Électrochimie dans le carbonate de propylène: I. Oxydation anodique de quelques hydrocarbures aromatiques polynucléaires

In propylene carbonate, the two consecutive one-electron oxidations of the aromatic compounds: 9,10-diphenyl anthracene, perylene and thianthrene are quasi-reversible. The cation radicals formed during the first step are very stable; on the other hand, the dications react very rapidly with nucleophilic species such as water. These results are similar to those obtained in acetonitrile or dichloromethane.     

Chemical Modification of A Vinyl Ester Resin by Acid Anhydrides and Characterization of the Products by l3C NMR

A vinyl ester resin was modified into half ester-acids by reaction with phthalic, maleic, and succinic anhydrides, using pyridine as catalyst. GPC analysis indicated that the reaction proceeds without crosslinking or polymerization. ¹³C-NMR analysis showed that the β-isomer of the vinyl ester resin containing a primary hydroxyl group reacts much more rapidly than the α-isomer with a secondary hydroxyl group.     

Progranulin is expressed within motor neurons and promotes neuronal cell survival

Background

Progranulin is a secreted high molecular weight growth factor bearing seven and one half copies of the cysteine-rich granulin-epithelin motif. While inappropriate over-expression of the progranulin gene has been associated with many cancers, haploinsufficiency leads to atrophy of the frontotemporal lobes and development of a form of dementia (frontotemporal lobar degeneration with ubiquitin positive inclusions, FTLD-U) associated with the formation of ubiquitinated inclusions. Recent reports indicate that progranulin has neurotrophic effects, which, if confirmed would make progranulin the only neuroprotective growth factor that has been associated genetically with a neurological disease in humans. Preliminary studies indicated high progranulin gene expression in spinal cord motor neurons. However, it is uncertain what the role of Progranulin is in normal or diseased motor neuron function. We have investigated progranulin gene expression and subcellular localization in cultured mouse embryonic motor neurons and examined the effect of progranulin over-expression and knockdown in the NSC-34 immortalized motor neuron cell line upon proliferation and survival.

Results

In situ hybridisation and immunohistochemical techniques revealed that the progranulin gene is highly expressed by motor neurons within the mouse spinal cord and in primary cultures of dissociated mouse embryonic spinal cord-dorsal root ganglia. Confocal microscopy coupled to immunocytochemistry together with the use of a progranulin-green fluorescent protein fusion construct revealed progranulin to be located within compartments of the secretory pathway including the Golgi apparatus. Stable transfection of the human progranulin gene into the NSC-34 motor neuron cell line stimulates the appearance of dendritic structures and provides sufficient trophic stimulus to survive serum deprivation for long periods (up to two months). This is mediated at least in part through an anti-apoptotic mechanism. Control cells, while expressing basal levels of progranulin do not survive in serum free conditions. Knockdown of progranulin expression using shRNA technology further reduced cell survival.

Conclusion

Neurons are among the most long-lived cells in the body and are subject to low levels of toxic challenges throughout life. We have demonstrated that progranulin is abundantly expressed in motor neurons and is cytoprotective over prolonged periods when over-expressed in a neuronal cell line. This work highlights the importance of progranulin as neuroprotective growth factor and may represent a therapeutic target for neurodegenerative diseases including motor neuron disease.     

Synthesis and study of block copolycondensates containing polysiloxane and unsaturated polyester blocks in the chain. II. Poly(unsaturated esters-b-siloxanes) with blocks linked by Si?C bonds and poly(butadienes-b-siloxanes)

Poly(unsaturated esters-b-siloxanes) whose blocks are linked by Si? C bonds and poly(butadienes-b-siloxanes) have been obtained by polycondensation of ω,ω′-diepoxy polydimethylsiloxanes and ω,ω′-dicarboxylic poly(unsaturated esters). The reaction between polysiloxanes with Si? H end groups and allylepoxy has been studied; the resulting ω,ω-diepoxy polysiloxanes have the expected structure. The polycondensation of oligomers with, respectively, epoxy and carboxylic end groups has been studied and the optimal conditions established. The samples with Si? C bonds are not affected by hydrolysis in pure water. The poly(siloxanes-b-unsaturated esters) can be cured by UV light.     

Synthesis and characterization of poly(butadiene-b-sulphone) by block-copolycondensation—I. Synthesis from α,ω-dichlorocarbonyl oligobutadienes and α,ω-diphenol oligoarylethersulphones

Synthesis of poly(butadiene-b-sulphone) has been carried out by two methods. Reaction of α,ω-di(sodium phenolate) oligosulphone with α,ω-di(chlorocarbonyl)oligobutadiene or reaction of α,ω-diphenol oligosulphone with α,ω-di(chlorocarbonyl)oligobutadiene in the presence of magnesium. For both methods, the reaction was carried out between two models (bisphenol A and adipoyl chloride) or between a model and an oligomer or between two oligomers. For the first reaction a two-step process, involving the separation and the purification of the phenolate, is described: it is more efficient than the classical one-step process, where acid chloride is added in an alkaline solution of phenol. The second method, which seems never to have been used in polymer synthesis, gives better results than the first, with higher $\text{DP}{}_{\mathrm{n}}$ and less interference from side-reactions.     

Électrochimie dans le carbonate de propylène: II. Utilisation du système Ar+/Ar− des hydrocarbures aromatiques alternés comme référence de potentiel indépendante du solvant

The standard potentials of Ar⁺/Ar and Ar/Ar^? redox couples of some mono- and poly-nuclear aromatic hydrocarbons have been measured in propylene carbonate. It appears that: (a) the difference E⁰(Ar⁺/Ar)?E⁰(Ar/Ar^?) is constant in various solvents for a given hydrocarbon; (b) in a medium, the sum E⁰(Ar⁺/Ar)+E⁰(Ar/Ar^?) is independent of the hydrocarbon. These results confirm that the Ar⁺/Ar^? system can be used as a solvent-independent reference for potential comparisons.     

B(C6F5)3-catalyzed formation of B-P bonds by dehydrocoupling of phosphine-boranes

Tris(pentafluorophenyl)borane was used as a new catalyst in the formation of P-B bonds by dehydrocoupling of phosphine-boranes.