ObjectiveTo systematically review vitamin D nutritional status among children and adolescents in China.MethodsCNKI, CBM, WanFang Data, VIP and PubMed databases were electronically searched to collect cross-sectional studies on vitamin D nutritional status among children and adolescents in China from inception to September, 2020. Two reviewers independently screened literature, extracted data and assessed risk of bias of included studies. Meta-analysis was then performed by using Stata 11.0 software.ResultsA total of 23 cross-sectional studies involving 38 047 total sample size were included.The results of meta-analysis showed that the combined vitamin D deficiency rate was 27.9% (95%CI 21.9% to 33.8%), and the inadequate rate was 31.6% (95%CI 25.7% to 37.6%).Subgroup analysis showed that vitamin D deficiency rate of females was higher than that of males (25.3% vs. 22.5%). The vitamin D deficiency rate of children aged 10 to 18 was higher than those aged 6 to 9 (44.9% vs. 32.9%). The vitamin D deficiency rate of children in the north was higher than that in south (36.1% vs. 14.8%). The vitamin D deficiency rate from 2015 to 2018 was higher than that from 2011 to 2014 (34.9% vs. 17.6%). In addition, the vitamin D deficiency rate ofurban children was higher than that of rural children (29.9% vs. 24.9%).ConclusionsThe incidence of vitamin D deficiency among children and adolescents is high in China. Due to limited quality and quantity of the included studies, more high quality studies are required to verify above conclusions.
Objective To investigate the influenceof insulin-like growth factor-I (IGF-I) on biological characteristics of articular chondrocytes cultured in vitro of rabbits. Methods Monolayer articular chondrocytes of 4week old rabbits were cultured in medium with IGF-I, at the concentrations of 3, 10, 30, 100, and300ng/ml. The DNA content in cells and glucuronic acid content in matrix were detected on the 2nd, 4th, 6th days after culture. Results The DNA content in cells and the glucuronic acid content in matrix in articular chondrocytes cultured in medium with IGF-I at concentrations of 3-300ng/ml were all significantly higher than those in control group (P＜0.01), which reached the peak at the concentrations of 30-100mg/ml on the 4th day. Conclusion IGF-I could obviously promote theproliferation of articular chondrocytes in vitro, and there exist time-dependent and dose-dependent effect.