ABSTRACT
A rapid resolution liquid chromatography quadruple time-of-flight mass spectrometric ( RRLC-Q-TOF/MS) method combined with multivariate statistical analysis was applied to investigate the changes of endogenous metabolites in murine urine before and after ultraviolet B ( UVB ) irradiation for the purpose of discussing the physiological mechanism of acute injury caused by UVB radiation. A narrow-band UVB ( NB-UVB) (TL-01, peak value 312nm) was used to establish the acute light damage model. The urine samples were centrifuged before four times dilution treatment, subsequently the diluted urine samples were separated on a Supelco Ascentis Express C18 column using water (0. 1% formic acid) and acetonitrile as mobile phase by gradient elution. The differences metabolites with major contribution for grouping were found out based on the metabolic profiling analysis of principal component analysis ( PCA) and cluster analysis ( CA) , which could illustrate their possible mechanism of actions by means of relevant pathways. A prediction model was built to investigate the forecasting ability of the acute photo damage induced by UVB irradiation through the partial least square discriminant analysis ( PLS-DA ) . The results of multivariate statistical analysis showed that the blank control group was separated from UVB model group quite well, 11 endogenous metabolites were identified as the potential biomarkers through comparison with the database, tandem mass spectrum data and standard substance, which indicated the UVB radiation may affect the sphingolipid metabolism, nucleic acid metabolism, linoleic acid metabolism and amino acid metabolism pathways. These different metabolites could be helpful for diagnosing the light damage induced by UVB radiation
ABSTRACT
Pedicle screw fixation is biomechanically most reliable for reconstruction of the cervical spine, which can ef?fectively restore cervical sagittal profiles, provide rigid fixation and higher fusion rate. Because of the large individual differ?ences in cervical pedicle, vertebral artery and nerve root, preoperative evaluation should be individualized. Cervical pedicle screw techniques include freehand technique and the computer-assisted navigation technology developed recently. Although complications associated with cervical pedicle screw fixation cannot be completely obviated, they can be minimized by com?bination of sufficient preoperative imaging studies of the pedicles and meticulous surgical techniques of screw placement. Cervical pedicle screw fixation techniques have been used in the treatment of various cervical disorders, with fewer complica?tions and good clinical efficacy, and a wide range of clinical applications.
ABSTRACT
Objective To evaluate the effects of posterior segmental pedicle screw instrumentation and augmentation using calcium sulphate cement in treatment of Denis type B thoracolumbar burst fractures.Methods Forty patients with Denis type B thoracolumbar burst fracture treated between January 2011 and December 2012 were reviewed retrospectively.Twenty patients received posterior short-segment pedicle screw fixation in conjunction with screw placement at the level of fracture and calcium sulphate augmentation without posterolateral fusion (combined treatment group),but 20 patients underwent traditional short-segment pedicle screw fixation (conventional treatment group).Radiographs and CT scans evaluated local kyphotic angle on the spot of injury,anterior height of the injured vertebra,and canal encroachment before and after operation and at final follow-up.Meanwhile,visual analogue score (VAS),Oswestry disability index (ODI),and neurologic status based upon ASIA 2000 were assessed.Results Mean follow-up period was 15 months (range,12-24 months).Vertebral height restoration was equivalent of the two groups immediately after operation,but better result of kyphosis correction was found in treatment group than in control group (P ＜ 0.05).Anterior vertebral height and kyphotic angle significantly improved in treatment group compared to control group at final follow-up (P ＜ 0.05).Clinical and neurologic outcome evaluation were similar between the two groups.No implant failure occurred at follow-up.Conclusion For Denis type B thoracolumbar burst fractures,posterior segmental pedicle screw fixation augmented with calcium sulphate is effective for reducing correction loss and implant failure,compensating for the deficiencies of conventional fixation.
ABSTRACT
Objective To evaluate the clinical efficacy of treatment of severe thoracolumbar burst fractures by posterior short-segment instrumentation without spinal fusion and assess radiographic imaging and function recovery after surgery.Methods Thirty-eight patients with severe monosegmental thoracolumbar burst fractures treated between July 2011 and March 2013 were analyzed retrospectively.Operation procedures were posterior short-segment pedicle screw distraction reduction and fixation combined with screw insertion to the injured vertebrae and calcium sulphate augmentation.In addition,there was no need for posterolateral interbody fusion.X-ray and CT were performed before and after operation to evaluate local kyphotic angle,anterior fractured vertebral body height and canal encroachment.Visual analogue scale (VAS) and Oswestry disability index (ODI) were assessed before and after operation as well as in follow-up.Results All patients were followed up for average 14 months (range,3-20 months).Local kyphotic angle was (21.2 ±4.3)° before operation,(3.5 ± 1.8)°immediately after operation,and (4.8 ± 2.7) ° in final follow-up.Relative anterior vertebral height was (54.8 ± 14.6)％ before operation,(91.7 ± 8.0)％ after operation,and (87.2 ± 6.0)％ in final follow-up.Mean canal encroachment was (48.0 ± 4.5)％ preoperatively,(23.8 ± 7.8)％postoperatively,and (8.8 ± 4.6) ％ in final follow-up.In final follow-up,six patients with American Spinal Injury Association (ASIA) grade C on admission showed improvement to grade D (n =2) and grade E (n =4) ; 10 patients with ASIA grade E on admission showed improvement to grade E; 22 patients with grade E had no changes.ODI and VAS scored 15.5 ±8.8 and 2.3 ±0.8 in final follow-up with substantial improvement from those before operation (P ＜ 0.01).Complications from internal fixation were not found during follow-up.Conclusion Posterior short-segment fixation without fusion is one of the foremost effective methods for severe thoracolumbar burst fractures,for it can effectively restore the sagittal spinal alignment and the fractured vertebral body height.