Effect Of Ethylene Glycol-bis Research Articles

Selectivity enhancement of Arsenazo(III) reagent towards heavier lanthanides using polyaminocarboxylic acids: A spectrophotometric study

A new study has been conducted to quantify lanthanide(III) ions using Arsenazo III–polyaminocarboxylic acid (PACA) system. The study disclosed two different analytically important information: (i) λmax of lanthanide–Arsenazo III complexes for lighter lanthanides like Ce(III) and Nd(III) did not shift from its original position on addition of PACA and (ii) for heavier lanthanides like Dy(III), Tm(III) and Lu(III) a new λmax at 538nm was observed, while wavelengths at 610nm and 654nm were disappeared in presence of ethylenediaminetertracetic acid (EDTA) and trans-1,2-Diaminocyclohexane-N,N,N′,N′-tetraacetic acid (DCTA), further the intensity of peak decreased with increase in lanthanide(III) ion concentration. Effect of ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA) and N-(2-hydroxyethyl) ethylenediamine-N,N′,N′-triacetic acid (EDTA-OH) on Arsenzo(III)–Ln(III) complex is very weak and there is no analytically importance of such interaction. Moreover, this work confirms that Nd(III) and heavy lanthanides can be successfully determined with high accuracy in the working range of concentration of these metal ions.

Effect of ethylene glycol-bis(2-aminoethylether)- N, N, N′, N′-tetraacetic acid (EGTA) on the growth, stabilization and morphology of silver nanoparticles

The effect of ethylene glycol-bis(2-aminoethylether)- N, N, N′, N′-tetraacetic acid (EGTA) in stabilizing different shapes of silver nanoparticles have been examined by electronic absorption spectroscopy and transmission electron microscopy. The silver nanoparticles were prepared by two methods, i.e. γ-irradiation and chemical reduction method. Two types of effects of EGTA were identified which lead to the formation of truncated triangular silver nanoplates and chain—like silver aggregates respectively. Time-dependent infrared attenuated total reflectance (ATR-FTIR) studies showed that the nature of adsorption of EGTA on the silver nanoparticle surface influences the shape of the nanoparticles. Pulse radiolysis studies showed the mechanism of formation of the initial silver nanoclusters.

Nongenomic effects of androstenedione on human granulosa luteinizing cells.

This study examines rapid (5-60 s) effects of androgens on the cytosolic free Ca2+ concentration ([Ca2+]i) in human granulosa lutenizing cells. Cells were obtained from human preovulatory follicles, and [Ca2+]i was measured with the use of the Ca(2+)-responsive fluorescent dye fluo-3. Molar concentrations between 100 pmol/L and 1 mumol/L androstenedione increased [Ca2+]i within 5 s after addition to cells. This [Ca2+]i increase resulted from both Ca2+ influx, as shown by the effects of ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and the voltage-dependent Ca2+ channel blocker verapamil, and Ca2+ mobilization from the endoplasmic reticulum, as shown by the effects of thapsigargin. Treatment with pertussis toxin and U-73,122, a specific inhibitor of phospholipase C, abolished the effects of androstenedione on [Ca2+]i. Flutamide, a nuclear androgen receptor antagonist, did not block the increase in [Ca2+]i induced by androstenedione. Testosterone (100 pmol/L to 1 mumol/L) had no effect. This is the first report showing that androstenedione increases [Ca2+]i in granulosa cells. These data provide evidence for the presence in granulosa cells of a novel, short term mechanism of androstenedione action involving voltage-dependent Ca2+ channels in the plasma membrane and phospholipase C activation via a pertussis toxin-sensitive G protein.

Inhibition of In Vitro Meningioma Proliferation after Growth Factor Stimulation by Calcium Channel Antagonists

We have previously reported that calcium channel antagonists can block both the growth of meningiomas in culture and the potent growth stimulation of meningioma cells by epidermal growth factor (EGF) and platelet-derived growth factor (PDGF). This study further defines the nature of this growth inhibition. Primary meningioma cultures were established, and cells were characterized. Fibroblast growth factor or insulin-like growth factor-I growth stimulation in the presence of calcium channel antagonists was examined. In addition, the effects of ethylene glycol-bis-(aminoethylether) N,N,N',N"-tetraacetic acid and Bay K 8644, a calcium channel agonist, on the growth factors were analyzed. Growth factor receptor immunohistochemistry was performed on the original tumors and the in vitro meningioma cells. Twelve of 17 (71%) meningiomas in this study were positive for the EGF receptor, and 14 of 17 (82%) were positive for the PDGF receptor. Five of six (83%) of the culture cells were positive for the EGF receptor, and four of five (80%) were positive for the PDGF receptor. Intracellular calcium changes were quantified using the intracellular calcium-chelating, fluorescent dye, Fura-2. The growth stimulation of fibroblast growth factor and insulin-like growth factor-I on meningioma cells in culture was decreased in a dose-dependent manner by calcium channel antagonists. The growth stimulation of fibroblast growth factor and insulin-like growth factor-I was not affected by a reduction of extracellular calcium, whereas the growth stimulation of EGF and PDGF was. Interestingly, intracellular calcium was not increased after exposure to growth factors but was increased after serum stimulation. This increase could be blocked by preincubation with verapamil. Calcium channel antagonists can inhibit proliferation of meningioma cells in culture after stimulation with a number of growth factors. These drugs might disrupt intracellular calcium homeostasis or interfere with key elements of the growth factor signal transduction pathways. These mechanisms as well as the potential clinical relevance of these findings are discussed.

Specific induction of Ca2+ transport activity in MATa cells of Saccharomyces cerevisiae by a mating pheromone, alpha factor.

Incubation with a high concentration of a mating pheromone, alpha factor, of Saccharomyces cerevisiae induced the accumulation of Ca2+ ion in MATa cells, but not in MAT alpha or MATa/alpha cells, after a lag of 30-40 min. The alpha factor did not cause a nonspecific lesion of the membrane barrier, but induced Ca2+ transport activity specifically. This induction of Ca2+ transport activity correlated with formation of a projection on the cells, or with localized cell elongation, but not with G1 arrest or agglutinin induction. The increased Ca2+ transport activity was maintained only in the continuous presence of a high concentration of alpha factor and de novo protein synthesis. Kinetic studies of induction of Ca2+ transport by alpha factor and effects of ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and Ca2+ ionophore, A23187, on mating suggested an essential role of this physiological reaction in the initiation of sexual conjugation.

Reversible phosphorylation and dephosphorylation of the 20,000-dalton light chain of myosin during the contraction-relaxation-contraction cycle of arterial smooth muscle.

The myosin light chain of intact arterial smooth muscle displayed a cyclic phosphorylation-dephosphorylation and rephosphorylation in consort with contraction, followed by relaxation, followed by a second contraction of the muscle. Application of pharmacological contractile agonists and antagonists of vascular smooth muscle revealed that the level of light chain phosphorylation is related to the contractile state of the muscle. The central role of Ca2+ in regulation of light chain phosphorylation was shown by the effect of ethylene glycol bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA) in inhibiting contraction and light chain phosphorylation and in inducing relaxation and light chain dephosphorylation. Furthermore, studies with antipsychotic drugs, inhibitors of calmodulin, suggested that the Ca2+-dependent regulatory protein is intimately involved in both light chain phosphorylation and contraction of intact smooth muscle. In addition to the myosin light chain, several other proteins were also found to be phosphorylated in intact smooth muscle.

Is there a plasma membrane-located anion-sensitive ATPase? III. Identity of the erythrocyte enzyme with ( [formula omitted

The characteristics of the anion-sensitive Mg 2+-ATPase activity of the rabbit erythrocyte have been studied in a lyophilized ghost preparation. The enzyme appears to be different from the anion-sensitive Mg 2+-ATPase activity of other tissues in many parameters, such as optimal pH, effects of various anions, oligomycin sensitivity and effects of Triton X-100. The enzyme is insensitive towards inhibition by irreversibly bound 4,4′-diisothiocyano-dihydrostilbene-2,2′-disulfonic acid (H 2DIDS). This excludes a relationship between the enzyme and the “band 3” protein, which is thought to be involved in the anion exchange over the erythrocyte membrane. From the effects of ethyleneglycol-bis-(β-aminoethylether)-N,N′- tetraacetic acdi (EGTA), CaCl 2, chlorpromazine and ruthenium red it is concluded that the enzyme activity does not represent a separate entity but is part of the ( Ca 2+ + Mg 2+)-ATPase system of the erythrocyte membrane. A reported stimulatory effect of carbonic anhydrase is attributed to a contamination of the carbonic anhydrase preparation by calcium and/or ( Ca 2+ + Mg 2+)-ATPase activator protein.