stress acutely worsen the efficacy of the endothelial vasodilatory system. Thus, in theory, a carbohydrate restricted diet may preserve the integrity of the arterial system. This review attempts to provide insight on whether low-carbohydrate diets have a favorable or detrimental impact on vascular function, or it is perhaps the quality of carbohydrate that should direct dietary recommendations. Research to date suggests that diets low in carbohydrate amount may negatively impact vascular endothelial function. Conversely, it appears that maintaining recommended carbohydrate intake with utilization of low glycemic index foods generates a more favorable vascular profile. Understanding these relationships will aid in deciphering the diverging role of modulating quantity and quality of carbohydrates on cardiovascular risk. PMID:25954727

  20. Carbohydrates and Endothelial Function: Is a Low-Carbohydrate Diet or a Low-Glycemic Index Diet Favourable for Vascular Health?

    PubMed Central

    Jovanovski, Elena; Zurbau, Andreea

    2015-01-01

    Low-carbohydrate diets have become increasingly popular in both media and clinical research settings. Although they may improve some metabolic markers, their effects on arterial function remain unclear. Endothelial dysfunction is the well-established response to cardiovascular risk factors and a pivotal feature that precedes atherosclerotic diseases. It has been demonstrated that a high carbohydrate-induced hyperglycemia and subsequent oxidative stress acutely worsen the efficacy of the endothelial vasodilatory system. Thus, in theory, a carbohydrate restricted diet may preserve the integrity of the arterial system. This review attempts to provide insight on whether low-carbohydrate diets have a favorable or detrimental impact on vascular function, or it is perhaps the quality of carbohydrate that should direct dietary recommendations. Research to date suggests that diets low in carbohydrate amount may negatively impact vascular endothelial function. Conversely, it appears that maintaining recommended carbohydrate intake with utilization of low glycemic index foods generates a more favorable vascular profile. Understanding these relationships will aid in deciphering the diverging role of modulating quantity and quality of carbohydrates on cardiovascular risk. PMID:25954727

  1. Correlation between ankle brachial index, symptoms, and health-related quality of life in patients with peripheral vascular disease

    Microsoft Academic Search

    J. W. Long; J. G. Modrall; B. J. Parker; A. Swann; M. B. Welborn; T. Anthony

    2003-01-01

    Introduction: In the absence of quality of life measurement, other measures such as ABIs and patient symptoms provide a basis for determining the need for invasive therapy for patients with peripheral vascular disease (PVD). The accuracy of these surrogates in representing HRQL is, however, untested. The purpose of this study was to determine the correlation of these measures to HRQL.

  2. The Ketogenic Diet Alters the Hypoxic Response and Affects Expression of Proteins Associated with Angiogenesis, Invasive Potential and Vascular Permeability in a Mouse Glioma Model

    PubMed Central

    Woolf, Eric C.; Curley, Kara L.; Liu, Qingwei; Turner, Gregory H.; Charlton, Julie A.; Preul, Mark C.; Scheck, Adrienne C.

    2015-01-01

    Background The successful treatment of malignant gliomas remains a challenge despite the current standard of care, which consists of surgery, radiation and temozolomide. Advances in the survival of brain cancer patients require the design of new therapeutic approaches that take advantage of common phenotypes such as the altered metabolism found in cancer cells. It has therefore been postulated that the high-fat, low-carbohydrate, adequate protein ketogenic diet (KD) may be useful in the treatment of brain tumors. We have demonstrated that the KD enhances survival and potentiates standard therapy in a mouse model of malignant glioma, yet the mechanisms are not fully understood. Methods To explore the effects of the KD on various aspects of tumor growth and progression, we used the immunocompetent, syngeneic GL261-Luc2 mouse model of malignant glioma. Results Tumors from animals maintained on KD showed reduced expression of the hypoxia marker carbonic anhydrase 9, hypoxia inducible factor 1-alpha, and decreased activation of nuclear factor kappa B. Additionally, tumors from animals maintained on KD had reduced tumor microvasculature and decreased expression of vascular endothelial growth factor receptor 2, matrix metalloproteinase-2 and vimentin. Peritumoral edema was significantly reduced in animals fed the KD and protein analyses showed altered expression of zona occludens-1 and aquaporin-4. Conclusions The KD directly or indirectly alters the expression of several proteins involved in malignant progression and may be a useful tool for the treatment of gliomas. PMID:26083629

  3. Expansion Duroplasty Improves Intraspinal Pressure, Spinal Cord Perfusion Pressure, and Vascular Pressure Reactivity Index in Patients with Traumatic Spinal Cord Injury: Injured Spinal Cord Pressure Evaluation Study.

    PubMed

    Phang, Isaac; Werndle, Melissa C; Saadoun, Samira; Varsos, Georgios; Czosnyka, Marek; Zoumprouli, Argyro; Papadopoulos, Marios C

    2015-06-15

    We recently showed that, after traumatic spinal cord injury (TSCI), laminectomy does not improve intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), or the vascular pressure reactivity index (sPRx) at the injury site sufficiently because of dural compression. This is an open label, prospective trial comparing combined bony and dural decompression versus laminectomy. Twenty-one patients with acute severe TSCI had re-alignment of the fracture and surgical fixation; 11 had laminectomy alone (laminectomy group) and 10 had laminectomy and duroplasty (laminectomy+duroplasty group). Primary outcomes were magnetic resonance imaging evidence of spinal cord decompression (increase in intradural space, cerebrospinal fluid around the injured cord) and spinal cord physiology (ISP, SCPP, sPRx). The laminectomy and laminectomy+duroplasty groups were well matched. Compared with the laminectomy group, the laminectomy+duroplasty group had greater increase in intradural space at the injury site and more effective decompression of the injured cord. In the laminectomy+duroplasty group, ISP was lower, SCPP higher, and sPRx lower, (i.e., improved vascular pressure reactivity), compared with the laminectomy group. Laminectomy+duroplasty caused cerebrospinal fluid leak that settled with lumbar drain in one patient and pseudomeningocele that resolved completely in five patients. We conclude that, after TSCI, laminectomy+duroplasty improves spinal cord radiological and physiological parameters more effectively than laminectomy alone. PMID:25705999

  4. Vascular endothelial growth factors and angiogenesis in eye disease

    Microsoft Academic Search

    A. N. Witmer; G. F. J. M. Vrensen; C. J. F Van Noorden; R. O. Schlingemann

    2003-01-01

    The vascular endothelial growth factor (VEGF) family of growth factors controls pathological angiogenesis and increased vascular permeability in important eye diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). The purpose of this review is to develop new insights into the cell biology of VEGFs and vascular cells in angiogenesis and vascular leakage in general, and to provide

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

    PubMed

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

    2011-03-01

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

  6. Mechanisms of Tumor Vascular Priming by a Nanoparticulate Doxorubicin Formulation

    PubMed Central

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

    2013-01-01

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

  7. Lung and vascular function during chronic severe pulmonary ischemia

    PubMed Central

    Jenkins, John; Perino, Maria Grazia; Sukkar, Adlah; Mitzner, Wayne

    2011-01-01

    Bronchial vascular angiogenesis takes place in a variety of lung inflammatory conditions such as asthma, cystic fibrosis, lung cancer, and chronic pulmonary thromboembolic disease. However, it is unclear whether neovascularization is predominantly appropriate and preserves lung tissue or whether it contributes further to lung pathology through edema formation and inflammation. In the present study we examined airway and lung parenchymal function 14 days after left pulmonary artery ligation. In rats as well as higher mammals, severe pulmonary ischemia results in bronchial vascular proliferation. Using labeled microspheres, we demonstrated an 18-fold increase in systemic blood flow to the ischemic left lung. Additionally, vascular remodeling extended to the tracheal venules, which showed an average 28% increase in venular diameter. Despite this increase in vascularity, airways resistance was not altered nor was methacholine responsiveness. Since these measurements include the entire lung, we suggest that the normal right lung, which represented 78% of the total lung, obscured the ability to detect a change. When functional indexes such as diffusing capacity, in situ lung volume, and vascular permeability of the left lung could be separated from right lung, significant changes were observed. Thus when comparing average left lung values of rats 14 days after left pulmonary artery ligation to left lungs of rats undergoing sham surgery, diffusing capacity of the left lung decreased by 72%, left lung volume decreased by 38%, and the vascular permeability to protein increased by 58%. No significant differences in inflammatory cell recruitment were observed, suggesting that acute ischemic inflammation had resolved. We conclude that despite the preservation of lung tissue, the proliferating bronchial neovasculature may contribute to a sustained decrement in pulmonary function. PMID:21148340

  8. 3'-Deoxy-3'-[(18)F]-fluorothymidine ([(18)F]-FLT) transport in newly diagnosed glioma: correlation with nucleoside transporter expression, vascularization, and blood-brain barrier permeability.

    PubMed

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

    2013-10-01

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

  9. 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...

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

    PubMed

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

    2015-02-01

    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

  11. Vascular alterations in schwannoma

    PubMed Central

    Papiez, Joseph; Rojiani, Mumtaz V; Rojiani, Amyn M

    2014-01-01

    Schwannomas or neurilemmoma are benign peripheral nerve sheath tumors, which most frequently occur at the cerebellopontine angle. This morphologic study examines vascular alterations in these tumors, comparing them to other benign spindle cell neoplasms of the nervous system, while correlating these findings with evidence of vascular permeability. Thirty-four nervous system spindle cell neoplasms, sixteen schwannomas, nine fibroblastic/transitional meningiomas and nine peripheral neurofibromas were stained with H&E, Prussian-blue stain, and immunoreacted for factor VIII-related antigen and interstitial albumin. Schwannomas had focal clusters of vascular proliferation including groups of small thin-walled vessels, as well as larger vessels with extensive hyalinization. Neurofibromas and meningiomas almost uniformly had modest numbers of well-defined, thin walled individual vessels. Free hemosiderin and hemosiderin-laden macrophages were frequently identified in schwannomas. Prussian-blue stain for iron revealed focal or fairly widespread positivity in almost all schwannomas, only one meningioma and none of the neurofibromas. Immunoreaction for albumin demonstrated leakage of vascular proteins into the interstitium confirming tumor vessel permeability in schwannomas. Neither neurofibromas nor meningiomas displayed any detectable interstitial albumin. The above findings confirm a degree of reactive proliferation of vessels in schwannoma along with functional deficits in their vascular integrity with permeability to protein and blood. The presence of hyalinized vessels, hemosiderin, both free and within macrophages, and more readily evident Prussian blue staining, may provide an additional diagnostic clue in discriminating between histologically similar spindle cell lesions. The study however raises the possibility that these changes likely precede or facilitate the degenerative ‘ancient change’ seen in some schwannoma. PMID:25120781

  12. Vascular alterations in schwannoma.

    PubMed

    Papiez, Joseph; Rojiani, Mumtaz V; Rojiani, Amyn M

    2014-01-01

    Schwannomas or neurilemmoma are benign peripheral nerve sheath tumors, which most frequently occur at the cerebellopontine angle. This morphologic study examines vascular alterations in these tumors, comparing them to other benign spindle cell neoplasms of the nervous system, while correlating these findings with evidence of vascular permeability. Thirty-four nervous system spindle cell neoplasms, sixteen schwannomas, nine fibroblastic/transitional meningiomas and nine peripheral neurofibromas were stained with H&E, Prussian-blue stain, and immunoreacted for factor VIII-related antigen and interstitial albumin. Schwannomas had focal clusters of vascular proliferation including groups of small thin-walled vessels, as well as larger vessels with extensive hyalinization. Neurofibromas and meningiomas almost uniformly had modest numbers of well-defined, thin walled individual vessels. Free hemosiderin and hemosiderin-laden macrophages were frequently identified in schwannomas. Prussian-blue stain for iron revealed focal or fairly widespread positivity in almost all schwannomas, only one meningioma and none of the neurofibromas. Immunoreaction for albumin demonstrated leakage of vascular proteins into the interstitium confirming tumor vessel permeability in schwannomas. Neither neurofibromas nor meningiomas displayed any detectable interstitial albumin. The above findings confirm a degree of reactive proliferation of vessels in schwannoma along with functional deficits in their vascular integrity with permeability to protein and blood. The presence of hyalinized vessels, hemosiderin, both free and within macrophages, and more readily evident Prussian blue staining, may provide an additional diagnostic clue in discriminating between histologically similar spindle cell lesions. The study however raises the possibility that these changes likely precede or facilitate the degenerative 'ancient change' seen in some schwannoma. PMID:25120781

  13. Sequential delivery of vascular endothelial growth factor and sphingosine 1-phosphate for angiogenesis.

    PubMed

    Tengood, Jillian E; Kovach, Kyle M; Vescovi, Patrick E; Russell, Alan J; Little, Steven R

    2010-10-01

    Angiogenesis is an organized series of events, beginning with vessel destabilization, followed by endothelial cell re-organization, and ending with vessel maturation. Vascular endothelial growth factor (VEGF) aids in vascular permeability and endothelial cell recruitment while sphingosine 1-phosphate (S1P) stimulates vascular stability. Accordingly, VEGF may inhibit vessel stabilization while S1P may inhibit endothelial cell recruitment. For this reason, we created a new externally-regulated delivery model that not only permits sustained release of bioactive factors, but also temporal separation of the delivery of growth factors. Using this model, sequential delivery of factors was first confirmed in vitro with associated endothelial cells responding in a dose dependent manner. Furthermore, using a modified murine Matrigel plug model, it is apparent that delivery strategies where VEGF presentation is temporally separated from S1P presentation not only led to greater recruitment of endothelial cells, but also higher maturation index of associated vessels. PMID:20674008

  14. TRP Channels in Vascular Endothelial Cells

    Microsoft Academic Search

    Ching-On Wong; Xiaoqiang Yao

    \\u000a Endothelial cells regulate multiple vascular functions, such as vascular tone, permeability, remodeling, and angiogenesis.\\u000a It is known for long that cytosolic Ca2+ level ([Ca2+]i) and membrane potential of endothelial cells are crucial factors to initiate the signal transduction cascades, leading to\\u000a diverse vascular functions. Among the various kinds of endothelial ion channels that regulate ion homeostasis, transient receptor\\u000a potential (TRP)

  15. The role of vascular endothelial growth factor in pathological angiogenesis

    Microsoft Academic Search

    Napoleone Ferrara

    1995-01-01

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

  16. Vitrification media: toxicity, permeability, and dielectric properties.

    PubMed

    Wusteman, Monica C; Pegg, David E; Robinson, Martin P; Wang, Li-Hong; Fitch, Paul

    2002-02-01

    The aim of this study was to select a cryoprotectant for use in attempts to preserve tissues and organs by vitrification. The first step was to select a cell line with which to compare the toxicity of a range of commonly used cryoprotectants. An immortal vascular endothelial cell (ECV304) was exposed to vitrifying concentrations of four cryoprotectants: dimethyl sulfoxide (Me(2)SO; 45% w/w); 2,3 butanediol (BD; 32%); 1,2-propanediol (PD; 45%); and ethanediol (ED; 45%). Three times of exposure (1, 3, and 9 min) and two temperatures (22 and 2-4 degrees C) were studied. After removal of the cryoprotectant, the ability of the cells to adhere and divide in culture over a 2-day period was measured and expressed as a Cell Survival Index (CSI). There was no measurable loss of cells after exposure to the four cryoprotectants but 3-min exposure to BD, PD, or Me(2)SO at room temperature completely destroyed the ability of the cells to adhere and divide in culture. In contrast, exposure to all four cryoprotectants at 2-4 degrees C for up to 9 min permitted the retention of significant cell function, the CSIs, as a proportion of control, being 76.3+/-7.0% for BD, 63.6+/-7.1% for PD, 37.0+/-4.1 for Me(2)SO, and 33.2+/-3.0 for ED. The permeability properties of the cells for these four cryoprotectants was also measured at each temperature. Permeability to water was high, L(p) approximately equal 10(-7) cm/s/atm at 2-4 degrees C with all the cryoprotectants, but there were substantial differences in solute permeability: BD and PD were the most permeable at 2-4 degrees C (P(s)=4.1 and 3.0 x 10(-6) cm/s, respectively). Equilibration of intracellular cryoprotectant concentration was rapid, due in part to high water permeability; the cells were approximately 80% of their physiological volume after 10 min. Treatment at 2-4 degrees C with BD was the least damaging, but PD was not significantly worse. Exposure to vitrifying concentrations of ED and Me(2)SO, even at 2-4 degrees C, was severely damaging. Segments of rabbit carotid artery were treated with vitrifying concentrations of each of the two most favorable cryoprotectants, BD and PD, for 9 min. It was shown that each cryoprotectant reduced smooth muscle maximum contractility to a similar extent and abolished the acetylcholine response. However, vital staining revealed that exposure to BD also caused substantial damage to the endothelial lining, whereas the endothelium was completely intact after PD exposure, raising the possibility that the effect of PD on NO release may be reversible. In later stages of this project it is planned to use dielectric heating to rewarm the tissues and thereby avoid devitrification. The effects of each cryoprotectant on this mode of heating was therefore studied. Gelatin spheres containing vitrifiable concentrations of each cryoprotectant were rewarmed from -60 degrees C in a radiofrequency applicator. Because the uniformity of heating is related to the dielectric properties of the material, these properties were also measured. PD was the most suitable. These physical measurements, combined with the measurements of toxicity and permeability, indicate that PD is the most favorable cryoprotectant of those tested for use in subsequent stages of this study. PMID:12061845

  17. Vascular Dementia

    PubMed Central

    Ramos, Alberto R.; Dib, Salim I.; Wright, Clinton B.

    2013-01-01

    The purpose of this review is to highlight existing literature on the epidemiology, pathophysiology, and novel risk factors for vascular dementia. We further examine the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular diseases to the development of vascular dementia. In the elderly, in whom cerebral perfusion is diminished by the aging process, additional reduction in cerebral blood flow stemming from exposure to potentially modifiable vascular risk factors increases the probability of developing vascular dementia. Finally, we discuss the association between obstructive sleep apnea, an underrecognized risk factor for stroke, and vascular dementia. Obstructive sleep apnea is linked to cerebrovascular disease through many intermediary vascular risk factors and may directly cause cerebrovascular damage through microvacular disease. Insight into how cardiovascular risk factors induce vascular dementia offers an enhanced understanding of the multifactorial pathophysiology by this disorder and ways of preventing and managing the cerebrovascular precursors of vascular dementia. Many vital questions about the relation of obstructive sleep apnea with stroke and vascular dementia are still unanswered and await future well-designed studies.

  18. Vascular permeabilization by intravenous arachidonate in the rat peritoneal cavity: antagonism by antioxidants

    Microsoft Academic Search

    Miriam Alvarez-Guerra; Patrick Hannaert; Hamida Hider; Carlo Chiavaroli; Ricardo P Garay

    2003-01-01

    Arachidonic acid was investigated for its vascular permeabilizing potential in the rat peritoneal cavity and for its mechanism of action. The antagonistic potential of antioxidants (vitamin E, vitamin C and troxerutin) was also evaluated. Vascular permeability was equated to the rate of extravasation of Evans blue dye from plasma into the peritoneal cavity. Baseline permeability was linear up to 2

  19. Vascular Cures

    MedlinePLUS

    ... Project VOICE 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, ...

  20. Vascular Endothelial Growth Factor Induces Endothelial Fenestrations In Vitro

    Microsoft Academic Search

    Sybille Esser; Karen Wolburg; Hartwig Wolburg; Georg Breier; Teymuras Kurzchalia; Werner Risau

    1998-01-01

    Vascular endothelial growth factor (VEGF) is an important regulator of vasculogenesis, angiogene- sis, and vascular permeability. In contrast to its tran- sient expression during the formation of new blood ves- sels, VEGF and its receptors are continuously and highly expressed in some adult tissues, such as the kid- ney glomerulus and choroid plexus. This suggests that VEGF produced by the

  1. The fms-Like Tyrosine Kinase, a Receptor for Vascular Endothelial Growth Factor

    Microsoft Academic Search

    Carlie de Vries; Jaime A. Escobedo; Hikaru Ueno; Keith Houck; Napoleone Ferrara; Lewis T. Williams

    1992-01-01

    The fms-like tyrosine kinase (Flt) is a transmembrane receptor in the tyrosine kinase family. Expression of flt complementary DNA in COS cells conferred specific, high-affinity binding of vascular endothelial growth factor, also known as vascular permeability factor (VEGF-VPF), a factor that induces vascular permeability when injected in the guinea pig skin and stimulates endothelial cell proliferation. Expression of Flt in

  2. Vascular Calcification

    PubMed Central

    Demer, Linda L.; Tintut, Yin

    2009-01-01

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

  3. Metoclopramide and renal vascular resistance.

    PubMed

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

    1991-01-01

    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

  4. Mechanosensing at the Vascular Interface

    PubMed Central

    Tarbell, John M.; Simon, Scott I.; Curry, Fitz-Roy E.

    2015-01-01

    Mammals are endowed with a complex set of mechanisms that sense mechanical forces imparted by blood flow to endothelial cells (ECs), smooth muscle cells, and circulating blood cells to elicit biochemical responses through a process referred to as mechanotransduction. These biochemical responses are critical for a host of other responses, including regulation of blood pressure, control of vascular permeability for maintaining adequate perfusion of tissues, and control of leukocyte recruitment during immunosurveillance and inflammation. This review focuses on the role of the endothelial surface proteoglycan/glycoprotein layer—the glycocalyx (GCX)—that lines all blood vessel walls and is an agent in mechanotransduction and the modulation of blood cell interactions with the EC surface. We first discuss the biochemical composition and ultrastructure of the GCX, highlighting recent developments that reveal gaps in our understanding of the relationship between composition and spatial organization. We then consider the roles of the GCX in mechanotransduction and in vascular permeability control and review the prominent interaction of plasma borne sphingosine-1 phosphate (S1P), which has been shown to regulate both the composition of the GCX and the endothelial junctions. Finally, we consider the association of GCX degradation with inflammation and vascular disease and end with a final section on future research directions. PMID:24905872

  5. Iloprost attenuates the increased permeability in skeletal muscle after ischemia and reperfusion

    Microsoft Academic Search

    John Blebea; Robert A. Cambria; David DeFouw; Richard N. Feinberg; Robert W. Hobson; Walter N. Duran

    1990-01-01

    Increased vascular permeability is an early and sensitive indicator of ischemic muscle injury, occurring before significant histologic or radionuclide changes are evident. We investigated the effect of iloprost, a stable prostacyclin analog, on microvascular permeability in a rat striated muscle model. In six control and six experimental animals the cremaster muscle was dissected, placed in a closed-flow acrylic chamber, and

  6. Vascular ring

    MedlinePLUS

    ... following tests can help diagnose vascular ring: Chest x-ray Computed tomography (CT) scan of the heart and major blood vessels Camera down the throat to examine the airways (bronchoscopy) ... of heart X-ray of blood vessels (angiography) X-ray of the ...

  7. Permeability and relative permeability in rocks

    SciTech Connect

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

    1990-10-01

    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.

  8. Permeability of Dentine

    PubMed Central

    Ghazali, Farid Bin Che

    2003-01-01

    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

  9. 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 ...

  10. Vascular dementia

    PubMed Central

    Korczyn, Amos D; Vakhapova, Veronika; Grinberg, Lea T

    2012-01-01

    The epidemic grow of dementia causes great concern for the society. It is customary to consider Alzheimer’s disease (AD) as the most common cause of dementia, followed by vascular dementia (VaD). This dichotomous view of a neurodegenerative disease as opposed to brain damage caused by extrinsic factors led to separate lines of research in these two entities. Indeed, accumulated data suggest that the two disorders have additive effects and probably interact; however it is still unknown to what degree. Furthermore, epidemiological studies have shown “vascular” risk factors to be associated with AD. Therefore, a clear distinction between AD and VaD cannot be made in most cases, and is furthermore unhelpful. In the absence of efficacious treatment for the neurodegenerative process, special attention must be given to vascular component, even in patients with presumed mixed pathology. Symptomatic treatment of VaD and AD are similar, although the former is less effective. For prevention of dementia it is important to treat aggressively all factors, even in stroke survivors who do not show evidence of cognitive decline,. In this review, we will give a clinical and pathological picture of the processes leading to VaD and discuss it interaction with AD. PMID:22575403

  11. ConcepTest: Permeability

    NSDL National Science Digital Library

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

  12. [Vascular ultrasonography].

    PubMed

    Stiegler, H

    2012-03-01

    Vascular ultrasound plays an important role in the visual depiction of arteries, veins, and changes of tissue in lymphatic diseases. In the case of arteries, this ranges from endothelial dysfunction over measuring the increase of intima media thickness to the detection of stenoses, occlusion, or aneurysm. Ultrasound helps to differentiate in functional arterial diseases such as primary and secondary Raynaud's syndrome as well as arterial compression syndromes like entrapment syndrome of different arterial regions or the chronic exceptional compartment syndrome of the lower leg. Ultrasound plays a central role in the diagnosis of rare arterial diseases like large vessel vasculitis, arterial dissection, cystic adventitial degeneration, and the differentiation of vascular malformation especially in children, thus, permitting ultrasound-guided intervention and follow-up controls. In venous thrombosis, sonography is the primary imaging method, while follow-up controls help in the prediction of recurrent venous thrombosis. Ultrasound is a tool to determine the cause and severity of chronic venous insufficiency and allows different therapeutic procedures for the treatment of varicose veins to be visually monitored. PMID:22358939

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

    E-print Network

    Birdsey, Graeme M.; Shah, Aarti V.; Dufton, Neil; Reynolds, Louise E.; Almagro, Lourdes Osuna; 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

    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...

  14. Intraocular Hemorrhage Causes Retinal Vascular Dysfunction via Plasma Kallikrein

    PubMed Central

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

    2013-01-01

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

  15. The Role of Vascular Endothelial Growth Factor in Angiogenesis

    Microsoft Academic Search

    Napoleone Ferrara; Hans-Peter Gerber

    2001-01-01

    Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen and an angiogenic inducer as well as a mediator of vascular permeability. The biological effects of VEGF are mediated by two tyrosine kinase receptors, Flt-1 (VEGFr-1) and KDR (VEGFR-2). VEGF is essential for developmental angiogenesis and is also required for female reproductive functions and endochondral bone formation. Substantial evidence also

  16. Control of vascular permeability by polymorphonuclear leukocytes in inflammation

    Microsoft Academic Search

    Caroline V. Wedmore; T. J. Williams

    1981-01-01

    Polymorphonuclear leukocytes infiltrate tissues in response to an inflammatory stimulus to remove invading microorganisms and cell debris. We present evidence that these scavenging cells have another, more sophisticated role in that they are involved in the control of fluid efflux through the blood vessel wall which leads to tissue oedema.

  17. Oil reservoir permeability control

    SciTech Connect

    Chung, H.S.; Sampath, K.; Schwab, F.C.

    1987-03-31

    A method is described for controlling the permeability of a subterranean formation. The method comprises injecting into the formation an aqueous solution of a block copolymer having polar and non-polar segments. The polar segment is derived from a polymerized alkylene oxide and the non-polar segment from styrene or an alkylstyrene. The polar segments constitute at least 30 weight percent of the copolymer, thereby forming a gel of a strength sufficient to block the high permeability regions of the formation selectively.

  18. Wood smoke inhalation increases pulmonary microvascular permeability

    SciTech Connect

    Nieman, G.F.; Clark, W.R. Jr.; Goyette, D.; Hart, A.K.; Bredenberg, C.E.

    1989-04-01

    The effect of wood smoke inhalation (SI) on pulmonary vascular permeability was studied in open-chested, anesthetized dogs. Animals were divided into two groups. A prenodal lymphatic vessel was cannulated in group I (n = 7), and baseline (BL) lung lymph flow (QL) and lymph (CL) and plasma (CP) protein concentrations were measured. The animals' lungs were then ventilated with wood smoke for 5 minutes. Left atrial pressure (Pla) was increased above baseline (mean 16.7 +/- 2.2 mm Hg), and the ratio of CL to CP was used to assess endothelial permeability at high lymph flows. There was little change in either QL (BL: 27 +/- 9; SI: 27 +/- 5 microliters/min) or CL/CP (BL: 0.76 +/- 0.03; SI: 0.74 +/- 0.02) after SI at normal Pla. Elevation of Pla caused a significant increase in QL (136 +/- 15 microliters/min), but CL/CP (0.67 +/- 0.02) failed to decrease significantly at high lymph flows. In group II (n = 15) total protein concentration of airway fluid was compared with that of plasma after smoke inhalation, intravenous alloxan, and increased Pla. The ratio of protein concentration in airway fluid to plasma after SI (0.70 +/- 0.07) was greater than that obtained with increased Pla (0.64 +/- 0.07) but less than that after alloxan (0.85 +/- 0.04). These data indicate that SI in the dog results in a moderate increase in pulmonary vascular permeability that is less severe than that induced by alloxan.

  19. A drainage data-based calculation method for coalbed permeability

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  20. Relative Permeability Through Fractures

    E-print Network

    Stanford University

    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

  1. Intestinal permeability: An overview

    Microsoft Academic Search

    Ingvar Bjarnason; Andrew Macpherson; Daniel Hollander

    1995-01-01

    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

  2. The epidermal permeability barrier

    Microsoft Academic Search

    Lukas Landmann

    1988-01-01

    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

  3. 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...

  4. Design and development of multilayer vascular graft

    NASA Astrophysics Data System (ADS)

    Madhavan, Krishna

    2011-07-01

    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.

  5. Plant Vascular Biology 2013: vascular trafficking.

    PubMed

    Ursache, Robertas; Heo, Jung-Ok; Helariutta, Ykä

    2014-04-01

    About 200 researchers from around the world attended the Third International Conference on Plant Vascular Biology (PVB 2013) held in July 2013 at the Rantapuisto Conference Center, in Helsinki, Finland (http://www.pvb2013.org). The plant vascular system, which connects every organ in the mature plant, continues to attract the interest of researchers representing a wide range of disciplines, including development, physiology, systems biology, and computational biology. At the meeting, participants discussed the latest research advances in vascular development, long- and short-distance vascular transport and long-distance signalling in plant defence, in addition to providing a context for how these studies intersect with each other. The meeting provided an opportunity for researchers working across a broad range of fields to share ideas and to discuss future directions in the expanding field of vascular biology. In this report, the latest advances in understanding the mechanism of vascular trafficking presented at the meeting have been summarized. PMID:24431156

  6. Functional Vascular Endothelium Derived from Human Induced Pluripotent Stem Cells

    PubMed Central

    Adams, William J.; Zhang, Yuzhi; Cloutier, Jennifer; Kuchimanchi, Pranati; Newton, Gail; Sehrawat, Seema; Aird, William C.; Mayadas, Tanya N.; Luscinskas, Francis W.; García-Cardeña, Guillermo

    2013-01-01

    Summary Vascular endothelium is a dynamic cellular interface that displays a unique phenotypic plasticity. This plasticity is critical for vascular function and when dysregulated is pathogenic in several diseases. Human genotype-phenotype studies of endothelium are limited by the unavailability of patient-specific endothelial cells. To establish a cellular platform for studying endothelial biology, we have generated vascular endothelium from human induced pluripotent stem cells (iPSCs) exhibiting the rich functional phenotypic plasticity of mature primary vascular endothelium. These endothelial cells respond to diverse proinflammatory stimuli, adopting an activated phenotype including leukocyte adhesion molecule expression, cytokine production, and support for leukocyte transmigration. They maintain dynamic barrier properties responsive to multiple vascular permeability factors. Importantly, biomechanical or pharmacological stimuli can induce pathophysiologically relevant atheroprotective or atheroprone phenotypes. Our results demonstrate that iPSC-derived endothelium possesses a repertoire of functional phenotypic plasticity and is amenable to cell-based assays probing endothelial contributions to inflammatory and cardiovascular diseases. PMID:24052946

  7. Vascular permeabilization by intravenous arachidonate in the rat peritoneal cavity: antagonism by antioxidants.

    PubMed

    Alvarez-Guerra, Miriam; Hannaert, Patrick; Hider, Hamida; Chiavaroli, Carlo; Garay, Ricardo P

    2003-04-11

    Arachidonic acid was investigated for its vascular permeabilizing potential in the rat peritoneal cavity and for its mechanism of action. The antagonistic potential of antioxidants (vitamin E, vitamin C and troxerutin) was also evaluated. Vascular permeability was equated to the rate of extravasation of Evans blue dye from plasma into the peritoneal cavity. Baseline permeability was linear up to 2 h, with a rate constant (k) of 0.0031+/-0.0007 h(-1). Intravenous arachidonate (from 30 microg/kg to 3 mg/kg) induced an immediate, dose-related and significant increase in permeability (ranging from 80% to 150%), which was comparable to the effect induced by similar doses of serotonin. Aspirin (10 mg/kg) reduced the arachidonate-induced permeability by 75%, but interestingly neither the stable thromboxane A(2) receptor agonist U46619 (prostaglandin H(2) endoperoxide epoxymethane) nor prostacyclin was able to increase peritoneal vascular permeability. In contrast, the permeabilizing action of arachidonic acid was very sensitive to antioxidant agents. Thus, vitamin C and the flavonoid compound troxerutin (100 mg/kg) fully abolished arachidonate-induced permeability, whereas vitamin E had only a partial effect (40-100% inhibition). In conclusion, intravenous administration of arachidonic acid strongly enhanced peritoneal vascular permeability in the rat, apparently via free radical generation. This rat peritoneal model can be used to evaluate the in vivo antinflammatory potential of antioxidant drugs. PMID:12679157

  8. Society for Vascular Medicine

    MedlinePLUS

    ... 2015: Fellows Course Patient Information Pages from Vascular Medicine April 2015 Thrombophilia More info for patients. SVM ... 1, 2014 Archive Submit a Case New! Vascular Medicine Videos Dr. Bruce Gray talks about his article, ...

  9. Andes virus regulation of cellular microRNAs contributes to hantavirus-induced endothelial cell permeability.

    PubMed

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

    2010-11-01

    Hantaviruses infect human endothelial cells (ECs) and cause two diseases marked by vascular permeability defects, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Vascular permeability occurs in the absence of EC lysis, suggesting that hantaviruses alter normal EC fluid barrier functions. ECs infected by pathogenic hantaviruses are hyperresponsive to vascular endothelial growth factor (VEGF), and this alters the fluid barrier function of EC adherens junctions, resulting in enhanced paracellular permeability. Vascular permeability and VEGF-directed responses are determined by EC-specific microRNAs (miRNAs), which regulate cellular mRNA transcriptional responses. miRNAs mature within cytoplasmic processing bodies (P bodies), and the hantavirus nucleocapsid (N) protein binds RNA and localizes to P bodies, suggesting that hantaviruses may modify miRNA functions within infected ECs. Here we assessed changes in EC miRNAs following infection by the HPS-causing Andes hantavirus (ANDV). We analyzed 352 human miRNAs within ANDV-infected ECs using quantitative real-time (RT)-PCR arrays. Fourteen miRNAs, including six miRNAs that are associated with regulating vascular integrity, were upregulated >4-fold following infection by ANDV. Nine miRNAs were downregulated 3- to 3,400-fold following ANDV infection; these included miR-410, involved in regulating secretion, and miR-218, which is linked to the regulation of EC migration and vascular permeability. We further analyzed changes in miR-126, an EC-specific miRNA that regulates vascular integrity by suppressing SPRED1 and PIK3R2 mRNAs. While miR-126 levels were only slightly altered, we found that SPRED1 and PIK3R2 mRNA levels were increased 10- and 7-fold, respectively, in ANDV-infected ECs but were unaltered in ECs infected by the nonpathogenic Tula hantavirus (TULV). Consistent with increased SPRED1 expression, we found that the level of phospho-cofilin was decreased within ANDV-infected ECs. Moreover, small interfering RNA (siRNA) knockdown of SPRED1 dramatically decreased the permeability of ANDV-infected ECs in response to VEGF, suggesting that increased SPRED1 contributes to EC permeability following ANDV infection. These findings suggest that interference with normal miRNA functions contributes to the enhanced paracellular permeability of ANDV-infected ECs and that hantavirus regulation of miRNA functions is an additional determinant of hantavirus pathogenesis. PMID:20844033

  10. [Vascular anomalies: information documents].

    PubMed

    Philandrianos, C; Degardin, N; Casanova, D; Bardot, J; Petit, P; Bartoli, J-M; Magalon, G

    2011-06-01

    Vascular anomalies are a complex pathological group. They are composed of hemangiomas and other vascular tumors and congenital vascular malformations: venous, lymphatic, arteriovenous and capillary malformations. The management of these anomalies is difficult and must involve an interdisciplinary approach. To help patients to understand their pathology, we have made some information documents. PMID:20598795

  11. Biodiesel permeability in polyethylene

    NASA Astrophysics Data System (ADS)

    Richaud, Emmanuel; Fayolle, Bruno; Flaconnèche, Bruno; Verdu, Jacques

    2012-07-01

    This paper reports solubility, diffusivity and permeability data for soy and rapeseed methyl esters in polyethylene together with comparisons with methyl oleate and linoleate. The solubility was estimated on the order of 5% in weight at room temperature and increased up to more than 10% at 75°C. Diffusion kinetics obeys Fick's law and measured diffusion coefficient increased from 10-13 at room temperature to 5.10-11 m2 s-1 at 75°C. No significant difference was observed between all methyl esters under study. These data were used to discuss the reliability of predictive models for diffusion and solubility of additive type molecules into semi-crystalline thermoplastic polymers.

  12. Complexity in the vascular permeability factor\\/vascular endothelial growth factor (VPF\\/VEGF)-receptors signaling

    Microsoft Academic Search

    Debabrata Mukhopadhyay; Huiyan Zeng; Resham Bhattacharya

    2005-01-01

    The adult vasculature results from a network of vessels that is originally derived in the embryo by vasculogenesis, a process whereby vessels are formed de novo from endothelial cell (EC) precursors, known as angioblasts. During vasculogenesis, angioblasts proliferate and come together to form an initial network of vessels, also known as the primary capillary plexus. Sprouting and branching of new

  13. OPTIMAL AND EFFICIENT SEGMENTATION FOR 3D VASCULAR FOREST STRUCTURE WITH GRAPH CUTS

    E-print Network

    Chung, Albert C. S.

    to consider the bifurcations explicitly. Index Terms-- Graph Cuts, Optimal Segmentation, 3D Vascular Forest 1OPTIMAL AND EFFICIENT SEGMENTATION FOR 3D VASCULAR FOREST STRUCTURE WITH GRAPH CUTS Ning Zhu an optimal segmentation method for vascular forest structure based on graph cuts framework, which has widely

  14. Porosity and Permeability

    NSDL National Science Digital Library

    Rebecca Witherow

    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.

  15. Thrombin and vascular inflammation.

    PubMed

    Popovi?, Milan; Smiljani?, Katarina; Dobutovi?, Branislava; Syrovets, Tatiana; Simmet, Thomas; Isenovi?, Esma R

    2012-01-01

    Vascular endothelium is a key regulator of homeostasis. In physiological conditions it mediates vascular dilatation, prevents platelet adhesion, and inhibits thrombin generation. However, endothelial dysfunction caused by physical injury of the vascular wall, for example during balloon angioplasty, acute or chronic inflammation, such as in atherothrombosis, creates a proinflammatory environment which supports leukocyte transmigration toward inflammatory sites. At the same time, the dysfunction promotes thrombin generation, fibrin deposition, and coagulation. The serine protease thrombin plays a pivotal role in the coagulation cascade. However, thrombin is not only the key effector of coagulation cascade; it also plays a significant role in inflammatory diseases. It shows an array of effects on endothelial cells, vascular smooth muscle cells, monocytes, and platelets, all of which participate in the vascular pathophysiology such as atherothrombosis. Therefore, thrombin can be considered as an important modulatory molecule of vascular homeostasis. This review summarizes the existing evidence on the role of thrombin in vascular inflammation. PMID:21858738

  16. 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

  17. Marked Induction of the IAP Family Antiapoptotic Proteins Survivin and XIAP by VEGF in Vascular Endothelial Cells

    Microsoft Academic Search

    Jennifer Tran; Janusz Rak; Capucine Sheehan; Samuel D. Saibil; Eric LaCasse; Robert G. Korneluk; Robert S. Kerbel

    1999-01-01

    Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that has been shown to act as an endothelial cell mitogen as well as a vascular permeability factor. Several recent reports have also implicated VEGF as a major survival factor for endothelial cells during angiogenesis and vasculogenesis along with other growth factors such as bFGF and angiopoietin-1. VEGF has been

  18. Permeability within basaltic oceanic crust

    Microsoft Academic Search

    Andrew T. Fisher

    1998-01-01

    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

  19. Relative Permeability of Fractured Rock

    E-print Network

    Stanford University

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

  20. AKAP12 regulates vascular integrity in zebrafish

    PubMed Central

    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

    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

  1. AKAP12 regulates vascular integrity in zebrafish.

    PubMed

    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; Kim, Kyu-Won

    2012-03-31

    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

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

    PubMed Central

    DiStasi, Matthew R.; Ley, Klaus

    2009-01-01

    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

  3. Histamine Induces Vascular Hyperpermeability by Increasing Blood Flow and Endothelial Barrier Disruption In Vivo.

    PubMed

    Ashina, Kohei; Tsubosaka, Yoshiki; Nakamura, Tatsuro; Omori, Keisuke; Kobayashi, Koji; Hori, Masatoshi; Ozaki, Hiroshi; Murata, Takahisa

    2015-01-01

    Histamine is a mediator of allergic inflammation released mainly from mast cells. Although histamine strongly increases vascular permeability, its precise mechanism under in vivo situation remains unknown. We here attempted to reveal how histamine induces vascular hyperpermeability focusing on the key regulators of vascular permeability, blood flow and endothelial barrier. Degranulation of mast cells by antigen-stimulation or histamine treatment induced vascular hyperpermeability and tissue swelling in mouse ears. These were abolished by histamine H1 receptor antagonism. Intravital imaging showed that histamine dilated vasculature, increased blood flow, while it induced hyperpermeability in venula. Whole-mount staining showed that histamine disrupted endothelial barrier formation of venula indicated by changes in vascular endothelial cadherin (VE-cadherin) localization at endothelial cell junction. Inhibition of nitric oxide synthesis (NOS) by L-NAME or vasoconstriction by phenylephrine strongly inhibited the histamine-induced blood flow increase and hyperpermeability without changing the VE-cadherin localization. In vitro, measurements of trans-endothelial electrical resistance of human dermal microvascular endothelial cells (HDMECs) showed that histamine disrupted endothelial barrier. Inhibition of protein kinase C (PKC) or Rho-associated protein kinase (ROCK), NOS attenuated the histamine-induced barrier disruption. These observations suggested that histamine increases vascular permeability mainly by nitric oxide (NO)-dependent vascular dilation and subsequent blood flow increase and maybe partially by PKC/ROCK/NO-dependent endothelial barrier disruption. PMID:26158531

  4. Histamine Induces Vascular Hyperpermeability by Increasing Blood Flow and Endothelial Barrier Disruption In Vivo

    PubMed Central

    Ashina, Kohei; Tsubosaka, Yoshiki; Nakamura, Tatsuro; Omori, Keisuke; Kobayashi, Koji; Hori, Masatoshi; Ozaki, Hiroshi; Murata, Takahisa

    2015-01-01

    Histamine is a mediator of allergic inflammation released mainly from mast cells. Although histamine strongly increases vascular permeability, its precise mechanism under in vivo situation remains unknown. We here attempted to reveal how histamine induces vascular hyperpermeability focusing on the key regulators of vascular permeability, blood flow and endothelial barrier. Degranulation of mast cells by antigen-stimulation or histamine treatment induced vascular hyperpermeability and tissue swelling in mouse ears. These were abolished by histamine H1 receptor antagonism. Intravital imaging showed that histamine dilated vasculature, increased blood flow, while it induced hyperpermeability in venula. Whole-mount staining showed that histamine disrupted endothelial barrier formation of venula indicated by changes in vascular endothelial cadherin (VE-cadherin) localization at endothelial cell junction. Inhibition of nitric oxide synthesis (NOS) by L-NAME or vasoconstriction by phenylephrine strongly inhibited the histamine-induced blood flow increase and hyperpermeability without changing the VE-cadherin localization. In vitro, measurements of trans-endothelial electrical resistance of human dermal microvascular endothelial cells (HDMECs) showed that histamine disrupted endothelial barrier. Inhibition of protein kinase C (PKC) or Rho-associated protein kinase (ROCK), NOS attenuated the histamine-induced barrier disruption. These observations suggested that histamine increases vascular permeability mainly by nitric oxide (NO)-dependent vascular dilation and subsequent blood flow increase and maybe partially by PKC/ROCK/NO-dependent endothelial barrier disruption. PMID:26158531

  5. Ceramide alters endothelial cell permeability by a nonapoptotic mechanism

    PubMed Central

    Lindner, Karsten; Uhlig, Ulrike; Uhlig, Stefan

    2005-01-01

    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

  6. Cyclic Stretch, Reactive Oxygen Species, and Vascular Remodeling

    PubMed Central

    2009-01-01

    Abstract Blood vessels respond to changes in mechanical load from circulating blood in the form of shear stress and mechanical strain as the result of heart propulsions by changes in intracellular signaling leading to changes in vascular tone, production of vasoactive molecules, and changes in vascular permeability, gene regulation, and vascular remodeling. In addition to hemodynamic forces, microvasculature in the lung is also exposed to stretch resulting from respiratory cycles during autonomous breathing or mechanical ventilation. Among various cell signaling pathways induced by mechanical forces and reported to date, a role of reactive oxygen species (ROS) produced by vascular cells receives increasing attention. ROS play an essential role in signal transduction and physiologic regulation of vascular function. However, in the settings of chronic hypertension, inflammation, or acute injury, ROS may trigger signaling events that further exacerbate smooth muscle hypercontractility and vascular remodeling associated with hypertension and endothelial barrier dysfunction associated with acute lung injury and pulmonary edema. These conditions are also characterized by altered patterns of mechanical stimulation experienced by vasculature. This review will discuss signaling pathways regulated by ROS and mechanical stretch in the pulmonary and systemic vasculature and will summarize functional interactions between cyclic stretch- and ROS-induced signaling in mechanochemical regulation of vascular structure and function. Antioxid. Redox Signal. 11, 1651–1667. PMID:19186986

  7. Vascular ring diagnosis following respiratory arrest.

    PubMed

    Robson, Evie Alexandra; Scott, Alison; Chetcuti, Philip; Crabbe, David

    2014-01-01

    Vascular rings can present with non-specific respiratory and/or oesophageal symptoms. Early diagnosis requires a high index of suspicion. This case report describes an uncommon acute presentation of a vascular ring. We report a thriving 14-month-old child with a long history of recurrent wheeze and 'noisy breathing'. He presented acutely with food bolus impaction in the oesophagus which led to a respiratory arrest. Oesophagoscopy and bronchoscopy suggested vascular ring anomaly. A contrast-enhanced CT scan demonstrated a right-sided aortic arch with left ligamentum arteriosum encircling the oesophagus and airway. The ligament was ligated and divided. At follow-up 6?months later, the infant had mild persistent stridor but was otherwise well. PMID:24895385

  8. Increased capillary permeability mediated by a dengue virus-induced lymphokine.

    PubMed Central

    Khanna, M; Chaturvedi, U C; Sharma, M C; Pandey, V C; Mathur, A

    1990-01-01

    The mechanism of increased capillary permeability, seen in cases of dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS), is not known. Dengue type 2 virus (DV) is known to induce production of a lymphokine, the cytotoxic factor (CF), by the T lymphocytes of mouse spleen. The data presented here show that intraperitoneal inoculation of CF in mice results in increased capillary permeability in a dose-dependent manner, as shown by leakage of intravenously injected radiolabelled iodine (125I) or Evans blue dye. Peak leakage occurred 30 min after inoculation of CF and the vascular integrity was restored by 2 hr. The increase in capillary permeability was abrogated by pretreatment of mice with anti-CF antibodies, avil (H1 receptor blocker) or ranitidine (H2 receptor blocker). The findings thus show that a DV-induced lymphokine, the CF, increases the capillary permeability via release of histamine. PMID:2312168

  9. Geothermal Permeability Enhancement - Final Report

    SciTech Connect

    Joe Beall; Mark Walters

    2009-06-30

    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.

  10. Endothelial injury in the initiation and progression of vascular disorders

    Microsoft Academic Search

    Belay Tesfamariam; Albert F. DeFelice

    2007-01-01

    Endothelial cell dysfunction is considered to be an early event which subsequently leads to vascular wall disorders. Ultrastructural studies indicate that the endothelial cell changes involve membrane damage, increased permeability, swelling and necrosis. The endothelial cell loss of function could be as a result of changes in hemodynamic forces (shear and\\/or hoop stress), direct drug-induced cytotoxicity, mechanical device implant-induced injury

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

    PubMed

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

    2015-01-01

    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

  12. Simultaneous imaging of tumor oxygenation and microvascular permeability using Overhauser enhanced MRI

    PubMed Central

    Matsumoto, Shingo; Yasui, Hironobu; Batra, Sonny; Kinoshita, Yuichi; Bernardo, Marcelino; Munasinghe, Jeeva P.; Utsumi, Hideo; Choudhuri, Rajani; Devasahayam, Nallathamby; Subramanian, Sankaran; Mitchell, James B.; Krishna, Murali C.

    2009-01-01

    Architectural and functional abnormalities of blood vessels are a common feature in tumors. A consequence of increased vascular permeability and concomitant aberrant blood flow is poor delivery of oxygen and drugs, which is associated with treatment resistance. In the present study, we describe a strategy to simultaneously visualize tissue oxygen concentration and microvascular permeability by using a hyperpolarized 1H-MRI, known as Overhauser enhanced MRI (OMRI), and an oxygen-sensitive contrast agent OX63. Substantial MRI signal enhancement was induced by dynamic nuclear polarization (DNP). The DNP achieved up to a 7,000% increase in MRI signal at an OX63 concentration of 1.5 mM compared with that under thermal equilibrium state. The extent of hyperpolarization is influenced mainly by the local concentration of OX63 and inversely by the tissue oxygen level. By collecting dynamic OMRI images at different hyperpolarization levels, local oxygen concentration and microvascular permeability of OX63 can be simultaneously determined. Application of this modality to murine tumors revealed that tumor regions with high vascular permeability were spatio-temporally coincident with hypoxia. Quantitative analysis of image data from individual animals showed an inverse correlation between tumor vascular leakage and median oxygen concentration. Immunohistochemical analyses of tumor tissues obtained from the same animals after OMRI experiments demonstrated that lack of integrity in tumor blood vessels was associated with increased tumor microvascular permeability. This dual imaging technique may be useful for the longitudinal assessment of changes in tumor vascular function and oxygenation in response to chemotherapy, radiotherapy, or antiangiogenic treatment. PMID:19815528

  13. Simultaneous imaging of tumor oxygenation and microvascular permeability using Overhauser enhanced MRI.

    PubMed

    Matsumoto, Shingo; Yasui, Hironobu; Batra, Sonny; Kinoshita, Yuichi; Bernardo, Marcelino; Munasinghe, Jeeva P; Utsumi, Hideo; Choudhuri, Rajani; Devasahayam, Nallathamby; Subramanian, Sankaran; Mitchell, James B; Krishna, Murali C

    2009-10-20

    Architectural and functional abnormalities of blood vessels are a common feature in tumors. A consequence of increased vascular permeability and concomitant aberrant blood flow is poor delivery of oxygen and drugs, which is associated with treatment resistance. In the present study, we describe a strategy to simultaneously visualize tissue oxygen concentration and microvascular permeability by using a hyperpolarized (1)H-MRI, known as Overhauser enhanced MRI (OMRI), and an oxygen-sensitive contrast agent OX63. Substantial MRI signal enhancement was induced by dynamic nuclear polarization (DNP). The DNP achieved up to a 7,000% increase in MRI signal at an OX63 concentration of 1.5 mM compared with that under thermal equilibrium state. The extent of hyperpolarization is influenced mainly by the local concentration of OX63 and inversely by the tissue oxygen level. By collecting dynamic OMRI images at different hyperpolarization levels, local oxygen concentration and microvascular permeability of OX63 can be simultaneously determined. Application of this modality to murine tumors revealed that tumor regions with high vascular permeability were spatio-temporally coincident with hypoxia. Quantitative analysis of image data from individual animals showed an inverse correlation between tumor vascular leakage and median oxygen concentration. Immunohistochemical analyses of tumor tissues obtained from the same animals after OMRI experiments demonstrated that lack of integrity in tumor blood vessels was associated with increased tumor microvascular permeability. This dual imaging technique may be useful for the longitudinal assessment of changes in tumor vascular function and oxygenation in response to chemotherapy, radiotherapy, or antiangiogenic treatment. PMID:19815528

  14. Peripheral Vascular Malformations

    Microsoft Academic Search

    Peter Littler; Peter Rowlands

    \\u000a Peripheral vascular malformations are uncommon lesions and are thought to be due to a focal persistence of primitive vascular\\u000a elements.\\u000a \\u000a \\u000a Vascular malformations are not neoplastic. They are subdivided into high-flow and low-flow lesions. High-flow lesions are\\u000a arterial; low-flow lesions are venous, capillary, or lymphatic.\\u000a \\u000a \\u000a \\u000a It is important that these lesions are evaluated and treated by a specialist with experience in

  15. Neurogenic and vascular claudication.

    PubMed

    Hawkes, C H; Roberts, G M

    1978-10-01

    Intermittent claudication from peripheral vascular disease is sometimes difficult to distinguish from similar claudication due to degenerative disease of the lumbar spine. In the present study 26 patients with vascular disease were compared with 23 patients with lumbar degenerative disease. Assessment was by clinical and radiological examination. In the vascular group characteristic distinguishing features were: abnormal foot pulses, arterial bruits, relief of symptoms by standing, a constant claudicating distance and stocking sensory loss. In the lumbar group typical findings were: discomfort on lifting, bending, coughing or sneezing, pain on standing, history of back injury, variable claudicating distance and segmental sensory loss. PMID:731261

  16. Iloprost attenuates the increased permeability in skeletal muscle after ischemia and reperfusion

    SciTech Connect

    Blebea, J.; Cambria, R.A.; DeFouw, D.; Feinberg, R.N.; Hobson, R.W. 2d.; Duran, W.N. (Univ. of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark (USA))

    1990-12-01

    Increased vascular permeability is an early and sensitive indicator of ischemic muscle injury, occurring before significant histologic or radionuclide changes are evident. We investigated the effect of iloprost, a stable prostacyclin analog, on microvascular permeability in a rat striated muscle model. In six control and six experimental animals the cremaster muscle was dissected, placed in a closed-flow acrylic chamber, and suffused with a bicarbonate buffer solution. Dextran labeled with fluorescein was injected intravenously as a macromolecular tracer, and microvascular permeability was determined on the basis of clearance of the fluorescent tracer. Two hours of ischemia were followed by 2 hours of reperfusion. In the experimental group iloprost (0.5 microgram/kg/min) was given in a continuous intravenous infusion. Microvascular permeability increased significantly during reperfusion in both control and experimental animals (p less than 0.0001). Treatment with iloprost, however, significantly attenuated this response compared to the control group, 4.8 +/- 0.3 versus 7.3 +/- 0.5 microliters/gm/min, respectively (p less than 0.0001). Iloprost decreases the rise in vascular permeability after ischemia and reperfusion. Experimental clinical use of iloprost under controlled conditions in the treatment of patients with acute skeletal muscle ischemia appears justified.

  17. Pyrotechnic deflagration velocity and permeability

    SciTech Connect

    Begeal, D R; Stanton, P L

    1982-01-01

    Particle size, porosity, and permeability of the reactive material have long been considered to be important factors in propellant burning rates and the deflagration-to-detonation transition in explosives. It is reasonable to assume that these same parameters will also affect the deflagration velocity of pyrotechnics. This report describes an experimental program that addresses the permeability of porous solids (particulate beds), in terms of particle size and porosity, and the relationship between permeability and the behavior of pyrotechnics and explosives. The experimental techniques used to acquire permeability data and to characterize the pyrotechnic burning are discussed. Preliminary data have been obtained on the burning characteristics of titanium hydride/potassium perchlorate (THKP) and boron/calcium chromate (BCCR). With THKP, the velocity of a pressure wave (from hot product gases) in the unburned region shows unsteady behavior which is related to the initial porosity or permeability. Simultaneous measurements with pressure gauges and ion gauges reveal that the pressure wave precedes the burn front. Steady burning of BCCR was observed with pressure gauge diagnostics and with a microwave interferometry technique.

  18. Vascular Disease Foundation

    MedlinePLUS

    ... Project VOICE 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, ...

  19. Diabetes and Vascular Disease

    MedlinePLUS

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

  20. 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, ...

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

    E-print Network

    Ning, Xiuxu

    1989-01-01

    in their experiment was eight feet in length and two inches in diameter. The pressure transient was observed and recorded as it traveled through the sample. The values of interest at the core face were the maximum pulse pressure, pulse duration and the inlet... Permeability . . Conventional Methods of Measuring Relative Permeability. . . . Pulse Decay Technique for Determining Absolute Permeabilities Relative Permeability Measurement with Low Permeability Cores Effect of Net Stress Cycling on Permeability...

  2. Permeability enhancement by shock cooling

    NASA Astrophysics Data System (ADS)

    Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

    2015-04-01

    The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of granitic geothermal reservoirs.

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

    SciTech Connect

    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

    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.

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

    PubMed

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

    2015-03-01

    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

  5. Contrasting Effects of Hypochlorous Acid and Hydrogen Peroxide on Endothelial Permeability Prevention with cAMP Drugs

    Microsoft Academic Search

    LUIS OCHOA; GREGORY WAYPA; JOHN R. MAHONEY; LUIS RODRIGUEZ; FRED L. MINNEAR

    Activated polymorphonuclear leukocytes generate a cascade of reduced oxygen metabolites. In addi- tion to their antimicrobial role, hydrogen peroxide (H 2 O 2 ) and hypochlorous acid (HOCl) function as inflammatory mediators and increase the protein permeability of the vascular endothelium. The ob- jectives of the present study were to compare the effects of H 2 O 2 and HOCl

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

    PubMed Central

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

    2013-01-01

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

  7. Vascular permeabilization by intravenous arachidonate in the rat peritoneal cavity: antagonism by ethamsylate

    Microsoft Academic Search

    Patrick Hannaert; Miriam Alvarez-Guerra; Hamida Hider; Carlo Chiavaroli; Ricardo P Garay

    2003-01-01

    The hemostatic agent, ethamsylate, inhibits arachidonic acid metabolism by a mechanism independent of cyclooxygenase activity and blocks carrageenan-induced rat paw edema. Here, ethamsylate was investigated for (i) in vivo actions on the free radical-dependent, permeabilizing responses to arachidonic acid and (ii) its antioxidant potential in vitro. Vascular permeability was equated to the extravasation rate of Evans blue from plasma into

  8. Tumor vascular targeted liposomal-bortezomib minimizes side effects and increases therapeutic activity in human neuroblastoma.

    PubMed

    Zuccari, Guendalina; Milelli, Andrea; Pastorino, Fabio; Loi, Monica; Petretto, Andrea; Parise, Amelia; Marchetti, Chiara; Minarini, Anna; Cilli, Michele; Emionite, Laura; Di Paolo, Daniela; Brignole, Chiara; Piaggio, Francesca; Perri, Patrizia; Tumiatti, Vincenzo; Pistoia, Vito; Pagnan, Gabriella; Ponzoni, Mirco

    2015-08-10

    Neuroblastoma is a childhood cancer with poor long-term prognosis in advanced stages. A major aim in neuroblastoma therapy is to develop targeted drug delivery systems to ameliorate drug therapeutic index and efficacy. In this study, a novel bortezomib (BTZ) liposomal formulation was set-up and characterized. Since BTZ is freely permeable across the lipidic bilayer, an amino-lactose (LM) was synthesized as complexing agent to entrap BTZ inside the internal aqueous compartment of stealth liposomes. High encapsulation efficiency was achieved by a loading method based on the formation of boronic esters between the boronic acid moiety of BTZ and the hydroxyl groups of LM. Next, NGR peptides were linked to the liposome surface as a targeting-ligand for the tumor endothelial cell marker, aminopeptidase N. Liposomes were characterized for size, Z-potential, polydispersity index, drug content, and release. Lyophilization in the presence of cryoprotectants (trehalose, sucrose) was also examined in terms of particle size changes and drug leakage. BTZ was successfully loaded into non-targeted (SL[LM-BTZ]) and targeted (NGR-SL[LM-BTZ]) liposomes with an entrapment efficiency of about 68% and 57%, respectively. These nanoparticles were suitable for intravenous administration, presenting an average diameter of 170nm and narrow polydispersity. Therefore, orthotopic NB-bearing mice were treated with 1.0 or 1.5mg/kg of BTZ, either in free form or encapsulated into liposomes. BTZ loaded liposomes showed a significant reduction of drug systemic adverse effects with respect to free drug, even at the highest dose tested. Moreover, mice treated with 1.5mg/kg of NGR-SL[LM-BTZ] lived statistically longer than untreated mice (P=0.0018) and SL[LM-BTZ]-treated mice (P=0.0256). Our results demonstrate that the novel vascular targeted BTZ formulation is endowed with high therapeutic index and low toxicity, providing a new tool for future applications in neuroblastoma clinical studies. PMID:26031842

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

    PubMed

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

    2014-10-01

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

  10. Diffusion and Osmosis Selectively Permeable

    E-print Network

    Rose, Michael R.

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

  11. The Permeability of Porous Materials

    Microsoft Academic Search

    E. C. Childs; N. Collis-George

    1950-01-01

    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

  12. Permeable Pavement Research ? Edison, NJ

    EPA Science Inventory

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

  13. Endothelial Cell Permeability and Adherens Junction Disruption Induced by Junín Virus Infection

    PubMed Central

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

    2014-01-01

    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

  14. Experimental Determination of the Permeability in the Lacunar-Canalicular Porosity of Bone

    PubMed Central

    Gailani, Gaffar; Benalla, Mohammed; Mahamud, Rashal; Cowin, Stephen C.; Cardoso, Luis

    2010-01-01

    Permeability of the mineralized bone tissue is a critical element in understanding fluid flow occurring in the lacunar-canalicular porosity (PLC) compartment of bone and its role in bone nutrition and mechanotransduction. However, the estimation of bone permeability at the tissue level is affected by the influence of the vascular porosity (PV) in macroscopic samples containing several osteons. In this communication, both analytical and experimental approaches are proposed to estimate the lacunar-canalicular permeability in a single osteon. Data from an experimental stress-relaxation test in a single osteon is used to derive the PLC permeability by curve fitting to theoretical results from a compressible transverse isotropic poroelastic model of a porous annular disk under a ramp loading history (Cowin and Mehrabadi 2007; Gailani and Cowin 2008). The PLC tissue intrinsic permeability in the radial direction of the osteon was found to be dependent on the strain rate used and within the range of O(10?24)?O(10?25). The reported values of PLC permeability are in reasonable agreement with previously reported values derived using FEA and nanoindentation approaches. PMID:19831477

  15. Permeability of compacting porous lavas

    NASA Astrophysics Data System (ADS)

    Ashwell, P. A.; Kendrick, J. E.; Lavallée, Y.; Kennedy, B. M.; Hess, K.-U.; Aulock, F. W.; Wadsworth, F. B.; Vasseur, J.; Dingwell, D. B.

    2015-03-01

    The highly transient nature of outgassing commonly observed at volcanoes is in part controlled by the permeability of lava domes and shallow conduits. Lava domes generally consist of a porous outer carapace surrounding a denser lava core with internal shear zones of variable porosity. Here we examine densification using uniaxial compression experiments on variably crystalline and porous rhyolitic dome lavas from the Taupo Volcanic Zone. Experiments were conducted at 900°C and an applied stress of 3 MPa to 60% strain, while monitoring acoustic emissions to track cracking. The evolution of the porous network was assessed via X-ray computed tomography, He-pycnometry, and relative gas permeability. High starting connected porosities led to low apparent viscosities and high strain rates, initially accompanied by abundant acoustic emissions. As compaction ensued, the lavas evolved; apparent viscosity increased and strain rate decreased due to strain hardening of the suspensions. Permeability fluctuations resulted from the interplay between viscous flow and brittle failure. Where phenocrysts were abundant, cracks had limited spatial extent, and pore closure decreased axial and radial permeability proportionally, maintaining the initial anisotropy. In crystal-poor lavas, axial cracks had a more profound effect, and permeability anisotropy switched to favor axial flow. Irrespective of porosity, both crystalline samples compacted to a threshold minimum porosity of 17-19%, whereas the crystal-poor sample did not achieve its compaction limit. This indicates that unconfined loading of porous dome lavas does not necessarily form an impermeable plug and may be hindered, in part by the presence of crystals.

  16. Increased microvascular water permeability in patients with septic shock, assessed with venous congestion plethysmography (VCP)

    Microsoft Academic Search

    F. Christ; J. Gamble; I. B. Gartside; W. J. Kox

    1998-01-01

    Objectives: To investigate microvascular water permeability (filtration capacity, Kf) in patients with septic and non-septic shock using a new non-invasive method for studying microvascular parameters in man.\\u000a Setting: Intensive Care Unit of a university hospital. Patients and methods: We investigated 28 patients, presenting with cardio-vascular instability due to either septic shock, or non-septic shock\\u000a (haemorrhage, multiple trauma, respiratory and\\/or cardiac

  17. Regulation of endothelial permeability in the primate corpora lutea: implications for ovarian hyperstimulation syndrome.

    PubMed

    Herr, Daniel; Bekes, Inga; Wulff, Christine

    2015-02-01

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

  18. 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.

  19. Screening for peripheral vascular disease with a simple oscillometric blood pressure equipment

    Microsoft Academic Search

    Niels Wiinberg; Jesper Mehlsen

    2001-01-01

    The aim of the study was to test if an automated blood pressure measuring device could be used as a simple screening test for peripheral vascular disease. Blood pressure at the ankle level is a good predictor of vascular disease in the lower limbs. The ankle\\/arm index (AAI), i.e. the ratio between the ankle systolic blood pressure and arm (brachial)

  20. Structure/Permeability Relationships Of Polyimide Membranes

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  1. STEAM-WATER RELATIVE PERMEABILITY A DISSERTATION

    E-print Network

    Stanford University

    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

  2. Vapor-liquid phase separator permeability results

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  3. Radial flow permeability measurement. Part A: Theory

    Microsoft Academic Search

    J. R. Weitzenböck; R. A. Shenoi; P. A. Wilson

    1999-01-01

    This paper deals with permeability measurement in the context of Resin Transfer Moulding (RTM). A new approach to two-dimensional radial flow permeability measurement with constant inlet pressure is proposed. It allows principal permeability to be measured even if the experimental axes are not aligned with the principal direction. This part of the paper looks at the underlying theory of the

  4. Compression flow permeability measurement: a continuous technique

    Microsoft Academic Search

    M. J. Buntain; S. Bickerton

    2003-01-01

    Existing permeability measurement techniques are based upon pressure driven flow through fibrous reinforcing materials. An innovative method is presented here utilising compression driven flow, which allows for continuous measurement of permeability over wide fibre volume fraction ranges, in a single efficient test. The initial study has been limited to isotropic reinforcements, obtained permeability data being compared with values measured using

  5. Endothelial injury in the initiation and progression of vascular disorders.

    PubMed

    Tesfamariam, Belay; DeFelice, Albert F

    2007-04-01

    Endothelial cell dysfunction is considered to be an early event which subsequently leads to vascular wall disorders. Ultrastructural studies indicate that the endothelial cell changes involve membrane damage, increased permeability, swelling and necrosis. The endothelial cell loss of function could be as a result of changes in hemodynamic forces (shear and/or hoop stress), direct drug-induced cytotoxicity, mechanical device implant-induced injury and/or immune-mediated mechanisms. Drugs may perturb endothelial cell integrity by directly triggering inflammatory signaling cascades, enhancing expression of cellular adhesion molecules, activation of cytotoxic T cells and/or autoantibodies directed against endothelial cell membranes. Local release of inflammatory cytokines and chemokines activate endothelial cells to upregulate soluble adhesion molecules, activate neutrophils and generate reactive oxygen species which serve to amplify the initial inflammation leading to dysregulated apoptosis, secondary necrosis and overt vascular injury lesions. Considering the role of the endothelium in the initiation and propagation of vascular wall injury, there is a need for the discovery of validated biomarkers to serve as a predictor of activation of inflammatory cascades in the development of vascular injury. This article reviews some aspects of the multifaceted mechanisms that lead to the initial endothelial cell disruption and subsequent vascular wall injury. PMID:17218160

  6. Vascularized epiphyseal transplant.

    PubMed

    Innocenti, Marco; Delcroix, Luca; Romano, G Federico; Capanna, Rodolfo

    2007-01-01

    In skeletally immature patients, the transfer of vascularized epiphysis along with a variable amount of adjoining diaphysis may provide the potential for growth of such a graft, preventing future limb length discrepancy. This article describes the authors' experience with the vascularized transfer of the proximal fibular epiphysis in the reconstruction of large bone defects including the epiphysis in a series of 27 patients ranging in age from 2 to 11 years. The follow-up, ranging from 2 to 14 years, has been long enough to allow some evaluation of the validity, indications, and limits of this reconstructive option. PMID:17145298

  7. Building Vascular Networks

    PubMed Central

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

    2013-01-01

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

  8. Preeclampsia does not alter vascular growth and expression of CD31 and vascular endothelial cadherin in human placentas.

    PubMed

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

    2015-01-01

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

  9. Tumor angiogenesis and accessibility: role of vascular endothelial growth factor.

    PubMed

    Jain, Rakesh K

    2002-12-01

    Solid tumors consist of several components, including normal and stromal cells, extracellular matrix, and vasculature. To grow and metastasize, tumors must stimulate the development of new vasculature through a process known as angiogenesis. Unlike normal blood vessels, tumor blood vessels are chaotic, irregular, and leaky, which leads to uneven delivery of nutrients and therapeutic agents to the tumor. Conventional therapies target neoplastic cells within a tumor; however, tumor vasculature is emerging as an important target for anticancer therapy. Antiangiogenic therapy offers several potential advantages as an approach to cancer treatment, notably physical accessibility and genetic stability of target cells. Vascular endothelial growth factor (VEGF), a central mediator of angiogenesis, has emerged as an important target for antiangiogenic therapy. In preclinical studies, treatment of human tumor xenografts in immunodeficient mice with the anti-VEGF monoclonal antibody A4.6.1 led to reduced tumor vessel permeability and caused vascular regression. The reduced vascular permeability, resulting from inhibition of VEGF, led to increased delivery of oxygen and therapeutic agents to tumors. Anti-VEGF therapy was effectively combined with other treatment modalities, including radiation, antihormonal, antibody, and chemotherapies in multiple preclinical models. Currently, several phase 3 clinical trials in various cancer types are under way to establish the efficacy of antiangiogenic therapy with a recombinant humanized anti-VEGF monoclonal antibody, bevacizumab (Avastin, rhuMAb-VEGF; Genentech, South San Francisco, CA), in combination with chemotherapeutic agents. PMID:12516032

  10. Imaging chorioretinal vascular disease

    Microsoft Academic Search

    P A Keane; S R Sadda

    2010-01-01

    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

  11. Synthetic vascular prostheses.

    PubMed

    Struszczyk, Marcin H; Bednarek, Pawe?; Raczy?ski, Krzysztof

    2002-01-01

    Polyethyleneterephthalate (PET), and to a lesser extent Teflon have become the major synthetic grafting material. Unlike nylon, Ivalon, and Vinyon-N which lose their tensile strength after implantation, PET and Teflon remain essentially unchanged even after long periods. TRICOMED S.A. produces the family of the knitted vascular implants Dallon made from PET fibres including: Dallon, Dallon H, Tricogel. Both Dallon and Dallon H are manufactured in a form of double (external and internal) velour surface using multifilament yarn and having optimal graft design (a variety of sizes and lengths). The velour surface gives the surface a velvety, plush texture, which improves tissue in--growth. Moreover, Dallon H is a unique vascular prostheses showing the increase in the blood susceptibility that is useful for 4 times less blood demand during preclotting as compared with standard prosthesis. Tricogel graft is made of thin-wall prostheses sealed with the porcine gelatin that provides intraoperative tightness (without preclotting) and the optimal healing process. Hydrophilic behavior of the graft is observed as an instant moistening of the surface with patient's blood and as sweating. The blood stream does not dissolve nor washes away the gelatin but causes the gelatin film to swell, which makes a better tightness. The work will describe the properties of manmade vascular grafts as well as their applications in the vascular surgery. PMID:12391780

  12. Vascular pathology and osteoarthritis

    Microsoft Academic Search

    D. M. Findlay

    2007-01-01

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

  13. Retina vascular network recognition

    Microsoft Academic Search

    Guido Tascini; Giorgio Passerini; Paolo Puliti; Primo Zingaretti

    1993-01-01

    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

  14. Pathogenesis of Vascular Anomalies

    PubMed Central

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

    2010-01-01

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

  15. Amputation in vascular disease.

    PubMed Central

    Robinson, K.

    1980-01-01

    The management of vascular amputees in the Roehampton Limb Surgery Unit since its opening in 1975 is outlined and the results in 167 cases presented. Of the 35 patients over the age of 80, 57% were walking independently at the time of their discharge from the unit. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:7377693

  16. Methylene blue increases systemic vascular resistance in human septic shock

    Microsoft Academic Search

    F. Schneider; Ph. Lutun; M. Hasselmann; J. C. Stoclet; J. D. Tempé

    1992-01-01

    We report the hemodynamic improvements induced by intravenous methylene blue (MB), a guanylate cyclase inhibitor, in 2 patients with hyperdynamic septic shock treated with norepinephrine (NE) infusion, mechanical ventilation an hemodialysis. MB injection augmented the low vascular resistance, mean arterial pressure and induced a slight decrease of cardiac index, without any change of heart rate and pulmonary artery wedge pressure.

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

    Microsoft Academic Search

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

    2001-01-01

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

  18. Acute tumor vascular effects following fractionated radiotherapy in human lung cancer: In vivo whole tumor assessment using volumetric perfusion computed tomography

    SciTech Connect

    Ng, Q.-S. [Marie Curie Research Wing, Mount Vernon Hospital, Northwood (United Kingdom); Goh, Vicky [Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood (United Kingdom); Milner, Jessica [Marie Curie Research Wing, Mount Vernon Hospital, Northwood (United Kingdom); Padhani, Anwar R. [Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood (United Kingdom); Saunders, Michele I. [Marie Curie Research Wing, Mount Vernon Hospital, Northwood (United Kingdom); Hoskin, Peter J. [Marie Curie Research Wing, Mount Vernon Hospital, Northwood (United Kingdom)]. E-mail: peterhoskin@nhs.net

    2007-02-01

    Purpose: To quantitatively assess the in vivo acute vascular effects of fractionated radiotherapy for human non-small-cell lung cancer using volumetric perfusion computed tomography (CT). Methods and Materials: Sixteen patients with advanced non-small-cell lung cancer, undergoing palliative radiotherapy delivering 27 Gy in 6 fractions over 3 weeks, were scanned before treatment, and after the second (9 Gy), fourth (18 Gy), and sixth (27 Gy) radiation fraction. Using 16-detector CT, multiple sequential volumetric acquisitions were acquired after intravenous contrast agent injection. Measurements of vascular blood volume and permeability for the whole tumor volume were obtained. Vascular changes at the tumor periphery and center were also measured. Results: At baseline, lung tumor vascularity was spatially heterogeneous with the tumor rim showing a higher vascular blood volume and permeability than the center. After the second, fourth, and sixth fractions of radiotherapy, vascular blood volume increased by 31.6% (paired t test, p = 0.10), 49.3% (p = 0.034), and 44.6% (p = 0.0012) respectively at the tumor rim, and 16.4% (p = 0.29), 19.9% (p = 0.029), and 4.0% (p = 0.0050) respectively at the center of the tumor. After the second, fourth, and sixth fractions of radiotherapy, vessel permeability increased by 18.4% (p = 0.022), 44.8% (p = 0.0048), and 20.5% (p = 0.25) at the tumor rim. The increase in permeability at the tumor center was not significant after radiotherapy. Conclusion: Fractionated radiotherapy increases tumor vascular blood volume and permeability in human non-small-cell lung cancer. We have established the spatial distribution of vascular changes after radiotherapy; greater vascular changes were demonstrated at the tumor rim compared with the center.

  19. The vascular secret of Klotho.

    PubMed

    Lewin, Ewa; Olgaard, Klaus

    2015-06-01

    Klotho is an evolutionarily highly conserved protein related to longevity. Increasing evidence of a vascular protecting effect of the Klotho protein has emerged and might be important for future treatments of uremic vascular calcification. It is still disputed whether Klotho is locally expressed in the vasculature or whether its vascular effects arise uniquely from its presence in the circulation. PMID:26024025

  20. Engineering vascularized skeletal muscle tissue

    Microsoft Academic Search

    Jeroen Rouwkema; Mara Macdonald; Evan S Garfein; Daniel S Kohane; Diane C Darland; Robert Marini; Clemens A van Blitterswijk; Richard C Mulligan; Patricia A D'Amore; Shulamit Levenberg; Robert Langer

    2005-01-01

    One of the major obstacles in engineering thick, complex tissues such as muscle is the need to vascularize the tissue in vitro. Vascularization in vitro could maintain cell viability during tissue growth, induce structural organization and promote vascularization upon implantation. Here we describe the induction of endothelial vessel networks in engineered skeletal muscle tissue constructs using a three-dimensional multiculture system

  1. Vascular Anomalies and Airway Concerns

    PubMed Central

    Clarke, Caroline; Lee, Edward I.; Edmonds, Joseph

    2014-01-01

    Vascular anomalies, both tumors and malformations, can occur anywhere in the body, including the airway, often without any external manifestations. However, vascular anomalies involving the airway deserve special consideration as proper recognition and management can be lifesaving. In this article, the authors discuss vascular anomalies as they pertains to the airway, focusing on proper diagnosis, diagnostic modalities, and therapeutic options. PMID:25045336

  2. The Vascular Depression Hypothesis: Mechanisms Linking Vascular Disease with Depression

    PubMed Central

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

    2013-01-01

    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

  3. Nanofabrication of negative refractive index metasurfaces

    Microsoft Academic Search

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

    2006-01-01

    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

  4. ALDOSTERONE DYSREGULATION WITH AGING PREDICTS RENAL-VASCULAR FUNCTION AND CARDIO-VASCULAR RISK

    PubMed Central

    Brown, Jenifer M.; Underwood, Patricia C.; Ferri, Claudio; Hopkins, Paul N.; Williams, Gordon H.; Adler, Gail K.; Vaidya, Anand

    2014-01-01

    Aging and abnormal aldosterone regulation are both associated with vascular disease. We hypothesized that aldosterone dysregulation influences the age-related risk of renal- and cardio-vascular disease. We conducted an analysis of 562 subjects who underwent detailed investigations under conditions of liberal and restricted dietary sodium intake (1,124 visits) in a Clinical Research Center. Aldosterone regulation was characterized by the ratio of maximal suppression-to-stimulation (supine serum aldosterone on a liberal sodium diet divided by the same measure on a restricted sodium diet). We previously demonstrated that higher levels of this Sodium-modulated Aldosterone Suppression-Stimulation Index (SASSI) indicate greater aldosterone dysregulation. Renal plasma flow (RPF) was determined via p-aminohippurate clearance to assess basal renal hemodynamics, and the renal-vascular responses to dietary sodium manipulation and angiotensin II (AngII) infusion. Cardiovascular risk was calculated using the Framingham Risk Score. In univariate linear regression, older age (?= -4.60, p<0.0001) and higher SASSI (?= -58.63, p=0.001) predicted lower RPF and a blunted RPF response to sodium loading and AngII infusion. We observed a continuous, independent, multivariate-adjusted interaction between age and SASSI, where the inverse relationship between SASSI and RPF was most apparent with older age (p<0.05). Higher SASSI and lower RPF independently predicted higher Framingham Risk Score (p<0.0001) and together displayed an additive effect. Aldosterone regulation and age may interact to mediate renal-vascular disease. Our findings suggest that the combination of aldosterone dysregulation and renal-vascular dysfunction could additively increase the risk of future cardiovascular outcomes; therefore, aldosterone dysregulation may represent a modifiable mechanism of age-related vascular disease. PMID:24664291

  5. Noncontact monitoring of vascular lesion phototherapy efficiency by RGB multispectral imaging

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  6. Noncontact monitoring of vascular lesion phototherapy efficiency by RGB multispectral imaging.

    PubMed

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

    2013-12-01

    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. PMID:24362928

  7. Plumbing Accretionary Prisms: Effects of Permeability Variations

    NASA Astrophysics Data System (ADS)

    Moore, J. Casey; Brown, Kevin M.; Horath, Frank; Cochrane, Guy; Mackay, Mary; Moore, Greg

    1991-05-01

    Fault zones focus fluid expulsion in the muddy northern Barbados Ridge accretionary prism with fault-parallel permeabilities about 1000 times greater than intergranular permeabilities in the adjacent sediment. In the Oregon prism the low bedding-perpendicular permeability (due to mudstones) inhibits intergranular dewatering; however, intergranular flow is concentrated where submarine erosion breaches high permeability sandy layers. Even so, faults can capture fluid flow from these exposed sandy layers suggesting the faults have a still higher permeability. Such observations coupled with laboratory measurements permeabilities suggest that faults off Oregon may have fault-parallel permeabilities at least 10-10000 times greater than the adjacent sediments. Results from Barbados and Oregon suggest fluid flow is concentrated along the most active faults. At the toe of prisms the fault zones are being progressively loaded by the thickening wedge and are undergoing compaction. Preliminary experiments show that permeability decreases relative to the surrounding wall rocks along faults within this compactive deformation regime; we believe that these faults must undergo dilation, perhaps linked to transient increases in pore pressure if they are to be preferential fluid conduits. Farther upslope erosion exposes rocks that are more consolidated, commonly more cemented, and generally of lower intergranular permeability than rocks of equivalent burial further seaward. Because of their lithification and overconsolidation these rocks dilate during faulting, locally enhancing fracture permeability. In such dilative regimes, faults become evermore focused zones of fluid expulsion relative to occluded intergranular pathways.

  8. Relating Permeability to Diagenesis via Numerical Experimentation

    NASA Astrophysics Data System (ADS)

    Kameda, A.; Bosl, W.; Dvorkin, J.

    2002-12-01

    We quantitatively link permeability to diagenesis in sandstone by conducting numerical pore-scale fluid-flow experiments on a CT-scanned sample. The 3D micro-topology of the sample is represented by zeros for the pores and ones for the mineral phase. Absolute permeability is obtained from lattice-Boltzmann viscous flow simulation in the digital pore space. The numerical results closely match measured permeability in the sample. We numerically alter the original digital sample by (a) depositing cement on the grain surface and (b) inserting small "silt" particles into the pore space. By calculating the permeability of the altered sandstone, we obtain permeability-porosity trends that differ depending on the diagenetic alteration process. Thin-section 2D images of rock are much cheaper to obtain and more readily available than 3D images. Thus we explore the possibility of obtaining accurate permeability estimates from 2D images. In this approach, the 3D digital pore space realizations are generated from digitized 2D images via statistical indicator simulation. We produce digital 2D images from the original 3D digital sample by slicing it in the computer. The 2D porosity of the slices, on average, is the same as the measured 3D porosity. However, the statistical spread around the average value is noticeable. It is remarkable that the calculated permeability of the statistically reconstructed 3D realizations matches, on average, the calculated permeability of the original digital sample and also the measured permeability. Finally, we apply diagenetic alterations to 2D slices, statistically reconstruct the corresponding 3D samples, and calculate their permeability. The results indicate that in clastic sediments, absolute permeability can be accurately estimated from 2D sections. Also, the effect of diagenesis on porosity and permeability can be quantified using 2D section alteration and realistic permeability-porosity trends can be established.

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

    E-print Network

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

  10. [Vascular variability syndromes].

    PubMed

    Otsuka, Kuniaki; Okajima, Kiyotaka; Yamanaka, Takashi; Cornelissen, Germaine

    2014-08-01

    Analytical global and local methods applied to human blood pressure (BP) records of around-the-clock measurements. The chronobiological interpretation of ambulatory BP monitoring records in the light of time-specified reference values derived from healthy peers matched by sex and age identify vascular variability disorders (VVDs) for an assessment of cardio-, cerebro-, and renovascular disease risk. VVD includes circadian BP over-swinging (CHAT, short for circadian hyper-amplitude tension), deficient heart rate variability, MESOR (midline-estimating statistic of rhythm) hypertension, excessively elevated pulse pressure over 60 mmHg, BP ecphasia (an odd timing of the circadian rhythms in BP but not in that of heart rate) and frequency alteration. The term MESOR-hypertension indicates only one of several VVDs that can combine to for sets of 2, 3 and n-component vascular variability syndromes. PMID:25167758

  11. Dynamic permeability of the lacunar-canalicular system in human cortical bone.

    PubMed

    Benalla, M; Palacio-Mancheno, P E; Fritton, S P; Cardoso, L; Cowin, S C

    2014-08-01

    A new method for the experimental determination of the permeability of a small sample of a fluid-saturated hierarchically structured porous material is described and applied to the determination of the lacunar-canalicular permeability [Formula: see text] in bone. The interest in the permeability of the lacunar-canalicular pore system (LCS) is due to the fact that the LCS is considered to be the site of bone mechanotransduction due to the loading-driven fluid flow over cellular structures. The permeability of this space has been estimated to be anywhere from [Formula: see text] to [Formula: see text]. However, the vascular pore system and LCS are intertwined, rendering the permeability of the much smaller-dimensioned LCS challenging to measure. In this study, we report a combined experimental and analytical approach that allowed the accurate determination of the [Formula: see text] to be on the order of [Formula: see text] for human osteonal bone. It was found that the [Formula: see text] has a linear dependence on loading frequency, decreasing at a rate of [Formula: see text]/Hz from 1 to 100 Hz, and using the proposed model, the porosity alone was able to explain 86 % of the [Formula: see text] variability. PMID:24146291

  12. Management of Vascular Malformations

    PubMed Central

    Houbara, Seiji; Hirano, Akiyoshi

    2014-01-01

    Background: Even though vascular malformations are well categorized, further details are relatively unknown. Of treated patients regarding the frequency, demographic distributions, and other related factors by multivariate regression analyses in proportion to total vascular malformations, methods of treatment and how to manage them have not been elucidated thoroughly. Methods: From January 2006 to March 2012, consecutively treated patients with vascular anomalies were included in this investigation at least 1-year follow-up. Results: Of the total of 123 cases, 86 females and 37 males, the mean follow-up was 3.5?±?1.68 years, and the frequency of treatment was 1–8 times (1.8?±?1.30). Surgery was performed for 22 cases (17.9%) of venous malformations and arteriovenous malformations. In multivariate regression, the frequency of treatment was significantly correlated with the length of follow-up (P < 0.001), age (P < 0.05), and type of malformations (P < 0.05) (R2 = 0.18). Need for surgery was significantly increased with age at odds ratio (OR) of 1.06 [95% confidence interval (CI), 1.03–1.80] (P < 0.001), and head/face/neck, and upper limb are more performed at OR of 0.24 (95% CI, 0.07–0.85) (P < 0.05). The satisfaction score varied from 1 to 5 (3.9?±?0.68). Complications occurred in 3 cases (2.4%). In logistic regression of complications, the OR of the satisfaction score was 0.13 (95% CI, 0.02–0.80) (P < 0.05). Conclusions: Treatment of vascular malformations is an integral part of multidisciplinary approaches. Venous malformations are more frequent in combination surgery, and if there are fewer complications, the patients’ satisfaction increases. PMID:25289321

  13. Performance of recycled aggregate concrete monitored by durability indexes

    Microsoft Academic Search

    F. T Olorunsogo; N Padayachee

    2002-01-01

    The report of an investigation into the performance of concrete manufactured with recycled aggregate (RA) using durability indexes as indicators is presented in this paper. Durability indexes, such as chloride conductivity, oxygen permeability and water sorptivity, of three different concrete mixes containing 0%, 50% and 100% RA were monitored at ages 3, 7, 28 and 56 days. The results show

  14. ROCK2 primes the endothelium for vascular hyperpermeability responses by raising baseline junctional tension.

    PubMed

    Beckers, Cora M L; Knezevic, Nebojsa; Valent, Erik T; Tauseef, Mohammad; Krishnan, Ramaswamy; Rajendran, Kavitha; Hardin, C Corey; Aman, Jurjan; van Bezu, Jan; Sweetnam, Paul; van Hinsbergh, Victor W M; Mehta, Dolly; van Nieuw Amerongen, Geerten P

    2015-07-01

    Rho kinase mediates the effects of inflammatory permeability factors by increasing actomyosin-generated traction forces on endothelial adherens junctions, resulting in disassembly of intercellular junctions and increased vascular leakage. In vitro, this is accompanied by the Rho kinase-driven formation of prominent radial F-actin fibers, but the in vivo relevance of those F-actin fibers has been debated, suggesting other Rho kinase-mediated events to occur in vascular leak. Here, we delineated the contributions of the highly homologous isoforms of Rho kinase (ROCK1 and ROCK2) to vascular hyperpermeability responses. We show that ROCK2, rather than ROCK1 is the critical Rho kinase for regulation of thrombin receptor-mediated vascular permeability. Novel traction force mapping in endothelial monolayers, however, shows that ROCK2 is not required for the thrombin-induced force enhancements. Rather, ROCK2 is pivotal to baseline junctional tension as a novel mechanism by which Rho kinase primes the endothelium for hyperpermeability responses, independent from subsequent ROCK1-mediated contractile stress-fiber formation during the late phase of the permeability response. PMID:25869521

  15. Phosphodiesterase 4 inhibition attenuates atrial natriuretic peptide-induced vascular hyperpermeability and loss of plasma volume.

    PubMed

    Lin, Yueh-Chen; Samardzic, Haris; Adamson, Roger H; Renkin, Eugene M; Clark, Joyce F; Reed, Rolf K; Curry, Fitz-Roy E

    2011-01-15

    Inhibition of phosphodiesterase 4 (PDE4) to increase endothelial cAMP and stabilize the endothelial barrier attenuates acute inflammatory increases in vascular permeability.We extended this approach to attenuate physiological increases in vascular permeability in response to atrial natriuretic peptide (ANP), which acts with the kidney to regulate plasma volume. We measured blood-to-tissue albumin clearance and changes in plasma volume in isoflurane-anaesthetized mice (C57BL/6J) pre-treated with rolipram (8 mg kg(-1) I.P., 30 min). Rolipram significantly reduced albumin permeability, measured using a dual-label fluorescence method, in skin and skeletal muscle compared with ANP alone (500 ng kg(-1) min(-1)). Skin and muscle tissue accounted for 70% of the reduction in whole body albumin clearance taking into account albumin clearance in gastrointestinal (GI) tissue, heart and kidney. The action of ANP and rolipram to modify albumin clearances in duodenum and jejunum could be accounted for by local increases in vascular perfusion to increase surface area for exchange. ANP increased haematocrit from 40.6% to 46.8%, corresponding to an average loss of 22% plasma fluid volume (227 ?l), and this was almost completely reversed with rolipram. Renal water excretion accounted for less than 30% of plasma fluid loss indicating that reduced albumin permeability and reduced filtration into vasodilated GI tissue were the predominant actions of PDE4 inhibition. Similar fluid retention was measured in mice with endothelial-restricted deletion of the guanylyl cyclase-A receptor for ANP. Stabilizing the endothelial barrier to offset ANP-induced increases in vascular permeability may be part of a strategy to maintain plasma volume. PMID:21098005

  16. Vascular Endothelial growth factor signaling in hypoxia and Inflammation

    PubMed Central

    Ramakrishnan, S.; Anand, Vidhu; Roy, Sabita

    2014-01-01

    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

  17. Vascular Cambium Development

    PubMed Central

    Nieminen, Kaisa; Blomster, Tiina; Helariutta, Ykä; Mähönen, Ari Pekka

    2015-01-01

    Secondary phloem and xylem tissues are produced through the activity of vascular cambium, the cylindrical secondary meristem which arises among the primary plant tissues. Most dicotyledonous species undergo secondary development, among them Arabidopsis. Despite its small size and herbaceous nature, Arabidopsis displays prominent secondary growth in several organs, including the root, hypocotyl and shoot. Together with the vast genetic resources and molecular research methods available for it, this has made Arabidopsis a versatile and accessible model organism for studying cambial development and wood formation. In this review, we discuss and compare the development and function of the vascular cambium in the Arabidopsis root, hypocotyl, and shoot. We describe the current understanding of the molecular regulation of vascular cambium and compare it to the function of primary meristems. We conclude with a look at the future prospects of cambium research, including opportunities provided by phenotyping and modelling approaches, complemented by studies of natural variation and comparative genetic studies in perennial and woody plant species. PMID:26078728

  18. Vascular Lumen Formation

    PubMed Central

    Lammert, Eckhard; Axnick, Jennifer

    2012-01-01

    The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cell–cell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved. PMID:22474612

  19. Permeability of a Cell Membrane Junction

    PubMed Central

    Politoff, A. L.; Socolar, S. J.; Loewenstein, W. R.

    1969-01-01

    The ion permeability of the membrane junctions between Chironomus salivary gland cells is strongly depressed by treatments that are generally known to inhibit energy metabolism. These treatments include prolonged cooling at 6°–8°C, and exposure to dinitrophenol, cyanide, oligomycin, and N-ethylmaleimide. Intracellular injection of ATP appears to prevent depression of junctional permeability by dinitrophenol or to reverse it. Ouabain, azide, p-chloromercuriphenylsulfonic acid, reserpine, and acetazolamide fail to depress junctional permeability. Thus the ion permeability of the junctional membranes appears to depend on energy provided by oxidative phosphorylation. Possible energy-linked processes for maintaining junctional permeability are discussed, including processes involving transport of permeability-modifying species such as Ca++. PMID:5778320

  20. Micro- and macrovascular endothelial cells in beta-adrenergic regulation of transendothelial permeability.

    PubMed

    Zink, S; Rösen, P; Lemoine, H

    1995-11-01

    Barrier function of endothelial cells (EC) was modulated using beta-adrenergic agonists, e.g., isoproterenol (ISO) and formoterol (FOR). To get a direct comparison between EC from different vascular sources, we isolated EC from aorta (BAEC) and retina (BREC) of the same calf. For permeability studies, EC were cultured on polycarbonate filters. At confluency, transendothelial exchange of the diffusion marker fluorescein isothiocyanate-dextran was determined. Microvascular retinal EC monolayers are half as permeable as monolayers from macrovascular BAEC. When EC are stimulated with beta-adrenergic receptor (AR) agonists, monolayer permeability decreases, and the amount of intracellular adenosine 3',5'-cyclic monophosphate (cAMP) increases in both cell types. Comparison of the half-maximum concentrations causing change in permeability (pEC50) shows direct coupling between beta-AR and adenylate cyclase. The beta 2-selective agonist FOR stimulates cAMP synthesis in BAEC with a pEC50 value of 9.37 and decreases permeability with a pEC50 value of 9.72. In BREC, the pEC50 values of ISO concerning stimulation of cAMP synthesis and the decrease of permeability are also very similar, 5.32 and 5.34, respectively. BREC are not as sensitive to beta 2-AR agonists as BAEC. The pEC50 value of FOR influence on BREC permeability is 8.77 in comparison with 9.72 for BAEC. These results could be interpreted with different affinities of the beta 2-selective AR agonist in BREC and BAEC. PMID:7491911

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

    PubMed

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

    2013-06-01

    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

  2. Retinal Vascular Changes are a Marker for Cerebral Vascular Diseases.

    PubMed

    Moss, Heather E

    2015-07-01

    The retinal circulation is a potential marker of cerebral vascular disease because it shares origin and drainage with the intracranial circulation and because it can be directly visualized using ophthalmoscopy. Cross-sectional and cohort studies have demonstrated associations between chronic retinal and cerebral vascular disease, acute retinal and cerebral vascular disease, and chronic retinal vascular disease and acute cerebral vascular disease. In particular, certain qualitative features of retinopathy, retinal artery occlusion, and increased retinal vein caliber are associated with concurrent and future cerebrovascular events. These associations persist after accounting for confounding variables known to be disease-causing in both circulations, which supports the potential use of retinal vasculature findings to stratify individuals with regards to cerebral vascular disease risk. PMID:26008809

  3. Predicting skin permeability from complex chemical mixtures.

    PubMed

    Riviere, Jim E; Brooks, James D

    2005-10-15

    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(p) = c + mMF + a sigma alpha2(H) + b sigma beta2(H) + s pi2(H) + rR2 + vV(x) where sigma alpha2(H) is the hydrogen-bond donor acidity, sigma beta2(H) is the hydrogen-bond acceptor basicity, pi2(H) is the dipolarity/polarizability, R2 represents the excess molar refractivity, and V(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(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, R2 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. PMID:16183383

  4. Vascular function and ocular involvement in sarcoidosis.

    PubMed

    Siasos, Gerasimos; Paraskevopoulos, Theodoros; Gialafos, Elias; Rapti, Aggeliki; Oikonomou, Evangelos; Zaromitidou, Marina; Mourouzis, Konstantinos; Siasou, Georgia; Gouliopoulos, Nikolaos; Tsalamandris, Sotiris; Vlasis, Konstantinos; Stefanadis, Christodoulos; Papavassiliou, Athanasios G; Tousoulis, Dimitris

    2015-07-01

    Ocular involvement occurs in sarcoidosis (Sar) patients mainly in the form of uveitis. This study was designed to determine if uveitis in Sar patients is associated with vascular impairment. We enrolled 82 Sar patients and 77, age and sex matched, control subjects (Cl). Sar patients were divided into those with ocular sarcoidosis (OS) and those without ocular sarcoidosis (WOS). Endothelial function was evaluated by flow-mediated dilation (FMD). Pulse wave velocity (PWV) was measured as an index of aortic stiffness and augmentation index (AIx) as a measure of arterial wave reflections. Although there was no significant difference in sex, age and mean arterial pressure, patients with OS compared to WOS patients and Cl subjects had impaired FMD (p<0.001), increased AIx (p=0.02) and increased PWV (p=0.001). Interestingly, impaired FMD in Sar patients was independently, from possible covariates (age, sex, smoking habits, arterial hypertension, dyslipidemia), associated with increased odds of ocular involvement (odds ratio=1.69, p=0.001). More precisely ROC curve analysis revealed that FMD had a significant diagnostic ability for the detection of OS (AUC=0.77, p<0.001) with a sensitivity of 79% and a specificity of 68% for an FMD value below 6.00%. To conclude in the present study we have shown that ocular involvement in Sar patients is associated with impaired endothelial function and increased arterial stiffness. These results strengthen the vascular theory which considers uveitis a consequence of vascular dysfunction in Sar patients and reveals a possible clinical importance of the use of endothelial function tests. PMID:25937082

  5. Estimates of equivalent permeability for non-Newtonian fluid flow in heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    di Federico, V.; Pinelli, M.; Ugarelli, R.

    2009-12-01

    Non-Newtonian fluid flow through porous media is of great interest in petroleum engineering, environmental engineering and hydrogeology. An extensive body of literature exists on this topic; several studies are specifically concerned with evaluation of macroscopic models relating the Darcy velocity of the fluid to the pressure gradient; once a macroscopic nonlinear flow law is available, its coupling with the continuity equation results in a nonlinear second-order PDE, whose solution yields the pressure and specific discharge within the domain. At the field scale, the nonlinear problem is further complicated by intrinsic domain heterogeneity, whose interplay with non-Newtonian effects must be accounted for. In such a nonlinear framework, can the heterogeneous permeability distribution be substituted by a representative value, in analogy to the well-known linear (Darcy) case ? Here, we present a simplified approach to the derivation of an equivalent permeability for flow of a purely viscous power-law fluid with flow behavior index n in a heterogeneous porous domain under uniform flow conditions. A standard form of the flow law generalizing the Darcy’s law to non-Newtonian fluids is adopted, with the permeability coefficient being the only source of randomness. The permeability k is taken to vary as a spatially homogeneous and correlated random field, with a given probability density function f(k). Under the ergodic hypothesis, an equivalent permeability is first derived for two limit 1-D flow geometries: flow parallel to permeability variation (serial-type layers), and flow transversal to permeability variation (parallel-type layers). We then investigate whether the equivalent permeability of a 2-D or 3-D isotropic domain can be obtained by a suitable power averaging of 1-D serial and parallel results, generalizing results valid for Newtonian fluids under Darcy’s law. A comparison with an existing analytical solution (confirmed by numerical simulations in the 2-D case), demonstrates that the exponents of power averaging are functions of the flow behavior index n, in variance with the Newtonian (Darcy) case. A sensitivity analysis of the equivalent permeability expression is then performed, quantifying the influence of flow behavior index, shape of the permeability pdf, and permeability or log-permeability variance. As the latter increases, the equivalent permeability is found to decrease for 1-D serial-type layers, and to be a function of n for 1-D parallel-type layers, 2-D and 3-D cases. The equivalent permeability value is highly sensitive to the value of n for very pseudoplastic fluids with n<0.50, less so for dilatant fluids (n>1, not commonly encountered in field cases). For small n, the values of the exponents of the power averaging differ mostly from those valid in the Darcy case, suggesting strong flow channeling. For Newtonian flow, all our expressions for the equivalent permeability reduce to those derived in the past.

  6. Modelling effective permeability of fracture networks in permeable rock formation by

    E-print Network

    Paris-Sud XI, Université de

    Modelling effective permeability of fracture networks in permeable rock formation by singular in a fractured porous rock are used to investigate its effective permeability. If the far field inflow is uniform underground gallery and a geological rock formation presenting several families of fractures. The results

  7. Congenital Vascular Anomalies.

    PubMed

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

    2004-04-01

    Congenital vascular anomalies are rare. The cardiovascular specialist should nevertheless be aware of the more common types of vascular anomalies and understand the implications for patient treatment and the likelihood of associated morbidity. The presentation of congenital arteriovenous malformations can range from asymptomatic or cosmetic lesions, to those causing ischemia, ulceration, hemorrhage, or high-output congestive heart failure. Treatment of large, symptomatic arteriovenous malformations often requires catheter-directed embolization prior to the attempt at complete surgical excision. Later recurrence, due to collateral recruitment, is frequent. Graded compression stockings and leg elevation are the mainstays of treatment for the predominantly venous congenital vascular anomalies. Most congenital central venous disorders are clinically silent. An exception is the retrocaval ureter. Retroaortic left renal vein, circumaortic venous ring, and absent, left-sided or duplicated inferior vena cava are relevant when aortic or inferior vena cava procedures are planned. The treatment of the venous disorders is directed at prevention or management of symptoms. Persistent sciatic artery, popliteal entrapment syndrome, and aberrant right subclavian artery origin are congenital anomalies that are typically symptomatic at presentation. Because they mimic more common diseases, diagnosis is frequently delayed. Delay can result in significant morbidity for the patient. Failure to make the diagnosis of persistent sciatic artery and popliteal entrapment can result in critical limb ischemia and subsequent amputation. Unrecognized aberrant right subclavian artery origin associated with aneurysmal degeneration can rupture and result in death. The treatment options for large-vessel arterial anomalies are surgical, sometimes in combination with endovascular techniques. PMID:15066242

  8. Akt Isoforms in Vascular Disease

    E-print Network

    Yu, Haixiang; Littlewood, Trevor; Bennett, Martin

    2015-04-28

    of VEGF-induced EC migration, through eNOS phosphorylation-mediated NO release, phos- pholipase C-? (PLC-?) activation and F-actin reorganisation [63]. Importantly, Akt1, the major isoform regulating NO release in ECs, is also critical for vascular... tone [71]. Various stimuli such as vascular endothelial growth factor (VEGF) activate Akt in ECs, resulting in Akt-dependent phosphorylation of endothelial nitric oxide synthase (eNOS) to promote NO release; NO is a critical regulator of vascular tone...

  9. Permeability Calculation in a Fracture Network - 12197

    SciTech Connect

    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

    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)

  10. Real-time estimation of paracellular permeability of cerebral endothelial cells by capacitance sensor array

    PubMed Central

    Hyun Jo, Dong; Lee, Rimi; Hyoung Kim, Jin; Oh Jun, Hyoung; Geol Lee, Tae; Hun Kim, Jeong

    2015-01-01

    Vascular integrity is important in maintaining homeostasis of brain microenvironments. In various brain diseases including Alzheimer’s disease, stroke, and multiple sclerosis, increased paracellular permeability due to breakdown of blood-brain barrier is linked with initiation and progression of pathological conditions. We developed a capacitance sensor array to monitor dielectric responses of cerebral endothelial cell monolayer, which could be utilized to evaluate the integrity of brain microvasculature. Our system measured real-time capacitance values which demonstrated frequency- and time-dependent variations. With the measurement of capacitance at the frequency of 100?Hz, we could differentiate the effects of vascular endothelial growth factor (VEGF), a representative permeability-inducing factor, on endothelial cells and quantitatively analyse the normalized values. Interestingly, we showed differential capacitance values according to the status of endothelial cell monolayer, confluent or sparse, evidencing that the integrity of monolayer was associated with capacitance values. Another notable feature was that we could evaluate the expression of molecules in samples in our system with the reference of real-time capacitance values. We suggest that this dielectric spectroscopy system could be successfully implanted as a novel in vitro assay in the investigation of the roles of paracellular permeability in various brain diseases. PMID:26047027

  11. Real-time estimation of paracellular permeability of cerebral endothelial cells by capacitance sensor array.

    PubMed

    Hyun Jo, Dong; Lee, Rimi; Hyoung Kim, Jin; Oh Jun, Hyoung; Geol Lee, Tae; Hun Kim, Jeong

    2015-01-01

    Vascular integrity is important in maintaining homeostasis of brain microenvironments. In various brain diseases including Alzheimer's disease, stroke, and multiple sclerosis, increased paracellular permeability due to breakdown of blood-brain barrier is linked with initiation and progression of pathological conditions. We developed a capacitance sensor array to monitor dielectric responses of cerebral endothelial cell monolayer, which could be utilized to evaluate the integrity of brain microvasculature. Our system measured real-time capacitance values which demonstrated frequency- and time-dependent variations. With the measurement of capacitance at the frequency of 100?Hz, we could differentiate the effects of vascular endothelial growth factor (VEGF), a representative permeability-inducing factor, on endothelial cells and quantitatively analyse the normalized values. Interestingly, we showed differential capacitance values according to the status of endothelial cell monolayer, confluent or sparse, evidencing that the integrity of monolayer was associated with capacitance values. Another notable feature was that we could evaluate the expression of molecules in samples in our system with the reference of real-time capacitance values. We suggest that this dielectric spectroscopy system could be successfully implanted as a novel in vitro assay in the investigation of the roles of paracellular permeability in various brain diseases. PMID:26047027

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

  13. PERMEABILITY OF BACTERIAL SPORES II.

    PubMed Central

    Gerhardt, Philipp; Black, S. H.

    1961-01-01

    Gerhardt, Philipp (University of Michigan, Ann Arbor) and S. H. Black. Permeability of bacterial spores. II. Molecular variables affecting solute permeation. J. Bacteriol. 82:750–760. 1961.—More than 100 compounds were tested for their uptake by dormant spores of a bacillus. The extent of penetration was found to be dependent on at least three molecular properties: (i) The dissociation of electrolytes usually resulted in high or low uptake predictable from their charge. (ii) Lipid insolubility restricted permeation of small molecules. (iii) The molecular weight of unsubstituted glycol and sugar polymers exponentially limited penetration to eventual exclusion at mol wt above 160,000. The results were plotted as a generalized curve, calculations from which permitted an interpretation that the effective spore surface contains pores varying in diameter from 10 to 200 A. PMID:13897940

  14. Regulation of Water Permeability of Vacuolar Symplast

    Microsoft Academic Search

    G. A. Velikanov; L. P. Belova

    2005-01-01

    Effect of exogenous ABA and an inhibitor of energy metabolism NaN3 on water permeability of the desmotubules and tonoplast as the structural elements of vacuolar symplast ensuring water permeability of this transport system was investigated. The methodological approach based on the use of NMR with magnetic field pulse gradient is described in detail. It was shown that ABA affects water

  15. Radionuclide assessment of pulmonary microvascular permeability

    Microsoft Academic Search

    A. B. Johan Groeneveld

    1997-01-01

    The literature has been reviewed to evaluate the technique and clinical value of radionuclide measurements of microvascular permeability and oedema formation in the lungs. Methodology, modelling and interpretation vary widely among studies. Nevertheless, most studies agree on the fact that the measurement of permeability via pulmonary radioactivity measurements of intravenously injected radiolabelled proteins versus that in the blood pool, the

  16. Towards a characteristic equation for permeability 

    E-print Network

    Siddiqui, Adil Ahmed

    2008-10-10

    permeability relation" (CPR). To this end, we have developed 5 CPR formulations -- 3 of which could be considered modifications of "historical" models and 2 of which are "weighted" power law-exponential models. In this work, we consider permeability to be only...

  17. SOIL-AIR PERMEABILITY METHOD EVALUATION

    EPA Science Inventory

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

  18. Influence of fiber packing structure on permeability

    NASA Technical Reports Server (NTRS)

    Cai, Zhong; Berdichevsky, Alexander L.

    1993-01-01

    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.

  19. Water Permeability of Thin Lipid Membranes

    Microsoft Academic Search

    ALBERT CASS; ALAN FINKELSTEIN

    1967-01-01

    The osmotic permeability coefficient, Pf, and the tagged water permeability coefficient, Pn, were determined for thin (< 100 A) lipid mem- branes formed from ox brain lipids plus DL-a-tocopherol; their value of approxi- mately 1 X 10 -3 era\\/see is within the range reported for plasma membranes. It was established that Pf = Pa. Other reports that Pf > Pn

  20. Radial flow permeability measurement. Part B: Application

    Microsoft Academic Search

    J. R Weitzenböck; R. A Shenoi; P. A Wilson

    1999-01-01

    This paper deals with permeability measurement in the context of Resin Transfer Moulding (RTM). A new approach to two-dimensional radial flow permeability measurement with constant inlet pressure is proposed in part A of this paper. In this second part experimental studies are performed to validate the new approach. The new approach is shown to accurately predict the orientation of the

  1. Vascular Distribution of Nanomaterials

    PubMed Central

    Stapleton, Phoebe A.; Nurkiewicz, Timothy R.

    2014-01-01

    Once considered primarily occupational, novel nanotechnology innovation and application has led to widespread domestic use and intentional biomedical exposures. With these exciting advances, the breadth and depth of toxicological considerations must also be expanded. The vascular system interacts with every tissue in the body, striving to homeostasis. Engineered nanomaterials (ENM) have been reported to distribute in many different organs and tissues. However, these observations have tended to use approaches requiring tissue homogenization and/or gross organ analyses. These techniques, while effective in establishing presence, preclude an exact determination of where ENM are deposited within a tissue. It is necessary to identify this exact distribution and deposition of ENM throughout the cardiovascular system, with respect to vascular hemodynamics and in vivo/ in vitro ENM modifications taken into account if nanotechnology is to achieve its full potential. Distinct levels of the vasculature will first be described as individual compartments. Then the vasculature will be considered as a whole. These unique compartments and biophysical conditions will be discussed in terms of their propensity to favor ENM deposition. Understanding levels of the vasculature will also be discussed. Ultimately, future studies must verify the mechanisms speculated on and presented herein. PMID:24777845

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

    NASA Astrophysics Data System (ADS)

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

    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.

  3. Novel vascular endothelial growth factor blocker improves cellular viability and reduces hypobaric hypoxia-induced vascular leakage and oedema in rat brain.

    PubMed

    Saraswat, Deepika; Nehra, Sarita; Chaudhary, Kamal; Cvs, Siva Prasad

    2015-05-01

    Vascular endothelial growth factor (VEGF) is an important cerebral angiogenic and permeability factor under hypoxia. There is a need to find effective molecules that may ameliorate hypoxia-induced cerebral oedema. In silico identification of novel candidate molecules that block VEGF-A site were identified and validated with a Ramachandran plot. The active site residues of VEGF-A were detected by Pocketfinder, CASTp, and DogSiteScorer. Based on in silico data, three VEGF-A blocker (VAB) candidate molecules (VAB1, VAB2, and VAB3) were checked for improvement in cellular viability and regulation of VEGF levels in N2a cells under hypoxia (0.5% O2 ). Additionally, the best candidate molecule's efficacy was assessed in male Sprague-Dawley rats for its ameliorative effect on cerebral oedema and vascular leakage under hypobaric hypoxia 7260 m. All experimental results were compared with the commercially available VEGF blocker sunitinib. Vascular endothelial growth factor-A blocker 1 was found most effective in increasing cellular viability and maintaining normal VEGF levels under hypoxia (0.5% oxygen) in N2a cells. Vascular endothelial growth factor-A blocker 1 effectively restored VEGF levels, decreased cerebral oedema, and reduced vascular leakage under hypobaric hypoxia when compared to sunitinib-treated rats. Vascular endothelial growth factor-A blocker 1 may be a promising candidate molecule for ameliorating hypobaric hypoxia-induced vasogenic oedema by regulating VEGF levels. PMID:25752672

  4. Permeability anisotropy of layering rock model

    NASA Astrophysics Data System (ADS)

    Irayani, Zaroh; Fauzi, Umar; Latief, Fourier Dzar Eljabbar

    2015-04-01

    Computer models of layering system were generated to analyze the effect of layering to the permeability anisotropy. Six layering models were created using non-spherical grain models. Each model consist of three layers with different thickness ratios. The permeability of the generated models were calculated using Lattice Boltzmann Method. Analysis of the flow properties shows that the permeability in the horizontal direction is greater than in the vertical direction. From the permeability anisotropy analysis, it is shown that in the horizontal direction, the models are generally considered as isotropic. This is confirmed by the anisotropy values, which are close to 1. The permeability anisotropy of the vertical direction to horizontal direction varies in the range of 0.32 - 0.45.

  5. Dynamics of permeable particles in concentrated suspensions

    NASA Astrophysics Data System (ADS)

    Abade, Gustavo C.; Cichocki, Bogdan; Ekiel-Je?ewska, Maria L.; Nägele, Gerhard; Wajnryb, Eligiusz

    2010-02-01

    We calculate short-time diffusion properties of suspensions of porous colloidal particles as a function of their permeability, for the full fluid-phase concentration range. The particles are modeled as spheres of uniform permeability with excluded volume interactions. Using a precise multipole method encoded in the HYDROMULTIPOLE program, results are presented for the hydrodynamic function, H(q) , sedimentation coefficient, and self-diffusion coefficients with a full account of many-body hydrodynamic interactions. While self-diffusion and sedimentation are strongly permeability dependent, the wave-number dependence of the hydrodynamic function can be reduced by appropriate shifting and scaling, to a single master curve, independent of permeability. Generic features of the permeable sphere model are discussed.

  6. Dynamics of permeable particles in concentrated suspensions.

    PubMed

    Abade, Gustavo C; Cichocki, Bogdan; Ekiel-Jezewska, Maria L; Nägele, Gerhard; Wajnryb, Eligiusz

    2010-02-01

    We calculate short-time diffusion properties of suspensions of porous colloidal particles as a function of their permeability, for the full fluid-phase concentration range. The particles are modeled as spheres of uniform permeability with excluded volume interactions. Using a precise multipole method encoded in the HYDROMULTIPOLE program, results are presented for the hydrodynamic function, H(q) , sedimentation coefficient, and self-diffusion coefficients with a full account of many-body hydrodynamic interactions. While self-diffusion and sedimentation are strongly permeability dependent, the wave-number dependence of the hydrodynamic function can be reduced by appropriate shifting and scaling, to a single master curve, independent of permeability. Generic features of the permeable sphere model are discussed. PMID:20365518

  7. Renal and Vascular Mechanisms of Thiazolidinedione-Induced Fluid Retention

    PubMed Central

    Yang, Tianxin; Soodvilai, Sunhapas

    2008-01-01

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

  8. Composites with tuned effective magnetic permeability

    NASA Astrophysics Data System (ADS)

    Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2007-07-01

    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)].

  9. An Immersed Boundary Method for Computing Anisotropic Permeability of

    E-print Network

    Al Hanbali, Ahmad

    = - k µf · pf (k: permeability tensor) k: measure of flAn Immersed Boundary Method for Computing Anisotropic Permeability of Structured Porous Media David for Computing Anisotropic Permeability of Structured Porous Media #12;Outline 1 Averaged transport in porous

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

    PubMed Central

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

    2013-01-01

    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

  11. Interstitial Vascularity in Fibrosing Alveolitis

    Microsoft Academic Search

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

    2003-01-01

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

  12. The Mayo Vascular Center Experience

    Microsoft Academic Search

    J. W Hallett; T. W Rooke; M Koch

    1998-01-01

    American medicine is trending toward an increasing number of specialty care centers. Cancer centers, transplant centers, and sports medicine centers are only a few common examples. Vascular centers are relatively new entities that are forming for obvious reasons. As the general population ages, peripheral vascular disease has become more prevalent. Several types of medical, surgical, and radiological specialists are involved

  13. Mineralocorticoid Receptors Modulate Vascular Endothelial Function in Human Obesity

    PubMed Central

    Hwang, Moon-Hyon; Yoo, Jeung-Ki; Luttrell, Meredith; Kim, Han-Kyul; Meade, Thomas H.; English, Mark; Segal, Mark S.; Christou, Demetra D.

    2015-01-01

    Obesity increases linearly with age and is associated with impaired vascular endothelial function and increased risk for cardiovascular disease. Mineralocorticoid receptors (MR) contribute to impaired vascular endothelial function in cardiovascular disease; however, their role in uncomplicated human obesity is unknown. Because plasma aldosterone levels are elevated in obesity and adipocytes may be a source of aldosterone, we hypothesized that MR modulate vascular endothelial function in older adults in an adiposity-dependent manner. To test this hypothesis, we administered MR blockade (Eplerenone; 100 mg/day) for 1 month in a balanced, randomized, double-blind, placebo-controlled, crossover study to 22 older adults (10 men, 55–79 years) varying widely in adiposity (body mass index: 20–45 kg/m2) but who were free from overt cardiovascular disease. We evaluated vascular endothelial function (brachial artery flow-mediated dilation [FMD] via ultrasonography) and oxidative stress (plasma F2-isoprostanes and vascular endothelial cell protein expression of nitrotyrosine and NADPH oxidase p47phox) during placebo and MR blockade. In the whole group, oxidative stress (P>0.05) and FMD did not change with MR blockade (6.39±0.67 vs. 6.23±0.73 %, P=0.7, placebo vs. Eplerenone). However, individual improvements in FMD in response to Eplerenone were associated with higher total body fat (body mass index: r=0.45, P=0.02 and DXA-derived % body fat: r=0.50, P=0.009) and abdominal fat (total: r=0.61, P=0.005, visceral: r=0.67, P=0.002 and subcutaneous: r=0.48, P=0.03). In addition, greater improvements in FMD with Eplerenone were related with higher baseline fasting glucose (r=0.53, P=0.01). MR influence vascular endothelial function in an adiposity-dependent manner in healthy older adults. PMID:23786536

  14. Selective irradiation of the vascular endothelium

    E-print Network

    Schuller, Bradley W

    2007-01-01

    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 ...

  15. 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.

  16. Ascorbate protects against vascular leakage in cecal ligation and puncture-induced septic peritonitis.

    PubMed

    Zhou, Gang; Kamenos, George; Pendem, Suresh; Wilson, John X; Wu, Feng

    2012-02-15

    Vascular leakage in multiple organs is a characteristic pathological change in sepsis. Our recent study revealed that ascorbate protects endothelial barrier function in microvascular endothelial cell monolayers through inhibiting serine/threonine protein phosphatase 2A (PP2A) activation (Han M, Pendem S, Teh SL, Sukumaran DK, Wu F, Wilson JX. Free Radic Biol Med 48: 128-135, 2010). The present study addressed the mechanism of protection by ascorbate against vascular leakage in cecal ligation and puncture (CLP)-induced septic peritonitis in mice. CLP caused NADPH oxidase activation and endothelial nitric oxide synthase (eNOS) uncoupling to produce superoxide, increased NO production by inducible NOS (iNOS) and neuronal NOS (nNOS) activity, and elevated 3-nitrotyrosine (a product of peroxynitrite) formation and PP2A activity in the hindlimb skeletal muscles at 12 h after CLP. The increase in PP2A activity was associated with decreased levels of phosphorylated serine and threonine in occludin, which was immunoprecipitated from freshly harvested endothelial cells of the septic skeletal muscles. Moreover, CLP increased the vascular permeability to fluorescent dextran and Evans blue dye in skeletal muscles. An intravenous bolus injection of ascorbate (200 mg/kg body wt), given 30 min prior to CLP, prevented eNOS uncoupling, attenuated the increases in iNOS and nNOS activity, decreased 3-nitrotyrosine formation and PP2A activity, preserved the phosphorylation state of occludin, and completely inhibited the vascular leakage of dextran and Evans blue. A delayed ascorbate injection, given 3 h after CLP, also prevented the vascular permeability increase. We conclude that ascorbate injection protects against vascular leakage in sepsis by sequentially inhibiting excessive production of NO and superoxide, formation of peroxynitrite, PP2A activation, and occludin dephosphorylation. Our study provides a scientific basis for injection of ascorbate as an adjunct treatment for vascular leakage in sepsis. PMID:22116513

  17. Angiogenic and astroglial responses to vascular endothelial growth factor administration in adult rat brain

    Microsoft Academic Search

    J. M Krum; N Mani; J. M Rosenstein

    2002-01-01

    The effects of exogenous vascular endothelial growth factor (VEGF) on angiogenesis, blood–brain barrier permeability and astroglial proliferation in the adult rat CNS in situ were investigated. Recombinant human VEGF165 (25 or 50 ng\\/ml) was delivered for up to 1 week using either intracerebral osmotic minipumps or less traumatic subdural gelatin sponge placement. By 3 days, VEGF delivery caused significantly increased

  18. Vascular Development in the Zebrafish

    PubMed Central

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

    2012-01-01

    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

  19. Caffeine's Vascular Mechanisms of Action.

    PubMed

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

    2010-01-01

    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

  20. Caffeine's Vascular Mechanisms of Action

    PubMed Central

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

    2010-01-01

    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

  1. Estimation of pulmonary vascular resistance with Doppler diastolic gradients.

    PubMed

    Atiq, Mehnaz; Tasneem, Habiba; Aziz, Kalimuddin

    2008-06-01

    This study was undertaken to determine the diastolic Doppler echocardiographic correlates of pulmonary vascular resistance calculated on cardiac catheterization in patients with secondary pulmonary arterial hypertension. Thirty-eight consecutive patients with congenital heart disease, pulmonary artery hypertension and pulmonary regurgitation were studied. Continuous-wave Doppler-derived pulmonary artery diastolic gradients were measured at 3 points on the pulmonary regurgitant diastolic velocity slope: peak diastolic, end-diastolic (at the R wave on the electrocardiogram), and mid-diastolic (midway between the peak and end-diastolic points). Catheterization data included oximetry, measurements of pressure in the cardiac chambers and great arteries, and calculation of pulmonary vascular resistance index. Doppler-derived peak, mid, and end-diastolic pulmonary regurgitation gradients correlated best with catheterization-measured pulmonary artery systolic, mean and diastolic pressures, respectively. The best Doppler correlate of pulmonary vascular resistance index was the pulmonary artery end-diastolic gradient. Clinically useful information can be obtained from Doppler pulmonary artery diastolic gradients measured on the pulmonary regurgitant diastolic velocity slope, which can estimate the pulmonary arterial pressure as well as pulmonary vascular resistance obtained on cardiac catheterization. PMID:18515672

  2. A fast nonlinear regression method for estimating permeability in CT perfusion imaging

    PubMed Central

    Bennink, Edwin; Riordan, Alan J; Horsch, Alexander D; Dankbaar, Jan Willem; Velthuis, Birgitta K; de Jong, Hugo W

    2013-01-01

    Blood–brain barrier damage, which can be quantified by measuring vascular permeability, is a potential predictor for hemorrhagic transformation in acute ischemic stroke. Permeability is commonly estimated by applying Patlak analysis to computed tomography (CT) perfusion data, but this method lacks precision. Applying more elaborate kinetic models by means of nonlinear regression (NLR) may improve precision, but is more time consuming and therefore less appropriate in an acute stroke setting. We propose a simplified NLR method that may be faster and still precise enough for clinical use. The aim of this study is to evaluate the reliability of in total 12 variations of Patlak analysis and NLR methods, including the simplified NLR method. Confidence intervals for the permeability estimates were evaluated using simulated CT attenuation–time curves with realistic noise, and clinical data from 20 patients. Although fixating the blood volume improved Patlak analysis, the NLR methods yielded significantly more reliable estimates, but took up to 12 × longer to calculate. The simplified NLR method was ?4 × faster than other NLR methods, while maintaining the same confidence intervals (CIs). In conclusion, the simplified NLR method is a new, reliable way to estimate permeability in stroke, fast enough for clinical application in an acute stroke setting. PMID:23881247

  3. Anisotropy of permeability in faulted porous sandstones

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  4. Permeability Scaling of Kozeny-type Equations

    NASA Astrophysics Data System (ADS)

    Winter, C.; Smolarkiewicz, P.; Hyman, J. D.

    2011-12-01

    The Kozeny equation states that the permeability of a porous medium is proportional to the product of porosity with the square of mean hydraulic radius. A Kozeny-type equation is a more general function of the product of porosity and hydraulic radius that estimates permeability, in this case a power law. Since its introduction in 1927, the Kozeny equation has been widely applied, but with mixed results. We present computational evidence that the Kozeny equation is most accurate when applied to samples of porous media that are not far from a pore percolation limit, i.e., media with a relatively small fraction of pores extending completely through them. Furthermore, we compare estimates of permeabilities from the Kozeny equation to estimates obtained from three Kozeny-type power laws. Comparisons are based on steady-state solutions of the Navier-Stokes equations in explicit pore spaces of both natural and realistic simulated porous media. A form of level set percolation is used to generate the simulated media. Permeability is estimated by calculating the flux of water and the pressure gradient at every point in a given pore space and then averaging. Our results indicate that power law alternatives can accurately estimate permeabilities across a wide range of porous media. Since they depend on porosity and hydraulic radius, which can be measured in bulk, they may extend to continuum representations of permeability. We augment estimates of permeability with approximate 95% confidence intervals for model estimates.

  5. Permeability evolution during densification of magma

    NASA Astrophysics Data System (ADS)

    Wadsworth, Fabian B.; Scheu, Bettina; Heap, Michael; Schipper, C. Ian; Vasseur, Jeremie; Kennedy, Ben; von Aulock, Felix W.; Lavallee, Yan; Kendrick, Jackie E.; Dingwell, Donald B.

    2015-04-01

    Constraint of the gas permeability of magmas is of key importance to estimating outgassing timescales and the evolution of pore-space overpressure. Once magma develops a permeable pore phase over a sufficient lengthscale, densification will ensue. Densification can be driven by surface tension during the minimisation of internal surface area, by gravitational compaction or by anisotropic shear strain. In all cases, the evolution of permeability is not well constrained. We provide a suite of experiments using both natural and synthetic magmas with a wide range of initial pore volume fractions and geometries. In the first subset of experiments we bathe the magma in argon and measure the temporal evolution of the porosity during surface-tension driven densification. In the second subset, we apply an additional uniaxial load to the magma. In both scenarios we measure the gas permeability before and after experimentation. We find that there are unique trajectories of the porosity permeability relationship depending on the densification mechanism. This demonstrates the paucity of simple models for the description of porosity permeability relationships in magmas. We propose that densification should happen rapidly in volcanic conduits between eruptions and that permeable outgassing scenarios may be complicated by this process.

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

    PubMed Central

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

    2014-01-01

    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

  7. UK Index

    NSDL National Science Digital Library

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

  8. Endothelial cell permeability during hantavirus infection involves factor XII-dependent increased activation of the kallikrein-kinin system.

    PubMed

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

    2013-01-01

    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

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

    PubMed Central

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

    2013-01-01

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

  10. Gas Permeable Chemochromic Compositions for Hydrogen Sensing

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

  11. Gluteal Compartment Syndrome following Vascular and Neurological Injuries

    PubMed Central

    Hafez, Mahmoud A.; Radwan, Moustafa

    2014-01-01

    Gluteal compartment syndrome is a serious but rare condition that has recently been increasingly reported in literature. This report presents two cases that followed neurological and vascular injuries (first case: an injury of the superior gluteal artery; second case: neurological injury bilaterally). A high index of suspicion and attention is needed to early diagnose this condition due to the possibility of developing serious and potentially fatal complications and difficulty in management. PMID:24711822

  12. Vascular Endothelial Growth Factor in Eye Disease

    PubMed Central

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

    2012-01-01

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

  13. Nitric Oxide Increases Arterial Endotheial Permeability through Mediating VE-Cadherin Expression during Arteriogenesis

    PubMed Central

    Wu, Xiaoqiong; Guan, Yinglu; Zhang, Bin; Cai, Weijun; Schaper, Jutta; Schaper, Wolfgang

    2015-01-01

    Macrophage invasion is an important event during arteriogenesis, but the underlying mechanism is still only partially understood. The present study tested the hypothesis that nitric oxide (NO) and VE-cadherin, two key mediators for vascular permeability, contribute to this event in a rat ischemic hindlimb model. In addition, the effect of NO on expression of VE-caherin and endothelial permeability was also studied in cultured HUVECs. We found that: 1) in normal arteriolar vessels (NAV), eNOS was moderately expressed in endothelial cells (EC) and iNOS was rarely detected. In contrast, in collateral vessels (CVs) induced by simple femoral artery ligation, both eNOS and iNOS were significantly upregulated (P<0.05). Induced iNOS was found mainly in smooth muscle cells, but also in other vascular cells and macrophages; 2) in NAV VE-cadherin was strongly expressed in EC. In CVs, VE-cadherin was significantly downregulated, with a discontinuous and punctate pattern. Administration of nitric oxide donor DETA NONOate (NONOate) further reduced the amounts of Ve-cadherin in CVs, whereas NO synthase inhibitor L-NAME inhibited downregulation of VE-cadherin in CVs; 3) in normal rats Evans blue extravasation (EBE) was low in the musculus gracilis, FITC-dextron leakage was not detected in the vascular wall and few macrophages were observed in perivascular space. In contrast, EBE was significantly increased in femoral artery ligation rats, FITC-dextron leakage and increased amounts of macrophages were detected in CVs, which were further enhanced by administration of NONOate, but inhibited by L-NAME supplement; 4) in vitro experiments confirmed that an increase in NO production reduced VE-cadherin expression, correlated with increases in the permeability of HUVECs. In conclusion, our data for the first time reveal the expression profile of VE-cadherin and alterations of vascular permeability in CVs, suggesting that NO-mediated VE-cadherin pathway may be one important mechanism responsible, at least in part, for macrophage invasion during arteriogenesis. PMID:26133549

  14. Vascular Injuries: Trends in Management

    PubMed Central

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

    2012-01-01

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

  15. Piezo1 integration of vascular architecture with physiological force

    PubMed Central

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

    2014-01-01

    The mechanisms by which physical forces regulate endothelial cells to determine the complexities of vascular structure and function are enigmatic1-5. Studies of sensory neurons have suggested Piezo proteins as subunits of Ca2+-permeable non-selective cationic channels for detection of noxious mechanical impact6-8. Here we show Piezo1 (FAM38A) channels as sensors of frictional force (shear stress) and determinants of vascular structure in both development and adult physiology. Global or endothelial-specific disruption of mouse Piezo1 profoundly disturbed the developing vasculature and was embryonic lethal within days of the heart beating. Haploinsufficiency was not lethal but endothelial abnormality was detected in mature vessels. Importance of Piezo1 channels as sensors of blood flow was shown by Piezo1 dependence of shear stress-evoked ionic current and calcium influx in endothelial cells and the ability of exogenous Piezo1 to confer sensitivity to shear stress on otherwise resistant cells. Downstream of this calcium influx was protease activity and spatial organization of endothelial cells to the polarity of the applied force. The data suggest Piezo1 channels as pivotal integrators in vascular biology. PMID:25119035

  16. NADPH Oxidases in Vascular Pathology

    PubMed Central

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

    2014-01-01

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

  17. Infrared magnetic and negative-index metamaterials

    NASA Astrophysics Data System (ADS)

    Zhang, Shuang

    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.

  18. 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...

  19. 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...

  20. 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...

  1. Tailoring wall permeabilities for enhanced filtration

    NASA Astrophysics Data System (ADS)

    Herterich, J. G.; Vella, D.; Field, R. W.; Hankins, N. P.; Griffiths, I. M.

    2015-05-01

    The build-up of contaminants at the wall of cross-flow membrane filtration systems can be detrimental to the operation of such systems because of, amongst other things, the osmotic backflow it may induce. In this paper, we propose a strategy to avoid the negative effects of backflow due to osmosis by using 2D channels bounded by walls with a combination of permeable and impermeable segments. We show that preventing flow through the final portion of the channel can increase the efficiency of filtration and we determine the optimal fraction occupied by the permeable wall that maximizes efficiency. Our analysis uses a combination of numerical techniques and asymptotic analysis in the limit of low wall permeabilities. Finally, we consider how the energy cost of filtration depends on the Péclet number and show that the energy cost per unit of filtered water may be minimized by appropriately choosing both the Péclet number and the permeable-region fraction.

  2. Electrochemical permeability of GCO: Estimation of overpotentials

    Microsoft Academic Search

    F. M. Figueiredo; F. M. B. Marques; J. R. Frade

    1999-01-01

    The basic relationships required to analyse permeability data of fluorite-based solid electrolytes are rewritten in order\\u000a to account for an overpotential term related to slow surface exchange. Results of a gadolinia doped ceria solid electrolyte\\u000a suggest that surface exchange might limit the permeability especially at low Po2 and temperature. However, the analysis of the data with different relationships leads to

  3. A New Magnetic Material of High Permeability

    Microsoft Academic Search

    O. L. Boothby; R. M. Bozorth

    1947-01-01

    This paper describes the preparation, heat treatment, and properties of supermalloy, a magnetic alloy of iron, nickel, and molybdenum. In the form of 0.014 in. sheet it has an initial permeability of 50,000 to 150,000, a maximum permeability of 600,000 to 1,200,000, coercive force of 0.002 to 0.005 oersted, and a hysteresis loss of less than 5 ergs?cm3?cycle at B=5000.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

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

    PubMed Central

    1983-01-01

    The reflection coefficient (sigma) and permeability (P) of urea and ethylene glycol were determined by fitting the equations of Kedem and Katchalsky (1958) to the change in light scattering produced by adding a permeable solute to a red cell suspension. The measurements incorporated three important modifications: (a) the injection artifact was eliminated by using echinocyte cells; (b) the use of an additional adjustable parameter (Km), the effective dissociation constant at the inner side of the membrane; (c) the light scattering is not directly proportional to cell volume (as is usually assumed) because refractive index and scattering properties of the cell depend on the intracellular permeable solute concentration. This necessitates calibrating for known changes in refractive index (by the addition of dextran) and cell volume (by varying the NaCl concentration). The best fit was for sigma = 0.95, Po = 8.3 X 10(-4) cm/s, and Km = 100 mM for urea and sigma = 1.0, Po = 3.9 X 10(-4) cm/s, and Km = 30 mM for ethylene glycol. The effects of the inhibitors copper, phloretin, p- chloromercuriphenylsulfonate, and 5,5'-dithiobis (2-nitro) benzoic acid on the urea, ethylene glycol, and water permeability were determined. The results suggest that there are three separate, independent transport systems: one for water, one for urea and related compounds, and one for ethylene glycol and glycerol. PMID:6842174

  6. Permeability response of the rat mesenteric microvasculature to insulin

    PubMed Central

    Sasaki, Rie; Whitt, Stevan P.; Huxley, Virginia H.

    2012-01-01

    Whether insulin influences microvascular exchange is important in understanding its specific role in insulin resistance and the treatment of diabetes. We investigated whether insulin could induce changes in the microvascular flux of albumin from the mesenteric venules of anesthetized male and female Sprague-Dawley rats (n = 11). After catheterization for monitoring of mean arterial pressure (MAP), a loop of small intestine was exteriorized. The mesentery was draped over a coverslip for observation and suffused continuously with bicarbonate-buffered solution (BBS) (pH 7.4, 37°C). After intravenous injection of Alexa 594™ labeled bovine serum albumin (BSA, 8 mg/kg), fluorescence intensity (If) was recorded on videotape for 30 minutes BBS suffusion and 75 minutes suffusion of BBS plus 0.02 U/ml porcine insulin. Microvascular flux of BSA was measured as a leak index (LI) of If in a 10 × 30 ?m window over a postcapillary venule relative to If of the adjoining tissue. Insulin induced a rapid 34% decrease in LI within 5 minutes (p < 0.05) that was sustained for the next 30 minutes. We also observed gender and age differences in the permeability response to insulin, as there was a sustained ?59% decrease in LI in adult females (n = 5) after 25 minutes, whereas there was an acute, transient (15 min) 45% decrease in LI in juvenile males (n = 6). We conclude that insulin reduces mesenteric venule permeability differently in males and females. Further studies are needed to differentiate the permeability responses with respect to age and gender. PMID:16543645

  7. Epithelial permeability reflects subclinical effects of contact lens wear

    PubMed Central

    McNamara, N.; Fusaro, R.; Brand, R.; Polse, K.

    1998-01-01

    AIMS—Recently, it was reported by the authors that a single drop fluorophotometric technique for estimating corneal epithelial permeability (Pdc) to fluorescein is not sufficiently precise for monitoring permeability changes in individual patients, but may be useful for evaluating mean differences in Pdc in population based research. To determine whether this technique provides a more sensitive index of epithelial integrity compared with conventional clinical assessments, the effects of mild corneal trauma on Pdc, the slit lamp appearance of the cornea, and corneal thickness (CT) were assessed.?METHODS—After baseline slit lamp examinations (SLE) and CT measurements, one randomly chosen eye of each of 32 normal subjects underwent 1 hour of closed eye soft contact lens (CL) wear while the fellow eye served as a control (no CL). After removing the CL, the SLE and CT measurements were repeated. Then, Pdc to fluorescein was assessed using a single drop fluorophotometric method refined to enhance feasibility, precision, and accuracy.?RESULTS—The mean (95% confidence interval) difference in natural log (Pdc) between 32 pairs of eyes (CL minus no CL) was 0.341 (0.069, 0.613), p = 0.016. By contrast, none of the 32 subjects exhibited corneal epithelial disruption upon SLE with white light following the closed eye period. Also, no substantial differences were apparent in the corneal swelling response between paired eyes, mean ?CT (95% CI) = ?2.31(?7.53, 2.91) µm, p=0.37.?CONCLUSIONS—Pdc measurements, used in studies of modest sample size, appear capable of detecting average differences in corneal barrier function that remain undetectable by SLE or pachymetry.?? Keywords: contact lens; corneal epithelium; epithelial permeability; fluorophotometry; pachymetry PMID:9640184

  8. Systemic Vascular Function Is Associated with Muscular Power in Older Adults

    PubMed Central

    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

    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

  9. Simulating Perforation Permeability Damage and Cleanup

    SciTech Connect

    Morris, J.P.; Lomov, I.N.; Glenn, L.A.

    2000-09-01

    Completion of cased and cemented wells by shaped charge perforation causes its own damage to the formation, potentially reducing well productivity. In practice it is found that underbalance conditions clean up the damaged zone to some extent, however, the mechanisms of these processes are poorly understood. Most hydrocodes typically used to simulate rock response to shaped charge penetration do not provide permeability estimates. Furthermore, the time scales for formation clean up are potentially much longer than the period of jet penetration. We have developed a simple, yet accurate model for the evolution of porosity and permeability which can easily be incorporated into existing hydrocodes using information from the history of each cell. In addition, we have developed a code that efficiently simulates fines migration during the post-shot surge period using initial conditions taken directly from hydrocode simulations of jet penetration. Results from a one-dimensional model simulation are in excellent agreement with measured fines and permeability distributions. We also present two-dimensional numerical results which qualitatively reproduce experimentally obtained permeability maps for different values of underbalance. Although initial results have been promising, further comparison with experiment is essential to tune the coupling between the hydrocode and fines migration simulator. Currently the permeability model is most appropriate for high permeability sandstones (such as Berea), but with little effort, the model can be extended to other rock types, given sufficient experimental data.

  10. Simulating perforation permeability damage and cleanup

    SciTech Connect

    Morris, J P; Lomov, I N; Glenn, L A

    2000-12-15

    Completion of cased and cemented wells by shaped charge perforation causes its own damage to the formation, potentially reducing well productivity. In practice it is found that underbalance conditions clean up the damaged zone to some extent, however, the mechanisms of these processes are poorly understood. Most hydrocodes typically used to simulate rock response to shaped charge penetration do not provide permeability estimates. Furthermore, the time scales for formation clean up are potentially much longer than the period of jet penetration. We have developed a simple, yet accurate model for the evolution of porosity and permeability which can easily be incorporated into existing hydrocodes using information from the history of each cell. In addition, we have developed a code that efficiently simulates fines migration during the post-shot surge period using initial conditions taken directly from hydrocode simulations of jet penetration. Results from a one-dimensional model simulation are in excellent agreement with measured permeability distributions. We also present two-dimensional numerical results which qualitatively reproduce experimentally obtained permeability maps for different values of underbalance. Although initial results have been promising, further comparison with experiment is essential to tune the coupling between the hydrocode and fines migration simulator. Currently the permeability model is most appropriate for high permeability sandstones (such as Berea), but with little effort, the model can be extended to other rock types, given sufficient experimental data.

  11. Laser Vascular Welding

    NASA Astrophysics Data System (ADS)

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

    1988-06-01

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

  12. Jung Index

    NSDL National Science Digital Library

    1999-01-01

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

  13. Biomaterials for vascular tissue engineering

    PubMed Central

    Ravi, Swathi; Chaikof, Elliot L

    2010-01-01

    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

  14. Thermal analysis of vascular reactivity

    E-print Network

    Deshpande, Chinmay Vishwas

    2009-05-15

    Cardiovascular disease (CVD) is the leading cause of death in the United States. Analysis of vascular reactivity (VR) in response to brachial artery occlusion is used to estimate arterial health and to determine the likelihood of future...

  15. Kidney Failure and Vascular Disease

    MedlinePLUS

    ... com Cleveland Clinic @ 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, ...

  16. Hormone interactions during vascular development

    Microsoft Academic Search

    Jan Dettmer; Annakaisa Elo; Ykä Helariutta

    2009-01-01

    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.

  17. Infrared Imaging Of Vascular Changes

    NASA Astrophysics Data System (ADS)

    Jones, Colin H.

    1988-10-01

    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.

  18. Vascular tumors simulating occlusive disease.

    PubMed

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

    2001-02-01

    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

  19. Vascular Ehlers–Danlos syndrome

    Microsoft Academic Search

    Dominique P Germain; Yessica Herrera-Guzman

    2004-01-01

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

  20. DPIV Measurements of Vortex Ring Interaction with Multiple Permeable Screens

    NASA Astrophysics Data System (ADS)

    Musta, Mustafa N.; Krueger, Paul S.

    2009-11-01

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

  1. Transformation of the Collateral Vascular Bundles into Amphivasal Vascular Bundles in an Arabidopsis Mutant1

    Microsoft Academic Search

    Ruiqin Zhong; Jennifer J. Taylor; Zheng-Hua Ye

    1999-01-01

    Arabidopsis inflorescence stems develop a vascular pattern sim- ilar to that found in most dicots. The arrangement of vascular tissues within the bundle is collateral, and vascular bundles in the stele are arranged in a ring. Although auxin has been shown to be an inducer of vascular differentiation, little is known about the molecular mechanisms controlling vascular pattern formation. By

  2. Aminoguanidine Effects on Nerve Blood Flow, Vascular Permeability, Electrophysiology, and Oxygen Free Radicals

    Microsoft Academic Search

    Mikihiro Kihara; James D. Schmelzer; Joseph F. Poduslo; Geoffrey L. Curran; Kim K. Nickander; Phillip A. Low

    1991-01-01

    Since advanced glycosylation end products have been suggested to mediate hyperglycemia-induced microvascular atherogenesis and because aminoguanidine (AG) prevents their generation, we 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 (25 mg\\\\cdotkg-1\\\\cdotday-1), group II received STZ plus

  3. Role of Pertussis Toxin A Subunit in Neutrophil Migration and Vascular Permeability

    Microsoft Academic Search

    GERLY A. C. BRITO; MARCELLUS H. L. P. SOUZA; ANTONIO A. MELO-FILHO; ERIK L. HEWLETT; ALDO A. M. LIMA; CARLOS A. FLORES; ANDRONALDO A. RIBEIRO

    1997-01-01

    The anti-inflammatory activity of pertussis toxin (Ptx) was compared to that of a noncatalytic mutant of pertussis toxin (9K\\/129G; Ptxm), which contains two amino acid substitutions in the A protomer, by using a rat model of inflammation. The toxins were administered intravenously 1 h prior to the injection of inflam- matory stimuli. Ptx, but not Ptxm, inhibited neutrophil migration into

  4. Comparison of lung vascular and epithelial permeability indices in the adult respiratory distress syndrome

    SciTech Connect

    Braude, S.; Nolop, K.B.; Hughes, J.M.; Barnes, P.J.; Royston, D.

    1986-06-01

    Measurements of pulmonary clearance of inhaled /sup 99m/Tc-DTPA and transvascular 113mIn-transferrin flux were made in 12 patients with established ARDS and 14 volunteer control subjects (7 smokers and 7 nonsmokers). Smokers had significantly increased /sup 99m/Tc-DTPA clearance (clearance rate constant, 3.6 +/- 0.8; mean +/- SEM) compared with nonsmokers (1.2 +/- 0.1). All patients with ARDS had increased clearance of /sup 99m/Tc-DTPA (5.2 +/- 0.9), but the finding was nonspecific in that increased clearance overlapped with the findings in normal smokers. Protein flux in smokers (protein flux units, 0.0 +/- 0.2) was similar to that in nonsmokers (0.3 +/- 0.2). In 9 of the 12 patients with ARDS, protein flux was increased, and as a group (3.2 +/- 1.0) they differed significantly (p less than 0.01) from the combined smoking and nonsmoking control subjects (0.2 +/- 0.1, n = 14). The parameters of DTPA clearance and transvascular protein flux correlated well in the patients with ARDS (Spearman's rank correlation = 0.71, p less than 0.01). Although /sup 99m/Tc-DTPA clearance is a sensitive technique in ARDS, a single study in this context does not allow a diagnostic conclusion because of its non-specificity. Abnormal protein flux appears to be more specific for ARDS but was not a universal finding in the patients studied.

  5. Comparison of Permeability for non-crimp fabricsComparison of Permeability for non crimp fabrics Jose Pariona-Lrtiga

    E-print Network

    Floreano, Dario

    from 63 mPa.s and 77 mPa.s. This uncertainty influenced also the permeability measurements. Kx Ky (80 °C) Ke (60 °C) ·Despite the difference in the fibre set-up, the fibre permeability measuredComparison of Permeability for non-crimp fabricsComparison of Permeability for non crimp fabrics

  6. 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/

  7. Time course of permeability changes and PMN flux in rat trachea following O3 exposure

    SciTech Connect

    Young, C.; Bhalla, D.K. (Community and Environmental Medicine, University of California, Irvine (United States))

    1992-02-01

    Changes in rat tracheal epithelial permeability and polymorphonuclear leukocyte (PMN) populations during a 24-hr time period following a 3-hr exposure to 0.8 ppm ozone (O3) were investigated. An increase in permeability to 99mTc-diethylene-triaminepentaacetate (DTPA) occurred immediately after the exposure, peaked at the 8-hr time point and decreased to control level by 24 hr. For correlation with tracheal permeability, tracheal cross sections were stained with naphthol AS-D chloroacetate and PMNs were scored by their location as well as staining characteristics (positive or negative). The total PMN population remained at the control value at the 0-, 4-, and 8-hr time points, and increased at 12 hr, followed by a rapid decline to below the control value for the remaining time points. There was a shift at the 8-hr time point in the population location, from the vasculature to the interstitium, which returned to control values at 12 hr. The percentage stained PMNs increased significantly at 16 hr while remaining at control values for all other time points. The data reveal that there is a significant increase in tracheal epithelial permeability immediately after the exposure, but the overall increase in the PMN population is preceded by a lag phase. A decrease in the vascular pool of PMNs concomitant with an increase in the interstitial pool of PMNs suggests their migration from blood to the interstitium after ozone exposure. These data indicate that while PMNs may play a role in permeability changes of tracheal epithelium, the initiation is most likely due to other factors.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    PubMed Central

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

    2015-01-01

    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

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

    PubMed

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

    2015-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Amirnasr, Elham

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

  12. Brain perfusion and permeability in patients with advanced, refractory glioblastoma treated with lomustine and the transforming growth factor-? receptor I kinase inhibitor LY2157299 monohydrate

    PubMed Central

    SEPULVEDA-SANCHEZ, JUAN; RAMOS, ANA; HILARIO, AMAYA; DE VELASCO, GUILLERMO; CASTELLANO, DANIEL; GARCIA DE LA TORRE, MARTA; RODON, JORDI; LAHN, MICHAEL F.

    2015-01-01

    Transforming growth factor-? (TGF-?) signaling is associated with tumor progression and vascularization in malignant glioma. In the present study, magnetic resonance imaging was used to evaluate changes in the size and vascularity of glioblastomas in 12 patients who were treated with lomustine and the novel inhibitor of TGF-? signaling, LY2157299 monohydrate. A response in tumor size was observed in 2 of the 12 patients; in 1 of these 2 patients, a reduction in vascular permeability and perfusion was also detected. The effect was observed following 4 cycles of treatment (~3 months). Changes in vascularity have not previously been attributed to treatment with lomustine; therefore, the effect may be associated with LY2157299 treatment. LY2157299 does not appear to have an anti-angiogenic effect when combined with lomustine, and hence may have a different mechanism of action profile compared with anti-angiogenic drugs.

  13. Expression and significance of ?-SMA and PCNA in the vascular adventitia of balloon-injured rat aorta

    PubMed Central

    WU, XIANGJUN; LU, QINGHUA

    2013-01-01

    The aim of this study was to investigate changes in the expression of ?-smooth muscle actin (?-SMA) and proliferating cell nuclear antigen (PCNA) in the vascular adventitia of balloon-injured rat aortas in the second and sixth postoperative weeks. A total of 32 rats were divided into a control group and a balloon-injured group. The rats underwent vascular morphometric analysis and adventitial cell counting, as well as immunohistochemical staining of ?-SMA and PCNA in postoperative weeks 2 and 6 for observation of the expression of each immune parameter in the vascular adventitia and calculation of the number of PCNA-positive nuclei and the PCNA labeling index (PCNALI) in the vascular adventitia. The area and thickness of the adventitia, the number of nuclei and the PCNALI of the vascular adventitia were significantly increased in the injured group compared with the control group (P<0.05), while the external elastic lamina area (EELA), internal elastic lamina area (IELA) and lumen area (LA) were significantly decreased (P<0.05) in the second week. The area and thickness of the adventitia, the number of nuclei and the PCNALI of the vascular adventitia were significantly increased in the injured group compared with the control group (P<0.05), while the EELA, IELA and LA were significantly reduced (P<0.05) in the sixth week, and were significantly lower than those in the injured group in the second week (P<0.05). The positive expression levels of ?-SMA and PCNA in the vascular adventitia were significantly reduced compared with those in the second week after injury. The vascular adventitial cells underwent proliferation and phenotypic switching and participated in vascular remodeling and vascular restenosis following balloon-induced injury. The vascular contractile remodeling in the injured group was more evident in the sixth week than in the second week, followed by a more aggravated vascular stenosis. Consequently, the vascular remodeling was one of the causes of vascular restenosis. PMID:23837052

  14. Stress-sensitive permeability in a high-permeability sandstone reservoir--The Kuparuk field. [Alaska

    SciTech Connect

    Adams, B.H.

    1983-03-01

    Buildup test analyses for wells in the Kuparuk field, Alaska, give permeability values that are two to seven times higher than values from drawdown test analyses. Often buildup skins indicate extreme formation damage, while drawdown skins indicate minimal damage. This sandstone reservoir exhibits the characteristics of stress-sensitive permeability. The existence of stress-sensitive permeability was demonstrated using well test analyses, simulation studies, core analyses, and laboratory flow experiments. Comparisons were made for most wells in the field, with significant differences between buildups and drawdowns evident in a majority of the analyses. Simulation of well tests required stress-sensitive permeability to match both buildup and drawdown tests. Core analyses and laboratory flow tests were done to determine the cause and magnitude of the stress-sensitive permeability. Evidence points to open vertical fractures as the cause of this stress-sensitive permeability. These fractures are small-scale, with characteristic heights on the order of inches, and apparently randomly distributed in the reservoir. Because of the fractures' size and distribution, the reservoir behaves as a homogeneous porous medium with stress-sensitive permeability rather than as a classical naturally fractured reservoir. Well tests show no typical fractured reservoir behavior (i.e., linear flow). The extreme effects of stress-sensitive permeability, as seen in this reservoir, can seriously impact field operations.

  15. 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...

  16. Honeycomb Core Permeability Under Mechanical Loads

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

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

    PubMed Central

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

    2013-01-01

    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

  18. Vascular disease of the spine.

    PubMed

    Munyon, Charles N; Hart, David J

    2015-05-01

    Vascular insults to the spinal cord are substantially less common than their corresponding events in the brain; it has been estimated, for example, that spinal cord infarcts make up ?1% of ischemic events in the central nervous system. Although the public health burden of spinal cord injury remains severe, the majority of this burden stems from traumatic rather than vascular events. Still, vascular injuries in the spine are common enough and their consequences devastating enough that a familiarity with the pathophysiology, diagnosis, and treatment of the more common etiologies is essential to any practitioner of the clinical neurosciences. In this educational review, we will briefly outline the normal development and anatomy of the spinal vasculature, then focus on specific mechanisms of vascular injury to the spine. In particular, we will examine spontaneous and iatrogenic ischemic insults and their associated clinical syndromes, and then review vascular neoplasms and malformations of the spine with attention to the various management strategies that currently exist for these complex lesions. Finally, we will briefly address the future areas for exploration, including investigative avenues for neuroprotection, as well as the possible influence of atherosclerotic disease on spinal degenerative disease and low back pain. PMID:25970833

  19. Differential Apicobasal VEGF Signaling at Vascular Blood-Neural Barriers

    PubMed Central

    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

    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

  20. Permeability comparison between hepatocyte and low efflux MDCKII cell monolayer.

    PubMed

    Li, Rui; Bi, Yi-An; Lai, Yurong; Sugano, Kiyohiko; Steyn, Stefanus J; Trapa, Patrick E; Di, Li

    2014-07-01

    Determination of passive permeability is not only important for predicting oral absorption and brain penetration, but also for accurately predicting hepatic clearance. High throughput (HT) measurement of passive permeability across hepatocyte cell membrane is technically more challenging than using monolayer cell-based permeability assays. In this study, we evaluated if the HT Madin-Darby canine kidney II-low efflux (MDCKII-LE) cell monolayer permeability assay can be used as a surrogate to predict the passive permeability of hepatocytes. Apparent passive permeability of MDCKII-LE is well correlated to passive diffusion clearance of human and rat hepatocytes, suggesting that the HT MDCKII-LE assay can be used as a surrogate to estimate the passive permeability of hepatocytes. In addition, lipophilicity (Log D determined at pH 7.4) was also found to be well correlated with both MDCKII-LE and hepatocyte permeability for most compounds, hence it may serve as another permeability surrogate. PMID:24854896

  1. High permeability fracturing of gas wells

    SciTech Connect

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

    1998-01-01

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

  2. GROUNDWATER FLOW IN LOW-PERMEABILITY ENVIRONMENTS.

    USGS Publications Warehouse

    Neuzil, C.E.

    1986-01-01

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

  3. Negative index metamaterial combining magnetic resonators with metal films

    Microsoft Academic Search

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

    2006-01-01

    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.

  4. The effect of heat on skin permeability

    PubMed Central

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

    2008-01-01

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

  5. Development of an Improved Permeability Modification Simulator

    SciTech Connect

    Gao, H.W.; Elphnick, J.

    1999-03-09

    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.

  6. Magnetic permeability measurements and a lunar core

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  7. Lipid membrane with low proton permeability.

    PubMed

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

    2003-04-01

    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

  8. Axitinib modulates hypoxia-induced blood-retina barrier permeability and expression of growth factors.

    PubMed

    Kernt, Marcus; Thiele, Sarah; Liegl, Raffael G; Kernt, Barbara; Eibl, Kirsten; Haritoglou, Christos; Ulbig, Michael W; Kampik, Anselm

    2012-02-01

    This study investigates the effects of the multikinase inhibitor axitinib on the expression of vascular endothelial growth factor (VEGF) receptors 1/2 (VEGFR-1/2) and platelet-derived growth factor (PDGF) receptor beta (PDGFR-?), hypoxia-induced increased tissue permeability, occludin, zonula occludens protein 1 (ZO-1), VEGF-A, and PDGF expression of human retinal pigment epithelial (RPE) cells and human umbilical vein endothelial cells (HUVECs). Primary human RPE cells and HUVECs were exposed to hypoxia and axitinib. Viability of cells, tissue permeability, and expression of occludin, ZO-1, VEGF, PDGF, VEGFR-1/2 and PDGFR-?, and their mRNAs, were investigated by reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, and immunohistochemistry. Treatment with axitinib reduced expression of VEGFR-1/2 and PDGFR-?. Hypoxia decreased cell viability, occludin, and ZO-1 expression and increased tissue permeability, expression, and secretion of VEGF and PDGF. Axitinib significantly reduced hypoxia-induced effects on HUVEC and RPE cells. Our in vitro results suggest that axitinib may have promising properties as a potential treatment for diabetic macular edema. PMID:22168366

  9. Angiopoietin-1 Regulates Brain Endothelial Permeability through PTPN-2 Mediated Tyrosine Dephosphorylation of Occludin

    PubMed Central

    Siddiqui, M. Rizwan; Mayanil, Chandra S.; Kim, Kwang Sik; Tomita, Tadanori

    2015-01-01

    Objective Blood brain barrier (BBB) breakdown and increased endothelial permeability is a hallmark of neuro-vascular inflammation. Angiopoietin-1 (Ang-1), a Tie-2 receptor agonist ligand, is known to modulate barrier function of endothelial cells; however the molecular mechanisms related to Ang-1 mediated repair of Tight Junctions (TJs) in brain endothelium still remain elusive. In this study, we investigated a novel role of non-receptor protein tyrosine phosphatase N-2 (PTPN-2) in Ang-1 mediated stabilization of tight junction proteins. Method and Result To study the barrier protective mechanism of Ang-1, we challenged human brain microvascular endothelial cells in-vitro, with a potent inflammatory mediator thrombin. By using confocal microscopy and transwell permeability assay, we show that pretreatment of brain endothelial cells with Ang-1 diminish thrombin mediated disruption of TJs and increase in endothelial permeability. We also found that Ang-1 inhibits thrombin induced tyrosine phosphorylation of Occludin and promote Occludin interaction with Zona Occludens-1 (ZO-1) to stabilize TJs. Interestingly, our study revealed that depletion of PTPN-2 by siRNAs abolishes Ang-1 ability to promote tyrosine dephosphorylation of Occludin, resulting Occludin disassociation from ZO-1 and endothelial hyperpermeability. Summary Collectively, our findings suggest that in brain endothelial cells blocking PTPN-2 mediated tyrosine phosphorylation of Occludin is a novel mechanism to maintain BBB function, and may offer a key therapeutic strategy for neuro-inflammatory disorders associated with BBB disruption. PMID:26090670

  10. Critical role of PBEF expression in pulmonary cell inflammation and permeability.

    PubMed

    Liu, Peng; Li, Hailong; Cepeda, Javier; Zhang, Li Qin; Cui, Xiuyun; Garcia, Joe G N; Ye, Shui Qing

    2009-01-01

    Previous studies in our lab have identified pre-B-cell colony enhancing factor (PBEF) as a novel biomarker in acute lung injury. This study continues to elucidate the underlying molecular mechanism of PBEF in the pathogenesis of acute lung injury in pulmonary cell culture models. Our results revealed that IL-1beta induced PBEF expression in pulmonary vascular endothelial cells at the transcriptional level and a -1535 T-variant in the human PBEF gene promoter significantly attenuated its binding to an IL-1beta-induced unknown transcription factor. This may underlie the reduced expression of PBEF and thus the lower susceptibility to acute lung injury in -1535T carriers. Furthermore, overexpression of PBEF significantly augmented IL-8 secretion and mRNA expression by more than 6-fold and 2-fold in A549 cells and HPAEC, respectively. It also significantly augmented IL-1beta-mediated cell permeability by 44% in A549 cells and 65% in endothelial cells. The knockdown of PBEF expression significantly inhibited IL-1beta-stimulated IL-8 secretion and mRNA level by 60% and 70%, respectively, and the knockdown of PBEF expression also significantly attenuated IL-1beta-induced cell permeability by 29% in epithelial cells and 24% in endothelial cells. PBEF expression also affected the expression of two other inflammatory cytokines (IL-16 and CCR3 genes). These results suggest that PBEF is critically involved in pulmonary vascular and epithelial inflammation and permeability, which are hallmark features in the pathogenesis of acute lung injury. This study lends further support to our finding that PBEF is a potential new target in acute lung injury. PMID:18996492

  11. Vascular gene expression: a hypothesis

    PubMed Central

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    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.

  13. Indexing and Querying Avishek Anand

    E-print Network

    Nejdl, Wolfgang

    Indexing and Querying Avishek Anand #12;Avishek Anand Inverted Indexing basics revisited Indexing Static Collections Dictionaries Forward Index Inverted Index Organisation Scalable Indexing Indexing Dynamic Collections Inverted Index Construction and Maintenance 2 #12;Avishek Anand

  14. Refractive Index of Light in the Quark-Gluon Plasma with the Hard-Thermal-Loop Perturbation Theory

    Microsoft Academic Search

    Juan Liu; M. J. Luo; Qun Wang; Hao-jie Xu

    2011-01-01

    The electric permittivity and magnetic permeability for the quark-gluon plasma (QGP) is calculated within the hard-thermal-loop (HTL) perturbation theory. The refractive indices in the magnetizable and non-magnetizable plasmas are calculated. In a magnetizable plasma, there is a frequency pole $\\\\omega_{mp}$ in the magnetic permeability and the refractive index. The refractive index becomes negative in the range $\\\\omega\\\\in[k,\\\\omega_{mp}]$, where $k$ is

  15. Theoretical formulation for an electrically small microstrip patch antenna loaded with negative index materials

    Microsoft Academic Search

    J. S. Petko; D. H. Werner

    2005-01-01

    Composite metamaterials that possess simultaneously negative permeability and permittivity, causing them to exhibit a negative index of refraction known, are known as a negative index materials (NIM). An application of NIMs is to increase the power radiated from electrically small antennas. NIMs can also be used to design thin sub-wavelength cavity resonators. We expand on this principle by introducing a

  16. Pathogenic hantaviruses Andes virus and Hantaan virus induce adherens junction disassembly by directing vascular endothelial cadherin internalization in human endothelial cells.

    PubMed

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

    2010-07-01

    Hantaviruses infect endothelial cells and cause 2 vascular permeability-based diseases. Pathogenic hantaviruses enhance the permeability of endothelial cells in response to vascular endothelial growth factor (VEGF). However, the mechanism by which hantaviruses hyperpermeabilize endothelial cells has not been defined. The paracellular permeability of endothelial cells is uniquely determined by the homophilic assembly of vascular endothelial cadherin (VE-cadherin) within adherens junctions, which is regulated by VEGF receptor-2 (VEGFR2) responses. Here, we investigated VEGFR2 phosphorylation and the internalization of VE-cadherin within endothelial cells infected by pathogenic Andes virus (ANDV) and Hantaan virus (HTNV) and nonpathogenic Tula virus (TULV) hantaviruses. We found that VEGF addition to ANDV- and HTNV-infected endothelial cells results in the hyperphosphorylation of VEGFR2, while TULV infection failed to increase VEGFR2 phosphorylation. Concomitant with the VEGFR2 hyperphosphorylation, VE-cadherin was internalized to intracellular vesicles within ANDV- or HTNV-, but not TULV-, infected endothelial cells. Addition of angiopoietin-1 (Ang-1) or sphingosine-1-phosphate (S1P) to ANDV- or HTNV-infected cells blocked VE-cadherin internalization in response to VEGF. These findings are consistent with the ability of Ang-1 and S1P to inhibit hantavirus-induced endothelial cell permeability. Our results suggest that pathogenic hantaviruses disrupt fluid barrier properties of endothelial cell adherens junctions by enhancing VEGFR2-VE-cadherin pathway responses which increase paracellular permeability. These results provide a pathway-specific mechanism for the enhanced permeability of hantavirus-infected endothelial cells and suggest that stabilizing VE-cadherin within adherens junctions is a primary target for regulating endothelial cell permeability during pathogenic hantavirus infection. PMID:20463083

  17. Soak It Up: Understanding Amphibian Permeability

    NSDL National Science Digital Library

    Association of Zoos and Aquariums

    2009-01-01

    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!

  18. Image current inclusion in the permeable sphere

    Microsoft Academic Search

    D. V. Redzic; S. S. Redzic

    2006-01-01

    An interesting property of the magnetostatic image theory for a superconducting sphere in the field of a static circular current loop with its axis radial to the sphere is pointed out: the magnetic field outside the superconducting sphere remains unchanged if the superconductor is replaced by a permeable sphere with an embedded current loop which coincides with the image current

  19. A permeable rotating-wheel solvent extractor

    NASA Technical Reports Server (NTRS)

    Kahn, D. R.; Nady, L. A.

    1972-01-01

    Column-type device reported employs circular permeable structures of wire mesh screen for extracting solvents from systems with low density differences and low interfacial tensions. Rotating screen wheels of structure fasten to shaft; stationary screen structures are supported by circular bands connected by radial metal arms.

  20. Hydraulic fracturing pressures in permeable surface layers

    Microsoft Academic Search

    Hagoort

    1978-01-01

    A theoretical analysis is presented of hydraulic fracturing pressures in permeable subsurface layers situated in a tectonically relaxed area. The analysis is based on the theory of linear poro-elasticity. Three different fracturing pressures can be distinguished: (1) fracture initiation pressure: the pressure in the borehole needed to part undamaged rock around the borehole; (2) fracture opening\\/closing pressure: the pressure in

  1. PERMEABILITY OF SALTSTONE MEASUREMENT BY BEAM BENDING

    Microsoft Academic Search

    J. R. Harbour; T Tommy Edwards; V Vickie Williams

    2008-01-01

    One of the goals of the Saltstone variability study is to identify (and, quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. A performance property for Saltstone mixes that is important but not routinely measured is the liquid permeability or saturated hydraulic conductivity of the cured Saltstone

  2. Waveguide miniaturization using uniaxial negative permeability metamaterial

    Microsoft Academic Search

    Silvio Hrabar; Juraj Bartolic; Zvonimir Sipus

    2005-01-01

    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

  3. A microdevice for parallelized pulmonary permeability studies.

    PubMed

    Bol, Ludivine; Galas, Jean-Christophe; Hillaireau, Hervé; Le Potier, Isabelle; Nicolas, Valérie; Haghiri-Gosnet, Anne-Marie; Fattal, Elias; Taverna, Myriam

    2014-04-01

    We describe a compartmentalized microdevice specifically designed to perform permeability studies across a model of lung barrier. Epithelial cell barriers were reproduced by culturing Calu-3 cells at the air-liquid interface (AIC) in 1 mm² microwells made from a perforated glass slide with an embedded porous membrane. We created a single basolateral reservoir for all microwells which eliminated the need to renew the growth medium during the culture growth phase. To perform drug permeability studies on confluent cell layers, the cell culture slide was aligned and joined to a collection platform consisting in 35 ?L collection reservoirs connected at the top and bottom with microchannels. The integrity and functionality of the cell barriers were demonstrated by measurement of trans-epithelial electrical resistance (TEER), confocal imaging and permeability assays of ¹?C-sucrose. Micro-cell barriers were able to form confluent layers in 1 week, demonstrating a similar bioelectrical evolution as the Transwell systems used as controls. Tight junctions were observed throughout the cell-cell interfaces, and the low permeability coefficients of ¹?C-sucrose confirmed their functional presence, creating a primary barrier to the diffusion of solutes. This microdevice could facilitate the monitoring of biomolecule transport and the screening of formulations promoting their passage across the pulmonary barrier, in order to select candidates for pulmonary administration to patients. PMID:24337430

  4. Fluid permeabilities of triply periodic minimal surfaces.

    PubMed

    Jung, Y; Torquato, S

    2005-11-01

    It has recently been shown that triply periodic two-phase bicontinuous composites with interfaces that are the Schwartz primitive (P) and diamond (D) minimal surfaces are not only geometrically extremal but extremal for simultaneous transport of heat and electricity. The multifunctionality of such two-phase systems has been further established by demonstrating that they are also extremal when a competition is set up between the effective bulk modulus and electrical (or thermal) conductivity of the bicontinuous composite. Here we compute the fluid permeabilities of these and other triply periodic bicontinuous structures at a porosity using the immersed-boundary finite-volume method. The other triply periodic porous media that we study include the Schoen gyroid (G) minimal surface, two different pore-channel models, and an array of spherical obstacles arranged on the sites of a simple cubic lattice. We find that the Schwartz P porous medium has the largest fluid permeability among all of the six triply periodic porous media considered in this paper. The fluid permeabilities are shown to be inversely proportional to the corresponding specific surfaces for these structures. This leads to the conjecture that the maximal fluid permeability for a triply periodic porous medium with a simply connected pore space at a porosity is achieved by the structure that globally minimizes the specific surface. PMID:16383757

  5. Permeability of muscle capillaries to microperoxidase

    PubMed Central

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

    1978-01-01

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

  6. On the accuracy of electrochemical permeability measurements

    Microsoft Academic Search

    F. M Figueiredo; F. M. B Marques; J. R Frade

    1998-01-01

    A simple experimental setup, consisting of a closed chamber with two electrochemically active walls (the material being studied and one electrochemical pump), was designed to measure the electrochemical permeability of mixed conductors. The basic relations between material properties and measurable parameters are revised. Experiments showed that the quality of sealing is a critical issue to be taken into consideration. Careful

  7. Permeability-porosity relationship in vesicular basalts

    Microsoft Academic Search

    Martin O. Saar; Michael Manga

    1999-01-01

    The permeability k and porosity varphi of vesicular basalts are measured. The relationship between k and varphi reflects the formation and emplacement of the basalts and can be related to the crystal and vesicle microstructure obtained by image analysis. Standard theoretical models relating k and varphi that work well for granular materials are unsuccessful for vesicular rocks due to the

  8. The permeability barrier in mammalian epidermis

    Microsoft Academic Search

    PETER M. ELIAS; DANIEL S. FRIEND

    1975-01-01

    The structural basis of the permeability barrier in mammalian epidermis was examined by tracer and freeze-fracture techniques. Water-soluble tracers (horse- radish peroxidase, lanthanum, ferritin) were injected into neonatal mice or into isolated upper epidermal sheets obtained with staphylococcal exfoliatin. Tracers percolated through the intercellular spaces to the upper stratum granulosum, where further egress was impeded by extruded contents of lamellar

  9. KRIT1 protein depletion modifies endothelial cell behavior via increased vascular endothelial growth factor (VEGF) signaling.

    PubMed

    DiStefano, Peter V; Kuebel, Julia M; Sarelius, Ingrid H; Glading, Angela J

    2014-11-21

    Disruption of endothelial cell-cell contact is a key event in many cardiovascular diseases and a characteristic of pathologically activated vascular endothelium. The CCM (cerebral cavernous malformation) family of proteins (KRIT1 (Krev-interaction trapped 1), PDCD10, and CCM2) are critical regulators of endothelial cell-cell contact and vascular homeostasis. Here we show novel regulation of vascular endothelial growth factor (VEGF) signaling in KRIT1-depleted endothelial cells. Loss of KRIT1 and PDCD10, but not CCM2, increases nuclear ?-catenin signaling and up-regulates VEGF-A protein expression. In KRIT1-depleted cells, increased VEGF-A levels led to increased VEGF receptor 2 (VEGFR2) activation and subsequent alteration of cytoskeletal organization, migration, and barrier function and to in vivo endothelial permeability in KRIT1-deficient animals. VEGFR2 activation also increases ?-catenin phosphorylation but is only partially responsible for KRIT1 depletion-dependent disruption of cell-cell contacts. Thus, VEGF signaling contributes to modifying endothelial function in KRIT1-deficient cells and microvessel permeability in Krit1(+/-) mice; however, VEGF signaling is likely not the only contributor to disrupted endothelial cell-cell contacts in the absence of KRIT1. PMID:25320085

  10. [Malignant vascular tumors of the vulva].

    PubMed

    Chokoeva, A; Tchernev, G

    2015-01-01

    Due to the increased vascularity as well as the unique anatomical structure, vascular lesions, which occur in the female reproductive system are common observed and diverse by their morphology. The majority of them are benign, including vascular malformations, lesions due to vascular hyperplasia, tumors with significant vascular component and others. Malignant vascular tumors are rare in the area of the vulva accounting about 1% of all vulvar lesions with vascular origin. Kaposi sarcoma, epithelioid hemangioepithelioma and epithelioid angiosarcoma have been reported with vulvar localization. With a view to their rare incidence, nonspecific clinical manifestation and aggressive behavior associated with high mortality, we present the most common malignant tumors of vascular origin arising in the vulva, as we emphasize on their epidemiology and clinical features, differential diagnosis and therapeutic algorithms for this rare type of malignancies. PMID:25909132

  11. Vascular injury in the United kingdom.

    PubMed

    Stannard, Adam; Brohi, Karim; Tai, Nigel

    2011-03-01

    Surgeons working within the United Kingdom's National Health Service have an established history of clinical innovation, research, and development in the field of vascular surgery but lack a unified trauma system to deliver optimal care for patients with vascular injury. The low incidence of vascular trauma, combined with lack of regional trauma systems, works against optimal delivery of care to the polytrauma patient. Providing care, robust data capture, and opportunities for training and education in vascular injury lag behind other elective domains of vascular practice. The challenge is to define ideal care pathways, referral networks, and standards of practice and to integrate the care of such patients. In 2010, a trauma system for London was introduced; it has provided vascular surgeons with a unique opportunity to study and advance the care of patients with vascular injury. This article discusses developing trauma network issues, particularly the organization and evolution of vascular trauma services in the United Kingdom. PMID:21810810

  12. Effects of Urotensin II and Its Specific Receptor Antagonist Urantide on Rat Vascular Smooth Muscle Cells

    PubMed Central

    Zhao, Juan; Zhang, Shu-Feng; Shi, Yan; Ren, Li-Qun

    2013-01-01

    We investigated the effects of urantide, a receptor antagonist of urotensin II (U-II), on the expression of U-II and its receptor GPR14 in rat vascular smooth muscle cells. Vascular smooth muscle cells from rat thoracic aorta were cultured by explant method. Subjects in this experiment were divided into eight groups: normal control group (group C), U-II group (group M), positive control group (Flu group) and urantide-treated groups (10-10, 10-9, 10-8, 10-7 and 10-6 mol/L). Cultured vascular smooth muscle cells in vitro were studied by immunocytochemistry, biochemistry, and flow cytometry. U-II (10-8 mol/L) promoted the proliferation of vascular smooth muscle cells at each time point, influenced cell cycle, increased proliferation index and S-phase cell fraction, and dramatically promoted the expression of U-II and GPR14. In the concentration range from 10-10 to 10-6 mol/L, urantide dramatically inhibited the proliferation of vascular smooth muscle cells and the protein expression of U-II and GPR14, especially at a concentration of 10-6 mol/L. U-II, binding with its receptor GPR14, promotes vascular smooth muscle cells proliferation and migration, which can be inhibited by urantide. This study provides an evidence for understanding the effects of U-II and its receptor GPR14 on vascular smooth muscle cells. PMID:23725502

  13. Targeting Abl kinases to regulate vascular leak during sepsis and acute respiratory distress syndrome.

    PubMed

    Rizzo, Alicia N; Aman, Jurjan; van Nieuw Amerongen, Geerten P; Dudek, Steven M

    2015-05-01

    The vascular endothelium separates circulating fluid and inflammatory cells from the surrounding tissues. Vascular leak occurs in response to wide-spread inflammatory processes, such as sepsis and acute respiratory distress syndrome, because of the formation of gaps between endothelial cells. Although these disorders are leading causes of mortality in the intensive care unit, no medical therapies exist to restore endothelial cell barrier function. Recent evidence highlights a key role for the Abl family of nonreceptor tyrosine kinases in regulating vascular barrier integrity. These kinases have well-described roles in cancer progression and neuronal morphogenesis, but their functions in the vasculature have remained enigmatic until recently. The Abl family kinases, c-Abl (Abl1) and Abl related gene (Arg, Abl2), phosphorylate several cytoskeletal effectors that mediate vascular permeability, including nonmuscle myosin light chain kinase, cortactin, vinculin, and ?-catenin. They also regulate cell-cell and cell-matrix junction dynamics, and the formation of actin-based cellular protrusions in multiple cell types. In addition, both c-Abl and Arg are activated by hyperoxia and contribute to oxidant-induced endothelial cell injury. These numerous roles of Abl kinases in endothelial cells and the current clinical usage of imatinib and other Abl kinase inhibitors have spurred recent interest in repurposing these drugs for the treatment of vascular barrier dysfunction. This review will describe the structure and function of Abl kinases with an emphasis on their roles in mediating vascular barrier integrity. We will also provide a critical evaluation of the potential for exploiting Abl kinase inhibition as a novel therapy for inflammatory vascular leak syndromes. PMID:25814671

  14. Deformable isosurface and vascular applications

    NASA Astrophysics Data System (ADS)

    Yim, Peter J.; Vasbinder, G. Boudewijn; Ho, Vincent B.; Choyke, Peter L.

    2002-05-01

    Vascular disease produces changes in lumenal shape evident in magnetic resonance angiography (MRA). However, quantification of vascular shape from MRA is problematic due to image artifacts. Prior deformable models for vascular surface reconstruction primarily resolve problems of initialization of the surface mesh. However, initialization can be obtained in a trivial manner for MRA using isosurfaces. We propose a methodology for deforming the isosurface to conform to the boundaries of objects in the image with minimal a priori assumptions of object shape. As in conventional methods, external forces attract the surface towards edges in the image. However, smoothing is produced by torsional forces that align the normals of adjacent surface triangles. The torsional forces are unbiased with regard to determination of object size. The deformable isosurface was applied to MRA of carotid and renal arteries with moderate stenosis and to a digital phantom of an artery with high-grade stenosis (6-voxel normal diameter). The reconstruction of the carotid and renal arteries from MRA was entirely consistent with expert interpretation of the MRA. The deformable isosurface determined the degree of stenosis of the digital phantom to within 10.0% accuracy. The deformable isosurface is an excellent method for analysis of vascular shape.

  15. Renal Vascular Resistance in Sepsis

    Microsoft Academic Search

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

    2006-01-01

    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

  16. Vascular Parkinsonism: Deconstructing a Syndrome.

    PubMed

    Vizcarra, Joaquin A; Lang, Anthony E; Sethi, Kapil D; Espay, Alberto J

    2015-06-01

    Progressive ambulatory impairment and abnormal white matter (WM) signal on neuroimaging come together under the diagnostic umbrella of vascular parkinsonism (VaP). A critical appraisal of the literature, however, suggests that (1) no abnormal structural imaging pattern is specific to VaP; (2) there is poor correlation between brain MRI hyperintensities and microangiopathic brain disease and parkinsonism from available clinicopathologic data; (3) pure parkinsonism from vascular injury ("definite" vascular parkinsonism) consistently results from ischemic or hemorrhagic strokes involving the SN and/or nigrostriatal pathway, but sparing the striatum itself, the cortex, and the intervening WM; and (4) many cases reported as VaP may represent pseudovascular parkinsonism (e.g., Parkinson's disease or another neurodegenerative parkinsonism, such as PSP with nonspecific neuroimaging signal abnormalities), vascular pseudoparkinsonism (e.g., akinetic mutism resulting from bilateral mesial frontal strokes or apathetic depression from bilateral striatal lacunar strokes), or pseudovascular pseudoparkinsonism (e.g., higher-level gait disorders, including normal-pressure hydrocephalus with transependimal exudate). These syndromic designations are preferable over VaP until pathology or validated biomarkers confirm the underlying nature and relevance of the leukoaraiosis. © 2015 International Parkinson and Movement Disorder Society. PMID:25997420

  17. Tissue engineering of vascular grafts

    Microsoft Academic Search

    Anthony Ratcliffe

    2000-01-01

    The challenge of tissue engineering blood vessels with the mechanical properties of native vessels, and with the anti-thrombotic properties required is immense. Recent advances, however, indicate that the goal of providing a tissue-engineered vascular graft that will remain patent in vivo for substantial periods of time, is achievable. For instance, collagen gels have been used to fabricate a tissue in

  18. Vascular origin of Poland syndrome?

    Microsoft Academic Search

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

    1978-01-01

    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

  19. Superoxide in the Vascular System

    Microsoft Academic Search

    Michael S. Wolin; Sachin A. Gupte; Richard A. Oeckler

    2002-01-01

    Oxidant production and regulation is becoming increasingly important in the study of vascular signaling mechanisms, and recent reviews have characterized some of the possible roles for known downstream products of superoxide formation. In this review, we will examine current research in the field, with a special emphasis on the role of the superoxide molecule itself and its place amongst the

  20. Does Uremia Cause Vascular Dysfunction?

    Microsoft Academic Search

    Philippe Brunet; Bertrand Gondouin; Ariane Duval-Sabatier; Laetitia Dou; Claire Cerini; Françoise Dignat-George; Noémie Jourde-Chiche; Angel Argiles; Stéphane Burtey

    2011-01-01

    Vascular dysfunction induced by uremia has 4 main aspects. (1) Atherosclerosis is increased. Intima-media thickness is increased, and animal studies have established that uremia accelerates atherosclerosis. Uremic toxins are involved in several steps of atherosclerosis. Leukocyte activation is stimulated by guanidines, advanced glycation end products (AGE), p-cresyl sulfate, platelet diadenosine polyphosphates, and indoxyl sulfate. Endothelial adhesion molecules are stimulated by

  1. Notch3 establishes brain vascular integrity by regulating pericyte number.

    PubMed

    Wang, Yuying; Pan, Luyuan; Moens, Cecilia B; Appel, Bruce

    2014-01-01

    Brain pericytes are important regulators of brain vascular integrity, permeability and blood flow. Deficiencies of brain pericytes are associated with neonatal intracranial hemorrhage in human fetuses, as well as stroke and neurodegeneration in adults. Despite the important functions of brain pericytes, the mechanisms underlying their development are not well understood and little is known about how pericyte density is regulated across the brain. The Notch signaling pathway has been implicated in pericyte development, but its exact roles remain ill defined. Here, we report an investigation of the Notch3 receptor using zebrafish as a model system. We show that zebrafish brain pericytes express notch3 and that notch3 mutant zebrafish have a deficit of brain pericytes and impaired blood-brain barrier function. Conditional loss- and gain-of-function experiments provide evidence that Notch3 signaling positively regulates brain pericyte proliferation. These findings establish a new role for Notch signaling in brain vascular development whereby Notch3 signaling promotes expansion of the brain pericyte population. PMID:24306108

  2. The primary vascular dysregulation syndrome: implications for eye diseases

    PubMed Central

    2013-01-01

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

  3. Experimental Study on Rock Deformation and Permeability Variation

    E-print Network

    Ding, Jihui

    2013-08-01

    . This experimental study was carried out to investigate rock deformation and its impact on axial permeability. Triaxial compression tests were conducted on Berea sandstone, Indiana limestone, Westerly granite and tuff specimens. Axial permeability was continuously...

  4. Semi-analytical estimates of permeability obtained from capillary pressure 

    E-print Network

    Huet, Caroline Cecile

    2006-04-12

    The objective of this research is to develop and test a new concept for predicting permeability from routine rock properties. First, we develop a model predicting permeability as a function of capillary pressure. Our model, which is based...

  5. Permeability prediction and drainage capillary pressure simulation in sandstone reservoirs 

    E-print Network

    Wu, Tao

    2005-02-17

    Knowledge of reservoir porosity, permeability, and capillary pressure is essential to exploration and production of hydrocarbons. Although porosity can be interpreted fairly accurately from well logs, permeability and capillary pressure must...

  6. Vitreous Levels of Vascular Endothelial Growth Factor and Stromal-Derived Factor 1 in Patients With Diabetic Retinopathy and Cystoid Macular Edema Before and After Intraocular Injection of Triamcinolone

    Microsoft Academic Search

    H. Logan; Sergio Caballero; Charles K. Newell; Robert L. Steinmetz; Debbie Watson; Mark S. Segal; Jeffrey K. Harrison; Edward W. Scott; Maria B. Grant

    2004-01-01

    Background:Diffuse macular edema (DME) and\\/or ab- errantneovascularization(NV)cancausevisionlossindia- betic retinopathy (DR) and may be modulated by growth factorsandchemokines.Thechemokinestromal-derived factor 1 (SDF-1) is a potent stimulator of vascular endo- thelial growth factor (VEGF) expression, the main effec- tor of NV, and the key inducer of vascular permeability associatedwithDME.Circulatingendothelialcellprecur- sors migrating in response to SDF-1 participate in NV. Objective:ToinvestigatetherelationshipbetweenSDF-1 and (VEGF) in vitreous

  7. Time-resolved PIV measurements of flow around and through a permeable rectangular prism

    NASA Astrophysics Data System (ADS)

    Blois, G. L.; Barros, J. M.; Best, J. L.; Christensen, K. T.

    2012-11-01

    The unsteady turbulent wake dynamics generated by flow around and through a permeable rectangular prism is experimentally investigated using a refractive-index-matching (RIM) approach. A 7-mm diameter cylindrical flow passage was drilled through the center of an acrylic rectangular prism (25.5-mm thick; 51.0-mm long) along its streamwise axis. This permeable prism was then immersed in an aqueous solution (~ 63 % by weight) of sodium iodide (NaI) within a recirculating flow loop wherein the refractive index of the NaI was accurately matched to that of the acrylic prism via control of the NaI concentration and solution temperature. This RIM approach enabled simultaneous optical interrogation of the flow both around and within the permeable prism with time-resolved particle-image velocimetry at Re >104 . The interaction between the flow exiting the passage and the vortices shed from the model dramatically modifies the dynamics of the wake compared to that of a solid prism of identical dimensions. While the flow through the passage was found to be relatively steady, it generated a pulsating jet that penetrated into the wake, yielding strong internal-external flow interactions.

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

    PubMed Central

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

    2013-01-01

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

  9. Amplatzer Vascular Plug: Expanding the Applications Spectrum

    SciTech Connect

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

    2008-07-15

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

  10. Iatrogenic vascular injury during peripheral revascularization.

    PubMed

    Bunt, T J; Manship, L; Moore, W

    1985-05-01

    Iatrogenic vascular injury may occur during peripheral revascularization procedures secondary to the application of vascular occlusive devices. This review summarizes the known mechanical causes of such injury, relates this to clamp design, and suggests methods to minimize such injury by appropriate selection and handling of vascular occlusive clamps. PMID:3889383

  11. Permeability of deuterium and helium on poly(vinyl alcohol)

    Microsoft Academic Search

    Dean H. W. Carstens; E. P. Ehart

    1984-01-01

    The permeabilities of deuterium and helium-4 through poly (vinyl alcohol) (PVA) over the temperature range of 25-125) C are reported. For deuterium, permeabilities ranged from 0.5 X 10⁻¹⁸ mol-m\\/m²-s-Pa at these two extreme temperatures. Helium permeabilities were roughly five times higher. The effects of different curing temperatures and time on the deuterium permeability were studied found that, to within experimental

  12. Interaction of vortex rings with multiple permeable screens

    NASA Astrophysics Data System (ADS)

    Musta, Mustafa N.; Krueger, Paul S.

    2014-11-01

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

  13. Name: Department: GID #: Index #

    E-print Network

    Maxwell, Bruce D.

    Name: Department: GID #: Index #: (Current Index used to pay salary) In order to participate % of salary from my grant fund(s): % Index #: Beginning (mo./yr.): % Index #: Ending (mo./yr.): % Index #: % Index #: Total % (must have a minimum of 10% FTE to participate in the program) Do you have sufficient

  14. Permeability of continental crust influenced by internal and external forcing

    Microsoft Academic Search

    S. A. R OJSTACZER; S. E. IN; GEB RIT

    The permeability of continental crust is so highly variable that it is often considered to defy systematic character- ization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability-depth rela- tions) on a very large scale? Here we argue that large-scale crustal

  15. Impact of relative permeability hysteresis on geological CO2 storage

    Microsoft Academic Search

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

    2006-01-01

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

  16. Optimum mix design of enhanced permeable concrete – An experimental investigation

    Microsoft Academic Search

    C. Lian; Y. Zhuge

    2010-01-01

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

  17. Broadband permeability measurement method for ferrites at any magnetization

    E-print Network

    Paris-Sud XI, Université de

    Broadband permeability measurement method for ferrites at any magnetization state: direct problem jorge e. lezaca, patrick que'ffe'lec and alexis chevalier A broadband permeability measurement method in this paper is to develop an EM characterization method to measure a tensor quantity (permeability tensor

  18. Permittivity and Permeability Extraction of Magnetically Loaded Absorbing Materials

    E-print Network

    . To extract permittivity and permeability parameters from measured scattering parameters following approaches and permeability extraction needs both transmission and reflection measurements and is very sensitive to noisy dataPermittivity and Permeability Extraction of Magnetically Loaded Absorbing Materials I.Zivkovic, A

  19. Relative Permeability Hysteresis: Laboratory Measurements and a Conceptual Model

    Microsoft Academic Search

    E. M. Braun; R. F. Holland

    1995-01-01

    Relative permeability hysteresis has been measured for a water-wet outcrop rock sample and a mixed-wet reservoir core. For the oil phase, imbibition and drainage relative permeability curves differed significantly. The difference was much less pronounced for the water phase. Scanning curves, which characterize transitions between imbibition and drainage curves, were also measured. A notable characteristic of the oil relative permeability

  20. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Permeability of spaces. 172.185 Section 172...Special Rules Pertaining to a Ship That Carries a Bulk Liquefied...172.185 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  1. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Permeability of spaces. 172.185 Section 172...Special Rules Pertaining to a Ship That Carries a Bulk Liquefied...172.185 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  2. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Permeability of spaces. 172.185 Section 172...Special Rules Pertaining to a Ship That Carries a Bulk Liquefied...172.185 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  3. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Permeability of spaces. 172.140 Section 172...Special Rules Pertaining to a Ship That Carries a Hazardous Liquid...172.140 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  4. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Permeability of spaces. 172.185 Section 172...Special Rules Pertaining to a Ship That Carries a Bulk Liquefied...172.185 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  5. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Permeability of spaces. 172.185 Section 172...Special Rules Pertaining to a Ship That Carries a Bulk Liquefied...172.185 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  6. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Permeability of spaces. 172.140 Section 172...Special Rules Pertaining to a Ship That Carries a Hazardous Liquid...172.140 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  7. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Permeability of spaces. 172.140 Section 172...Special Rules Pertaining to a Ship That Carries a Hazardous Liquid...172.140 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  8. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Permeability of spaces. 172.140 Section 172...Special Rules Pertaining to a Ship That Carries a Hazardous Liquid...172.140 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  9. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Permeability of spaces. 172.140 Section 172...Special Rules Pertaining to a Ship That Carries a Hazardous Liquid...172.140 Permeability of spaces. (a) When doing the calculations...the permeability of a floodable space other than a machinery...

  10. Original article Permeability of milk protein antigens across the intestinal

    E-print Network

    Paris-Sud XI, Université de

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

  11. [Vascular Calcification - Pathological Mechanism and Clinical Application - . Vascular calcification in aged mice].

    PubMed

    Akiyoshi, Takuyu; Ogawa, Sumito; Akishita, Masahiro

    2015-01-01

    Vascular calcification is a risk factor for cerebral and cardiovascular events and has a high prevalence among elderly. To finding ways of prevent or cure vascular calcification may leads to not only a healthy longevity but also medical expenditure reduction. However, the molecular mechanism underlying this pathogenic process is still obscure. To clarify the mechanism of vascular calcification, the development of animal models that exhibit extensive and robust vascular calcification is an important issue for research in vascular biology. PMID:25926570

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

    USGS Publications Warehouse

    Nelson, Philip H.; Kibler, Joyce E.

    2003-01-01

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

  13. Tumor vascular volume determines photosensitizer uptake in MATLyLu prostate tumor model

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaodong; Chen, Bin; Hoopes, P. Jack; Hasan, Tayyaba; Pogue, Brian W.

    2007-02-01

    The parameters which limit supply of photosensitizer to the cancer cells in a solid tumor were systematically analyzed using microvascular transport modeling and histology data from frozen sections. In particular the vascular permeability transport coefficient and the effective interstitial diffusion coefficient were quantified for verteporfin-for-injection delivery of benzoporphyrin derivative (BPD). Orthotopic tumors had a higher permeability and diffusion coefficients (P d= 0.036 ?m/s and D = 1.6 ?m2/s, respectively) as compared to subcutaneously grown tumors (P d = 0.025 ?m/s and D = 0.9 ?m2/s, respectively), likely due to the fact that the vessel patterns are more homogeneous orthotopically. In general, large inter-subject and intra-tumor variability exist in the verteporfin concentration, in the range of 25% in plasma concentration and in the range of 20% for tissue concentrations, predominantly due to these micro-regional variations in transport. However, the average individual uptake of photosensitizer in tumor tissue was only correlated to the total vascular area within the tumor (R2 = 64.1%, p < 0.001). The data is consistent with a view that micro-regional variation in the vascular permeability, interstitial diffusion rate, all contributes the spatial heterogeneity observed in verteporfin uptake, but that average supply to the tissue is limited by the total area of perfused blood vessels. This study presents a method to systematically analyze microheterogeneity as well as possible methods to increase delivery and homogeneity of photosensitizer within tumor tissue.

  14. Acids aided by microemulsions increase permeability

    SciTech Connect

    Gardner, T.R.; Wood, F. (Halliburton Services, Duncan, OK (US))

    1989-07-01

    This article reports how, in more than 200 acid stimulation jobs recently performed on Kansas wells, operators have gained up to fourfold production increases by incorporating microemulsions into their acid treatments. Most of the 200 wells so treated had already been acidized conventionally, yielding disappointing results. The effect of properly formulated microemulsions on acid stimulation solutions is to allow the acid to sweep oil through pore spaces to penetrate further into formation rock at lower injection pressure. Deeper penetration with live acid consequently results in permeability increases for more formation area. Microemulsion systems (MES) also aid in faster cleanup of acidizing fluids since the MES reduces crude oil saturation in the near-well bore area; relative permeability is thus increased and water-based acid treatment moves more freely through the formation.

  15. Selective gel system for permeability profile control

    SciTech Connect

    Shu, P.

    1990-02-27

    This patent describes a process for closing pores in a more permeable zone of a formation. It comprises: placing into an aqueous solution a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises a xanthan biopolymer, and a transitional metal ion; placing into the aqueous solution a second composition sufficient to form thermally a second in-situ gel which is substantially more resistant to formation conditions than the first gel. The composition comprises an aldehyde, and a phenolic compound; allowing the aqueous solution sufficient time to form the ex-situ gel; and injecting the aqueous solution containing the gel into the permeable zone where it reheals, is heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than the first gel.

  16. Selective gel system for permeability profile control

    SciTech Connect

    Shu, P.

    1990-10-16

    This patent describes a selective gel for closing pores in a more permeable zone of a formation. It comprises: an aqueous solution of a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises a xanthan biopolymer, and a transitional metal ion; and an aqueous solution of a second composition sufficient to form thermally a second in-situ gel that which comprises and aldehyde, and a phenolic compound which solutions are combined and allowed to form a shearable, rehealable ex-situ gel which can be injected into the permeable zone where it reheals when heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than the first gel.

  17. Amyloid Triggers Extensive Cerebral Angiogenesis Causing Blood Brain Barrier Permeability and Hypervascularity in Alzheimer's Disease

    PubMed Central

    Biron, Kaan E.; Dickstein, Dara L.; Gopaul, Rayshad; Jefferies, Wilfred A.

    2011-01-01

    Evidence of reduced blood-brain barrier (BBB) integrity preceding other Alzheimer's disease (AD) pathology provides a strong link between cerebrovascular angiopathy and AD. However, the “Vascular hypothesis”, holds that BBB leakiness in AD is likely due to hypoxia and neuroinflammation leading to vascular deterioration and apoptosis. We propose an alternative hypothesis: amyloidogenesis promotes extensive neoangiogenesis leading to increased vascular permeability and subsequent hypervascularization in AD. Cerebrovascular integrity was characterized in Tg2576 AD model mice that overexpress the human amyloid precursor protein (APP) containing the double missense mutations, APPsw, found in a Swedish family, that causes early-onset AD. The expression of tight junction (TJ) proteins, occludin and ZO-1, were examined in conjunction with markers of apoptosis and angiogenesis. In aged Tg2576 AD mice, a significant increase in the incidence of disrupted TJs, compared to age matched wild-type littermates and young mice of both genotypes, was directly linked to an increased microvascular density but not apoptosis, which strongly supports amyloidogenic triggered hypervascularity as the basis for BBB disruption. Hypervascularity in human patients was corroborated in a comparison of postmortem brain tissues from AD and controls. Our results demonstrate that amylodogenesis mediates BBB disruption and leakiness through promoting neoangiogenesis and hypervascularity, resulting in the redistribution of TJs that maintain the barrier and thus, provides a new paradigm for integrating vascular remodeling with the pathophysiology observed in AD. Thus the extensive angiogenesis identified in AD brain, exhibits parallels to the neovascularity evident in the pathophysiology of other diseases such as age-related macular degeneration. PMID:21909359

  18. Pigment epithelium-derived factor regulates microvascular permeability through adipose triglyceride lipase in sepsis.

    PubMed

    He, Ting; Hu, Jiongyu; Yan, Guangning; Li, Lingfei; Zhang, Dongxia; Zhang, Qiong; Chen, Bing; Huang, Yuesheng

    2015-07-01

    The integrity of the vascular barrier, which is essential to blood vessel homoeostasis, can be disrupted by a variety of soluble permeability factors during sepsis. Pigment epithelium-derived factor (PEDF), a potent endogenous anti-angiogenic molecule, is significantly increased in sepsis, but its role in endothelial dysfunction has not been defined. To assess the role of PEDF in the vasculature, we evaluated the effects of exogenous PEDF in vivo using a mouse model of cecal ligation and puncture (CLP)-induced sepsis and in vitro using human dermal microvascular endothelial cells (HDMECs). In addition, PEDF was inhibited using a PEDF-monoclonal antibody (PEDF-mAb) or recombinant lentivirus vectors targeting PEDF receptors, including adipose triglyceride lipase (ATGL) and laminin receptor (LR). Our results showed that exogenous PEDF induced vascular hyperpermeability, as measured by extravasation of Evan's Blue (EB), dextran and microspheres in the skin, blood, trachea and cremaster muscle, both in a normal state and under conditions of sepsis. In control and LR-shRNA-treated HDMECs, PEDF alone or in combination with inflammatory mediators resulted in activation of RhoA, which was accompanied by actin rearrangement and disassembly of intercellular junctions, impairing endothelial barrier function. But in ATGL-shRNA-treated HDMECs, PEDF failed to induce the aforementioned alterations, suggesting that PEDF-induced hyperpermeability was mediated through the ATGL receptor. These results reveal a novel role for PEDF as a potential vasoactive substance in septic vascular hyperpermeability. Furthermore, our results suggest that PEDF and ATGL may serve as therapeutic targets for managing vascular hyperpermeability in sepsis. PMID:25700221

  19. Tetrahydrobiopterin, Superoxide and Vascular Dysfunction

    PubMed Central

    Vásquez-Vivar, Jeannette

    2009-01-01

    (6R)-5,6,7,8-Tetrahydrobiopterin (BH4) is an endogenously produced pterin that is found widely distributed in mammalian tissues. BH4 works as a cofactor of aromatic amino acid hydroxylases and nitric oxide synthases. In the vasculature a deficit of BH4 is implicated in the mechanisms of several diseases including atherosclerosis, hypertension, diabetic vascular disease, and vascular complications from cigarette smoking and environmental pollution. These ill-effects are connected to the ability of BH4 to regulate reactive oxygen species levels in the endothelium. The possibility of using BH4 as a therapeutical agent in cardiovascular medicine is becoming more compelling and many biochemical and physiological aspects involved in this application are currently under investigation. This review summarizes our current understanding of BH4 reactivity and some aspects of cellular production and regulation. PMID:19628033

  20. Vascular elastography: a validation study.

    PubMed

    Lopata, Richard G P; Peters, Mathijs F J; Nijs, Jan; Oomens, Cees W J; Rutten, Marcel C M; van de Vosse, Frans N

    2014-08-01

    Vascular elastography techniques are promising tools for mechanical characterization of diseased arteries. These techniques are usually validated with simulations or phantoms or by comparing results with histology or other imaging modalities. In the study described here, vascular elastography was applied to porcine aortas in vitro during inflation testing (n = 10) and results were compared with those of standard bi-axial tensile testing, a technique that directly measures the force applied to the tissue. A neo-Hookean model was fit to the stress-strain data, valid for large deformations. Results indicated good correspondence between the two techniques, with GUS = 110 ± 11 kPa and GTT = 108 ± 10 kPa for ultrasound and tensile testing, respectively. Bland-Altman analysis revealed little bias (GUS-GTT = 2 ± 20 kPa). The next step will be the application of a non-linear material model that is also adaptable for in vivo measurements. PMID:24798385

  1. Comparing guided modal properties of surface waves along single- and double-negative indexed slab waveguides

    Microsoft Academic Search

    K. Y. Kim; Y. K. Cho

    2010-01-01

    The guided dispersion characteristics of the fundamental symmetric and asymmetric modes of surface waves along single- and\\u000a double-negative indexed slab waveguides are investigated, and a comparative analysis made when varying the single- and double-negative\\u000a permittivity and permeability. While the values of the permittivity and permeability of the slab region are varied to obtain\\u000a a salient picture of the guided dispersion

  2. Methods of determining permeability, transmissibility and drawdown

    USGS Publications Warehouse

    Bentall, Ray

    1964-01-01

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

  3. Microwave complex permeability and permittivity of nanoferrites

    Microsoft Academic Search

    Anjali Sharma; Mohammed N. Afsar

    2011-01-01

    Complex permittivity and permeability of nanosized magnetic powders are studied for eight different bands to cover the frequency range from 2-40 GHz. A precise transmission-reflection based waveguide technique has been used to carry out measurements across the frequency bands. The algorithm for transmission and reflection calculations has been modified to account for variable sample thickness in the in-waveguide measurement setup.

  4. Chemical modulation of alveolar epithelial permeability.

    PubMed Central

    Gatzy, J T; Stutts, M J

    1980-01-01

    The volume and composition of fluid on the surface of the alveoli can affect alveolar ventilation, gas diffusion, and macrophage function. The passive permeability and active processes of the alveolar epithelial lining play a role in regulating surface fluid and are a potential site of damage by airborne chemicals. Like other epithelial barriers, the alveolar lining is permeable to lipophilic substances but restricts the transmural flow of small ions and hydrophilic nonelectrolytes (equivalent pore radius ca. 0.5-1.5 nm). The mammalian fetal lung and alveolar sacs of the adult bullfrog secrete Cl- and K+ into the airspace. Secretion by the fetal lung ceases at birth. Many environmental agents increase the permeability of the capillary endothelium and/or respiratory epithelium and induce pulmonary edema. Studies with bullfrog alveolar sacs have demonstrated that selective effects may or may not be followed by general derangement of the epithelial barrier. Exposure of the luminal surface to HgCl2 (10(-6) to 10(-4) M) induces a selective increase in Cl- secretion that is followed by a fall in transport and a general increase in ion permeation. CdCl2 (10(-5) to 10(-3) M) depresses ciliomotion on cells on the trabecula of the alveolus but does not affect Cl- secretion or transepithelial conductance. HNO3, like other mineral acids, increases conductance and the radii or pores in the barrier, whereas NaNO3 selectively inhibits Cl- secretion. Amphotericin B(10(7) to 10(-5) MJ) induces K+ secretion into the lumen of both bullfrog and rat lung. We conclude that environmental agents induce changes in epithelial function that may compromise the lung's ability to regulate respiratory fluid without destroying the characteristic permeability of the epithelial lining. PMID:6250808

  5. Association of Insulin Resistance Indexes to Carotid Intima–Media Thickness

    PubMed Central

    Sciacqua, Angela; Marini, Maria Adelaide; Hribal, Marta Letizia; Perticone, Francesco; Sesti, Giorgio

    2013-01-01

    Objectives Accumulating evidence suggests an association between insulin resistance (IR) and cardiovascular diseases The aim of this study was to examine the relationship between indexes of IR and common carotid intima–media thickness (IMT), an indicator of vascular damage. Methods In 847 non-diabetic Caucasians a 75 g oral glucose tolerance test was performed and surrogate indexes of IR were computed according to published formulas. IMT was measured by ultrasound method. Results The Stumvoll ISIOGTT index was correlated with IMT more strongly than the other indexes of IR. The IR indexes correlated significantly (P<0.0001) with all cardiovascular risk factors examined. The Stumvoll ISIOGTT index was correlated with waist circumference and high sensitivity C-reactive protein more strongly than the other indexes of IR. The area under the ROC curve (AUC), used to evaluate the accuracy of the IR indexes in identifying individuals with vascular damage defined as IMT >0.9 mm, for the Stumvoll ISIOGTT index was significantly higher (0.710) as compared with the AUCs of Matsuda (0.642) (P?=?0.0009), OGIS (0.666) (P?=?0.04), HOMA (0.611) (P<0.0001) and Liver IR (0.648) (P?=?0.0008) indexes. In a logistic regression model adjusted for age and gender, subjects in the lowest tertile of the Stumvoll ISIOGTT index had the highest risk of having vascular damage (OR 4.95, 95% CI 2.99–8.192) as compared to the corresponding tertiles of the other surrogate indexes. Conclusion The Stumvoll ISIOGTT index correlated more strongly than other validated surrogates indexes of IR with carotid IMT, and, therefore, it might be a significant indicator of vascular damage. PMID:23326550

  6. Clinical Forms of Vascular Dementia

    Microsoft Academic Search

    Gustavo C. Román

    The presence of vascular dementia (VaD) is largely unrecognized and untreated in the elderly (1,2). The typical history is that of an elderly parent or grandparent who fails to regain the previous level of function and\\u000a independence after a stroke. More often, in the absence of the heralding stroke symptoms, the family notices that the patient\\u000a has become depressed and

  7. Lymphatic Vascular System and Lymphangiogenesis

    Microsoft Academic Search

    Leah N. Cueni; Michael Detmar

    The lymphatic system plays an important role in the maintenance of tissue fluid homeostasis, in the afferent phase of the\\u000a immune response, and in metastatic cancer spread. However, the scientific exploration of the lymphatic system has lagged behind\\u000a that of the blood vascular system, largely due to the absence of specific markers for lymphatic endothelium and to the paucity\\u000a of

  8. The selectins: vascular adhesion molecules

    Microsoft Academic Search

    THOMAS F. TEDDER; DOUGLAS A. STEEBER; ANJUN CHEN; PABLO ENGEL

    1995-01-01

    The selectin family of adhesion mole- cules mediates the initial attachment of leukocytes to venular endothelial cells before their firm adhesion and diapedesis at sites of tissue injury and inflamma- tion. The selectin family consists of three closely related cell-surface molecules with differential ex- pression by leukocytes (L-selectin), platelets (P-se- lectin), and vascular endothelium (E- and P-selectin). The selectins have

  9. Computational Models of Vascular Mechanics

    Microsoft Academic Search

    Joseph R. Leach; Mohammad R. Kaazempur Mofrad; David Saloner

    \\u000a Many of the world’s leading causes of death involve pathology of the vasculature, both arterial and venous. In addition to\\u000a the biochemical and genetic factors governing vascular health and disease, mechanics strongly modulates the form and function\\u000a of the vessel wall. Biomechanical analysis is being increasingly used to not only elucidate key disease processes, but also\\u000a to predict disease progression

  10. Effect of water on hydrogen permeability

    NASA Technical Reports Server (NTRS)

    Hulligan, David; Tomazic, William A.

    1987-01-01

    Doping of hydrogen with CO and CO2 was developed to reduce hydrogen permeation in Stirling engines by forming a low permeability oxide coating on the inner surface of the heater head tubes. Although doping worked well, under certain circumstances the protective oxide could be chemically reduced by the hydrogen in the engine. Some oxygen is required in the hydrogen to prevent reduction. Eventually, all the oxygen in the hydrogen gas - whatever its source - shows up as water. This is the result of hydrogen reducing the CO, CO2, or the protective inner surface oxides. This water can condense in the engine system under the right conditions. If the concentration of water vapor is reduced to a low enough level, the hydrogen can chemically reduce the oxide coating, resulting in an increase in permeability. This work was done to define the minimum water content required to avoid this reduction in the oxide coating. The results of this testing show that a minimum of approximately 750 ppm water is required to prevent an increase in permeability of CG-27, a high temperature metal alloy selected for Stirling engine heater tubes.

  11. Nanoparticle uptake in tumors is mediated by the interplay of vascular and collagendensity with interstitial pressure

    PubMed Central

    Torosean, Sason; Flynn, Brendan; Axelsson, Johan; Gunn, Jason; Samkoe, Kimberley S.; Hasan, Tayyaba; Doyley, Marvin M.; Pogue, Brian W.

    2012-01-01

    Nanoparticle delivery into solid tumors is affected by vessel density, interstitial fluid pressure (IFP) and collagen, as shown here by contrasting the in vivo macroscopic quantitative uptake of 40 nm fluorescent beads in three tumor types. The fluorescence uptake was quantified on individual animals by normalization with the transmitted light and thennormalized to normal tissue uptake in each mouse. Mean data for uptake in individual tumor lines then showed expected trends with the largest uptake in the most vascularized tumor line. Tumor lines with increased collagen were also consistent with highest interstitial fluid pressure, and correlated with lowest uptake of nanoparticles. The data is consistent with a delivery model indicating that while vascular permeability is maximized by neovascular growth, it is inhibited by collagen content and the resulting interstitial pressure. Imaging of these parameters in vivo can lead to better individual non-invasive methods to assess drug penetration in situ. PMID:22841910

  12. Vascular Endothelial Growth Factor Levels in Dobrava/Belgrade Virus Infections

    PubMed Central

    Tsergouli, Katerina; Papa, Anna

    2013-01-01

    The levels of vascular endothelial growth factor-A (VEGF) were estimated in 102 serum samples from 63 hospitalized Greek patients with hemorrhagic fever with renal syndrome (HFRS) caused by Dobrava/Belgrade virus. Significantly higher VEGF levels were seen in the severe when compared with non-severe cases (mean values 851.96 pg/mL and 326.75 pg/mL, respectively; p = 0.003), while a significant difference was observed among groups based on the day after the onset of illness. In both severe and non-severe cases, VEGF peaked in the second week of illness; however, elevation of VEGF in the severe cases started later and remained high until convalescence, suggesting that the role of VEGF was associated with repair of vascular damage rather than with increased permeability. PMID:24335780

  13. TRPV channels and vascular function.

    PubMed

    Baylie, R L; Brayden, J E

    2011-09-01

    Transient receptor potential channels, of the vanilloid subtype (TRPV), act as sensory mediators, being activated by endogenous ligands, heat, mechanical and osmotic stress. Within the vasculature, TRPV channels are expressed in smooth muscle cells, endothelial cells, as well as in peri-vascular nerves. Their varied distribution and polymodal activation properties make them ideally suited to a role in modulating vascular function, perceiving and responding to local environmental changes. In endothelial cells, TRPV1 is activated by endocannabinoids, TRPV3 by dietary agonists and TRPV4 by shear stress, epoxyeicosatrienoic acids (EETs) and downstream of Gq-coupled receptor activation. Upon activation, these channels contribute to vasodilation via nitric oxide, prostacyclin and intermediate/small conductance potassium channel-dependent pathways. In smooth muscle, TRPV4 is activated by endothelial-derived EETs, leading to large conductance potassium channel activation and smooth muscle hyperpolarization. Conversely, smooth muscle TRPV2 channels contribute to global calcium entry and may aid constriction. TRPV1 and TRPV4 are expressed in sensory nerves and can cause vasodilation through calcitonin gene-related peptide and substance P release as well as mediating vascular function via the baroreceptor reflex (TRPV1) or via increasing sympathetic outflow during osmotic stress (TRPV4). Thus, TRPV channels play important roles in the regulation of normal and pathological cellular function in the vasculature. PMID:21062421

  14. Quantitative analysis of vascular calcification

    PubMed Central

    JOH, JIN HYUN; KIM, DONG IK

    2014-01-01

    Vascular calcification is a prominent feature of atherosclerosis. The mineral composition and quantity within calcified arterial plaques remains unelucidated; therefore, the aim of this study was to analyze the mineral composition of such plaques. Calcified arterial plaques were obtained from patients with abdominal aortic aneurysms (AAAs) and carotid artery stenoses. Calcified aneurysmal plaques were obtained during the routine open repair of AAAs, while calcified carotid plaques were collected from patients who underwent carotid endarterectomy (CEA). Following the appropriate preparation of each sample, inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to analyze the calcium and phosphate levels, while flame atomic absorption spectrometry (FAAS) was used to analyze the levels of iron and zinc. The levels of these mineral components were evaluated. In the aortic and carotid plaques, the mean calcium concentration was 9.83 and 11.94 wt.%, respectively, and the mean phosphate concentration was 4.31 and 6.08 wt.%, respectively. It was not possible to analyze the absolute concentration of iron in the carotid plaques due to the concentration being below the measurement limit. The zinc concentration was variable between samples. In conclusion, the main components of aortic and carotid plaques are calcium and phosphate. The mineral concentrations of the plaques in the present study may be used as reference values for further studies on vascular calcification. More studies are required to elucidate the correlation between the mineral components and vascular calcification. PMID:24348758

  15. Membrane stress increases cation permeability in red cells.

    PubMed Central

    Johnson, R M

    1994-01-01

    The human red cell is known to increase its cation permeability when deformed by mechanical forces. Light-scattering measurements were used to quantitate the cell deformation, as ellipticity under shear. Permeability to sodium and potassium was not proportional to the cell deformation. An ellipticity of 0.75 was required to increase the permeability of the membrane to cations, and flux thereafter increased rapidly as the limits of cell extension were reached. Induction of membrane curvature by chemical agents also did not increase cation permeability. These results indicate that membrane deformation per se does not increase permeability, and that membrane tension is the effector for increased cation permeability. This may be relevant to some cation permeabilities observed by patch clamping. Images FIGURE 4 PMID:7858123

  16. Missouri Botanical Garden: Catalogue of the Vascular Plants of Ecuador

    NSDL National Science Digital Library

    A collaborative project of the Missouri Botanical Garden, Pontificia Universidad Catolica del Ecuador, the Museo Ecuatoriano de Ciencias Naturales, and Aarhus University, this Internet version of the _Catalogue of the Vascular Plants of Ecuador_ "is designed to give users an overview of the plant species found in Ecuador and allows them to easily navigate and browse the information currently available." The _Catalogue_ "documents 15,901 plant species known to occur in Ecuador" and the site's Search Engine allows users to access data by scientific name or by using either the index to accepted names or the index to all names. This fantastic site also includes links to relevant information about Ecuador such as Geography, Paleoclimates, Vegetation, and History of Collecting. The website is available in Spanish as well as English.

  17. Renal transplant vascular complications: the role of Doppler ultrasound.

    PubMed

    Granata, Antonio; Clementi, Silvia; Londrino, Francesco; Romano, Giulia; Veroux, Massimiliano; Fiorini, Fulvio; Fatuzzo, Pasquale

    2015-06-01

    Improvements in the care of kidney transplant recipients and advances in immunosuppressive therapy have reduced the incidence of graft rejection. As a result, other types of kidney transplant complications, such as surgical, urologic, parenchymal, and vascular complications, have become more common. Although vascular complications account for only 5-10 % of all post-transplant complications, they are a frequent cause of graft loss. Ultrasonography, both in B-mode and with Doppler ultrasound, is a fundamental tool in the differential diagnosis of renal allograft dysfunction. Doppler ultrasound is highly specific in cases of transplanted renal artery stenosis, pseudoaneurysms, arteriovenous fistulas, and thrombosis with complete or partial artery or vein occlusion. A single measurements of color Doppler indexes display high diagnostic accuracy and in particular cases are more useful during the post-transplantation follow-up period. More recent techniques, such as contrast-enhanced ultrasound, undoubtedly increase the accuracy of ultrasonography in the diagnosis of vascular complications involving the transplanted kidney. PMID:26191097

  18. Body Mass Index and Risk of Parkinson's Disease: A Prospective Cohort Study

    Microsoft Academic Search

    Giancarlo Logroscino; Howard D. Sesso; Ralph S. Paffenbarger; I-Min Lee

    2007-01-01

    High body mass index has been associated with increased risk of several chronic diseases, including cardio- vascular disease, and, recently, Alzheimer's disease. There are few data on the association of body mass index with Parkinson's disease, and results have been inconsistent. The authors conducted a prospective study among 10,812 men in the Harvard Alumni Health Study, followed from 1988 to

  19. Vascular and Inflammatory Factors in the Pathophysiology of Blast-Induced Brain Injury

    PubMed Central

    Elder, Gregory A.; Gama Sosa, Miguel A.; De Gasperi, Rita; Stone, James Radford; Dickstein, Dara L.; Haghighi, Fatemeh; Hof, Patrick R.; Ahlers, Stephen T.

    2015-01-01

    Blast-related traumatic brain injury (TBI) has received much recent attention because of its frequency in the conflicts in Iraq and Afghanistan. This renewed interest has led to a rapid expansion of clinical and animal studies related to blast. In humans, high-level blast exposure is associated with a prominent hemorrhagic component. In animal models, blast exerts a variety of effects on the nervous system including vascular and inflammatory effects that can be seen with even low-level blast exposures which produce minimal or no neuronal pathology. Acutely, blast exposure in animals causes prominent vasospasm and decreased cerebral blood flow along with blood-brain barrier breakdown and increased vascular permeability. Besides direct effects on the central nervous system, evidence supports a role for a thoracically mediated effect of blast; whereby, pressure waves transmitted through the systemic circulation damage the brain. Chronically, a vascular pathology has been observed that is associated with alterations of the vascular extracellular matrix. Sustained microglial and astroglial reactions occur after blast exposure. Markers of a central and peripheral inflammatory response are found for sustained periods after blast injury and include elevation of inflammatory cytokines and other inflammatory mediators. At low levels of blast exposure, a microvascular pathology has been observed in the presence of an otherwise normal brain parenchyma, suggesting that the vasculature may be selectively vulnerable to blast injury. Chronic immune activation in brain following vascular injury may lead to neurobehavioral changes in the absence of direct neuronal pathology. Strategies aimed at preventing or reversing vascular damage or modulating the immune response may improve the chronic neuropsychiatric symptoms associated with blast-related TBI. PMID:25852632

  20. Expression of vascular endothelial growth factor mRNA in non-small-cell lung carcinomas

    PubMed Central

    Fontanini, G; Boldrini, L; Chinè, S; Pisaturo, F; Basolo, F; Calcinai, A; Lucchi, M; Mussi, A; Angeletti, C A; Bevilacqua, G

    1999-01-01

    The vascular endothelial growth factor (VEGF) has been shown to be strictly related to vascular permeability and endothelial cell growth under physiological and pathological conditions. In tumour development and progression, VEGF plays a pivotal role in the development of the tumoral vascular network, and useful information in the progression of human cancer can be obtained by analysing the vascular endothelial growth factor expression of the tumours. In this study, we investigated the vascular endothelial growth factor transcript expression in non-small-cell lung carcinomas to evaluate the significance of this factor in a group of cancers in which the vascular pattern has been shown to significantly affect progression. Surgical samples of 42 patients with NSCLC were studied using reverse transcription polymerase chain reaction (PCR) analysis and in situ hybridization. Thirty-three out of 42 cases (78.6%) showed VEGF transcript expression predominantly as transcripts for the secretory forms of VEGF (isoforms 121 and 165). In situ hybridization, performed on 24 out of 42 samples, showed that the VEGF transcript expression was in several cases present in the cytoplasm both of neoplastic and normal cells, even if the VEGF mRNA was less expressed in the corresponding non-tumoral part. The VEGF 121 expression was associated with hilar and/or mediastinal nodal involvement (P = 0.02), and, taken together, the VEGF isoforms were shown to significantly influence overall (P = 0.02) and disease-free survival (P = 0.03). As a regulator of tumour angiogenesis, VEGF may represent a useful indicator of progression and poor prognosis in non-small-cell lung carcinomas. © 1999 Cancer Research Campaign PMID:9888482

  1. Expression of vascular endothelial growth factor mRNA in non-small-cell lung carcinomas.

    PubMed

    Fontanini, G; Boldrini, L; Chinè, S; Pisaturo, F; Basolo, F; Calcinai, A; Lucchi, M; Mussi, A; Angeletti, C A; Bevilacqua, G

    1999-01-01

    The vascular endothelial growth factor (VEGF) has been shown to be strictly related to vascular permeability and endothelial cell growth under physiological and pathological conditions. In tumour development and progression, VEGF plays a pivotal role in the development of the tumoral vascular network, and useful information in the progression of human cancer can be obtained by analysing the vascular endothelial growth factor expression of the tumours. In this study, we investigated the vascular endothelial growth factor transcript expression in non-small-cell lung carcinomas to evaluate the significance of this factor in a group of cancers in which the vascular pattern has been shown to significantly affect progression. Surgical samples of 42 patients with NSCLC were studied using reverse transcription polymerase chain reaction (PCR) analysis and in situ hybridization. Thirty-three out of 42 cases (78.6%) showed VEGF transcript expression predominantly as transcripts for the secretory forms of VEGF (isoforms 121 and 165). In situ hybridization, performed on 24 out of 42 samples, showed that the VEGF transcript expression was in several cases present in the cytoplasm both of neoplastic and normal cells, even if the VEGF mRNA was less expressed in the corresponding non-tumoral part. The VEGF 121 expression was associated with hilar and/or mediastinal nodal involvement (P = 0.02), and, taken together, the VEGF isoforms were shown to significantly influence overall (P = 0.02) and disease-free survival (P = 0.03). As a regulator of tumour angiogenesis, VEGF may represent a useful indicator of progression and poor prognosis in non-small-cell lung carcinomas. PMID:9888482

  2. Early Adaptive Responses of the Vascular Wall during Venous Arterialization in Mice

    PubMed Central

    Kwei, Stephanie; Stavrakis, George; Takahas, Masaya; Taylor, George; Folkman, M. Judah; Gimbrone, Michael A.; García-Cardeña, Guillermo

    2004-01-01

    Venous arterialization occurs when a vein segment is transposed as a bypass graft into the arterial circulation, resulting in a structural and functional reorganization of the vascular wall in response to the new local biomechanical environment. Although the anatomical changes of venous arterialization have been well characterized, the molecular mechanisms of vascular remodeling remain incompletely understood. Here, we present a novel model of venous arterialization in mice wherein the external jugular vein is connected to the common carotid artery. The hemodynamic characteristics of the arterialized vein, as assessed by ultrasound and magnetic resonance imaging, resemble features of the arterial circulation. Temporal analyses of the morphological changes in the venous segment at 1, 3, and 7 days after surgery demonstrate preservation of the endothelium at all time points and formation of multiple smooth muscle layers by day 7. Expression of endothelial E-selectin and VCAM-1 was documented at early time points, concomitant with the presence of neutrophils and monocytes/macrophages in the vascular wall. In addition, endothelium-dependent permeability was decreased in the arterialized vein when compared to the contralateral control vein. Thus, this novel mouse model of venous arterialization displays anatomical and cellular features present in other species, and should help to characterize the molecular mechanisms of this adaptive response of the vascular wall to changes in its biomechanical environment. PMID:14695322

  3. development index (HDI)

    E-print Network

    HDI rank a Human development index (HDI) value Life expectancy at birth (years) Adult literacy rate per capita (PPP US$) Life expectancy index Education index GDP index GDP per capita (PPP US$) rank development index (HDI) value Life expectancy at birth (years) Adult literacy rate (% aged 15 and above) Com

  4. Epithelial and mesenchymal tumor compartments exhibit in vivo complementary patterns of vascular perfusion and glucose metabolism.

    PubMed

    Galiè, Mirco; Farace, Paolo; Nanni, Cristina; Spinelli, Antonello; Nicolato, Elena; Boschi, Federico; Magnani, Paolo; Trespidi, Silvia; Ambrosini, Valentina; Fanti, Stefano; Merigo, Flavia; Osculati, Francesco; Marzola, Pasquina; Sbarbati, Andrea

    2007-11-01

    Glucose transport and consumption are increased in tumors, and this is considered a diagnostic index of malignancy. However, there is recent evidence that carcinoma-associated stromal cells are capable of aerobic metabolism with low glucose consumption, at least partly because of their efficient vascular supply. In the present study, using dynamic contrast-enhanced magnetic resonance imaging and [F-18]fluorodeoxyglucose (FDG) positron emission tomography (PET), we mapped in vivo the vascular supply and glucose metabolism in syngeneic experimental models of carcinoma and mesenchymal tumor. We found that in both tumor histotypes, regions with high vascular perfusion exhibited a significantly lower FDG uptake. This reciprocity was more conspicuous in carcinomas than in mesenchymal tumors, and regions with a high-vascular/low-FDG uptake pattern roughly overlapped with a stromal capsule and intratumoral large connectival septa. Accordingly, mesenchymal tumors exhibited a higher vascular perfusion and a lower FDG uptake than carcinomas. Thus, we provide in vivo evidence of vascular/metabolic reciprocity between epithelial and mesenchymal histotypes in tumors, suggesting a new intriguing aspect of epithelial-stromal interaction. Our results suggests that FDG-PET-based clinical analysis can underestimate the malignity or tumor extension of carcinomas exhibiting any trait of "mesenchymalization" such as desmoplasia or epithelial-mesenchymal transition. PMID:18030358

  5. Permeability of concrete containing large amounts of fly ash

    SciTech Connect

    Naik, T.R.; Singh, S.S.; Hossain, M.M. (Univ. of Wisconsin, Milwaukee, WI (United States). Dept. of Civil Engineering and Mechanics)

    1994-01-01

    This study was carried out to evaluate the influence of addition of a Class C fly ash on concrete permeability. An air entrained reference concrete mixture without fly ash was proportioned to have a 28-day strength of 41 MPa. Concrete mixtures were also proportioned to have cement replacement with fly ash in the range of 0--70% by weight. For each concrete mixture, compressive strength, chloride permeability, air permeability, and water permeability were determined. Air and water permeability were evaluated by using the Figg method. Chloride permeability of the concrete was measured in accordance with the ASTM C 1202. At ages up to 28-day, no-fly ash concrete attained lower air permeability compared to high-volume fly ash concretes. At 91 days, the mixture having 50% cement replacement exhibited the lowest air permeability. The same was true for water permeability also. In general, addition of fly ash caused a decrease in chloride permeability of concrete up to 50% cement replacement.

  6. EPA/ITRC-RTDF permeable reactive barrier short course. Permeable reactive barriers: Application and deployment

    SciTech Connect

    NONE

    1999-11-01

    This report focuses on the following: Permeable Reactive Barriers: Application and Deployment; Introduction to Permeable Reactive Barriers (PRBs) for Remediating and Managing Contaminated Groundwater in Situ; Collection and Interpretation of Design Data 1: Site Characterization for PRBs; Reactive Materials: Zero-Valent Iron; Collection and Interpretation of Design Data 2: Laboratory and Pilot Scale Tests; Design Calculations; Compliance Monitoring, Performance Monitoring and Long-Term Maintenance for PRBs; PRB Emplacement Techniques; PRB Permitting and Implementation; Treatment of Metals; Non-Metallic Reactive Materials; Economic Considerations for PRB Deployment; and Bibliography.

  7. EPA/ITRC-RTDF permeable reactive barrier short course. Permeable reactive barriers: Application and deployment

    SciTech Connect

    Not Available

    1999-01-01

    This report focuses on the following: Permeable Reactive Barriers: Application and Deployment; Introduction to Permeable Reactive Barriers (PRBs) for Remediating and Managing Contaminated Groundwater in Situ; Collection and Interpretation of Design Data 1: Site Characterization for PRBs; Reactive Materials: Zero-Valent Iron; Collection and Interpretation of Design Data 2: Laboratory and Pilot Scale Tests; Design Calculations; Compliance Monitoring, Performance Monitoring and Long-Term Maintenance for PRBs; PRB Emplacement Techniques; PRB Permitting and Implementation; Treatment of Metals; Non-Metallic Reactive Materials; Economic Considerations for PRB Deployment; and Bibliography.

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

    PubMed Central

    2013-01-01

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

  9. Low-loss spinel nanoferrite with matching permeability and permittivity in the ultrahigh frequency range

    Microsoft Academic Search

    A. Thakur; A. Chevalier; J.-L. Mattei; P. Queffe´lec

    2010-01-01

    Ferrite nanoparticles with a composition of Ni0.5Zn0.3Co0.2Fe2O4 were prepared by a coprecipitation method. The sample obtained after treating at appropriating conditions had almost equal real permeability and permittivity, of 4.8+j0.15 (loss tangent?0.04) and 4.9+j0.10 (loss tangent?0.018), respectively, over 100 to 500 MHz. This material had a refractive index n of close to 5 and a reduced impedance Z\\/Z0 of close

  10. Neutrophil Depletion Suppresses Pulmonary Vascular Hyperpermeability and Occurrence of Pulmonary Edema Caused by Hantavirus Infection in C.B-17 SCID Mice

    PubMed Central

    Koma, Takaaki; Yoshimatsu, Kumiko; Nagata, Noriyo; Sato, Yuko; Shimizu, Kenta; Yasuda, Shumpei P.; Amada, Takako; Nishio, Sanae; Hasegawa, Hideki

    2014-01-01

    ABSTRACT Hantavirus infections are characterized by vascular hyperpermeability and neutrophilia. However, the pathogenesis of this disease is poorly understood. Here, we demonstrate for the first time that pulmonary vascular permeability is increased by Hantaan virus infection and results in the development of pulmonary edema in C.B-17 severe combined immunodeficiency (SCID) mice lacking functional T cells and B cells. Increases in neutrophils in the lung and blood were observed when pulmonary edema began to be observed in the infected SCID mice. The occurrence of pulmonary edema was inhibited by neutrophil depletion. Moreover, the pulmonary vascular permeability was also significantly suppressed by neutrophil depletion in the infected mice. Taken together, the results suggest that neutrophils play an important role in pulmonary vascular hyperpermeability and the occurrence of pulmonary edema after hantavirus infection in SCID mice. IMPORTANCE Although hantavirus infections are characterized by the occurrence of pulmonary edema, the pathogenic mechanism remains largely unknown. In this study, we demonstrated for the first time in vivo that hantavirus infection increases pulmonary vascular permeability and results in the development of pulmonary edema in SCID mice. This novel mouse model for human hantavirus infection will be a valuable tool and will contribute to elucidation of the pathogenetic mechanisms. Although the involvement of neutrophils in the pathogenesis of hantavirus infection has largely been ignored, the results of this study using the mouse model suggest that neutrophils are involved in the vascular hyperpermeability and development of pulmonary edema in hantavirus infection. Further study of the mechanisms could lead to the development of specific treatment for hantavirus infection. PMID:24719427

  11. Relation between non-uniform hemodynamics and sites of altered permeability and lesion growth at the rabbit aorto-celiac junction

    Microsoft Academic Search

    John R. Buchanan; Clement Kleinstreuer; George A. Truskey; Ming Lei

    1999-01-01

    Using the rabbit’s aorto-celiac junction as a representative atherosclerotic model, the hemodynamics of a bifurcating blood vessel are numerically simulated and three hemodynamic parameters are compared. The wall shear stress (WSS), the oscillatory shear index (OSI), and the spatial wall shear stress gradient (WSSG) are considered in this study. Locally enhanced wall permeabilities and intimal macrophages are generally considered to

  12. Megakaryocytes, Malignancy and Bone Marrow Vascular Niches

    PubMed Central

    Psaila, Bethan; Lyden, David; Roberts, Irene

    2011-01-01

    Summary Dynamic interactions between haematopoietic cells and their specialised bone marrow microenvironments, namely the vascular and osteoblastic ‘niches’ regulate haematopoiesis. The vascular niche is conducive for thrombopoiesis, and megakaryocytes may, in turn, regulate the vascular niche, especially in supporting vascular and haematopoietic regeneration following irradiation or chemotherapy. A role for platelets in tumour growth and metastasis is well established and, more recently, the vascular niche has also been implicated as an area for preferential homing and engraftment of malignant cells. This article aims to provide an overview of the dynamic interactions between cellular and molecular components of the bone marrow vascular niche and the potential role of megakaryocytes in bone marrow malignancy. PMID:22122829

  13. Eph-A2 Promotes Permeability and Inflammatory Responses to Bleomycin-Induced Lung Injury

    PubMed Central

    Schroeder, William; Stenmark, Kurt R.; Schmidt, Eric P.

    2012-01-01

    Stimulation by the ephrin-A1 ligand of the EphA2 receptor increases endothelial permeability. Lung injury increases the expression of EphA2, but the role of EphA2 in such injury is not well understood. To determine whether EphA2 contributes to changes in permeability and inflammation in the injured lung, we studied wild-type (WT) and EphA2 knockout (KO) mice, using isolated, perfused lung (IPL) preparations and a model of bleomycin-induced lung injury. We also studied the response of endothelial cells to ephrin-A1. In the IPL preparations, ephrin-A1 increased the filtration coefficient in WT mice, but not in EphA2 KO mice, demonstrating that EphA2 regulates vascular permeability. In early bleomycin injury in WT mice, the expression of both EphA2 and ephrin-A1 increased. EphA2 KO animals were protected from lung injury, showing less water and alveolar protein in the lungs than WT mice, consistent with reduced permeability. Bleomycin caused less accumulation of lung leukocytes in EphA2 KO animals than in WT animals, suggesting that EphA2 regulates inflammation. To determine whether EphA2 deficiency alters the production of chemokines, CXCL1 and CCL2 in the lungs were measured. After bleomycin injury, EphA2 KO animals produced less CXCL1 and CCL2 than WT animals. Because NF-?? mediates the production of chemokines, the effect of the ephrin-A1 ligand on the activation of NF-?? and the expression of chemokines was measured in endothelial cells. Ephrin-a1 significantly increased NF-?? nuclear translocation and the expression of chemokine mRNA. This study demonstrates that the expression of EphA2 increases in the injured lung, and not only contributes to changes in permeability, but also plays a previously unrecognized role in promoting inflammatory responses. PMID:21799118

  14. Bradykinin and changes in microvascular permeability in the hamster cheek pouch: role of nitric oxide.

    PubMed

    Félétou, M; Bonnardel, E; Canet, E

    1996-07-01

    1. The objective of this study in the hamster cheek pouch was to investigate the role of nitric oxide in bradykinin-induced microvascular leakage. The cheek pouch microcirculatory bed of the anaesthetized hamster was directly observed under microscope and vascular leakage was evidenced by dextranfluorescein isothiocyanate (FITC-dextran) extravasation. 2. Bradykinin superfusion (but not [des-Arg9]-bradykinin up to 3 x 10(-6) M) induced an increase in microvascular permeability (log EC50: -6.5 +/- 0.4) which was exclusively located on the post-capillary venule. Plasma extravasation was blocked by intravenous pretreatment with Hoe 140, a bradykinin B2 receptor antagonist (estimated log ID50: -9.5 +/- 0.2). 3. The effects of bradykinin (3 x 10(-7) M) superfusion were partially but significantly inhibited by indomethacin (10(-5) M, P < 0.05) and abolished by pretreatment with L-nitro-arginine (L-NOARG; 10(-5) M). 4. Acetylcholine (10(-6) M, which releases endothelial nitric oxide (NO), and sodium nitroprusside (10(-6) M, a nitrovasodilator) superfusion did not induce any changes in permeability, per se. Cromakalim (10(-5) M, a potassium channel opener) superfusion induced a moderate but significant plasma extravasation. 5. The effects of bradykinin, blocked by L-NOARG pretreatment, were restored by the co-perfusion of either sodium nitroprusside or cromakalim. Conversely vasoconstriction, produced by a stable analogue of thromboxane A2 (U46619, 3 x 10(-7) M), inhibited the increase in permeability produced by bradykinin. 6. The measurement of arteriolar diameter showed that bradykinin induced a vasodilatation which was blocked by L-NOARG. L-NOARG in itself was a powerful vasoconstrictor. Sodium nitroprusside and cromakalim, in the presence of L-NOARG, were able to restore the inhibited vasodilator response to bradykinin. 7. These results suggest: (1) bradykinin-induced microvascular leakage is mediated by bradykinin B2 receptor activation; (2) the increase in permeability is due to two different independent phenomena, i.e. post-capillary venular endothelial gap formation and arteriolar vasodilatation which increases the post-capillary venular transmural pressure: (3) NO is only involved in the arteriolar dilatation component of the bradykinin-induced increase in microvascular permeability. PMID:8832059

  15. Bradykinin and changes in microvascular permeability in the hamster cheek pouch: role of nitric oxide.

    PubMed Central

    Félétou, M.; Bonnardel, E.; Canet, E.

    1996-01-01

    1. The objective of this study in the hamster cheek pouch was to investigate the role of nitric oxide in bradykinin-induced microvascular leakage. The cheek pouch microcirculatory bed of the anaesthetized hamster was directly observed under microscope and vascular leakage was evidenced by dextranfluorescein isothiocyanate (FITC-dextran) extravasation. 2. Bradykinin superfusion (but not [des-Arg9]-bradykinin up to 3 x 10(-6) M) induced an increase in microvascular permeability (log EC50: -6.5 +/- 0.4) which was exclusively located on the post-capillary venule. Plasma extravasation was blocked by intravenous pretreatment with Hoe 140, a bradykinin B2 receptor antagonist (estimated log ID50: -9.5 +/- 0.2). 3. The effects of bradykinin (3 x 10(-7) M) superfusion were partially but significantly inhibited by indomethacin (10(-5) M, P < 0.05) and abolished by pretreatment with L-nitro-arginine (L-NOARG; 10(-5) M). 4. Acetylcholine (10(-6) M, which releases endothelial nitric oxide (NO), and sodium nitroprusside (10(-6) M, a nitrovasodilator) superfusion did not induce any changes in permeability, per se. Cromakalim (10(-5) M, a potassium channel opener) superfusion induced a moderate but significant plasma extravasation. 5. The effects of bradykinin, blocked by L-NOARG pretreatment, were restored by the co-perfusion of either sodium nitroprusside or cromakalim. Conversely vasoconstriction, produced by a stable analogue of thromboxane A2 (U46619, 3 x 10(-7) M), inhibited the increase in permeability produced by bradykinin. 6. The measurement of arteriolar diameter showed that bradykinin induced a vasodilatation which was blocked by L-NOARG. L-NOARG in itself was a powerful vasoconstrictor. Sodium nitroprusside and cromakalim, in the presence of L-NOARG, were able to restore the inhibited vasodilator response to bradykinin. 7. These results suggest: (1) bradykinin-induced microvascular leakage is mediated by bradykinin B2 receptor activation; (2) the increase in permeability is due to two different independent phenomena, i.e. post-capillary venular endothelial gap formation and arteriolar vasodilatation which increases the post-capillary venular transmural pressure: (3) NO is only involved in the arteriolar dilatation component of the bradykinin-induced increase in microvascular permeability. PMID:8832059

  16. Applications of the Amplatzer Vascular Plug to various vascular lesions

    PubMed Central

    Güneyli, Serkan; Ç?nar, Celal; Bozkaya, Halil; Par?ldar, Mustafa; Oran, ?smail

    2014-01-01

    The Amplatzer® Vascular Plug (AVP) can be used to embolize medium-to-large high-flow vessels in various locations. Between 2009 and 2012, 41 AVPs (device size, 6–22 mm in diameter) were used to achieve occlusion in 31 patients (24 males, seven females) aged 9–92 years (mean age, 54.5 years). The locations and indications for embolotherapy were as follows: internal iliac artery embolization before stent-graft repair for aorto-iliac (n=6) and common iliac artery (n=3) aneurysms, subclavian artery embolization before stent-graft repair for thoracic aorta (n=3) and arcus aorta (n=1) aneurysms, brachiocephalic trunk embolization before stent-graft repair for a thoracic aorta aneurysm (n=1), embolization of aneurysms and pseudoaneurysms (n=5), embolization for carotid blow-out syndrome (n=3), closure of arteriovenous fistula (n=8), and closure of a portosystemic fistula (n=1). Of the 41 AVPs, 30 were AVP 2 and 11 were AVP 4. The mean follow-up duration was 4.7 months (range, 1–24 months). During follow-up, there was one migration, one insufficient embolization, and one recanalization. The remaining vascular lesions were successfully excluded from the circulation. The AVP, which can be used in a wide spectrum of pathologies, is easy to use and causes few complications. This essay presents our experience with the AVP. PMID:24047719

  17. Migraine and Stroke: “Vascular” Comorbidity

    PubMed Central

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

    2014-01-01

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

  18. Tissue engineering of small caliber vascular grafts

    Microsoft Academic Search

    Simon P Hoerstrup; Gregor Zünd; Ralf Sodian; Andrea M Schnell; Jürg Grünenfelder; Marko I Turina

    2001-01-01

    Objective: Previous tissue engineering approaches to create small caliber vascular grafts have been limited by the structural and mechanical immaturity of the constructs. This study uses a novel in vitro pulse duplicator system providing a ‘biomimetic’ environment during tissue formation to yield more mature, implantable vascular grafts. Methods: Vascular grafts (I.D. 0.5 cm) were fabricated from novel bioabsorbable polymers (polyglycolic-acid\\/poly-4-hydroxybutyrate)

  19. Vascular ring complicates accidental button battery ingestion.

    PubMed

    Mercer, Ronald W; Schwartz, Matthew C; Stephany, Joshua; Donnelly, Lane F; Franciosi, James P; Epelman, Monica

    2015-01-01

    Button battery ingestion can lead to dangerous complications, including vasculoesophageal fistula formation. The presence of a vascular ring may complicate battery ingestion if the battery lodges at the level of the ring and its important vascular structures. We report a 4-year-old boy with trisomy 21 who was diagnosed with a vascular ring at the time of button battery ingestion and died 9 days after presentation due to massive upper gastrointestinal bleeding from esophageal erosion and vasculoesophageal fistula formation. PMID:25662210

  20. Inhibition of Vascularization in Tumor Growth

    NASA Astrophysics Data System (ADS)

    Scalerandi, M.; Sansone, B. Capogrosso

    2002-11-01

    The transition to a vascular phase is a prerequisite for fast tumor growth. During the avascular phase, the neoplasm feeds only from the (relatively few) existing nearby blood vessels. During angiogenesis, the number of capillaries surrounding and infiltrating the tumor increases dramatically. A model which includes physical and biological mechanisms of the interactions between the tumor and vascular growth describes the avascular-vascular transition. Numerical results agree with clinical observations and predict the influence of therapies aiming to inhibit the transition.

  1. Cryptic vascular malformations involving the brainstem

    SciTech Connect

    Yeates, A.; Enzmann, D.

    1983-01-01

    Six patients with angiographically cryptic vascular malformations involving the brainstem were examined with computed tomography (CT). The clinical and CT findings of cryptic vascular malformations of the brainstem are described and distinguished from those of brainstem glioma and multiple sclerosis. Calcification within a brainstem lesion that displays relatively little mass effect and shows little contrast enhancement, particularly when associated with a long history of waxing and waning brainstem symptoms, should suggest a vascular malformation.

  2. [Congenital vascular malformations (Hauert disease)].

    PubMed

    Hauert, J; Loose, D A; Dreyer, T; Obermayer, B; Deibele, A

    2012-06-01

    Patients with congenital vascular malformations often suffer from arthralgia, especially of the lower limbs. This orthopaedic disease pattern is defined as destructive, angiodysplatic arthritis or Hauert disease and leads to very early destruction of the joints. By presenting diagnostic and therapeutic algorithms, Hauert disease is emphasized as a possible differential diagnosis in order to minimize the risk of an incorrect diagnosis which might lead to under-, over-, or even incorrect treatment. A minimally invasive transathroscopic therapy in the early stages can lead to significant improvement of symptoms and prevention of progressive joint destruction. PMID:22699760

  3. Evaluation of permeable fractures in rock aquifers

    NASA Astrophysics Data System (ADS)

    Bok Lee, Hang

    2015-04-01

    In this study, the practical usefulness and fundamental applicability of a self-potential (SP) method for identifying the permeable fractures were evaluated by a comparison of SP methods with other geophysical logging methods and hydraulic tests. At a 10 m-shallow borehole in the study site, the candidates of permeable fractures crossing the borehole were first determined by conventional geophysical methods such as an acoustic borehole televiwer, temperature, electrical conductivity and gamma-gamma loggings, which was compared to the analysis by the SP method. Constant pressure injection and recovery tests were conducted for verification of the hydraulic properties of the fractures identified by various logging methods. The acoustic borehole televiwer and gamma-gamma loggings detected the open space or weathering zone within the borehole, but they cannot prove the possibility of a groundwater flow through the detected fractures. The temperature and electrical conductivity loggings had limitations to detect the fractured zones where groundwater in the borehole flows out to the surrounding rock aquifers. Comparison of results from different methods showed that there is a best correlation between the distribution of hydraulic conductivity and the variation of the SP signals, and the SP logging can estimate accurately the hydraulic activity as well as the location of permeable fractures. Based on the results, the SP method is recommended for determining the hydraulically-active fractures rather than other conventional geophysical loggings. This self-potential method can be effectively applied in the initial stage of a site investigation which selects the optimal location and evaluates the hydrogeological property of fractures in target sites for the underground structure including the geothermal reservoir and radioactive waste disposal.

  4. Clamshell excavation of a permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Molfetta, Antonio Di; Sethi, Rajandrea

    2006-06-01

    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 Barriers Team 2005). Although, a variety of excavation methods have been developed, backhoe excavators are often used for the construction of PRBs. The aim of this study is to describe the emplacement of a full-scale PRB and the benefits deriving from the use of a crawler crane equipped with a hydraulic grab (also known as clamshell excavator) in the excavation phases. The studied PRB was designed to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in Italy. The continuous reactive barrier was designed to be 120 m long, 13 m deep, and 0.6 m thick. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 7 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. Moreover, the adopted technique permitted a saving of bioslurry thus minimizing the amount of biocide required.

  5. Engineered Trehalose Permeable to Mammalian Cells

    PubMed Central

    Abazari, Alireza; Meimetis, Labros G.; Budin, Ghyslain; Bale, Shyam Sundhar; Weissleder, Ralph; Toner, Mehmet

    2015-01-01

    Trehalose is a naturally occurring disaccharide which is associated with extraordinary stress-tolerance capacity in certain species of unicellular and multicellular organisms. In mammalian cells, presence of intra- and extracellular trehalose has been shown to confer improved tolerance against freezing and desiccation. Since mammalian cells do not synthesize nor import trehalose, the development of novel methods for efficient intracellular delivery of trehalose has been an ongoing investigation. Herein, we studied the membrane permeability of engineered lipophilic derivatives of trehalose. Trehalose conjugated with 6 acetyl groups (trehalose hexaacetate or 6-O-Ac-Tre) demonstrated superior permeability in rat hepatocytes compared with regular trehalose, trehalose diacetate (2-O-Ac-Tre) and trehalose tetraacetate (4-O-Ac-Tre). Once in the cell, intracellular esterases hydrolyzed the 6-O-Ac-Tre molecules, releasing free trehalose into the cytoplasm. The total concentration of intracellular trehalose (plus acetylated variants) reached as high as 10 fold the extracellular concentration of 6-O-Ac-Tre, attaining concentrations suitable for applications in biopreservation. To describe this accumulation phenomenon, a diffusion-reaction model was proposed and the permeability and reaction kinetics of 6-O-Ac-Tre were determined by fitting to experimental data. Further studies suggested that the impact of the loading and the presence of intracellular trehalose on cellular viability and function were negligible. Engineering of trehalose chemical structure rather than manipulating the cell, is an innocuous, cell-friendly method for trehalose delivery, with demonstrated potential for trehalose loading in different types of cells and cell lines, and can facilitate the wide-spread application of trehalose as an intracellular protective agent in biopreservation studies. PMID:26115179

  6. What about temperature? Measuring permeability at magmatic conditions.

    NASA Astrophysics Data System (ADS)

    Kushnir, Alexandra R. L.; Martel, Caroline; Champallier, Rémi; Reuschlé, Thierry

    2015-04-01

    The explosive potential of volcanoes is intimately linked to permeability, which is governed by the connectivity of the porous structure of the magma and surrounding edifice. As magma ascends, volatiles exsolve from the melt and expand, creating a gas phase within the conduit. In the absence of a permeable structure capable of dissipating these gases, the propulsive force of an explosive eruption arises from the gas expansion and the build up of subsurface overpressures. Thus, characterizing the permeability of volcanic rocks under in-situ conditions (high temperature and pressure) allows us to better understand the outgassing potential and explosivity of volcanic systems. Current studies of the permeabilities of volcanic rocks generally measure permeability at room temperature using gas permeameters or model permeability using analytic imaging. Our goal is to perform and assess permeability measurements made at high temperature and high pressure in the interest of approaching the permeability of the samples at magmatic conditions. We measure the permeability of andesitic samples expelled during the 2010 Mt. Merapi eruption. We employ and compare two protocols for measuring permeability at high temperature and under high pressure using argon gas in an internally heated Paterson apparatus with an isolated pore fluid system. We first use the pulse decay method to measure the permeability of our samples, then compare these values to permeability measurements performed under steady state flow. We consider the steady state flow method the more rigorous of the two protocols, as we are more capable of accounting for the temperature gradient within the entire pore fluid system. At temperatures in excess of 700°C and pressures of 100 MPa, permeability values plummet by several orders of magnitude. These values are significantly lower than those commonly reported for room temperature permeameter measurements. The reduction in permeability at high temperature is a combination of pressure and possible viscous healing. Importantly, at temperatures above the glass transition temperature (the temperature above which the glass within the sample begins to behave viscously) the permeable structure of the sample becomes increasingly transient. This changeable structure, as well as the technical nuances of high pressure-temperature measurements makes the measurement and interpretation of permeability at high temperatures challenging. Indeed, a re-evaluation of the use of the term 'permeability' when discussing magmas is necessary.

  7. Vascular nursing in Greece: luxury or necessity?

    PubMed

    Georgakarakos, Efstratios; Bitza, Christina; Papanas, Nikolaos; Matsagkas, Miltiadis; Lazarides, Miltos K

    2013-09-01

    Although peripheral arterial disease is prevalent in the primary care setting, insufficient vascular education among nurses and physicians coupled with certain economic constraints undermines treatment efficacy. Moreover, the burden of advanced venous pathology such as posthrombotic syndrome, venous ulcers, and lymphedema remains suboptimally treated. This article advocates the development of a vascular nursing specialty as a means to improving vascular care especially nowadays, when health care providers dictate comprehensive and cost-effective nursing practice and patient management. It also presents the first attempt to organize a Vascular Nursing Educational Session in Greece. PMID:24043676

  8. Scaffolds in vascular regeneration: current status

    PubMed Central

    Thottappillil, Neelima; Nair, Prabha D

    2015-01-01

    An ideal vascular substitute, especially in <6 mm diameter applications, is a major clinical essentiality in blood vessel replacement surgery. Blood vessels are structurally complex and functionally dynamic tissue, with minimal regeneration potential. These have composite extracellular matrix (ECM) and arrangement. The interplay between ECM components and tissue specific cells gives blood vessels their specialized functional attributes. The core of vascular tissue engineering and regeneration relies on the challenges in creating vascular conduits that match native vessels and adequately regenerate in vivo. Out of numerous vascular regeneration concerns, the relevance of ECM emphasizes much attention toward appropriate choice of scaffold material and further scaffold development strategies. The review is intended to be focused on the various approaches of scaffold materials currently in use in vascular regeneration and current state of the art. Scaffold of choice in vascular tissue engineering ranges from natural to synthetic, decellularized, and even scaffold free approach. The applicability of tubular scaffold for in vivo vascular regeneration is under active investigation. A patent conduit with an ample endothelial luminal layer that can regenerate in vivo remains an unanswered query in the field of small diameter vascular tissue engineering. Besides, scaffolds developed for vascular regeneration, should aim at providing functional substitutes for use in a regenerative approach from the laboratory bench to patient bedside. PMID:25632236

  9. Vascular grafting strategies in coronary intervention

    NASA Astrophysics Data System (ADS)

    Knight, Darryl; Gillies, Elizabeth; Mequanint, Kibret

    2014-06-01

    With the growing need for coronary revascularizations globally, several strategies to restore blood flow to the heart have been explored. Bypassing the atherosclerotic coronary arteries with autologous grafts, synthetic prostheses and tissue-engineered vascular grafts continue to be evaluated in search of a readily available vascular graft with clinically acceptable outcomes. The development of such a vascular graft including tissue engineering approaches both in situ and in vitro is herein reviewed, facilitating a detailed comparison on the role of seeded cells in vascular graft patency.

  10. [Weightlessness or weightlessness simulation and vascular remodeling].

    PubMed

    Yue, Yong; Yao, Yong-jie; Sun, Xi-qing; Wu, Xing-yu

    2003-04-01

    Weightlessness is inavoidable during spaceflight. It brings profound physiological effects on human body. Vascular remodeling is one of the important changes of cardiovascular system caused by weightlessness or simulated weightlessness. The paper summarized the studies on the effects of weightlessness or weightlessness simulation on vascular remodeling in recent years. The emergence and development of the concept of vascular remodeling were briefly reviewed. The advances of study on vascular remodeling in recent years was briefly discussed with the points focused on the effects of weightlessness or weightlessness simulation on cardiovascular remodeling and its mechanism. It is proposed that cardiovascular remodeling might be important in studying the causes of orthostatic intolerance after spaceflight. PMID:12830841

  11. [Diagnosis and management of vascular anomalies].

    PubMed

    Philandrianos, C; Degardin, N; Casanova, D; Petit, P; Bartoli, J-M; Bardot, J; Magalon, G

    2011-06-01

    Vascular anomalies are a complex pathological group. They are especially difficult to study because of confusion in the terminology used. The classification developed by the International Society for the Study of Vascular Anomalies (ISSVA) in 1996 allows using a common scientific language. There are two groups of lesions: vascular tumor and vascular malformation. The management of these anomalies is difficult and must involve an interdisciplinary approach including specialists in plastic surgery, radiology, pediatry and dermatology. We propose a simplified approach for the management of these pathologies. This approach is coming from the experience of Marseille (France) multidisciplinary team. PMID:21689587

  12. Tumor vascular disruption using various radiation types

    PubMed Central

    2014-01-01

    The feasibility of disrupting a tumor’s vascular structure with various radiation types and radionuclides is investigated. Calculated absorbed dose profiles for photons and 4He ions suggest that low-energy beta-gamma and alpha emitting radionuclides can deposit sufficient absorbed dose to disrupt a tumor’s vascular structure while minimizing the dose outside the blood vessel. Candidate radionuclides uniformly distributed in microspheres are theoretically investigated with respect to their vascular disruption potential and to offer an alternative to 90Y microsphere therapy. Requisite activities of candidate low-energy beta-gamma and alpha emitting radionuclides to facilitate vascular disruption are calculated. PMID:24749005

  13. Gas permeable electrode for electrochemical system

    DOEpatents

    Ludwig, Frank A. (Rancho Palos Verdes, CA); Townsend, Carl W. (Los Angeles, CA)

    1989-01-01

    An electrode apparatus adapted for use in electrochemical systems having an anode compartment and a cathode compartment in which gas and ions are produced and consumed in the compartments during generation of electrical current. The electrode apparatus includes a membrane for separating the anode compartment from the cathode compartment wherein the membrane is permeable to both ions and gas. The cathode and anode for the assembly are provided on opposite sides of the membrane. During use of the membrane-electrode apparatus in electrochemical cells, the gas and ions generated at the cathode or anode migrate through the membrane to provide efficient transfer of gas and ions between the anode and cathode compartments.

  14. Permeability of MDT chambers to water vapor

    E-print Network

    Palestini, S

    2003-01-01

    Tests of MDT chambers performed at the GIF facility and in the H8 test-beam area have shown relative high levels of water vapor contamination in the gas-mixture at the detector output. This effects significantly the drift properties of the MDTs. This note shows that amount of water observed is compatible with approximate estimates based on the permeability of Noryl, used in the tube end-plugs, and of EPDM, used in the O-rings of the on-chamber gas distribution.

  15. Method for decreasing permeability around a wellbore

    SciTech Connect

    Richardson, W.C.; Whittington, L.E.; Morrow, L.R.

    1988-01-26

    A method for decreasing formation permeability in an underground formation around a wellbore is described comprising: injecting an aqueous solution having a pH of about 0.9 to about 3.5 into the formation surrounding a wellbore, the aqueous solution comprising about 2% to about 20% by weight of lignosulfonate, about 2% to about 20% by weight of monomer of acrylic acid, a sufficient amount of an initiator of persulfate to copolymerize the lignosulfonate and the monomer, and about 0% to about 3.0% by weight of a metal slat having a cation of iron, titanium, vanadium, chromium or molybdenum.

  16. Wave propagation in negative index materials

    NASA Astrophysics Data System (ADS)

    Aylo, Rola

    Properties of electromagnetic propagation in materials with negative permittivities and permeabilities were first studied in 1968. In such metamaterials, the electric field vector, the magnetic field vector, and the propagation vector form a left hand triad, thus the name left hand materials. Research in this area was practically non-existent, until about 10 years ago, a composite material consisting of periodic metallic rods and split-ring resonators showed left-handed properties. Because the dimension of the constituents of the metamaterial are small compared to the operating wavelength, it is possible to describe the electromagnetic properties of the composite using the concept of effective permittivity and permeability. In this dissertation, the basic properties of electromagnetic propagation through homogenous left hand materials are first studied. Many of the basic properties of left hand materials are in contrast to those in right hand materials, viz., negative refraction, perfect lensing, and the inverse Doppler effect. Dispersion relations are used to study wave propagation in negative index materials. For the first time to the best of our knowledge, we show that a reduced dispersion relation, obtained from the frequency dependence of the propagation constant by neglecting a linear frequency dependent term, obeys causality. Causality of the propagation constant enables us to use a novel and simple operator formalism approach to derive the underlying partial differential equations for baseband and envelope wave propagation. Various tools for understanding and characterizing left-handed materials are thereafter presented. The transfer matrix method is used to analyze periodic and random structures composed of positive and negative index materials. By random structures we mean randomness in layer position, index of refraction, and thickness. As an application of alternating periodic negative index and positive index structures, we propose a novel sensor using the zero average gap that only appears in such structures which has different properties from the usual Bragg gap occurring in alternating positive index structures. Also in this dissertation, we propose a novel negative index material in the visible range based on nanoparticle dispersed liquid crystal cells. The extended Maxwell Garnett theory, which is combination of the regular Maxwell Garnett and Mie scattering theories, is used to find the effective refractive index of the proposed cell. Nanoparticle dispersed liquid crystal cells can also be used as plasmonic sensors. A theoretical study of such sensors is presented. Finally, fabrication and testing of such cells is proposed and initial progress in fabrication is reported. The final assembly and testing of nanoparticle dispersed liquid crystal cells constitute ongoing and future work.

  17. Markedly Enhanced Permeability and Retention Effects Induced by Photo-Immunotherapy of Tumors

    PubMed Central

    Sano, Kohei; Nakajima, Takahito; Choyke, Peter L.; Kobayashi, Hisataka

    2013-01-01

    A major barrier to cancer treatment is the inability to deliver sufficient concentrations of drug to the tumor without incurring systemic toxicities. Nanomaterials are appealing because they can carry a large drug payload, however, tumor delivery is limited by modest leakage and retention in most tumors. We observed that after photoimmunotherapy (PIT), which is a light mediated treatment based on an antibody-photosensitizer conjugate, there was surprisingly high leakage of nanosized (10–200 nm) agents into the tumor bed. PIT rapidly induced death in perivascular cancer cells leading to immediate and dramatic increases in vascular permeability resulting in up to 24-fold greater accumulation of nanonanomaterials within the PIT-treated tumor compared with controls, an effect termed “super-enhanced permeability and retention” (SUPR). In a treatment study, PIT followed by liposome-containing daunorubicin, DaunoXome (diameter 50 nm), resulted in greater survival in tumor-bearing mice than either PIT or DaunoXome alone. Thus, PIT greatly enhances delivery of nanosized reagents and thus holds promise to improve therapeutic responses. PMID:23214407

  18. Bioinspired tuning of hydrogel permeability-rigidity dependency for 3D cell culture.

    PubMed

    Lee, Min Kyung; Rich, Max H; Baek, Kwanghyun; Lee, Jonghwi; Kong, Hyunjoon

    2015-01-01

    Hydrogels are being extensively used for three-dimensional immobilization and culture of cells in fundamental biological studies, biochemical processes, and clinical treatments. However, it is still a challenge to support viability and regulate phenotypic activities of cells in a structurally stable gel, because the gel becomes less permeable with increasing rigidity. To resolve this challenge, this study demonstrates a unique method to enhance the permeability of a cell-laden hydrogel while avoiding a significant change in rigidity of the gel. Inspired by the grooved skin textures of marine organisms, a hydrogel is assembled to present computationally optimized micro-sized grooves on the surface. Separately, a gel is engineered to preset aligned microchannels similar to a plant's vascular bundles through a uniaxial freeze-drying process. The resulting gel displays significantly increased water diffusivity with reduced changes of gel stiffness, exclusively when the microgrooves and microchannels are aligned together. No significant enhancement of rehydration is achieved when the microgrooves and microchannels are not aligned. Such material design greatly enhances viability and neural differentiation of stem cells and 3D neural network formation within the gel. PMID:25752700

  19. Bioinspired Tuning of Hydrogel Permeability-Rigidity Dependency for 3D Cell Culture

    PubMed Central

    Lee, Min Kyung; Rich, Max H.; Baek, Kwanghyun; Lee, Jonghwi; Kong, Hyunjoon

    2015-01-01

    Hydrogels are being extensively used for three-dimensional immobilization and culture of cells in fundamental biological studies, biochemical processes, and clinical treatments. However, it is still a challenge to support viability and regulate phenotypic activities of cells in a structurally stable gel, because the gel becomes less permeable with increasing rigidity. To resolve this challenge, this study demonstrates a unique method to enhance the permeability of a cell-laden hydrogel while avoiding a significant change in rigidity of the gel. Inspired by the grooved skin textures of marine organisms, a hydrogel is assembled to present computationally optimized micro-sized grooves on the surface. Separately, a gel is engineered to preset aligned microchannels similar to a plant's vascular bundles through a uniaxial freeze-drying process. The resulting gel displays significantly increased water diffusivity with reduced changes of gel stiffness, exclusively when the microgrooves and microchannels are aligned together. No significant enhancement of rehydration is achieved when the microgrooves and microchannels are not aligned. Such material design greatly enhances viability and neural differentiation of stem cells and 3D neural network formation within the gel. PMID:25752700

  20. Permeability of deuterium and helium on poly(vinyl alcohol)

    SciTech Connect

    Carstens, D.H.W.; Ehart, E.P.

    1984-01-01

    The permeabilities of deuterium and helium-4 through poly (vinyl alcohol) (PVA) over the temperature range of 25-125) C are reported. For deuterium, permeabilities ranged from 0.5 X 10/sup -18/ mol-m/m/sup 2/-s-Pa at these two extreme temperatures. Helium permeabilities were roughly five times higher. The effects of different curing temperatures and time on the deuterium permeability were studied found that, to within experimental error, results were the same for samples heat treated at any temperature between 100/sup 0/ C and 140/sup 0/ C. Aluminizing the samples using a special process decreased the permeabilities by a factor of at least 5. A sensitive apparatus constructed around a quadrupole spectrometer was used to measure the very low permeabilities. The apparatus is described in detail. 2 figures, 1 table.

  1. Permeability reduction induced by a nonhydrostatic stress field

    SciTech Connect

    Holt, R.M. (IKU, Trondheim (NO))

    1990-12-01

    Stress-dependent permeability was measured in a high-porosity/high-permeability sandstone with mechanical and fluid-flow parameters similar to those found in typical North Sea reservoirs, particularly the little-investigated effect of triaxial stress configurations. Hydrostatic loading from atmospheric conditions to stress levels comparable to those found in situ causes a slight permeability reduction. When the applied stress is nonhydrostatic, the permeability decrease is more pronounced. In particular, as failure is approached in triaxial loading or unloading, the permeability may be significantly reduced (in some cases to {lt}10% of its initial value). This paper discusses the consequences of these results for interpretation of standard permeability measurements. An example quantifies the formation damage (skin) induced by the near-wellbore stress field.

  2. Diagenesis effect on the pore-permeability relationship

    SciTech Connect

    Yuan, L.; Tillman, A.J.; Ehrlich, R.

    1985-01-01

    The authors are able to precisely estimate air permeability of sedimentary rocks from thin section images of pore size, geometry and connectivity. Assessment of the regression equations linking two-dimensional pore characteristics with permeability permits insight into the pore-geometric factors which affect permeability. This empirical approach is necessary because a large number of theoretical models exist to explain permeability. Their data serve to reflect the feasible models for sedimentary rocks. In many rocks composite models are necessary inasmuch as several discrete pore-complexes may coexist. In other rocks the pore-complex can be modelled as a uniform quasi-crystalline complex. In that case, sheet-like porosity or tubular throats may connect with large moldic pores. The evolution of a pore network under progressive diagenesis of a uniform petrology with permeability from 0.1 to 1600 m.d., illustrates the changing controls on permeability as pore-geometry evolves.

  3. Cerebral Vascular Control and Metabolism in Heat Stress.

    PubMed

    Bain, Anthony R; Nybo, Lars; Ainslie, Philip N

    2015-07-01

    This review provides an in-depth update on the impact of heat stress on cerebrovascular functioning. The regulation of cerebral temperature, blood flow, and metabolism are discussed. We further provide an overview of vascular permeability, the neurocognitive changes, and the key clinical implications and pathologies known to confound cerebral functioning during hyperthermia. A reduction in cerebral blood flow (CBF), derived primarily from a respiratory-induced alkalosis, underscores the cerebrovascular changes to hyperthermia. Arterial pressures may also become compromised because of reduced peripheral resistance secondary to skin vasodilatation. Therefore, when hyperthermia is combined with conditions that increase cardiovascular strain, for example, orthostasis or dehydration, the inability to preserve cerebral perfusion pressure further reduces CBF. A reduced cerebral perfusion pressure is in turn the primary mechanism for impaired tolerance to orthostatic challenges. Any reduction in CBF attenuates the brain's convective heat loss, while the hyperthermic-induced increase in metabolic rate increases the cerebral heat gain. This paradoxical uncoupling of CBF to metabolism increases brain temperature, and potentiates a condition whereby cerebral oxygenation may be compromised. With levels of experimentally viable passive hyperthermia (up to 39.5-40.0°C core temperature), the associated reduction in CBF (?30%) and increase in cerebral metabolic demand (?10%) is likely compensated by increases in cerebral oxygen extraction. However, severe increases in whole-body and brain temperature may increase blood-brain barrier permeability, potentially leading to cerebral vasogenic edema. The cerebrovascular challenges associated with hyperthermia are of paramount importance for populations with compromised thermoregulatory control-for example, spinal cord injury, elderly, and those with preexisting cardiovascular diseases. © 2015 American Physiological Society. Compr Physiol 5:1345-1380, 2015. PMID:26140721

  4. Hereditary intraosseous vascular malformation of the craniofacial region: imaging findings

    Microsoft Academic Search

    I Vargel; P KIRATLI; D AKINCI; Y ERK

    2004-01-01

    Benign vascular lesions can be classified into two categories depending on clinical behaviour and endothelial cell characteristics: neoplasms (haemangiomas) and vascular malformations. However, intraosseous vascular anomaly, previously called intraosseous haemangioma, is a very rare malformation. In our previous study, we described the first hereditary form of intraosseous vascular malformation of the craniofacial region, vascular malformation osseous (VMOS). Characteristic findings are

  5. Tailoring polymersome bilayer permeability improves enhanced permeability and retention effect for bioimaging.

    PubMed

    Lai, Mei-Hsiu; Lee, Sangmin; Smith, Cartney E; Kim, Kwangmeyung; Kong, Hyunjoon

    2014-07-01

    Self-assembled nanoparticles conjugated with various imaging contrast agents have been used for the detection and imaging of pathologic tissues. Inadvertently, these nanoparticles undergo fast, dilution-induced disintegration in circulation and quickly lose their capability to associate with and image the site of interest. To resolve this challenge, we hypothesize that decreasing the bilayer permeability of polymersomes can stabilize their structure, extend their lifetime in circulation, and hence improve the quality of bioimaging when the polymersome is coupled with an imaging probe. This hypothesis is examined by using poly(2-hydroxyethyl-co-octadecyl aspartamide), sequentially modified with methacrylate groups, to build model polymersomes. The bilayer permeability of the polymersome is decreased by increasing the packing density of the bilayer with methacrylate groups and is further decreased by inducing chemical cross-linking reactions between the methacrylate groups. The polymersome with decreased bilayer permeability demonstrates greater particle stability in physiological media and ultimately can better highlight tumors in mice over 2 days compared to those with higher bilayer permeability after labeling with a near-infrared (NIR) fluorescent probe. We envisage that the resulting nanoparticles will not only improve diagnosis but also further image-guided therapies. PMID:24915107

  6. Tailoring Polymersome Bilayer Permeability Improves Enhanced Permeability and Retention Effect for Bioimaging

    PubMed Central

    2015-01-01

    Self-assembled nanoparticles conjugated with various imaging contrast agents have been used for the detection and imaging of pathologic tissues. Inadvertently, these nanoparticles undergo fast, dilution-induced disintegration in circulation and quickly lose their capability to associate with and image the site of interest. To resolve this challenge, we hypothesize that decreasing the bilayer permeability of polymersomes can stabilize their structure, extend their lifetime in circulation, and hence improve the quality of bioimaging when the polymersome is coupled with an imaging probe. This hypothesis is examined by using poly(2-hydroxyethyl-co-octadecyl aspartamide), sequentially modified with methacrylate groups, to build model polymersomes. The bilayer permeability of the polymersome is decreased by increasing the packing density of the bilayer with methacrylate groups and is further decreased by inducing chemical cross-linking reactions between the methacrylate groups. The polymersome with decreased bilayer permeability demonstrates greater particle stability in physiological media and ultimately can better highlight tumors in mice over 2 days compared to those with higher bilayer permeability after labeling with a near-infrared (NIR) fluorescent probe. We envisage that the resulting nanoparticles will not only improve diagnosis but also further image-guided therapies. PMID:24915107

  7. Permeability and contractile responses of collecting lymphatic vessels elicited by atrial and brain natriuretic peptides.

    PubMed

    Scallan, Joshua P; Davis, Michael J; Huxley, Virginia H

    2013-10-15

    Atrial and brain natriuretic peptides (ANP and BNP, respectively) are cardiac hormones released into the bloodstream in response to hypervolaemia or fluid shifts to the central circulation. The actions of both peptides include natriuresis and diuresis, a decrease in systemic blood pressure, and inhibition of the renin-angiotensin-aldosterone system. Further, ANP and BNP elicit increases in blood microvessel permeability sufficient to cause protein and fluid extravasation into the interstitium to reduce the vascular volume. Given the importance of the lymphatic vasculature in maintaining fluid balance, we tested the hypothesis that ANP or BNP (100 nM) would likewise elevate lymphatic permeability (Ps) to serum albumin. Using a microfluorometric technique adapted to in vivo lymphatic vessels, we determined that rat mesenteric collecting lymphatic Ps to rat serum albumin increased by 2.0 ± 0.4-fold (P = 0.01, n = 7) and 2.7 ± 0.8-fold (P = 0.07, n = 7) with ANP and BNP, respectively. In addition to measuring Ps responses, we observed changes in spontaneous contraction amplitude and frequency from the albumin flux tracings in vivo. Notably, ANP abolished spontaneous contraction amplitude (P = 0.005) and frequency (P = 0.006), while BNP augmented both parameters by ?2-fold (P < 0.01 each). These effects of ANP and BNP on contractile function were examined further by using an in vitro assay. In aggregate, these data support the theory that an increase in collecting lymphatic permeability opposes the absorptive function of the lymphatic capillaries, and aids in the retention of protein and fluid in the interstitial space to counteract volume expansion. PMID:23897233

  8. Permeability and contractile responses of collecting lymphatic vessels elicited by atrial and brain natriuretic peptides

    PubMed Central

    Scallan, Joshua P; Davis, Michael J; Huxley, Virginia H

    2013-01-01

    Atrial and brain natriuretic peptides (ANP and BNP, respectively) are cardiac hormones released into the bloodstream in response to hypervolaemia or fluid shifts to the central circulation. The actions of both peptides include natriuresis and diuresis, a decrease in systemic blood pressure, and inhibition of the renin–angiotensin–aldosterone system. Further, ANP and BNP elicit increases in blood microvessel permeability sufficient to cause protein and fluid extravasation into the interstitium to reduce the vascular volume. Given the importance of the lymphatic vasculature in maintaining fluid balance, we tested the hypothesis that ANP or BNP (100 nm) would likewise elevate lymphatic permeability (Ps) to serum albumin. Using a microfluorometric technique adapted to in vivo lymphatic vessels, we determined that rat mesenteric collecting lymphatic Ps to rat serum albumin increased by 2.0 ± 0.4-fold (P= 0.01, n= 7) and 2.7 ± 0.8-fold (P= 0.07, n= 7) with ANP and BNP, respectively. In addition to measuring Ps responses, we observed changes in spontaneous contraction amplitude and frequency from the albumin flux tracings in vivo. Notably, ANP abolished spontaneous contraction amplitude (P= 0.005) and frequency (P= 0.006), while BNP augmented both parameters by ?2-fold (P < 0.01 each). These effects of ANP and BNP on contractile function were examined further by using an in vitro assay. In aggregate, these data support the theory that an increase in collecting lymphatic permeability opposes the absorptive function of the lymphatic capillaries, and aids in the retention of protein and fluid in the interstitial space to counteract volume expansion. PMID:23897233

  9. Age-Related Intimal Stiffening Enhances Endothelial Permeability and Leukocyte Transmigration

    PubMed Central

    Huynh, John; Nishimura, Nozomi; Rana, Kuldeepsinh; Peloquin, John M.; Califano, Joseph P.; Montague, Christine R.; King, Michael R.; Schaffer, Chris B.; Reinhart-King, Cynthia A.

    2013-01-01

    Age is the most significant risk factor for atherosclerosis; however, the link between age and atherosclerosis is poorly understood. During both aging and atherosclerosis progression, the blood vessel wall stiffens owing to alterations in the extracellular matrix. Using in vitro and ex vivo models of vessel-wall stiffness and aging, we show that stiffening of extracellular matrix within the intima promotes endothelial cell permeability—a hallmark of atherogenesis. When cultured on hydrogels fabricated to match the elasticity of young and aging intima, endothelial monolayers exhibit increased permeability and disrupted cell-cell junctions on stiffer matrices. In parallel experiments, we showed a corresponding increase in cell-cell junction width with age in ex vivo aortas from young (10 weeks) and old (21 to 25 months) healthy mice. To investigate the mechanism by which matrix stiffening alters monolayer integrity, we found that cell contractility increases with increased matrix stiffness, mechanically destabilizing cell-cell junctions. This increase in endothelial permeability results in increased leukocyte extravasation, which is a critical step in atherosclerotic plaque formation. Mild inhibition of Rho-dependent cell contractility using Y-27632, an inhibitor of Rho-associated kinase, or siRNA restored monolayer integrity in vitro and in vivo. Our results suggest that extracellular matrix stiffening alone, which occurs during aging, can lead to endothelial monolayer disruption and atherosclerosis pathogenesis. Because previous therapeutics designed to decrease vascular stiffness have been met with limited success, our findings could be the basis for the design of therapeutics that target the Rho-dependent cellular contractile response to matrix stiffening, rather than stiffness itself, to more effectively prevent atherosclerosis progression. PMID:22158860

  10. Permeability of anisotropic tube pumice: Model calculations and measurements

    Microsoft Academic Search

    Heather M. N. Wright; Jeffery J. Roberts; Katharine V. Cashman

    2006-01-01

    We examine permeable flow through porous materials using volcanic pyroclasts with simple pore geometries. Laminar lattice-Boltzmann (LB) fluid flow simulations through 3-D synchrotron x-ray microtomographic images allow us to model fluid flow through anisotropic pumiceous volcanic samples (tube pumice). We find a good correspondence between calculated permeability (using both simple approximations and LB simulations) and maximum laboratory permeability measured parallel

  11. Water Permeability Measurement in Living Cells and Complex Tissues

    Microsoft Academic Search

    A. S. Verkman

    2000-01-01

    .   The identification of molecular water transporters and the generation of transgenic mice lacking water transporting proteins\\u000a has created a need for accurate methods to measure water permeability. This review is focused on methodology to characterize\\u000a water permeability in living cells and complex multicellular tissues. The utility of various parameters defining water transport\\u000a is critically evaluated, including osmotic water permeability

  12. The determination of permeability using a pulse decay technique

    E-print Network

    Rowe, William Charlton

    1985-01-01

    conditions and the elimination of lengthy, complex experiments that would be required if one used a steady state flow method to determine permeability. A Conductivity, Permeability, Damage (CPD) cart manufactured by Terra Tek Systems was used to perform... permeabi1ity sandstones. (After Soeder and Randolph) 11 the CPD cart which was used for conducting the pulse decay experiments, (2) to establish a reliable analysis technique that will provide accurate, reproducible permeability measure- ments...

  13. Computational modeling of vascular anastomoses.

    PubMed

    Migliavacca, Francesco; Dubini, Gabriele

    2005-06-01

    Recent development of computational technology allows a level of knowledge of biomechanical factors in the healthy or pathological cardiovascular system that was unthinkable a few years ago. In particular, computational fluid dynamics (CFD) and computational structural (CS) analyses have been used to evaluate specific quantities, such as fluid and wall stresses and strains, which are very difficult to measure in vivo. Indeed, CFD and CS offer much more variability and resolution than in vitro and in vivo methods, yet computations must be validated by careful comparison with experimental and clinical data. The enormous parallel development of clinical imaging such as magnetic resonance or computed tomography opens a new way toward a detailed patient-specific description of the actual hemodynamics and structural behavior of living tissues. Coupling of CFD/CS and clinical images is becoming a standard evaluation that is expected to become part of the clinical practice in the diagnosis and in the surgical planning in advanced medical centers. This review focuses on computational studies of fluid and structural dynamics of a number of vascular anastomoses: the coronary bypass graft anastomoses, the arterial peripheral anastomoses, the arterio-venous graft anastomoses and the vascular anastomoses performed in the correction of congenital heart diseases. PMID:15772842

  14. Leaf hydraulics II: vascularized tissues.

    PubMed

    Rockwell, Fulton E; Holbrook, N Michele; Stroock, Abraham D

    2014-01-01

    Current models of leaf hydration employ an Ohm's law analogy of the leaf as an ideal capacitor, neglecting the resistance to flow between cells, or treat the leaf as a plane sheet with a source of water at fixed potential filling the mid-plane, neglecting the discrete placement of veins as well as their resistance. We develop a model of leaf hydration that considers the average conductance of the vascular network to a representative areole (region bounded by the vascular network), and represent the volume of tissue within the areole as a poroelastic composite of cells and air spaces. Solutions to the 3D flow problem are found by numerical simulation, and these results are then compared to 1D models with exact solutions for a range of leaf geometries, based on a survey of temperate woody plants. We then show that the hydration times given by these solutions are well approximated by a sum of the ideal capacitor and plane sheet times, representing the time for transport through the vasculature and tissue respectively. We then develop scaling factors relating this approximate solution to the 3D model, and examine the dependence of these scaling factors on leaf geometry. Finally, we apply a similar strategy to reduce the dimensions of the steady state problem, in the context of peristomatal transpiration, and consider the relation of transpirational gradients to equilibrium leaf water potential measurements. PMID:24012489

  15. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High permeability hemodialysis system. (a)...

  16. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High permeability hemodialysis system. (a)...

  17. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High permeability hemodialysis system. (a)...

  18. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High permeability hemodialysis system. (a)...

  19. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High permeability hemodialysis system. (a)...

  20. Permeability of stemming materials for prompt gas sampling

    SciTech Connect

    Beiriger, J.; Trimmer, D.

    1982-01-01

    The permeability and porosity of a suite of man-made granular aggregates and stemming materials currently in use at NTS was measured in 1-D loading as a function of stress. In all cases, the gas permeability was measured at 22 MPa after cycling up and down from 100 to 1200 MPa. Depending on stress and material, permeability decreased up to three orders of magnitude, porosity up to 63% and the sample compacted by as much as 35%. Steel ball bearings were found to retain the highest permeability of all the materials tested. The enhancement of prompt gas sampling through alternate stemming material in the column above the nuclear device is discussed.