Association between Serum Selenium Level and the Presence of Diabetes Mellitus: A Meta-Analysis of Observational Studies

BACKGROUND: Epidemiological studies have suggested an association between selenium (Se) and diabetes mellitus (DM). However, different studies have reported conflicting results. Therefore, we performed a comprehensive meta-analysis to clarify the impact of Se on DM. METHODS: We searched the PubMed database for studies on the association between Se and DM from inception to June 2018. RESULTS: Twenty articles evaluating 47,930 participants were included in the analysis. The meta-analysis found that high levels of Se were significantly associated with the presence of DM (pooled odds ratios [ORs], 1.88; 95% confidence interval [CI], 1.44 to 2.45). However, significant heterogeneity was found (I2 =82%). Subgroup analyses were performed based on the Se measurement methods used in each study. A significant association was found between high Se levels and the presence of DM in the studies that used blood (OR, 2.17; 95% CI, 1.60 to 2.93; I2 =77%), diet (OR, 1.61; 95% CI, 1.10 to 2.36; I2 =0%), and urine (OR, 1.49; 95% CI, 1.02 to 2.17; I2 =0%) as samples to estimate Se levels, but not in studies on nails (OR, 1.24; 95% CI, 0.52 to 2.98; I2 =91%). Because of significant heterogeneity in the studies with blood, we conducted a sensitivity analysis and tested the publication bias. The results were consistent after adjustment based on the sensitivity analysis as well as the trim and fill analysis for publication bias. CONCLUSION: This meta-analysis demonstrates that high levels of Se are associated with the presence of DM. Further prospective and randomized controlled trials are warranted to elucidate the link better.

Inhibition of Osteoclast Differentiation and Bone Resorption by Poria cocos Wolf Extract / 대한골다공증학회지

OBJECTIVES: Osteoclast differentiation and bone resorption are considered a potential therapeutic target to the treatment of erosive bone diseases, including osteoporosis and rheumatoid arthritis. Poria cocos Wolf (PCW), commonly used herbal medicine, has previously been reported to induce anti-inflammatory effect and anti-cancer effect, and to modulate immunologic responses. However, the effects of PCW on osteoclasts, and its detailed mechanisms are not proven. Therefore, we examined the inhibitory mechanism of PCW on osteoclast differentiation and bone resorption. MATERIALS AND METHODS: To analyze the effects of PCW on osteoclast differentiation, we examined osteoclast differentiation in bone marrow macrophages (BMMs) treated with or without of PCW by TRAP staining. The expression of c-Fos, NFATc1, TRAP and OSCAR mRNA was determined by RT-PCR and the protein levels of c-Fos, NFATc1, p38, ERK, JNK, Akt and IkappaB were assessed by western blot. Also, we evaluated the effect of PCW on bone resorption using hydroxyapatite plate. RESULTS: PCW significantly inhibited RANKL-mediated osteoclast differentiation without any evidence of cytotoxicity. We founded that PCW strongly inhibited RANKL-induced osteoclast formation when added during the early stage of cultures, suggesting that PCW acts on osteoclast precursors to inhibit RANKL/RANK signaling. Among the RANK signaling pathways, PCW inhibited the phosphorylation of p38 and JNK, also inhibited RANKL-induced expression of c-Fos, NFATc1, TRAP and OSCAR. In addition, PCW suppressed the bone resorption of mature osteoclasts. CONCLUSIONS: These findings suggest that PCW may be a potential novel drug for bone disorders by targeting the differentiation of osteoclasts as well as their functions.