BACKGROUND: Mechanic pressure could cause neurocyte death. Both direct mechanic injury and complex pathophysiological mechanism can induce the pathological changes of axon and neuronal soma. OBJECTIVE: To observe the relationship between ultrastructural changes and pressure degree of neurocyte and neurocyte damage. DESIGN: A randomized controlled observational study using experimental animals as study subjects.MATERIALS:The study was conducted in the Central Laboratory of Ruikang Hospital affiliated to Guangxi Traditional Chinese Medical University from December 2002 to August 2003.SUBJECTS:Fourty-eight male New Zealand rabbits with a bodymass of (2.45 ± 0. 28) kg were randomly divided into control group, mild pressure group and severe pressure group with 16 rabbits in each group.METHODS:Animal models with mild and severe cervical spinal cord chronic pressure were established in rabbits. Control group was pseudo-operation group. Spinal cord observation under optical microscope and electron microscope, neurocyte apoptosis analysis (TUNEL method), neuron counting, and the section size of the neuron were analyzed respectively.MAIN OUTCOME MEASURES: Main results: observational results under optical microscope of each group. Subordinate results: ① observational results under electron microscope of each group; ② neurocyte apoptosis analysis RESULTS: After chronic pressure in the spinal cord of rabbits, phenomena like neuron atrophy,loss,reduced section size,and neuron and neurocyte apoptosis appeared. The morphology of neurons in control group was normal and the quantity was quite a lot, which was (40 ± 2), and the neuron section size was(41.24 ± 15.61) μm2.The number of neuron of mild pressurc group was(27 ± 2), and the neuron section size was(20. 82 ± 6.57) μm2. The number of neurons of severe pressure group was (22± 2), and the neuron section size was( 17. 96 ± 9.03 ) μm2. The difference between mild, severe pressure group and control group was significant( P ＜ 0.01),while the difference between mild and severe pressure groups was insignificant(P ＞ 0. 05 ). The ultrastructural changes of neurons after chronic pressure were reduced volume of soma, unclear nucleolus and reduced rough endoplasmic reticulum. The lamellar structure of spinal sheath was loose with vacuole, and the cell organs in axial plasma were reduced or lost.CONCLUSION: The ultrastructure of neurocyte changes after chronic pressure in spinal cord. The more serious the pressure is, the more serious the neurocyte damages are. Cell apoptosis exists after chronic pressure in spinal cord.

BACKGROUND: Implantation of bone marrow mesenchymal stem cells (BMSCs) is a potential alternative for promoting bone defects healing or osseointegration in osteoporosis. However, the reactive oxygen species (ROS) accumulated and excessive inflammation in the osteoporotic microenvironment could weaken the self-replication and multi-directional differentiation of transplanted BMSCs. METHODS: In this study, to improve the hostile microenvironment in osteoporosis, Poloxamer 407 and hyaluronic acid (HA) was crosslinked to synthetize a thermos-responsive and injectable hydrogel to load MnO2 nanoparticles as a protective carrier (MnO2 @Pol/HA hydrogel) for delivering BMSCs. RESULTS: The resulting MnO2 @Pol/HA hydrogel processed excellent biocompatibility and durable retention time, and can eliminate accumulated ROS effectively, thereby protecting BMSCs from ROS-mediated inhibition of cell viability, including survival, proliferation, and osteogenic differentiation. In osteoporotic bone defects, implanting of this BMSCs incorporated MnO2 @Pol/HA hydrogel significantly eliminated ROS level in bone marrow and bone tissue, induced macrophages polarization from M1 to M2 phenotype, decreased the expression of pro-inflammatory cytokines (e.g., TNFa, IL-1b, and IL-6) and osteogenic related factors (e.g., TGF-b and PDGF). CONCLUSION This hydrogel-based BMSCs protected delivery strategy indicated better bone repair effect than BMSCs delivering or MnO2 @Pol/HA hydrogel implantation singly, which providing a potential alternative strategy for enhancing osteoporotic bone defects healing.

Objective:To evaluate the efficacy of arthroscopic suture combined with perforator tendon double reduction and Endobutton plate technique for the treatment of tibial avulsion fracture of posterior cruciate ligament (PCL).Methods:A retrospective case series study was conducted to analyze the clinical data of 32 patients with tibial avulsion fracture of PCL, who were admitted to First People′s Hospital of Huizhou from January 2018 to October 2022. There were 19 males and 13 females, with age range of 18-65 years [(42.8±15.0)years]. By the Meyers-Mckeever classicfication, 27 patients were type II, and 5 type III. All the patients were treated with arthroscopic suture combined with perforator tendon double reduction and Endobutton plate technique to fix PCL tibial avulsion fracture at the insertion point. The fracture reduction was observed by X-ray films before discharge. Three months postoperatively, the fracture healing was observed by CT imaging, and the stability of knee joint was evaluated by posterior drawer test. The knee active range of motion, visual analogue score (VAS), Lysholm score, and International Knee Documentation Committee (IKDC) score were used to evaluate the pain and knee function before operation, at 3 months after operation, and at the last follow-up. Intraoperative and postoperative complications were observed.Results:All the patients were followed up for 6-36 months [(19.7±8.7)months]. The X-ray films showed satisfactory reduction of the fracture before discharge, and the CT showed that the fracture line was blurred to various degrees at 3 months after operation. Two patients had degree I positive posterior drawer test at 3 months after operation, and the rest were negative. The knee active range of motion was improved from 54.2°(45.0°, 70.0°) preoperatively to 124.8°(120.0°, 130.0°) at 3 months postoperatively and to 130.6°(125.0°, 135.0°) at the last follow-up (all P<0.01). The VAS was decreased from 5.1(3.0, 7.0)points preoperatively to 1.2(1.0, 2.0)points at 3 months postoperatively and to 0.1(0.0, 0.0)points at the last follow-up (all P<0.01). The Lysholm score was improved from 31.2(24.3, 37.0)points preoperatively to 73.6(69.3, 78.8)points at 3 months postoperatively and 92.6(91.0, 95.0)points at the last follow-up (all P<0.01). The IKDC score was increased from (20.9±7.1)points preoperatively to (59.2±8.9)points at 3 months postoperatively and to (77.5±7.0)points at the last follow-up (all P<0.01). Compared with 3 months after operation, the last follow-up showed significantly improved knee active range of motion, significantly decreased VAS, and significantly increased Lysholm score and IKDC score (all P<0.05). No intraoperative nerve vascular injury, postoperative incision infection, or lower limb venous thrombosis was observed. Conclusion:Arthroscopic suture combined with perforator tendon double reduction and Endobutton plate technique can achieve good reduction and high healing rate in patients with tibial avulsion fracture of PCL, with improved joint mobility, relieved pain, good recovery of knee joint function, and few complications.