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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 212 (1966), S. 1579-1580 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The animals used for this study were the domestic chicken (Oallus gallus), alligator (Alligator mississip-piensis), turtle (Pseudemys scripta), smooth dogfish (Mustelus canis) and spiny dogfish (Squalis acanthias). Blood was collected from the heart of the turtle and alligator, from the wing vein ...
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 220 (1968), S. 509-510 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Blood was obtained by cardiac puncture from turtles (Pseudemys scripta elegans) and 0-1 volume of 0*1 M sodium citrate was added. Thrombocyte preparations were made by centrifuging the blood at 130gr for 2-5 min at 4 C. Ceri-trifugation was carried out for various times because blood viscosity ...
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  • 3
    ISSN: 0886-1544
    Keywords: microvessels ; endothelin ; contraction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A silicone rubber assay is used in conjunction with morphometric measurements to characterize in vitro the contractile properties of retinal pericytes in response to endothelial secreted factors. Factor(s) present in conditioned media derived from pulmonary and retinal microvascular endothelial cells and pulmonary artery endothelial cells promote pericyte contractions. Using a radioimmunoassay significant levels of endothelin immunoreactivity are measured in conditioned media obtained from all three cell lines. Thrombin treatment enhanced endothelin-like secretions by pulmonary microvascular endothelial cells, but significantly reduced levels of endothelin-like immunoreactivity secreted by retinal microvascular endothelial cells. Synthetic endothelin and thromboxane A2 (TxA2) stimulate pericyte contractions, whereas prostaglandin I2 (PGI2) promotes pericyte relaxation. Thrombin and angiotensin II (ang II) have no effect on pericyte contractility. However, using cocultures of pericytes and endothelial cells we observe endothelial-dependent pericyte contractions in response to thrombin and ang II. Thrombin and ang II stimulate the release of endothelial-derived contracting factors, with characteristics similar to endothelin. These data suggest microvascular endothelial cell-pericyte interactions may regulate, at least in part, microvessel contractility.
    Additional Material: 4 Ill.
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  • 4
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Tab.
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  • 5
    ISSN: 0730-2312
    Keywords: actin ; bradykinin ; filamin ; phosphatase ; kinase ; permeability ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Endothelial cell (EC) cytoskeletal proteins are one of the earliest primary targets of second messenger cascades generated in response to inflammatory agonists. Actin binding proteins, by modulating actin gelation-solation state and membrane-cytoskeleton interactions, in part regulate cell motility and cell-cell apposition. This in turn can also modulate interendothelial junctional diameter and permeability. Nonmuscle filamin (ABP-280), a dimeric actincrosslinking protein, promotes orthogonal branching of F-actin and links microfilaments to membrane glycoproteins. In the present study, immunoblot analysis demonstrates that filamin protein levels are low in sparse EC cultures, increase once cell-cell contact is initiated and then decrease slightly at post-confluency. Both bradykinin and ionomycin cause filamin redistribution from the peripheral cell border to the cytosol of confluent EC. Forskolin, an activator of adenylate cyclase, blocks filamin translocation. Bradykinin activation of EC is not accompanied by significant proteolytic cleavage of filamin. Instead, intact filamin is recycled back to the membrane within 5-10 min of bradykinin stimulation. Inhibitors of calcium/calmodulin dependent protein kinase (KT-5926 and KN-62) attenuate bradykinin-induced filamin translocation. H-89, an inhibitor of cAMP-dependent protein kinase, causes translocation of filamin in unstimulated cells. Calyculin A, an inhibitor of protein phosphatases, also causes translocation of filamin in the absence of an inflammatory agent. ML-7, an inhibitor of myosin light chain kinase and phorbol myristate acetate, an activator of protein kinase C, do not cause filamin movement into the cytosol, indicating that these pathways do not modulate the translocation. Pharmacological data suggest that filamin translocation is initiated by the calcium/calmodulin-dependent protein kinase whereas the cAMP-dependent protein kinase pathway prevents translocation. Inflammatory agents therefore may increase vascular junctional permeability by increasing cytoplasmic calcium, which disassembles the microfilament dense peripheral band by releasing filamin from F-actin. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 6
    ISSN: 0730-2312
    Keywords: actin ; permeability ; reoxygenation ; signal transduction ; cytoskeletal rearrangement ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Hypoxia/reoxygenation injury to cultured endothelial cells results in cytoskeletal rearrangement and second messenger activation related to increased monolayer junctional permeability. Cytoskeletal rearrangement by reactive oxygen species may be related to specific activation of the phospholipase D (PLD) pathway. Human umbilical vein endothelial cell monolayers are exposed to H2O2 (100 μM) or metabolites of the PLD pathway for 1-60 min. Changes in cAMP levels, Ca2+ levels, PIP2 production, filamin distribution, and intercellular gap formation are then quantitated. H2O2-induced filamin translocation from the membrane to the cytosol occurs after 1-min H2O2 treatment, while intercellular gap formation significantly increases after 15 min. H2O2 and phosphatidic acid exposure rapidly decrease intracellular cAMP levels, while increasing PIP2 levels in a Ca2+-independent manner. H2O2-induced cAMP decreases are prevented by inhibiting phospholipase D. H2O2-induced cytoskeletal changes are prevented by inhibiting phospholipase D, phosphatidylinositol-4-phosphate kinase, phosphoinositide turnover, or by adding a synthetic peptide that binds PIP2. These data indicate that metabolites produced downstream of H2O2-induced PLD activation may mediate filamin redistribution and F-actin rearrangement. J. Cell. Biochem. 68:511-524, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
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  • 7
    ISSN: 0173-0835
    Keywords: Protein stain ; Electroblotting ; Metal chelate ; Pyrogallol red ; Molybdenum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Certain metal complexes selectively interact with proteins immobilized on solid-phase membrane supports to form brightly colored products. The metal chelates form protein-dye complexes in the presence of metal ions at acidic pH but are eluted from the proteins by immersing membranes in a solution of basic pH that contains other chelating agents. The reversible nature of the protein staining procedure allows for subsequent biochemical analyses, such as immunoblotting, N-terminal and internal protein sequencing. Among the metal complexes evaluated to date, the triazine dye-ferrous complexes (ferene S, ferrozine) and the ferrocyanide-ferric complexes provide the most sensitive detection of proteins immobilized on membranes. While the pyrogallol redmolybdate complex is commonly used in solution-based total protein assays, its utility as a reversible stain for proteins immobilized on membranes has not been reported. Pyrogallol red-molybdate complexes readily stain proteins on nitrocellulose and polyvinyl difluoride membranes with similar sensitivity as ferrozine-ferrous complexes. Analysis of charge-fractionated carrier ampholytes and synthetic polymers of different L-amino acids indicate that binding is prominently via protonated α and ε-amino side chains. Carbamylation of amino groups in bovine serum albumin substantially diminishes pyrogallol red-molybdate binding to the protein. The stain is reversible, resistant to chemical interference, and compatible with immunoblotting.
    Additional Material: 5 Ill.
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  • 8
    ISSN: 0173-0835
    Keywords: Actin ; Pericyte ; Filamin ; Nonmuscle filamin ; ABP-280 ; Esterase ; Endothelium ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two principal forms of the actin binding protein, filamin, are expressed in mammalian cells: nonmuscle and muscle isotypes (FLN-1 and FLN-2). A protein that copurifies with an α-naphthyl acetate hydrolyzing esterase from human omentum microvessel endothelial cells (EC) is isolated by nondenaturing electrophoresis, sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and electroblotting. The purified protein is subjected to in situ trypsin cleavage, reversed-phase high performance liquid chromatography (HPLC) and automated Edman degradation. Six peptide fragments from the protein are identified to have 60 - 66% identity with nonmuscle filamin (ABP-280). Two of these peptides are 100% identical to a previously sequenced human muscle filamin fragment. Polyclonal antibody is produced using a 16-residue synthetic peptide corresponding to a structural β-sheet region of muscle filamin. Compared with a variety of vascular cells evaluated, retinal pericytes express an abundance of both muscle and non-muscle filamin isotypes. Pericytes contain at least 10 times more muscle filamin than human umbilical vein EC and at least three times the amount expressed in human omentum micro-vessel and bovine pulmonary artery EC. Differential detergent fractionation indicates that both filamin isotypes are primarily localized in the cytosol and membrane/organelle fractions of pericytes. Another actin crosslinking protein, α-actinin, is primarily found in the cytosol and cytoskeletal fractions. The dynamic regulation of actin microfilament organization in pericytes may be controlled in part by the two filamin isotypes, which in turn may contribute to pericyte contractility.
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  • 9
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pericytes are contractile cells of the microvascular wall that may influence capillary haemodynamics and permeability. We examined the contractile responses of cultured pericytes to selected vasoactive agents and cAMP agonists. Morphological and biochemical changes associated with these responses were also studied. Pericytes seeded onto silicone rubber contracted when stimulated with histamine or serotonin, relaxed in response to the beta-adrenergic agonist isoproterenol and did not respond to epinephrine. Since hormonal-induced relaxation of vascular smooth muscle involves cAMP, we investigated the ability of cAMP, to modulate pericyte contraction. Dibutyryl cAMP and forskolin (an adenylate cyclase activator) both induced pericyte relaxation and elevated intracellular cAMP levels. Isoproterenol increased cAMP levels but epinephrine had no effect. However, when epiniphrine and isoproterenol were co-incubated with the phosphodiesterase inhibitor 3-isobutyl-l-methylxanthine (IBMX), cAMP was increased to levels above those elicited by these agonists alone. Serotonin and histamine in the presence of IBMX did not affect cAMP levels. These results suggest that certain vasoactive agents may relax pericytes by cAMP-dependent processes. We have shown previously that stress fibres are also involved in pericyte contraction. Hence, changes in the staining patterns of stress fibres in response to these selected agonists were studied. Histamine, serotonin and epinephrine had no apparent effect on stress fibre staining. Dibutyryl cAMP, forskolin, and isoproterenol, which relax pericytes and increase cAMP, disassembled fibres. In summary, the results demonstrate that the contractile activity of cultured pericytesin vitro can be regulated by vasoactive agonists and that changes in cAMP and stress fibres may mediate the regulation.
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  • 10
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Polypeptides of bovine aortic, pulmonary artery, and pulmonary microvascular endothelial cells, as well as vascular smooth muscle cells and retinal pericytes were evaluated by two-dimensional gel electrophoresis. The principal cytoskeletal proteins in all of these cell types were actin, vimentin, tropomyosin, and tubulin. Cultured pulmonary microvascular endothelial cells also expressed 12 unique polypeptides including a 41 kd acidic type 1 and two isoforms of a 52 kd basic type II simple epithelial cytokeratin. Pulmonary microvascular endothelial cell expression of the simple epithelial cytokeratins was maintained in culture in the presence or absence of retinal-derived growth factor, and regardless of whether cells were cultured on gelatin, fibronectin, collagen I, collagen IV, laminin, basement membrane proteins, or plastic. Cytokeratin expression was maintained through at least 50 population doublings in culture. The expression of cytokeratins was found to be regulated by cell density. Pulmonary microvascular endothelial cells seeded at 2.5 × 105 cells/cm2 (confluent seeding) expressed 3.5 times more cytokeratins than cells seeded at 1.25 × 104 cells/cm2 (sparse seeding). Vimentin expression was not altered by cell density. By indirect immunofluorescence microscopy it was determined that the cytokeratins were distributed cytoplasmically at subconfluent cell densities but that cytokeratin 19 sometimes localized at regions of cell-cell contact after cells reached confluence. Vimentin had a cytoplasmic distribution regardless of cell density. These results suggest that pulmonary microvascular endothelial cells have a distinctive cytoskeleton that may provide them with functionally unique properties when compared with endothelial cells derived from the macrovasculature. In conjunction with conventional endothelial cell markers, the presence of simple epithelial cytokeratins may be an important biochemical criterion for identifying pulmonary microvascular endothelial cells.
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