RESUMEN
The binary lead fluoride Pb3 F8 was synthesized by the reaction of anhydrous HF with Pb3 O4 or by the reaction of BrF3 with PbF2 . The compound was characterized by single-crystal and powder X-ray diffraction, IR, Raman, and solid-state MAS 19 Fâ NMR spectroscopy, as well as thermogravimetric analysis, XP and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Solid-state quantum-chemical calculations are provided for the vibrational analyses and band assignments. The electronic band structure offers an inside view of the mixed valence compound.
RESUMEN
The erythropoietic effect of recombinant human erythropoietin, epoetin alpha (rHuEPO), in promoting the growth of erythroid burst-forming units (BFU-E) was compared with darbepoetin alpha (DARB), a rHuEPO analogue obtained by site-directed mutagenesis. Human bone marrow cells derived from healthy donors were cultured with different concentrations of rHuEPO or DARB for 12 - 21 days and BFU-E were counted using an inverted microscope. The EC50 of rHuEPO was about 10-fold lower than DARB and the size of the colonies was significantly larger in rHuEPO-containing cultures using comparable concentrations. The maximum number of colonies obtained in some rHuEPO-containing cultures was also higher than for DARB. The number of colonies in DARB-containing cultures was increased, in part, by the addition of low concentrations of rHuEPO, but not by DARB, even at high concentrations. We conclude that DARB is not as effective as rHuEPO in supporting the in vitro growth of human BFU-E.
