Effect of tamoxifen in an experimental model of breast tumor studied by dynamic contrast-enhanced magnetic resonance imaging and different contrast agents.

OBJECTIVES: The aim of this study was to compare the efficacy of gadoteridol, B22956/1 (a new protein binding blood pool contrast agent), and (Gd-DTPA)37-albumin in detecting, by dynamic contrast-enhanced magnetic resonance imaging (MRI), the effect in vivo of tamoxifen in an experimental model of breast tumor implanted in rats. MATERIALS AND METHODS: Tumors were induced by subcutaneous injection of 10 mammary adenocarcinoma cells (13762 MAT B III). Treatment with tamoxifen (or vehicle) started on day 4 after implantation. On day 10 after implantation, animals were observed by MRI using B22956/1 (or gadoteridol) and, 24 hours later, using (Gd-DTPA)37-albumin. RESULTS: Dynamic contrast-enhanced magnetic resonance imaging data showed that tamoxifen treatment decreased vascular permeability to B22956/1, whereas no difference was detectable in permeability to gadoteridol or to (Gd-DTPA)37-albumin. No effect on fractional plasma volume was detected with either of contrast agents. CONCLUSIONS: B22956/1 is superior to both small Gd chelates and macromolecular contrast agents in the assessment of the effect of tamoxifen treatment on tumor vasculature.

Cytoskeleton reorganization and ultrastructural damage induced by gliadin in a three-dimensional in vitro model.

AIM: To evaluate the interplay between gliadin and LoVo cells and the direct effect of gliadin on cytoskeletal patterns. METHODS: We treated LoVo multicellular spheroids with digested bread wheat gliadin in order to investigate their morphology and ultrastructure (by means of light microscopy and scanning electron microscopy), and the effect of gliadin on actin (phalloidin fluorescence) and the tight-junction protein occludin and zonula occluden-1. RESULTS: The treated spheroids had deep holes and surface blebs, whereas the controls were smoothly surfaced ovoids. The incubation of LoVo spheroids with gliadin decreased the number of intracellular actin filaments, impaired and disassembled the integrity of the tight-junction system. CONCLUSION: Our data obtained from an "in vivo-like" polarized culture system confirm the direct noxious effect of gliadin on the cytoskeleton and tight junctions of epithelial cells. Unlike two-dimensional cell culture systems, the use of multicellular spheroids seems to provide a suitable model for studying cell-cell interactions.

Damaging effects of gliadin on three-dimensional cell culture model.

AIM: To evaluate the effects of gliadin on the oxidative environment in the "in vivo-like" model of a three-dimensional cell culture system. METHODS: LoVo cell line (intestinal adenocarcinoma) multicellular spheroids were treated with digested gliadin (with albumin used as a control). Spheroid volumes, cell viability and morphology, lactate dehydrogenase (LDH) release, content of reduced glutathione (GSH) and activity of GSH-related enzymes were examined. The data were statistically analyzed using the Student's t-test. was considered statistically significant. RESULTS: Gliadin reduced cell viability (from 20% to 60%) and led to morphological alterations characterized by apoptotic findings and cytoskeletal injuries. LDH activity increased. The content of GSH reduced (-20% vs controls), and activity of GSH-related enzymes was significantly inhibited. CONCLUSION: Gliadin treatment induces an imbalance in the antioxidative mechanism of cells cultured by the three-dimensional technique. This alteration may explain the cell damage directly caused by gliadin and the subsequent morphological abnormalities.

Contrast-enhanced MRI of murine sponge model for progressive angiogenesis assessed with gadoteridol (ProHance) and gadocoletic acid trisodium salt (B22956/1).

PURPOSE: To investigate the potential value of MRI for noninvasive assessment of angiogenesis in a murine model exploiting the properties of two contrast agents, gadoteridol (ProHance) and gadocoletic acid trisodium salt (B22956/1). MATERIALS AND METHODS: Biocompatible sponges were implanted in both mice flanks. Stimulated sponges contained human recombinant basic fibroblast growth factor (bFGF) as the angiogenic agent; control sponges contained vehicle. Angiogenesis was evaluated by MRI after injection of extravascular (ProHance) or blood-pool (B22956/1) contrast agents at different times after sponge implantation. Sponges signal intensity enhancement was calculated both as the relative enhancement and the rate of relative enhancement. Results from MRI were validated by classic biochemical (hemoglobin level and protein content) and morphological (histology) assays. RESULTS: The intrinsic different properties of ProHance and B22956/1 in wash-in and wash-out kinetics were useful to detect progressive vascularization and the establishment of a functional vascular network in the implants. Moreover, MRI allowed the appreciation of differences in neovessel colonization between bFGF-treated sponges and controls. Hemoglobin level, protein content, and histology confirmed the sponge vascularization and MRI results. CONCLUSION: Contrast-enhanced MRI is a reliable tool to study vascular characteristics in animal models of angiogenesis. The different kinetic properties of contrast agents can provide evidence of different functional neovascularization aspects and levels.