Ying-Zhao Yan

Sirt6 overexpression suppresses senescence and apoptosis of nucleus pulposus cells by inducing autophagy in a model of intervertebral disc degeneration

Treatment of intervertebral disc degeneration (IDD) seeks to prevent senescence and death of nucleus pulposus (NP) cells. Previous studies have shown that sirt6 exerts potent anti-senescent and anti-apoptotic effects in models of age-related degenerative disease. However, it is not known whether sirt6 protects against IDD. Here, we explored whether sirt6 influenced IDD. The sirt6 level was reduced in senescent human NP cells. Sirt6 overexpression protected against apoptosis and both replicative and stress-induced premature senescence. Sirt6 also activated NP cell autophagy both in vivo and in vitro. 3-methyladenine (3-MA) and chloroquine (CQ)-mediated inhibition of autophagy partially reversed the anti-senescent and anti-apoptotic effects of sirt6, which regulated the expression of degeneration-associated proteins. In vivo, sirt6 overexpression attenuated IDD. Together, the data showed that sirt6 attenuated cell senescence, and reduced apoptosis, by triggering autophagy that ultimately ameliorated IDD. Thus, sirt6 may be a novel therapeutic target for IDD treatment.

Panax quinquefolium saponin inhibits endoplasmic reticulum stress-induced apoptosis and the associated inflammatory response in chondrocytes and attenuates the progression of osteoarthritis in rat

Treatments for osteoarthritis (OA) seek to restore chondrocyte function and inhibit cell apoptosis. Panax quinquefolium saponin (PQS) is the major active ingredient of Radix panacis quinquefolii (American ginseng), and has been demonstrated to exert anti-inflammatory and anti-apoptotic effects in various diseases. However, any potential effect of PQS on the pathological process of OA remains unclear. This work aimed to explore the role of PQS in chondrocytes and to clarify its potential mechanisms. We showed that PQS treatment could protect chondrocytes against endoplasmic reticulum (ER) stress and associated apoptosis induced by interleukin (IL)-1β. Also, PQS further attenuated triglyceride (TG)-induced ER stress and associated apoptosis. Moreover, PQS may inhibit the ER stress-activated NF-κB pathway and associated inflammatory response in chondrocytes. Finally, PQS abolished rat cartilage degeneration in an in-vivo OA model of the knee joint. Our results indicate that PQS may be a potential novel treatment for OA.

Gastrodin reduces IL-1β-induced apoptosis, inflammation, and matrix catabolism in osteoarthritis chondrocytes and attenuates rat cartilage degeneration in vivo

Therapeutics for osteoarthritis (OA) are intended to restore chondrocyte function and inhibit cell apoptosis. Previous studies have shown that gastrodin had anti-apoptotic and anti- inflammatory effects. However, little is known about whether gastrodin has protective effects against the processes of OA. We studied the potential effects of gastrodin on chondrocytes and the underlying mechanisms. Our results showed that gastrodin could prevent chondrocyte apoptosis induced by IL-1β. Additionally, gastrodin suppressed the nuclear factor kappa B (NF-κB) pathway, decreased the release of inflammatory mediators (IL-6, TNF-α), and reduced matrix catabolism in IL-1β-treated chondrocytes. Furthermore, gastrodin ameliorated rat cartilage degeneration in an OA model of knee joints in vivo, suggesting its potential as a candidate therapeutic for OA.

Biomechanical Role of the Thoracolumbar Ligaments of the Posterior Ligamentous Complex: A Finite Element Study

OBJECTIVESnTo investigate the effect of sequential ligament failure on the range of motion (ROM) and location of the instantaneous axes of rotation (IAR) of the thoracolumbar spine (T12-L1) finite element (FE) model, and to verify the role of the supraspinous ligament (SSL) in maintaining the stability of the injured thoracolumbar spine.nnnMETHODSnAn FE model of the fractured thoracolumbar spine was developed and validated against published data. The posterior ligamentous complex (PLC) in the fractured T12-L1 segment was then reduced in a sequential manner from the facet capsular ligament (FCL), part of the interspinous ligament (ISL), SSL, and entire ISL, to the ligamentum flavum (LF). The ROM and IAR of the T12-L1 segment were measured at the fracture and at each reduced ligament step under 4 directions of flexion, extension, lateral bending, and rotation, and 4 bending motions of 1.5, 3.0, 4.5, 6.0 Nm.nnnRESULTSnThe FE model showed a consistent increase in the ROM and location of the IAR as the ligaments were removed sequentially. Furthermore, failure of the SSL had the most significant influence on the change in the ROM and IAR in flexion. In extension, removal of the FCL caused the largest shift.nnnCONCLUSIONSnThe SSL is a significant ligament that allows the PLC to maintain the stability of the thoracolumbar spine during injury.

Rate of presence of 11 thoracic vertebrae and 6 lumbar vertebrae in asymptomatic Chinese adult volunteers

BackgroundAn increasing number of studies on spinal morphology in asymptomatic Asian and Western patients have been reported. Variation in spinal anatomy among patients is considered as the cause of wrong-level surgery in up to 40% of cases. The present study examined the rate of presence of 11 thoracic vertebrae and 6 lumbar vertebrae in 293 asymptomatic Chinese adult volunteers.MethodsFrom May 27, 2016, to November 11, 2017, a cohort of 325 asymptomatic Chinese adults meeting the study exclusion criteria was recruited. The radiographs were examined by a spine surgeon and a radiologist to assess the number of thoracic and lumbar vertebrae.ResultsIn total, 293 volunteers were included in this study: 17 (5.8%) had 11 thoracic vertebrae, and 16 (5.5%) had 6 lumbar vertebrae. Among all volunteers, 12 (4.1%) had 7 cervical vertebrae (C), 11 thoracic vertebrae (T), and 5 lumbar vertebrae (L); 5 (1.7%) had 7C, 11T, and 6L; and 11 (3.8%) had 7C, 12T, and 6L. There was no difference between the findings of the spine surgeon and the radiologist.ConclusionsFor the first time, this study describes the rate of presence of 11 thoracic vertebrae and 6 lumbar vertebrae in 293 asymptomatic Chinese adult volunteers. Variations in the number of thoracic and lumbar vertebrae tend to be ignored by spine surgeons. We encourage spinal surgeons and researchers to be aware of such variations when performing thoracic- and lumbar-level surgery and assessing spinal alignment and parameters.

Acceptable Chin–Brow Vertical Angle for Neutral Position Radiography: Preliminary Analyses Based on Parameters of the Whole Sagittal Spine of an Asymptomatic Chinese Population

OBJECTIVEnWe sought to acquire the whole sagittal spine parameters and investigated the acceptable chin-brow vertical angle (CBVA) for neutral position radiography in an asymptomatic Chinese population.nnnMETHODSnThe parameters measured in 257 asymptomatic volunteers included CBVA, occipital slope, orbital tilt, occipital incidence, C0-C2 Cobb angle, C2-C7 Cobb angle, C1-C7 Cobb angle, C2-C7 sagittal vertical axis and absolute rotation angle, cervical tilt, cranial tilt, T1 slope, and thoracic kyphosis, and others. We used Pearson correlation analyses to find relationships between CBVA and other variables. The subjects were divided into 5 groups according to the CBVA percentile: group A, 0%-20% CBVA; group B, 20%-40% CBVA; group C, 40%-60% CBVA; group D, 60%-80% CBVA; and group E, 80%-100% CBVA. We used analysis of variance to analyze differences among the 5 groups.nnnRESULTSnOrbital tilt, Occipital incidence, C1-C7 Cobb angle, C2-C7 sagittal vertical axis, and cranial tilt all increased with increasing CBVA (P < 0.001). The occipital slope, C2-C7 Cobb angle, C2-C7 absolute rotation angle, cervical tilt, T1 slope, and thoracic kyphosis decreased with decreasing CBVA (P < 0.05). No correlations between other sagittal parameters and the CBVA were found. A slight deviation was found in groups B-D, with a greater deviation in groups A, C, and E.nnnCONCLUSIONSnAn acceptable range ofxa0-1.5° to 5.8° is recommended for the CBVA for cervical radiography in the neutral position. When spinal surgeons evaluate the cervical plane, the effects of the CBVA deviation on cervical curvature must be considered.

Does the Iliac Wing Influence L5 Pedicle Screw Fixation

OBJECTIVEnTo explore whether the iliac wing influences L5 pedicle screw (PS) fixation and to propose methods to reduce such influence.nnnMETHODSnA total of 100 computed tomography scans (from 50 male and 50 female patients) of the lower lumbar region and pelvis were obtained and 3-dimensionally reconstructed. Cylinders with 6.5-mm diameters were drawn to simulate the different trajectories of L5 PS. The maximum lengths and lateral angles of trajectories, and the vertical distances from the inner edge of the iliac wing to these trajectories, were measured.nnnRESULTSnThe maximum lengths and lateral angles differed significantly among trajectories; the maximum length, but not the lateral angle, differed significantly between male and female subjects. The influence of the iliac wing was more significant in male than in female subjects. The iliac wing had a greater effect on screws implanted along the pedicle axis than on screws for which the trajectories commenced at Dus entry point and passed through the center of the pedicle.nnnCONCLUSIONSnThis study elucidates the influence of the iliac wing on L5 PS fixation. Careful attention is required when implanting PSs, especially in male patients. The combined use of Dus technique and a percutaneous method for PS implantation effectively reduces the influence of the iliac wing. To minimize the complications of PS fixation further, preoperative simulation of fixation for each patient is very important.

A Novel Knotless Barbed Suture Technique for Traumatic Thoracolumbar Fracture in Posterior Surgery

BACKGROUNDnSurgical wound closure directly influences spinal surgical efficiency and several postoperative complications. The traditional suture technique is time-consuming and associated with greater rates of complications. Bidirectional absorbable barbed sutures seem to compensate for some of the limitations of traditional suture; however, they rarely are reported in spinal surgery. We designed a novel suture technique for use in thoracolumbar spinal surgery.nnnMETHODSnThe data of 189 patients with traumatic thoracolumbar fractures were analyzed between bidirectional barbed suture closure and traditional interrupted suture closure. Data of operative time, wound closure time, length of incision, intraoperative blood loss, complications of wound dehiscence and postoperative hematoma, cost, and neurologic status were collected.nnnRESULTSnNo significant differences were observed in the baseline demographics of included patients. Compared with the traditional suturing group, the barbed sutures decreased the mean operative time (Pxa0= 0.037), suture time (P < 0.01), and mean suturing time (P < 0.01) significantly, although no statistically significant differences were found in blood loss (Pxa0= 0.724) and neurologic functional scores (preoperative: Pxa0= 0.901; 3 months after surgery: Pxa0= 0.208; final follow-up assessments: Pxa0= 0.163), and no statistically significant differences were found in rates of postoperative infection, hematoma, and wound dehiscence.nnnCONCLUSIONSnOur findings suggest that the novel knotless barbed suture has comparable strength to traditional sutures, with the advantage of less suturing time. It is an efficient, safe technique, and alternative choice for patients with thoracolumbar fracture after posterior surgery.

Factors associated with cervical spine alignment in an asymptomatic population

BACKGROUNDnCervical sagittal imbalance compromises health-related quality of life and can lead to myriad incapacitating symptoms through compression of the spinal cord. Questions regarding which parameters play primary roles in the progression of cervical sagittal imbalance and which might be compensatory factors remain unanswered.nnnMETHODSnThis study enrolled 246 asymptomatic volunteers from July 2016 to June 2018. After demographic and radiologic parameters were measured, the data were analyzed using correlation coefficient test and multiple regression analysis. A predictive equation was assessed with variance analysis, residual analysis, collinearity analysis, and a paired t test.nnnRESULTSnAverage values are as follows: orbital tilt, 64xa0± 6°; orbital slope (OS), 15 ± 6°; C0-C2 lordosis (C0C2), 28xa0± 8°; cervical lordosis (CL), 5 ± 11°; C2-C7 sagittal vertical axis (C2C7SVA), 15 ± 8 mm; T1 slope (TS), 17 ± 6°; thoracic inlet angle, 69 ± 8°; thoracic kyphosis, 34 ± 9°; lumbar lordosis, 50 ± 10°; sacral slope, 38 ± 7°; pelvic index, 48 ± 9°; sagittal vertical axis, 10 ± 19 mm. Correlations of C2C7SVA were observed with body mass index (BMI), OS, C0C2, CL, and TS. The validated predictive equation was: C2C7SVA = 0.38 × BMI - 0.73 × OS + 0.73xa0× C0C2 + 0.15 × CL + 0.18 × TS - 6.53.nnnCONCLUSIONSnBMI, OS, C0C2, CL, and TS were primary influencers in the progression of cervical sagittal imbalance and established a predictive equation of asymptomatic population, which can provide clinical advice and remind surgeons of the primary influencers of reconstructive surgery for better prognoses.

Biomechanical properties of novel transpedicular transdiscal screw fixation with interbody arthrodesis technique in lumbar spine: A finite element study

Purpose The purpose of this study was to investigate finite element biomechanical properties of the novel transpedicular transdiscal (TPTD) screw fixation with interbody arthrodesis technique in lumbar spine. Methods An L4–L5 finite element model was established and validated. Then, two fixation models, TPTD screw system and bilateral pedicle screw system (BPSS), were established on the validated L4–L5 finite element model. The inferior surface of the L5 vertebra was set immobilised, and moment of 7.5 Nm was applied on the L4 vertebra to test the range of motion (ROM) and stress at flexion, extension, lateral bending and axial rotation. Results The intact model was validated for prediction accuracy by comparing two previously published studies. Both of TPTD and BPSS fixation models displayed decreased motion at L4–L5. The ROMs of six moments of flexion, extension, left lateral bending, right lateral bending, left axial rotation and right axial rotation in TPTD model were 1.92, 2.12, 1.10, 1.11, 0.90 and 0.87°, respectively; in BPSS model, they were 1.48, 0.42, 0.35, 0.38, 0.74 and 0.75°, respectively. The screws peak stress of above six moments in TPTD model was 182.58, 272.75, 133.01, 137.36, 155.48 and 150.50 MPa, respectively; and in BPSS model, it was 103.16, 129.74, 120.28, 134.62, 180.84 and 169.76 MPa, respectively. Conclusion Both BPSS and TPTD can provide stable biomechanical properties for lumbar spine. The decreased ROM of flexion, extension and lateral bending was slightly more in BPSS model than in TPTD model, but TPTD model had similar ROM of axial rotation with BPSS model. The screws peak stress of TPTD screw focused on the L4–L5 intervertebral space region, and more caution should be put at this site for the fatigue breakage. The translational potential of this article Our finite element study provides the biomechanical properties of novel TPTD screw fixation, and promotes this novel transpedicular transdiscal screw fixation with interbody arthrodesis technique be used clinically.