Selective removal of misfolded SOD1 delays disease onset in a mouse model of amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease. There is no cure currently. The discovery that mutations in the gene SOD1 are a cause of ALS marks a breakthrough in the search for effective treatments for ALS. SOD1 is an antioxidant that is highly expressed in motor neurons. Human SOD1 is prone to aberrant modifications. Familial ALS-linked SOD1 variants are particularly susceptible to aberrant modifications. Once modified, SOD1 undergoes conformational changes and becomes misfolded. This study aims to determine the effect of selective removal of misfolded SOD1 on the pathogenesis of ALS. METHODS: Based on the chaperone-mediated protein degradation pathway, we designed a fusion peptide named CT4 and tested its efficiency in knocking down intracellularly misfolded SOD1 and its efficacy in modifying the pathogenesis of ALS. RESULTS: Expression of the plasmid carrying the CT4 sequence in human HEK cells resulted in robust removal of misfolded SOD1 induced by serum deprivation. Co-transfection of the CT4 and the G93A-hSOD1 plasmids at various ratios demonstrated a dose-dependent knockdown efficiency on G93A-hSOD1, which could be further increased when misfolding of SOD1 was enhanced by serum deprivation. Application of the full-length CT4 peptide to primary cultures of neurons expressing the G93A variant of human SOD1 revealed a time course of the degradation of misfolded SOD1; misfolded SOD1 started to decrease by 2 h after the application of CT4 and disappeared by 7 h. Intravenous administration of the CT4 peptide at 10 mg/kg to the G93A-hSOD1 reduced human SOD1 in spinal cord tissue by 68% in 24 h and 54% in 48 h in presymptomatic ALS mice. Intraperitoneal administration of the CT4 peptide starting from 60 days of age significantly delayed the onset of ALS and prolonged the lifespan of the G93A-hSOD1 mice. CONCLUSIONS: The CT4 peptide directs the degradation of misfolded SOD1 in high efficiency and specificity. Selective removal of misfolded SOD1 significantly delays the onset of ALS, demonstrating that misfolded SOD1 is the toxic form of SOD1 that causes motor neuron death. The study proves that selective removal of misfolded SOD1 is a promising treatment for ALS.

Ipsilateral Fixation and Reconstruction of the Cervical Spine after Resection of a Dumbbell Tumor Via a Unilateral Posterior Approach: A Case Report and Biomechanical Study.

OBJECTIVE: There is lack of an internal fixation following resection of a dumbbell tumor by hemi-laminectomy and facetectomy that achieves adequate stability with less trauma. Unilateral fixation and reconstruction (unilateral pedicle screw and contralateral lamina screw fixation combined with lateral mass reconstruction, UPS + CLS + LM) may be an ideal technique to address this problem. A biomechanical comparison and a case report were designed to evaluate its spinal stability and clinical effect. METHODS: Seven fresh-frozen human subcervical specimens were used for the biomechanical testing. The conditions tested were: (1) intact; (2) injured (single-level hemi-laminectomy and facetectomy); (3) unilateral pedicle screw (UPS) fixation; (4) UPS fixation combined with lateral mass (LM) reconstruction (UPS + LM); (5) UPS fixation and contralateral lamina screw fixation (UPS + CLS); (6) UPS + CLS + LM; (7) UPS fixation and contralateral transarticular screw fixation (UPS + CTAS); (8) bilateral pedicle screw (BPS) fixation. Range of motion (ROM) and neutral zone (NZ) were obtained at C5-C7 segment under eight conditions. In addition, we report the case of a patient with a C7-T1 dumbbell tumor that was treated by UPS + CLS + LM technique. RESULTS: Except left/right lateral bending and right axial rotation (all, p < 0.05), ROM of UPS + CLS + LM condition in other directions was similar to that of BPS condition (all, p > 0.05). There was no significant difference between UPS + CLS + LM and the UPS + CTAS condition in other directions of ROM (all, p > 0.05), except in left/right axial rotation (both, p < 0.05). Compared to UPS + CLS condition, left/right lateral bending ROM of UPS + CLS + LM condition were significantly reduced (both, p < 0.05). UPS + CLS + LM condition significantly reduced ROM in all directions compared to UPS and UPS + LM condition (all, p < 0.05). Similarly, except lateral bending (p < 0.05), there was no difference in NZ in other directions between UPS + CLS + LM and BPS condition (both, p > 0.05). There was no significant difference between UPS + CLS + LM and UPS + CTAS condition in NZ in all directions (all, p > 0.05). Axial rotation NZ of UPS + CLS + LM condition was significantly reduced compared to UPS + CLS condition (p < 0.05). Compared to UPS and UPS + LM condition, NZ of UPS + CLS + LM condition was significantly reduced in all directions (all, p < 0.05). The patient's imaging examination at 3 months postoperatively indicated that the internal fixation did not move and the graft bone was seen with fusion. CONCLUSION: After resection of a dumbbell tumor in the cervical spine, UPS + CLS + LM technique is a reliable internal fixation method to provide sufficient immediate stability and promote postoperative bone fusion.

Posterior unilateral exposure and stability reconstruction with pedicle and lamina screw fixation for the cervical dumbbell tumorectomy: a case report and biomechanical study.

PURPOSE: Cervical dumbbell tumor is usually removed via a posterior approach and may require the spinal fixation sometimes. However, the present surgical methods involved either more trauma or a higher risk of instability of the cervical spine. A new technique of unilateral exposure and stability reconstruction with pedicle and lamina screws fixation for posterior cervical dumbbell tumorectomy was described and compared with conventional techniques. METHODS: Posterior unilateral exposure, hemi-laminectomy and facetectomy were performed in one patient with the cervical dumbbell tumor between C3 and C4. The stability was reconstructed by the unilateral pedicle and lamina screws fixation (UPLS), and a strip of shaped allograft bone was also implanted between the superior and inferior lateral mass. Biomechanical stability test of this new technique was investigated using seven fresh-frozen human cervical spine specimens (C4-C7) and compared with unilateral pedicle screw (UPS) and bilateral pedicle screw fixation (BPS) techniques. A continuous pure moment of ± 2.0 Nm was applied to the specimen in flexion, extension, lateral bending and axial rotation. RESULTS: The cervical dumbbell tumor was removed completely, and bone fusion with continuous bone trabecula was maintained in the patient on the final follow-up examination at 18 months postoperatively. Biomechanical stability tests revealed that the range of motion of the UPLS fixation plus graft bone implant was the same as the BPS fixation in flexion (1.8°vs. 1.5°, p = 0.58) and extension (2.3°vs. 2.2°, p = 0.73), but significantly bigger in lateral bending (3.9° vs. 1.0°, p < 0.001) and axial rotation (6.8° vs. 3.8°, p = 0.002), which were significantly smaller than the UPS fixation in all directions (all p < 0.001). CONCLUSIONS: For the treatment of cervical dumbbell tumor, posterior unilateral exposure and stability reconstruction with pedicle and lamina screws fixation following hemi-laminectomy and facetectomy appear to be a more stable and lesser trauma technique. LEVEL OF EVIDENCE: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Percutaneous Vertebroplasty and Facet Blocking for Treating Back Pain Caused by Osteoporotic Vertebral Compression Fracture.

Methods: Clinical and radiological data of 204 patients were reviewed. The patients were divided into Group A (PVP alone) and Group B (PVP and FB combined therapy) according to treatments. Back pain was evaluated with Visual Analog Scale (VAS) and Oswestry Disability Index (ODI). The operation, fluoroscopic exposure time, and bone cement leakage were recorded. The χ 2 test, Student's t-test, and repeated measures analysis of variance were used to compare the differences between the two groups. Results: There were 125 patients in Group A and 79 patients in Group B. Their baseline characteristics were similar (P > 0.05). The mean VAS scores of Group A and Group B were 7.03 and 7.21 at admission, 4.7 and 3.2 at 1 day after operation, 4.0 and 3.0 at 3 months, and 2.2 and 2.2 at 12 months after operation, respectively. The mean ODI scores of Group A and Group B were 30.9 and 29.8 at admission, 17.6 and 17.7 at 3 months, and 10.5 and 10.9 at 12 months after operation, respectively. The mean operation time and fluoroscopic exposure time of Group A (35.6 minutes and 7.2 seconds, respectively) was significantly shorter than that of Group B (45.7 minutes and 11.7 seconds, respectively, P < 0.01). The incidence of bone cement leakage and new fractures after operation did not have statistically significant difference between groups. Conclusion: PVP and FB combined therapy could provide better pain relief than PVP alone in short term after operation in patients with OVCFs associated back pains.

Epidural angiolipoma with concomitant intradural extramedullary capillary hemangioma at the same spinal level: A case report.

Spinal epidural angiolipomas (SALs) and spinal intradural extramedullary capillary hemangiomas (SIECHs) are both types of rare benign tumor, and their pathogeneses appear to be associated. The present report is, to the best of our knowledge, the first case of spinal angiolipoma and intradural extramedullary capillary hemangioma occurring at the same spinal level. A 54 year-old male patient experienced two operations within four months due to the occurrence of SAL and one SIECH at the T3 level presenting with sudden paraplegia. Although the co-occurrence of SAL and SIECH at the same spinal level is an extremely rare condition, omitting the intradural tumor may be averted via scrutiny of preoperative images.

A Cervical Spinal Cord Hemi-Contusion Injury Model Based on Displacement Control in Non-Human Primates (Macaca fascicularis).

Non-human primate (NHP) spinal cord injury (SCI) models can be informative in the evaluation of treatments that show promise in rodent models prior to translation to humans. In the present study, we aimed to establish a cervical spinal hemi-contusion model with controlled displacement and evaluate the abnormalities in behavior, electrophysiology, histology, and magnetic resonance imaging. Twelve adult NHPs were divided into an SCI group (n = 8, 24 and 48 weeks) and a control group (n = 4). An impactor (Φ = 4 mm) was driven to compress the left C5 cord at 800 mm/sec. The contusion displacement and peak force was 4.08 ± 0.17 mm and 19.8 ± 4.6 N. The behavioral assessment showed a consistent dysfunction below the wrist and spontaneous recovery of limb function after injury. Lesion length and lesion area at the epicenter based on T2 hyperintensity were 5.68 ± 0.47 mm and 5.99 ± 0.24 mm2 at 24 weeks post-injury (wpi), and 5.29 ± 0.17 mm and 5.95 ± 0.24 mm2 at 48 wpi. The spared spinal cord area immuno-positive for glial fibrillary acidic protein was significantly reduced, while the staining intensity increased at 24 wpi and 48 wpi, compared with the sham group. Ipsilateral somatosensory and motor evoked potentials were dynamic, increasing in latency and decreasing in amplitude compared with pre-operative values or the contralateral values, and correlated to varying degrees with behavioral outcomes. A shift in size-frequency distribution of sensory neurons of the dorsal root ganglia (DRG) was consistent with a loss of large-diameter cells. The present study demonstrated that the NHP SCI model resulted in consistent unilateral limb dysfunction and potential plasticity in the face of loss of spinal cord and DRG tissue.

Pedicle screw loosening: the value of radiological imagings and the identification of risk factors assessed by extraction torque during screw removal surgery.

BACKGROUND CONTEXT: Pedicle screw loosening is a common complication after spine surgeries. Traditionally, it was assessed by radiological approaches, both X-ray and CT (computed tomography) scan, while reports using mechanical method to study screw loosening after spine surgery are rare. The primary objective was to study the prevalent of pedicle screw loosening according to extraction torque during screw removal surgery and access the sensitivity and specificity of both X-ray and CT scan for diagnosing screw loosening. The second objective was to identify the risk factors for low extraction torque of pedicle screw that might lead to loosening. METHODS: Thirty-three patients who underwent pedicle screw removal surgery after at least 2 years from primary surgery were evaluated preoperatively for fixation stability by X-ray and CT scan. In total, 236 screws were taken out, and the extraction torque data was recorded and analyzed to identify the sensitivity and specificity of both imaging studies for screw loosening. Furthermore, risk factors that might contribute to low extraction torque were also studied. RESULTS: The mean extraction torque of removed screws was 1.55 ± 1.00 Nm; a torque force of less than 1.02 Nm was used to define a screw as loosened. According to such criterion, the loosening rate was found to be 33%. X-ray had a sensitivity of 24% and a specificity of 98%, while CT scan had a sensitivity of 22% and a specificity of 96%. Extraction torque of pedicle screws inserted in fractured vertebrae was significantly lower than those in non-fractured vertebrae (p = 0.009); meanwhile, screws of non-fusion surgery had lower extraction torque when compared to those in fusion surgery (p = 0.001). BMD (bone mineral density) and age had low but significant linear relationship with screw extraction torque (p = 0.01, R2 = 0.304; p = 0.045, R2 = 0.123). CONCLUSIONS: Our findings showed that both X-ray and CT scan had high specificity for screw loosening detection, but their sensitivities were relatively low. Surgeons needed to be more cautious when assessing screw loosening merely according to radiological examination, and aware of that screws in fractured vertebrae or non-fusion surgery were vulnerable to loosening.