Biomedical subjects

Lucia Riccardi

Publications and source records attributed to Lucia Riccardi.

3 recordsLinked to original sources

PubMed2003

An N-terminal 80 kDa recombinant fragment of human thrombospondin-2 inhibits vascular endothelial growth factor induced endothelial cell migration in vitro and tumor growth and angiogenesis in vivo.

We have previously shown that stable overexpression of the thrombospondin-2 (TSP-2) gene inhibited the tumor growth and angiogenesis of human squamous cell carcinoma xenotransplants. To investigate the potential antitumoral efficacy of systemic TSP-2 therapy, we expressed a recombinant 80 kDa fragment of human TSP-2 (TSP-2/NTF), encompassing the N-terminal globular region through the three type 1 repeats, in human kidney 293 EBNA cells, using a modified pCEP4 expression vector. Daily intraperitoneal injections of TSP-2/NTF resulted in a significant inhibition of the growth of human A431 squamous cell carcinomas in vivo and in reduced tumor vascularization. To further investigate possible mechanisms of the antiangiogenic activity of TSP-2/NTF, several in vitro angiogenesis assays were performed in human dermal microvascular endothelial cells. TSP-2/NTF inhibited vascular endothelial growth factor induced migration of human dermal microvascular endothelial cells and inhibited tube formation on Matrigel in vitro. TSP-2/NTF also inhibited vascular endothelial growth factor induced angiogenesis in an in vivo Matrigel assay. Moreover, TSP-2/NTF potently induced human dermal microvascular endothelial cell apoptosis in vitro but did not affect A431 tumor cell proliferation or apoptosis. These findings identify TSP-2/NTF as a potent systemic inhibitor of tumor growth and angiogenesis, acting by direct inhibition of several endothelial cell functions involved in neovascularization.

Animals↗

PubMed2002

Activation of the tie2 receptor by angiopoietin-1 enhances tumor vessel maturation and impairs squamous cell carcinoma growth.

The distinct roles of angiopoietin (Ang)-1 and Ang2, counteracting ligands for the endothelium-specific Tie2 receptor, in tumor development and progression have remained poorly understood. We investigated the expression of Ang1 and Ang2 during multistep mouse skin carcinogenesis and in human squamous cell carcinoma (SCC) xenografts. Expression of Ang2, but not of Ang1, was up-regulated in angiogenic tumor vessels already in early stages of skin carcinogenesis and was also strongly increased in SCCs. Stable overexpression of Ang1 in human A431 SCCs resulted in a more than 70% inhibition of tumor growth, associated with enhanced Tie2 phosphorylation levels, as compared with low levels in control transfected tumors. No major changes in the vascular density, vascular endothelial growth factor mRNA and protein expression, and vascular endothelial growth factor receptor-2 phosphorylation levels were observed in Ang1-expressing tumors. However, the fraction of tumor blood vessels with coverage by alpha-smooth muscle actin-positive periendothelial cells was significantly increased, indicative of an increased vascular maturation status. These findings identify an inhibitory role of Ang1/Tie2 receptor-mediated vessel maturation in SCC growth and suggest that up-regulation of its antagonist, Ang2, during early-stage epithelial tumorigenesis contributes to the angiogenic switch by counteracting specific vessel-stabilizing effects of Ang1.

Angiopoietin-1↗

PubMedDate not supplied

Acceptance testing of Computed Radiography systems.

Acceptance testing of computed radiography systems (CR) is required to verify not only image quality but also compliance with the manufacturer's specifications. Therefore, CR acceptance testing is manufacturer-specific. This paper describes a series of performance tests performed on a large number of CRs (FCR 5000, Fuji) recently acquired by our institution. In particular we describe the following tests: dark noise, uniformity, exposure calibration, linearity and autoranging, limiting resolution, noise and low-contrast resolution, spatial accuracy, laser-beam function, erasure thoroughness, aliasing, grid response. Special attention is given to the practical aspects related to measurement and subsequent image analysis. We report the results obtained in the various tests. No significant variations from the reference levels were found. Nonetheless, in some cases the operating procedures had to be adapted.

Artifacts↗