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Seung-Ki Kim, Kyu-Chang Wang, Byung-Kyu Cho, Hyun-Tai Chung, Young-Yim Kim, Su-Young Lim, Choon-Taek Lee and Hyun Jib Kim

Object. Multiple gene replacements have been examined as a potential treatment modality for malignant gliomas. Nevertheless, no reports are available that detail the synergy, additivity, or antagonism of multiple genes. The aim of this study was to assess the interaction between p53 and p16 genes in the growth of glioma cell lines.

Methods. The human glioma cell lines U87MG and U373MG were transduced using an adenoviral vector with Ad-p53, Ad-p16, or both. Western blotting was performed to determine the expression of the protein products of the transduced p53 and p16 genes. To establish whether the combination of Ad-p53 and Ad-p16 would be beneficial, the effects of gene combinations at the median inhibitory concentration level were analyzed using the isobologram method. Annexin assays and cell cycle analyses were performed on the transduced cells. Western blotting demonstrated the expression of p53 and p16 in transduced cells. Simultaneous exposure to Ad-p53 and Ad-p16 produced additive effects in both glioma cell lines. Experimental data points in U373MG lay near the Mode I line, indicating that the vectors had a different mode of action. The restoration of normal p53-encoded protein in the mutant cell lines induced apoptosis, whereas in the wild-type p53 cell lines, the overexpression of wild-type p53 resulted in a moderate degree of apoptosis and G1 arrest. Furthermore, Ad-p16 induced more marked G1 arrest than Ad-p53 in cells with wild-type p53.

Conclusions. The results show that interaction between Ad-p53 and Ad-p16 is additive, regardless of p53 gene status.

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Jin Sup Yeom, Moon Sang Chung, Choon-Ki Lee, Yeongho Kim, Namkug Kim and Jae Bum Lee

✓ The quality of a computerized tomography (CT) scan is significantly reduced by metal artifact caused by a pedicle screw system. The purpose of this study was to develop a method of facilitating the evaluation of pedicle screw position on CT scans obtained after screw insertion.

The authors developed an algorithm to process spiral CT scans in a personal computer. This uses a digital image enhancement technique, the curve change-based intensity transformation algorithm. This method can generate a clear image of the screw outlines while reducing metal artifact. The resulting images are displayed in arbitrary planes as well as in axial, coronal, and sagittal planes, to support better the evaluation of pedicle screw position.

The algorithm was tested using CT scans obtained in 37 patients in whom 186 pedicle screws had been placed. There were five types of screw systems, all of which were made of titanium alloys. In all cases algorithm-based determination of screw position became more convenient and more accurate than when using the conventional bone window setting. In addition, it provided better soft-tissue visualization than the bone window.

The software, by displaying clear outlines of screws and decreasing metal artifact, as well as by reconstructing the images in arbitrary planes, was more helpful in identifying the position of pedicle screws than the conventional bone window setting.

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Kyung-Ho Park, Jaeho Lee, Chul-Gyu Yoo, Young Whan Kim, Sung Koo Han, Young-Soo Shim, Seung-Ki Kim, Kyu-Chang Wang, Byung-Kyu Cho and Choon-Taek Lee

Object. Malignant glioma could be an ideal candidate for local gene therapy because its invasion is local and it has little metastatic potential. A low expression level and high degradation activity of p27 are known to constitute an independent poor prognostic factor in patients with malignant glioma. In this study, the authors investigated the roles of wild-type p27 and mutant p27 on the treatment of malignant glioma.

Methods. The authors used two adenoviruses: one expressed wild-type p27 (ad-p27wt) and the other, containing a mutation at the major metabolic site, expressed mutant p27 (ad-p27mt). The antitumor effects of the two adenoviruses were compared with respect to cell growth arrest, cell cycle alteration, apoptosis induction, and in vitro tumorigenicity in three glioblastoma mutiforme (GBM) cell lines and in a primary GBM cell line. Transduction with ad-p27wt or ad-p27mt induced the production of p27 and the dephosphorylation of pRB. The protein level of mutant p27 was significantly higher than that of wild-type p27. The ad-p27wt induced cell cycle arrest at the G1—S transition point, whereas the ad-p27mt induced arrest at the G2—M point. Both ad-p27wt and ad-p27mt induced a growth-inhibiting effect, apoptosis, and suppression of in vitro tumorigenicity; however, ad-p27mt displayed a stronger antitumor effect than ad-p27wt in brain tumor cell lines.

Conclusions. Gene therapy involving p27, especially mutant p27, has the potential to become a novel and powerful therapy for malignant glioma.

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Jin S. Yeom, Kyeong Hwan Kim, Soon Woo Hong, Kun-Woo Park, Bong-Soon Chang, Choon-Ki Lee and Jacob M. Buchowski

✓ Surgical treatment of intraforaminal disc herniations at the L5–S1 level is technically demanding. The 2 most commonly used procedures involve either a medial or lateral ipsilateral approach and often require a partial or even complete facet resection, which may in turn result in vertebral instability and/or back pain, as well as, in some cases, a fusion or stabilization procedure. In this report, the authors present a new minimally invasive technique for the treatment of L5–S1 intraforaminal disc herniations. Using this technique, which involves tubular retractors and an operative microscope to approach the neural foramen from the contralateral side, the authors could easily visualize and remove the herniated disc material and perform a thorough microdiscectomy with minimal resection of osseous and ligamentous structures. To illustrate this new minimally invasive technique for the treatment of intraforaminal disc herniations at L5–S1, they describe the cases of 2 patients who underwent the procedure and in whom successful results were achieved.

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Chang Ju Hwang, Choon-Ki Lee, Bong-Soon Chang, Min-Seok Kim, Jin S. Yeom and Jin-Man Choi

Object

The aim of this study was to evaluate after more than 5 years the outcome of surgical treatment for flexible idiopathic scoliosis using skipped pedicle screw fixation.

Methods

For patients with spine curves < 90° and flexibility > 20%, pedicle screws had been inserted into every other segment on the corrective side and 2–4 screws per curve had been inserted on the supportive side. The authors analyzed the results in 57 patients, including the correction rate of coronal curvature and rotational deformity, correction loss, sagittal balance, complications, blood loss, operation time, and implant costs.

Results

The mean Cobb angle was 54° preoperatively and 17° immediately after surgery (69% correction). At the last follow-up, the mean Cobb angle was 18° (2% correction loss). Rotation of the apical vertebra was corrected by 50% on average and showed only a 6% correction loss at the last follow-up. None of the patients had problems in maintaining sagittal balance. An adding-on phenomenon was detected in 4 patients (7%). Twelve of 14 patients with coronal decompensation showed improvement after surgery, whereas postoperative decompensation developed in 3 patients. Four patients had implant failures, and 4 had postoperative infections. The mean blood loss during surgery was 832 ml, and the mean operation time was 167 minutes. Compared with conventional methods, the authors' method used up to 48% fewer screws.

Conclusions

Skipped pedicle screw fixation of flexible idiopathic scoliosis showed satisfactory results. This method has several advantages, including reduced blood loss, shorter operation time, and reduced cost.

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Bo-Gun Suh, Mary Ruth A. Padua, K. Daniel Riew, Ho-Joong Kim, Bong-Soon Chang, Choon-Ki Lee and Jin S. Yeom

Object

The authors introduce a simple technique and tool to facilitate reduction of atlantoaxial subluxation during posterior segmental screw fixation.

Methods

Two types of reduction tool have been designed: T-type and L-type. A T-shaped levering tool was used when a pedicle or pars screw was used for C-2, and an L-shaped tool was used when a laminar screw was used for C-2. Twenty-two patients who underwent atlantoaxial segmental screw fixation and fusion for the treatment of anteroposterior instability or subluxation, using either of these new types of reduction tool, were enrolled. Demographic, clinical, and surgical data, which had been prospectively collected in a database, were analyzed. The atlantodens interval was measured on lateral radiographs, and the space available for the spinal cord was measured on CT scans.

Results

The authors could attain reduction of the atlantoaxial subluxation without difficulty using either type of tool. The preoperative atlantodens interval ranged from −16.9 to 10.9 mm in a neutral position, and the postoperative interval ranged from −2.8 to 3.0 mm, with negative values due to extension-type or mixed-type instability. The mean space available for the spinal cord significantly increased, from 9.5 mm preoperatively to 15.4 mm postoperatively (p < 0.001).

Conclusions

This technique allowed for controlled manipulation and reduction of the atlantoaxial subluxation without difficulty.

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Peng-Yuan Chang, Jau-Ching Wu, Wen-Cheng Huang, Tsung-Hsi Tu and Henrich Cheng

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Kyeong Hwan Kim, Dong Bong Lee, Ho-Joong Kim, K. Daniel Riew, Boo Seop Kim, Bong-Soon Chang, Choon-Ki Lee and Jin S. Yeom

Combined anterior and posterior surgery is frequently chosen for the treatment of prior, severe C1–2 dislocations that occurred during early childhood because of the difficulty in achieving reduction and satisfactory decompression. The authors treated a prior, severe C1–2 dislocation that was causing progressive quadriparesis. The patient was a 14-year-old boy who had suffered a C1–2 fracture-dislocation at 3 years of age and had been treated with a Minerva body jacket cast. The treatment involved posterior C1–2 segmental screw fixation, without direct bone decompression or additional surgery. Satisfactory neural decompression was achieved with the techniques used, and complete bone union was confirmed. The patient showed satisfactory neurological recovery at the 5-year follow-up assessment.