Running GAGs: myxoid matrix in tumor pathology revisited: What’s in it for the pathologist?

Ever since Virchow introduced the entity myxoma, abundant myxoid extracellular matrix (ECM) has been recognized in various reactive and neoplastic lesions. Nowadays, the term “myxoid” is commonly used in daily pathological practice. But what do today’s pathologists mean by it, and what does the myxoid ECM tell the pathologist? What is known about the exact composition and function of the myxoid ECM 150 years after Virchow? Here, we give an overview of the composition and constituents of the myxoid ECM as known so far and demonstrate the heterogeneity of the myxoid ECM among different tumors. We discuss the possible role of the predominant constituents of the myxoid ECM and attempt to relate them to differences in clinical behavior. Finally, we will speculate on the potential relevance of this knowledge in daily pathological practice

Characterisation of the seismological pattern in a slowly deforming intraplate region: Central and western France

Tectonophysics, v. 409, n. 1-4, p. 175-192, 2005. http://dx.doi.org/10.1016/j.tecto.2005.08.021International audienc

Geoheritage and the conservation of natural geological sites of interest in Guadeloupe, French West Indies

International audienceIn 2002, the law for a Democracy of Proximity was voted by the French parliament. It stated that the State takes care of the conception, the animation and the evaluation of the Natural Heritage. This heritage shall include all ecological, fauna, flora, geological, mineralogical and paleontological items of interest. For the Geoheritage, that is to say the geological sites of natural or human-related interest, Guadeloupe (French West Indies) was chosen as a test territory. Indeed, its geology is very rich and very peculiar, with a lot of variation. It includes for example a carbonate plat-form, living and fossil coral reefs, mangroves, on-shore and submarine thermal springs, a great variety of volcanic deposits, tropical erosion features typical of limestone’s (karsts) and an active volcano. Since 2003, several sites in Guadeloupe have been referenced and described. In 2015, all these sites had been validated at the national level and entered into a national database (IGeotope). This inventory is meant to be permanent and a living collection. Since in 2018, the DFA chapter (Guadeloupe-Martinique) of the Caribbean Academy of Sciences is re-evaluating the previous outcrops descriptions for adding new information to the sites. In the meantime, the CAS also starts working on new descriptions with the particularity of adding human related sites (Mazabraud, 2019). This project should be ongoing for four to five years. When finalized, a territorial geo-heritage catalogue reveals itself a powerful tool for policy making and education (Martin, 2013). Despite the need to inventory the underground for resource purposes (water, mining) that has motivated geological research for centuries, such an inventory is meant to be used for protecting areas of natural interest, for teaching and for developing tourism (Renau and Peissier, 2018)

Is earthquake activity along the French Atlantic margin favoured by local rheological contrasts ?,

International audienceThe seismological study of recent seismic crises near Oleron Island confirms the coexistence of an extensional deformation and a transtensive regime in the Atlantic margin of France, which is different from the general western European stress field corresponding to a strike-slip regime. We argue that the switch of the principal stress axes σ1/σ2 in a NW-SE vertical plane is linked with the existence of crustal heterogeneities. Events of magnitude larger than 5 sometimes occur along the Atlantic margin of France, such as the 7 September 1972 (ML = 5.2) earthquake near Oleron island and the 30 September 2002 (ML = 5.7) Hennebont event in Brittany. To test the mechanism of local strain localization, we model the deformation of the hypocentral area of the Hennebont earthquake using a 3D thermo-mechanical finite element code. We conclude that the occurrence of moderate earthquakes located in limited parts of the Hercynian shear zones (as the often reactivated swarms near Oleron) could be due to local reactivation of pre-existing faults. These sporadic seismic ruptures are favoured by stress concentration due to rheological heterogeneities

Evidence for short scale stress field variations within intraplate central-western France

Geophysical Journal International, v. 160, n. 1, p. 161-178, 2005. http://dx.doi.org/10.1111/j.1365-246X.2004.02430.xInternational audienceRefinement of the seismicity distribution (4574 events) in western and central France, has been done by synthesis of seismological bulletins. Earthquakes have then been relocated by joint hypocentre and velocity structure inversion. The new hypocentre distribution indicates that the seismicity of those regions is much less diffuse than previously thought, mainly with regard to the depth distribution. The hypocentre improvement allows us to compute 44 new focal mechanisms and to revise bibliographic focal mechanism solutions. Then, the regional stress field was determined from 119 available focal mechanisms. It is characterized by a regionally significant strike-slip regime with NW-trending σ 1. However, the refinement in location and increasing available focal mechanism solutions allow us to show that this strike-slip regime is overprinted by local extensional perturbations in three distinct areas. In the Massif Central, the Sillon Houiller, a ancient vertical shear zone, appears to be acting as a passive boundary between a western unit and an eastern unit that is uplifted by the ascension of a hot mantle plume at the base of the lithosphere. Extension is unexpectedly observed in the southern Armorican Massif (SAM), as well as in northwestern Massif Central. One can observe a good relation between the observed perturbed zones and lateral variation of Pn anisotropy in the mantle. This correlation and the scale of these areas are arguments in favour of a lithospheric process as the origin for the stress characteristics. We believe these extensional perturbations could be related to the anticlockwise rotation of the Iberian microplate and/or incipient subduction in the Bay of Biscay

Aftershocks of the 2002, September 30th, Mw 4.3 earthquake in Southern Brittany, France, and their tectonic significance

International audienc

Rapport préliminaire sur l'intervention sismique suite au séisme de Hennebont du 20 septembre 2002 (campagne SISBREIZH 2002)

INSUE-CNRS, 15-03-2003, 4 p

Analysis of the Mw 4.3 Lorient earthquake sequence: a multidisciplinary approach to the geodynamics of the Armorican Massif, westernmost France

A Mw 4.3 earthquake occurred on 2002 September 30, in the Armorican Massif, NW France. Since it was one of the largest events ever recorded in this region, this was the opportunity to improve our seismotectonic knowledge of the Armorican Massif. We performed a post-seismic survey (SISBREIZH), which allowed us to locate accurately 62 aftershocks within 14 days. An analysis of the main shock using broadband records provided a normal fault mechanism with a dextral strike-slip component located at 12-km depth. The aftershock sequence exhibits: (1) a combination of almost pure right-lateral strike-slip and dominant normal faulting similar to the main shock; (2) magnitudes ranging from 0.4 to 1.9 and (3) depths ranging from 11.5 to 13.5 km, that is, close to the main shock hypocenter. The distribution of the aftershocks defines a rupture plane dipping 60° to the south with a fault length of ≈2 km consistent with the source parameters of the main shock. Beside the SISBREIZH survey, a morpho-structural analysis has been conducted: we found fault plane solutions with southward-dipping N120-150 normal fault planes. The stress tensor computed after the aftershock focal mechanisms is a strike-slip regime with a NE-SW extensional direction. The Lorient earthquake appears to reactivate Late Hercynian structures and the whole sequence is reflecting the regional-scale tectonic stress field expressed by a combination of strike-slip and normal faulting

Analysis of the Mw = 4.3 Lorient earthquake sequence : a multidisciplinary approach to the geodynamics of the Armorican Massif, Westernmost France

International audienceSince it was one of the largest events ever recorded in this region, this was the opportunity to improve our seismotectonic knowledge of the Armorican Massif. We performed a post-seismic survey (SISBREIZH), which allowed us to locate accurately 62 aftershocks within 14 days. An analysis of the main shock using broadband records provided a normal fault mechanism with a dextral strike-slip component located at 12-km depth. The aftershock sequence exhibits: (1) a combination of almost pure right-lateral strike-slip and dominant normal faulting similar to the main shock; (2) magnitudes ranging from 0.4 to 1.9 and (3) depths ranging from 11.5 to 13.5 km, that is, close to the main shock hypocenter. The distribution of the aftershocks defines a rupture plane dipping 60 • to the south with a fault length of ≈2 km consistent with the source parameters of the main shock. Beside the SISBREIZH survey, a morpho-structural analysis has been conducted: we found fault plane solutions with southward-dipping N120-150 normal fault planes. The stress tensor computed after the aftershock focal mechanisms is a strike-slip regime with a NE-SW extensional direction. The Lorient earthquake appears to reactivate Late Hercynian structures and the whole sequence is reflecting the regional-scale tectonic stress field expressed by a combination of strike-slip and normal faulting