RESUMEN
Source localization and functional brain network modeling are methods of identifying critical regions during cognitive tasks. The first activity estimates the relative differences of the signal amplitudes in regions of interest (ROI) and the second activity measures the statistical dependence among signal fluctuations. We hypothesized that the source amplitude-functional connectivity relationship decouples or reverses in persons having brain impairments. Five Broca's aphasics with five matched cognitively healthy controls underwent overt picture-naming magnetoencephalography scans. The gamma-band (30-45 Hz) phase-locking values were calculated as connections among the ROIs. We calculated the partial correlation coefficients between the amplitudes and network measures and detected four node types, including hothubs with high amplitude and high connectivity, coldhubs with high connectivity but lower amplitude, non-hub hotspots, and non-hub coldspots. The results indicate that the high-amplitude regions are not necessarily highly connected hubs. Furthermore, the Broca aphasics utilized different hothub sets for the naming task. Both groups had dark functional networks composed of coldhubs. Thus, source amplitude-functional connectivity relationships could help reveal functional reorganizations in patients. The amplitude-connectivity combination provides a new perspective for pathological studies of the brain's dark functional networks.
RESUMEN
PURPOSE: Angiogenesis, which plays an important role in tumor growth and metastasis, is regulated by a balance between angiogenic stimulators and inhibitors. Pigment epithelium-derived factor (PEDF), a secreted glycoprotein is an important inhibitor of angiogenesis. Although the precise mechanisms by which PEDF exerts its actions remain poorly understood, there is growing evidence supporting the role of PEDF as a candidate antitumor agent. In this study, we investigated the role of PEDF in breast cancer. METHODS: We investigated the correlation of PEDF protein levels with cancer progression and prognosis in patients with invasive ductal breast cancer (IDC). We used immunohistochemistry in a cohort of 119 breast cancer patients to examine the expression of PEDF protein with an anti-PEDF antibody and to measure the microvessel density (MVD) with an anti-CD34 antibody. RESULTS: PEDF was an endogenous inhibitor of angiogenesis in endothelial cells. Decreased intratumoral expression of PEDF was associated with a higher microvessel density (MVD), a more metastatic phenotype, and poorer clinical outcome. PEDF was positive in 43.7% patients. Patients with low PEDF expression had a significantly higher MVD count when compared with patients with high PEDF expression. In univariate and multivariate analysis, PEDF was an independent prognostic factor. CONCLUSION: The inverse correlation between PEDF expression and MVD in human breast cancer suggests that low PEDF expression is associated with angiogenesis in breast cancer. PEDF expression is therefore a potentially useful prognostic marker for breast cancer.
