Essai préliminaire de détection des champs d'ambroisie par télédétection spatiale

The detection of dense populations of ragweed (Ambrosia artemisiifolia L.) using spatial remote sensing methods seems possible. A sufficiently accurate map of parcels of land infested with ragweed could offer new possibilities to engage in weeding campaigns and to appreciate the space-time evolution of this plant. Obviously, the main difficulties in this approach are related to the heterogeneous floral composition of herbaceous stands and to the risk of confusion of the spectral composition of ragweed with that of other species. On 21 July 2001, we carried out field surveys in zones with abundant ragweed near Lyon (Department of the Rhone), and we used the resulting data in connection with two images of the same area obtained by the Terra ASTER 1B satellite on 26 June and 13 August 2001. A measurement was made in the laboratory on a sample of the plant obtained from the same area to determine its reflectance spectrum. On analysis of the spatial images, we were able to localize herbaceous patches in which ragweed is dominant. When the density of this plant decreases, the reflectance signals of the populations become multiform, requiring further studies. Further progress can be expected when sensors such as the spatial tel IKONOS (operating at a resolution in the order of 1 to 5 m) or the future SPOT 5 (operating at a resolution of 2 to 3 m in the panchromatic mode or at 10 m in a multispectral mode) will be used, allowing us to work at a resolution on the order of one meter.     

Hématomes intrahépatiques causés par HELLP syndrome

Spontaneous hematoma of the liver is a rare but extremely serious complication of HELLP syndrome (Hemolysis, elevated liver enzymes, and low platelets syndrome). The classical location is subcapsular, intra hepatic hematoma is exceptional. We report the case of a 33 years old multiparus woman, presenting with multiple and diffuse intra hepatic hematomas in postpartum, complicating a HELLP syndrome. We here by discuss, through a literature review, the epidemiology, localisation, diagnosis, treatment and prognosis of this affection.     

Urticaire idiopathique chronique par autoanticorps,intérêt et problématique du test cutané au sérum autologue

Chronic urticaria is said to be idiopathic when no etiology is uncovered. The autologous serum test has been found to be positive in 30–65% of such patients, which indicates the presence of an autoimmune mechanism. We present a case of chronic idiopathic urticaria with a positive autologous serum test, and we then discuss the rational for doing the test and its limits in clinical practice, as well as the underlying pathophysiological mechanisms associated with the presence of autoimmune antibodies, either anti-IgE autoantibodies or autoantibodies directed against the high affinity IgE receptor, FcεRI.