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Geoarcheologia dell’Isola di Pianosa
No full textIn questo lavoro sono trattati gli aspetti geoarcheologici del sito neolitico di Cala Giovanna Piano, in relazione alla frequentazione umana ed ai mutamenti ambientali, in particolare alle variazioni del livello marino
Preistoria e Protostoria dell’area tirrenica. Interreg IIIA Francia-Italia- “Isole” Toscana, Corsica, Sardegna
No full text
Nouvelles données sur le Néolithique ancien de l'aire corso-toscane
No full textThe authors summarise our knowledge of the Early Neolithic of the Corsican and Tuscan area, with special reference to Northern Corsica and Tuscany, and present new archaeological remains of this age recently found in the area. The Cala Giovanna Piano site (Pianosa Island, Arcipelago Toscano), excavated by a group of researchers from Corsica and Tuscany, has provided new data on the recent phase of the Early Neolithic. Studies carried out on other sites in Corsica and Tuscany give new insight into the Néolithisation process in this area of the Tyrrhenian region, the Arcipelago Toscano, which is the easiest way from Continental Tuscany to Corsica. The precise dating of the Early Neolithic in this area is still subject to debate.Les auteurs, après avoir rappelé le bilan des connaissances concernant le Néolithique ancien de l'aire corso-toscane (en fait, nord de la Corse et Toscane), présentent les nouvelles données archéologiques de cette phase apparues dans la zone considérée. Ainsi, le site de Cala Giovanna Piano (île de Pianosa, archipel toscan), fouillé par une équipe corso-toscane, a fourni des renseignements originaux relatifs à une phase récente du stade d'évolution analysé. D'autres sites toscans et corses, d'autres thèmes étudiés donnent l'occasion de porter un regard nouveau sur la néolithisation de cette région tyrrhénienne caractérisée, entre autres, par la voie de passage naturelle essentielle entre Toscane péninsulaire et Corse que constitue l'archipel toscan. Parmi les questions en suspens se dégage celle de la datation précise de la phase ancienne du premier Néolithique du secteur géographique examiné.Tozzi Carlo, Weiss Michel-Claude. Nouvelles données sur le Néolithique ancien de l'aire corso-toscane. In: Bulletin de la Société préhistorique française, tome 98, n°3, 2001. pp. 445-458
Identification of a bipotential precursor cell in hepatic cell lines derived from transgenic mice expressing cyto-Met in the liver.
No full textMet murine hepatocyte (MMH) lines were established from livers of transgenic mice expressing constitutively active human Met. These lines harbor two cell types: epithelial cells resembling the parental populations and flattened cells with multiple projections and a dispersed growth habit that are designated palmate. Epithelial cells express the liver-enriched transcription factors HNF4 and HNF1alpha, and proteins associated with epithelial cell differentiation. Treatments that modulate their differentiation state, including acidic FGF, induce hepatic functions. Palmate cells show none of these properties. However, they can differentiate along the hepatic cell lineage, giving rise to: (a) epithelial cells that express hepatic transcription factors and are competent to express hepatic functions; (b) bile duct-like structures in three-dimensional Matrigel cultures. Derivation of epithelial from palmate cells is confirmed by characterization of the progeny of individually fished cells. Furthermore, karyotype analysis confirms the direction of the phenotypic transition: palmate cells are diploid and the epithelial cells are hypotetraploid. The clonal isolation of the palmate cell, an immortalized nontransformed bipotential cell that does not yet express the liver-enriched transcription factors and is a precursor of the epithelial-hepatocyte in MMH lines, provides a new tool for the study of mechanisms controlling liver development
Inhibition of MMH (Met Murine Hepatocyte) cell differentiation by TGFbeta is abrogated by pre-treatment with the heritable differentiation effector FGF1
No full textMMH (Met murine hepatocyte) liver cells derived from transgenic mice expressing a truncated constitutively active form of human c-Met are non-transformed immortalized cell lines. We have previously shown that they harbor: (1) epithelial cells that express the liver-enriched transcription factors HNF4 and HNF1 alpha, and that can be stably induced by FGF1 to express liver functions, and (2) fibroblast-like bi-potential palmate cells that can differentiate into bile duct-like structures in Matrigel cultures, or into epithelial cells competent to express hepatic functions. Low concentrations of TGF beta have been found to inhibit growth and differentiation of MMH cells. The factor stabilized the palmate cell phenotype, and it provoked epithelial cells to acquire palmate-like morphological characteristics, in parallel with down-regulation of expression of HNF4 and HNF1 alpha and activation of Snail transcripts. The effects of TGF beta were dominant if it was added with FGF1, but the effects on differentiation were abrogated if cells had been pre-treated with FGF1, This work identifies TGF beta as a factor that could be implicated in maintaining bi-potential precursor cells in the liver, FGF1 as one that could override the TGF beta effects and Snail as a candidate for mediation of the signal
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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