Synthesis, characterization and structure of new nitrido bridged Rhenium complexes and new types of inorganic, cationic heterocycles

[ReN(B(C6F5)3){N(SPPh2)2}2] entsteht durch die Reaktion von [ReN{N(SPPh2)2}2] mit B(C6F5)3, unter Bildung einer asymmetrischen Nitridobrücke. Bei der analog durchgefuehrten Umsetzung von [ReN{N(SPPh2)2}2] mit GaCl3 kam es unter Beteiligung des Loesungsmittels CH2Cl2 zur Bildung von [Re(NH){N(SPPh2)2}2]+ [GaCl4]-. Die Reaktion von BBr3 mit der protonierten Vorstufe des Liganden HN(SPPh2)2 bzw. dem sauerstoffhaltigen Analogon HN(OPPh2)2 führte zu neuartigen anorganischen, kationischen heterocyclischen Systemen mit vier verschiedenen Elementen im Ring. Es entstanden die Verbindungen [HN{SPPh2}2BBr2]+ [BBr4]- und [HN{OPPh2}2BBr2]+ [BBr4]-. [HN{SPPh2}2BBr2]+ [BBr4]- zeigt dabei in den 31P-NMR- und 11B-NMR-Spektren ein interessantes temperaturabhängiges Verhalten, was auf ein dynamisches Gleichgewicht zwischen einer offenen und einer geschlossenen Sechsringstruktur hindeutet. Das Ergebnis der Geometrieoptimierung nach dem semi-empirischen AM1-Verfahren vermittelt einen Eindruck über die wahrscheinliche dreidimensionale Struktur der offenen Form von [HN{SPPh2}2BBr2]+ [BBr4]-.[ReN(B(C6F5)3){N(SPPh2)2}2] has been synthesized by the reaction of [ReN{N(SPPh2)2}2] with B(C6F5)3, building an asymmetric nitrido bridge. The reaction which was made analogously with [ReN{N(SPPh2)2}2] and GaCl3 led - under the participation of the solvent CH2Cl2 - to the product [Re(NH){N(SPPh2)2}2]+ [GaCl4]-. The reaction of BBr3 with the precursor of the ligand HN(SPPh2)2 respectively the oxygene containing analogue HN(OPPh2)2 led to new inorganic, cationic heterocyclic systems with four different elements in the ring. The products are [HN{SPPh2}2BBr2]+ [BBr_4]- and [HN{OPPh2}2BBr2]+ [BBr4]-. [HN{SPPh2}2BBr2]+ [BBr4]- shows thereto in the 31P-NMR- and 11B-NMR-spectra an interesting temperature dependent behavior, that leads to the conclusion that there is a dynamic equilibrium between an open (only in solution) and a closed structure (six membered ring). The result of the geometry optimization gives an impression of the probable three-dimensional structure of the open form of [HN{SPPh2}2BBr2]+ [BBr_4]-

Eryptosis: Programmed Death of Nucleus-Free, Iron-Filled Blood Cells

Human erythrocytes are organelle-free cells packaged with iron-containing hemoglobin, specializing in the transport of oxygen. With a total number of approximately 25 trillion cells per individual, the erythrocyte is the most abundant cell type not only in blood but in the whole organism. Despite their low complexity and their inability to transcriptionally upregulate antioxidant defense mechanisms, they display a relatively long life time, of 120 days. This ensures the maintenance of tissue homeostasis where the clearance of old or damaged erythrocytes is kept in balance with erythropoiesis. Whereas the regulatory mechanisms of erythropoiesis have been elucidated over decades of intensive research, the understanding of the mechanisms of erythrocyte clearance still requires some refinement. Here, we present the main pathways leading to eryptosis, the programmed death of erythrocytes, with special emphasis on Ca(2+) influx, the generation of ceramide, oxidative stress, kinase activation, and iron metabolism. We also compare stress-induced erythrocyte death with erythrocyte ageing and clearance, and discuss the similarities between eryptosis and ferroptosis, the iron-dependent regulated death of nucleated blood cells. Finally, we focus on the pathologic consequences of deranged eryptosis, and discuss eryptosis in the context of different infectious diseases, e.g., viral or parasitic infections, and hematologic disorders

Association between nuclear factor of kappa B (NFκB) deficiency and induction of eryptosis in mouse erythrocytes

Apoptosis plays a major role in development, tissue renewal and the progression of degenerative diseases. Studies on various types of mammalian cells reported a pro-apoptotic function of acetylcholinesterase (AChE), particularly in the formation of the apoptosome and the degradation of nuclear DNA. While three AChE splice variants are present in mammals, invertebrates typically express two ache genes that code for a synaptically located protein and a protein with non-synaptic functions respectively. In order to investigate a potential contribution of AChE to apoptosis in insects, we selected the migratory locust Locusta migratoria. We established primary neuronal cultures of locust brains and characterized apoptosis progression in vitro. Dying neurons displayed typical characteristics of apoptosis, including caspase-activation, nuclear condensation and DNA fragmentation visualized by TUNEL staining. Addition of the AChE inhibitors neostigmine and territrem B reduced apoptotic cell death under normal culture conditions. Moreover, both inhibitors completely suppressed hypoxia-induced neuronal cell death. Exposure of live animals to severe hypoxia moderately increased the expression of ace-1 in locust brains in vivo. Our results indicate a previously unreported role of AChE in insect apoptosis that parallels the pro-apoptotic role in mammalian cells. This similarity adds to the list of apoptotic mechanisms shared by mammals and insects, supporting the hypothesized existence of an ancient, complex apoptosis regulatory network present in common ancestors of vertebrates and insects

The specific PKC-α inhibitor chelerythrine blunts costunolide-induced eryptosis

Costunolide, a natural sesquiterpene lactone, has multiple pharmacological activities such as neuroprotection or induction of apoptosis and eryptosis. However, the effects of costunolide on pro-survival factors and enzymes in human erythrocytes, e.g. glutathione and glucose-6-phosphate dehydrogenase (G6PDH) respectively, have not been studied yet. Our aim was to determine the mechanisms underlying costunolide-induced eryptosis and to reverse this process. Phosphatidylserine exposure was estimated from annexin-V-binding, cell volume from forward scatter in flow cytometry, and intracellular glutathione [GSH