The relationship between central obesity and bone mineral density: a Mendelian randomization study.

BACKGROUND: The relationship between obesity and osteoporosis is an important public health issue. The goal of this study was to investigate whether and to what extent central obesity traits affect bone mineral density (BMD). METHODS: We conducted a two-sample Mendelian randomization analysis. Genomewide significant single nucleotide polymorphisms associated with waist circumference, hip circumference, waist-to-hip ratio, waist circumference adjusted by body mass index (WCadjBMI), hip circumference adjusted by BMI (HCadjBMI) and waist-to-hip ratio adjusted by BMI (WHRadjBMI) were obtained from a large-scale database containing 224,459 samples. The BMD summary dataset was obtained from a UK Biobank database including 265,627 participants. RESULTS: The results provided strong evidence that the HCadjBMI trait was causally and negatively associated with BMD (ß: - 0.135, 95% CI - 0.216 to - 0.054; P = 0.001), while the WHR trait was causally and positively associated with BMD (ß: 0.194, 95% CI 0.062 to 0.325, P = 0.004). No significant effects were observed for other traits on BMD. CONCLUSIONS: This study indicates variations in the abilities of different central obesity traits to influence BMD. These results should be considered in further studies and public health measures on obesity and osteoporosis prevention strategies.

[Low-intensity pulsed ultrasound promotes extracellular matrix synthesis of human osteoarthritis chondrocytes].

Objective To investigate the effect of low-intensity pulsed ultrasound (LIPUS) on the extracellular matrix synthesis of human osteoarthritis (OA) chondrocytes and explore the underlying mechanism. Methods Human osteoarthritis chondrocytes were collected from abandoned articular cartilage. Then the cells were cultured and identified by toluidine blue staining and immunocytochemical staining of type 2 collagen. The passage 2 cells were randomly divided into 3 groups: control OA group, 30 mW/cm2 LIPUS-treated OA group, 30 mW/cm2 LIPUS combined with 5 µmol/L LY294002-treated OA group. LIPUS treatment was performed for 20 minutes per day, totally 7 days. The mRNA levels of Col2, aggrecan and matrix metalloprotease 13 (MMP-13) were determined by quantitative real-time PCR. The protein levels of Col2, aggrecan, Akt, p-Akt and MMP-13 were evaluated by Western blotting. Results Compared with the control OA group, the expressions of Col2 and aggrecan at both mRNA and protein levels significantly increased, and MMP-13 significantly reduced in the LIPUS-treated OA group. The p-Akt protein level was significantly elevated after LIPUS stimulation, but there was no significant difference in the Akt protein levels between the two groups. Moreover, LY294002, an inhibitor of PI3K/Akt, significantly suppressed the biological effect activated by LIPUS. Conclusion LIPUS enhances the synthesis and inhibits the degradation of the extracellular matrix in human osteoarthritis chondrocytes.