Targeted protein degradation via nanoparticle-based universal strategy modifies nanoparticles with antibodies and ingeniously utilizes its cellular transport characteristics. This strategy achieved targeted degradation of extracellular proteins without complex design.Image 1.

Objective:To discuss the suitable concentration of D-galactose(D-gal)and modeling period,and establish its induced aging-related cognitive dysfunction model in the mice,and perform a comprehensive evaluation.Methods:Fifty C57BL/6J mice were randomly divided into control group and 100,200,400,and 800 mg·kg-1 D-gal groups,with 10 mice in each group.The mice in various D-gal groups were subcutaneously injected with the corresponding concentration of D-gal once daily;the mice in control group were injected with an equal volume of normal saline.The body mass and water consumption of the mice in various groups were monitored;forelimb grip strength test and experiment on the ability of pole climbing sports were used to evaluate the motor coordination ability of the mice in various groups;novel object recognition test,Y maze test,and Morris water maze test were used to evaluate the cognitive function of the mice in various groups;HE staining and Nissl staining were used to observe the pathomorphology of brain tissue of the mice in various groups;immunohistochemistry method was used to detect the expression of β-galactosidase(β-gal)protein in brain tissue of the mice in various groups;real-time fluorescence quantitative PCR(RT-qPCR)method was used to detect the mRNA expression levels of interleukin(IL)-1β,tumor necrosis factor-α(TNF-α),IL-18,and IL-4 in hippocampus tissue of the mice in various groups;Western blotting method was used to detect the expression levels of β-gal,p53,and p16 proteins in hippocampus tissue of the mice in various groups.Results:The body mass growth trends of the mice in control group and various D-gal groups were consistent and there was no statistically significant difference(P>0.05),and there was no statistically significant difference in water consumption(P>0.05).After 8 weeks of subcutaneous injection of D-gal,compared with control group,the forelimb grip strength values of the mice in 200 and 400 mg·kg?1 D-gal groups were significantly decreased(P<0.05 or P<0.01);the pole-climbing time of the mice in 200 mg·kg?1 D-gal group was significantly prolonged(P<0.05);the recognition indexes of the mice in 200 and 400 mg·kg?1 D-gal groups were significantly decreased(P<0.01);the spontaneous alternation rate of the mice in 100,200,400,and 800 mg·kg?1 D-gal group was significantly decreased(P<0.05 or P<0.01),the escape latency was significantly increased(P<0.05).Spatial probe test showed that compared with control group,the escape latency of the mice in 200 mg·kg?1 D-gal group was significantly increased(P<0.05).The HE staining and Nissl staining results showed that compared with control group,the hippocampus neurons of the mice in 200 mg·kg-1 D-gal group were arranged disorderly,with obvious nuclear pyknosis,nuclear condensation,and abnormal morphology and structure,and the number of Nissl staining positive cells was significantly decreased.The immunohistochemistry results showed that compared with control group,the β-gal expressions in CA1 region,CA3 region,and cortex region of hippocampus tissue of the mice in 200 mg·kg?1 D-gal group were strongly positive.The RT-qPCR results showed that compared with control group,the expression levels of IL-1β,IL-18,and TNF-α mRNA in hippocampus tissue of the mice in 200 mg·kg?1 D-gal group were significantly increased(P<0.05 or P<0.01),and the expression level of IL-4 mRNA was significantly decreased(P<0.01).The Western blotting results showed that compared with control group,the expression levels of β-gal,p53,and p16 proteins in hippocampus tissue of the mice in 200 mg·kg?1 D-gal group were significantly increased(P<0.05 or P<0.01).Conclusion:The aging-related cognitive dysfunction model in the mice can be established by subcutaneous injection of 200 mg·kg?1 D-gal daily for 8 weeks.

Objective To study the effects of intramedullary pressure on the fluid flow behavior in bones.Methods Multi-scale models of macro bone tissue and macro-meso osteon groups were established using the COMSOL Multiphysics software.Considering the interrelationship of different pore scales,such as the bone marrow cavity,Haversia canal,and bone lacunar-canaliculus,the pore pressure and flow rate of hollow bone tissues and bone tissues with intramedullary pressure were compared,and the effects of the amplitude and frequency of intramedullary pressure on the pressure and flow velocity of the liquid in the bone were analyzed.Results When intramedullary pressure was considered,the pore pressure in bone tissues with intramedullary pressure was 6.4 kPa higher than that in hollow bone tissues.The flow pressure increased significantly with an increase in the intramedullary pressure amplitude,but the flow velocity remained unchanged.The frequency of intramedullary pressure had little effect on pore pressure and flow velocity.Conclusions The multi-scale pore model established in this study can accurately analyze bone fluid flow behavior.These results are of great significance for an in-depth understanding of force conduction in the bone.

Objective To investigate the conduction behavior of fluid flow induced by physiological loads at different scales of bone. Method sThe multiscale bone models were established by using the COMSOL Multiphysics software, and the fluid behaviors were investigated at macro-, meso- and micro-scale. Results At macro-meso scale，the distribution of pore pressure and fluid velocity of osteon near the periosteum and endoosteum were different from that in other parts. Due to the different structure and material parameters at different layers, the loading and fluid pressure caused different biomechanical responses in the process of transferring from macro-scale to micro-scale. Conclusions The multi-scale layered modeling of bone structure-osteon-lacunae-bone canaliculi was established, which provided the theoretical reference for deeper understanding of fluid stimulation and mechanotransduction.