Anti-Staphylococcus aureus effects of natural antimicrobial peptides and the underlying mechanisms.

Staphylococcus aureus can cause localized infections such as abscesses and pneumonia, as well as systemic infections such as bacteremia and sepsis. Especially, methicillin-resistant S. aureus often presents multidrug resistance, which becomes a major clinical challenge. One of the most common reasons for methicillin-resistant S. aureus antibiotic resistance is the presence of biofilms. Natural antimicrobial peptides derived from different species have shown effectiveness in combating S. aureus biofilms. In this review, we summarize the inhibitory activity of antimicrobial peptides against S. aureus planktonic cells and biofilms. We also summarize the possible inhibitory mechanisms, involving cell adhesion inhibition, membrane fracture, biofilm disruption and DNA disruption. We believe this can provide the basis for further research against S. aureus biofilm-associated infections.

When a bacterial infection is treated, sometimes not all bacteria are killed. This is because they have ways to evade the treatment's action. Therefore, it is important to develop new drugs, although this is difficult, expensive and time-consuming. This paper summarizes new types of natural antimicrobials that could be used against bacteria, how they work and how well.

Nonlinear effect of air pollution on adult pneumonia hospital visits in the coastal city of Qingdao, China: A time-series analysis.

Many studies have illustrated adverse effects of short-term exposure to air pollution on human health, which usually assumes a linear exposure-response (E-R) function in the delineation of health effects due to air pollution. However, nonlinearity may exist in the association between air pollutant concentrations and health outcomes such as adult pneumonia hospital visits, and there is a research gap in understanding the nonlinearity. Here, we utilized both the distributed lag model (DLM) and nonlinear model (DLNM) to compare the linear and nonlinear impacts of air pollution on adult pneumonia hospital visits in the coastal city of Qingdao, China. While both models show adverse effects of air pollutants on adult pneumonia hospital visits, the DLNM shows an attenuation of E-R curves at high concentrations. Moreover, the DLNM may reveal delayed health effects that may be missed in the DLM, e.g., ozone exposure and pneumonia hospital visits. With the stratified analysis of air pollutants on adult pneumonia hospital visits, both models consistently reveal that the influence of air pollutants is higher during the cold season than during the warm season. Nevertheless, they may behave differently in terms of other subgroups, such as age, gender and visit types. For instance, while no significant impact due to PM2.5 in any of the subgroups abovementioned emerges based on DLM, the results from DLNM indicate statistically significant impacts for the subgroups of elderly, female and emergency department (ED) visits. With respect to adjustment by two-pollutants, PM10 effect estimates for pneumonia hospital visits were the most robust in both DLM and DLNM, followed by NO2 and SO2 based on the DLNM. Considering the estimated health effects of air pollution relying on the assumed E-R functions, our results demonstrate that the traditional linear association assumptions may overlook some potential health risks.

Inhibition of Cancer Angiogenesis Using Triptolide Nanoparticles.

Tumor-associated angiogenesis is triggered by multiple angiogenic factors. Vascular endothelial growth factor blockers are currently a major mechanism of angiogenesis inhibition; however, either insensitivity due to the targeting of single angiogenic factors or serious side effects due to non-specific exposure ultimately leads to the failure of treatment. The herb-derived compound triptolide (TP) can inhibit tumor growth through multiple mechanisms. However, its hydrophobicity and side effects have hindered its translation to the clinic. Here, we have prepared TP-polymeric micelles (TP-PMs) using methoxy poly(ethylene glycol)-block-poly(ε-caprolactone). The drug loading efficiency and encapsulation efficiency can reach 7.2 ± 0.10% and 99.1 ± 1.05%, respectively. The TP-PM solution consisted of monodispersed particles (PDI = 0.100 ± 0.023), which were 53.1 ± 1.2 nm in size. In vitro release profiles indicated that the TP-PM solution exhibited better sustained-release action when compared with free TP solution. Pharmacokinetic and tumor tissue distribution studies showed that TP-PMs facilitated TP accumulation in tumor tissues. The tumor inhibition rate upon treatment with TP-PMs was higher than 50%, and the survival time of B16-F10 melanoma bearing mice was efficiently prolonged after TP-PM administration. In addition, serum VEGF levels and tumor incidence of the TP-PM-treated group were both significantly reduced, and histological analyses revealed that the tumor vessel diameter and density in the TP-PM-treated group were much smaller than those observed in the control groups. These results indicated that TP-PMs serve as a potential angiogenesis inhibitor.