82 research outputs found
Microvascular density and hypoxia-inducible factor pathway in pancreatic endocrine tumours: negative correlation of microvascular density and VEGF expression with tumour progression
Tumour-associated angiogenesis is partly regulated by the hypoxia-inducible factor (HIF) pathway. Endocrine tumours are highly vascularised and the molecular mechanisms of their angiogenesis are not fully delineated. The aim of this study is to evaluate angiogenesis and expression of HIF-related molecules in a series of patients with pancreatic endocrine tumours (PETs). The expression of vascular endothelial growth factor (VEGF), HIF-1α, HIF-2α and carbonic anhydrase 9 (CA9) was examined by immunohistochemistry in 45 patients with PETs and compared to microvascular density (MVD), endothelial proliferation, tumour stage and survival. Microvascular density was very high in PETs and associated with a low endothelial index of proliferation. Microvascular density was significantly higher in benign PETs than in PETs of uncertain prognosis, well-differentiated and poorly differentiated carcinomas (mean values: 535, 436, 252 and 45âvesselsâmmâ2, respectively, P<0.0001). Well-differentiated tumours had high cytoplasmic VEGF and HIF-1α expression. Poorly differentiated carcinomas were associated with nuclear HIF-1α and membranous CA9 expression. Low MVD (P=0.0001) and membranous CA9 expression (P=0.0004) were associated with a poorer survival. Contrary to other types of cancer, PETs are highly vascularised, but poorly angiogenic tumours. As they progress, VEGF expression is lost and MVD significantly decreases. The regulation of HIF signalling appears to be specific in pancreatic endocrine tumours
"Ostinato" de Louis-RenĂ© des ForĂȘts, une autobiographie paradoxale
Paru en 1997, vingt ans aprĂšs le dernier rĂ©cit de Louis-RenĂ© des ForĂȘts (« Dans un miroir »), "Ostinato" rĂ©unit des fragments autour dâun projet autobiographique paradoxal. Le premier paradoxe rĂ©side dans le contrat que lâouvrage passe avec le lecteur : lâavertissement de lâĂ©diteur place ce dernier en face dâun livre nouveau et pourtant ni inĂ©dit, ni achevĂ© â la construction dâ"Ostinato" offrant un dĂ©menti flagrant Ă lâaffirmation quâil est non organisĂ©. Lâabsence de cohĂ©rence, explicitement donnĂ©e par lâauteur comme Ă©chec au projet autobiographique, est liĂ©e au caractĂšre Ă©pars et discontinu des fragments rĂ©unis. Le rapport du sujet de lâĂ©nonciation avec la troisiĂšme personne, ce il sujet de lâĂ©noncĂ©, est fait de tensions contradictoires, allant de la reconnaissance dâune identitĂ© Ă lâaffirmation dâune altĂ©ritĂ© radicale. Le prĂ©sent, temps majoritairement utilisĂ©, actualise le passĂ© comme un prĂ©sent incomprĂ©hensible et Ă©piphanique, non soumis Ă une reconstruction a posteriori. Lâesprit du paradoxe, qui se manifeste dans des structures syntaxiques privilĂ©giĂ©es (antithĂšse ou chiasme, retournement et opposition), apparaĂźt aussi Ă travers la prĂ©sence dâun je polyphonique soumis au harcĂšlement de ses voix intĂ©rieures. Lâautobiographe, pris en tenaille entre le souci de remĂ©moration et la mise en question de lâactivitĂ© mĂ©morielle, exprime sous la forme du doute sa douloureuse luciditĂ©. Le dĂ©doublement de lâĂ©crivain â qui Ă©crit et se regarde Ă©crire â doit ĂȘtre mis en relation avec lâexpĂ©rience du deuil et avec la difficultĂ© Ă rendre compte du choc du malheur qui sâabat sur lâhomme et le prive de parole : ce choc ne peut sâexprimer â paradoxe de plus â quâau moment oĂč la douleur fulgurante parvient Ă sâapaiser. La tentation du silence devient alors nostalgie dâun horizon perdu ; indispensable Ă lâactivitĂ© de remĂ©moration, le langage est placĂ© au centre de la quĂȘte du sujet. Enfin, cet art du paradoxe, retors et sophistiquĂ©, est Ă©galement au service dâun message ni contradictoire, ni paradoxal, Ă destination du lecteur : la lutte contre la paresse intellectuelle
A new mouse model of rheumatoid arthritis:organ-specific disease provoked by systemic autoimmunity
Ram pressure stripping in the zâââŒââ0.5 galaxy cluster MS 0451.6-0305
The pressure exerted by the ambient hot X-ray gas on cluster galaxies can lead to the presence of ram pressure stripped (RPS)
galaxies, characterized by asymmetric shapes, and, in some cases, tails of blue stars and/or X-ray gas, with increased star formation.\ud
Aims. With the aim of increasing the known sample of RPS galaxies at redshift z ⌠0.5, notably higher than most RPS samples
presently known, we extended our searches for such galaxies to the cluster MS 0451.6-0305.
Methods. Our study is based on Hubble Space Telescope (HST) imaging in the F814W band (corresponding to a restframe wavelength
of 529 nm), covering a region of about 6 Ă 6 Mpc2
, an eight magnitude ground-based catalogue with photometric redshifts, and a
spectroscopic redshift catalogue. We defined as cluster members a spectroscopic redshift sample of 359 galaxies within ±4Ïv of the
mean cluster velocity, and a photometric redshift sample covering the [0.48, 0.61] range. We searched for RPS galaxies in the HST
images and tested the error on their classification with a Zooniverse collaboration. We also computed the phase space diagram of RPS
candidates in the spectroscopic sample. Finally, we ran the LePhare stellar population synthesis code through the GAZPAR interface
to analyze and compare the properties of RPS and non-RPS galaxies.
Results. We find 56 and 273 RPS candidates in the spectroscopic and photometric redshift samples, respectively. They are distributed
throughout the cluster and tend to avoid high density regions. The phase space diagram gives the percentages of virialized, backsplash,
and infall galaxies. RPS galaxy candidates typically show rather high star formation rates, young ages, and relatively low masses. We
compare all our results to those previously obtained for the massive merging cluster MACS J0717+3745, at a similar redshift.
Conclusions. This study increases by at least 56 objects if we only consider galaxies with spectroscopic redshifts, and probably much
more if galaxies with photometric redshifts are taken into account. This study increases the number of RPS candidates at redshift
z > 0.5, and confirms that they host, on average, younger stellar populations and strongly form stars when compared with non-RPS
counterparts. The fact that RPS candidates with spectroscopic and with photometric redshifts have comparable properties shows that
large samples of such objects could be gathered based on multi-band photometry only, a promising result in view of the very large
imaging surveys planned in the coming years (DES, Euclid, LSST, etc.
Ram pressure stripping in the zâââŒââ0.5 galaxy cluster MS 0451.6-0305
The pressure exerted by the ambient hot X-ray gas on cluster galaxies can lead to the presence of ram pressure stripped (RPS) galaxies, characterized by asymmetric shapes, and, in some cases, tails of blue stars and/or X-ray gas, with increased star formation. Aims. With the aim of increasing the known sample of RPS galaxies at redshift z ⌠0.5, notably higher than most RPS samples presently known, we extended our searches for such galaxies to the cluster MS 0451.6-0305. Methods. Our study is based on Hubble Space Telescope (HST) imaging in the F814W band (corresponding to a restframe wavelength of 529 nm), covering a region of about 6 Ă 6 Mpc2 , an eight magnitude ground-based catalogue with photometric redshifts, and a spectroscopic redshift catalogue. We defined as cluster members a spectroscopic redshift sample of 359 galaxies within ±4Ïv of the mean cluster velocity, and a photometric redshift sample covering the [0.48, 0.61] range. We searched for RPS galaxies in the HST images and tested the error on their classification with a Zooniverse collaboration. We also computed the phase space diagram of RPS candidates in the spectroscopic sample. Finally, we ran the LePhare stellar population synthesis code through the GAZPAR interface to analyze and compare the properties of RPS and non-RPS galaxies. Results. We find 56 and 273 RPS candidates in the spectroscopic and photometric redshift samples, respectively. They are distributed throughout the cluster and tend to avoid high density regions. The phase space diagram gives the percentages of virialized, backsplash, and infall galaxies. RPS galaxy candidates typically show rather high star formation rates, young ages, and relatively low masses. We compare all our results to those previously obtained for the massive merging cluster MACS J0717+3745, at a similar redshift. Conclusions. This study increases by at least 56 objects if we only consider galaxies with spectroscopic redshifts, and probably much more if galaxies with photometric redshifts are taken into account. This study increases the number of RPS candidates at redshift z > 0.5, and confirms that they host, on average, younger stellar populations and strongly form stars when compared with non-RPS counterparts. The fact that RPS candidates with spectroscopic and with photometric redshifts have comparable properties shows that large samples of such objects could be gathered based on multi-band photometry only, a promising result in view of the very large imaging surveys planned in the coming years (DES, Euclid, LSST, etc.
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