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Maleate
Kinds of Maleate Selected AbstractsSuccessful Repair of Aortic and Mitral Incompetence Induced by Methylsergide Maleate: Confirmation by Intraoperative Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 3 2003D.O., Thomas Joseph Methylsergide maleate, an effective anti-migraine medication, has a well-documented association with left-sided cardiac valve dysfunction. Prior reports have described cardiac valve dysfunction in patients using methylsergide chronically for a minimum of 6 years, with surgical intervention consisting of valve replacement for patients with intractable congestive heart failure. We report a 51-year-old woman who developed severe mitral and aortic valvular dysfunction after taking methylsergide maleate for migraine headaches for a period of 19 months, and who subsequently underwent aortic and mitral valve repair with excellent short-term results. (ECHOCARDIOGRAPHY, Volume 20, April 2003) [source] Self-assembly of Two Novel Supramolecular Frameworks Based on Flexible Oligo- , -Pyridylamino Ligands and Copper(II) MaleateCHINESE JOURNAL OF CHEMISTRY, Issue 10 2005Cai-Hua Zhou Abstract Two novel supramolecular complexes, [Cu(bpapa)(mal)]·H2O·CH3OH (1) and {[Cu(bpapap)](Hmal)2}·2H2O (2) [bpapa=bis-[6-(2-pyridylamino)pyrid-2-yl]amine, bpapap=2,6-bis-[6-(pyrid-2-ylamino)pyrid-2-ylamino]-pyridine, mal=maleate dianion] were rationally designed and synthesized based on flexible multidentate ligands and copper(II) maleate. Complexes 1 and 2 were all characterized by elemental analysis, spectroscopic techniques, thermal analysis and single crystal X-ray diffraction analysis. Complex 1 is of an infinite 3-D supramolecular framework constructed by 2-D sheets to contain 1-D helical chains formed by intermolecular hydrogen bond interactions between the non-coordinated oxygen atoms from maleate and nitrogen atoms from amino groups of bpapa. Complex 2 also takes a 3-D supramolecular structure, which is built from 2-D rhombic sheets produced by sequential dimer units. Interestingly, three pairs of symmetrical hydrogen bonds generate these dimer units. [source] Great Framework Variation of Polymers in the Manganese(II) Maleate/,,,,-Diimine System: Syntheses, Structures, and Magneto-Structural CorrelationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2003Chengbing Ma Abstract Three novel manganese(II) coordination polymers, [Mn (maleate)(phen)]n (1; phen = 1,10-phenanthroline), [Mn(maleate)(phen)]n·nH2O (2), and [Mn(maleate)(bpy)]n (3; bpy = 2,2,-bipyridine), have been synthesized by treatment of Mn2+ with maleic acid with participation of chelate diimine ligands, and have been identified by single-crystal X-ray diffraction to have either one-dimensional (1D) zigzag chain structures (1 and 2) or a two-dimensional (2D) sinuous layer structure (3). Each maleate dianion coordinates to three Mn centers, in different bridging modes (syn - anti in 1 and 2, syn - syn and anti - anti in 3). These compounds represent an interesting example of structural topology variation from 1D to 2D mediated by chemically similar auxiliary chelate ligands. Variable-temperature magnetic susceptibility measurements show weak anti-ferromagnetic exchange interactions between the adjacent MnII ions, with J = ,0.06 cm,1 (2) and J = ,1.3 cm,1, zJ, = ,0.27 cm,1 (3). The differences in the magnitudes of these coupling interactions agree well with the nature of the carboxylate-bridging coordination of maleate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] The Synthesis of 2-Ketopiperazine Acetic Esters and Amides from Ethylenediamines with Maleates and Maleimides.CHEMINFORM, Issue 21 2003Matthew M. Abelman Abstract For Abstract see ChemInform Abstract in Full Text. [source] Allergic contact dermatitis from dibucaine hydrochloride, chlorpheniramine maleate, and naphazoline hydrochloride in an over-the-counter topical antisepticCONTACT DERMATITIS, Issue 1 2009Yoshika Yamadori No abstract is available for this article. [source] Successful Repair of Aortic and Mitral Incompetence Induced by Methylsergide Maleate: Confirmation by Intraoperative Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 3 2003D.O., Thomas Joseph Methylsergide maleate, an effective anti-migraine medication, has a well-documented association with left-sided cardiac valve dysfunction. Prior reports have described cardiac valve dysfunction in patients using methylsergide chronically for a minimum of 6 years, with surgical intervention consisting of valve replacement for patients with intractable congestive heart failure. We report a 51-year-old woman who developed severe mitral and aortic valvular dysfunction after taking methylsergide maleate for migraine headaches for a period of 19 months, and who subsequently underwent aortic and mitral valve repair with excellent short-term results. (ECHOCARDIOGRAPHY, Volume 20, April 2003) [source] Influence of methanol on the enantioresolution of antihistamines with carboxymethyl-,-cyclodextrin in capillary electrophoresisELECTROPHORESIS, Issue 16 2004Ann Van Eeckhaut Abstract According to the model of Wren and Rowe, the separation between two enantiomers in capillary electrophoresis (CE) decreases if an organic modifier is added to the run buffer containing a neutral cyclodextrin (CD) in a concentration below its optimal value in a solvent-free system. In previous work, however, it was observed that the addition of methanol to the background electrolyte (BGE) containing not charged carboxymethyl-,-CD in a concentration below its optimal value, increased the enantioresolution of dimetindene maleate. The enantioresolution decreased when other organic modifiers (ethanol, isopropanol or acetonitrile) were added and/or when other neutral (,-CD, hydroxypropyl-,-CD) or chargeable (carboxyethyl-,- and succinyl-,-CD) CDs were used. In this CE study further attempts are made to elucidate the observed phenomena through investigating other basic drugs. The effect of organic modifier and CD concentration on the enantioseparation was studied by means of central composite designs. It is shown that obtaining this increase in enantioresolution depends upon the type of CD, the type of organic modifier, and the structure of the analytes. It was also observed that small differences in the structure of the analytes or the CD could have an influence on the enantioresolution. The addition of methanol also resulted in different effects on the resolution of closely related analytes. [source] Unusual T4(1) Water Chain Stabilized in the One-Dimensional Chains of a Copper(II) Coordination PolymerEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007Yi Jin Abstract A novel T4(1) water chain in a new CuII coordination polymer, {[Cu(C4H6N2)2(C4H2O4)] (H2O)3}n (1, where C4H6N2 = 2-methylimidazole, C4H2O4 = maleate), has been synthesized and structurally characterized by single-crystal X-ray diffraction. Thermogravimetry, infrared spectroscopy, elemental analysis, and magnetic analysis have also been used to characterize 1. Complex 1 crystallizes in the trigonal space group P3221, and the 1-D chains composed of cyclic water tetramers play an important role in stabilizing the overall polymeric structure. Furthermore, this 1-D water chain presents an unusual association mode of water molecules.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Hexaazamacrocycle Containing Pyridine and Its Dicopper Complex as Receptors for Dicarboxylate AnionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2005Feng Li Abstract The host,guest binding interactions of the hexaazamacrocycle [26]py2N4, in its tetraprotonated form H4[26]py2N44+ as well as in its dicopper(II) complex [Cu2([26]py2N4)(H2O)4]4+, with dicarboxylate anions of different stereoelectronicrequirements, such as oxalate (ox2,), malonate (mal2,), succinate (suc2,), fumarate (fu2,) and maleate (ma2,), were evaluated. The association constants were determined using potentiometric methods in aqueous solution, at 298.0 K and 0.10 mol·dm,3 KCl. These values for the tetraprotonated ditopic receptor with the dicarboxylate anions revealed that the main species in solution corresponds to the formation of {H4[26]py2N4(A)}2+ (pH , 4,9), A being the substrate anion. The values determined are not especially high, but the receptor exhibits selectivity for the malonate anion. The study of the cascade complexes revealed several species in solution, involving mononuclear and dinuclear complexes, mainly protonated and hydrolysed species, as well as the expected complexes [Cu2([26]py2N4)(A)(H2O)x]2+ or [Cu2([26]py2N4)(A)2(H2O)y]. Ox2, and mal2, form cascade complexes with only one anion, which will necessarily bridge the two copper atoms because of the symmetrical arrangement of the dinuclear complex. The two other studied anions, suc2, and ma2,, form species involving two substrate anions, although species with only one suc2, anion were also found. UV/Vis and EPR spectroscopy have shown that the dicopper complex can operate as a sensor to detect and quantitatively determine oxalate spectrophotometrically because of the red shift of the maximum of the visible band observed by addition of ox2, to an aqueous solution of the dinuclear copper complex. However the selectivity of [Cu2([26]py2N4)(H2O)4]4+ as a receptor for ox2, in the studied series is not sufficiently high to detect ox2, spectrophotometrically in the presence of the other anions. Molecular dynamics simulations indicated that the H4[26]py2N44+ receptor provides a large and flexible cavity to accommodate the studied anions. Molecular recognition is based in electrostatic interactions rather than in multiple hydrogen-bonding interactions acting cooperatively. By contrast, the [Cu2([26]py2N4)]4+ receptor has a well-shaped cavity with adequate size to uptake these anions as bridging ligands with formation of four Cu,O bonds. The ox2, anion is encapsulated within the cascade complex while the remaining anions are located above the N6 macrocyclic plane, suggesting a selective coordination behaviour of this receptor. In spite of our molecular simulation being carried out in gas phase, the modelling results are consistent with the solution studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Great Framework Variation of Polymers in the Manganese(II) Maleate/,,,,-Diimine System: Syntheses, Structures, and Magneto-Structural CorrelationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2003Chengbing Ma Abstract Three novel manganese(II) coordination polymers, [Mn (maleate)(phen)]n (1; phen = 1,10-phenanthroline), [Mn(maleate)(phen)]n·nH2O (2), and [Mn(maleate)(bpy)]n (3; bpy = 2,2,-bipyridine), have been synthesized by treatment of Mn2+ with maleic acid with participation of chelate diimine ligands, and have been identified by single-crystal X-ray diffraction to have either one-dimensional (1D) zigzag chain structures (1 and 2) or a two-dimensional (2D) sinuous layer structure (3). Each maleate dianion coordinates to three Mn centers, in different bridging modes (syn - anti in 1 and 2, syn - syn and anti - anti in 3). These compounds represent an interesting example of structural topology variation from 1D to 2D mediated by chemically similar auxiliary chelate ligands. Variable-temperature magnetic susceptibility measurements show weak anti-ferromagnetic exchange interactions between the adjacent MnII ions, with J = ,0.06 cm,1 (2) and J = ,1.3 cm,1, zJ, = ,0.27 cm,1 (3). The differences in the magnitudes of these coupling interactions agree well with the nature of the carboxylate-bridging coordination of maleate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] N -methyl- d -aspartate receptor-mediated increase of neurogenesis in adult rat dentate gyrus following strokeEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2001Andreas Arvidsson Abstract Neurogenesis in the adult rat dentate gyrus was studied following focal ischemic insults produced by middle cerebral artery occlusion (MCAO). Animals were subjected to either 30 min of MCAO, which causes damage confined to the striatum, or 2 h of MCAO, which leads to both striatal and cortical infarction. When compared to sham-operated rats, MCAO-rats showed a marked increase of the number of cells double-labelled for 5-bromo-2,-deoxyuridine-5,-monophosphate (BrdU; injected during 4,6 days postischemia) and neuronal-specific antigen (NeuN; a marker of postmitotic neurons) in the ipsilateral dentate granule cell layer and subgranular zone at 5 weeks following the 2 h insult. Only a modest and variable increase of BrdU-labelled cells was found after 30 min of MCAO. The enhanced neurogenesis was not dependent on cell death in the hippocampus, and its magnitude was not correlated to the degree of cortical damage. Systemic administration of the N -methyl- d -aspartate (NMDA) receptor blocker dizocilpine maleate (MK-801) completely suppressed the elevated neurogenesis following 2 h of MCAO. Our findings indicate that stroke leads to increased neurogenesis in the adult rat dentate gyrus through glutamatergic mechanisms acting on NMDA receptors. This modulatory effect may be mediated through changes in the levels of several growth factors, which occur after stroke, and could influence various regulatory steps of neurogenesis. [source] Preparation of N -Glycosylhydroxylamines and Their Oxidation to Nitrones for the Enantioselective Synthesis of IsoxazolidinesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2003Stefano Cicchi Abstract N -benzyl- and N -methyl- N -glycosylhydroxylamines 3a,i were conveniently obtained by reaction of sugars with N -substituted hydroxylamines according to a novel procedure. Subsequent oxidation occurred at the alkyl group, selectively affording the corresponding C -phenyl- and C -unsubstituted N -glycosylnitrones. C -phenyl- N -glycosylnitrones 10 and 13 underwent highly stereoselective 1,3-dipolar cycloaddition with dimethyl maleate, with the sugar moiety acting as a chiral auxiliary. Final removal of the glycosyl moiety afforded enantiopure enantiomeric isoxazolidines 17 and ent -17 which are oxa-analogues of proline diester derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Neurochemical regulation of swallowing reflex in guinea pigsGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 1-2 2001Yu X Jia Background: Most peripheral afferent fibers involved in swallowing travel through the glossopharyngeal and vagus nerves and terminate in the nucleus of the tractus solitarius (NTS) and nodose ganglion (NG). Sensory neurons within the NTS and NG contain several neurotransmitters, including acetylcholine, histamine, serotonin and dopamine. The roles of these four neurotransmitters were investigated. Methods: The effects of atropine (muscarinic cholinergic receptor antagonist); pyrilamine maleate (PM, histamine H1 receptor antagonist); cimetidine (histamine H2 receptor antagonist); 8-hydroxy-2-(di- n -propylamino)-tetralin (8-OH-DPAT, specific 5-HT1A receptor agonist); and selective dopamine D1 receptor antagonist (Sch-23390) on the number of swallows elicited by distilled water in anesthetized guinea pigs were investigated. Results: Atropine (0.2 mg/kg) inhibited swallowing by approximately 70%; PM (30 mg/kg) inhibited swallowing by approximately 60%; cimetidine (30 mg/kg) inhibited swallowing by approximately 52.9% and Sch-23390 (chronic treatment) inhibited swallowing by approximately 40%. In contrast, 8-OH-DPAT did not alter the number of swallows. Chronic pretreatment of Sch-23390 markedly decreased the substance P (SP) content in the pharyngeal mucosa and the esophagus. Conclusion: These findings indicate that acetylcholine, histamine and dopamine are involved in the regulation of the swallowing reflex, whereas it is unlikely that serotonin is involved. [source] Expression and regulation of L-cystine transporter, system xc,, in the newly developed rat retinal Müller cell line (TR-MUL)GLIA, Issue 3 2003Masatoshi Tomi Abstract The purpose of the present study was to elucidate the expression and regulation of the L-cystine transporter, system xc,, in Müller cells. In this study, newly developed conditionally immortalized rat Müller cell lines (TR-MUL) from transgenic rats harboring the temperature-sensitive SV 40 large T-antigen gene were used as an in vitro model. TR-MUL cells express large T-antigen and grow well at 33°C with a doubling time of 30 h, but do not grow at 39°C. TR-MUL cells express typical Müller cell markers such as S-100, glutamine synthetase, and EAAT1/GLAST, whereas EAAT2/GLT-1 and EAAT5 are not detected. TR-MUL cells also exhibit little or no expression of glial fibrillary acidic protein. We found that TR-MUL5 cells exhibited [14C]L-cystine uptake activity and expressed xCT and 4F2hc, which involve system xc,. The uptake of [14C]L-cystine was significantly inhibited by L-glutamic acid and L-aspartic acid, whereas L-leucine had no effect. Following diethyl maleate (DEM) treatment, the glutathione concentration in TR-MUL5 cells was reduced in the first 24 h, then gradually recovered for more than 24 h. The L-cystine uptake rate and the xCT expression level in TR-MUL5 cells were enhanced by DEM treatment. In contrast, the 4F2hc expression level was unchanged. In conclusion, TR-MUL cells have the properties of Müller cells and exhibit system xc, -mediated L-cystine uptake activity. The oxidative stress conditions following DEM treatment activate L-cystine transport in TR-MUL cells due to the enhanced transcription of the xCT gene. GLIA 9999:000,000, 2003. © 2003 Wiley-Liss, Inc. [source] Controlled Release of Perfumery Alcohols by Neighboring-Group Participation.HELVETICA CHIMICA ACTA, Issue 8 20032-(Hydroxymethyl)-, 2-Carbamoylbenzoates, Comparison of the Rate Constants for the Alkaline Hydrolysis of 2-Acyl- A series of 2-acylbenzoates 1 and 2, 2-(hydroxymethyl)benzoates 3, 2-carbamoylbenzoates 4,6, as well as the carbamoyl esters 7 or 8 of maleate or succinate, respectively (see Fig.,2), were prepared in a few reaction steps, and the potential use of these compounds as chemical delivery systems for the controlled release of primary, secondary, and tertiary fragrance alcohols was investigated. The rate constants for the neighboring-group-assisted alkaline ester hydrolysis were determined by anal. HPLC in buffered H2O/MeCN solution at different pH (Table,1). The rates of hydrolysis were found to depend on the structure of the alcohol, together with the precursor skeleton and the structure of the neighboring nucleophile that attacks the ester function. Primary alcohols were released more rapidly than secondary and tertiary alcohols, and benzoates of allylic primary alcohols (e.g., geraniol) were hydrolyzed 2,4 times faster than their homologous saturated alcohols (e.g., citronellol). For the same leaving alcohol, 2-[(ethylamino)carbonyl]benzoates cyclized faster than the corresponding 2-(hydroxymethyl)benzoates, and much faster than their 2-formyl and 2-acetyl analogues (see, e.g., Fig.,4). Within the carbamoyl ester series, 2-[(ethylamino)carbonyl]benzoates were found to have the highest rate constants for the alkaline ester hydrolysis, followed by unsubstituted 2-(aminocarbonyl)benzoates, or the corresponding isopropyl derivatives. To rationalize the influence of the different structural changes on the hydrolysis kinetics, the experimental data obtained for the 2-[(alkylamino)carbonyl]benzoates were compared with the results of density-functional computer simulations (Table,2 and Scheme,4). Based on a preliminary semi-empirical conformation analysis, density-functional calculations at the B3LYP/6-31G** level were carried out for the starting precursor molecules, several reaction intermediates, and the cyclized phthalimides. For the same precursor skeleton, these simple calculations were found to model the experimental data correctly. With an understanding of the influence of structural parameters on the rate constants obtained in this work, it is now possible to influence the rates of hydrolysis over several orders of magnitude, to design tailor-made precursors for a large variety of fragrance alcohols, and to predict their efficiency as controlled-release systems in practical applications. [source] A convenient synthesis of substituted 3-alkoxycarbonyl-,,,-unsaturated esters with predominant Z-selectivityHETEROATOM CHEMISTRY, Issue 3 2003Yanchang Shen The consecutive reaction of bis[2,2,2-trifluoroethyl]phosphite with sodium hydride, dimethyl maleate, and aldehydes gives 3-alkoxycarbonyl-,,,-unsaturated esters with predominant Z-selectivity in 62,94% yields (Z/E = 85,60:15,40). The Z- and E-isomer can be separated conveniently by column chromatography. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:276,279, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10142 [source] Mechanisms of resistance to spinosad in the western flower thrip, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)INSECT SCIENCE, Issue 2 2008Shu-Yun Zhang Abstract Cross-resistance, resistance mechanisms, and mode of inheritance of spinosad resistance were studied in the western flower thrip, Frankliniella occidentalis (Pergande). Spinosad (naturalyte insecticide) showed low cross-resistance to prothiophos (organophosphorus insecticide) and chlorphenapyr (respiratory inhibitor) showed some cross-resistance to thiocyclam (nereistoxin). The synergists PBO (piperonyl butoxide), DEM (diethyl maleate), and DEF (s, s, s-tributyl phosphorotrithioate) did not show any synergism on the toxicity of spinosad in the resistant strain (ICS), indicating that metabolic-mediated detoxification was not responsible for the spinosad resistance, suggesting that spinosad may reduce sensitivity of the target site: the nicotinic acetylcholine receptor and GABA receptor. Following reciprocal crosses, dose-response lines and dominance ratios indicated that spinosad resistance was incompletely dominant and there were no maternal effects. The results of backcross showed that spinosad resistance did not fit a single-gene hypothesis, suggesting that resistance was influenced by several genes. [source] Kinetics and thermodynamic parameters of the thermal decomposition of imipramine hydrochloride and trimipramine maleateINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2003Rafie H. Abu-Eittah Thermal decomposition of imipramine hydrochloride and trimipramine maleate has been investigated isothermally and nonisothermally. The kinetic parameters, namely the activation energy Ea and the Arrhenius preexponential term A, were calculated. Applying the theory of activated complex to the process of decomposition one calculated ,S,, ,H,, and ,G, for the reaction. The values of Ea as well as the thermodynamic functions did not vary significantly with temperature of the reaction whereas the preexponential term showed a significant dependence on the reaction temperature. Both imipramine hydrochloride and trimipramine maleate showed two main steps of decomposition. Each step proved to be a first-order reaction. The rate constant was calculated for each step, and the results were analyzed statistically. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 166,179, 2003 [source] Studies on some enzymes involved in insecticide resistance in fenitrothion-resistant and -susceptible strains of Musca domestica L. (Dipt, Muscidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 9 2002S. Ahmed Co-administration of fenitrothion with three synergists, namely piperonyl butoxide (PBO), tributylphosphorotrithioate (DEF) and diethyl maleate (DEM) was investigated, respectively, at 1 : 5, 1 : 5 and 1 : 10 ratio. This co-administration of fenitrothion with PBO, DEF and DEM caused a decrease in the doses which produced 50% lethality (LD50s) in 571ab but had no synergistic effect on fenitrothion toxicity was observed in the Cooper strain. The effect of topical application of fenitrothion alone and in combination with PBO, DEF and DEM at the LD50 level on some enzyme activities in 571ab and Cooper strains was examined. The application of fenitrothion alone and in combination with DEF and DEM at LD50 level caused a significant decrease in activities of total esterases, acetylcholinesterase (AChE) and glutathione S-transferase (GST) in the 571ab strain. The decrease in GST activity was not significant in treated flies of the Cooper strain when compared with GST activity of control flies. A non-significant effect on total cytochrome P450 level was observed with fenitrothion alone and the fenitrothion + PBO treatment. No increase in activity level of total esterases, AChE and GST was found, which might suggest that changes in activity level of these enzymes are not related to fenitrothion resistance in the 571ab strain. [source] Fabrication and properties of crosslinked poly(propylene carbonate maleate) gel polymer electrolyte for lithium-ion batteryJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Xiaoyuan Yu Abstract The poly(propylene carbonate maleate) (PPCMA) was synthesized by the terpolymerization of carbon dioxide, propylene oxide, and maleic anhydride. The PPCMA polymer can be readily crosslinked using dicumyl peroxide (DCP) as crosslinking agent and then actived by absorbing liquid electrolyte to fabricate a novel PPCMA gel polymer electrolyte for lithium-ion battery. The thermal performance, electrolyte uptake, swelling ratio, ionic conductivity, and lithium ion transference number of the crosslinked PPCMA were then investigated. The results show that the Tg and the thermal stability increase, but the absorbing and swelling rates decrease with increasing DCP amount. The ionic conductivity of the PPCMA gel polymer electrolyte firstly increases and then decreases with increasing DCP ratio. The ionic conductivity of the PPCMA gel polymer electrolyte with 1.2 wt % of DCP reaches the maximum value of 8.43 × 10,3 S cm,1 at room temperature and 1.42 × 10,2 S cm,1 at 50°C. The lithium ion transference number of PPCMA gel polymer electrolyte is 0.42. The charge/discharge tests of the Li/PPCMA GPE/LiNi1/3Co1/3Mn1/3O2 cell were evaluated at a current rate of 0.1C and in voltage range of 2.8,4.2 V at room temperature. The results show that the initial discharge capacity of Li/PPCMA GPE/LiNi1/3Co1/3Mn1/3 O2 cell is 115.3 mAh g,1. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Preparation and characteristic of electric stimuli responsive hydrogel composed of polyvinyl alcohol/poly (sodium maleate- co -sodium acrylate)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Yi Gao Abstract Maleic anhydride was used to preparare polyvinyl alcohol/poly (sodium maleate- co -sodium acrylate) hydrogels (PVA/poly(SMA-SAA)) by a repeated frost-defrost process because of its higher charge density and potential electric stimuli sensitivity. The bending angle was measured in a noncontact electric field using carbon as plate electrodes. It was found that the bending angle was dependent on various factors, including composition of hydrogel, concentration of NaCl solution, types of electrolyte solution, and electric voltage. It exhibited that the bending angle increased when the concentration of NaCl solutions and the electric voltages increased. An abnormal bending direction was observed, and it was affected not only by the kinds of hydrogels, but also by the exterior variations. The hydrogel showed good reversibility in on-off electric field and could be a candidate for practical application. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Changes in the levels of glutathione after cellular and cutaneous damage induced by squalene monohydroperoxideJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2001Katsuyoshi Chiba Abstract Squalene monohydroperoxide (Sq-OOH), the initial product of ultraviolet-peroxidated squalene, was used to investigate the effect of peroxidative challenge upon the glutathione contents in rabbit ear skin and primary-cultured fibroblasts derived from rabbit ear skin. The cellular reduced glutathione (GSH) contents decreased during 30-minute incubations in vitro with Sq-OOH, and oxidized glutathione (GSSG) was formed concomitantly, indicating that Sq-OOH had a potential for GSH-depleting activity in vitro. When Sq-OOH was applied topically to the skin in vivo, only GSSG contents increased significantly within 30 minutes. Moreover, pretreatment with the GSH depletors, DL -buthionine sulfoximine (BSO) and diethyl maleate (DEM), could potentiate the cytotoxicity and comedogenicity induced by Sq-OOH. These findings suggest that the endogenous antioxidant, glutathione, is quite sensitive to Sq-OOH and may be an important material for protecting cells and/or tissues against the oxidative stress induced by Sq-OOH treatment. © 2001 John Wiley & Sons, Inc. J Biochem Mol Toxicol 15:150,158, 2001 [source] Renal cortex remodeling in nitric oxide deficient rats treated with enalaprilJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 1 2004Noemi Barbuto Abstract The kidney NO synthase is one of the most important renal controlling systems. This paper aims the quantification of renal cortical components involved in blood pressure regulation under NOs blockade. Spontaneous hypertensive rats (SHRs) are submitted to chronic blockade of NOs by L-nitro-arginine-methyl-ester (L-NAME) and an ACE inhibitor (enalapril) in comparison with the normotensive Wistar rats. Twenty SHRs and 5 Wistar rats were divided in 5 groups and observed for 21 days for blood pressure (BP) and serum creatinine: control Wistar (5) (C-W), control SHR (5) (C-SHR), L-SHR (5) - received L-NAME 30 mg/kg/day, L+E-SHR (5) - received L-NAME and Enalapril maleate 15 mg/kg/day, E-SHR (5) - received Enalapril maleate. A quantitative morphometric study (glomerular density, QA[g1], interstitium volume density, Vv[i], tubular surface and length densities, Sv[t] and Lv[t]) were performed at the end. The BP reached 226±15 mmHg in L-SHR group. The BP difference between the L-SHR and the C-SHR groups was significant from the first week while the E-SHR group became significant from the second week. At the end of the experiment the BP of the E-SHR group was similar to the BP in the C-W group. The QA[g1] was similar among C-SHR, L-SHR and L+E-SHR groups and no difference was found between E-SHR and C-W groups. In the L-SHRs serum creatinine was greatly increased, and microscopy showed thickening of arteriolar tunica media with an increase of the wall-to-lumen ratio, perivascular fibrosis, inflammatory infiltrated, tubular atrophy and interstitial fibrosis with focal segmental glomerulosclerosis. The use of enalapril was not completely efficient in reducing BP and morphological injury when the hypertension of SHRs was increased with the NOs blockade suggesting that NO deficiency-induced hypertension is not entirely mediated by the RAAS. [source] Rosiglitazone maleate (BRL 49653-C); the preparation of [14C] and [3H] isotopomersJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2001Tabassum Kirefu Abstract The glitazone insulin sensitisers are an important class of pharmaceuticals for the treatment of Type 2 diabetes. Syntheses of [methyl - 14C] and [3H]rosiglitazone maleate (BRL 49653-C), marketed by SmithKline Beecham Pharmaceuticals as Avandia® are described. [Methyl - 14C]BRL 49653-C was prepared in 5 steps in 12.6% overall radiochemical yield from K[14C]CN. Catalytic reduction with tritium gas of a dibromo derivative gave [3H]rosiglitazone with a specific activity of 58Ci/mmol. Copyright © 2001 John Wiley & Sons, Ltd. [source] Glutamate and nitric oxide modulate ERK and CREB phosphorylation in the avian retina: evidence for direct signaling from neurons to Müller glial cellsJOURNAL OF NEUROCHEMISTRY, Issue 2 2009Renato Esteves da Silva Socodato Abstract Glutamate signaling in the mature retinal tissue is very important for accurate sensory decoding by retinal neurons and orchestrates the fine-tuned output from the retina to higher-order centers at the cerebral cortex. In this study, we show that glutamate induces a rapid extracellular-regulated kinase and cAMP-responsive element binding protein (CREB) phosphorylation in cultured developing retinal neurons. This process is reliant on ,-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors and nitric oxide (NO) signaling and independent of NMDA receptors activation, as it is blocked by ,-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate antagonists as well as inhibiting NO synthase with NG-nitro- l -arginine methyl ester but not by the NMDA channel blocker dizocilpine maleate. The effect of NO on extracellular-regulated kinase and CREB is mediated by the classical NO/soluble guanylyl cyclase/protein kinase G pathways as it is inhibited by the soluble guanylyl cyclase blocker 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one and the protein kinase G inhibitor KT5823, respectively. Immunocytochemical data suggest that increased CREB phosphorylation in response to glutamate occurs in glial cell nuclei. We also have supporting evidence suggesting that neuronally produced NO directly reaches the glial cells and stimulates CREB phosphorylation. Hence, the results indicate the importance of neuronal,glial communication and glutamate/NO/CREB linkage during retinal development. [source] Glutamate receptors modulate sodium-dependent and calcium-independent vitamin C bidirectional transport in cultured avian retinal cellsJOURNAL OF NEUROCHEMISTRY, Issue 2 2009Camila Cabral Portugal Abstract Vitamin C is transported in the brain by sodium vitamin C co-transporter 2 (SVCT-2) for ascorbate and glucose transporters for dehydroascorbate. Here we have studied the expression of SVCT-2 and the uptake and release of [14C] ascorbate in chick retinal cells. SVCT-2 immunoreactivity was detected in rat and chick retina, specially in amacrine cells and in cells in the ganglion cell layer. Accordingly, SVCT-2 was expressed in cultured retinal neurons, but not in glial cells. [14C] ascorbate uptake was saturable and inhibited by sulfinpyrazone or sodium-free medium, but not by treatments that inhibit dehydroascorbate transport. Glutamate-stimulated vitamin C release was not inhibited by the glutamate transport inhibitor l -,-threo-benzylaspartate, indicating that vitamin C release was not mediated by glutamate uptake. Also, ascorbate had no effect on [3H] d -aspartate release, ruling out a glutamate/ascorbate exchange mechanism. 2-Carboxy-3-carboxymethyl-4-isopropenylpyrrolidine (Kainate) or NMDA stimulated the release, effects blocked by their respective antagonists 6,7-initroquinoxaline-2,3-dione (DNQX) or (5R,2S)-(1)-5-methyl-10,11-dihydro-5H -dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801). However, DNQX, but not MK-801 or 2-amino-5-phosphonopentanoic acid (APV), blocked the stimulation by glutamate. Interestingly, DNQX prevented the stimulation by NMDA, suggesting that the effect of NMDA was mediated by glutamate release and stimulation of non-NMDA receptors. The effect of glutamate was neither dependent on external calcium nor inhibited by 1,2-bis (2-aminophenoxy) ethane-N,,N,,N,,N,,-tetraacetic acid tetrakis (acetoxy-methyl ester) (BAPTA-AM), an internal calcium chelator, but was inhibited by sulfinpyrazone or by the absence of sodium. In conclusion, retinal cells take up and release vitamin C, probably through SVCT-2, and the release can be stimulated by NMDA or non-NMDA glutamate receptors. [source] 2-Deoxyglucose and NMDA inhibit protein synthesis in neurons and regulate phosphorylation of elongation factor-2 by distinct mechanismsJOURNAL OF NEUROCHEMISTRY, Issue 3 2006M. Maus Abstract Cerebral ischaemia is associated with brain damage and inhibition of neuronal protein synthesis. A deficit in neuronal metabolism and altered excitatory amino acid release may both contribute to those phenomena. In the present study, we demonstrate that both NMDA and metabolic impairment by 2-deoxyglucose or inhibitors of mitochondrial respiration inhibit protein synthesis in cortical neurons through the phosphorylation of eukaryotic elongation factor (eEF-2), without any change in phosphorylation of initiation factor eIF-2,. eEF-2 kinase may be activated both by Ca2+ -independent AMP kinase or by an increase in cytosolic Ca2+. Although NMDA decreases ATP levels in neurons, only the effects of 2-deoxyglucose on protein synthesis and phosphorylation of elongation factor eEF-2 were reversed by Na+ pyruvate. Protein synthesis inhibition by 2-deoxyglucose was not as a result of a secondary release of glutamate from cortical neurons as it was not prevented by the NMDA receptor antagonist 5-methyl-10,11-dihydro-5H-dibenzo-(a,d)-cyclohepten-5,10-imine hydrogen maleate (MK 801), nor to an increase in cytosolic-free Ca2+. Conversely, 2-deoxyglucose likely activates eEF-2 kinase through a process involving phosphorylation by AMP kinase. In conclusion, we provide evidence that protein synthesis can be inhibited by NMDA and metabolic deprivation by two distinct mechanisms involving, respectively, Ca2+ -dependent and Ca2+ -independent eEF-2 phosphorylation. [source] Intracellular glutathione mediates the denitrosylation of protein nitrosothiols in the rat spinal cordJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2009Jorge M. Romero Abstract Protein S-nitrosothiols (PrSNOs) have been implicated in the pathophysiology of neuroinflammatory and neurodegenerative disorders. Although the metabolically instability of PrSNOs is well known, there is little understanding of the factors involved in the cleavage of S-NO linkage in intact cells. To address this issue, we conducted chase experiments in spinal cord slices incubated with S-nitrosoglutathione (GSNO). The results show that removal of GSNO leads to a rapid disappearance of PrSNOs (t½ , 2 hr), which is greatly accelerated when glutathione (GSH) levels are raised with the permeable analogue GSH ethyl ester. Moreover, PrSNOs are stable in the presence of the GSH depletor diethyl maleate, indicating that GSH is critical for protein denitrosylation. Inhibition of GSH-dependent enzymes (glutathione S-transferase, glutathione peroxidase, and glutaredoxin) and enzymes that could mediate denitrosylation (alcohol dehydrogense-III, thioredoxin and protein disulfide isomerase) do not alter the rate of PrSNO decomposition. These findings and the lack of protein glutathionylation during the chase indicate that most proteins are denitrosylated via rapid transnitrosylation with GSH. The differences in the denitrosylation rate of individual proteins suggest the existence of additional structural factors in this process. This study is relevant to our recent discovery that PrSNOs accumulate in the central nervous system of patients with multiple sclerosis. © 2008 Wiley-Liss, Inc. [source] Irsogladine maleate counters the interleukin-1,-induced suppression in gap-junctional intercellular communication but does not affect the interleukin-1,-induced zonula occludens protein-1 levels in human gingival epithelial cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 1 2008T. Fujita Background and Objective:, Irsogladine maleate counters gap junctional intercellular communication reduction induced by interleukin-8 or Actinobacillus actinomycetemcomitans in cultured human gingival epithelial cells. Interleukin-1, is involved in periodontal disease. Little is known, however, about the effect of interleukin-1, on intercellular junctional complexes in human gingival epithelial cells. Furthermore, irsogladine maleate may affect the actions of interleukin-1,. In this study, we examined how interleukin-1, affected gap junctional intercellular communication, connexin 43 and zonula occludens protein-1, and how irsogladine maleate modulated the interleukin-1,-induced changes in the intercellular junctional complexes in human gingival epithelial cells. Material and Methods:, Human gingival epithelial cells were exposed to interleukin-1,, with or without irsogladine maleate. Connexin 43 and zonula occludens protein-1 were examined at mRNA and protein levels by real-time polymerase chain reaction and western blotting, respectively. Gap junctional intercellular communication was determined using the dye transfer method. The expression of zonula occludens protein-1 was also confirmed by immunofluorescence. Results:, Interleukin-1, decreased connexin 43 mRNA levels, but increased zonula occludens protein-1 mRNA levels. Irsogladine maleate countered the interleukin-1,-induced reduction in gap junctional intercellular communication and connexin 43 levels. However, irsogladine maleate did not influence the increased zonula occludens protein-1 levels. Conclusion:, The effect of interleukin-1, on gap junctional intercellular communication and tight junctions of human gingival epithelial cells is different. The recovery of gap junctional intercellular communication by irsogladine maleate in the gingival epithelium may be a normal process in gingival epithelial homeostasis. [source] Self-assembly of drug,polymer complexes: A spontaneous nanoencapsulation process monitored by atomic force microscopy,JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2003Mireia Oliva Abstract Since hydrophilic matrices were proposed for controlled drug delivery, many polymeric excipients have been studied to make drug release fit the desired profiles. It has been pointed out that ,-carrageenan, a sulfated polymer from algae, can suitably control the release rate of basic drugs from hydrophilic matrices. Furthermore, the relevance of hydrophobic interactions in drug,polymer aqueous systems has already been demonstrated, although no references to morphological features as well as to the kinetics of the interaction complexes formation have been published to date. In this work, we propose a method to monitor the topographical evolution of the interaction between ,-carrageenan and dexchlorpheniramine maleate, in order to determine how the release profiles can be so easily controlled. For this purpose, solutions of both polymer and drug were prepared at very low concentration. Solutions were mixed and small volumes were taken every hour for over a period of 24 h and subsequently analyzed. The characterization technique used, atomic force microscopy, provides a high resolution, allowing plotting of three-dimensional images of the sample morphology within the nanometric scale. The results demonstrate that ,-carrageenan is able to nanoencapsulate spontaneously dexchlorpheniramine maleate molecules, which offers the possibility of controlling the release rate of the drug with no need of complex technological processes. Moreover, this work demonstrates the suitability of atomic force microscopy for the specific case of the on-time monitoring of interaction processes that occur in pharmaceutical systems. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:77,83, 2003 [source] | |||||||||||||||||||||||||||||||