Analysis of delayed infection of proximal junctional zone after posterior spinal internal fixation and its treatment strategy / 中国骨伤

<p><b>OBJECTIVE</b>To explore the features and treatment strategy of delayed infection of proximal junctional zone after posterior spinal internal fixation.</p><p><b>METHODS</b>The clinical data of 1325 patients underwent posterior spinal internal fixation were retrospectively analyzed. Delayed infection occurred in 10 patients, among which 4 infections occurred at the proximal junction (non-operative site). And these 4 patients were treated with combined broad-spectrum antibiotics. Their clinical symptoms and signs, lab tests, MRI findings, pathology findings, and clinical effects were analyzed.</p><p><b>RESULTS</b>All four patients were followed up from 6 months to 4 years. No infection recurrence was found. All patients obtained satisfactory results after hospital discharge. No nerve injury was found. One patient developed kyphosis in the proximal junctional zone 2 years after the operation. According to the criteria of N.Nakano and T.Nakano, 3 cases obtained excellent results, while 1 poor.</p><p><b>CONCLUSIONS</b>The incidence rate of delayed infections was rare after spinal operation. Delayed infections occurred in proximal junctional zone may be attributed to the stress concentration of adjacent segments after fixation and the degeneration of adjacent segments, thus forming inflammation areas. For refractory lumbar and back pains, an elevated blood sedimentation rate, C-reactive protein level, MRI manifestation and focal pathology would be helpful for establishing a definite diagnosis. Full course of combined broad-spectrum antibiotics in treating the infection can lead to satisfactory clinical results.</p>

p21 is Responsible for Ionizing Radiation-induced Bypass of Mitosis / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To explore the role of p21 in ionizing radiation-induced changes in protein levels during the G2/M transition and long-term G2 arrest.</p><p><b>METHODS</b>Protein expression levels were assessed by western blot in the human uveal melanoma 92-1 cells after treatment with ionizing radiation. Depletion of p21 was carried out by employing the siRNA technique. Cell cycle distribution was determined by flow cytometry combined with histone H3 phosphorylation at Ser28, an M-phase marker. Senescence was assessed by senescence- associated-β-galactosidase (SA-β-gal) staining combined with Ki67 staining, a cell proliferation marker.</p><p><b>RESULTS</b>Accompanying increased p21, the protein levels of G2/M transition genes declined significantly in 92-1 cells irradiated with 5 Gy of X-rays. Furthermore, these irradiated cells were blocked at the G2 phase followed by cellular senescence. Depletion of p21 rescued radiation-induced G2 arrest as demonstrated by the upregulation of G2/M transition kinases, as well as the high expression of histone H3 phosphorylated at Ser28. Knockdown of p21 resulted in entry into mitosis of irradiated 92-1 cells. However, cells with serious DNA damage failed to undergo cytokinesis, leading to the accumulation of multinucleated cells.</p><p><b>CONCLUSION</b>Our results indicated that p21 was responsible for the downregulation of G2/M transition regulatory proteins and the bypass of mitosis induced by irradiation. Downregulation of p21 by siRNA resulted in G2-arrested cells entering into mitosis with serious DNA damage. This is the first report on elucidating the role of p21 in the bypass of mitosis.</p>