[Construction and stability analysis of finite element model for spinal canal reconstruction with miniplates fixation].

OBJECTIVE: To establish the finite element model of spinal canal reconstruction and internal fixation,analysis influence of spinal canal reconstruction and internal fixation on spinal stability,and verify the effectiveness and reliability of spinal canal reconstruction and internal fixation in spinal canal surgery. METHODS: A 30-year-old male healthy volunteer with a height of 172 cm and weight of 75 kg was selected and his lumbar CT data were collected to establish a finite element model of normal lumbar L3-L5,and the results were compared with in vitro solid results and published finite element analysis results to verify the validity of the model. They were divided into normal group,laminectomy group and spinal canal reconstruction group according to different treatment methods. Under the same boundary fixation and physiological load conditions,six kinds of activities were performed,including forward bending,backward extension,left bending,right bending,left rotation and right rotation,and the changes of range of motion (ROM) of L3-L4,L4-L5 segments and overall maximum ROM of L3-L5 were analyzed under the six conditions. RESULTS: The ROM displacement range of each segment of the constructed L3-L5 finite element model was consistent with the in vitro solid results and previous literature data,which confirms the validity of the model. In L3-L4,ROM of spinal canal reconstruction group was slightly increased than that of normal group during posterior extension(>5% difference),and ROM of other conditions was similar to that of normal group(<5% difference). ROM in laminectomy group was significantly increase than that in normal group and spinal canal reconstruction group under the condition of flexion,extension,left and right rotation. In L4-L5,ROM in spinal canal reconstruction group was similar to that in normal group(<5% difference),while ROM in laminectomy group was significantly higher than that in normal group and spinal canal reconstruction group(>5% difference). In the overall maximum ROM of L3-L5,spinal canal reconstruction group was only slightly higher than normal group under the condition of posterior extension(>5% difference),while laminectomy was significantly higher than normal group and spinal canal reconstruction group under the condition of anterior flexion,posterior extension,left and right rotation(>5% difference). The changes of each segment ROM and overall ROM of L3-L5 showed laminectomy group>spinal canal reconstruction group>normal group. CONCLUSION: Laminectomy could seriously affect biomechanical stability of the spine,but application of spinal canal reconstruction and internal fixation could effectively reduce ROM displacement of the responsible segment of spine and maintain its biomechanical stability.

[Role and mechanism of endoplasmic reticulum stress response induced by wear particles in osteolysis].

OBJECTIVE: To analyze the role of endoplasmic reticulum stress response in the development of osteoblast apoptosis and osteolysis in osteolytic bone tissue, and to explore the causes of artificial joint loosening, so as to provide new ideas and theoretical basis for the prevention and treatment of artificial joint loosening. METHODS: The animal model of osteolysis induced by wear particles was established by mouse skull, and randomly divided into 4 groups, 7 rats in each group:group 1, blank control group;group 2, wear particles tial6v4 nano alloy powder (TiNPs) group;group 3, endoplasmic reticulum stress response positive control (TiNPs+Tg) group; group 4, endoplasmic reticulum stress response inhibitor (TiNPs+4-PBA) group. The pathological changes of osteolysis were observed by toluidine blue staining, HE staining and ALP staining;the expression of endoplasmic reticulum stress response marker protein was detected by Western Blotting;the apoptosis of osteoblasts in osteolytic skull tissue was detected by TUNEL and Caspase-3 immunohistochemistry. RESULTS: Wear particles TiNPs can induce osteolysis in vitro, aggravate the infiltration of inflammatory cells and inhibit the differentiation and maturation of osteoblasts. At the same time, wear particles can also up regulate the markers of endoplasmic reticulum stress response and promote the apoptosis of osteoblasts in osteolytic bone tissue. After adding 4-PBA, an inhibitor of endoplasmic reticulum stress (4-PBA), on the basis of wear particles TiNPs, the symptoms of osteolysis were significantly relieved, bone erosion and inflammatory infiltration were significantly reduced, the differentiation and maturation of osteoblasts were improved, the number of apoptotic osteoblasts decreased sharply, and the expression of endoplasmic reticulum stress marker protein gradually decreased. CONCLUSION: Endoplasmic reticulum stress is involved in the formation of osteolysis and plays an important role in the occurrence and development of osteolysis. At the same time, endoplasmic reticulum stress can be used as a new therapeutic target to provide new ideas and methods for clinical reversal or treatment of osteolysis and aseptic loosening.

[Progress on laminoplasty in spinal canal disease].

Surgery is the preferred method for the treatment of spinal canal disease, surgical method involves laminectomy and laminoplasty. The ideal spinal surgery not only should fully expose the spinal canal, completely resect the occupied position and remove the spinal cord compression, but also should maintain the stability of spinal biomechanics. Because of the different realization of clinician to safeguard and rebuild the spinal stabilization during opertion of spinal canal disease, and choice of surgical method and how to maintain the stability of spine biomechanics has become a hot of research in this field. Many scholars have studied it in order to reduce the influence of laminectomy on the spinal stability. Laminoplasty can directly relieve the nerve roots compression caused by increasing or reconstruction of vertebral canal volume, and allow the migration of spinal cord to dorsum and depart from disc and vertebral body. Laminoplasty not only can fully expose and decompress during operative, but also may prevent the postoperative spinal instability. In addition to these condition of extensive disease, severe bone destruction or combined with osteoporosis, the laminoplasty is the most ideal method for single spinal canal disease in theoretically.

Comparison of the short-term efficacy between docetaxel plus carboplatin and 5-fluorouracil plus carboplatin in locoregionally advanced nasopharyngeal carcinoma.

OBJECTIVE: Platinum-based chemotherapy in combination with radiotherapy is a standard treatment strategy for locoregionally advanced nasopharyngeal carcinoma (NPC). This study aimed to investigate the long-term efficacy and tolerability of inductive chemotherapy with docetaxel plus carboplatin (TC) or 5-fluorouracil plus carboplatin (FC) followed by concurrent radiation therapy in patients with NPC. METHODS: Patients (N=88) were randomized to receive TC or FC as inductive therapy followed by concurrent radiotherapy (60-70 Gy) with two cycles of carboplatin (area under the curve =5 mg·h/L). Patients were followed up for 8 years. Primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS), toxicity, tumor response, distant metastasis-free survival, and local recurrence-free survival. RESULTS: At the end of the follow-up period, 31 patients died, 32 had disease progression, eleven had cancer recurrence, and 25 had distant metastasis. Overall, there was no difference between treatment groups with regard to response or survival. We found that following induction and concurrent chemoradiotherapy, the majority of patients showed a complete response (~96%-98% for induction therapy and 82%-84% for comprehensive therapy) to both therapies. PFS and OS were also similar between groups. The rate of PFS was 63.6% for both FC and TC and that of OS was 65.9% and 63.5%, respectively. The overall incidence of grade 3-4 adverse events in the TC group (20.5%) was higher than in the FC group (10.7%). Neutropenia and leukopenia were the most common grade 3-4 adverse events in the TC group, and mucositis was the most common in the FC group. CONCLUSION: These data indicate that TC and FC therapies have similar efficacy in treating locally advanced NPC and both are well tolerated.

[Progress on microRNA in aseptic loosening of prostheses].

MicroRNA(miRNA) is a class of non-coding RNA that plays an important role in gene expression and controlling. In recent years,the role of miRNA in the development of the disease has aroused great interest. Abnormal osteoclastogenesis and persistent inflammatory response induced by wear particles or osteoblast differentiation and maturation is the main cause of aseptic loosening in joint replacements. New researches shows that persistent inflammatory response, osteoclastogenesis and osteoblast differentiation are closely associated with miRNA, suggesting that there are certain relations between miRNA and aseptic loosening of prostheses. Additionally, the alteration of the expression levels of some miRNA may be curative for aseptic loosening. With the findings of the new miRNA targets, the important role of miRNA is further confirmed.

[Progress on the relationship between wear debris-induced apoptosis and aseptic loosening of prosthesis].

Aseptic looseningis is one of the most frequent long-term complications after joint replacement, which limits the service lire of prosthesis. A lot of studies have been focused on macrophage, osteoblast, osteoclast and fibroblast in interface membranes around prostheses recently. Aseptic loosening of orthopedic implants used in joint replacement results from bone loss that occurs through the resorptive activity of inflammatory cells activated by the presence of wear particles. Apoptosis has been observed in the periprosthetic site and it has been interpreted as a sign of resolution of inflammation suggesting that apoptosis-related events are indeed associated with periprosthetic osteolysis,targeting the Apoptosis pathway may lead to novel therapeutic approaches for the treatment of aseptic prosthesis loosening. In this thesis,the relationship between wear debris-induced apoptosis and aseptic loosening of prostheses are expounded in detail.

[Effects of body position changes on frequency domain correlative cardiogram in pilots].

OBJECTIVE: To study the effects of the body position changes on FCG in pilots so as to explore the possibility of using FCG as an indicator of medical monitoring and medical support. METHOD: 65 pilots were examined in 4 different body positions, i.e. supine position, head-down position, standing position and sitting position. Twelve channel routine electrocardiogram was recorded synchronously, and their complaints were also recorded. RESULT: The grade distribution and abnormal cases of the FCG varied with the body positions. The orders of changing magnitude were: the standing position, the head-down position, the sitting position and the supine position. The changes accorded with that of 12 channels routine ECG synchronously recorded and complaints of the subjects. CONCLUSION: The FCG was an objective index representing the cardiac functional status.

[Effects of head down tilt on intra-ocular pressure, near vision, and visual field and the protection effect of Chinese herbs].

Objective. To observe the influences of 21 d head down tilt (HDT) bed rest on the intra-ocular pressure, visual field and near vision in human and to study the countermeasure of Chinese herb against weightlessness. Method. Ten subjects were randomly divided into control group and Chinese herb group. -6 degrees HDT was used to simulate weightlessness. Intra-ocular pressure, near vision and vision field were measured before, during and after bed rest in both groups. Result. Intra-ocular pressure and near vision showed a wave-like decrease change during bed rest, and there exists a certain coherence between them. Visual field showed no obvious changes. Taking Chinese herb was able to antagonize the decreasing of intra-ocular pressure and near vision during various phases of bed rest. Conclusion. 1) Bed rest could lead to the decreasing of intra-ocular pressure and near vision; 2) Taking Chinese herb was able to antagonize the negative influences of bed rest on visual function.