Nrf2 signaling activation by a small molecule activator compound 16 inhibits hydrogen peroxide-induced oxidative injury and death in osteoblasts.

We explored the potential activity of compound 16 (Cpd16), a novel small molecule Nrf2 activator, in hydrogen peroxide (H2O2)-stimulated osteoblasts. In the primary murine/human osteoblasts and MC3T3-E1 murine osteoblastic cells, Cpd16 treatment at micro-molar concentrations caused disassociation of Keap1-Nrf2 and Nrf2 cascade activation. Cpd16 induced stabilization of Nrf2 protein and its nuclear translocation, thereby increasing the antioxidant response elements (ARE) reporter activity and Nrf2 response genes transcription in murine and human osteoblasts. Significantly, Cpd16 mitigated oxidative injury in H2O2-stimulited osteoblasts. H2O2-provoked apoptosis as well as programmed necrosis in osteoblasts were significantly alleviated by the novel Nrf2 activator. Cpd16-induced Nrf2 activation and osteoblasts protection were stronger than other known Nrf2 activators. Dexamethasone- and nicotine-caused oxidative stress and death in osteoblasts were attenuated by Cpd16 as well. Cpd16-induced osteoblast cytoprotection was abolished by Nrf2 short hairpin RNA or knockout, but was mimicked by Keap1 knockout. Keap1 Cys151S mutation abolished Cpd16-induced Nrf2 cascade activation and osteoblasts protection against H2O2. Importantly, weekly Cpd16 administration largely ameliorated trabecular bone loss in ovariectomy mice. Together, Cpd16 alleviates H2O2-induced oxidative stress and death in osteoblasts by activating Nrf2 cascade.

A novel Keap1 inhibitor iKeap1 activates Nrf2 signaling and ameliorates hydrogen peroxide-induced oxidative injury and apoptosis in osteoblasts.

An ultra-large structure-based virtual screening has discovered iKeap1 as a direct Keap1 inhibitor that can efficiently activate Nrf2 signaling. We here tested its potential effect against hydrogen peroxide (H2O2)-induced oxidative injury in osteoblasts. In primary murine and human osteoblasts, iKeap1 robustly activated Nrf2 signaling at micromole concentrations. iKeap1 disrupted Keap1-Nrf2 association, causing Nrf2 protein stabilization, cytosol accumulation and nuclear translocation in murine and human osteoblasts. The anti-oxidant response elements (ARE) activity and transcription of Nrf2-ARE-dependent genes (including HO1, NQO1 and GCLC) were increased as well. Significantly, iKeap1 pretreatment largely ameliorated H2O2-induced reactive oxygen species production, lipid peroxidation and DNA damage as well as cell apoptosis and programmed necrosis in osteoblasts. Moreover, dexamethasone- and nicotine-induced oxidative injury and apoptosis were alleviated by iKeap1. Importantly, Nrf2 shRNA or CRISPR/Cas9-induced Nrf2 knockout completely abolished iKeap1-induced osteoblast cytoprotection against H2O2. Conversely, CRISPR/Cas9-induced Keap1 knockout induced Nrf2 cascade activation and mimicked iKeap1-induced cytoprotective actions in murine osteoblasts. iKeap1 was ineffective against H2O2 in the Keap1-knockout murine osteoblasts. Collectively, iKeap1 activated Nrf2 signaling cascade to inhibit H2O2-induced oxidative injury and death of osteoblasts.

[Retrospective and comparative analysis of therapy for degenerative chronic discogenic low back pain with end plate Modic changes with discography and intradiscal injection blockage].

OBJECTIVE: To evaluate the prognosticating effects of discography and intradiscal injection blockage for patients with degenerative chronic discogenic low back pain and end plate Modic changes when posterior lumbar interbody fusion (PLIF) was adopted. METHODS: Patients who received diagnostic discography for suspected degenerative discogenic low back pain were recruited. A total of 60 patients (42 males and 18 females) with positive discography and end plate Modic changes at a single level were enrolled in the study and allocated into Groups A and B: Group A was both positive sign of discography and negative sign of intradiscal injection blockage two weeks later, which further was subdivided into Group A1 (Modic I endplate change) and Group A2 (Modic II endplate change). Group B was both positive sign of discography and intradiscal injection blockage two weeks later, which further was subdivided into Group A1 (Modic I endplate change) and Group A2 (Modic II endplate change). There were 15 cases in each subgroup, with a mean age of 43.2 years old (29 to 62 years old). The lumbar decompression combined with interbody fusion was performed for these patients. The clinical outcome of each patient was evaluated and recorded by using the VAS and ODI before operation and at 24 months after the procedure. The bone fusion state was evaluated by both dynamic X-ray and CT reconstruction films. RESULTS: There was no statistical difference of the scales of VAS and ODI before operation.Compared with the scales before operation, although the scales of VAS and ODI of both group A and group B at 24 months after the procedure were significantly improved, the scales of both VAS and ODI of group B were significantly superior to group A. The statistics analysis showed that comparing the improvement rate of VAS and ODI before and after operation, group B was significantly superior to group A, but there was no obviously correlations between the type of Modic endplate change and the the improvement rate of VAS and ODI. CONCLUSION: The combination the discography with intradiscal injection blockage before operation would effectively prognosticate the therapy of posterior lumbar interbody fusion. There was no obviously correlations between the type of Modic endplate change and the improvement rate of VAS and ODI.

[A model of acute compression spinal cord injury by a mini-invasive expandable balloon in goats].

OBJECTIVE: To establish a reproducible and manipulable model of acute spinal cord compression injury in large mammals so as to provide a technical and experimental platform for the repair and reconstruction of spinal cord injury (SCI). METHODS: A total of 15 adult male goats, weighting 35 - 45 kg, were selected. After intravenous anesthesia, a model of acute spinal cord compression injury was established with the balloon of kyphoplasty through mini-open laminotomy. The animals were divided into 4 groups, i.e. 3 in group A and 4 each in groups B, C and D. Goats in group A received mini-open laminotomy without insertion of balloon. In group B, balloons were surgically positioned within the T10-T11 spinal canal but not inflated. The spinal cords of goats in group C were partially compressed by inflating the balloon to approximately 30% of anterior/posterior diameter of vertebral canal. In group D, the balloon was inflated to occupy approximately 90% of canal on a lateral view. X-ray and thin-section computed tomography (CT) scans were used to determine the balloon location. CT scans were also used to calculate the magnitude of balloon inflation and the degree of spinal cord compression within vertebral canal. Improved Tarlov motor function grade test and somatosensory evoked potentials (SSEP) were employed to evaluate the goat neurofunction 24 hours before and 7 days after surgery. RESULTS: Dye volumes of 0, 1.26 ± 0.18 and 2.82 ± 0.20 ml were injected into the balloon to produce spinal occupancies of 0%, 33% ± 2% and 89% ± 4% on X-ray and CT scan. There was a significant dose response for the different levels of injury, with reduced conduction of somatosensory evoked potentials and impaired mobility 7 days after injury. CONCLUSION: A model of acute spinal cord injury by a tunable compression with a mini-invasive balloon in goats is a useful experiment model of spinal cord injury. It may simulate the clinical situations of acute SCI.

[The evaluation of posterior ligament complex injury as well as the analysis of its effects in thoracic-lumbar fractures].

OBJECTIVES: To evaluate and analyze the role of posterior ligament complex (PLC) in determining therapeutic principle for traumatic thoracic-lumbar fracture. METHODS: From August 2005 to May 2008, 60 patients (38 male, 22 female) who suffered from the traumatic thoracic-lumbar fracture were carried out posterior operations. According to the Magerl traumatic thoracic-lumbar fracture classification system, these cases were classified to subtype A, B and C. The average age was 34 years (21 - 65 years). Magnetic resonance imaging (MRI) scan, which including both T1/T2 weight and fat-stir sequence, as well as the MRI negative film reading technique were used to evaluate the state of PLC. Furthermore, related physical or neurological examinations (such as severe skin bruising and sinking, broadening spinous process gap and tenderness, spinal cord or nerve root injury) and another X-ray or CT reconstruction films were taken to evaluate the the state of PLC synthetically. Above-mentioned results were compared with the final exploration results during operation and some parameters were analyzed. RESULTS: The sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), misdiagnosis rate and rate of missed diagnosis of these sixty patients were 85.3%, 80.8%, 83.3%, 85.3%, 80.8%, 19.2%, 14.7% respectively. After 13 cases of thoracic-lumbar fracture-dislocation were eliminated, the sensitivity, specificity, accuracy, PPV, NPV, misdiagnosis rate and rate of missed diagnosis of remaining 47 cases were 81.0%, 80.8%, 80.9%, 77.3%, 84.0%, 19.2%, 19.0% respectively. There were 5 cases with MRI negative results before operation but positive results during operation. Contrarily, 5 cases with MRI positive results before operation but negative results during operation occurred. CONCLUSIONS: MRI is a main means for evaluating the state of PLC. Although the MRI fat-stir sequence as well as the MRI negative film reading technique are adopted, the state of PLC can not be estimated exactly before operation (especially for those unfracture dislocation cases). In order to estimate the state of PLC exactly, the related local physical examination and image technology as well as the location of the abnormal image signal in MRI film and time of injury must be analyzed synthetically.

[Utility of nickel-titanium shape memory alloys of vertebral body reduction fixator with assisted distraction bar].

OBJECTIVE: To test the nickel-titanium (Ni-Ti) shape memory alloys of vertebral body reduction fixator with assisted distraction bar for the treatment of traumatic and osteoporotic vertebral body fracture. METHODS: A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar was implanted into the compressed fracture specimens through vertebral pedicle with the radiographic monitoring to reduce the collapsed endplate as well as distract the compressed vertebral fracture. Radiographic film and computed tomographic reconstruction technique were employed to evaluate the effects of reduction and distraction. A biomechanic test machine was used to measure the fatigue and the stability of deformation of fixation segments. RESULTS: Relying on the effect of temperature shape memory, such an assembly could basically reduce the collapsed endplate as well as distract the compressed vertebral fracture. And when unsatisfied results of reduction and distraction occurred, its super flexibility could provide additional distraction strength. CONCLUSION: A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar may provide effective endplate reduction, restore the vertebral height and the immediate biomechanic spinal stability. So the above assembly is indicated for the treatment of traumatic and osteoporotic vertebral body fracture.