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Query: UMLS:C1832588 (PSS)
 2,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Urocortin is an endogenous vasodilator although the mechanism of vasorelaxation is not completely understood. The hypothesis that an alteration of smooth muscle calcium concentration is involved was tested using isometric tension recording and calcium fluorimetry. The relationship between contraction and intracellular calcium was also estimated. 2. Urocortin produced a concentration dependent relaxation (pD(2) 8.59+/-0.06, n=6) of vessels pre-contracted with a physiological salt solution containing 42 mM KCl (42 mM K-PSS). 3. Removal of the endothelium did not alter the effect of urocortin, pD(2) was 8.49+/-0.11, n=5. 4. Corticotropin-releasing factor relaxed 42 mM K-PSS pre-contracted vessels with less potency compared to urocortin (pD(2) 6.99+/-0.28, n=5). 5. Urocortin at 100 nM relaxed vessels pre-contracted with 42 mM K-PSS by 59.6+/-4.6% (n=8) and vessels pre-contracted with 500 nM noradrenaline by 25.2+/-6.8% (n=6). Both effects were not accompanied by a change in the intracellular calcium concentration. 6. Urocortin at 100 nM produced a significant rightward shift of 0.33+/-0.07 units of normalized intracellular calcium (n=5) of the relationship between tension and intracellular calcium. 7. The urocortin-induced relaxation was considerably reduced in the presence of 0.3 mM Rp-8-CPT-cAMPS, a cyclic AMP-dependent protein kinase (PKA) inhibitor. 8. The PKA-activator Sp-5,6-DCl-cBIMPS relaxed 42 mM K-PSS pre-contracted vessels (pD(2) 4.98+/-0.07, n=6). Sp-5,6-DCl-cBIMPS at 0.1 mM relaxed vessels by 85.3+/-2.5% (n=5), but did not change the intracellular calcium concentration. 9. In conclusion, the data show that urocortin is a potent, endothelium-independent dilator of rat tail arteries and suggest that this effect is mediated by PKA causing a reduction of the sensitivity of the contractile apparatus for calcium.
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PMID:Urocortin relaxes rat tail arteries by a PKA-mediated reduction of the sensitivity of the contractile apparatus for calcium. 1172 64

Redox polyelectrolyte multilayers have been assembled with use of the layer-by-layer (LBL) deposition technique with cationic poly(allylamine) modified with Os(bpy)(2)ClPyCHO (PAH-Os) and anionic poly(styrene)sulfonate (PSS) or poly(vinyl)sulfonate (PVS). Different behavior has been observed in the formal redox potential of the Os(II)/Os(III) couple in the polymer film with cyclic voltammetry depending on the charge of the outermost layer and the electrolyte concentration and pH. The electrochemical quartz crystal microbalance (EQCM) has been used to monitor the exchange of ions and solvent with the external electrolyte during redox switching. At low ionic strength Donnan permselectivity of anions or cations is apparent and the nature of the ion exclusion from the film is determined by the charge of the topmost layer and solution pH. At high electrolyte concentration Donnan breakdown is observed and the osmium redox potential approaches the value for the redox couple in solution. Exchange of anions and water with the external electrolyte under permselective conditions and salt and water under Donnan breakdown have been observed upon oxidation of the film at low pH for the PAH-Os terminating layer. Moreover, at high pH values and with PVS as the terminating layer EQCM mass measurements have shown that cation release was masked by water exchange.
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PMID:Donnan permselectivity in layer-by-layer self-assembled redox polyelectrolye thin films. 1210 31

Swelling and shrinking of polyelectrolyte microcapsules consisting of poly(styrene sulfonate, sodium salt) (PSS) and poly(diallyldimethyl ammonium) chloride (PDADMAC) multilayers have been observed in response to temperature and electrolyte exposure, respectively. Heat-induced capsule swelling and capsule wall volume reduction were observed by confocal laser scanning microscopy (CLSM) and scanning force microscopy (SFM). On the other hand, pronounced shrinking in diameter induced by exposure to an electrolyte was observed in parallel to increases in the thickness of the capsule wall. The estimated wall volume was reduced to two thirds of the control for the salt-exposed capsules and one half for the salt-exposed and simultaneously annealed capsules. This reduction in volume was supposedly mainly caused by the compression of the capsule wall due to the ionic screening from the electrolyte. The highly porous microstructure of the multilayers and loosely bound PSS/PDADMAC complex are thought to be responsible for the structure of the PSS/PDADMAC capsules being easily modulated upon annealing and salt-exposure.
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PMID:Swelling and shrinking of polyelectrolyte microcapsules in response to changes in temperature and ionic strength. 1258 7

A novel technique to introduce free amino groups onto polyester scaffolds via aminolyzing the ester groups with diamine has been developed recently. Positively charged chitosan was then deposited onto the aminolyzed poly(l-lactic acid) (PLLA) membrane surface in a layer-by-layer assembly manner using poly(styrene sulfonate, sodium salt) (PSS) as a negatively charged polyelectrolyte. The layer-by-layer deposition process of PSS and chitosan was monitored by UV-vis absorbance spectroscopy, energy transfer by fluorescence spectroscopy, and advancing contact angle measurements. The existed chitosan obviously improved the cytocompatibility of PLLA to human endothelial cells. The cell attachment, activity, and proliferation on the PLLA membranes assembled with three or five bilayers of PSS/chitosan with chitosan as the outermost layer were better than those with one bilayer of PSS/chitosan or the control PLLA. The cells also showed morphology of an elongated shape with abundant cytoplasm, and a confluent cell layer was reached after being cultured for 4 days. Measurement of von Willebrand factor secreted by these endothelial cells (ECs) verified the endothelial function. Hence, better ECs compatible PLLA were produced.
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PMID:Layer-by-layer assembly to modify poly(l-lactic acid) surface toward improving its cytocompatibility to human endothelial cells. 1262 44

Previously, it was reported that red blood cells (RBCs) are required to demonstrate participation of nitric oxide (NO) in the regulation of rabbit pulmonary vascular resistance (PVR). RBCs do not synthesize NO; hence, we postulated that ATP, present in millimolar amounts in RBCs, was the mediator, which evoked NO synthesis in the vascular endothelium. First, we found that deformation of RBCs, as occurs on passage across the pulmonary circulation with increasing flow rate, evoked increments in ATP release. Here, ATP (300 nM), administered to isolated, salt solution-perfused (PSS) rabbit lungs, decreased total and upstream (arterial) PVR, a response inhibited by NG-nitro-L-arginine methyl ester (L-NAME, 100 microM). In lungs perfused with PSS containing RBCs, L-NAME increased total and upstream PVR. In lungs perfused with PSS containing glibenclamide-treated RBCs, which inhibits ATP release, L-NAME was without effect. Apyrase grade VII (8 U/ml), which degrades ATP to AMP, was without effect on PVR in PSS-perfused lungs. These results are consistent with the hypothesis that ATP, released from RBCs as they traverse the pulmonary circulation, evokes endogenous NO synthesis.
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PMID:Extracellular ATP signaling in the rabbit lung: erythrocytes as determinants of vascular resistance. 1268 60

The effect of the thromboxane A(2) analogue U46619 (9,11-dideoxy-11alpha,9alpha-epoxymethanoprostaglandin F(2)(alpha)) on sustained contraction in the mouse aorta was investigated. U46619 induced concentration-dependent (1 - 100 nM) increases in contraction. These contractile responses were enhanced significantly under high-glucose-physiological salt solution (HG-PSS) (2-fold greater than normal-PSS) conditions. This hyperactivation may be associated with aortic dysfunction in diabetes. However, the mechanisms remain unclear. HG-PSS enhanced U46619-induced accumulation of endogenous diacylglycerol (DG). Phospholipase C inhibitor (U73122) suppressed DG accumulation under normal conditions; however, suppression was not observed under high-glucose conditions. The HG-PSS-induced enhancement of contraction was inhibited by protein kinase C (PKC) inhibitor (calphostin C). This result indicated that accumulated DG might increase PKC activity, which then stimulates DG kinase activation as a feedback mechanism. DG kinase inhibition also suppressed HG-PSS-induced enhancement of contraction. Increased myo-inositol incorporation was detected under high-glucose conditions, indicating an acceleration of phosphatidylinositol (PI)-turnover. Moreover, rho kinase inhibitor (Y27632) suppressed U46619-induced contraction exclusively in normal-PSS. These findings indicated that HG-PSS treatment increases DG synthesis derived from incorporated glucose, PKC and DG kinase activation, and enhances the U46619-induced contraction via acceleration of PI-turnover. This series of responses may be involved in the dysfunction of aorta under high-glucose conditions occurring in association with diabetes.
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PMID:High-glucose enhances a thromboxane A2-induced aortic contraction mediated by an alteration of phosphatidylinositol turnover. 1289 Aug 93

A diffusive gradients in thin films (DGT) technique for measuring Cd and Cu is described using, for the first time, a liquid phase binding layer and a dialysis membrane diffusive layer. The binding phase was a 0.020 M solution of poly(4-styrenesulfonate) (PSS) polyelectrolyte using a specially designed DGT deployment device. The binding properties of Cd2+, Cu2+, and a range of alkali and alkaline earth metal ions to the PSS solution were characterized. The PSS behaved like a cation exchanger with preferential binding to Cd2+ (6.0 micromol mL(-1), log K = 9.0) and Cu2+ (2.5 micromol mL(-1), log K = 8.1) under competitive binding conditions. PSS had a substantial binding capacity at pH > 3 and at competitive Na+ concentrations up to 1.0 M. The DGT devices were successfully validated for Cd2+ (accumulated mass vs time r2 = 0.969, recovery compared with predicted values = 98%) and Cu2+ (r2 = 0.980, recovery = 98%) in synthetic lake water (Windermere). Validation was also undertaken for Cu in a spiked local lake water (Parkwood Pond) (r2 = 0.981, recovery = 46%). The low recovery here was due to complexation of Cu by natural organic matter (14 mg C L(-1)). Field deployments of the DGT devices were successful at measuring Cu concentrations of 0.031-0.63 microg L(-1) in local fresh and salt waterways. These DGT-labile measurements were 0.05-39% of the 0.45-microm-filtered Cu values.
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PMID:Application of a poly(4-styrenesulfonate) liquid binding layer for measurement of Cu2+ and Cd2+ with the diffusive gradients in thin-films technique. 1294 23

A novel capsule composed of an azo dye, Congo red (CR), and different polymers, including poly(styrenesulfonate, sodium salt) (PSS), poly(allylamine hydrochloride) (PAH), and poly(diallyldimethylammonium chloride) (PDDA), have been successfully fabricated by the layer-by-layer self-assembly technique. The stepwise linear deposition process was monitored by means of UV-visible absorption measurements. The formation of hollow capsules was verified by confocal laser scanning microscopy (CLSM) and scanning force microscopy (SFM). The resulting hollow PSS/PAH/CR/PDDA capsules displayed a sensitive response to visible light. Optical changes of the hollow capsules prior to and after the photoreaction were investigated in detail by means of UV-visible spectroscopy, CLSM, and SFM. It was found that the photochemical reaction of the assembled hollow capsules depends strongly on the matrix. Qualitative results on the permeability of the hollow capsule walls with CR as one component indicate that the permeability of the walls can be easily photo-controlled at varying irradiation time intervals without addition of external chemicals.
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PMID:Self-assembly, optical behavior, and permeability of a novel capsule based on an azo dye and polyelectrolytes. 1525 85

We synthesized an ionic amphiphilic diblock copolymer, poly(hydrogenated isoprene)-b-poly(styrenesulfonic acid) (PIp-h2-b-PSS), by living anionic polymerization, and the nanostructure of its monolayer spread on a water surface was directly investigated by the in situ X-ray reflectivity technique. The monolayer of the diblock copolymer on a water surface had a smooth hydrophobic PIp-h2 layer on water and a "carpet"/polymer brush double layer in a hydrophilic sodium polystyrene sulfonate (PSSNa) layer under the water. The surface pressure dependence and PSSNa chain length dependence of the PIp-h2 layer thickness and the brush nanostructure were quantitatively studied. The effect of salt concentration in the subphase was also investigated in aqueous solutions containing 0-2 M NaCl. The salt effect on monolayer structure occurred at around 0.2 M. The thickness of the PSS brush layer decreased at salt concentrations above 0.2 M, while no structural change was observed below 0.2 M. This critical salt concentration is thought to be related to the balance of ionic concentrations inside the brush and in bulk solution.
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PMID:Synthesis and nanostructure of strong polyelectrolyte brushes in amphiphilic diblock copolymer monolayers on a water surface. 1527 82

The amount of counterions in layer-by-layer (LBL) films of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) has been determined with X-ray photoelectron spectroscopy (XPS) for films prepared from solutions with various NaCl concentrations. Sodium and chloride counterions are present in LBL films produced from salt solutions, which are located at the surface and in the bulk of the films. The percentage of bulk counterions increases with the ionic strength of the polyelectrolyte before reaching a constant value. The bulk sodium/sulfur percentage ratios tend to 0.8 for samples washed with pure water and for samples washed with NaCl aqueous solutions, while the bulk chlorine/nitrogen percentage ratios tend to 0.5 for the same samples. The ratio between the percentages of polyelectrolyte ionic groups lies close to unity for all samples, indicating that counterions do not contribute to charge compensation in the polyelectrolyte during the adsorption process. The presence of counterions in LBL films is explained by Manning condensation near the polyelectrolyte ionic groups, leading to inter-polyelectrolyte ionic bondings via ionic networks. It is believed that condensation leads to the formation of NaCl crystallites in these LBL films, which was confirmed by X-ray diffraction measurements.
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PMID:Counterions in poly(allylamine hydrochloride) and poly(styrene sulfonate) layer-by-layer films. 1535 79


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