Huifang Liu

Effects of Pulsed Electromagnetic Fields on Bone Mass and Wnt/β-Catenin Signaling Pathway in Ovariectomized Rats

BACKGROUND AND AIMS The therapeutic effects of pulsed electromagnetic fields (PEMFs) on osteoporosis have been documented. However, the precise mechanisms by which PEMFs elicit these favorable biological responses are still not fully understood. This study aimed to systematically investigate the effects of PEMFs on bone mass and Wnt/β-catenin signaling pathway in ovariectomized rats. METHODS Thirty 3-month-old female Sprague Dawley rats were randomly assigned to one of three groups: sham-operated control (sham), ovariectomy (OVX), and ovariectomy with PEMFs treatment (PEMFs). One week following ovariectomy surgery, rats in the PEMFs group were exposed to PEMFs for 40 min/day, 5 days/week, for 12 weeks. RESULTS After 12-week interventions, serum 17β-estradiol and bone-specific alkaline phosphatase levels increased in the PEMFs group. Bone mineral density of the femur and the fifth lumbar vertebral body also increased in the PEMFs group. Histomorphometrical studies showed that PEMFs improved trabecular area, trabecular width, and trabecular number by 77.50%, 17.38% and 51.06%, respectively, and reduced trabecular separation by 44.28% compared with the OVX group. Biomechanical studies showed that PEMFs increased maximum load and energy to failure in the fifth lumbar vertebral body. Quantitative real-time RT-PCR analysis showed that PEMFs increased the mRNA expressions of Wnt3a, low-density lipoprotein receptor-related protein 5(LRP5), β-catenin, c-myc and runt-related gene 2 (Runx2), and reduced dickkopf1 (DKK1) in ovariectomized rats. However, mRNA expression of Axin2 was not affected by PEMFs. CONCLUSIONS PEMFs can prevent ovariectomy-induced bone loss and deterioration of bone microarchitecture and strength, at least partly, through activation of Wnt/β-catenin signaling pathway.

Coffee consumption and risk of fractures: a meta-analysis

Introduction Recent studies have indicated higher risk of fractures among coffee drinkers. To quantitatively assess the association between coffee consumption and the risk of fractures, we conducted this meta-analysis. Material and methods We searched MEDLINE and EMBASE for prospective studies reporting the risk of fractures with coffee consumption. Quality of included studies was assessed with the Newcastle Ottawa scale. We conducted a meta-analysis and a cumulative meta-analysis of relative risk (RR) for an increment of one cup of coffee per day, and explored the potential dose-response relationship. Sensitivity analysis was performed where statistical heterogeneity existed. Results We included 10 prospective studies covering 214,059 participants and 9,597 cases. There was overall 3.5% higher fracture risk for an increment of one cup of coffee per day (RR = 1.035, 95% CI: 1.019-1.052). Pooled RRs were 1.049 (95% CI: 1.022-1.077) for women and 0.910 (95% CI: 0.873-0.949) for men. Among women, RR was 1.055 (95% CI: 0.999-1.114) for younger participants, and 1.047 (95% CI: 1.016-1.080) for older ones. Cumulative meta-analysis indicated that risk estimates reached a stabilization level (RR = 1.035, 95% CI: 1.019-1.052), and it revealed a positive dose-response relationship between coffee consumption and risk of fractures either for men and women combined or women specifically. Conclusions This meta-analysis suggests an overall harm of coffee intake in increasing the risk of fractures, especially for women. But current data are insufficient to reach a convincing conclusion and further research needs to be conducted.

Pulsed electromagnetic field stimulates osteoprotegerin and reduces RANKL expression in ovariectomized rats

Pulsed electromagnetic field (PEMF) has been shown to increase bone mineral density in osteoporosis patients and prevent bone loss in ovariectomized rats. But the mechanisms through which PEMF elicits these favorable biological responses are still not fully understood. Receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) are cytokines predominantly secreted by osteoblasts and play a central role in differentiation and functional activation of osteoclasts. The purpose of this study was to investigate the effects of PEMF on RANKL and OPG expression in ovariectomized rats. Thirty 3-month-old female Sprague–Dawley rats were randomly divided into three groups: sham-operated control (Sham), ovariectomy control (OVX), and ovariectomy with PEMF treatment (PEMF). After 12-week interventions, the results showed that PEMF increased serum 17β-estradiol level, reduced serum tartrate-resistant acid phosphatase level, increased bone mineral density, and inhibited deterioration of bone microarchitecture and strength in OVX rats. Furthermore, PEMF could suppress RANKL expression and improve OPG expression in bone marrow cells of OVX rats. In conclusion, this study suggests that PEMF can prevent ovariectomy-induced bone loss through regulating the expression of RANKL and OPG.

Pulsed electromagnetic fields on postmenopausal osteoporosis in Southwest China: a randomized, active-controlled clinical trial.

A randomized, active-controlled clinical trial was conducted to examine the effect of pulsed electromagnetic fields (PEMFs) on women with postmenopausal osteoporosis (PMO) in southwest China. Forty-four participants were randomly assigned to receive alendronate or one course of PEMFs treatment. The primary endpoint was the mean percentage change in bone mineral density of the lumbar spine (BMDL), and secondary endpoints were the mean percentage changes in left proximal femur bone mineral density (BMDF), serum 25OH vitamin D3 (25(OH)D) concentrations, total lower-extremity manual muscle test (LE MMT) score, and Berg Balance Scale (BBS) score. The BMDL, BMDF, total LE MMT score and BBS score were recorded at baseline, 5, 12, and 24 weeks. Serum concentrations of 25(OH)D were measured at baseline and 5 weeks. Using a mixed linear model, there was no significant treatment difference between the two groups in the BMDL, BMDF, total LE MMT score, and BBS score (P ≥ 0.05). For 25(OH)D concentrations, the effects were also comparable between the two groups (P ≥ 0.05) with the Mann-Whitneys U-test. These results suggested that a course of PEMFs treatment with specific parameters was as effective as alendronate in treating PMO within 24 weeks.

Electroacupuncture prevents ovariectomy-induced osteoporosis in rats: a randomised controlled trial

Background Electroacupuncture (EA) treatment has been shown to increase bone mineral density (BMD) in ovariectomised (OVX) rats; however, the underlying mechanisms remain unclear. Objective To systematically evaluate the effects of EA on OVX rats and the Wnt/β-catenin signalling pathway. Methods Three-month-old female Sprague–Dawley rats were randomly divided into three different groups (n=10 each): sham operated control (sham operated), ovariectomy (OVX) and ovariectomy with EA treatment (OVX+EA). Rats in the OVX+EA group received 12-week EA treatments. Results Serum bone-specific alkaline phosphatase level (p<0.01), BMD of the proximal femoral metaphysis and the fifth lumbar (L5) vertebral body (both, p<0.05) and maximum load and energy to failure of L5 vertebral body (both p<0.01) were significantly higher in the OVX+EA group than in the OVX group. Trabecular area, trabecular width and trabecular number were significantly higher in the OVX+EA group by 66.9%, 29.2% and 30.3%, respectively, than in the OVX group (all, p<0.01). Trabecular separation was 31.9% lower in the OVX+EA group than in the OVX group (p<0.01). Quantitative real-time reverse transcription polymerised chain reaction indicated that the expressions of mRNAs for low-density lipoprotein receptor-related protein 5 and β-catenin were significantly increased in the OVX+EA group, as compared with the OVX group (p<0.01 and p<0.05, respectively). Conclusion This study demonstrates that EA can prevent OVX-induced bone loss and deterioration of bone architecture and strength by stimulating the Wnt/β-catenin signalling pathway. These findings suggest that EA may bet a promising adjunct method for inhibiting OVX-induced osteoporosis in clinical settings.

Vitamin D receptor gene polymorphisms and risk of osteoarthritis: A meta-analysis

The vitamin D receptor (VDR) gene polymorphisms have been reported to be involved in the development of many musculoskeletal disorders, including osteoarthritis (OA). However, results were inconsistent and there is no definite conclusion regarding the association between any VDR polymorphism and the risk of OA. In this study, we conducted a meta-analysis to determine whether BsmI, TaqI, and ApaI polymorphisms in the VDR gene are associated with OA susceptibility. Literature research was performed using PubMed and EMBASE databases. Studies illustrating the association between the three VDR polymorphisms and OA were included, and their qualities were assessed using Newcastle–Ottawa scale. Eight eligible studies, recruiting 1626 cases and 2024 controls were identified. Their methodological qualities were generally good, with scores ranging from 6 to 8 points. However, throughout all summary analyses, which were performed for multiple categories and on four contrasts (allele contrast, contrast of homozygotes, recessive and dominant models), none of the VDR BsmI, TaqI, and ApaI gene polymorphisms were found to be significantly associated with the risk of OA. On the other hand, there was no significant publication bias. Results from this meta-analysis suggested that the VDR BsmI, TaqI, and ApaI gene polymorphisms might not be important predictors of OA. More studies further investigating these associations, especially taking into account of gene–gene, gene–environment interactions, and other confounding factors are warranted.

The hemorheological safety of pulsed electromagnetic fields in postmenopausal women with osteoporosis in southwest China: A randomized, placebo controlled clinical trial

Apart from medications, pulsed electromagnetic fields (PEMFs) are used to treat osteoporosis nowadays. However studies on hemorheological safety of PEMFs were scarce. This randomized, placebo controlled clinical trial assessed whether PEMFs could lead to significant hemorheological changes. Fifty-five postmenopausal women were randomly assigned to receive placebo or PEMFs. Venous blood samples were collected at baseline and after treatment to measure 14 hemorheological determinants. Independent samples t-test, paired samples t-test and chi-squared tests were performed respectively. Relationships between variables were determined by Pearson correlation analysis. Multiple linear stepwise regression analysis was used to explore predictors of selected determinants. No significant differences existed between the placebo and PEMFs groups for any of the 14 hemorheological determinants (P>0.05) or the percentage of patients with hemorheological determinant within reference range (P>0.05). Hematocrit was found to be correlated with BMI (P=0.007). The most significant predictor of blood reduced viscosity at low shear rate was blood viscosity at low shear rate. And blood reduced viscosity at high shear rate was the most important predictor of plasma viscosity. These results showed, compared with placebo, PEMFs treatment of postmenopausal osteoporosis was not associated with adverse changes in hemorheological determinants, which may contribute to venous thromboembolism.