MiR-34a Inhibits Spinal Cord Injury and Blocks Spinal Cord Neuron Apoptosis by Activating Phatidylinositol 3-kinase (PI3K)/AKT Pathway Through Targeting CD47.

OBJECTIVE: Dysregulation of miR-34a has been reported for its implication in neuronal development. This study aims to explore the effect and possible mechanism of miR-34a on neuron apoptosis induced by Spinal Cord Injury (SCI). MATERIALS AND METHODS: SCI model was established using Allen's weight-drop method and rats in the sham group were performed with laminectomy without weight-drop injury. Basso Bcattie Bresnahan (BBB) rating scale was applied to evaluate the locomotor function of rats. Pathological changes of spinal cord tissues in SCI rats were observed after hematoxylin and eosin (HE) staining. Rats were separately injected with miR-34a agomir, miR-34a agomir NC, si-CD47 and si- CD47 NC before their spinal cord tissues were collected for terminal-deoxynucleoitidyl Transferase Mediated nick end labeling (TUNEL) staining. Expressions of miR-34a, si-CD47, apoptosis related proteins and AKT pathway related proteins were measured by quantitative reverse transcription- polymerase chain reaction (qRT-PCR) and western blot. RESULTS: SCI rat models were successfully established evidenced by decreased BBB scores and HE staining. Injection of miR-34a agomir and/or si-CD47 could suppress neuron cell apoptosis, with deceased apoptotic index (AI) and pro-apoptotic protein (cleaved caspase-3 and Bax) levels, and increased expressions of anti-apoptotic proteins (Bcl-2 and Mcl-1). Phosphorylated levels of phatidylinositol 3-kinase (PI3K) and AKT were further increased in rats injected with miR-34a agomir and si-CD47, compared with miR-34a agomir or si-CD47 injection alone. CONCLUSION: MiR-34a can downregulate CD47 expression to activate PI3K/AKT signal pathway, and thus inhibit SCI induced spinal neuron apoptosis.

Surgical factors contributing to nonunion in femoral shaft fracture following intramedullary nailing / 中华创伤杂志(英文版)

<p><b>PURPOSE</b>To explore the possible surgical factors related with nonunion in femoral shaft fracture following intramedullary nailing.</p><p><b>METHODS</b>We retrospectively analyzed totally 425 patients with femoral shaft fracture in level I urban trauma center, including 254 males and 171 females, with an average age of 37.6 (ranging from 21 to 56) years old. The inclusion criteria included: (1) traumatically closed fracture of femoral shaft, with pre- operative films showing non-comminuted fracture, such as transverse fracture, oblique fracture or spiral fracture; (2) closed reduction and fixation with interlocking intramedullary nail at 3-7 days after trauma; (3) complete follow-up data available. The relationship between the following factors (fracture site, reduction degree, direction of nail insertion and nail size) and nonunion was studied.</p><p><b>RESULTS</b>The incidence of femoral nonunion was 2.8% in patients with closed simple fracture undergoing interlocking intrameduallary nailing, including 11 cases of hypertrophic nonunion. Nonunion was related significantly to distal fracture, unsatisfactory reduction and unreamed nail (p < 0.05). There was no significant difference between antegrade nail and retrograde nail (p > 0.05).</p><p><b>CONCLUSIONS</b>Nonunion in femoral shaft facture following interlocking intramedullary nailing is related to fracture site, fracture reduction and nail diameter. The choice of reamed nails or unreamed nails depends on the fracture site and reduction degree.</p>