PURPOSE: In clinical studies, patients may experience several types of events during follow up under the competing risks (CR) framework. Patients are often classified into low- and high-risk groups based on prognostic factors. We propose a method to determine an optimal cutpoint value for prognostic factors on censored outcomes in the presence of CR. MATERIALS AND METHODS: We applied our method to data collected in a study of lung cancer patients. From September 1, 1991 to December 31, 2005, 758 lung cancer patients received tumor removal surgery at Samsung Medical Center in Korea. The proposed statistic converges in distribution to that of the supremum of a standardized Brownian bridge. To overcome the conservativeness of the test based on an approximation of the asymptotic distribution, we also propose a permutation test based on permuted samples. RESULTS: Most cases considered in our simulation studies showed that the permutation-based test satisfied a significance level of 0.05, while the approximation-based test was very conservative: the powers of the former were larger than those of the latter. The optimal cutpoint value for tumor size (unit: cm) prior to surgery for classifying patients into two groups (low and high risks for relapse) was found to be 1.8, with decent significance reflected as p values less than 0.001. CONCLUSION: The cutpoint estimator based on the maximally selected linear rank statistic was reasonable in terms of bias and standard deviation in the CR framework. The permutation-based test well satisfied type I error probability and provided higher power than the approximation-based test.
Bias (Epidemiology) ; Follow-Up Studies ; Humans ; Korea ; Lung Neoplasms ; Lung ; Methods

BACKGROUND AND OBJECTIVES: Long-term right ventricular (RV) apex pacing has been associated with left ventricular (LV) systolic dysfunction. However, pacing in the RV outflow tract (RVOT) is associated with a narrower QRS duration and may have a more normal LV activation in comparison to RV apical (RVA) pacing. We hypothesized that RVOT pacing is associated with less mechanical dyssynchrony compared to RVA pacing and that it also more closely resembles mechanical activation in normal controls with a narrow QRS. SUBJECTS AND METHODS: We studied 9 patients with RV pacing, 9 with left bundle branch block (LBBB), and 15 normal controls with a narrow QRS. In the RV pacing group, we paced from the RVA and RVOT. At the end of each pacing train, we obtained echocardiographic images in the apical 4- and 2-chamber views and obtained the following parameters: the compression/expansion crossover point (CEP) for myocardial strain and the time from QRS onset to the CEP in the strain image. The degree of dyssynchrony was evaluated using the dispersion and standard deviation of CEP times in 12 segments of the LV. RESULTS: Significant dyssynchrony was observed in the RVOT pacing group compared to the group with normal QRS. No significant difference was observed in LV mechanical dyssynchrony among the RVOT pacing, RVA pacing, and LBBB groups. CONCLUSION: RVOT pacing is associated with significant LV dyssynchrony. Although the RVOT has been recommended as an alternative site for pacing, this approach may have adverse effects on long-term LV function.
Bundle-Branch Block ; Heart Ventricles ; Humans ; Sprains and Strains

Purpose: Reliable landmarks of ankle syndesmosis change in various positions is important for managing ankle injury. The purpose of our study was to investigate and compare radiographic landmarks of normal ankle in various positions. Methods: The study involved both ankle radiographs of 30 subjects (15 males, 15 females) without clinical or radiographic abnormality. Tibiofibular clear space (TFCS) and tibiofibular overlap (TFO) were measured on anteroposterior (AP) and mortise radiographs in non-standing (NS) and standing (S) neutral and dorsiflexion 10° (DF10) and 20° (DF20). The radiographic measurements were used to calculate means, standard deviations, and intra- and interobserver reliabilities, and compare TFCS and TFO in various positions and genders. Results: On the AP view, the mean TFCS in NS, S, DF10, and DF20 positions were 4.00±0.97, 4.00±0.83, 4.35±0.95, and 4.45±0.89 mm and the mean TFO on the same positions were 6.58±2.27, 4.27±1.90, 3.44±1.96, and 2.38±1.91 mm. On the mortise view, the mean TFCS in NS, DF10, and DF20 positions were 3.62±0.88, 4.08±0.86, and 3.88±0.97 mm and the mean TFO on the same positions were 3.57±2.13, 2.31±1.77, and 3.57±2.14 mm. The reliabilities in all positions except TFCS on some positions were excellent. No measurement was significantly different between females and males except TFO in NS on mortise view (p=0.006) and DF10 on AP view (p=0.032). Conclusion Increase of TFCS and decrease of TFO on AP view reflects syndesmosis change from NS to DF20 on standing. Clinically, the effect of weight-bearing and reliability of TFO should be considered.

BACKGROUND: Although thymomas are relatively common mediastinal tumors, to date not only has a universal system of pathologic classification not been established but neither has a clearly defined predictable relationship between treatment and prognosis been made. Recently, a new guideline for classification was reported by WHO, and efforts, based on this work, have been made to better define the relationship between treatment and prognostic outcome. In the present study a comparative analysis between the WHO classification and Masaoka stage system with the clinical disease pattern was conducted. MATERIAL AND METHOD: A total of 98 patients undergoing complete resection for mediastinal thymoma between Juanuary 1993 and June 2003 were included in the present study. The male female ratio was 48:50 and the mean age at operation was 49.6+/-13.9 years. A retrospective analytic comparison studying the relationship between the WHO classification and the Masaoka stage system with the clinical disease pattern of thymoma was conducted. Pathologic slide specimens were carefully examined, details of postoperative treatment were documented, and a relationship with the prognostic outcome and recurrence was studied. RESULT: There were 7 patients in type A according to the WHO system of classification, 14 in AB, 28 in B1, 23 in B2, 18 in B3, and 9 in type C. The study of the relationship between the Masaoka stage and WHO classification system showed 4 patients to be in WHO system type A, 7 in type AB, 22 in B1, 17 in B2, and 3 in type B3 among 53 (54%) patients shown to be in Masaoka stage I. Among 28 (28.5%) patients in Masaoka stage II system, there were 2 patients in type A, 7 in AB, 4 in B1, 2 in B2, 8 in B3, and 5 in type C. Among 15 (15.3%) in Masaoka stage III, there were 1 patient in type B1, 3 in B2, 7 in B3, and 4 in type C. Finally, among 2 (2%) patients found to be in Masaoka stage IV there was 1 patient in type B1, and 1 in type B2. The mean follow up duration was 28+/-6.8 months. There were 3 deaths in the entire series of which 2 were in type B2 (Masaoka stages III and IV), and 1 was in type C (Masaoka stage II). Of the patients that experienced relapse, 6 patients remain alive of which 2 were in type B2 (Masaoka III), 2 in type B3 (Masaoka I and III) and 2 in type C (Masaoka stage II). The 5 year survival rate by the Kaplan-Meier method was 90% for those in type B2 WHO classification system, 87.5% for type C. The 5 year freedom from recurrence rate was 80.7% for those in WHO type B2, 81.6% for those in type B3, and 50% for those in type C. By the Log-Rank method, a statistically significant correlation between survival and recurrence was found with the WHO system of classification (p<0.05). An analysis of the relationship between the WHO classification and Masaoka stage system using the Spearman correction method, showed a slope=0.401 (p=0.023), showing a close correlation. CONCLUSION: As type C of the WHO classification system is associated with a high postoperative mortality and recurrence rate, aggressive treatment postoperatively and meticulous follow up are warranted. The WHO classification and Masaoka stage system were found to have a close relationship with each other and either the WHO classification method or the Masaoka stage system may be used as a predict prognostic outcome of Thymoma.
Classification* ; Female ; Follow-Up Studies ; Freedom ; Humans ; Male ; Mortality ; Neoplasm Staging ; Prognosis ; Recurrence ; Retrospective Studies ; Survival Rate ; Thymoma*

No abstract available.
Corpus Callosum* ; Diffusion* ; Hypoxia, Brain*

BACKGROUND AND OBJECTIVES: Tympanic membrane perforation is an important clinical problem found in various populations of the world. In large number of cases, acute traumatic perforations heal spontaneously, and in the healing process, stem cells appear to play an important role. However, no studies have been reported regarding somatic stem cells in the tympanic membrane. Herein, we tried to show that guinea pig's tympanic membrane contains cells that display the characteristic features of stem cells. MATERIALS AND METHOD: The tympanic membrane was obtained from the guinea pig. The cells were cultured in a medium with epidermal growth factor (EGF) and fibroblast growth factor (FGF). Proliferating cells were checked with stem cell markers, bromodeoxyuridine (BrdU) and nestin. Differentiated cells from stem cells are checked with betaIII tubulin and S-100. RESULTS: We observed that some of the cultured cells from the tympanic membrane were stained with both stem cell markers, BrdU and nestin. And we observed that these cells differentiated into neuron and gilal cells, which expressed betaIII tubulin and S-100, respectively. CONCLUSION: These results suggest that the tympanic membrane of guinea pigs may have neural stem cells. Further study is needed for finding the origin of stem cells.
Adult ; Adult Stem Cells ; Animals ; Bromodeoxyuridine ; Cells, Cultured ; Epidermal Growth Factor ; Fibroblast Growth Factors ; Guinea ; Guinea Pigs ; Humans ; Intermediate Filament Proteins ; Nerve Tissue Proteins ; Neural Stem Cells ; Neurons ; Stem Cells ; Tubulin ; Tympanic Membrane ; Tympanic Membrane Perforation

Approximately 15% of patients with frontotemporal dementia (FTD) have co-occurring motor neuron disease (MND). FTD-MND cases have frontotemporal lobar degeneration (FTLD)-transactive response DNA-binding protein (TDP) pathology, which is divided into four subtypes (types A, B, C, and D) based on the morphological appearance, cellular location, and distribution of the abnormal TDP inclusions and dystrophic neurites. We report a patient with FTD-MND whose pathological diagnosis was FTLD-TDP type B. This is the first documented autopsy-confirmed case of FTD-MND in Korea.
Autopsy* ; Diagnosis ; Frontotemporal Dementia* ; Frontotemporal Lobar Degeneration ; Humans ; Korea ; Motor Neuron Disease* ; Motor Neurons* ; Neurites ; Pathology

Approximately 15% of patients with frontotemporal dementia (FTD) have co-occurring motor neuron disease (MND). FTD-MND cases have frontotemporal lobar degeneration (FTLD)-transactive response DNA-binding protein (TDP) pathology, which is divided into four subtypes (types A, B, C, and D) based on the morphological appearance, cellular location, and distribution of the abnormal TDP inclusions and dystrophic neurites. We report a patient with FTD-MND whose pathological diagnosis was FTLD-TDP type B. This is the first documented autopsy-confirmed case of FTD-MND in Korea.
Autopsy* ; Diagnosis ; Frontotemporal Dementia* ; Frontotemporal Lobar Degeneration ; Humans ; Korea ; Motor Neuron Disease* ; Motor Neurons* ; Neurites ; Pathology

A 63-year-old man presented with a 1.5-year history of progressive personality changes. Clinical evaluations revealed severe frontal dysfunction and bilateral frontal atrophy/glucose hypometabolism. He was diagnosed as probable behavioral variant frontotemporal dementia. He continued to decline, and died at the age of 66. At autopsy, numerous tau-positive gilial threads and coiled bodies were observed in the white matter. Tau-positive astrocytic plaques and neuronal cytoplasmic inclusions were also seen in cerebral cortices, which were compatible with corticobasal degeneration.
Autopsy* ; Cerebral Cortex ; Coiled Bodies ; Frontotemporal Dementia* ; Humans ; Inclusion Bodies ; Middle Aged ; Neurons ; Pathology*

A 63-year-old man presented with a 1.5-year history of progressive personality changes. Clinical evaluations revealed severe frontal dysfunction and bilateral frontal atrophy/glucose hypometabolism. He was diagnosed as probable behavioral variant frontotemporal dementia. He continued to decline, and died at the age of 66. At autopsy, numerous tau-positive gilial threads and coiled bodies were observed in the white matter. Tau-positive astrocytic plaques and neuronal cytoplasmic inclusions were also seen in cerebral cortices, which were compatible with corticobasal degeneration.
Autopsy* ; Cerebral Cortex ; Coiled Bodies ; Frontotemporal Dementia* ; Humans ; Inclusion Bodies ; Middle Aged ; Neurons ; Pathology*