Les BIMEs: un exemple de séquences répétées chez les entérobactéries

Bacterial interspersed mosaic elements (or BIMEs) are repeated sequences identified in several enterobacterial genomes. BIMEs are a mosaic combination of small sequence motifs. It has been estimated that 500 BIMEs are scattered over the bacterial genome. BIMEs have been identified in several enterobacteria: Escherichia coli, Salmonella typhimurium, Klebsiella sp. and relatives of these bacteria. BIME function is not known, but their interactions with specific proteins (DNA polymerase I, gyrase and integration host factor) suggest that they could be involved in functional organization of bacterial chromosomes. Four other families of interspersed repetitive sequences have been shown to exist in a variety of bacterial genomes. Like BIMEs, these sequences are rather small, contain a region of dyad symmetry, and are found in extragenic locations. Unlike BIMEs, IRU (or ERIC), box C sequences and RSA sequences occur in enterobacteria but also in other Gram-negative bacteria.     

Intérêt pronostique de la scintigraphie au 99mTc-MAG3 pour le succès à un an de la transplantation rénale

Because of the increasing use of marginal grafts, it remains a significant difference in terms of transplants half-life between living donor or cadaver donor. The main objective of this study was to assess the prognostic value of various isotopic parameters available on the same day than surgery for the one-year outcome after kidney transplantation. A retrospective study of 100 patients, who received a renal allograft at the University Hospital of Montpellier between 1999 and 2006, and who performed ^99mTc-MAG3 renal scintigraphy within 72 h after transplantation, was performed. Measurement of various isotopic parameters was performed for angiographic and tubular phases, over three different regions of interest. According to judgment criteria, namely the success or not of transplantation after the first year, previously obtained results were statistically compared. The results of our study confirmed the importance of vascular parameters, especially the Kirchner index, with a good correlation with renal function one year after tranplantation. As expected by the physiological models, a well-perfused graft had the most chances of short-term survival. Kirchner index has a negative predictive value of more than 90% for the one-year success after transplantation (VPP = 75%). Parameters assessing more specifically nephronic functional reserve (such as tubular function slope or uptake on perfusion peaks report) are independent risk factors for the failure during the first three months.     

Hérédité et épigénétique: un rôle inattendu pour l’ARN

Although Mendel’s first laws explain the transmission of most characteristics, there has recently been a renewed interest in the notion that DNA is not the sole determinant of our inherited phenotype. Human epidemiology studies and animal and plant genetic studies have provided evidence that epigenetic information (“epigenetic” describes an inherited effect on chromosome or gene function that is not accompanied by any alteration of the nucleotide sequence) can be inherited from parents to offspring. Most of the mechanisms involved in epigenetic “memory” are paramutation events, which are heritable epigenetic changes in the phenotype of a “paramutable” allele. Initially demonstrated in plants, paramutation is defined as an interaction between two alleles of a single locus that results in heritable changes of one allele that is induced by the other. The authors describe an unexpected example of paramutation in the mouse revealed by a recent analysis of an epigenetic variation modulating expression of theKit locus. The progeny of hétérozygote intercrosses (carrying one mutant and one wild-type allele) showed persistence of the white patches (characteristic of hétérozygotes) in the homozygous Kit^+/+ progeny. The DNA sequences of the two wild-type alleles were structurally normal, revealing an epigenetic modification. Further investigations showed that RNA and microRNA, released by sperm, mediate this epigenetic inheritance. The molecular mechanisms involved in this unexpected mode of inheritance and the role of RNA molecules in the spermatozoon head as possible vectors for the hereditary transfer of such modifications — implying that paternal inheritance is not limited to just one haploid copy of the genome — are still a matter of debate. Paramutations may be considered to be one possibility of epigenetic modification in the case of familial disease predispositions not fully explained by Mendelian analysis.     

Les Actinomycoses rénales

Sans résumé     

Les remplissages sédimentaires des coquilles de céphalopodes triasiques. Mécanismes et intérêt paléoécologique

Experiments have been carried out in laboratory onplastic cephalopod models in order to study most aspects of sedimentary shell filling of Ceratites and Nautilus from the German Upper Muschelkalk. In most cases the shells had a horizontal position when being filled by the sediment. The exception of filling in upright position has been observed mainly for Ceratites nodosus nodosus (Bruguière, 1792), Acanthoceratites spinosus (Philippi, 1901) except the species A. spinosus penndorfi (Rothe, 1955), Acanthoceratites evolutus (Philippi, 1901) and the nautilus Germanonautilus bidorsatus (Schlotheim, 1804); it is due to the width of their shells. In no case the sediment filling of cephalopod shells gives information about the depth of the depositional environment. On the other hand it is a good indicator of the waving occurring on the sea floor and the reworking of the sediment.     

Les hyménoptères parasites de la mouche des olives I. Les chalcidiens de la région méditerranéenne

Summary In this brief work, authors study the five Chalcidids parasites of the olivefly in the mediterranean zone and discuss the systematic point of view. They modify the generic name (Cyrtoptyx, Pnigalio) and show the existence of the new speciesP. mediterraneus; this name substitutes the other nameE. longulus Zett which was wrongly given to theDacus's parasite. A table has been done for the rapid identification of the five species of Chalcidids.

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Riassunto Nel presente breve lavoro, gli AA. riprendono lo studio dei cinque Calcididi parassiti della mosca delle olive nella zona mediterranea, ne discutono il valore dal punto di vista sistematico, ne modificano la denominazione generica (Cyrtoptyx, Pnigalio) e mettono in evidenza l'esistenza della nuova specieP. mediterraneus, il cui nome sostituisce quello diE. longulus Zett., erroneamente attribuito al parassita delDacus. E'stata compilata una tabella per l'identificazione rapida di queste cinque specie di Calcididi.

     

Intérêt de la TEP au 18F-FDG préthérapeutique pour prédire la réponse à la radio-immunothérapie dans les lymphomes non hodgkiniens

PurposeRadioimmunotherapy (RIT) is a new treatment option for patients with non-Hodgkin lymphoma (NHL). Response to RIT currently remains difficult to predict using conventional prognostic factors and could be refined using functional imaging. The goal of this work is to evaluate the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting response to yttrium 90-labeled monoclonal antibodies for patients with NHL.MethodThirty-five patients with NHL who had undergone 18F-FDG PET prior to RIT with either 90Y-ibritumomab tiuxetan or 90Y-epratuzumab tetraxetan were included in this retrospective study. Four functional criteria (SUVmax, SUVmean, volume and the product of the volume and the SUVmean-TLG-) were analyzed on a per-lesion basis.ResultsA total of 154 lesions were analysed. The per-lesion analysis revealed significant differences (P < 0.05) between responders and non-responders for several criteria and above all for the SUV.ConclusionOur results suggest a predictive role of 18F-FDG PET prior to RIT by giving a useful indication of the radiosensitivity of the lymphoma.     

Les modalités du percher dans un assemblage de Scarabaeinae de la forêt de Guyane française

Le percher est un comportement répandu chez les espèces d’un assemblage de Scarabaeinae d’une forêt non perturbée de Guyane française. Quarante-trois espèces de percheurs ont été répertoriées sur 7 ans d’échantillonnage. Les fouisseurs diurnes de petite taille (moyenne 7,0 mm) dominaient sur les feuilles isolées et autour des défécations de Singes hurleurs ou des fèces humaines, avec une hauteur moyenne de percher de 62,8 cm. Les hauteurs étaient positivement corrélées aux tailles des insectes excepté pour cinq grandes espèces dont trois possédaient une défense chimique contre les prédateurs. Deux complexes mimétiques ont été identifiés. L’agrégation en dehors de la présence de ressource a été montrée. Les défécations de singes provoquaient une concentration d’insectes dont des Canthon (Glaphyrocanthon) arboricoles qui formaient leurs pilules sur les feuilles. D’autres espèces perchaient en attente de rencontrer au sol un partenaire ou de se livrer au kleptoparasitisme. Les signaux olfactifs pourraient jouer un rôle dans diverses modalités du percher. Compétition et prédation semblent être les principales contraintes auxquelles le percher répond.     

Ciblage peptidique en oncologie nucléaire : intérêt de la modélisation moléculaire

Peptidic receptor targeting in nuclear oncology has been significantly improved the last 20 years. A better in-depth knowledge of peptidic receptor has permitted more extensive research and development of new radioligands. The different published studies showed the interest of radiolabelled peptide development but also the difficulties to obtain a radiopharmaceutical with pharmacologic and pharmacokinetic properties adapted to clinical applications in diagnosis and internal radiotherapy. Based on the literature, the most applied methodology is to modify the structure of the endogenous ligand iteratively and to synthesize various derivatives radiolabelled peptide tested one by one. We chose to address the issue of optimization of radiolabelled peptide analogues from a different recent method via molecular modelling and for our purpose more specifically the targeting of the peptide receptor cholecystokinin/gastrin.     

Histiocytose langerhansienne osseuse multifocale : intérêt de la scintigraphie osseuse planaire

Langerhans cell histiocytosis is a disease of the reticuloendothelial system characterized by a clonal proliferation of dendritic cells of Langerhans. This is a rare disease that primarily affects children and young adults. It can take many forms, from a single eosinophilic granuloma to widespread lesions involving multisystem life-threatening. Bone involvement is the most common, it can be uni- or multifocal. We report a case of multifocal bone Langerhans cell histiocytosis, revealed in a child aged 3 years and touched his left temporal bone and right femur. The bone scintigraphy has found a third location in right scapular. The outcome was favorable after chemotherapy. The bone lesions are characterized by lytic lesions and are responsible for pain, swelling and fractures. All the imaging techniques (radiographs, CT, and MRI) contribute to the formation of the diagnosis. Bone scintigraphy is a very sensitive examination that allows the initial staging and follow-up on treatment of skeletal manifestations.