Calcitonin gene-related peptide attenuated discogenic low back pain in rats possibly via inhibiting microglia activation.

Discogenic low back pain (DLBP) is a multifactorial disease and associated with intervertebral disc degeneration. Calcitonin gene-related protein (CGRP) plays a critical role in pain processing, while the role in DLBP remains unclear. This study aims to investigate the anti-nociceptive role and related mechanisms of CGRP in DLBP. Here we established the DLBP rat and validated the model using histology and radiography. Minocycline, a microglial inhibitor, and CGRP were intrathecally injected and the behavioral test was performed to determine hyperalgesia. Further, BV2 microglial cells and microglial activation agent lipopolysaccharide (LPS) were employed for the in vitro experiment. We observed obvious lumbar intervertebral disc degeneration and hyperalgesia at 12 weeks postoperation in DLBP group, with significantly activated microglia in the spinal cord. CGRP treatment significantly inhibited the upregulation of proinflammatory cytokines and NLRP3/caspase-1 expression induced by LPS in BV2 cells, whereas treatment with CGRP alone had little effect on BV2 cells. The intrathecal injection of CGRP into DLBP rats relieved mechanical and thermal hyperalgesia, reverted the microglial activation and decreased the expression of NLRP3/caspase-1, similar to the effects produced by minocycline. Our results provide evidence that microglial activation in the spinal cord play a key role in hyperalgesia in DLBP rats. CGRP alleviates DLBP induced hyperalgesia and inhibits microglial activation in the spinal cord. Regulation of CGRP and microglial activation may provide a new strategy for ameliorating DLBP.

Network pharmacology-based and molecular docking-based analysis of You-Gui-Yin for the treatment of osteonecrosis of the femoral head.

You-Gui-Yin (YGY) is a classic prescription for warming up kidney-Yang and filling in kidney essence in traditional Chinese medicine, and has been used to treat osteonecrosis of the femoral head (ONFH) effectively. However, the underlying mechanisms are still unknown. This study is aimed at exploring the possible mechanisms of action of the YGY in the treatment of ONFH based on network pharmacology and molecular docking. TCMSP was used to screen the active components and targets of YGY. The disease targets of ONFH were collected in several public databases. The protein-protein interaction (PPI) Network was constructed using the STRING platform. The Metascape database platform was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The key active components and core target proteins of YGY in the treatment of ONFH were verified by the molecular docking. 120 active components were obtained from YGY, among which 73 components were hit by the 117 drug-disease intersection targets. Key effective components included quercetin, kaempferol, beta-sitosterol, glycitein, beta-carotene, and so on. Core target proteins included ALB, AKT1, TNF, IL6, TP53, and so on. According to GO and KEGG analyses, there were 1762 biological processes, 94 cellular component, 138 molecular function and 187 signaling pathways involved. we selected the top 20 biological processes (BP), cellular components (CC), molecular functions (MF) and signaling pathways to draw the heat maps, showing that Lipid and atherosclerosis signaling pathway, IL-17 signaling pathway, HIF-1 signaling pathway, relaxin signaling pathway and MAPK signaling pathway and other pathways may play a key role in the treatment of ONFH by YGY. The results of molecular docking showed that key effective components and corresponding core target proteins exhibited the good binding activity. YGY can treat ONFH through multicomponents, multitargets, and multipathways, which provides a reference for the subsequent research, development of targeted drugs and clinical application.

Neuropeptide Y-Mediated Gut Microbiota Alterations Aggravate Postmenopausal Osteoporosis.

Postmenopausal osteoporosis (PMO) is often accompanied by neuroendocrine changes in the hypothalamus, which closely associates with the microbial diversity, community composition, and intestinal metabolites of gut microbiota (GM). With the emerging role of GM in bone metabolism, a potential neuroendocrine signal neuropeptide Y (NPY) mediated brain-gut-bone axis has come to light. Herein, it is reported that exogenous overexpression of NPY reduced bone formation, damaged bone microstructure, and up-regulated the expressions of pyroptosis-related proteins in subchondral cancellous bone in ovariectomized (OVX) rats, but Y1 receptor antagonist (Y1Ra) reversed these changes. In addition, it is found that exogenous overexpression of NPY aggravated colonic inflammation, impaired intestinal barrier integrity, enhanced intestinal permeability, and increased serum lipopolysaccharide (LPS) in OVX rats, and Y1Ra also reversed these changes. Most importantly, NPY and Y1Ra modulated the microbial diversity and changed the community composition of GM in OVX rats, and thereby affecting the metabolites of GM (e.g., LPS) entering the blood circulation. Moreover, fecal microbiota transplantation further testified the effect of NPY-mediated GM changes on bone. In vitro, LPS induced pyroptosis, reduced viability, and inhibited differentiation of osteoblasts. The study demonstrated the existence of NPY-mediated brain-gut-bone axis and it might be a novel emerging target to treat PMO.

Metal-polyDNA nanoparticles reconstruct osteoporotic microenvironment for enhanced osteoporosis treatment.

Current clinical approaches to osteoporosis primarily target osteoclast biology, overlooking the synergistic role of bone cells, immune cells, cytokines, and inorganic components in creating an abnormal osteoporotic microenvironment. Here, metal-polyDNA nanoparticles (Ca-polyCpG MDNs) composed of Ca2+ and ultralong single-stranded CpG sequences were developed to reconstruct the osteoporotic microenvironment and suppress osteoporosis. Ca-polyCpG MDNs can neutralize osteoclast-secreted hydrogen ions, provide calcium repletion, promote remineralization, and repair bone defects. Besides, the immune-adjuvant polyCpG in MDNs could induce the secretion of osteoclastogenesis inhibitor interleukin-12 and reduce the expression of osteoclast function effector protein to inhibit osteoclast differentiation, further reducing osteoclast-mediated bone resorption. PPi4- generated during the rolling circle amplification reaction acts as bisphosphonate analog and enhances bone targeting of Ca-polyCpG MDNs. In ovariectomized mouse and rabbit models, Ca-polyCpG MDNs prevented bone resorption and promoted bone repair by restoring the osteoporotic microenvironment, providing valuable insights into osteoporosis therapy.

Bibliometric and visualized analysis of exercise and osteoporosis from 2002 to 2021.

Background: Bibliometric analysis was designed to investigate a systematic understanding of developments in exercise and osteoporosis research over the past 20 years. Methods: Relevant publications from the Web of Science Core Collection were downloaded on April 26, 2022. CiteSpace, VOSviewer, and the online bibliometric analysis platform were used to conduct this scientometric study. Results: A total of 5518 publications were in 1202 academic journals with 137405 co-cited references in by 5637 institutions from 98 countries/regions. The country leading the research was the USA. The University of Melbourne was the most active institution. Osteoporosis International was the most productive journal concerning exercise and osteoporosis research. According to the burst references, "low-level vibration," "high-frequency" and "resistance exercise" have been recognized as the hotspots research in the domain. The keywords co-occurrence analysis identified "skeletal muscle," "sarcopenia" and "mesenchymal stem cell" as the important future research directions. Conclusion: This study was the first comprehensive metrological and statistical analysis of exercise and osteoporosis research over the past 20 years. Our findings would provide guidance to understand the research frontiers and hot directions in the near future.

Neuropeptide Y and receptors are associated with the pyroptosis of nucleus pulposus in aging and degenerative intervertebral discs of rats.

The neuropeptide Y(NPY) mediates bone metabolism and the degradation of cartilage in the peripheral nervous system. However, its role in the intervertebral disc degeneration (IDD) is less clear and warrant further study. The process of IDD has always been accompanied by inflammatory response and pyroptosis of nucleus pulposus cells (NPCs). The aim of this study was to investigate the relationship between NPY, Y1R, Y2R and pyroptosis in aging and degenerative discs and the direct effect of NPY on NPCs. First, we have assessed NPY, Y1R, Y2R and the expression of pyroptosis related protein in the immature (6 weeks), mature (16 weeks), aged (54 weeks), and degenerated discs. As part of our studies, we also have evaluated pyroptotic changes in the NPCs, induced by exposure to NPY. Our results suggested that compared with natural aging discs, the degenerative discs showed the high expression of NPY, Y1R and Y2R. Correlation analysis showed that the level of NPY and Y1R in degenerative discs were positively correlated with GSDMD, whereas there was no significant correlation between Y2R and GSDMD. In vitro, NPY treatment stimulated the activation of caspase-1-dependent pyroptosis of NPCs. However, Y1R antagonist inhibited NPY-induced pyroptosis of NPCs. Western blot confirmed that Y1R antagonist decreased the level of cleaved.GSDMD and caspase-1 in NPCs. In conclusion, our results indicated that compared with natural aging discs, the degenerated discs showed the high expression of NPY, Y1R and Y2R. NPY-Y1R involve the IDD development by the regulation of pyroptosis in the NPCs. Regulating the function of NPY may be a promising strategy for IDD treatment.

Potential of [11C]UCB-J as a PET tracer for islets of Langerhans.

Biomarkers for the measurement of islets of Langerhans could help elucidate the etiology of diabetes. Synaptic vesicle glycoprotein 2 A (SV2A) is a potential marker reported to be localized in the endocrine pancreas. [11C]UCB-J is a novel positron emission tomography (PET) radiotracer that binds to SV2A and was previously evaluated as a synaptic marker in the central nervous system. Here, we evaluated whether [11C]UCB-J could be utilized as a PET tracer for the islets of Langerhans in the pancreas by targeting SV2A. The mRNA transcription of SV2A was evaluated in human isolated islets of Langerhans and exocrine tissue. In vitro autoradiography was performed on pancreas and brain sections from rats and pigs, and consecutive sections were immunostained for insulin. Sprague-Dawley rats were examined with PET-MRI and ex vivo autoradiography at baseline and with administration of levetiracetam (LEV). Similarly, pigs were examined with dynamic PET-CT over the pancreas and brain after administration of [11C]UCB-J at baseline and after pretreatment with LEV. In vivo radioligand binding was assessed using a one-compartment tissue model. The mRNA expression of SV2A was nearly 7 times higher in endocrine tissue than in exocrine tissue (p < 0.01). In vitro autoradiography displayed focal binding of [11C]UCB-J in the pancreas of rats and pigs, but the binding pattern did not overlap with the insulin-positive areas or with ex vivo autoradiography. In rats, pancreas binding was higher than that in negative control tissues but could not be blocked by LEV. In pigs, the pancreas and brain exhibited accumulation of [11C]UCB-J above the negative control tissue spleen. While brain binding could be blocked by pretreatment with LEV, a similar effect was not observed in the pancreas. Transcription data indicate SV2A to be a valid target for imaging islets of Langerhans, but [11C]UCB-J does not appear to have sufficient sensitivity for this application.

[Ultrasound-guided closed reduction and kirschner wires internal fixation for the treatment of Kilfoyleâ ¡and â ¢ medial condylar fracture of humerus in children].

OBJECTIVE: To explore clinical effectiveness and safety of ultrasound-guided closed reduction and K-wires internal fixation in treating of Kilfoyle Ⅱand Ⅲ medial condylar fracture of humerus in children. METHODS: Clinical data of 32 children with medial condylar fracture of humerus treated with closed reduction and internal fixation with K-wires under the guidance of ultrasound were retrospectively analyzed from January 2014 to August 2019, including 23 males and 9 females, age ranged from 3.2 to 12.8 years old with an average of (8.3±2.1) years old;According to classification of Kilfoyle, 12 patients classified to typeⅡ and 20 patients were type Ⅲ;5 patients combined with elbow dislocation;the time from injury to operation ranged from 1 to 5 days with an average of (3.1±1.3) days. Radiological evaluation of treatment results and complications were observed. At the final follow up, Mayo elbow performance score(MEPS) was used to evaluate elbow function. And humerus-ulna angle on the affect side and healthy side were measured and compared. RESULTS: All patients were followed up from 8 to 26 months with an average of(19.3±5.5) months. All fractures were healed well, the healing time ranged from 4 to 6 weeks with an average of (4.5±0.5) weeks. No infection, vascular and nerve injury, bone nonunion, trochlear necrosis, cubitus varus or valgus deformity were occurred. According to Mayo scoring, all patients were assessed as excellent. There was no significant difference in angle of humerus-ulna between affectedside (9.5±3.6)° and healthy side (9.1±3.5)°, and no difference in MEPS scores between affected side(95.3±2.5) and healthy side(96.3±2.2)(P>0.05). CONCLUSION: For Kilfoyle typeⅡand Ⅲ medial condylar fracture of humerus in children, closed reduction and internal fixation with K-wire under ultrasound guidance is a safe and effective method, and could promote in further.

SIRT6 enhances telomerase activity to protect against DNA damage and senescence in hypertrophic ligamentum flavum cells from lumbar spinal stenosis patients.

Lumbar spinal stenosis (LSS) is a condition wherein patients exhibit age-related fibrosis, elastin-to-collagen ratio reductions, and ligamentum flavum hypertrophy. This study was designed to assess the relationship between SIRT6 and telomerase activity in hypertrophic ligamentum flavum (LFH) cells from LSS patients. We observed significant reductions in SIRT6, TPP1, and POT1 protein levels as well as increases in telomerase reverse transcriptase (TERT) levels and telomerase activity in LFH tissues relative to non- hypertrophic ligamentum flavum (LFN) tissues. When SIRT6 was overexpressed in these LFH cells, this was associated with significant increases in telomerase activity and a significant reduction in fibrosis-related protein expression. These effects were reversed, however, when telomerase activity was inactivated by hTERT knockdown in these same cells. SIRT6 overexpression was further found to reduce the frequency of senescence-associated ß-galactosidase (SA-ß-Gal)-positive LFH cells and to decrease p16, MMP3, and L1 mRNA levels and telomere dysfunction-induced foci (TIFs) in LFH cells. In contrast, hTERT knockdown-induced telomerase inactivation eliminated these SIRT6-dependent effects. Overall, our results indicate that SIRT6 functions as a key protective factor that prevents cellular senescence and telomere dysfunction in ligamentum flavum cells, with this effect being at least partially attributable to SIRT6-dependent telomerase activation.

Neuropeptide Y1 receptor antagonist promotes osteoporosis and microdamage repair and enhances osteogenic differentiation of bone marrow stem cells via cAMP/PKA/CREB pathway.

Osteoporosis is a common metabolic bone disorder in the elderly population. The accumulation of bone microdamage is a critical factor of osteoporotic fracture. Neuropeptide Y (NPY) has been reported to regulated bone metabolism through Y1 receptor (Y1R). In this study the effects and mechanisms of Y1R antagonist on prevention for osteoporosis were characterized. In the clinical experiment, compared with osteoarthritis (OA), osteoporosis (OP) showed significant osteoporotic bone microstructure and accumulation of bone microdamage. NPY and Y1R immunoreactivity in bone were stronger in OP group, and were both correlated with bone volume fraction (BV/TV). In vivo experiment, Y1R antagonist significantly improved osteoporotic microstructure in the ovariectomized (OVX) rats. And Y1R antagonist promoted RUNX2, OPG and inhibit RANKL, MMP9 in bone marrow. In vitro cell culture experiment, NPY inhibited osteogenesis, elevated RANKL/OPG ratio and downregulated the expression of cAMP, p-PKAs and p-CREB in BMSCs, treated with Y1R antagonist or 8-Bromo-cAMP could inhibit the effects of NPY. Together, Y1R antagonist improved the bone microstructure and reduced bone microdamage in OVX rats. NPY-Y1R could inhibit osteoblast differentiation of BMSCs via cAMP/PKA/CREB pathway. Our findings highlight the regulation of NPY-Y1R in bone metabolism as a potential therapy strategy for the prevention of osteoporosis and osteoporotic fracture.

Safe zone for lateral pin placement for external fixation of the distal humerus.

External fixation is a common, efficient technique used for humeral shaft stabilization and elbow fractures. There are reports of radial nerve injuries associated with this procedure. In this study, we investigated the course and variability of the radial nerve along the lateral humerus in relation to the elbow joint to determine a relatively safe zone for lateral pin placement in external fixation. Twenty upper extremities from 10 cadavers were studied. The nerve branches and course of the radial nerve along the lateral humerus were carefully dissected. Straight lines (a, b, and c) were made connecting three landmarks (the acromion, coracoid process, and anterior wall of the axilla) in the proximal upper extremity to the lateral condyle (LC) of the humerus; their intersections with the radial nerve (A, B, and C) were marked. We analyzed whether the intersection positions were correlated with the connecting line lengths. The mean lengths of the connecting lines were (a) 27.24 ± 2.57, (b) 26.18 ± 2.79, and (c) 20.95 ± 1.44 cm; the distance between the intersection points and the LC of the humerus were (Aa) 7.56 ± 1.31, (Bb) 6.90 ± 2.27, and (Cc) 5.01 ± 0.83 cm; and the measured intersection points of the radial nerve in the lateral aspect of the humerus were (A) 18.48%-34.82%, (B) 13.48%-40.00%, and (C) 19.27%-28.05% of the lengths of lines a, b, and c, respectively. Our data provide a more reliable reference to predict the course of the radial nerve on the lateral humerus and define a safe zone for pin placement. Clin. Anat., 33:637-642, 2020. © 2019 Wiley Periodicals, Inc.

Neuropeptides are associated with pain threshold and bone microstructure in ovariectomized rats.

OBJECTIVES: Postmenopausal osteoporosis (PMO) is a metabolic skeletal disorder with impaired bone density and bone quality in postmenopausal women. The aim of the present study was to investigate the correlation between neuropeptides, bone microstructure and pain threshold in ovariectomized (OVX) rats. METHODS: Female rats were randomly divided into the ovariectomized (OVX) group and the sham surgery (SHAM) group. Bone microstructure and immunocytochemistry for substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY) in tibial and DRG were performed. Pain threshold was assessed at post-operative 11 weeks. Pearson correlation coefficients were calculated between neuropeptides, bone microstructure and pain threshold. RESULTS: Significant decreases in bone volume fraction (BV/TV) and trabecular number (Tb. N) but significant increases in trabecular spacing (Tb.Sp) were showed in OVX group. Mechanical pain threshold (MPT) in OVX group was significantly decreased. The MOD values for SP, CGRP and VIP of tibial in OVX group were significantly lower, whereas NPY, NPY1R and NPY2R were significantly higher. And SP, CGRP, VIP, NPY and NPY2R of DRG were significantly increased in OVX group, while NPY1R was significantly decreased. Correlation analysis showed that NPY, Y1R and Y2R in bone were negatively correlated with BV/TV. MPT was negatively correlated with NPY and Y2R in DRG, and positively correlated with Y1R in DRG. CONCLUSIONS: Our results suggested that SP, CGRP, VIP and NPY were involved in the osteoporotic bone microstructure and mechanical hypersensitivity in OVX rats, indicating the potential to utilize neuropeptides as novel therapeutic targets for PMO.

Neuropeptide Y1 Receptor Antagonist Alters Gut Microbiota and Alleviates the Ovariectomy-Induced Osteoporosis in Rats.

A plethora of evidence has suggested that gut microbiota is involved in the occurrence and development of postmenopausal osteoporosis (PMO). It has been suggested that neuropeptide Y (NPY) modulates the bone metabolism through Y1 receptor (Y1R), and might be associated with gut microbiota. The present study aims to evaluate the anti-osteoporotic effects of Y1R antagonist and to investigate the potential mechanism by which Y1R antagonist regulates gut microbiota. In this study, eighteen female rats were randomly divided into three groups: the sham surgery (SHAM) group, the ovariectomized (OVX) group, and OVX+BIBO3304 group. After 6 weeks following surgery, Y1R antagonist BIBO3304 was administered to the rats in OVX+BIBO3304 group for 7 days. The bone microstructure and serum biochemical parameters were measured at 12 weeks after operation. The differences in the gut microbiota were analyzed by 16S rDNA gene sequencing. Heat-map and Spearman's correlation analyses were constructed to investigate the correlations between microbiota and bone metabolism-related parameters. The results indicated that OVX+BIBO3304 group showed significantly higher BMD, BV/TV, Tb.Th, Tb.N, Conn.D, and serum Ca2+ level than those in OVX group. Additionally, Y1R antagonist changed the gut microbiota composition with lower Firmicutes/Bacteroidetes ratio and higher proportions of some probiotics, including Lactobacillus. The correlation analysis showed that the changes of gut microbiota were closely associated with bone microstructure and serum Ca2+ levels. Our results suggested that Y1R antagonist played an anti-osteoporotic effect and regulated gut microbiota in OVX rats, indicating the potential to utilize Y1R antagonist as a novel treatment for PMO.

MicroRNA-876-5p inhibits cell proliferation, migration and invasion by targeting c-Met in osteosarcoma.

Recently, aberrant expression of miR-876-5p has been reported to participate in the progression of several human cancers. However, the expression and function of miR-876-5p in osteosarcoma (OS) are still unknown. Here, we found that the expression of miR-876-5p was significantly down-regulated in OS tissues compared to para-cancerous tissues. Clinical association analysis indicated that underexpression of miR-876-5p was positively correlated with advanced clinical stage and poor differentiation. More importantly, OS patients with low miR-876-5p level had a significant shorter overall survival compared to miR-876-5p high-expressing patients. In addition, gain- and loss-of-function experiments demonstrated that miR-876-5p restoration suppressed whereas miR-876-5p knockdown promoted cell proliferation, migration and invasion in both U2OS and MG63 cells. In vivo studies revealed that miR-876-5p overexpression inhibited tumour growth of OS in mice. Mechanistically, miR-876-5p reduced c-Met abundance in OS cells and inversely correlated c-Met expression in OS tissues. Herein, c-Met was recognized as a direct target of miR-876-5p using luciferase reporter assay. Notably, c-Met restoration rescued miR-876-5p attenuated the proliferation, migration and invasion of OS cells. In conclusion, these findings indicate that miR-876-5p may be used as a potential therapeutic target and promising biomarker for the diagnosis and prognosis of OS.

Interleukin-34 Synovial Fluid Was Associated with Knee Osteoarthritis Severity: A Cross-Sectional Study in Knee Osteoarthritis Patients in Different Radiographic Stages.

BACKGROUND: Inflammation might play a crucial role in the pathogenesis of osteoarthritis (OA). Interleukin-34 (IL-34) is a well-known proinflammatory cytokine. OBJECTIVE: The objective of this study was to detect IL-34 levels in serum and synovial fluid (SF) of patients with OA and to investigate their correlation with radiographic and symptomatic severity. METHODS: One hundred and eighty-two OA patients and 69 controls were recruited. IL-34 levels were measured by enzyme-linked immunosorbent assay (ELISA). Radiographic and symptomatic severity of OA was reflected by Kellgren-Lawrence (KL) grades and Western Ontario McMaster University Osteoarthritis Index (WOMAC) scores, respectively. RESULTS: SF IL-34 levels were independently associated with the KL grade (B = 0.273, 95% CI: 0.150-0.395; P < 0.001). SF IL-34 levels were significantly correlated with WOMAC scores (r = 0.265, 95% CI: 0.123-0.399; P < 0.001). The correlation between SF IL-34 levels and WOMAC scores was still significant after adjusting for confounding factors (B = 0.020, 95% CI: 0.001-0.038; P = 0.035) in OA patients. CONCLUSIONS: We found that IL-34 levels in SF were significantly associated with the radiographic and symptomatic severity of knee OA.

Feasibility and Safety of a Cemented PEEK-on-PE Knee Replacement in a Goat Model: A Preliminary Study.

Polyether-ether-ketone (PEEK) is a potential alternative to metal alloys for use in the orthopedic implants; however, an in vivo study in an appropriate animal model is essential and has not yet been initiated. The aim of the present study was to gather some preliminary evidence regarding the performance and safety of a cemented PEEK-based knee replacement device in a goat model. Fifteen adult goats were randomly divided into two groups; the control group (n = 5), which received a sham operation, and the experimental group (n = 10), which received a total knee arthroplasty with a PEEK-based knee replacement device. The animals were sacrificed at 12 (control n = 5; experimental n = 5) or 24 weeks (experimental n = 5). Blood parameter measurements and radiographs of the knee joints were obtained. The synovium and main organs were removed and histologically assessed. The knee joints with the prosthesis were analyzed via micro-computed tomography and laser confocal microscopy. There was no occurrence of implant fracture or prosthesis sinking during the 24 weeks of radiological observations, except for one case of prosthesis dislocation at 4 weeks. There was a 6% decrease in femoral bone density (BD) at 12 weeks, but no further decrease by 24 weeks. No changes in BD were observed in the tibial ends. The bulk implant was biocompatible in terms of histological analysis of the local synovium and organs. There were no optical scratches on the surface of the retrieved components; the femoral component surface was rougher, while the tibial insert was smoother after 24 weeks. The novel PEEK-based knee replacement device in a goat model was feasible and safe; however, prior to use in humans, further studies concerning PEEK high load-bearing implant designs should be carried out to expand on our results.

Naringin protects against steroid­induced avascular necrosis of the femoral head through upregulation of PPARγ and activation of the Notch signaling pathway.

Naringin, a flavonoid, is the effective pharmaceutical ingredient of drynaria, with the effects of healing fractures, strengthening bones and promoting kidney function. The aim of the present study was to investigate the potential effect of naringin on steroid­induced avascular necrosis of the femoral head (SANFH). Treatment with naringin markedly protected against the steroid­induced decrease in serum osteocalcin levels, and the rate of osteonecrosis in a model of SANFH. In addition, naringin decreased the total cholesterol and low density lipoprotein/high density lipoprotein ratio in the SANFH rabbit. It was observed that naringin markedly inhibited caspase­3 activity, increased runt­related transcription factor 2 and transcription factor sp7 mRNA expression, promoted alkaline phosphatase activity and upregulated collagen I, peroxisome proliferator­activated receptor (PPAR) Î³2, neurogenic locus notch homolog protein (Notch), ß­catenin and phosphorylated­Rac­α serine/threonine protein kinase protein expression in the SANFH rabbit. The results of the present study demonstrated that naringin protects against SANFH through upregulation of PPARγ2 and activation of the Notch signaling pathway, and may be a useful addition to the treatment options for diseases of the femoral head.

Naringin inhibits vascular endothelial cell apoptosis via endoplasmic reticulum stress­ and mitochondrial­mediated pathways and promotes intraosseous angiogenesis in ovariectomized rats.

In this study, to investigate the effects of naringin on vascular endothelial cell (VEC) function, proliferation, apoptosis, and angiogenesis, rat VECs were cultured in vitro and randomly divided into four groups: control, serum­starved, low­concentration naringin treatment, and high­concentration naringin treatment. MTT assay was used to detect cell proliferation while Hoechst 33258 staining and flow cytometry were used to detect apoptosis. Changes in the expression of apoptosis­associated proteins [GRP78, CHOP, caspase­12, and cytochrome c (Cyt.c)] were detected using western blotting. JC­1 staining was employed to detect changes in mitochondrial membrane potential. Intracellular caspase­3, ­8, and ­9 activity was determined by spectrophotometry. ELISA was used to detect endothelin (ET), and a Griess assay was used to detect changes in the expression of nitric oxide (NO) in culture medium. The study further divided an ovariectomized (OVX) rat model of osteoporosis randomly into four groups: OVX, sham­operated, low­concentration naringin treatment (100 mg/kg), and high­concentration naringin treatment (200 mg/kg). After 3 months of treatment, changes in serum ET and NO expression, bone mineral density (BMD), and microvessel density of the distal femur (using CD34 labeling of VECs) were determined. At each concentration, naringin promoted VEC proliferation in a time­ and dose­dependent manner. Naringin also significantly reduced serum starvation­induced apoptosis in endothelial cells, inhibited the expression of GRP78, CHOP, caspase­12, and Cyt.c proteins, and reduced mitochondrial membrane potential as well as reduced the activities of caspase­3 and ­9. Furthermore, naringin suppressed ET in vitro and in vivo while enhancing NO synthesis. Distal femoral microvascular density assessment showed that the naringin treatment groups had a significantly higher number of microvessels than the OVX group, and that microvascular density was positively correlated with BMD. In summary, naringin inhibits apoptosis in VECs by blocking the endoplasmic reticulum (ER) stress­ and mitochondrial­mediated pathways. Naringin also regulates endothelial cell function and promotes angiogenesis to exert its anti­osteoporotic effect.

[Role of substance P and calcitonin gene-related peptide in bone metabolism].

Substance P (SP) and calcitonin gene-related peptide (CGRP) are the neuropeptides released from the sensory nerve endings. Neuropeptides play a role in bone and the relevant organs. It exerts functions in regulation of the bone metabolism, fracture healing and pain by a certain way. The biological properties and distributions of SP and CGRP are closely related to the pathogenesis and development of bone metabolism, fracture healing and pain.