• Progress in Medical Physics
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• v.22 no.2
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• pp.85-91
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• 2011

The energy spectra for electron beam of medical linear accelerator were calculated using a GEANT4 Medical Linac 2 example code. The incident electron mean energy were 6, 9, 12, 16, 20 MeV. This code was designed to calculate electron beam energy spectra according to material, thickness and location of electron scattering foil affecting electron beam characteristic. Lead, Copper, Aluminum and Gold were used for scattering foil. The energy distribution for electron and photon were analyzed by changing position of scattering foil in the head of linear accelerator. The effect of electron scattering foil on energy spectra which is basic data of simulation for medical linear accelerator were presented. The calculated results would be used in design of medical accelerator head.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.2
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• pp.150-154
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• 2020

We present a case of osteoradionecrosis treated with leukocyte- and platelet-rich fibrin (LPRF) and surgery and followed up with clinical and tomographic investigations. A 65-year-old woman presented with pain in the posterior region of the right palate. Her medical history included cardiovascular disease and squamous cell carcinoma in the anterior region of the floor of the mouth that had been treated with intensity-modulated radiation therapy. Measurements of isodose curves showed a full dosage of 6,462.6 cGy in the anterior mandibular region, whereas that in the posterior region on the right side of the maxilla reached 5,708.1 cGy. Osteotomy was performed using rotary instruments, and debridement and placement of two LPRF membranes were also carried out. New gum tissue with no bone exposure was noted 14 days postoperatively. Tissue repair was complete, and the patient had no further complaints. During a 39-month follow-up period, the oral mucosa remained intact, and the patient was rehabilitated with a new upper denture. Since there is no consensus regarding the best protocol to treat osteoradionecrosis, LPRF might be an interesting adjuvant to a surgical approach. The use of LPRF is simple and reduces operational costs, time of handling, probability of technical failure, and associated morbidities for patients with osteoradionecrosis.

• BMB Reports
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• v.51 no.10
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• pp.481-483
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• 2018

Glioblastoma (GBM) is the most common and aggressive form of human adult brain malignancy. The identification of the cell of origin harboring cancer-driver mutations is the fundamental issue for understanding the nature of GBM and developing the effective therapeutic target. It has been a long-term hypothesis that neural stem cells in the subventricular zone (SVZ) might be the origin-of-cells in human glioblastoma since they are known to have life-long proliferative activity and acquire somatic mutations. However, the cell of origin for GBM remains controversial due to lack of direct evidence thereof in human GBM. Our recent study using various sequencing techniques in triple matched samples such as tumor-free SVZ, tumor, and normal tissues from human patients identified the clonal relationship of driver mutations between GBM and tumor-free SVZ harboring neural stem cells (NSCs). Tumor-free SVZ tissue away from the tumor contained low-level GBM driver mutations (as low as 1% allelic frequency) that were found in the dominant clones in its matching tumors. Moreover, via single-cell sequencing and microdissection, it was discovered that astrocyte-like NSCs accumulating driver mutations evolved into GBM with clonal expansion. Furthermore, mutagenesis of cancer-driving genes of NSCs in mice leads to migration of mutant cells from SVZ to distant brain and development of high-grade glioma through the aberrant growth of oligodendrocyte precursor lineage. Altogether, the present study provides the first direct evidence that NSCs in human SVZ is the cell of origin that develops the driver mutations of GBM.

• Progress in Medical Physics
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• v.26 no.4
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• pp.229-233
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• 2015

We retrospectively reviewed lung cancer patients who were treated with stereotactic ablative radiotherapy (SABR). We investigated the value of response evaluation after treatment by measuring the volume change of tumors on serial chest computed tomography (CT) examinations. The study included 11 consecutive patients with early-stage (T1-T2aN0M0) non-small cell lung cancer (NSCLC) who were treated with SABR. The median dose of SABR was 6,000 cGy (range 5,000~6,400) in five fractions. Sequential follow-up was performed with chest CT scans. Median follow-up time was 28 months. Radiologic measurement was performed on 51 CT scans with a median of 3 CT scans per patient. The median time to partial response ($T_{PR}$) was 3 months and median time to complete remission ($T_{CR}$) was 5 months. Overall response rate was 90.9% (10/11). Five patients had complete remission, five had partial response, and one patient developed progressive disease without response. On follow-up, three patients (27.2%) developed progressive disease after treatment. We evaluated the the response after SABR. Our data also showed the timing of response after SABR.

• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.389-395
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• 2013

This study intended to investigate the optimum conditions for lumbar test that has the highest level of irradiation conditions among general test sites. To to this, the most widely used irradiation conditions in terms of statistics were set as standards; test groups applied with DMF were selected; tests groups suitable for clinical trials were selected by using suggested patient dose. Blind tests were conducted by 10 specialists and radiologists. The results suggested that under the optimum conditions, the radiation dose reduction of 2.09 mGy, 4.42 mGy and 3.65 mGy can be achieved in forward-backward test, lateral test and 4-direction test, respectively. There is a need of further studies on the optimization of irradiation conditions in accordance with the conditions of patients.

• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.282-289
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• 2018

Melanin is a pigment produced from tyrosine in melanocytes. Although melanin has a protective role against UVB radiation-induced damage, it is also associated with the development of melanoma and darker skin tone. Tyrosinase is a key enzyme in melanin synthesis, which regulates the rate-limiting step during conversion of tyrosine into DOPA and dopaquinone. To develop effective RNA interference therapeutics, we designed a melanin siRNA pool by applying multiple prediction programs to reduce human tyrosinase levels. First, 272 siRNAs passed the target accessibility evaluation using the RNAxs program. Then we selected 34 siRNA sequences with ${\Delta}G{\geq}-34.6kcal/mol$, i-Score value ${\geq}65$, and siRNA scales score ${\leq}30$. siRNAs were designed as 19-bp RNA duplexes with an asymmetric 3' overhang at the 3' end of the antisense strand. We tested if these siRNAs effectively reduced tyrosinase gene expression using qRT-PCR and found that 17 siRNA sequences were more effective than commercially available siRNA. Three siRNAs further tested showed an effective visual color change in MNT-1 human cells without cytotoxic effects, indicating these sequences are anti-melanogenic. Our study revealed that human tyrosinase siRNAs could be efficiently designed using multiple prediction algorithms.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.537-543
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• 2020

The elderly population in the modern society is growing rapidly due to advance medical technology and minimally invasive surgery. Therefore, as the tendency to use medical device is increasing, pathogenic infection is a concern. Therefore, the first aim of modern medicine is infection prevention in medical place. Recently, patient implants are increasing using 3D printing. Hydroxyapatite is used as a representative material. And, there haven't had currently absorbed dose standard for sterilization of hydroxyapatite discs. Escherichia coli and Streptococcus mutans contaminated on the surface of hydroxyapatite discs were irradiated at each absorbed dose of 0, 0.5, 1.0, 3.0, 5.0 kGy using Gamma-ray of cobalt and Electron-beam of linear accelerator. Then, the number of bacteria was measured in the sample by the decimal dilution method. After sterilization, a non-parametric testing method was performed to compare the survival of Escherichia coli and Streptococcus mutans. As a result, Escherichia coli was sterilized at 1 kGy or more and Streptococcus mutans at 3 kGy or more on absorbed dose. It is considered possible to perform sterilization at a lower value than the recommended absorbed dose of radiation sterilization.

• Journal of The Korean Dental Society of Anesthesiology
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• v.10 no.1
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• pp.20-26
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• 2010

This type of neuropathic pain(atypical odontalgia) is seen most often in middle-aged women or men after dentoalveolar operation. Atypical odontalgia probably is caused by deafferentation leading to intraneural changes in the medullary dorsal horn. Treatment of this problem is difficult, but some success has been reported in uncontrolled, open-labeled studies using high doses of tricyclic antidepressants. This is the management report of a patient case, that had a neuropathic atypical odontalgia recognized with the right maxillary lateral incisor. The patient was consulted to the Department of Pain Clinics, ENT & Neurology and diagnosed the adenoid cystic carcinoma on left cerebellum and right paranasal sinus with extension to the cavernous sinus. In spite of the osteoplastic craniotomy, neurosurgical mass removal and radiation therapy were done with chemotherapy, atypical odontalgia was continued. In addition to the consultation to Psychology, stress management and antidepressant medication were done and improved slowly.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.8
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• pp.3415-3418
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• 2014

Background: AKAP12 inhibits oncogenic proliferation, invasion, chemotaxis and neovascularization. Bcl-2 and p53 are two important apoptotic markers that play roles in apoptotic processes. It has been found that AKAP12 blocks the cell cycle and induces apoptosis in fibrosarcoma cells. In our study we assessed the relationship of AKAP12 with apoptotic markers, Bcl-2 and p53. Materials and Methods: Our study included 45 cases that were histopathologically diagnosed with colorectal carcinoma from the tissue samples acquired by surgical resection. AKAP 12, Bcl-2, and p53 expression was examined by immunohistochemistry. Results: A total of 45 colorectal adenocarcinoma patients - 17 (37.8%) females and 28 (62.2%) males - were included in this study. AKAP12 expression was found to be negative in 8 patients (17.8%), and positive in 37 patients (82.2%). Bcl-2 was found positive in 6 patients (13.3%) and p53 in 29 patients (55.6%). AKAP12 expression had no significant relation with Bcl-2 and p53 expression (p:0.939, p:0.079, respectively). Conclusions: Although various studies have pointed to apoptotic activity of AKAP12, the literature is limited regarding relations with p53 or Bcl-2 expression. In the present study, we found no relation in colorectal carcinomas.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.5
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• pp.2061-2067
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• 2014

Background: It has been demonstrated that neutrophil:lymphocyte (NLR) and platelet:lymphocyte (PLR) ratios are associated with prognosis in cancer patients. The aim of this study was to investigate whether pretreatment white blood cell (WBC), neutrophil, lymphocyte, monocyte, platelet, basophil and eosinophil counts, LDH level, NLR and PLR are associated with prognosis in patients with malignant pleural mesothelioma (MPM). Materials and Methods: We retrospectively reviewed files of 50 patients who were managed with a diagnosis of MPM between 2005 and 2010. Demographic and clinical characteristics, treatments, response to treatment and prognostic factors were evaluated, along with relationships between pretreatment blood parameters and prognosis. Results: Overall, 38 men and 12 women were included to the study. Mean age was $61.5{\pm}9.4$ years (range: 39-83 years). There was advanced disease in 86% (n=43) and the histological type was epithelial mesothelioma in the majority (82%). Of the cases, 17 (34%) received radiotherapy, while 42 cases underwent first- and second-line chemotherapy, with cisplatin plus pemetrexed as the most commonly used regimen. In the assessment after therapy, it was found that there was complete response in 4 cases (8%), partial response in 10 cases (20%), stable disease in 17 cases (34%) and progression in 19 cases (38%). Median follow-up was 10 months (range: 10 day-30 months). Median overall survival was found to be 20.7 months while median progression-free survival as 10 months. In univariate and multivariate analyses, it was found that factors significantly affecting overall survival included stage (p=0.030), response to treatment (p=0.026) and monocyte count (p=0.004), while factors affecting disease-free survival included NLR (p=0.018), response to treatment (p=0.001), and PLR score (p=0.003). Conclusions: Overall and disease-free survival was found to be better in cases with a WBC count<8.000, platelet count<300,000, and low NLR and PLR scores in malignant pleural mesothelioma.