Antibacterial Activity and Mechanism of Action of Osthole against Listeria monocytogenes.

The purpose of this study was to investigate the antibacterial activity and mechanism of action of osthole against Listeria monocytogenes. The antibacterial activity of osthole was evaluated by determining the minimum inhibitory concentration (MIC) and growth curve. Cell morphology, membrane permeability, membrane integrity, bacterial physiology, and metabolism were explored using different methods to elucidate the mechanism of action of osthole. It was shown that the MIC of osthole against L. monocytogenes was 62.5 µg/mL and it inhibited the growth of L. monocytogenes effectively in a concentration-dependent manner. Scanning electron microscopy (SEM) images demonstrated morphology changes of L. monocytogenes, including rough surface, cell shrinkage, and rupture. It was found that extracellular conductivity and macromolecule content were increased significantly in the presence of osthole, indicating the disruption of cell membrane integrity and permeability. Laser confocal microscopy results supported the conclusion that osthole caused severe damage to the cell membrane. It was also noticed that osthole depleted intracellular adenosine triphosphate (ATP), inhibited Na+-K+-ATPase and Ca2+-Mg2+-ATPase activity, and promoted the accumulation of intracellular reactive oxygen species (ROS), leading to cell death. This study suggests that osthole is a promising antibacterial agent candidate against L. monocytogenes, and it shows potential in the prevention and control of foodborne pathogens.

Joint User Association and Deployment Optimization for Energy-Efficient Heterogeneous UAV-Enabled MEC Networks.

Unmanned aerial vehicles (UAVs) providing additional on-demand communication and computing services have become a promising technology. However, the limited energy supply of UAVs, which constrains their service duration, has emerged as an obstacle in UAV-enabled networks. In this context, a novel task offloading framework is proposed in UAV-enabled mobile edge computing (MEC) networks. Specifically, heterogeneous UAVs with different communication and computing capabilities are considered and the energy consumption of UAVs is minimized via jointly optimizing user association and UAV deployment. The optimal transport theory is introduced to analyze the user association sub-problem, and the UAV deployment for each sub-region is determined by a dragonfly algorithm (DA). Simulation results show that the energy consumption performance is significantly improved by the proposed algorithm.

Effect of senescence marker protein 30 on the proliferation and apoptosis of human lens epithelial cells SRA01/04.

AIM: To study the effect of senescence marker protein 30 (SMP30) on the proliferation and apoptosis of human lens epithelial cell (HLEC) SRA01/04. METHODS: SMP30 overexpression (OE) and knock down (KD) type cell lines were cultivated by using two groups regucalcin (RGN; SMP30) lentiviral vectors (LV-RGN, LV-RGN-RNAi) and the respective negative control virus infect SRA01/04 cells. Western blot and real-time quantitative polymerase chain reaction (q-PCR) analysis were used to determine RGN overexpression and knock down efficiency. We use cell counting kit-8 (CCK8) assay to measure cell viability and 5-bromodeoxyuridine (BrdU) assay to test cell proliferation. Cell cycle was measured by PI FACS assay and cell apoptosis was tested by Annexin V-APC assay through flow cytometry. We use Western blot to measure the content of caspase-3 in SRA01/04. RESULTS: We used PCR and Western blot techniques to determine the successful transfection of SMP30 OE and KD SRA01/04 cell lines. By CCK8, Brdu and PI FACS cell cycle assay, it was found that the SMP30 OE group promoted cell proliferation (P<0.05) compared with the control group, and the KD group inhibited cell proliferation (P<0.05). The results of Annexin V-APC signal staining detection indicated that compared with respective control group, the cell apoptosis rate was higher in KD group (P<0.05) but lower in OE group (P<0.01). The expression of caspase-3 was down-regulated in OE group through Western blot assay and up-regulated in KD group compared with respective control group. CONCLUSION: Proliferation of SRA01/04 was promoted by SMP30 OE and apoptosis was suppressed. Increasing the expression of SMP30 may protect HLEC SRA01/04 against apoptosis in cataract.