[The effects of anabolic-androgenic steroids on behavioral, cognitive functions and nervous systems of adolescents].

Anabolic-androgenic steroid (AAS) is responsible for muscle building and masculinizing. Using AAS can enhance muscle development and strength, and improve athletic performance. AAS abuse is not only seen in sport. Research has shown that there is an increasing number of adolescent AAS abusers. Adolescents are at a critical period of physical and mental development. Sex hormones are one of the important physiological factors affecting the development of their bodies and brains. Long-term or high-dose AAS treatment is likely to cause irreversible damage to their nervous system and psychological behavior, and these effects are easily overlooked. The article reviewed the long-term adverse effects of AAS on psychological behavior, emotion, cognitive functions and the nervous system of adolescents.

Enhancement of surface bioactivity on carbon fiber-reinforced polyether ether ketone via graphene modification.

BACKGROUND AND OBJECTIVE: The modulus of carbon fiber-reinforced polyether ether ketone (CFR-PEEK), a composite containing layers of carbon fiber sheets, can be precisely controlled to match bone. However, CFR-PEEK is biologically inert and cannot promote bone apposition. The objective of this study was to investigate whether graphene modification could enhance the bioactivity of CFR-PEEK. METHODS AND RESULTS: In vitro, the proliferation and differentiation of rat bone marrow stromal cells on scaffolds were quantified via cell-counting kit-8 assay and Western blotting analysis of osteoblast-specific proteins. Graphene modification significantly promoted bone marrow stromal cell proliferation and accelerated induced differentiation into osteogenic lineages compared to cells seeded onto nongraphene-coated CFR-PEEK. An in vivo rabbit extraarticular graft-to-bone healing model was established. At 4, 8, and 12 weeks after surgery, microcomputed tomography analyses and histological observations revealed significantly better microstructural parameters and higher average mineral apposition rates for graphene-modified CFR-PEEK implants than CFR-PEEK implants (P<0.05). van Gieson staining indicated more new bone was formed around graphene-modified CFR-PEEK implants than CFR-PEEK implants. CONCLUSION: Graphene may have considerable potential to enhance the bioactivity and osseointegration of CFR-PEEK implants for clinical applications.

Effects of graphene modification on the bioactivation of polyethylene-terephthalate-based artificial ligaments.

The objective of this study was to investigate whether surface coating with graphene could enhance the surface bioactivation of PET-based artificial ligaments to accelerate graft-to-bone healing after anterior cruciate ligament reconstruction. In an in vitro study, the proliferation of MC3T3-E1 cells and their differentiation on the scaffolds were quantified via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and real-time polymerase chain reaction assays. The significantly higher optical-density values and transcription levels of osteoblast-specific genes indicated that graphene modification could promote the proliferation of MC3T3-E1 cells and accelerate their specific differentiation into osteogenic lineages on scaffolds. In an in vivo test, rabbits were used to establish an extra-articular graft-to-bone healing model. At 4, 8, and 12 weeks after surgery, biomechanical tests, microcomputed tomography analysis, and histological observations were performed. The final results demonstrated that the microstructural parameters, the average mineral apposition rate of the bone, and the biomechanical properties of the graphene-coated polyethylene terephthalate (PET)-based artificial ligament (G-PET-AL) group were significantly higher than those of the PET-AL graft group (P < 0.05). The results of Van Gieson staining indicated that in the G-PET-AL group, there was more newly formed bone than there was in the group in which nongraphene-coated PET-ALs were used. In conclusion, graphene exhibits considerable potential for enhancing the surface bioactivation of materials.