ABSTRACT
The fabrication of customized implants by additive manufacturing has allowed continued development of the personalized medicine field. Herein, a 3D-printed bioabsorbable poly (lactic acid) (PLA)- ß-tricalcium phosphate (TCP) (10 wt %) composite has been modified with CeO2 nanoparticles (CeNPs) (1, 5 and 10 wt %) for bone repair. The filaments were prepared by melt extrusion and used to print porous scaffolds. The nanocomposite scaffolds possessed precise structure with fine print resolution, a homogenous distribution of TCP and CeNP components, and mechanical properties appropriate for bone tissue engineering applications. Cell proliferation assays using osteoblast cultures confirmed the cytocompatibility of the composites. In addition, the presence of CeNPs enhanced the proliferation and differentiation of mesenchymal stem cells; thereby, increasing alkaline phosphatase (ALP) activity, calcium deposition and bone-related gene expression. Results from this study have shown that the 3D printed PLA-TCP-10%CeO2 composite scaffold could be used as an alternative polymeric implant for bone tissue engineering applications: avoiding additional/revision surgeries and accelerating the regenerative process.
ABSTRACT
ABSTRACT: Nunes, ACCA, Cattuzzo, MT, Faigenbaum, AD, and Mortatti, AL. Effects of integrative neuromuscular training and detraining on countermovement jump performance in youth volleyball players. J Strength Cond Res 35(8): 2242-2247, 2021-The purpose of this study was to analyze the effect of integrative neuromuscular training (INT) on countermovement vertical jump height (CVJH) performance in youth volleyball players before and after a detraining period. Thirty-two novice volleyball players were cluster randomized into 2 groups: intervention group-INT (age: 13.1 ± 0.4 years; body mass: 55.3 ± 12.1 kg; and height: 161.1 ± 6.4 cm) and control group-CON (age: 12.8 ± 0.7 years; body mass: 51.8 ± 13.6 kg; and height: 160.1 ± 10.7 cm). The subjects were evaluated for somatic maturation (years from peak height velocity) and for CVJH performance at 4 time points during the 20-week study period: baseline, 6 weeks of INT, 12 weeks of INT, and 8 weeks after INT (detraining). The analysis used repeated-measures analysis of variance and Bonferroni post hoc test to identify possible differences in the CVJH delta in both groups. Spearman correlation was performed to verify the association between the values of the vertical jump tests and maturational levels found. The INT showed a significant improvement in the CVJH from baseline to 12 weeks and maintained training-induced gains after detraining period (p > 0.001). Significant increase in CVJH was found in the percentage of change (Δ%) from baseline to 6 weeks (p < 0.005), 12 weeks (p < 0.001), and detraining (p < 0.001) in INT compared with the CON. The results of this study indicate that INT was able to improve CVJH performance in novice youth volleyball players and these gains were sustained during the detraining period. These findings indicate that regular participation in supervised INT can enhance jumping performance in young volleyball players, and that this type of neuromuscular program may be particularly beneficial for youth with limited fundamental motor skill performance.
Subject(s)
Athletic Performance , Volleyball , Adolescent , Child , Humans , Muscle StrengthABSTRACT
Angiogenesis, a crucial process in tumor progression, is mainly regulated by vascular endothelial growth factor (VEGF) and its receptor, VEGFR2. Studies have shown the interaction between α2ß1 integrin, a collagen receptor, and VEGFR2 in VEGF-driven angiogenesis in vitro and in vivo. Alternagin-C (ALT-C), an ECD-disintegrin-like protein from Bothrops alternatus snake venom, has high affinity for α2ß1 integrin and shows antiangiogenic activity in concentrations higher than 100 nM. Despite previous results, its mechanism of action on angiogenic signaling pathways has not been addressed. Here we evaluate the antiangiogenic activity of ALT-C in human umbilical vein endothelial cells (HUVECs) associated or not with VEGF, as well as its interference in the α2ß1/VEGFR2 crosstalk. ALT-C (1000 nM) affected actin cytoskeleton, decreased the number of cell filopodia, and strongly inhibited HUVEC tube formation, adhesion to type I collagen and cell migration. Down-regulation of α2ß1/VEGFR2 crosstalk by ALT-C decreased the protein content and phosphorylation of VEGFR2 and ß1 integrin subunit, inhibited ERK 1/2 and PI3K signaling and regulated FAK/Src and paxillin pathways. Furthermore, ALT-C increased the content of the autophagic markers LC3B and Beclin-1 in the presence of VEGF, which is associated with decreased angiogenesis. In conclusion, we suggest that ALT-C, after binding to α2ß1 integrin, inhibits VEGF/VEGFR2 signaling, which results in impaired angiogenesis. These results demonstrate that ALT-C may be a potential candidate for the development of antiangiogenic therapies for tumor and metastasis treatment and help to understand the complexity and fundamental role of integrin inhibition in the tumor microenvironment.
