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Identification of Li+ binding sites and the effect of Li+ treatment on phosphol...
Layden, Brian T.; Abukhdeir, Abde M.; Malarkey, Christopher; Oriti, Lisa A.; Salah, Wajeeh; Stigler, Claire; Geraldes, Carlos F. G. C.Li+ binding in subcellular fractions of human neuroblastoma SH-SY5Y cells was investigated using 7Li NMR spin-lattice (T1) and spin-spin (T2) relaxation measurements, as the T1/T2 ratio is a sensitive parameter of Li+ binding. The majority of Li+ binding occurred in the plasma membrane, microsomes, and nuclear membrane fractions as demonstrated by the Li+ binding constants and the values of the T1/T2 ratios, wh...
Effects of Li+ transport and Li+ immobilization on Li+/Mg2+ competition in cell...
Layden, Brian T.; Abukhdeir, Abde M.; Williams, Nicole; Fonseca, Carla P.; Carroll, Laura; Castro, Margarita M. C. A.; Geraldes, Carlos F. G. C.Li+/Mg2+ competition has been implicated in the therapeutic action of Li+ treatment in bipolar illness. We hypothesized that this competition depended on cell-specific properties. To test this hypothesis, we determined the degree of Li+ transport, immobilization, and Li+/Mg2+ competition in lymphoblastomas, neuroblastomas, and erythrocytes. During a 50 mmol/L Li+-loading incubation, Li+ accumulation at 30 min (...
Evaluation of [Co(gly)3]- as a 35Cl- NMR Shift Reagent for Cellular Studies
Diven, Conrad F.; Wang, Fei; Abukhdeir, Abde M.; Salah, Wajeeh; Layden, Brian T.; Geraldes, Carlos F. G. C.; Freitas, Duarte Mota deWe studied the efficacy of the tris-glycinatocobaltate(II) complex ([Co(gly)3]-) as a shift reagent (SR) for chloride by 35Cl NMR spectroscopy and compared to that of Co2+(aq). Due to the relatively low thermodynamic stability of [Co(gly)3]-, a 1:3 Co(II)/gly stoichiometric solution at physiological pH is approximately a 2:1 mixture of [Co(gly)2(H2O)2] and [Co(gly)(H2O)4]+. This SR was found to be stable up to ...
Li influx and binding, and li/mg competition in bovine chromaffin cell suspensi...
Fonseca, Carlos P.; Montezinho, Liliana P.; Baltazar, Graça; Layden, Brian; Freitas, Duarte M.; Geraldes, Carlos F. G. C.; Castro, M. Margarida C. A.Li(+) influx by bovine chromaffin cells, obtained from bovine adrenal medulla, was studied in intact cell suspensions using (7)Li NMR spectroscopy with the shift reagent [Tm(HDOTP)](4-). The influx rate constants, k(i), were determined in the absence and in the presence of two Na(+) membrane transport inhibitors. The values obtained indicate that both voltage sensitive Na(+) channels and (Na(+)/K(+))-ATPase pla...
Comparison of Fluorescence, 31P NMR, and 7Li NMR Spectroscopic Methods for Inve...
Amari, Louis; Layden, Brian; Rong, Qinfen; Geraldes, Carlos F. G. C.; Freitas, Duarte Mota deThe biochemical action of lithium in the treatment of manic-depressive illness is still unknown. One hypothesis is that Li+ competes for Mg2+-binding sites in biomolecules. We report here our studies on metal ion competition by three distinct methods: fluorescence, 31P NMR, and 7Li NMR spectroscopy, using ATP as a model ligand. By fluorescence spectroscopy, we used the dye, furaptra, by measuring the increases ...
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