Breast Elastography

Breast elastography has become a key complementary technique. A modality in the framework of breast pathology, complementary of B-mode imaging and colour doppler analysis. Breast ultrasound has provided morphological grayscale images and functional flow analysis of the soft breast tissues. Elastography now brings new physio-pathological information through the assessment of tissue elasticity. There are two different modalities: Real Time Elastography (RTE) and Shear Waves (SWE) ultrafast Imaging. Both techniques require a minimum adhesion to the skill rules for acquisition and interpretation so as to limit the operator dependant dimension and diagnostic errors. Elastography thus becomes perfectly reproducible with good accuracy in the different scores of the RTE or SWE classification. The aim of elastography in cancer screening is to achieve reliable lesion characterisation and better therapy monitoring/management

Breast ductal computer phantoms

International audienceMost of breast cancers (85%) originate from the epithelium and develop first in the ductolobular structures. Therefore, the mammary epithelium should be investigated in priority by means of an anatomically guided examination. For this purpose (mass screening, surgery navigation), we develop a two-dimensional anatomic phantom which corresponds to an axial cut of the ductolobular structures and enables one to better understand the interaction of the breast composition with ultrasound. The different constitutive tissues are modeled as a random inhomogeneous continuum with density and sound speed fluctuations. Ultrasonic pulse propagation through the breast computer phantom has been simulated using a finite element time domain method (the phantom can be used with others propagation codes). The simulated Ductal Echographic image is compared with the Ductal Tomographic (DT) reconstruction. The preliminary results reveal a higher quality of DT both in terms of contrast and resolution

Sciences, sociétés, pouvoirs : approches historiques

Dominique Pestre, directeur d’études avec Amy Dahan, directrice de recherche au CNRS Enseignement suspendu durant l’année universitaire 2003-2004. Dominique Pestre, directeur d’études Étude des sciences, histoire des sciences : lectures et études critiques Enseignement suspendu durant l’année universitaire 2003-2004

Estimation of potential evapotranspiration from extraterrestrial radiation, air temperature and humidity to assess future climate change effects on the vegetation of the Northern Great Plains, USA

The potential evapotranspiration (PET) that would occur with unlimited plant access to water is a central driver of simulated plant growth in many ecological models. PET is influenced by solar and long wave radiation, temperature, wind speed, and humidity, but it is often modeled as a function of temperature alone. This approach can cause biases in projections of future climate impacts in part because it confounds the effects of warming due to increased greenhouse gases with that which would be caused by increased radiation from the sun. We developed an algorithm for linking PET to extraterrestrial solar radiation (incoming top-of atmosphere solar radiation), as well as temperature and atmospheric water vapor pressure, and incorporated this algorithm into the dynamic global vegetation model MC1. We tested the new algorithm for the Northern Great Plains, USA, whose remaining grasslands are threatened by continuing woody encroachment. Both the new and the standard temperature-dependent MC1 algorithm adequately simulated current PET, as compared to the more rigorous PenPan model of Rotstayn et al. (2006). However, compared to the standard algorithm, the new algorithm projected a much more gradual increase in PET over the 21st century for three contrasting future climates. This difference led to lower simulated drought effects and hence greater woody encroachment with the new algorithm, illustrating the importance of more rigorous calculations of PET in ecological models dealing with climate change

Estimation of potential evapotranspiration from extraterrestrial radiation, air temperature and humidity to assess future climate change effects on the vegetation of the Northern Great Plains, USA

The potential evapotranspiration (PET) that would occur with unlimited plant access to water is a central driver of simulated plant growth in many ecological models. PET is influenced by solar and long wave radiation, temperature, wind speed, and humidity, but it is often modeled as a function of temperature alone. This approach can cause biases in projections of future climate impacts in part because it confounds the effects of warming due to increased greenhouse gases with that which would be caused by increased radiation from the sun. We developed an algorithm for linking PET to extraterrestrial solar radiation (incoming top-of atmosphere solar radiation), as well as temperature and atmospheric water vapor pressure, and incorporated this algorithm into the dynamic global vegetation model MC1. We tested the new algorithm for the Northern Great Plains, USA, whose remaining grasslands are threatened by continuing woody encroachment. Both the new and the standard temperature-dependent MC1 algorithm adequately simulated current PET, as compared to the more rigorous PenPan model of Rotstayn et al. (2006). However, compared to the standard algorithm, the new algorithm projected a much more gradual increase in PET over the 21st century for three contrasting future climates. This difference led to lower simulated drought effects and hence greater woody encroachment with the new algorithm, illustrating the importance of more rigorous calculations of PET in ecological models dealing with climate change

Le gouvernement et l’administration des techno-sciences à l’échelle globale aujourd’hui (Gatseg)

Dominique Pestre, Jean-Paul Gaudillière, directeurs d’étudesAmy Dahan, directrice de recherche au CNRS Le séminaire portant sur le gouvernement des et par les techno-sciences à l’échelle globale a connu deux moments différents. Dans le premier semestre, nous avons travaillé de façon chronologique, définissant pour chaque période (depuis la Seconde Guerre mondiale) les types d’experts impliqués dans ce gouvernement, les acteurs qui pèsent sur la définition des questions (entreprises, États, ON..

Perturbed hematopoiesis in mice lacking ATMIN

The ATM-interacting protein ATMIN mediates non-canonical ATM signaling in response to oxidative and replicative stress conditions. Like ATM, ATMIN can function as a tumor suppressor in the hematopoietic system: deletion of Atmin under the control of CD19-Cre results in B cell lymphomas in aging mice. ATM signaling is essential for lymphopoiesis and hematopoietic stem cell (HSC) function; however, little is known about the role of ATMIN in hematopoiesis. We thus sought to investigate if the absence of ATMIN would affect primitive hematopoietic cells in an ATM-dependent or -independent manner. Apart from its role in B cell development, we show that ATMIN has an ATM-independent function in the common myeloid progenitors (CMPs) by deletion of Atmin in the entire hematopoietic system using Vav-Cre. Despite the lack of lymphoma formation, ATMIN-deficient mice developed chronic leukopenia as a result of high levels of apoptosis in B cells and CMPs and induced a compensatory mechanism in which HSCs displayed enhanced cycling. Consequently, ATMIN-deficient HSCs showed impaired regeneration ability, with the induction of the DNA oxidative stress response, especially when aged. ATMIN therefore has multiple roles in different cell types and its absence results in perturbed hematopoiesis, especially during stress conditions and aging

Alterations in cellular metabolism modulate CD1d-mediated NKT-cell responses

Natural killer T (NKT) cells play a critical role in the host's innate immune response. CD1d-mediated presentation of glycolipid antigens to NKT cells has been established; however, the mechanisms by which NKT cells recognize infected or cancerous cells remain unclear. 5′-AMP activated protein kinase (AMPK) is a master regulator of lipogenic pathways. We hypothesized that activation of AMPK during infection and malignancy could alter the repertoire of antigens presented by CD1d and serve as a danger signal to NKT cells. In this study, we examined the effect of alterations in metabolism on CD1d-mediated antigen presentation to NKT cells and found that an infection with lymphocytic choriomeningitis virus rapidly increased CD1d-mediated antigen presentation. Hypoxia inducible factors (HIF) enhance T-cell effector functions during infection, therefore antigen presenting cells pretreated with pharmacological agents that inhibit glycolysis, induce HIF and activate AMPK were assessed for their ability to induce NKT-cell responses. Pretreatment with 2-deoxyglucose, cobalt chloride, AICAR and metformin significantly enhanced CD1d-mediated NKT-cell activation. In addition, NKT cells preferentially respond to malignant B cells and B-cell lymphomas express HIF-1α. These data suggest that targeting cellular metabolism may serve as a novel means of inducing innate immune responses