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| 1 | Connexin 43 hemichannels protect bone loss during estrogen deficiency显示文摘Estrogen deficiency in postmenopausal women is a major cause of bone loss,resulting in osteopenia,osteoporosis,and a high risk for bone fracture.Connexin 43 (Cx43) hemichannels (HCs) in osteocytes play an important role in osteocyte viability,bone formation,and remodeling.We showed here that estrogen deficiency reduced Cx43 expression and HC function.To determine if functional HCs protect osteocytes and bone loss during estrogen deficiency,we adopted an ovariectomy model in wild-type (WT) and two transgenic Cx43 mice:R76W (dominant-negative mutant inhibiting only gap junction channels) and Cx43 Δ130–136 (dominant-negative mutant compromising both gap junction channels and HCs).The bone mineral density (BMD),bone structure,and histomorphometric changes of cortical and trabecular bones after ovariectomy were investigated.Our results showed that the Δ130–136 transgenic cohort had greatly decreased vertebral trabecular bone mass compared to WT and R76W mice,associated with a significant increase in the number of apoptotic osteocyte and empty lacunae.Moreover,osteoclast surfaces in trabecular and cortical bones were increased after ovariectomy in the R76W and WT mice,respectively,but not in Δ130–136 mice.These data demonstrate that impairment of Cx43 HCs in osteocytes accelerates vertebral trabecular bone loss and increase in osteocyte apoptosis,and further suggest that Cx43 HCs in osteocytes protect trabecular bone against catabolic effects due to estrogen deficiency. | Liang Ma Rui Hua Yi Tian Hongyun Cheng Roberto Jose Fajardo Joseph J. Pearson Teja Guda Daniel Brian Shropshire Sumin Gu Jean X. Jiang | 2019 | Bone Research2019，7，2： | 11 |
| 2 | Sintering effects on chemical and physical properties of bioactive ceramics显示文摘The objective of this study was to characterize the chemical and physical properties of bioactive ceramics prepared from an aqueous paste containing hydroxyapatite(HA)and beta tri-calcium phosphate(β-TCP).Prior to formulating the paste,HA andβ-TCP were calcined at 800℃and 975℃(11 h),milled,and blended into 15%/85%HA/β-TCP volume-mixed paste.Fabricated cylindrical rods were subsequently sintered to 900℃,1100℃or 1250℃.The sintered specimens were characterized by helium pycnometry,X-ray diffraction(XRD),Fourier transform-infrared(FT-IR),and inductively coupled plasma(ICP)spectroscopy for evaluation of porosity,crystalline phase,functional-groups,and Ca:P ratio,respectively.Mechanical properties were assessed via 3-point bending and diametral compression.Qualitative microstructural evaluation using scanning electron microscopy(SEM)showed larger pores and a broader pore size distribution(PSD)for materials sintered at 900℃and 1100℃,whereas the 1250℃samples showed more uniform PSD.Porosity quantification showed significantly higher porosity for materials sintered to 900℃and 1250℃(p<0.05).XRD indicated substantial deviations from the 15%/85%HA/β-TCP formulation following sintering where lower amounts of HA were observed when sintering temperature was increased.Mechanical testing demonstrated significant differences between calcination temperatures and different sintering regimes(p<0.05).Variation in chemical composition and mechanical properties of bioactive ceramics were direct consequences of calcination and sintering. | Lukasz WITEK James SMAY Nelson R.F.A.SILVA Teja GUDA Joo L.ONG Paulo G.COELHO | 2013 | Journal of Advanced Ceramics2013，2，3： | 0 |
| 3 | Osteocytes regulate bone anabolic response to mechanical loading in male mice via activation of integrinα5显示文摘Physical mechanical stimulation can maintain and even increase bone mass.Here,we report an important role of osteocytic integrinα5 in regulating the anabolic response of bone to mechanical loading using an Itga5 conditional gene knockout(cKO)mouse model.Integrinα5 gene deletion increased apoptotic osteocytes and reduced cortical anabolic responses to tibial compression including decreased endosteal osteoblasts and bone formation,and increased endosteal osteoclasts and bone resorption,contributing to the decreased bone area fraction and biomechanical properties,leading to an enlarged bone marrow area in cKO mice.Similar disruption of anabolic responses to mechanical loading was also detected in cKO trabecular bone.Moreover,integrinα5 deficiency impeded load-induced Cx43 hemichannel opening,and production and release of PGE2,an anabolic factor,resulting in attenuated effects of the loading on catabolic sclerostin(SOST)reduction and anabolicβ-catenin increase.Together,this study shows an indispensable role of integrinα5 in osteocytes in the anabolic action of mechanical loading on skeletal tissue through activation of hemichannels and PGE2-evoked gene expression.Integrinα5 could act as a potential new therapeutic target for bone loss,especially in the elderly population with impeded mechanical sensitivity. | Dezhi Zhao Rui Hua Manuel A.Riquelme Hongyun Cheng Teja Guda Huiyun Xu Sumin Gu Jean X.Jiang | 2022 | Bone Research2022，10，4： | 0 |
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