Connexin36 (Cx36) plays an important role in insulin secretion by controlling the intercellular synchronization of Ca2+ transients induced during stimulation. The lack of drugs acting on Cx36 channels is a major limitation in further unraveling the molecular mechanism underlying this effect. To screen for such drugs, we have developed an assay allowing for a semi-automatic, fluorimetric quantification of Ca2+ transients in large populations of MIN6 cells. Here, we show that (1) compared to control cells, MIN6 cells with reduced Cx36 expression or function showed decreased synchrony of glucose-induced Ca2+ oscillations; (2) glibenclamide, a sulphonylurea which promotes Cx36 junctions and coupling, increased the number of synchronous MIN6 cells, whereas quinine, an antimalarial drug which inhibits Cx36-dependent coupling, decreased this proportion; (3) several drugs were identified that altered the intercellular Ca2+ synchronization, cell coupling and distribution of Cx36; (4) some of them also affected insulin content. The data indicate that the intercellular synchronization of Ca2+ oscillations provides a reliable and non-invasive measurement of Cx36-dependent coupling, which is useful to identify novel drugs affecting the function of β-cells, neurons, and neuron-related cells that express Cx36.

This project concerns the management of a multimedia database (text and image) of historical papers representing ancient watermarks. The current database contains roughly 3'000 images of such watermarks; the system allows archival and retrieval by means of textual or morphological criteria. During the archival phase, textual description are stored, as well as descriptive primitives extracted together with the watermark itself by image analysis methods. For the retrieval phase, several types of queries are supported; they allow textual search on the basis of the accompanying descriptions, morphological search according to global characteristics, and shape-based search on the basis of the watermark shape. 0-7803-3258-X/96/$5.00 0 1996 IEEE

We describe a new projectively invariant representation of disjoint contour groups which is suitable for shape-based retrieval from an image database. It consists of simultaneous polar reparametrization of multiple curves where an invariant point is used as the origin. For each ray orientation, a cross-ratio of its intersections with other curves is taken as a value associated to the radius. With respect to other methods this representation is less reliant on single curve properties, both for the construction of the projective basis and for calculating the signature. It is therefore more robust to contour gaps and image noise and is better suited to describing complex planar shapes defined by multiple disjoint curves. The proposed representation has been originally developed for planar shapes, but an extension is proposed and validated for 3D faceted objects. Moreover, we show that illumination invariance fits well within the proposed framework and can easily be introduced in the representation in order to make it more appropriate for shape-based retrieval. Experiments are reported on a database of real trademarks

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