[Research advances on the application of silk fibroin biomaterials in wound repair].

Silk fibroin, a natural fibrin, is a suitable matrix biomaterial for wound repair due to its unique properties such as good biocompatibility, tunable biodegradation and mechanical properties, low host inflammatory response, low cost, ease of fabrication, etc. Silk fibroin can be used alone or in combination with other materials to construct various dressings including scaffolds, hydrogels, films, smart mats, and microneedles, which can meet the needs of different wound repair and regulate the wound repair process. Thus, the application research of silk fibroin in skin tissue engineering has increased dramatically. Compared with other natural materials, silk fibroin promotes tissue regeneration and wound repair by improving cell proliferation, migration, and differentiation behavior at different stages, showing unique advantages in different dimensions. Based on the development of silk fibroin wound repair materials in the recent years, this review focuses on the mechanism and application prospect of silk fibroin and its composite materials in wound repair.

Risk Factors Associated with the Outcome of Post-Traumatic Hydrocephalus.

BACKGROUND AND AIM: Post-traumatic hydrocephalus is a common complication that arises after head injury. However, risk factors associated with the outcome of post-traumatic hydrocephalus have seldom been addressed. Therefore, we performed this clinical study to analyze the risk factors affecting the outcome of post-traumatic hydrocephalus in patients with head injuries. METHODS: A total of 116 post-traumatic hydrocephalus patients, admitted in our hospital between March 2012 and October 2017 were reviewed. The related factors assessed were age, gender, Glasgow Coma Score on admission, platelet count, plasma fibrinogen levels, D-dimer concentration, subarachnoid hemorrhage, subdural hygroma, cerebral hernia, cisterna ambiens, decompressive craniectomy, cranioplasty, ventriculoperitoneal shunt implantation, intracranial infection, and duration of comatous state. The patient outcomes after 6 months of treatment were evaluated by the Glasgow Outcome Scale. Risk factors for the outcome of post-traumatic hydrocephalus were evaluated by applying logistic regression analysis. RESULTS: Poor outcome was observed in 66.4% of the patients (77/116). Univariate and multivariate analyses revealed that the disappearance of cisterna ambiens, the long duration of comatous state (>2 months), the high levels of plasma fibrinogen, and the ventriculoperitoneal shunt implantation were related to adverse outcomes (p < 0.05). CONCLUSION: The disappearance of cisterna ambiens, the prolonged duration of comatous state (>2 months), the high plasma fibrinogen levels are the most important factors affecting the outcome of post-traumatic hydrocephalus, and the ventriculoperitoneal shunt implantation is the most critical predictor of the outcome of post-traumatic hydrocephalus.

Simulation of ECM with Silk and Chitosan Nanocomposite Materials.

Extracellular matrix (ECM) is a system used to model the design of biomaterial matrices for tissue regeneration. Various biomaterial systems have been developed to mimic the composition or microstructure of the ECM. However, emulating multiple facets of the ECM in these systems remains a challenge. Here, a new strategy is reported which addresses this need by using silk fibroin and chitosan (CS) nanocomposite materials. Silk fibroin was first assembled into ECM-mimetic nanofibers in water and then blended with CS to introduce the nanostructural cues. Then the ratios of silk fibroin and CS were optimized to imitate the protein and glycosaminoglycan compositions. These biomaterial scaffolds had suitable compositions, hierarchical nano-to-micro structures, and appropriate mechanical properties to promote cell proliferation in vitro, and vascularization and tissue regeneration in vivo. Compared to previous silk-based scaffolds, these scaffolds achieved improvements in biocompatibility, suggesting promising applications in the future in tissue regeneration.

Bioactive Natural Protein-Hydroxyapatite Nanocarriers for Optimizing Osteogenic Differentiation of Mesenchymal Stem Cells.

Improving the controlled release of bioactive growth factors to regulate cell behavior and tissue regeneration remains a need in tissue engineering and regenerative medicine. Inorganic and polymeric nanoparticles have been extensively fabricated as bioactive biomaterials with enhanced biocompatibility and effective carriers of therapeutic agents, however, challenges remain such as the achievement of high loading capacity and sustained release, and the bioactivity preservation of growth factors. Here, a multilayered, silk coated hydroxyapatite (HA) nanocarrier with drug loading-release capacity superior to pure silk or HA nanoparticles was developed. Bone morphogenetic protein-2 (BMP-2) was bound to the silk coatings with a high binding efficiency of 99.6%, significantly higher than that in silk or the HA nanoparticles alone. The release of BMP-2 was sustained in vitro over a period of 21 days without burst release. Compared with BMP-2 loaded silk or HA particles, bone mesenchymal stem cells (BMSCs) showed improved proliferation and osteogenesis when cultured with the BMP-2 loaded composite nanocarriers. Therefore, these silk-HA composite nanoparticles present a useful approach to designing bioactive nanocarrier systems with enhanced functions for bone tissue regeneration needs.

[Research on correlations between climatic factors and diosgenin content in Dioscorea zingiberensis Wright].

Dioscorea zingiberensis wright is native to China. In this paper correlations between seven climatic factors (mean annual temperature, mean annual relative humidity, mean annual 5 cm soil temperature, annual precipitation. Annual sunshine hours, mean annual sunshine percentage and annual greater than or equal to 10 degrees C accumulative temperature) and diosgenin content has been reported. It is annual precipitation and mean annual 5 cm soil temperature that are real principal factors affecting the diosgenin content. The most suitable climatic range for the biosynthesis and accumulation of diosgenin is as follows: Annual precipitation: 800-900 mm, 850 mm the best. Mean annual 5 cm soil temperature: 15-17 degrees C, 16 degrees C the best.