Hong-Moon Sohn

Determination of Distal Fusion Level With Segmental Pedicle Screw Fixation in Single Thoracic Idiopathic Scoliosis

Study Design. A retrospective study was conducted. Objective. To determine the exact distal fusion level in the treatment of single thoracic idiopathic scoliosis (King Types 3 and 4) with segmental pedicle screw fixation. Summary of Background Data. Pedicle screw fixation effectively shortens the distal fusion extent by improved three-dimensional deformity correction. However, the selection of distal fusion extent remains controversial in single thoracic idiopathic scoliosis. Methods. This study analyzed 42 patients with single thoracic adolescent idiopathic scoliosis (32 King 3 patients and 10 King 4 patients) who underwent segmental pedicle screw fixation and had a minimum follow-up period of 2 years (range, 2–6 years). The patients were grouped according to the distal fusion level with reference to the standing neutral rotated vertebra (NV) for comparison of deformity correction and spinal balance using standing radiographs. Failure to restore an adequate trunk balance and progression or extension of the primary curve (adding on) was considered unsatisfactory. Results. Preoperative 50° ± 11° of thoracic deformity was corrected to 13° ± 5°, for a curve correction of 74%. Preoperative 23° ± 7° of lumbar deformity was corrected to 2° ± 8°, for a curve correction of 93%. Curve correction was not significantly affected by King type or distal fusion level (P > 0.05). Postoperative unsatisfactory results were obtained in 14 patients. When the preoperative NV was the same or one level distal to end vertebra (EV), fusion down to NV was satisfactory (14/14). When the preoperative NV was more than two levels distal to EV, fusion down to one level shorter than NV (NV−1) also was satisfactory (9/9). However, when fusion down to NV−2 or shorter was performed, the chances of adding on were higher (14/19;P < 0.01). Preoperative 17° ± 8° of thoracic kyphosis was improved to 24° ± 7°. Conclusions. In single thoracic idiopathic scoliosis, NV is an important factor for the determination of fusion level. When preoperative NV and EV show no more than two-level gap differences, the curve should be fused down to NV. When the gap is more than two levels, fusion down to NV−1 is satisfactory, saving one or two motion segments, as compared with fusion extending to the stable vertebra.

Effects of light‐emitting diode irradiation on RANKL‐induced osteoclastogenesis

Bone homeostasis is maintained by a balance between osteoblastic bone formation and osteoclastic bone resorption, where intracellular reactive oxygen species (ROS) are crucial mediators of osteoclastogenesis. Recently, low‐level light therapy (LLLT), a form of laser medicine used in various clinical fields, was shown to alleviate oxidative stress by scavenging intracellular ROS. The present study aimed to investigate the impact of 635 nm irradiation from a light‐emitting diode (LED) on osteoclastogenesis from receptor activator of nuclear factor kappa‐B (NF‐κB) ligand (RANKL)‐stimulated mouse bone marrow‐derived macrophages (BMMs).

Effect of CD133 overexpression on the epithelial-to-mesenchymal transition in oral cancer cell lines

Oral squamous cell carcinoma (OSCC) is one of the most common cancers in the world. In OSCC, CD133 promotes tumor invasion and metastasis by inducing the epithelial-to-mesenchymal transition (EMT). A small subset of cancer cells known as cancer stem cells (CSCs) are thought to give rise to differentiated tumor cells and to predict tumor recurrence and metastases, i.e., CSCs may be metastatic precursors. In this study, we show that ectopic overexpression of CD133 in OSCC cell lines KB, YD9, and YD10B cells significantly promotes the EMT and acquisition of stemness properties. CSC properties were analyzed by colony-formation assay and measurement of OCT4, SOX2, and NANOG expression, and the EMT was monitored by cell migration, a cell invasion assay, and analysis of E-cadherin, N-cadherin, and vimentin expression. CD133 overexpression led to formation of irregular spheroid colonies consistent with a stem cell phenotype and increased the expression of OCT4, SOX2, NANOG, N-cadherin, and vimentin. Taken together, these findings show that elevated levels of CD133 lead to OSCC invasiveness and metastasis, associated with the upregulation of EMT and stemness markers.

Biological Effects of the Herbal Plant-Derived Phytoestrogen Bavachin in Primary Rat Chondrocytes

The aim of this study was to examine the anabolic and anticatabolic functions of bavachin in primary rat chondrocytes. With bavachin treatment, chondrocytes survived for 21 d without cell proliferation, and the proteoglycan content and extracellular matrix increased. Short-term monolayer culture of chondrocytes showed that gene induction of both aggrecan and collagen type II, major extracellular matrix components, was significantly upregulated by bavachin. The expression and activities of cartilage-degrading enzymes such as matrix metalloproteinases and a disintegrin and metalloproteinase with thrombospondin motifs were inhibited significantly by bavachin, while tissue inhibitors of metalloprotease were significantly upregulated. Bavachin inhibits the expression of inducible nitric oxide synthase, a representative catabolic factor, and downregulated the expression of nitric oxide, cyclooxygenase-2, and prostaglandin E2 in a dose-dependent manner in chondrocytes. Our results suggest that the bavachin has anabolic and potent anticatabolic biological effects on chondrocytes, which may have considerable promise in treating articular cartilage degeneration in the future.

Radiologic Evaluation of Degeneration in Isthmic and Degenerative Spondylolisthesis

Study Design A cross-sectional imaging study. Purpose The objective was to assess the degree of degeneration and the associated factors through imaging studies of the lesion segment and the adjacent superior and inferior segments of isthmic and degenerative spondylolisthesis. Overview of Literature Few articles existed for degeneration and related factors in isthmic and degenerative spondylolisthesis. Methods The subjects were 95 patients diagnosed with spondylolisthesis. Simple plain radiographs including flexion and extension and magnetic resonance imaging were used to investigate the degree of translation, disc degeneration, high intensity zone (HIZ) lesion, Schmorls node (SN) and Modic changes. Results Advanced disc degeneration, grade 5, was shown to be significant in the index segment of the isthmic type (p=0.034). Overall, type 2 Modic change was most common in both groups and also, it was observed more in the isthmus group, specifically, the index segment compared to the degenerative group (p=0.03). For the SN, compared to the degenerative type, the isthmus type had a significantly high occurrence in the index segment (p=0.04). For the HIZ lesions, the isthmus type had a higher occurrence than the degenerative type, especially in the upper segment (p=0.03). Conclusions Most advanced disc degeneration, fifth degree, SN and Modic change occurred more frequently in the lesions of the isthmus type. HIZ lesions were observed more in the isthmus type, especially in the segment superior to the lesion.

Ectopic overexpression of CD133 in HNSCC makes it resistant to commonly used chemotherapeutics.

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers in the world. Resistance to cytotoxic chemotherapy is a major cause of mortality in patients with HNSCC. A small subset of cancer cells called cancer stem cells (CSCs) may be key contributors to drug resistance and tumor recurrence in HNSCC. The aim of this study was to determine whether CD133, which maintains properties of CSCs, promotes chemoresistance by arresting cell cycle transition and reducing apoptosis in HNSCC cells. CD133 overexpression was examined in KB cells, and colony forming and aldehyde dehydrogenase activity assays were performed. To investigate the role of CD133 in chemoresistance, cell death was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Diff-Quick, flow cytometry, and western blot of apoptosis-related protein expression in fluorouracil (5-FU)- or cisplatin-treated cells. In addition, microarray and related protein expression assessments were performed to investigate the mechanism of chemoresistance against 5-FU and cisplatin in KB cells. Moreover, chemoresistance against 5-FU or cisplatin in a KB-inoculated mouse model was analyzed by hematoxylin and eosin staining, immunohistochemical study of CD133, and immunofluorescence of tumor tissue. In this study, we demonstrate that ectopic overexpression of CD133 significantly promotes properties of stemness in KB cell lines. Furthermore, CD133 promotes chemoresistance by arresting transition of the cell cycle and reducing apoptosis, which results in inhibition of tumor growth in 5-FU- or cisplatin-injected mouse tumor model. Taken together, our findings show that elevated levels of CD133 lead to HNSCC chemoresistance through increased stemness and cell cycle arrest.

Real-time in vivo imaging of metastatic bone tumors with a targeted near-infrared fluorophore

Tumors of the prostate or breast are particularly likely to metastasize to the bone, and early diagnosis of metastatic bone tumors is important for designing an effective treatment strategy. Imaging modalities for the detection of bone metastasis are limited, and radiation-based techniques are commonly used. Here, we investigated the efficacy of selective near-infrared (NIR) fluorescence detection of metastatic bone tumors and its role in the detection of bone metastasis in prostate and breast cancer cell lines and in a xenograft mouse model. A targeted NIR fluorophore was used to monitor metastatic bone tumors using a NIR fluorescence imaging system in real time, enabling the diagnosis of bone metastasis in vivo by providing the location of the metastatic bone tumor. The NIR fluorescence imaging technique using targeted NIR contrast agents is a potential tool for the early diagnosis of bone tumors.

Cloning and expression of recombinant macrophage-colony stimulating factor - A progressive strategy for economical production

Macrophage-colony stimulating factor (M-CSF) has been reported to be required for the proliferation and differentiation of macrophages from hematopoietic progenitor cells. Recently, recombinant M-CSF (rM-CSF) became widely used as a biological research reagent in bone marrow stimulations, vaccine development, gene therapy approaches, and stem cell mobilization. rM-CSF is a glycoprotein that activates and enhances the differentiation and survival of macrophages, which play a key role in the osteoclastogenetic response. Here, we describe the construction of the gene encoding rM-CSF, its cloning, and expression in Escherichia coli, as well as the purification of rM-CSF protein, and its activity in a biological assay in mouse bone marrow cells. Our results show that the combination of experimental strategies employed to obtain recombinant rM-CSF can yield a biologically active protein, and may be useful when scaling-up production of other biologically similar proteins.