Rôle de l'acide ascorbique — besoins,valeur thérapeutique

Sans résumé     

Behaviour of intrinsically disordered proteins in protein–protein complexes with an emphasis on fuzziness

Intrinsically disordered proteins (IDPs) do not, by themselves, fold into a compact globular structure. They are extremely dynamic and flexible, and are typically involved in signalling and transduction of information through binding to other macromolecules. The reason for their existence may lie in their malleability, which enables them to bind several different partners with high specificity. In addition, their interactions with other macromolecules can be regulated by a variable amount of chemically diverse post-translational modifications. Four kinetically and energetically different types of complexes between an IDP and another macromolecule are reviewed: (1) simple two-state binding involving a single binding site, (2) avidity, (3) allovalency and (4) fuzzy binding; the last three involving more than one site. Finally, a qualitative definition of fuzzy binding is suggested, examples are provided, and its distinction to allovalency and avidity is highlighted and discussed.     

Hepatic α-tocopherol binding protein in the rat: Absence of an effect of selenium deficiency on binding activity

Summary Selenium deficiency produces no effect on either the total content of or the binding properties of rat liver -tocopherol binding protein.     

IgG purification to measure the level of an iodinated thyroglobulin peptide,the 3,5,3′,5′ tetraiodo-l-tyrosyl-l-tyrosine in human serum

Summary Antibodies reacting with 3,5,3,5 tetraiodo-l-tyrosyl-l-tyrosine (I₂Tyr-I₂Tyr) were elicited in rabbits by immunization with an oxidized yeast conjugate coupled with I₂Tyr-I₂Tyr. Ion-exchange chromatography was used to purify immunoglobulins, in order to improve the specificity in measurement of I₂Tyr-I₂Tyr level in patient serum. IgG binding capacity versus I₂Tyr-I₂Tyr was considerably increased after immunoglobulin purification.Acknowledgments. The authors with to thank Mrs M. Ollier for her valuable technical assistance.     

Antagonism by haloperidol of the suppression of exploratory locomotor activity induced by the local application of(−)3-(3-hydroxyphenyl)-N-n-propylpiperidine into the nucleus accumbens of the rat

Summary The injection of (–)3-PPP into the nucleus accumbens, 10 g/side, produced a suppression of exploratory locomotor activity without affecting treadmill locomotion. Furthermore, the suppression of exploratory locomotor activity produced by (–)3-PPP was antagonized by the administration of haloperidol, 25–50 g/kg i.p.Acknowledgments. The figures were prepared by M. Kröning at the Department of Psychology, University of Göteborg. This work was supported by Torsten and Ragnar Söderberg's Foundation, Magn. Bergvall Foundation and Åke Wiberg Foundation.     

Levels ofβ-trace protein and lysozyme in human amniotic fluids

Summary The levels of -trace protein and lysozyme were estimated in amniotic fluids from normal fetuses and from fetuses with neuraltube defects. The values of these proteins in normal amniotic fluids were found to be similar to those detected in fetuses with anencephaly and spina bifida. The levels of lysozyme were shown to be correlated with gestational age.     

Is attenuation of tRNA charging responsible for the inhibition of protein labelling accompanying depolarisation of the cerebral cortical cells?

Summary Topical application of concentrated solutions of KCl resulted in reduction of charging of tRNA 7 min after s.c. injection of L-(U-¹⁴C) leucine. Neither radioactivity nor pool size of the total amino acids changed during this period.     

Evolutionary and functional epitopes of the Spätzle protein: New insights into activation of the Toll receptor

Sp?tzle, a dimeric ligand, binds to the Drosophila Toll receptor and activates the signal pathway functioning in both embryonic patterning and innate immunity. Here, we used the evolutionary trace approach based on phylogenetic information to predict the evolutionary epitope of Sp?tzle and found that it mainly clusters in several adjacent loops of Sp?tzle far from the cystine-knot structural domain. We designed six mutants of Sp?tzle based on the evolutionary epitope and transfected them into a stable cell line expressing the luciferase reporter gene under the control of the drosomycin promoter. Luciferase assays showed that these mutants cannot significantly activate the drosomycin promoter, suggesting the involvement of these sites in binding of Sp?tzle to the Toll receptor. These data highlight the importance of the Trp-loop of the mushroom-shaped Sp?tzle dimer in Toll receptor activation and demonstrate that evolution-guided site-specific mutagenesis represents a useful and promising strategy for understanding the ligand-receptor interaction. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 14 January 2009; received after revision 14 February 2009; accepted 09 March 2009     

RNA synthesis in α-amanitin-poisoned rats: Prevention of recovery by inhibition of protein synthesis

Summary The treatment with cycloheximide of rats previously poisoned with -amanitin hinders the recovery of RNA synthesis observed in the liver of rats treated with -amanitin alone. The recovery of RNA synthesis can be ascribed to the capability of poisoned rats to synthesize new RNA-polymerase II.Acknowledgments: We thank ProfessorT. Wieland for the generous gift of -amanitin. This work was supported by grants from C.N.R., Rome, and by Pallotti's legacy for Cancer Research.     

Does the ectodermal proctodaeum participate in the development of the pronephric duct in urodele amphibia?

Zusammenfassung Vom ektodermalen Proctodaeum wächst ein kleiner Divertikel dem Vornierengang entgegen und vereinigt sich mit dessen kaudalem Ende. Einen weiteren Anteil hat das Proctodaeum an der Bildung des Vornierenganges nicht. Zugleich mit dem Proctodaeum invaginiert Material für den Mesonephros, das sich in Zellgruppen entlang dem hinteren Ende des Vornierenganges lagert.     

Poinsinet's Edition of the Naturalis historia (1771–1782) and the Revival of Pliny in the Sciences of the Enlightenment

This paper analyses the revival of Pliny's Naturalis historia within the scientific culture of the late eighteenth and early nineteenth centuries, focusing on a French effort to produce an edition with annotations by scientists and scholars. Between the Renaissance and the early eighteenth century, the Naturalis historia had declined in scientific importance. Increasingly, it was relegated to the humanities, as we demonstrate with a review of editions. For a variety of reasons, however, scientific interest in the Naturalis historia grew in the second half of the eighteenth century. Epitomizing this interest was a plan for a scientifically annotated, Latin-French edition of the Naturalis historia. Initially coordinated by the French governmental minister Malesherbes in the 1750s, the edition was imperfectly realized by Poinsinet a few decades later. It was intended to rival two of the period's other distinguished multi-volume books of knowledge, Diderot and D'Alembert's Encyclopédie and Buffon's Histoire naturelle, to which we compare it. Besides narrating the scientific revival of the Historia naturalis during this period, we examine its causes and the factors contributing to its end in the first half of the nineteenth century.     

The effect of γ-irradiation on the amount of 5-hydroxytryptamine in the gut and spleen in the early phase after irradiation

Résumé 24 et 48 h après irradiation- (900 r) la quantité de 5-hydroxytryptamine dans l'intestin du rat n'a pas changé de manière significative. La quantité de 5-hydroxytryptamine dans la rate du rat, exprimée par g de tissu frais a augmenté. Le prétraitement avec de la cystéamine abaisse nettement la quantité de 5-hydroxytryptamine dans la rate, après l'irradiation.     

The motion of the moon in the Romaka Siddhānta

Summary Formulae are fitted to the different sets of values, given by the translators, for the equation of centre for the motion of the moon according to the Romaka Siddhnta, as found in the Pañcasiddhntik of Varha Mihira.