Nutrition in hemodialysis patients previously on a supplemented very low protein diet

Nutrition in hemodialysis patients previously on a supplemented very low protein diet.BackgroundNutritional safety of protein-restricted diets in patients with chronic renal failure is controversial. In the present study, we have assessed the evolution of nutritional status after initiation of hemodialysis in patients previously treated by a supplemented very low protein diet (SVLPD).MethodsNutritional data were prospectively collected during the first year of hemodialysis from 15 consecutive patients treated with a SVLPD (0.3 g protein/kg/day supplemented with essential amino acids, calcium, iron, and vitamins) and compared to 15 age- and gender-matched end-stage renal disease (ESRD) patients previously on a less-restricted diet (0.90 ± 0.21 g protein/kg/day) who started hemodialysis during the same period. Dual-energy x-ray absorptiometry (DEXA) was used to assess body composition at 0, 6, and 12 months. Hemodialysis prescriptions, biologic data and 3-day food records were collected every 3 months.ResultsProtein intake was higher than 1.2 g/kg/day in both groups as soon as 3 months after the start of hemodialysis. Albumin and prealbumin increased significantly during the first 6 months in all patients. Body mass index (BMI) increased in all patients (+0.97 ± 1.31 kg/m2; P < 0.001) reflecting a gain in fat mass in the overall population (+2.36 ± 2.94 kg/m2; P < 0.001) while lean body mass remained stable overall.ConclusionOnce on hemodialysis, SVLPD patients rapidly increased protein intake. Nutritional status improved in all patients, with a gain in fat mass in all, and a gain in lean body mass in SVLPD men only. These data indicate that treatment with a SVLPD prior to hemodialysis initiation is nutritionally safe

5-Hydroxy-5-methylhydantoin DNA lesion, a molecular trap for DNA glycosylases

DNA base-damage recognition in the base excision repair (BER) is a process operating on a wide variety of alkylated, oxidized and degraded bases. DNA glycosylases are the key enzymes which initiate the BER pathway by recognizing and excising the base damages guiding the damaged DNA through repair synthesis. We report here biochemical and structural evidence for the irreversible entrapment of DNA glycosylases by 5-hydroxy-5-methylhydantoin, an oxidized thymine lesion. The first crystal structure of a suicide complex between DNA glycosylase and unrepaired DNA has been solved. In this structure, the formamidopyrimidine-(Fapy) DNA glycosylase from Lactococcus lactis (LlFpg/LlMutM) is covalently bound to the hydantoin carbanucleoside-containing DNA. Coupling a structural approach by solving also the crystal structure of the non-covalent complex with site directed mutagenesis, this atypical suicide reaction mechanism was elucidated. It results from the nucleophilic attack of the catalytic N-terminal proline of LlFpg on the C5-carbon of the base moiety of the hydantoin lesion. The biological significance of this finding is discussed

Iconicity as Recognizability

23 pages, 15 figures. Produit avec Microsoft Word. A paraître dans un numéro spécial de VISIO (revue de l'Association Internationale de Sémiotique Visuelle), « l'iconicité revisitée », édité par Göran Sonesson.We expose a pragmatic view of the iconic sign, getting rid totally of the notion of reference. In communicative contexts (not in Arts), an iconic sign is useful as far as it succeeds in making a reader produce an expected interpretation. So, its essential feature has to reside in the recognizability of a conventional visual type. We illustrate how the visual type - being conventional - is dependent from the target readers population. We show examples of how significant visual features, defining a stereotypical visual sign for a given concept, may be found in corpora of spontaneous drawing productions. Samples are given from a population of 13/14 years old school children.Nous exposons une conception pragmatique du signe iconique qui se débarrasse totalement de la notion de référence. Dans des contextes communicatifs (N.B. ceci n'est pas valable pour l'art), un signe iconique n'est utile qu'en ce qu'il conduit le lecteur à en produire une interprétation conforme aux attentes. Sa propriété la plus fondamentale doit donc consister en la « reconnaissabilité » d'un type visuel conventionnel. Nous illustrons le fait que comme toute convention, le type iconique est dépendant de la population de lecteurs qui est ciblée. Nous donnons des exemples de détection de caractères visuels élémentaires pertinents (qui définissent a minima un stéréotype visuel pour un concept donné) à partir de corpus de productions spontanées de dessins. Des échantillons de corpus recueillis auprès de collégiens de 3e et 4e (système scolaire français, i.e. enfants de 13-14 ans) sont donnés en illustration

The MC1-DNA complex solution structure reveals that a monomeric protein can induce a U-turn in archaea.

International audienc

New protein-DNA complexes in archaea: a monomeric protein induces a U-turn structure.

International audienc

Study of a phase change energy storage using spherical capsules. Part I: Experimental results

International audienc

Model of a DNA-protein complex of the architectural monomeric protein MC1 from Euryarchaea.

In Archaea the two major modes of DNA packaging are wrapping by histone proteins or bending by architectural non-histone proteins. To supplement our knowledge about the binding mode of the different DNA-bending proteins observed across the three domains of life, we present here the first model of a complex in which the monomeric Methanogen Chromosomal protein 1 (MC1) from Euryarchaea binds to the concave side of a strongly bent DNA. In laboratory growth conditions MC1 is the most abundant architectural protein present in Methanosarcina thermophila CHTI55. Like most proteins that strongly bend DNA, MC1 is known to bind in the minor groove. Interaction areas for MC1 and DNA were mapped by Nuclear Magnetic Resonance (NMR) data. The polarity of protein binding was determined using paramagnetic probes attached to the DNA. The first structural model of the DNA-MC1 complex we propose here was obtained by two complementary docking approaches and is in good agreement with the experimental data previously provided by electron microscopy and biochemistry. Residues essential to DNA-binding and -bending were highlighted and confirmed by site-directed mutagenesis. It was found that the Arg25 side-chain was essential to neutralize the negative charge of two phosphates that come very close in response to a dramatic curvature of the DNA

New protein-DNA complexes in archaea: a small monomeric protein induces a sharp V-turn DNA structure

International audienceMC1, a monomeric nucleoid-associated protein (NAP), is structurally unrelated to other DNA-binding proteins. The protein participates in the genome organization of several Euryarchaea species through an atypical compaction mechanism. It is also involved in DNA transcription and cellular division through unknown mechanisms. We determined the 3D solution structure of a new DNA-protein complex formed by MC1 and a strongly distorted 15 base pairs DNA. While the protein just needs to adapt its conformation slightly, the DNA undergoes a dramatic curvature (the first two bend angles of 55° and 70°, respectively) and an impressive torsional stress (dihedral angle of 106°) due to several kinks upon binding of MC1 to its concave side. Thus, it adopts a V-turn structure. For longer DNAs, MC1 stabilizes multiple V-turn conformations in a flexible and dynamic manner. The existence of such V-turn conformations of the MC1-DNA complexes leads us to propose two binding modes of the protein, as a bender (primary binding mode) and as a wrapper (secondary binding mode). Moreover, it opens up new opportunities for studying and understanding the repair, replication and transcription molecular machineries of Archaea

New protein-DNA complexes in archaea: a monomeric protein induces a U-turn structure.

International audienc

Study of a phase change energy storage using spherical capsules. Part II: Numerical modelling

International audienc