RESUMO
Because of helical phase wavefront distribution, vortex electromagnetic waves are considered to carry more information and additional degrees of freedom than traditional spherical waves. Therefore, a vortex wave carrying orbital angular momentum (OAM) can improve inversion and imaging accuracy. In this work, we revisit the reconstruction of three-dimensional objects in layered composite structures extended with OAM. In forward modeling, the concentric uniform circle array is used to generate electromagnetic vortex beams. To analyze the difference of vortex beams, the electric field radiation pattern and phase pattern distribution of OAM waves with different modes are calculated. Then, the scattered field of layered media illuminated by different OAM beams is determined by the dyadic Green's function and the stabilized biconjugate gradient technique with a fast Fourier transform algorithm. In the inversion, the variational Born iterative method is used to reconstruct targets in layered composite structures, and multiple OAM modes are used to improve the reconstruction results. The numerical results prove that the permittivity of the target can be better reconstructed by using the multiple OAM modes rather than the traditional spherical wave. With the increase of OAM mode number, the reconstructed target parameters are closer to the true value. We expect that our results will provide a better understanding of the OAM and pave the way for the improvement of inversion and optical imaging technology using vortex waves.
RESUMO
The tumor suppressor gene p53 is often inactivated in breast cancer cells due to gene mutation or overexpression of its repressors (such as murine double minute 2 and murine double minute X). Inhibitors of murine double minute 2 (MDM2) and murine double minute X (MDMX) could lead to tumor suppression by restoration of p53 activity and such an approach is a promising strategy for future control of breast cancer. This study aimed to investigate the feasibility of the recombinant MDM2 and MDMX inhibitory protein in control of breast cancer in vitro. A cell-permeable dual-target MDM2/MDMX inhibitory protein was expressed in E. coli and incubated with p53 wild-type breast cancer cells. The data showed that this recombinant MDM2/MDMX inhibitory protein reduced the viability of MCF-7 and ZR-75-30 breast cancer cell lines and promoted cell cycle arrest and apoptosis by activation and stabilization of the p53 protein. Mechanistically, this MDM2/MDMX inhibitory protein increased the expression of p21, Bax and puma proteins, and inhibitory expression of MDM2 and MDMX proteins. This recombinant protein showed a better in vitro effect than that of nutlin-3α, a small molecule MDM2 inhibitor. The data further support the hypothesis that targeting of the p53 gene pathway could effectively control breast cancer.
