Shedding of phosphatidylserine from developing erythroid cells involves microtubule depolymerization and affects membrane lipid composition.

Phosphatidylserine (PS), which is normally localized in the cytoplasmic leaflet of the membrane, flip-flops to the external leaflet during aging of, or trauma to, cells. A fraction of this PS undergoes shedding into the extracellular milieu. PS externalization and shedding change during maturation of erythroid cells and affect the functioning, senescence and elimination of mature RBCs.

Distribution and shedding of the membrane phosphatidylserine during maturation and aging of erythroid cells.

Maturation and aging of erythroid cells are accompanied by extensive remodeling of the membrane and a marked decrease in cell size, processes that are mediated by externalization and shedding of phosphatidylserine (PS). In the present study, we investigated the redistribution of PS in the plasma membrane of erythroid precursors during their maturation and of mature RBCs during senescence, and the involvement of changes in calcium (Ca)-flux in these processes. Maturation was studied by analyzing normal human bone marrow cells as well as cultured human normal erythroid precursors induced by erythropoietin and murine erythroleukemia cells induced by hexamethylene-bisacetamide.

Oxidative stress-induced membrane shedding from RBCs is Ca flux-mediated and affects membrane lipid composition.

Phosphatidylserine (PS), which is normally localized in the cytoplasmic leaflet of the membrane, undergoes externalization during aging or trauma of red blood cells (RBCS: ). A fraction of this PS is shed into the extracellular milieu. Both PS externalization and shedding are modulated by the oxidative state of the cells.

A flow cytometry approach for quantitative analysis of cellular phosphatidylserine distribution and shedding.

Phospholipids are asymmetrically distributed across the membrane of all cells, including red blood cells (RBCs). Phosphatidylserine (PS) is mainly localized in the cytoplasmic membrane leaflet, but during RBC ageing it flip-flops to the external leaflet--a process that is increased in certain pathological conditions (e.g.

Oxidative stress causes membrane phospholipid rearrangement and shedding from RBC membranes--an NMR study.

Nuclear Magnetic Resonance (NMR) spectroscopy was used to investigate the relationship between oxidative stress experienced by RBCs and their phospholipid content and shedding. Using 1H-NMR, we demonstrated a higher lactate/pyruvate ratio, an indicator of oxidative stress, in normal RBCs treated with oxidants (t-butylhydroxyperoxide and H2O2) as well as in beta-thalassemic RBCs. Using 31P-NMR, we found 30% more phosphatidylcholine (PC), and unexpectedly, 35% less phosphatidylserine (PS) in the thalassemic RBCs.

The trans labilization of cis-[PtCl2(13CH3NH2)2] by glutathione can be monitored at physiological pH by [1H,13C] HSQC NMR.

In order to monitor the trans labilization of cisplatin at physiological pH we have prepared the complex cis-[PtCl(2)((13)CH(3)NH(2))(2)] and studied its interactions with excess glutathione in aqueous solution at neutral pH by two-dimensional [1H,13C] heteronuclear single-quantum correlation (HSQC) NMR spectroscopy. [1H,13C] HSQC spectroscopy is a good method for following the release of (13)CH(3)NH(2) but is not so good for characterizing the Pt species in solution. In the reaction of cisplatin with glutathione, Pt-S bonds are formed and Pt-NH(3) bonds are broken.

Preparation, cytotoxicity and interactions with nucleophiles of three isomeric transplatinum complexes containing methylpiperidine ligands.

Three isomeric complexes, trans-[PtCl2(NH3)(2-methylpiperidine)], trans-[PtCl2(NH3)(3-methylpiperidine)] and trans-[PtCl2(NH3)(4-methylpiperidine)], were prepared and their cytotoxicities against six ovarian cancer cell lines, three sensitive and three resistant to cisplatin, were measured. There were no significant differences in the cytotoxicities of the three isomers against these cell lines. The interactions of the three complexes with reduced glutathione (GSH) and with ubiquitin (Ub), as a model protein, were studied.