Panax Notoginseng Saponins Regulate Angiogenic Cytokines Through the PI3K/AKT/mTOR Signaling Pathway to Promote Fracture Healing in Ovariectomized Rats.

Osteoporotic fractures seriously affect the quality of life of the elderly. Panax notoginseng saponins (PNS) have the potential function of preventing osteoporosis. The Phosphatidylinositol 3-kinase (PI3K)/protein kinase (AKT)/mammalian target of rapamycin (mTOR) pathway is involved in the regulation of osteoporosis and has been proven to be related to VEGF secretion and angiogenesis. Therefore, this study aimed to explore the effects of PNS on ovariectomized rats with osteoporotic fracture through the PI3K/AKT/mTOR pathway and angiogenesis-related factors. Female Sprague-Dawley rats were randomly divided into normal control, fracture model, ovariectomized fracture model, low-dose PNS (100 mg/kg/d), and high-dose PNS (200 mg/kg/d). The ovariectomized rat fracture model was established. In low and high dose groups, PNS was administered intraperitoneally. The vascularization of fracture ends was detected in vitro by micro-CT on the 7th, 14th, and 21st day after modeling, and the area and number of blood vessels in the unit field of vision of the callus healing plane were seen by hematoxylin-eosin staining. The expression levels of PI3K, AKT1, mTOR, hypoxia inducible factor-1; VEGF: vascular endothelial growth factor (HIF-1), VEGF, Ang-1, VEGFR2, and angiopoietin like 2 Gene (ANGPTL2) were determined using Western blotting. In the PNS treatment group, the area of cortical bone increased, the area of callus decreased, and the number and area of blood vessels increased significantly when compared with the ovariectomized fracture model group. PNS regulates the PI3K/AKT/mTOR signaling pathway and promotes the expression of vascular-related cytokines (VEGF, Ang-1, VEGFR2, and ANGPTL2) in osteoporotic fractures. PNS may regulate the expression of vascular-related factors through the PI3K/AKT/mTOR pathway and promote the healing of osteoporotic fractures in ovariectomized rats.

Lattice Boltzmann model for predicting frosting process on surfaces considering wettability.

The process of frosting is a multiscale problem, which leads to challenges of proposing accurate numerical methods. In this study, a lattice Boltzmann model for predicting frost formation and growth on surfaces of various wettabilities is proposed based on the heterogeneous nucleation and dendrite growth theories. Three lattice Boltzmann equations are used to calculate the velocity, humidity, and temperature distributions. Furthermore, the heterogeneous nucleation theory and dendrite growth theory are used to construct the equations that govern ice production during the frosting process, so that the surface wettability can be considered. After experimental validation, the model was used in the analysis of frosting behaviors on plates and in microchannels with different wettabilities. The effects of the intrinsic contact angles and roughness on the frost layer properties were evaluated. This study will likely facilitate a better understanding of frosting on the mesoscopic level.