• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.212-217
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• 2007

As a preliminary study for the development of electrical stimulation strategy of artificial retina, we set up a method fur the reconstruction of input intensity variation from retinal ganglion cell(RGC) responses. In order to estimate light intensity variation, we used an optimal linear filter trained from given stimulus intensity variation and multiple single unit spike trains from RGCs. By applying ON/OFF stimulation(ON duration: 2 sec, OFF duration: 5 sec) repetitively, we identified three functional types of ganglion cells according to when they respond to the ON/OFF stimulus actively: ON cell, OFF cell, and ON-OFF cell. Experiments were also performed using a Gaussian random stimulus and a binary random stimulus. The input intensity was updated once every 90 msec(i. e. 11 Hz) to present the stimulus. The result of reconstructing 11 Hz Gaussian and binary random stimulus was not satisfactory and showed low correlation between the original and reconstructed stimulus. In the case of ON/OFF stimulus in which temporal variation is slow, successful reconstruction was achieved and the correlation coefficient was as high as 0.8.

• Progress in Medical Physics
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• v.18 no.1
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• pp.20-26
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• 2007

It is expected that synaptic construction and electrical characteristics In degenerate retina might be different from those In normal retina. Therefore, we analyzed the retinal waveform recorded with multielectrode array in normal and degenerate retina using principal component analysis (PCA) and Independent component analysis (ICA) and compared the results. PCA Is a well established method for retinal waveform while ICA has not tried for retinal waveform analysis. We programmed ICA toolbox for spatiotemporal analysis of retinal waveform. In normal mouse, the MEA spatial map shows a single hot spot perfectly matched with PCA-derived ON or OFF ganglion cell response. However In rd/rd mouse, the MEA spatial map shows numerous hot and cold spots whose underlying interactions and mechanisms need further Investigation for better understanding.

• Advances in pediatric surgery
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• v.19 no.2
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• pp.122-129
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• 2013

Immature ganglion cell (IGC) is known for its relationship with intestinal motility and its impact on postoperative functional outcomes of Hirschsprung's disease (HD). There are few studies on the relationship between intestinal dysmotility and IGC in HD patients. 67 patients pathologically diagnosed with HD and who received definitive operation in Seoul National University Children's Hospital from 2010 to 2011 were included. 10 patients were excluded due to inadequate immunohistochemical staining results. The proximal end of resected ganglionic segment was evaluated with immunohistochemistry examination with MAP-2, a marker of ganglionic cells and bcl-2, a marker of IGCs The median age at operation was 155 (15-4678) day-old. 55 (96.5%) patients positive for bcl-2, were regarded as having IGC, and 2 (3.5%) patients positive for MAP-2 but negative for bcl-2, were regarded as having only mature ganglion cells. In the bcl-2 positive group, there were 7 patients (12.7%) with constipation, 15 patients (27.3%) with soiling, 3 patients (5.5%) with perianal excoriation and 6 patients (10.9%) with medication use. In bcl-2 negative group, intestinal dysmotility was not seen. There was no statistical significance in the two groups. Considering that HD is diagnosed at a young age, the rate of IGC present is very high and it might be inappropriate to relate IGC to functional outcome at young ages.

• Korean Journal of Veterinary Research
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• v.29 no.1
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• pp.1-6
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• 1989

The number and distribution of the retinal ganglion cells in the 2 years old Korean native cattle was determined from whole fiat mounted preparation stained with methylene blue and thionin. The results were summarized as follows. 1. The total number of retinal ganglion cells was estimated to be 3,085,200 in the bovine retina ranging from $2,214mm^2$ in total area. 2. Visual streak was recognized at the area 2.5mm superior to the optic disc and ganglion cell density drops off rapidly to the directions superior to and inferior to the visual streak. 3. Area centralis ($6,800cells/mm^2$) was located at the area 10mm temporally from the point of 3mm superior to the optic disc. 4. The number of ${\alpha}-type$ ganglion cells (above $15{\mu}$) was 57,000 in the bovine retina and ${\alpha}-type$ ganglion cells constituted 18.5% of the total cells. 5. The relative frequency of ${\alpha}-type$ ganglion cells was higher in the peripheral regions than in the visual streak, especially higher in the superior-temporal quadrant than in other region of the bovine retina.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.12 no.2
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• pp.194-198
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• 2009

Purpose: Severe abdominal distension is not uncommon symptom in the neonate. Two major causes of this symptom are benign transient intestinal ileus (BTII) and Hirschsprung`s disease (HD). But it is difficult to differentiate BTII from HD based on the symptoms and simple abdominal x-ray findings. The aim of this retrospective study was to assess the clinical aspects and diagnostic tests differencing two diseases. Methods: From August 2004 to March 2009, nineteen patients with severe abdominal distension, who underwent barium enema, anorectal manometry, and rectal suction biopsy (triple tests) due to a suspicion of HD, were enrolled. A comparison of clinical data associated with BTII and HD based on the clinical features and results of triple tests. Results: The age of onset of symptom was between 2 and 6 weeks in BTII and within 3 weeks in HD. On the barium enema, transitional zone revealed in 6 (50%) patients in BTII and 4 (57.1%) in HD. On anorectal manometry, the anorectal inhibitory reflex was present in 11 (91.7%) patients in BTII and 1 (14.3%) in HD. On rectal suction biopsy, ganglion cell was present in 9 (75%) patients in BTII and 0 (0%) in HD. Abdominal distension was improved within 3 months of life in all cases of BTII. Conclusion: We think that anorectal manometry may be more simple and useful diagnostic method than barium enema and rectal suction biopsy for differential diagnosis of transient intestinal ileus and Hirschsprung's disease.

• Clinical and Experimental Pediatrics
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• v.45 no.8
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• pp.1028-1032
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• 2002

Subcutaneous pannicultis-like T cell lymphoma is a rare cutaneous T cell lymphoma. It presents with multiple subcutaneous nodules or plaques involving the extremities or trunk, and with constitutional symptoms that include fever, malaise, fatigue, myalgia, chills and weight loss. Histologically, the lesions of this disease are reminiscent of panniculitis and are composed of a mixture of small and large atypical lymphoid cells infiltrating between adipocytes. The optimal treatment for this disease is undefined and prognosis of this disease is poor, even when treated with multiagent chemotherapy regimens considered optimal for agressive lymphoma of other types. Poor prognosis factors include clinical features such as anemia, leukocytopenia, hepatosplenomegaly, lymphadenopathy and coagulopathy, which are suggestive of hemophagocytosis. Much of the mortality of this disease is due not to disseminated lymphoma with organ failure, but rather to complications of the cytopenias associated with the hemophagocytic syndrome. We report a case of subcutaneous panniculitis-like T cell lymphoma in a 12 year-old boy who presented with initial complaints of fever and multiple subcutaneous nodules, and briefly review the related literature.

• Journal of Chest Surgery
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• v.30 no.1
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• pp.55-60
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• 1997

We reviewed 40 cases of primary mediastinal tumors which were operated on at Seoul Paik Hospital from September, 1987 to December, 1995. Of these, 18 were male and 22 were female. The patient ranged in age from 4 years to 68 years with a mean age of 34.1 years. The most common symptoms included chest pain(12.5%), cough(12.5%), dyspnea(7.5%). and palpable neck mass(7.5%), and symptoms were absent at the time of diagnosis in 37.5% of cases. Chest roentgenography and computed tomography(CT) were performed in all patients, and magnetic resonance imaging(MRI) in 5 patients, and transthoracic needle aspiration (TTNA) performed In 22 patients. The sensitivity of TTNA was 72.7%(16 of 22 patients). The lesion was located 60% in the anterosuperior mediastinum, 35% in the posterior mediastinum, and 5% in the middle mediastinum. The primary tumors included thymic neoplasms(11 cases), germ cell tumors(7 cases), neurogenic tumors(10 cases) and a miscellaneous group. The malignant tumors(12.5%) were invasive thymoma(3 cases), spindle cell sarcoma(1 case), and non-Hodgkin's Iymphoma(1 case). A complete excision was done in all 35 benign tumors and 3 malignant tumors. There was no operative mortality, and postoperative complications occurred in 3 cases.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.100-107
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• 1999

Purpose: This is to evaluate the acute complication, resection rate, and tumor down-staging after pre-operative concurrent chemoradiotherapy for stage IIIA (N2) non-small cell lung cancer. Materials and Methods Fifteen patients with non-small cell lung cancer were enrolled in this study from May 1997 to June 1998 in Samsung Medical Center. The median age of the patients was 61 (range, 45~67) years and male to female ratio was 12:3. Pathologic types were squamous cell carcinoma (11) and adenocarcinoma (4). Pre-operative clinical tumor stages were cT1 in 2 patients, cT2 in T2, and cT3 in 1 and all were N2. Ten patients were proved to be N2 with mediastinoscopic biopsy and five had clinically evident mediastinal Iymph node metastases on the chest CT scans. Pre-operative radiation therapy field included the primary tumor, the ipsilateral hilum, and the mediastinum. Total radiation dose was 45 Gy over 5 weeks with daily dose of 1.8 Gy. Pre-operative concurrent chemotherapy consisted of two cycles of intravenous cis-Platin (100 mg/m$^{2}$) on day 1 and oral Etoposide (50 mg/m$^{2}$/day) on days 1 through 14 with 4 weeks' interval. Surgery was followed after the pre-operative re-evaluation including chest CT scan in 3 weeks of the completion of the concurrent chemoradiotherapy if there was no evidence of disease progression. Results : Full dose radiation therapy was administered to all the 15 patients. Planned two cycles of chemotherapy was completed in 11 patients and one cycle was given to four. One treatment related death of acute respiratory distress syndrome occurred In 15 days of surgery. Hospital admission was required in three patients including one with radiation pneumonitis and two with neutropenic fever. Hematologic complications and other acute complications including esophagitis were tolerable. Resection rate was 92.3% (12/l3) in 13 patients excluding two patients who refused surgery. Pleural seeding was found in one patient after thoracotomy and tumor resection was not feasible. Post-operative tumor stagings were pT0 in 3 patients, pTl in 6, and pT2 in 3. Lymph node status findings were pN0 in 8 patients, pN1 in 1, and pN2 in 3. Pathologic tumor down-staging was 61.5% (8/13) including complete response in three patients ($23.7%). Tumor stage was unchanged in four patients (30.8%) and progression was in one (7.7%). Conclusions : Pre-operative concurrent chemoradiotherapy for Stage IIIA (N2) non-small cell lung cancer demonstrated satisfactory results with no increased severe acute complications. This treatment shceme deserves more patinet accrual with long-term follow-up.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.85-91
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• 2000

Purpose : The aim of this study is to look for the possible efficacy of postoperative external irradiation for incompletely resected meningiomas. Methods and Materials : From August 198: to January 1997, forty-four patients with intracranial meningioma were treated by postoperative external irradiation. Of the 44 meningiomas, 18 transitional, 13 meningotheliomatous, 6 hemangiopericytic, 4 atypical, 2 fibroblastic and 1 malignant meningioma were identified. We classified all patients into two groups by the histology. The benign group was consisted of the meningotheliomatous, transitional and fibroblastic types. The malignant group was consisted of the atypical, hemangiopericytic and malignat types. In the means of surgery, 37 patients were resected incompletely and 7 patients were managed by biopsy only. After surgery, all patients were received postoperative external irradiation. Radiotherapy was deliverd using Co-60 or 4 MV photon beam to a total dose of 50 to 65 Gy (mean dose 57.4 Gy) with a 1.8 to 2 Gy per fraction. The median follow-up was 48 months (range : 21 $\~$ 101 months). Multivariate analysis of the Influence by age, sex, location, histology and radiation dose on local control has been done using Cox's proportional hazard model. Results : 5-year local control rate was 93.8$\%$ for the benign histology and 51.8$\%$ for the malignant histology (p=0.0110) and overall local control rate at 5 years was 87.4$\%$. The analysis of the prognostic factors, such as age, sex, location, and radiation dose were not significant except for the histology. Conclusion : Adjuvant postoperative external irradiation appears to be significantly improved local control in the patients with incompletely resected meningiomas.

• Radiation Oncology Journal
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• v.15 no.4
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• pp.379-385
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• 1997

Purpose : Ovarian dysgerminoma is a highly radiosensitive malignant tumor occurring in young age group. The conventional treatment was total abdominal hysterectomy and bilateral salpingo-oophorectomy followed by radiotherapy. We retrospectively analyzed the treatment results of Patients who had received radiotherapy in the era before chemotherapy was widely used. Material and Method : Twenty two patients with ovarian dysgerminoma were treated at the Department of Therapeutic Radiology, Seoul National University Hospital between August, 1980 and May, 1991. Four patients were excluded from this study, because three patients received incomplete treatment and one received combined chemotherapy. Sixteen patients received postoperative radiotherapy and two patients had radical radiotherapy as tumor was unresectable. Median follow-up period was 99 months (range, 51-178) Median age was 22 years (range, 11-42). Among the postoperatively treated patients, three Patients were in stage IA, eight in stage IC, two in stage II, and three in stage III. One patient had Turner's syndrome. Radiotherapy was performed with high energy photon (telecobalt unit or linear accelerator, either 6MV or 10MV), The radiation dose to the whole abdomen was 1950-2100cGy (median, 2000) and 1050-2520cGy was added to the whole pelvis, the total dose to the whole pelvis was 3000-4500cGy (median, 3500). Prophylactic Paraaortic area irradiation was done in six Patients (dose range, 900-1500cGy). One patient who had positive Paraaortic node, received radiation dose of 1620cGy, followed by additional 900cGy to the gross mass with shrinking field. Total dose to the paraaortic node was 4470cGy. Six patients, including one who had paraaortic node metastasis, received Prophylactic irradiation to mediastinum and supraclavicular area (2520cGy). Of the two patients with unresectable tumors who received radical radiotherapy, one was in stage III and the other was in stage IV with left supraclavicular lymph node metastasis. The stage III patient received radiation to the whole abdomen (2000cGy), followed by boost to whole pelvis (2070cGy) and paraaortic area (2450cGy). Stage IV patient received radiation to the whole abdomen (2000cGy), followed by radiation to the whole pelvis and paraaortic area (2400cGy), mediastinum (2520cGy) , and left supraclavicular area (3550cGy) .Results : The 5 year local control rate was $100\%$ in patients who received postoperative adiuvant radiotherapy after total abdominal hysterectomy and bilateral salpingo-oophorectomy. Only one patient in stage III who did not receive prophylactic irradiation to mediastinum developed mediastinal metastasis. but was salvaged by chemotherapy. So. the 5 year overall survival rate uras also $100\%$. Two patients who received radiation only, are alive without disease at 112 and 155 months. Conclusion : Postoperntive adjuvant radiotherapy as well as radical radiotherapy in unresectable ovarian dysgerminoma was very effective. aut chemotherapy is also an effective treatment modality We now recomrneifd chemotherapy for Patients who need to save their ovarian functien and reserve radiotherapv fov chemo-resistant tumor or recurrence alter che motherapy.