• The Korean Journal of Nuclear Medicine
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• v.34 no.1
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• pp.39-54
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• 2000

Purpose: Dipyridamole stress myocardial perfusion SPECT could predict prognosis, however, long-term follow-up showed change of hazard ratio in patients with suspected coronary artery disease. We investigated how long normal SPECT could predict the benign prognosis on the long-term follow-up. Materials and Methods: We followed up 1169 patients and divided these patients into groups in whom coronary angiography were performed and were not. Total cardiac event rate and hard event rate were predicted using clinical, angiographic and SPECT findings. Predictive values of normal and abnormal SPECT were examined using survival analysis with Mantel-Haenszel method, multivariate Cox proportional hazard model analysis and newly developed statistical method to test time-invariance of hazard rate and changing point of this rate. Results: Reversible perfusion decrease on myocardial perfusion SPECT predicted higher total cardiac event rate independently and further to angiographic findings. However, myocardial SPECT showed independent but not incremental prognostic values for hard event rate. Hazard ratio of normal perfusion SPECT was changed significantly (p<0.001) and the changing point of hazard rate was 4.4 years of follows up. However, the ratio of abnormal SPECT was not. Conclusion: Dipyridamole stress myocardial perfusion SPECT provided independent prognostic information in patients with known and suspected coronary artery disease. Normal perfusion SPECT predicted least event rate for 4.4 years.

• Journal of Chest Surgery
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• v.35 no.7
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• pp.517-522
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• 2002

Background: Congenital heart surgery may lead to myocardial swelling and hemodynamic instability. Delayed sternal closure may be beneficial in this setting. The purpose of this study was to assess mortality and mediastinal infection rate associated with delayed sternal closure after congenital heart surgery and to evaluate the risk factors which affect mortality and mediastinal infection rate. Material and Method: We retrospectively reviewed 40 patients who underwent delayed sternal closure after repair of congenital heart disease at Yonsei Cardiovascular Hospital, from January 1994 to May 2001. In these patients, we assessed the mortality and mediastinal infection rate, and evaluated their risk factors including operation time, bypass time, aortic cross clamp time, duration to sternal closure and postoperative artificial ventilation time. Mediastinal infection was defined to have positive culture in mediastinum. Result: Hemodynamic instability was the most common indication for delayed sternal closure(n=36) and other indications included postoperative bleeding(n=2) and conduit compression(n=2). The median age at operation was $14.4{\pm}33.4$months old(range, 2days-12years). The patients with postoperative bleeding and conduit compression were much older than the others. The sternum was left open for $4.5{\pm}3.4$ days(range, 1-20days). Overall mortality was 25%(10/40) and mediastinal infection occured in 24.3%(9/37) (3 patients were excluded in mediastinal infection for early death). In risk factor analyses, only aortic cross clamp time had statistical significance for mortality in univariate analyses. However, multivariate analyses revealed that there were no significant predictors for risk of mortality and mediastinal infection. Conclusion: Delayed sternal closure after repair of congenital cardiac disease had relatively high mortality and mediastinal infection rate. But, in patients with hemodynamic instability, postoperative bleeding and conduit compression after repair of congenital cardiac disease, delayed sternal closure may be an effective life saving method.

• Radiation Oncology Journal
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• v.15 no.2
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• pp.129-136
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• 1997

Purpose : We analyzed the survival and failure patterns of cervix cancer patients treated with irradiation alone to evaluate our treatment method and to compare with the others Methods and Materials : Two hundred and twenty cervical cancer patients, Stage IB, II A, and II B who completed the planned treatment between Mar 1987 and December 1991 were analyzed retrospectively. The Stage IB patients were restaged to the Stage IB1 and IB2 by the recently revised FIGO classification, Patients were treated with a combination of external irradiation and the intracavitary brachytherapy Determination of the tumor control was done at the time of 6 months Postirradiation. The follow-up time was ranged from 3 to 115 months and the mean was 62 months and the follow-up rate was $93.6\%$(206/220) Results : The overall 5-year survival rate of Stage IB1 (N=50), IB2(N: 15). II A(N=58), and II B(N=97) was $94\%,\;87\%,\;69\%,\;and\;56\%$. respectively. In the univariate analysis of prognostic factors, stage(0.00), initial Hg level (P=0.00), initial TA-4(tumor-associated) antigen level(p= 0.02), initial CEA level(p=0.02), barrel-shaped tumor(p=0.02), whole cervical involvement (0.00), pelvic tyrnphadenopathy(LAP) in CT(p=0.04), and Post-irradiation adiuvant chemotherapy(P=0.00) were statistically significant in survival analysis. In a while multivariate analysis showed that the stage was the most powerful Prognostic indicator and the Post-irradiation chemotherapy factor also showed the statistical significance. The overall local control rate was $81\%$ and by the stage, $100\%$ in Stage IBI, $86.7\%$ in Stage IBS, $84.5\%$ in Stage IIA, and $68.1\%$ in Stage IIB, respectively The overall tumor recurrence rate was $15.5\%$(27/174) and by the stage, $8\%$(4/50) in Stage IB1, $0\%$(0/l3) in Stage IB2, $22.4\%$(l1/49) in Stage II A, and $19.4\%$(12/62) in Stage II B, respectively. Conclusions : We obtained the similar treatment results to the other's ones in early stage cervical cancer patients. But in Stage II B, the local control rate was lower than that of the other institutes and also the survival was poorer. So it seems to be necessary to reevaluate the treatment method in advanced cervical cancer patients.

• Journal of the Korean Geographical Society
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• v.40 no.2 s.107
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• pp.221-241
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• 2005

Land Use and Land Cover Changes (LUCC) occur over a wide range of space and time scales, and involve complex natural, socio-economic, and institutional processes. Therefore, modelling and predicting LUCC demands an understanding of how various measured properties behave when considered at different scales. Understanding spatial and temporal variability of driving forces and constraints on LUCC is central to understanding the scaling issues. This paper aims to 1) assess the heterogeneity of land cover change processes over the landscape in northern Ghana, where intensification of agricultural activities has been the dominant land cover change process during the past 15 years, 2) characterise dominant land cover change mechanisms for various spatial scales, and 3) identify the optimal spatial scale for LUCC modelling in a savanna landscape. A multivariate statistical method was first applied to identify land cover change intensity (LCCI), using four time-sequenced NDVI images derived from LANDSAT scenes. Three proxy land use change predictors: distance from roads, distance from surface water bodies, and a terrain characterisation index, were regressed against the LCCI using a multi-scale hierarchical adaptive model to identify scale dependency and spatial heterogeneity of LUCC processes. High spatial associations between the LCCI and land use change predictors were mostly limited to moving windows smaller than 10$\times$10km. With increasing window size, LUCC processes within the window tend to be too diverse to establish clear trends, because changes in one part of the window are compensated elsewhere. This results in a reduced correlation between LCCI and land use change predictors at a coarser spatial extent. The spatial coverage of 5-l0km is incidentally equivalent to a village or community area in the study region. In order to reduce spatial variability of land use change processes for regional or national level LUCC modelling, we suggest that the village level is the optimal spatial investigation unit in this savanna landscape.

• Journal of Chest Surgery
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• v.43 no.2
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• pp.127-132
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• 2010

Background: Femoropopliteal artery bypss grafting is an effective form of treatment for infrainguinal artery occlusive disease in those patients who have either intermittent claudication or resting critical ischemia. The objective of this analysis was to evaluate the long-term patency of a femoropopliteal bypass graft that is classified as an above-the-knee saphenous vein graft or an above-the-knee PTFE (polytetrafluoroethylene) graft. Material and Method:From January 1998 to February 2005, 103 above-the-knee femoro-popliteal bypasses were performed on 87 patients. There were 74 male and 13 female patients with a mean age of $65.7{\pm}9.69$ (range: 31~82). The surgical indications were intermittent claudication in 65 cases (74.7%), foot ulceration in 2 cases (2.3%), foot necrosis in 10 ases (11.5%) and toe necrosis in 10 cases (11.5%). For the bypass graft, a reversed saphenous vein was used in 31 limbs and a polytetrafluoroethylene (PTFE) prosthesis was used in 72 limbs (6 mm: 27 limbs, 8 mm: 45 limbs). The perioperative risk factors were diabetes mellitus in 33 cases (37.9%), hypertension in 47 cases (54.0%), a history of ischemic heart disease in 13 cases (14.9%) and smoking in 72 cases (82.8%). Result:There were three perioperative deaths (3.4%) and seven late deaths (8.3%). Major leg amputation was necessary in 12 patients (13.8%) during the entire course of the study. The primary patency rate at 5 years for the vein grafts, the 8 mm-PTFE grafts and the 6 mm-PTFE grafts were 84.7%, 77.4% and 74.2%, respectively and the overall primary patency rate was 78.7%, and there were no significant statistical differences among the graft groups. By using multivariate analysis, the number of patent tibial arteries was determined to be a significant factor that influenced the primary graft patency rate (p<0.005), but risk factors such as diabetes mellitus, ischemic heart disease, smoking and age had no statistically significant affect on the primary graft patency rates. Conclusion: The great saphenous vein is considered the most durable conduit for infrainguinal revascularization, but the overall results of this study show that saphenous vein and PTFE grafts have comparable patency rates when used above the knee in patients with claudication or critical ischemia. The use of PTFE above the knee is a reasonable alternative for a femoro-poplitael bypass and it is associated with acceptable long term patency rates.

• Economic and Environmental Geology
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• v.38 no.3 s.172
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• pp.207-219
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• 2005

The physical and chemical characteristics of soils in a small watershed were investigated and the effect of geology and land use on soil quality were examined by using multivariate statistical methods, principal components analysis and discriminant analysis. The soil developed from andesite had finer texture and higher contents of water extractable inorganic components, clay, and mafic minerals than the soil developed from granite. It is considered that the accumulation of salts in the farmland soils indicated by electrical conductivity, contents of cations and anions and pH was caused by fertilizer input during cultivation. The low contents of organic matter in the farmland soils was due to the enhanced oxidation of organic matter by tillage and by the harvest of crops. The contents of inorganic components are increased as following order: upland > orchard > paddy field > forest. The high contents of water soluble $SO_4\;^{2-}$ of paddy soils is due to the oxidation of sulfides mineral formed during the flooding period during the air-dry and extraction. The results of principal components analysis show the difference of soil quality was controlled by geology and land use. PCI indicate the input of fertilizer, mineral weathering and ion exchange reaction by application of nitrogenous fertilizers. The results of two discriminant analyses using water extractable inorganic components and their ratios by land use were also clearly classified by discriminant function 1 and 2. In discriminant analysis by components, discriminant function 1 indicated the effect of fertilizer application and increased as following order: upland > orchard > paddy field > forest soil. The investigated and predicted data for land use from discriminant analysis showed similar results. The discriminant analysis can be used as a useful method certifying the change of land use.

• Journal of Chest Surgery
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• v.37 no.8
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• pp.691-701
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• 2004

Background: Tissue hypoxia is a characteristic of many human malignant neoplasms, and hypoxia inducible factor-1 (HIF-1) plays a pivotal role in essential adaptive response to hypoxia, and activates a signal pathway for the expression of the hypoxia-regulated genes, resulting in increased oxygen delivery or facilitating metabolic adaptation to hypoxia. Increased level of HIF-1 a has been reported in many human malignancies, but in esophageal squamous cell carcinoma, the influence of HIF-1 a on tumor biology, including neovascularization, is not still defined. Material and Method: The influence of HIF-1 a expression on angiogenic factors, correlation between the tumor proliferation and HIF-1 a expression, interaction of HIF-1 a expression and p53, and correlation between HIF-1 a expression and clinicopathological prognostic parameters were investigated, using immunohistochemical stains for HIF-1 a, VEGF, CD34, p53, and Ki-67 on 77 cases of resected esophageal squamous cell carcinoma. Result: HIF-1 a expression in cancer cells was found in 33 of 77 esophageal squamous cell carcinoma cases. The 33 cases (42.9%) showed positive stain for HIF-1 a. High HIF-1 a expression was significantly associated with several pathological parameters, such as histologic grade (p=0.032), pathological TMN stage (p=0.002), the depth of tumor invasion (p=0.022), regional lymph node metastasis (p=0.002), distant metastasis (p=0.049), and lymphatic invasion (p=0.004). High HIF-1 a expression had significant VEGF immunoreactivity (p=0.008) and Ki-67 labeling index (p<0.001), but was not correlated with microvascular density within tumors (p=0.088). The high HIF-1 a expression was correlated with aberrant p53 accumulation with a marginal significance (p=0.056). The overall 5-year survival rate was 34.9%. The survival rate of patients with a high HIF-1 a expression was worse than that of patients with low-expression tumors (log-rank test, p=0.0001). High HIF-1 a expression was independent unfavorable factors although statistical significance is marginal in multivariate analysis. Conclusion: It is suggested that (1) high HIF-1 a expression in esophageal squamous cell carcinoma is associated with tumor hypoxia, or with genetic alteration in early carcinogenesis and progressive stages, (2) high HIF-1 a expression may be associated with intratumoral neovascularization through HIF-VEGF pathway, and (3) high HIF-1 a expression is associated with poor prognosis in patients with esophageal squamous cell carcinoma and may playa role as biomarker for regional lymph node metastasis.

• Journal of Chest Surgery
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• v.32 no.9
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• pp.790-798
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• 1999

Background: As the early outcome after coronary artery bypass grafting(CABG) has been stabilized, neurologic complication has now become one of the most important morbidity. The aim of this study was to find out the risk factors associated with the neurologic complications after CABG. Material and Method: In 351 patients who underwent CABG, the incidence and features of neurologic complications, with associated perioperative risk factors, were retrospectively reviewed. Neurologic complication was defined as a new cerebral infarction confirmed by postoperative neurologic examination and radiologic studies, or delayed recovery of consciousness and orientation for more than 24 hours after the operation. Result: Neurologic complications occurred in 18 patients(5.1%), of these nine(2.6%) were diagnosed as having new cerebral infarctions(stroke). Stroke was manifested as motor paralysis in four patients, mental retardation or orientation abnormality in four, and brain death in one. Statistical analysis revealed the following variables as significant risk factors for neurologic complications by both univariate and multivariate analyses: cardiopulmonary bypass longer than 180 minutes, atheroma of the ascending aorta, carotid artery stenosis detected by Duplex sonography, and past history of cerebrovascular accident or transient ischemic attack. Age over 65 years, aortic calcification detected by simple X-ray, and intraoperative myocardial infarction were significant risk factors by univariate analysis only. Neither the severity of carotid artery stenosis nor technical modifications such as cannulation of the aortic arch or single clamp technique, which were expected to affect the inciden e of neurologic complications, had significant relationship with the incidence. Conclusion: This study confirmed the strong association between neurologic complications after CABG and atherosclerosis of the arterial system. Therefore, to minimize the incidence of neurologic complications, systematic evaluation focused on atherosclerotic lesions of the arterial system followed by adequate alteration of operative strategy is needed.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.175-190
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• 1994

In order to get fundamental information for prediction of landslide hazard, both forest and site factors affecting slope stability were investigated in many areas of active landslides. Twelve descriptors were identified and quantified to develop the prediction model by multivariate statistical analysis. The main results obtained could be summarized as follows : The main factors influencing a large scale of landslide were shown in order of precipitation, age group of forest trees, altitude, soil texture, slope gradient, position of slope, vegetation, stream order, vertical slope, bed rock, soil depth and aspect. According to partial correlation coefficient, it was shown in order of age group of forest trees, precipitation, soil texture, bed rock, slope gradient, position of slope, altitude, vertical slope, stream order, vegetation, soil depth and aspect. The main factors influencing a landslide occurrence were shown in order of age group of forest trees, altitude, soil texture, slope gradient, precipitation, vertical slope, stream order, bed rock and soil depth. Two prediction models were developed by magnitude and frequency of landslide. Particularly, a prediction method by magnitude of landslide was changed the score for the convenience of use. If the total store of the various factors mark over 9.1636, it is evaluated as a very dangerous area. The mean score of landslide and non-landslide group was 0.1977 and -0.1977, and variance was 0.1100 and 0.1250, respectively. The boundary value between the two groups related to slope stability was -0.02, and its predicted rate of discrimination was 73%. In the score range of the degree of landslide hazard based on the boundary value of discrimination, class A was 0.3132 over, class B was 0.3132 to -0.1050, class C was -0.1050 to -0.4196, class D was -0.4195 below. The rank of landslide hazard could be divided into classes A, B, C and D by the boundary value. In the number of slope, class A was 68, class B was 115, class C was 65, and class D was 52. The rate of landslide occurrence in class A and class B was shown at the hige prediction of 83%. Therefore, dangerous areas selected by the prediction method of landslide could be mapped for land-use planning and criterion of disaster district. And also, it could be applied to an administration index for disaster prevention.

• Tuberculosis and Respiratory Diseases
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• v.43 no.5
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• pp.709-719
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• 1996

Background: Surgical resection is the only way to cure non-small cell lung cancer(NSCLC) and the prognosis of NSCLC in patients who undergo a complete resection is largely influenced by the pathologic stage. After surgical resection, recurrences in distant sites is more common than local recurrences. An effective postoperative adjuvant therapy which can prevent recurrences is necessary to improve long tenn survival Although chemotherapy and radiotherapy are still the mainstay in adjuvant therapy, the benefits of such therapies are still controversial. We initiated this retrospective study to evaluate the effects of adjuvant therapies and analyze the prognostic factors for survival after curative resection. Method: From 1990 to 1995, curative resection was perfomled in 282 NSCLC patients with stage I, II, IIIa, Survival analysis of 282 patients was perfonned by Kaplan-Meier method. The prognostic factors, affecting survival of patients were analyzed by Cox regression model. Results: Squamous cell carcinoma was present in 166 patients(59%) ; adenocarcinoma in 86 pmients(30%) ; adenosquamous carcinoma in II parients(3.9%); and large cell undifferentiated carcinoma in 19 patients(7.1%). By TNM staging system, 93 patients were in stage I; 58 patients in stage II ; and 131 patients in stage rna. There were 139 postoperative recurrences which include 28 local and 111 distant failures(20.1% vs 79.9%). The five year survival rate was 50.1% in stage I ; 31.3% in stage II ; and 24.1% in stage IIIa(p <0.0001). The median survival duration was 55 months in stage I ; 27 months in stage II ; and 16 months in stage rna. Among 131 patients with stage rna, the median survival duration was 19 months for 81 patients who received postoperative adjuvant chemotherapy only or cherne-radiotherapy and 14 months for the other 50 patients who received surgery only or surgery with adjuvant radiotherapy(p=0.2982). Among 131 patients with stage IIIa, the median disease free survival duration was 16 months for 21 patients who received postop. adjuvant chemotherapy only and 4 months for 11 patients who received surgery only(p=0.0494). In 131 patients with stage IIIa, 92 cases were in N2 stage. The five year survival rate of the 92 patients with N2 was 25% and their median survival duration was 15 months. The median survival duration in patients with N2 stage was 18 months for those 62 patients who received adjuvant chemotherapy and 14 months for the other 30 patients who did not(p=0.3988). The median survival duration was 16 months for those 66 patients who received irradiation and 14 months for the other 26 patients who did not(p=0.6588). We performed multivariate analysis to identify the factors affecting prognosis after complete surgical resection, using the Cox multiple regression model. Only age(p=0.0093) and the pathologic stage(p<0.0001) were significam prognostic indicators. Conclusion: The age and pathologic stage of the NSCLC parients are the significant prognostic factors in our study. Disease free survival duration was prolonged with statistical significance in patients who received postoperative adjuvant chemotherapy but overall survival duration was not affected according to adjuvant therapy after surgical resection.