Abstract:The effect of functional overloading on the regenerating process of injured skeletal muscle was investigated in 10-week-old male mice (C57BL/6J). Functional overloading on soleus of both hindlimbs was performed by cutting the distal tendons of plantaris and gastrocnemius muscles for 2 weeks before cardiotoxin (CTX) injection as the preconditioning and also during 10 weeks of recovery. To activate the necrosisregeneration cycle, 0.1 ml of 10-µM CTX was injected into soleus muscle. The mean values of absolute muscle weight and the percentage of Pax7-positive nuclei in soleus were increased by the preconditioning. These values, as well as total muscle protein content, in the group with CTX injection plus overloading were larger than in the group with CTX injection alone. Fibers with central nucleus were noted in the group with CTX injection with or without overloading. The rate of disappearance of fibers having central nucleus during recovery was stimulated by overloading. Histological analyses revealed that the regeneration of injured soleus muscle with overloading proceeded more rapidly than the muscle without overloading. These results, in combination with previous lines of evidence, strongly suggest that functional overloading may facilitate the regeneration of injured skeletal muscles.
Effects of administration of granulocyte colony-stimulating factor (G-CSF) on the regeneration of injured mammalian skeletal muscles were studied in male C57BL/6J mice. Muscle injury was induced by injection of cardiotoxin (CTX) into tibialis anterior muscles bilaterally. G-CSF was administrated for 8 consecutive days from 3 days before and 5 days after the injection. Significant decreases of wet weight and protein content were noted in the necrotic muscle with CTX injection. A large number of the regenerating fibers having central nucleus were observed 7 days after the injection. The regeneration of injured muscle was further facilitated by the G-CSF treatment. Population of Pax7-positive nuclei was increased by the G-CSF treatment at day 7. Phospho-Akt and phospho-glycogen synthase kinase 3alphabeta (GSK3alphabeta) signals were also activated by G-CSF-administrated group during the regenerative process. It was suggested that G-CSF treatment may facilitate the regeneration of injured skeletal muscles via the activation of Akt/GSK3alphabeta signals.
Abstract:Introduction: The purpose of this study was to investigate the long-term incidence of lumbar disc degeneration and Modic changes in the non-fused segments of patients with adolescent idiopathic scoliosis (AIS) who previously underwent spinal fusion.Methods: Study subjects consisted of 252 patients with AIS who underwent spinal fusion between 1968 and 1988. Of 252 patients, 35 subjects underwent lumbar spine MRI and whole spine X-ray examination. The mean patient age at the time of follow-up was 49.8 years, with an average follow-up period of 35.1 years. We classified the subjects into two groups based on the lowest fused vertebra: H group whose lowest fused vertebra was L3 or higher levels and L group whose lowest fused vertebra was L4 or lower levels.Results: The L group had significantly advanced disc degeneration on MRI. There was no significant difference between two groups in Modic changes. The L group showed less lumbar lordosis than the H group (H group: 48.1 degrees; and L group: 32.1 degrees) and greater SVA (H group: 1.2 cm; and L group: 5.5 cm).Conclusions: In AIS patients, 35 years after spinal fusion surgery on average, we evaluated lumbar disc degeneration and Modic changes of the non-fused segments. In patients with the lowest fusion level at L4 or lower, there were reduced lumbar lordosis, considerable SVA imbalance, and severe disc degeneration compared with those with the lowest fusion level at L3 or higher. The lowest fusion level at L3 or higher is recommended to reduce disc degeneration in midlife.
Abstract:Introduction: This study compared traditional manual methods and power tool use with regard to the speed and accuracy of percutaneous pedicle screw (PPS) placement and determined the advantages associated with the use of power tools.Although the indication of PPS placement in minimally invasive spine stabilization (MISt) procedures has been recently expanded, there are no reports on PPS insertion using a power tool.Methods: We evaluated 35 patients who underwent PPS insertion using a power tool during MISt procedures. On one side, PPS insertion was performed using the manual (M) method, whereas on the contralateral side, insertion was performed using the power tool (P) method. We assessed the number of implanted PPSs, time taken to implant PPSs after guidewire insertion, and accuracy of PPS placement as ranked postoperatively using computed tomography images.Results: A total of 294 PPSs were inserted (147 using the M method and 147 using the P method). The mean PPS insertion time was 10.5 s using the P method and 27.4 s using the M method. The time required for inserting a screw using the P method remained consistent in the range of 10-15 s, whereas the time using the M method tended to increase from the second screw onward, with a range of 25-30 s. With regard to PPS insertion accuracy, a 2 mm or more pedicle breach was noted in 2 (1.4%) case after the P method and in 2 (1.4%) case after the M method.Conclusions: PPS placement using power tools has the potential to save the surgical time during MISt procedures.
Abstract:Introduction: This study aimed to evaluate morphological changes in the L5 nerve roots in control and symptomatic patients using magnetic resonance myelography [MRM]. Moreover, the utility of MRM for the diagnosis of intraforaminal or extraforaminal lesions in patients with L5 radiculopathy was evaluated using healthy subjects as controls.Methods: Of 270 subjects who underwent MRM of the lumbar spine at our institution between April 2007 and December 2010, 135 patients (78 men and 57 women; average age: 61.3 years) with no history of spinal surgeries and nerve roots without infections, tumors, or malformations were selected for this study.The end-point measurements included the bifurcation angle of inclination (proximal tilting angle [PTA]) of the L5 nerve root as observed via MRM, lateral angle of inclination (lateral tilting angle [LTA]), bifurcation diameter (proximal nerve root width [PW]), and dorsal root ganglion (DRG) diameter (DRG width [DW]). DW ratio was then calculated for healthy controls and symptomatic subjects. We measured each parameter using the image information unification system ShadeQuest (Yokogawa, Tokyo, Japan). Two spinal surgeons conducted the magnetic resonance imaging evaluation.Results: Swelling of the L5 DRG was detected in cases with intraforaminal or extraforaminal stenosis. With regard to the cutoff value of 6.5 mm for L5 DW, foraminal stenosis can be confirmed if DW is ! 6.5 mm or more via MRM. In cases where L5 DRG was swollen to ! 1.2 times the size in healthy subjects, L5 radiculopathy with foraminal lesions can be diagnosed.Conclusions: Our findings indicated that 3D MRM is a noninvasive technique and a useful tool for the diagnosis of intraforaminal or extraforaminal lesions in the lumbar spine. Therefore, it can be combined with other diagnostic methods used for the identification of intraforaminal or extraforaminal L5 nerve root lesion.
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