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Background: Nebivolol is a β-adrenergic receptor antagonist that has intrinsic activity on β3-adrenergic receptors (β3-ARs). Previous studies suggest that nebivolol inhibits bFGF-induced vascular smooth muscle cell (VSMC) proliferation and migration and vascular injury-induced neointima formation through activation of β3-ARs. However, our recently published data shown that activation of β3-ARs produced the opposite results, suggesting that the mechanisms of nebivolol-mediated effects are not fully understood. The current project was to study the mechanisms of nebivolol’s effects on bFGF-induced VSMC proliferation and migration by comparing to the selective β3-AR agonist, CL316,243. Methods: VSMCs isolated from Sprague Dawley rat aortas were pretreated with nebivolol or CL316,243 followed by stimulation with bFGF. Cell proliferation and migration and phosphorylation of ERK and AKT were measured. Results: We found that pretreatment of VSMCs with nebivolol produced biphasic effects on bFGF-induced VSMC proliferation, manifested as potentiation at lower concentrations and inhibition at the higher concentration. The effects of low concentrations of nebivolol on bFGF-induced VSMC proliferation was blocked by the selective β3-AR antagonist, SR59230A. Nebivolol inhibited bFGF-induced cell migration at all concentrations tested. In addition, only higher concentrations of nebivolol significantly inhibited bFGF-induced AKT phosphorylation but not ERK phosphorylation whereas CL316,243 at all concentrations tested significantly enhanced bFGF-induced VSMC proliferation and migration and higher concentrations of CL316,243 not only enhanced bFGF-induced AKT phosphorylation but also ERK phosphorylation. Conclusion: Our data suggest that the effect of nebivolol on bFGF-induced cell proliferation is concentration-dependent. The enhancement on bFGF-induced cell proliferation at lower concentrations appears to be mainly mediated by activation of β3-ARs but the inhibitory effects on bFGF-mediated cell proliferation as well as migration may occur through different mechanisms. AKT signaling is only involved in high concentrations of nebivolol-mediated effects.

Structural assessment is critical for designing asphalt pavement overlays, estimating the remaining life of pavements, and selecting an appropriate rehabilitation strategy for existing pavements. The falling weight deflectometer (FWD) serves as the primary nondestructive test used for evaluating the in situ properties and structural capacity of asphalt pavements. The current procedure involves analyzing the FWD response and estimating layer moduli by assuming an elastic response. However, the response of asphalt layers is viscoelastic (i.e., temperature- and frequency-dependent). This study proposes an approach that combines FWD data with laboratory measurements of the dynamic moduli of field cores to determine the in situ viscoelastic properties of asphalt layers. This approach is implemented by analyzing FWD data from four pavement sections in Qatar. Furthermore, the paper includes a comparative analysis of the response of pavement sections in which the asphalt layers are modeled using dynamic modulus master curves obtained from laboratory tests and those obtained using the approach presented in this study. It was found that using the laboratory-based master curves overestimated pavement performance (i.e., underestimated pavement distresses). It is recommended to use the dynamic moduli from the method presented in this paper for a more accurate estimation of pavement response and performance.