Diabetes mellitus (DM),a highly prevalent chronic metabolic disorder,can damage multiple organ systens.For instance,in the skeletal system,DM can lead to osteoporosis,delayed fracture healing or nonunion of fractures,which not only affects the prognosis of bone diseases and quality of life but also leads to huge medical and economic burden.The main reason of these skeletal complications is the disruption of the balance between bone formation and bone resorption,which leads to the disorders of bone metabolism.The mechanism of bone metabolism disorders in DM patients is determined by many biological factors,including high glucose (HG),oxidative stress,accumulation of advanced glycation end products (AGEs),insulin levels,inflammatory factors,growth factors,adipocytokines and hypaglycemic agents.Furthermore,as an important feature of DM,HG has obvious effects on bone metabolism mainly by acting on signal transduction pathways,including PI3K/Akt pathway,cAMP/PKA pathway,wnt pathway,MARK pathway,AMPK/mTOR/ULK1 pathway,BMP pathway,EphrinB2/EphB4 pathway,PPARγ pathway and NF-κB pathway.The above mentioned signal pathways regulate the proliferation,differentiation,apoptosis and aging of cells,such as bone marrow mesenchymal stem cells (BMSCs),osteoblasts and osteoclasts.These research areas have become the current hotspot for investigation.Although some studies has been conducted in these research areas,several limitations are still exist especially in vivo study.Thus,further studies are required.The present article reviews the effects of HG on bone metabolism signaling pathways.The purpose of this review is conducive to further understand the molecular mechanism of bone metabolism regulated by HG,and to provide theoretical basis and orientations for prevention and treatment of diabetic bone diseases.

Objective To investigate the effects of sodium butyrate on the activity of RAW264.7 cells and the osteoclast differentiation.Methods The RAW264.7 cells were treated by sodium butyrate at concentrations of 0,0.25,0.50,1.00,2.00,3.00,4.00 and 5.00 mmol/L,with 3 double pores for each concentration.The cytotoxicity of sodium butyrate on RAW264.7 cells was detected by a CCK-8 kit.The effects of sodium butyrate (0,0.25,0.50 and 1.00 mmol/L) on apoptosis of RAW264.7 cells were detected by Hoechst33342 staining.RAW264.7 cells were induced into osteoclasts by osteoclast differentiation factors.The experiment was carried out in 2 groups (n =3).After induced maturation,the experimental group was treated with 1.00 mmol/L sodium butyrate and the control medium was added only with the same volume of solvent.The number of osteoclasts and the area of bone resorption were observed and compared.The differentiation of RAW264.7 cells was detected by tartrate-resistant acid phosphatase (TRAP) staining.Western blotting was used to detect the effects of sodium butyrate (0,0.25,0.50 and 1.00 mmol/L) on NF-κB-related signaling pathway in RAW264.7 cells.Results Compared with the group of 0 mmol/L sodium butyrate,the activity of cells treated with 1.00,2.00,3.00,4.00 and 5.00 mmol/L sodium butyrate for 24 h was significantly decreased (P ＜ 0.05).Treatment with 1.00 mmol/L sodium butyrate for 24 h induced apoptosis.The number of osteoclasts in the control group and the experimental group were 9.33 ± 2.08 and 4.67 ± 1.16,respectively,showing a significant difference between the 2 groups (t =3.395,P =0.027).The percentages of bone resorption area in the control group and the experimental group were 52.43％ ± 5.38％ and 14.28％ ± 2.72％,respectively,also showing a significant difference between the 2 groups (t =10.970,P ＜ 0.001).Western blot results showed that,compared with other concentrations of sodium butyrate,treatment with 1 mmol/L sodium butyrate on RAW264.7 cells for 24 h led to an increase in the expression levels of cytoplasmic p65,B lymphoma-2 associated X protein and cleaved-caspase 3 and the acetylation of Histone H3 but a decrease in the phosphorylation level of α/β subunit of NF-κB kinase.Conclusions With the increased concentration of sodium butyratecan,the activity of NF-κB may be suppressed and the number of apoptotic cells may increase.1.00 mmol/L sodium butyrate can reduce osteoclast formation and bone resorption area.

IL-34 can promote osteoclast differentiation and activation, which may contribute to steroidinduced osteonecrosis of the femoral head (ONFH). Animal model was constructed in both BALB/c and IL-34 deficient mice to detect the relative expression of inflammation cytokines. Micro-CT was utilized to reveal the internal structure. In vitro differentiated osteoclast was induced by culturing bone marrow-derived macrophages with IL-34 conditioned medium or M-CSF. The relative expression of pro-inflammation cytokines, osteoclast marker genes, and relevant pathways molecules was detected with quantitative real-time RT-PCR, ELISA, and Western blot. Up-regulated IL-34 expression could be detected in the serum of ONFH patients and femoral heads of ONFH mice. IL-34 deficient mice showed the resistance to ONFH induction with the up-regulated trabecular number, trabecular thickness, bone value fraction, and down-regulated trabecular separation. On the other hand, inflammatory cytokines, such as TNF-α, IFN-γ, IL-6, IL-12, IL-2, and IL-17A, showed diminished expression in IL-34 deficient ONFH induced mice. IL-34 alone or works in coordination with M-CSF to promote osteoclastogenesis and activate ERK, STAT3, and non-canonical NF-κB pathways. These data demonstrate that IL-34 can promote the differentiation of osteoclast through ERK, STAT3, and non-canonical NF-κB pathways to aggravate steroid-induced ONFH, and IL-34 can be considered as a treatment target.

Objective:To investigate the consistency between the iodine-unstained area and the pathological size of endoscopic submucosal dissection (ESD) specimens of superficial esophageal cancer.Methods:A retrospective study was performed on data of 32 patients with superficial esophageal cancer who accepted ESD from May 2019 to April 2020 in the First Affiliated Hospital, Zhejiang University School of Medicine. The maximum transverse diameter and maximum longitudinal diameter of the iodine-unstained area were compared with the tumor pathological area. A size difference no more than 0.5 cm was considered as conformity, any difference between 0.5 and 1.0 cm was considered as non-conformity, and any difference no less than 1.0 cm was considered as serious non-conformity. At the same time, pink sign after spraying Lugo solution and the consistency of pink sign area with the iodine free area were observed.Results:A total of 32 patients with 33 lesions were enrolled in this study, including 23 males and 9 females and the age of the patients was 59.5±7.3 years. There were 19 (57.6%) lesions whose size of iodine-unstained area was consistent with the tumor pathological area. These 19 lesions were all positive for the pink sign, and the pink sign area overlapped with the iodine-unstained area. In addition, 4 (12.1%) iodine-unstained areas of the lesions did not match the size of the pathological area, and 10 (30.3%) iodine-unstained areas of the lesions were seriously inconsistent with the size of the pathological area. These 14 (42.4%) lesions were all positive for pink sign, and the pink sign area was significantly smaller than the iodine-unstained area. Among the 14 discordant lesions, 2 lesions underwent ESD according to the iodine-unstained area, which resulted in excessive resection and postoperative stenosis.Conclusion:Determining the extent of superficial esophageal cancer by iodine-unstained areas before ESD may lead to excessive resection of the lesions, which is related to the fact that the iodine-unstained areas of the lesions are sometimes significantly larger than the pink sign areas. Therefore, in order to achieve precise treatment, endoscopists can choose the iodine-unstained area with positive pink sign as the first choice for resection.