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Simultaneous Addition (simultaneous + addition)
Selected AbstractsSimultaneous Determination of Copper and Bismuth by Anodic Stripping Voltammetry Using H-Point Standard Addition Method with Simultaneous Addition of AnalytesELECTROANALYSIS, Issue 17 2005Esmaeil Shams Abstract Simultaneous determination of bismuth and copper by anodic stripping voltammetry using H-point standard addition method (HPSAM) with simultaneous addition of analytes is described. The effect of various parameters including acid concentration, accumulation time, accumulation potential and concentration ratio of analytes in the standard solution on the sensitivity and accuracy of method were investigated. The results of applying the H-point standard addition method showed that Cu2+ and Bi3+ could be determined simultaneously with the concentration ratios of Cu2+ to Bi3+ varying from 1,:,15 to 16,:,1 in the mixed sample. The method was successfully applied to the simultaneous determination of copper and bismuth in some synthetic mixtures. [source] Placenta growth factor stimulates the growth of Philadelphia chromosome positive acute lymphoblastic leukemia cells by both autocrine and paracrine pathwaysEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 4 2005Toshiko Ikai Abstract:, Vascular endothelial growth factor (VEGF) and its associated molecule, placenta growth factor (PlGF) are now known to support normal hematopoiesis, and leukemia cell growth. In this study, expression of VEGF and PlGF in acute lymphoblastic leukemia (ALL) cells was examined by real time reverse transcription-polymerase chain reaction in 20 patient samples. Expression of PlGF was more intense in Philadelphia chromosome positive (Ph+) ALL than in Ph, ALL cases. On the other hand, expression level of VEGF was not different between Ph+ and Ph, cases. Then, PlGF was added to the two ALL cell lines, CRL1929 (Ph+), and Nalm6 (Ph,). The PlGF stimulated the growth of CRL1929 in time- and dose-dependent manners, although the growth of Nalm6 was not affected by PlGF. The growth stimulation of CRL1929 by PlGF was confirmed by the increase of S phase cells. And the growth promoting effect of PlGF on CRL1929 was cancelled by simultaneous addition of VEGFR1/Fc (which binds to PlGF and abrogates its function), but was not cancelled by VEGFR2/Fc (which does not bind to PlGF). Then, addition of VEGFR1/Fc to the simple culture of CRL1929 demonstrated growth inhibitory effect. These observations demonstrated that PlGF stimulates the growth of Ph+ ALL cells by both autocrine and paracrine pathways. Finally, PlGF-VEGFR1 loop might be a therapeutic target to improve the prognosis of Ph+ ALL. [source] Complementation of NADPH oxidase in p67-phox-deficient CGD patientsFEBS JOURNAL, Issue 4 2000p67-phox/p40-phox interaction Chronic granulomatous disease (CGD) is due to a functional defect of the O2, generating NADPH oxidase of phagocytes. Epstein,Barr-virus-immortalized B lymphocytes express all the constituents of oxidase with activity 100 times less than that of neutrophils. As in neutrophils, oxidase activity of Epstein,Barr-virus-immortalized B lymphocytes was shown to be defective in the different forms of CGD; these cells were used as a model for the complementation studies of two p67-phox-deficient CGD patients. Reconstitution of oxidase activity was performed in vitro by using a heterologous cell-free assay consisting of membrane-suspended or solubilized and purified cytochrome b558 that was associated with cytosol or with the isolated cytosolic-activating factors (p67-phox, p47-phox, p40-phox) from healthy or CGD patients. In p67-phox-deficient CGD patients, two cytosolic factors are deficient or missing: p67-phox and p40-phox. Not more than 20% of oxidase activity was recovered by complementing the cytosol of p67-phox-deficient patients with recombinant p67-phox. On the contrary, a complete restoration of oxidase activity was observed when, instead of cytosol, the cytosolic factors were added in the cell-free assay after isolation in combination with cytochrome b558 purified from neutrophil membrane. Moreover, the simultaneous addition of recombinant p67-phox and recombinant p40-phox reversed the previous complementation in a p40-phox dose-dependent process. These results suggest that in the reconstitution of oxidase activity, p67-phox is the limiting factor; the efficiency of complementation depends on the membrane tissue and the cytosolic environment. In vitro, the transition from the resting to the activated state of oxidase, which results from assembling, requires the dissociation of p40-phox from p67-phox for efficient oxidase activity. In the process, p40-phox could function as a negative regulatory factor and stabilize the resting state. [source] Molecular characterization and antifungal activity of a family 46 chitosanase from Amycolatopsis sp.FEMS MICROBIOLOGY LETTERS, Issue 1 2009CsO- Abstract An actinomycete strain, Amycolatopsis sp. CsO-2, produces a 27-kDa chitosanase. To reveal the molecular characteristics of the enzyme, its corresponding gene ctoA was cloned by a reverse genetic technique, based on the N-terminal amino acid sequence of the protein. The encoded CtoA protein was deduced to be composed of 286 amino acids, including a putative signal peptide (1,48), and exhibited 83% identity in the amino acid sequence with the family 46 chitosanases from Streptomyces sp. N174 or Nocardioides sp. N106. The active recombinant CtoA protein was successfully overproduced in Escherichia coli. The mutant protein E22Q, in which the glutamic acid residue 22 was replaced with glutamine, abolished the chitosanase activity, showing that the Glu22 residue is required for the enzymatic activity. CtoA exhibited antifungal activity against Rhizopus oryzae, which is known to produce chitosan probably as a cell wall component. In contrast, E22Q did not inhibit the growth of the fungus, suggesting that chitosan-hydrolyzing activity is essential for the antifungal activity. It is noteworthy that the antifungal effect of CtoA against R. oryzae was drastically enhanced by the simultaneous addition of the family 19 chitinase ChiC from Streptomyces griseus. [source] Different combinations of salts affect the growth and bacteriocin production by Lactobacillus salivarius CRL 1328JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2010María Silvina Juárez Tomás Abstract BACKGROUND: The culture medium for optimal growth of vaginal Lactobacillus salivarius CRL 1328 is different from that for optimal bacteriocin production. To simultaneously obtain high amount of biomass and bacteriocin of this microorganism, the effects of different basal culture media and salts on both responses were evaluated. The study was performed by using a complete factorial experimental design 26, with central points. Sixty-four different growth media, which resulted from the combinations of two basal culture media and two concentrations of five salts (ammonium citrate, sodium acetate, MgSO4, MnSO4, and K2HPO4) were assayed. RESULTS: Only the addition of MnSO4 to each culture medium significantly stimulated the growth of L. salivarius. The presence of sodium acetate or MgSO4 stimulated the bacteriocin production, while MnSO4 and K2HPO4 exerted an inhibitory effect. However, the simultaneous addition of MnSO4 and sodium acetate to both basal culture media allowed high bacteriocin levels to be reached, attenuating the inhibitory effect of Mn2+. CONCLUSIONS: The application of a complete experimental design contributed to simultaneous optimization of the biomass and bacteriocin production of L. salivarius CRL 1328. The results obtained are potentially applicable to the technological production of probiotic bacteria and antagonistic substance to be included in a probiotic pharmaceutical product. Copyright © 2009 Society of Chemical Industry [source] Poster Sessions CP08: Signal TransductionJOURNAL OF NEUROCHEMISTRY, Issue 2002G. Taglialatela Inducible nitric oxide synthase (iNOS) and high levels of nitric oxide (NO) are present in the CNS of patients with Alzheimer's disease (AD), resulting in both DNA and protein oxidative damage. While iNOS can result in damaging levels of NO, the neuronal constitutive form of NOS (nNOS) has a role in cell signalling and can prevent neuronal apoptosis. iNOS can be induced by inflammatory cytokines such as tumor necrosis alpha (TNF,). TNF, is found in the CNS of AD, where neurons dependent on neurotrophins such as nerve growth factor (NGF) are particularly affected. Here we determined the effect of TNF, on the three NOS isoforms (endothelial, neuronal and inducible) in NGF-responsive PC12 cells. We found that while TNF, and NGF alone were uneffective, their simultaneous addition resulted in iNOS induction and the release of NO. In addition TNF, and NGF synergistically reduced nNOS, independently of the presence of high NO levels promoted by iNOS, while no effect was observed on eNOS. A similar pattern was observed in the brain of aged human subjects as compared to young individuals. Our results suggest that synergistic iNOS induction by TNF, and NGF may occur in selective populations of NGF-responsive neurons. Oxidative damage in such neurons could then occur in the presence of elevated levels of TNF,, that potentially occur in the brain of AD patients. This damaging scenario may further be aggravated by a concomitant reduction of nNOS, brought about by similar synergistic effects between TNF, and NGF. Acknowledgements:, Supported by NIA (AG13945) and Sealy Res. Dev. grants to GT. [source] The RhaS activator controls the Erwinia chrysanthemi 3937 genes rhiN, rhiT and rhiE involved in rhamnogalacturonan catabolismMOLECULAR MICROBIOLOGY, Issue 5 2004Nicole Hugouvieux-Cotte-Pattat Summary Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. The linear regions of pectin are composed of an acidic sugar, d -galacturonic acid. The ramified regions of pectin also include neutral sugars, and are rich in l -rhamnose residues. E. chrysanthemi is able to degrade these polysaccharides, polygalacturonate and rhamnogalacturonate. In E. chrysanthemi, the production of pectinases acting on linear regions is induced in the presence of polygalacturonate by a mechanism involving the repressor KdgR. The induction of the two adjacent E. chrysanthemi genes, designated rhiT and rhiN, is maximal after the simultaneous addition of both polygalacturonate and l -rhamnose. The rhiT product is homologous to the oligogalacturonide transporter TogT of E. chrysanthemi. The rhiN product is homologous to various proteins of unknown function, including a protein encoded by the plant-inducible locus picA of Agrobacterium tumefaciens. Both rhiT and rhiN are highly induced during plant infection. Various data suggest that RhiT and RhiN are involved in rhamnogalacturonate catabolism. RhiN is able to degrade the oligomers liberated by the rhamnogalacturonate lyase RhiE. The induction of the rhiTN operon in the presence of polygalacturonate results from control by the repressor KdgR. The additional induction of these genes by rhamnose is directly mediated by RhaS, a protein homologous to the activator of rhamnose catabolism in Escherichia coli. The virulence of an E. chrysanthemi rhaS mutant towards different host plants was clearly reduced. In this phytopathogenic bacterial species, RhaS positively regulates the transcription of the rhaBAD operon, involved in rhamnose catabolism, of the rhiE gene and of the rhiTN operon. The regulator RhaS plays a larger role in E. chrysanthemi than in other enterobacteria. Indeed, the RhaS control is not restricted to the catabolism of rhamnose but is extended to the degradation of plant polysaccharides that contain this sugar. [source] In-line optical detection in the transient state of extrusion polymer blending and reactive processing,,POLYMER ENGINEERING & SCIENCE, Issue 1 2005Tomás Jeferson A. Mélo Using an opticaldetector we followed the transient state of blends and composites, including a reactive blending during extrusion. The detection system is composed of a slit-die with transparent windows fixed at the extruder exit, an optical arrangement with a W incandescent light microbulb with fixed luminescence, and a CdS photocell. As the tracer passes though the light path, it absorbs and backscatters part of the light, reducing the total transmitted light intensity. This is followed by changes in the voltage induced by the photocell to an electric circuit. We calibrated the response of the photocell at room temperature using a set of various films with a second phase dispersed, and obtained a logarithmic relationship. The tracers were particulate (phthalocyanine, TiO2) and polymeric (PS, PA6) phases that absorb and scatter light, producing a residence time distribution (RTD) curvelike trace. Measurements were taken from a twin-screw extruder Werner-Pfleiderer ZSK 30 equipped with K-Tron gravimetric feeders operating at various screw configurations and speeds, and feeding rates. The transient state of PP/PA6 blends can be easily detected optically and recorded using one of the components (either PP or PA6) added as a pulse in a steady-state flow of the other component. With the simultaneous addition of a compatibilizer (polypropylene grafted with acrylic acid (PP-g-AA)) with the PA6, the intensity of the detector signal is substantially increased as a result of the PA6/PP-g-AA reaction. Quantitative off-line infrared spectroscopy of the total amide group corroborated the in-line measurements. These observations suggest that an in-line optical detector may be a fast and simple way to study the flow behavior of blends and composites, including reactive processing. POLYM. ENG. SCI. 45:11,19, 2005. © 2004 Society of Plastics Engineers. [source] Development of a novel process for the biological conversion of H2S and methanethiol to elemental sulfurBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003Jan Sipma Abstract The feasibility of anaerobic treatment of wastewater containing methanethiol (MT), an extremely volatile and malodorous sulfur compound, was investigated in lab-scale bioreactors. Inoculum biomass originating from full-scale anaerobic wastewater treatment facilities was used. Several sludges, tested for their ability to degrade MT, revealed the presence of organisms capable of metabolizing MT as their sole source of energy. Furthermore, batch tests were executed to gain a better understanding of the inhibition potential of MT. It was found that increasing MT concentrations affected acetotrophic organisms more dramatically than methylotrophic organisms. Continuous reactor experiments, using two lab-scale upflow anaerobic sludge bed (UASB) reactors (R1 and R2), aimed to determine the maximal MT load and the effect of elevated sulfide concentrations on MT conversion. Both reactors were operated at a hydraulic retention time (HRT) of about 7 hours, a temperature of 30°C, and a pH of between 7.3 and 7.6. At the highest influent MT concentration applied, 14 mM in R1, corresponding to a volumetric loading rate of about 50 mM MT per day, 87% of the organic sulfur was recovered as hydrogen sulfide (12.2 mM) and the remainder as volatile organic sulfur compounds (VOSCs). Upon decreasing the HRT to 3.5 to 4.0 h at a constant MT loading rate, the sulfide concentration in the reactor decreased to 8 mM and MT conversion efficiency increased to values near 100%. MT conversion was apparently inhibited by the high sulfide concentrations in the reactor. The specific MT degradation rate, as determined after 120 days of operation in R1, was 2.83 ± 0.27 mmol MT g VSS,1 day,1. During biological desulfurization of liquid hydrocarbon phases, such as with liquefied petroleum gas (LPG), the combined removal of hydrogen sulfide and MT is desired. In R2, the simultaneous addition of sodium sulfide and MT was therefore studied and the effect of elevated sulfide concentrations was investigated. The addition of sodium sulfide resulted in enhanced disintegration of sludge granules, causing significant washout of biomass. Additional acetate, added to stimulate growth of methanogenic bacteria to promote granulation, was hardly converted at the termination of the experimental period. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 1,11, 2003. [source] Size-Tunable Highly Luminescent SiO2 Particles Impregnated with Number-Adjusted CdTe NanocrystalsCHEMPHYSCHEM, Issue 4 2010Ping Yang Dr. Abstract Highly luminescent SiO2 particles impregnated with CdTe nanocrystals (NCs) are prepared by a sol,gel procedure. Partial ligand exchange from thioglycolic acid to 3-mercaptopropyltrimethoxysilane (MPS) on the NCs enables retention of the initial photoluminescence (PL) efficiency of the NCs in water, while the simultaneous addition of a poor solvent (ethanol) results in regulated assembly of the NCs through condensation of hydrolyzed MPS. The SiO2 particles thus prepared have, for example, a diameter of 16 nm and contain three NCs each. The PL efficiency of these particles is 40,%, while the initial efficiency is 46,% in a colloidal solution. The redshift and narrowed spectral width in PL observed after impregnation indicate that the concentration of NCs in these nearly reaches the ultimate value (on the order of 1021 particles per liter). The porosity of these particles is investigated by means of N2 adsorption,desorption isotherms. Due to the SiO2 shell, these particles have higher stability in phosphate-buffered saline buffer solution than the initial NCs. Their potential use for labeling in bio-applications is investigated by conjugating biotinylated immunoglobulin G to them by using streptavidin maleimide as linker. Successful conjugation is confirmed by electrophoresis in agarose gel. This preparation method is an important step towards fabricating intensely emitting biocompatible SiO2 particles impregnated with semiconductor NCs. [source] Electroanalytical Determination of Cadmium(II) and Lead(II) Using an Antimony Nanoparticle Modified Boron-Doped Diamond ElectrodeELECTROANALYSIS, Issue 10 2009Kathryn Abstract We report the simultaneous electroanalytical determination of Pb2+ and Cd2+ by linear sweep anodic stripping voltammetry (LSASV) using an antimony nanoparticle modified boron doped diamond (Sb-BDD) electrode. Sb deposition was performed in situ with the analytes, from a solution of 1,mg L,1 SbCl3 in 0.1,M HCl (pH,1). Pb2+ inhibited the detection of Cd2+ during simultaneous additions at the bare BDD electrode, whereas in the presence of antimony, both peaks were readily discernable and quantifiable over the linear range 50,500,,g L,1. [source] | |||||||||||||