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  • Life and Medical Sciences  (2)
  • Folate compounds  (1)
  • Ruthenium–Platinum binary oxides  (1)
  • anion stimulation  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Hypochlorite generation on Ru–Pt binary oxide for treatment of dye wastewater (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 1043-1051 
    Details
    ISSN: 1572-8838
    Keywords: dye wastewater ; hypochlorite production ; Ruthenium–Platinum binary oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ruthenium–platinum binary oxides [(Ru + Pt)O x ] were coated on titanium substrates by thermal decomposition. The surface morphologies and elemental analyses of these electrodes were examined by means of scanning electron microscopy. The electrochemical behaviour was characterized by cyclic voltammetry (CV) and linear scanning voltammetry (LSV). The effects of electrolyte conditions on the current efficiency (CE) of hypochlorite production on binary (Ru + Pt)O x electrodes and the treatment of a high salt-containing dye wastewater using this hypochlorite were also investigated. The highest CE for hypochlorite production occurred on the RP1 (20 mol% Pt in precursor) electrode. The major factors influencing CE for hypochlorite production were the electrolyte flow rate, current density and chloride ion (C1−) concentration. The RP1 electrode exhibited the best removal of organics and chromophoric groups in the dye wastewater. On this electrode, better removal of organics and chromophoric groups was obtained at 300 mA cm−2. The colour of black–red dye wastewater became light yellow when a charge of 13.2 A h was passed while the COD of the wastewater decreased from 10 500 to 1250 mg L−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004038503410
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  • 2
    Electronic Resource
    Electronic Resource
    Interaction between anions and the reduced folate/methotrexate transport system in L1210 cell plasma membrane vesicles: Directional symmetry and anion specificity for differential mobility of loaded and unloaded carrier (1984)
    Springer
    The journal of membrane biology 79 (1984), S. 285-292 
    Details
    ISSN: 1432-1424
    Keywords: folate analog transport ; anion stimulation ; vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effect of various anions on the mediated influx and efflux of [3H]methotrexate by L1210 cell plasma membrane vesicles in a HEPES buffer system was studied. Our results show that flux is stimulated to the same extent in either direction when SO4, Pi, or folate compounds (1,L5-CHO-folate-H4, methotrexate), but not Cl− was present in the opposite compartment. This implies the property of directional symmetry, a condition in which differential mobility of loaded and unloaded carriers occurs in both directions.We also observed a similarity in the specificity of the interaction between various anions and carrier in each orientation of the membrane, in the order, Cl− ≪ Pi ≊ SO 4 2− ≪ methotrexate 〈 1,L5-CHO-folate-H4. Also, the absolute differential in mobility of loaded and unloaded carrier (assumed from the extent of transstimulation obtained) varied substantially among the anions examined. No stimulation was obtained with Cl−, and stimulation was twofold with Pi, SO 4 2− and methotrexate and fourfold with 1,L5-CHO-folate-H4. Transstimulation of flux from either external or internal compartment only occurred when a positive gradient of total anions was maintained in the opposite compartment. Also, no stimulation occurred when the same equivalence of two different anions are present in opposing compartments. The concentration of anions required to transstimulate [3H]methotrexate influx was increased four- to 10-fold when vesicles were equilibrated in 145mM NaCl. These results suggest that under physiological conditions, concentrative uptake of methotrexate in intact L1210 cells as a result of anion exchange would require a large positive gradient in the total concentration of internalized anions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871067
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  • 3
    Electronic Resource
    Electronic Resource
    Relationships between carrier-mediated transport of folate compounds by L1210 leukemia cells: Evidence for multiplicity of entry routes with different kinetic properties expressed in plasma membrane vesicles (1983)
    Springer
    The journal of membrane biology 75 (1983), S. 11-20 
    Details
    ISSN: 1432-1424
    Keywords: Folate compounds ; transport multiplicity L1210 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Various independent kinetic criteria for indicating multiplicity of carrier-mediated entry of folate compounds into L1210 cell plasma membrane vesicles are studied. We find a marked inconsistency between values for influxK m andK ix in reciprocal experiments measuring competition between various folate compounds as well as inconsistent effects of transloading shown for 5-formyltetrahydrofolate influx, but not folic acid influx. These results argue strongly against a one-carrier model for transport of folate compounds. The most straightforward interpretation of our data is that two distinct transport systems mediate entry of folate compounds in L1210 plasma membrane vesicles. If a two-carrier model is correct, then our data indicate that one of the carriers has low capacity and high affinity for folate coenzymes and methotrexate. This system is apparently negligible as a transport route for folic acid. Transtimulation of initial influx by substrates of the low capacity system is obtained following transloading with coenzymes but not by transloading with folic acid. Our data indicate that the second folate transport system postulated by the two-carrier model has a low affinity for all the folate compounds studied. Nevertheless, the putative second system is significant, especially for folic acid transport, because it has a much higher capacity than the first transport system. In contrast to the first system, transloading with any of the folate compounds studied had no effect on initial influx mediated by the second folate transport system. The two systems are also differentially inhibited bypCMBS, DIDS and SITS and the influxV max for the high-affinity/low-capacity system was altered in a vesicle preparation derived from a methotrexate resistant L1210 cell line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870795
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  • 4
    Electronic Resource
    Electronic Resource
    Altered molecular properties of tubulin in a multidrug-resistant variant of Chinese hamster cells selected for resistance to vinca alkaloids (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 136 (1988), S. 341-347 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The basis for the markedly altered intracellular binding of [3H]vincristine in a multidrug-resistant variant (DC-3F/VCRd-5L) of Chinese hamster lung cells (DC-3F) was investigated. Binding of [3H]vincristine by protein in cytosol derived from each cell type exhibited a differing requirement for GTP in MgCl2 containing buffer of low-ionic strength. Binding of [3H]vincristine occurred to cytosolic protein derived from both variant and parental DC-3F cells, but after removal of GTP, binding only occurred to cytosolic protein from parental cells regardless of the presence of added GTP. Although binding by cytosolic protein from parental DC-3F cells did not require GTP, the addition of 0.1 mM GTP increased by two-fold the rate and extent of binding. When cytosol from variant and parental DC-3F cells was incubated with low concentrations of [3H]vincristine in high-ionic strength buffer and analyzed by molecular-sieve HPLC, most of the protein binding [3H]vincristine in parentally derived cytosol eluted as Mr 110,000-115,000 daltons, corresponding to that for dimeric tubulin. The same binding species was not detected in cytosol derived from variant cells. However, these same fractions derived with both parental and variant cytosols contained tubulin as shown by SDS-PAGE and immunoblotting. A smaller peak of [3H]vincristine binding and an amount of tubulin equal to that found in later fractions were found in the void volume during the same HPLC elution runs with cytosol from both variant and parental DC-3F cells. Evidence was also obtained for differences between parental and variant DC-3F cells in β-tubulin isoforms following isoelectric focusing and immunoblotting. Parental-cell cytosol contains a single isoform of β-tubulin. However, in variant cell cytosol the same isoform and, in addition, three more basic isoforms were found. These alterations in [3H]vincristine binding and in isoform compositions of β-tubulin in variant versus parental DC-3F cells may have importance in regard to vincristine resistance in DC-3F cells.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041360218
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  • 5
    Electronic Resource
    Electronic Resource
    Markedly altered membrane transport and intracellular binding of vincristine in multidrug-resistant Chinese hamster cells selected for resistance to vinca alkaloids (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 126 (1986), S. 266-274 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Studies of a multidrug-resistant variant (DC-3F/VCRd-5L) of Chinese hamster lung cells selected for resistance to vinca alkaloids revealed marked alterations in transport and intracellular binding of [3H]vincristine compared to parental DC-3F cells. Influx of [3H]vincristine in DC-3F cells appears to be an equilibrating, but mediated, process. Although saturation kinetics for [3H]vincristine influx were not demonstrated, an extremely high temperature-dependence (Q1027-37°C = 5-6) and trans-inhibition of influx following preloading of cells with nonradioactive vincristine argue in favor of a carrier-mediated process. Efflux of [3H]vincristine from parental cells conformed to first-order kinetics (t1/2 37° = 3.6 ± 0.4) and exhibited a lower temperature-dependence (Q10 27-37°C = 3-3.5) than influx. In variant vs. parental cells, influx of [3H]vincristine was reduced 24-fold and efflux was increased twofold, accounting for the large (approximately 48-fold) reduction in steady-state level of exchangeable drug accumulating in variant cells. Otherwise, transport of [3H] vincristine in these cells showed characteristics similar to parental DC 3F cells. Also, the rate and amount of intracellular binding of [3H]vincristine in variant cells was almost 40-fold lower than in parental cells. These alterations in influx and efflux of [3H]vincristine and its intracellular binding appear to account, at least to a major extent, for the high level of resistance (2,750-fold) of this variant to vinca alkaloids. In contrast, cross-resistance of this variant to daunomycin (178-fold) could be explained only minimally by a transport alteration. Only a two-fold increase in efflux of [3H]daunomycin was demonstrated in variant vs. parental cells along with some decrease in intra-cellular binding. Influx of [3 H]daunomycin was unaltered. In view of these results, we conclude that these two agents most likely do not share the same route for entry in these cells but might share the same efflux route.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041260217
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