Exosomes are small vesicles with a diameter of about 40-160 nm actively secreted by cells. They participate in a variety of pathophysiological processes and are closely related to the occurrence and development of diseases. As a newly carrier of intercellular communication and circulating biomarkers of disease diagnosis and prognosis, exosomes have attracted great attention for their potential clinical applications. However, many aspects such as exosome biogenesis, targeted transport, and mechanism of action are still unclear. This paper focuses on the exosome biogenesis, summarizes the exosome biogenesis pathways, and describes relevant molecular modulation mechanisms of importance. And this review provides a theoretical basis for disease treatment based on regulating exosome production.

BACKGROUND: Preliminary study has prepared the three-dimensional silk fibroin/chitosan/nano-hydroxyapatite scaffold successfully.OBJECTIVE: To explore the mechanical properties, physical characteristics, chemical composition and antibiotic sustained-release ability of three-dimensional silk fibroin/chitosan/nano-hydroxyapatite scaffold loaded with levofloxacin. METHODS: Levofloxacin/chitosan (3:1) microspheres were constructed by emulsion settlement filter method. 5, 7.5 and 10 g of microspheres were added into 2％ of silk fibroin/chitosan/nano-hydroxyapatite mixed solution through freeze drying and chemical cross-linking to obtain the scaffolds loaded with antibiotics. The scaffolds loaded with antibiotics underwent scanning electron microscope observation, and chemical composition analysis. The sustained release, mechanical properties, porosity, water absorption expansion rate and hot water soluble loss rate were detected. RESULTS AND CONCLUSION: (1) Scanning electron microscope observed that there were drug microspheres at the inner wall of the scaffold, and the voidage was decreased with mass of microspheres increasing. (2) Energy spectrum analysis showed that the three kinds of scaffolds were rich in calcium and phosphonium ions. (3) The three kinds of scaffolds showed the same releasing trend, which presented with sudden-release effect at the former 3 days (release> 50％) , and then tended to be stable. The release rate was the slowest in the scaffold loaded with 10 g of microscopes, and the rapidest in the scaffold loaded with 5 g of microscopes. (4) With the mass of microspheres increasing, there was an increase in the compressive and tension abilities and hot water soluble loss rate, and a decrease in the porosity, mean pore size and water absorption expansion rate. (5) These results indicate that the three-dimensional tissue-engineered scaffold loaded with levofloxacin is constructed successfully by freeze drying and chemical cross-linking method, which holds good sustained-release effect and compressive ability, water absorption expansion rate and hot water soluble loss rate.

Objective:To analyze the brain function of patients with delirium in intensive care unit (ICU) using resting-state functional magnetic resonance imaging (fMRI), further analyze the structural changes in the brain using diffusion tensor imaging (DTI), and explore the correlations of brain function with structural changes in patients with delirium in ICU from a new perspective of functional imaging, provide visual evidence for the diagnosis of delirium.Methods:Patients with delirium admitted to ICU of the Affiliated Hospital of Zunyi Medical University from January 1st to December 31st in 2017 were enrolled as subjects. During the same period, the healthy volunteers who matched the gender, age and education level of the patients with delirium were enrolled as control group. The intensive care delirium screening checklist (ICDSC) scores within 24 hours after ICU admission were recorded. All the subjects were scanned by fMRI and DTI. The abnormal changes in resting-state brain function of the patients with delirium were evaluated by cerebral regional homogeneity (ReHo) data analysis. The DTI data were processed by the FSL software, and the fractional anisotropy (FA) and mean diffusivity (MD) of the brain were extracted, respectively, to evaluate the damage to brain structure. The values of ReHo, FA and MD were compared between the two groups. The ReHo value of brain region with reduced ReHo value of patients with delirium as compared with the healthy volunteers was extracted for Pearson correlation analysis with ICDSC scores.Results:A total of 22 patients with delirium were included. Seven patients who did not cooperate in the examination, used sedatives or had false images in scanning, were excluded. Finally, 15 patients were enrolled in the delirium group, and 15 healthy volunteers in the healthy control group. ① No statistically significant difference was found in gender, age or education time between the two groups. ICDSC score of the delirium group was significantly higher than that of the healthy control group (6.07±1.28 vs. 1.07±0.88, P < 0.01). ② fMRI scanning and analysis results: compared with the healthy control group, the ReHo values of the cerebellum, right hippocampus, striatum, midbrain and pons in the delirium group were significantly increased (all P < 0.05, AlphaSim correction), while the ReHo values of bilateral superior frontal gyrus, bilateral median frontal gyrus, left inferior frontal gyrus, temporal lobe and parietal lobe were significantly lowered (all P < 0.05, AlphaSim correction). Correlation analysis showed that the ReHo value of the left superior frontal gyrus was negatively correlated with ICDSC score in the patients with delirium ( r = -0.794, P < 0.05), indicating that the changes in the functional area of the medial frontal gyrus was most closely related to delirium. ③ DTI scanning and analysis results: compared with the healthy control group, the FA values of the left cerebellum, bilateral frontal lobes, left temporal lobe, corpus callosum and left hippocampus in the delirium group were decreased significantly (all P < 0.05, AlphaSim correction), while the MD values of the medial frontal gyrus, right superior temporal gyrus, anterior cingulate gyrus, bilateral insular lobes and left caudate nucleus were enhanced significantly (all P < 0.05, AlphaSim correction), suggesting that the structural and functional damage was found in multiple brain regions in patients with delirium. Conclusions:Multiple brain regions of patients with delirium present abnormal resting-state brain function. The abnormal resting-state brain function of the left superior frontal gyrus is closely related to the occurrence of delirium. Structural damage is found in multiple brain regions of patients with delirium. The structural changes in the frontal lobe, temporal lobe, corpus callosum, hippocampus and cerebellum and their abnormal functions can be used as preliminary imaging indexes for the diagnosis of delirium.