Semi-Blind Deconvolution for Resolution Enhancement in Ultrasound Imaging

International audienceIn the field of ultrasound imaging, resolution enhancement is an up-to-date challenging task. Many device-based approaches have been proposed to overcome the low resolution nature of ultrasound images but very few works deal with post-processing methods. This paper investigates a novel approach based on semi-blind deconvolution formulation and alternating direction method framework in order to perform the ultrasound image restoration task. The algorithm performance is addressed using optical images and synthetic ultrasound data for a various range of criteria. The results demonstrate that our technique is more robust to uncertainties in the a priori ultrasonic pulse than classical non-blind deconvolution methods

Amélioration de la résolution des images ultrasonores en mode B par déconvolution semi-aveugle

National audienceEn imagerie médicale, et plus précisément dans le domaine de l'imagerie ultrasonore, les problématiques liées à l'amélioration de la résolution font aujourd'hui l'objet de très nombreux travaux. Alors que beaucoup d'approches se consacrent à l'amélioration du dispositif d'acquisition des images échographiques (pré-traitement) pour pallier leur faible résolution, très peu de travaux se sont attachés à des techniques de post-traitement. Nous proposons ici une nouvelle approche pour la restauration d'image basée sur une formulation de type déconvolution semi-aveugle, résolue dans le cadre algorithmique de la méthode des directions alternées. Les performances de notre algorithme sont évaluées à l'aide de données synthétiques (fantôme de Shepp-Logan) et d'une image ultrasonore in vivo en mode B, sur la base de plusieurs critères quantitatifs. Dans le cas où la réponse impulsionnelle spatiale du système est mal connue, les résultats démontrent une robustesse accrue par rapport à une méthode de déconvolution classique (non aveugle)

CTCF binds the proximal exonic region of hTERT and inhibits its transcription

The expression of the catalytic subunit (hTERT) represents the limiting factor for telomerase activity. Previously, we detected a transcriptional repressor effect of the proximal exonic region (first two exons) of the hTERT gene. To better understand the mechanism involved and to identify a potential repressor, we further characterized this region. The addition of the hTERT proximal exonic region downstream of the hTERT minimal promoter strongly reduced promoter transcriptional activity in all cells tested (tumor, normal and immortalized). This exonic region also significantly inhibited the transcriptional activity of the CMV and CDKN2A promoters, regardless of the cell type. Therefore, the repressor effect of hTERT exonic region is neither cell nor promoter-dependent. However, the distance between the promoter and the exonic region can modulate this repressor effect, suggesting that nucleosome positioning plays a role in transcriptional repression. We showed by electrophoretic mobility shift assay that CCCTC-binding factor (CTCF) binds to the proximal exonic region of hTERT. Chromatin immunoprecipitaion assays confirmed the binding of CTCF to this region. CTCF is bound to hTERT in cells in which hTERT is not expressed, but not in telomerase-positive ones. Moreover, the transcriptional downregulation of CTCF by RNA interference derepressed hTERT gene expression in normal telomerase-negative cells. Our results suggest that CTCF participates in key cellular mechanisms underlying immortality by regulating hTERT gene expression

Eutrophisation en milieu lagonaire : compte-rendu subvention CORDET no 94 T 09

La finalité du programme ANTROPIC est de dresser un bilan des conditions du milieu (eutrophisation, hypersédimentation) dans la zone la plus urbanisée du lagon de Tahiti, de proposer des outils de diagnostic de l'état de l'environnement lagonaire utiles pour la gestion du milie

Étude archéozoologique d’une cour d’habitat sur le site des Barbes-et-Fon-Danis à Saint-Laurent-de-Carnols (Gard, fin Ve s. av. J.‑C. début IVe s. av. J.‑C.)

Les fouilles du site des Barbes-et-Fon-Danis à Saint-Laurent-de-Carnols (Gard) ont livré un assemblage faunique datant de la période de transition entre le premier et le deuxième âge du Fer. Les résultats archéozoologiques issus de cette étude apportent avant tout de nouvelles données sur les modes alimentaires et la gestion des déchets d’origine animale pour la 2nde moitié du Ve et la 1ère moitié du IVe s. av. J.‑C. L’échantillon provient d’une cour aménagée en plein air et témoigne de pratiques alimentaires liées à une consommation exclusivement domestique des habitants installés à proximité de cette cour ayant servi de dépotoir. La faune présente témoigne d’un approvisionnement fondé sur une activité d’élevage avec la présence majoritaire de mammifères domestiques classiques (bœuf, caprinés et porc) associée à une activité cynégétique (cerf et sanglier).The excavation of Barbes-et-Fon-Danis at Saint-Laurent-de-Carnols (Gard, France) has provided a faunal assemblage dated at the transition period between the first and the second Iron Age. This archaeozoological study provides new information on dietary practices and the processing of animal waste during the 5th and 4th centuries BC. The sample comes from a courtyard and shows dietary practices related exclusively to the domestic consumption of the close inhabitants of this courtyard which was used as a rubbish dump. The faunal remains indicate a meat supply mainly based on traditional livestock (cattle, sheep, goat and pig), associated to hunting strategies (red deer and boar)

Avoiding Conflict: The EU Legislative Process in Times of Tension

The current crisis could lead us to expect an overall increase of conflicts in the EU legislative process and eventually a shift from a consensual system to a majoritarian system. This paper aims to assess the evolution of the EU legislative process for the period 1996-2014 and shows that legislative actors still comply with the norm of consensus. We provide explanations for this resilience and analyse its effects. The paper demonstrates that in a context of greater divisions between EU actors, the systematic search for compromise and consensus contributes to modify the legislative regime in the sense of a greater Malthusianism and instability.En raison du contexte de crise, on pourrait s’attendre à ce que le processus législatif européen soit devenu plus conflictuel et à ce que la norme du consensus soit délaissée au profit d’un système majoritaire. Ce cahier tente d’évaluer l’évolution du processus législatif européen pour la période 1996-2014 et montre que les acteurs législatifs suivent encore la norme du consensus. Il tente d’expliquer cette résilience et d’analyser ses effets et montre qu’alors que les tensions entre les acteurs européens se sont accrues, la recherche systématique du compromis et du consensus contribue à modifier le régime législatif en le rendant plus malthusien et instable

Quilamine HQ1-44, an iron chelator vectorized toward tumor cells by the polyamine transport system, inhibits HCT116 tumor growth without adverse effect

International audienceTumor cell growth requires large iron quantities and the deprivation of this metal induced by synthetic metal chelators is therefore an attractive method for limiting the cancer cell proliferation. The antiproliferative effect of the Quilamine HQ1-44, a new iron chelator vectorized toward tumor cells by a polyamine chain, is related to its high selectivity for the Polyamine Transport System (PTS), allowing its preferential uptake by tumoral cells. The difference in PTS activation between healthy cells and tumor cells enables tumor cells to be targeted, whereas the strong dependence of these cells on iron ensures a secondary targeting. Here, we demonstrated in vitro that HQ1-44 inhibits DNA synthesis and cell proliferation of HCT116 cells by modulating the intracellular metabolism of both iron and polyamines. Moreover, in vivo, in xenografted athymic nude mice, we found that HQ1-44 was as effective as cis-platin in reducing HCT116 tumor growth, without its side effects. Furthermore, as suggested by in vitro data, the depletion in exogenous or endogenous polyamines, known to activate the PTS, dramatically enhanced the antitumor efficiency of HQ1-44. These data support the need for further studies to assess the value of HQ1-44 as an adjuvant treatment in cance

Étude archéozoologique d’une cour d’habitat sur le site des Barbes-et-Fon-Danis à Saint-Laurent-de-Carnols (Gard, fin Ve s. av. J.‑C. début IVe s. av. J.‑C.)

Les fouilles du site des Barbes-et-Fon-Danis à Saint-Laurent-de-Carnols (Gard) ont livré un assemblage faunique datant de la période de transition entre le premier et le deuxième âge du Fer. Les résultats archéozoologiques issus de cette étude apportent avant tout de nouvelles données sur les modes alimentaires et la gestion des déchets d’origine animale pour la 2nde moitié du Ve et la 1ère moitié du IVe s. av. J.‑C. L’échantillon provient d’une cour aménagée en plein air et témoigne de pratiques alimentaires liées à une consommation exclusivement domestique des habitants installés à proximité de cette cour ayant servi de dépotoir. La faune présente témoigne d’un approvisionnement fondé sur une activité d’élevage avec la présence majoritaire de mammifères domestiques classiques (bœuf, caprinés et porc) associée à une activité cynégétique (cerf et sanglier).The excavation of Barbes-et-Fon-Danis at Saint-Laurent-de-Carnols (Gard, France) has provided a faunal assemblage dated at the transition period between the first and the second Iron Age. This archaeozoological study provides new information on dietary practices and the processing of animal waste during the 5th and 4th centuries BC. The sample comes from a courtyard and shows dietary practices related exclusively to the domestic consumption of the close inhabitants of this courtyard which was used as a rubbish dump. The faunal remains indicate a meat supply mainly based on traditional livestock (cattle, sheep, goat and pig), associated to hunting strategies (red deer and boar)

BORIS/CTCFL-mediated transcriptional regulation of the hTERT telomerase gene in testicular and ovarian tumor cells

Telomerase activity, not detectable in somatic cells but frequently activated during carcinogenesis, confers immortality to tumors. Mechanisms governing expression of the catalytic subunit hTERT, the limiting factor for telomerase activity, still remain unclear. We previously proposed a model in which the binding of the transcription factor CTCF to the two first exons of hTERT results in transcriptional inhibition in normal cells. This inhibition is abrogated, however, by methylation of CTCF binding sites in 85% of tumors. Here, we showed that hTERT was unmethylated in testicular and ovarian tumors and in derivative cell lines. We demonstrated that CTCF and its paralogue, BORIS/CTCFL, were both present in the nucleus of the same cancer cells and bound to the first exon of hTERT in vivo. Moreover, exogenous BORIS expression in normal BORIS-negative cells was sufficient to activate hTERT transcription with an increasing number of cell passages. Thus, expression of BORIS was sufficient to allow hTERT transcription in normal cells and to counteract the inhibitory effect of CTCF in testicular and ovarian tumor cells. These results define an important contribution of BORIS to immortalization during tumorigenesi