Polystyrene nanoplastics with different functional groups and charges have different impacts on type 2 diabetes.

BACKGROUND: Increasing attention is being paid to the environmental and health impacts of nanoplastics (NPs) pollution. Exposure to nanoplastics (NPs) with different charges and functional groups may have different adverse effects after ingestion by organisms, yet the potential ramifications on mammalian blood glucose levels, and the risk of diabetes remain unexplored. RESULTS: Mice were exposed to PS-NPs/COOH/NH2 at a dose of 5 mg/kg/day for nine weeks, either alone or in a T2DM model. The findings demonstrated that exposure to PS-NPs modified by different functional groups caused a notable rise in fasting blood glucose (FBG) levels, glucose intolerance, and insulin resistance in a mouse model of T2DM. Exposure to PS-NPs-NH2 alone can also lead the above effects to a certain degree. PS-NPs exposure could induce glycogen accumulation and hepatocellular edema, as well as injury to the pancreas. Comparing the effect of different functional groups or charges on T2DM, the PS-NPs-NH2 group exhibited the most significant FBG elevation, glycogen accumulation, and insulin resistance. The phosphorylation of AKT and FoxO1 was found to be inhibited by PS-NPs exposure. Treatment with SC79, the selective AKT activator was shown to effectively rescue this process and attenuate T2DM like lesions. CONCLUSIONS: Exposure to PS-NPs with different functional groups (charges) induced T2DM-like lesions. Amino-modified PS-NPs cause more serious T2DM-like lesions than pristine PS-NPs or carboxyl functionalized PS-NPs. The underlying mechanisms involved the inhibition of P-AKT/P-FoxO1. This study highlights the potential risk of NPs pollution on T2DM, and provides a new perspective for evaluating the impact of plastics aging.

Lateral Vibration Control of Long-Span Small-Radius Curved Steel Box Girder Pedestrian Bridge with Distributed Multiple Tuned Mass Dampers.

Curved pedestrian bridges are important urban infrastructure with the desired adaptability to the landscape constraints and with aesthetic benefits. Pedestrian bridges feature thin cross-sections, which provide sufficient load capacities but lead to low natural frequencies that make the bridges susceptible to vibration under pedestrian excitation. This study investigates the lateral vibration of a curved bridge with a small radius down to 20 m, proposes an approach to mitigate the lateral vibration of bridges with large curvatures using distributed multiple tuned mass dampers (MTMD), and conducts in-situ bridge tests to evaluate the vibration mitigation performance. The lateral vibration was investigated through in-situ tests and finite element analysis as well as the code requirements. The key parameters of the distributed MTMD system were improved by strategically selecting the mass ratio, bandwidth, center frequency ratio, and damper number. The results showed that the curved bridge was subjected to significant lateral vibration due to the coupling of torque and moment, and the recommended design parameters for the studied bridge were derived, i.e., the total mass ratio is 0.02, bandwidth is 0.15, center frequency ratio is 1.0, and damper number is 3. The proposed approach effectively improves the deployment of MTMD for lateral vibration control of the curved bridge. The field tests showed that the vibration was reduced by up to 82% by using the proposed approach.

The effect and a mechanistic evaluation of polystyrene nanoplastics on a mouse model of type 2 diabetes.

Nanoplastics have become ubiquitous in the global environment and have attracted increasing attention. However, whether there is an influence between exposure to nanoplastics and diabetes is unclear. To determine the effects of exposure to Polystyrene nanoplastics (PS-NPs) and evaluate the underlying mechanisms, mice were orally exposed to PS-NPs at dosages of 1, 10, 30 mg/kg/day for 8 weeks, alone or combined with a high fat diet and streptozocin (STZ) injection. Our data showed that exposure to 30 mg/kg/day PS-NPs alone induced a significant increase in blood glucose, glucose intolerance and insulin resistance. Combined with a high fat diet and STZ injection, PS-NPs exposure markedly aggravated oxidative stress, glucose intolerance, insulin tolerance and insulin resistance, and induced lesions in the liver and pancreas. PS-NPs exposure could decrease the phosphorylation of AKT and GSK3ß, and treatment with SC79, a selective AKT activator, could increase the level of AKT and GSK3ß phosphorylation, effectively alleviating the increase in ROS levels in the liver or pancreas, and slightly attenuating the increase in fasting blood glucose levels and insulin resistance induced by PS-NPs exposure. This showed that exposure to PS-NPs aggravated type 2 diabetes and the underlying mechanism partly involved in the inhibition of AKT/GSK3ß phosphorylation.

Co-exposure to polystyrene microplastics and di-(2-ethylhexyl) phthalate aggravates allergic asthma through the TRPA1-p38 MAPK pathway.

Increasing attention has been paid to the potential impact of microplastics (MPs) pollution on human health. MPs and phthalates coexist in the environment, however, the effects of exposure to MPs alone or to a combination of di-(2-ethylhexyl) phthalate (DEHP) and MPs on allergic asthma are unclear. This study investigates the effects of exposure to polystyrene microplastics (PS-MPs) or co-exposure with DEHP, on allergic asthma, and the underlying molecular mechanisms. We established an allergic asthma model using ovalbumin, and mice were exposed to PS-MPs (5 mg/kg bw/day) alone, or combined with DEHP (0.5, 5 mg/kg bw/day), for 28 days. The results showed that in the presence of ovalbumin (OVA) sensitization, exposure to PS-MPs alone slightly affected airway inflammation, and airway hyperresponsiveness, while co-exposure to PS-MPs and DEHP caused more significant damage. Co-exposure also induced more oxidative stress and Th2 immune responses, and activation of the TRPA1 and p38 MAPK pathways. The aggravation of asthmatic symptoms induced by co-exposure to PS-MPs and DEHP were inhibited by blocking TRPA1 ion channel or p38 MAPK pathway. The results demonstrated that co-exposure to PS-MPs and DEHP exacerbates allergic asthma, by exacerbating oxidative stress and inflammatory responses, and activating the TRPA1-p38 MAPK pathway.

Comparing the effects of polystyrene microplastics exposure on reproduction and fertility in male and female mice.

Microplastics (MPs) may have an impact on the reproductive development of humans and mammals. However, any effects of MPs exposure on male and female reproductive systems and fertility are still ambiguous. In this study, male and female C57BL/6 mice were exposed to saline or 0.1 mg/d polystyrene microplastics (PS-MPs) for 30 days or 44 days to determine the effects of MPs on reproductive systems, following which some of the mice were caged for 10 days to mate to test fertility. Another group of mice were given fluorescent PS-MPs to determine the accumulation of MPs. The results show that PS-MPs exposure resulted in more significant accumulation and oxidative stress in the ovary than in the testis. In male mice, the number of viable epididymis sperm and spermatogenic cells in the testes after PS-MPs exposure was significantly reduced, and the rate of sperm deformity increased. In female mice, PS-MPs exposure induced a decrease in ovary size and number of follicles. After exposure to PS-MPs, the levels of Follicle stimulating hormone, Luteinizing hormone and testosterone were reduced, and the estradiol levels increased in the serum of male mice, while the changes in these hormone levels of female mice was the opposite. The mice exposed to PS-MPs had a reduced pregnancy rate and produced fewer embryos. These findings suggest that exposure to PS-MPs damaged the testes and ovaries, induced oxidative stress, altered the serum hormone levels, and induced changes in reproduction and fertility. Female mice appear to be more susceptible to MPs in reproduction and fertility than male mice.