OBJECTIVES: In large-scale field trials, randomization by cluster is frequently used because of the administrative convenience, a desire to reduce the effect of treatment contamination, and the need to avoid ethical issues that might otherwise arise. Cluster randomization trials are experiments in which intact social unit, e.g., families, schools, cities, rather than independent individuals are randomly allocated to intervention groups. The positive correlation among responses of subjects from the same cluster is in matter in cluster randomization. This thesis is to compare the results of three randomization methods by standard error of estimator of treatment effect. METHODS: We simulated cholesterol data varing the size of the cluster and the level of the correlation in clusters and analyzed the effect of cholesterol-lowering agent. RESULTS: In intra-cluster randomization the standard error of the estimator of treatment effect is smallest relative to that in inter-cluster randomization and that in individual randomization. CONCLUSIONS: Intra-cluster randomization is the most efficient in its standard error of estimator of treatment effect but other factor should be considered when selecting a specific randomization method.
Cholesterol ; Ethics ; Humans ; Random Allocation*

PURPOSE: Urinary red blood cell morphology has been used to localize the site of hematuria in the urinary tract. But the pathologic mechanism for dysmorphic urinary red blood cells remains undefned. Our study was undertaken to investigate the mechanism of dysmorphic urinary RBCs in glomerular hematuria. We have attempted to reproduce in vitro the changes that occur in red cell morphology during passage through the renal tubule and to elucidate the role of urinary composition in determining morphology. METHODS: We examined a number of urinary samples under bright f eld microscopes with Wright's stain. 1) One drop of fresh venous blood was added to 1 ml experimental fluid, allowed to stand for 5 min and then assessed. The experimental fluids used were NaCl solutions in which the sodium concentration varied among 40 and 400mmol/L and similar saline solutions to which KCl(10, 50mmol/L), CaCl2(0.5, 2mmol/L), Urea(100, 400mmol/L) and pH(4, 8) had been added. We examined the RBC morphology in these solution. 2) In order to simulate passage of RBCs through the renal tubule, RBCs were initially suspended for 5 min in hypertonic solutions(NaCl 200mmol/L+Urea 70mmol/L+Urea 1000mmol/L). The RBCs were separated by centrifuging at 500rpm for 2 min in conical tubes, the supernatant was discarded and the RBCs washed and resuspended in a hypotonic solution(NaCl 60mmol/L) for 5 min. We added two urines(610mOsm/Kg H2O) to these solutions and then examined the RBCs morphology. RESULTS: The results were as follows; 1) Anisocytosis and hypochromia were found in NaCl 60mmol/L and 75mmol/L solutions and crenated RBC was found in Nacl 400mmol/L solution. But addition of potassium, calcium or urea and variation of the pH had no effect on red cell morphology. 2) when exposed to hypotonic solution, which simulated tubular condition(NaCl 60mmol/L), the RBCs became anisocytotic and hypochromic. These two features were particularly marked if cells were transferred to concentrated urine(610mOsm/kg H2O). CONCLUSIONS: It is evident that a hypotonic tubular condition is hostile for red cells and may be primarily responsible for hy0pochromia and anisocytosis of RBCs. Although two characteristic features of dysmorphism can be reproduced in vitro, a the bizarre deformity cannot be observed. Therefore passage of red cells through the hypotonic tubular segment alone does not account for the typical deformity. Because dilute urine specimens give a false impression by selective lysis of dysmorphic cells, concentrated urine is suitable for analysis of red cell morphology.
Calcium ; Congenital Abnormalities ; Erythrocytes ; Hematuria* ; Hydrogen-Ion Concentration ; Potassium ; Sodium ; Urea ; Urinary Tract

Myocardial bridging is defined that short segments of coronary artery descend into the myocardium for a variable distance and each systolic contraction of these fibers can cause narrowing of the artery. Systolic narrow-ing may rarely be caused by connective tissue such as fibrous band. Myocardial ischemia, infarction and sudden death may be seen in some patients with myocardial bridging. Myocardial infarction in association with isolated myocardial bridges with systolic narrowing is uncommon. We report a case of Q wave myocardial infarction in a patient with angiographic systolic narrowing at the middle segment left anterior descending coronary artery which was caused by fibrous band.
Arteries ; Connective Tissue ; Coronary Vessels ; Death, Sudden ; Humans ; Infarction ; Myocardial Bridging* ; Myocardial Infarction* ; Myocardial Ischemia ; Myocardium

Left atrial thrombus is frequently associated with rheumatic mitral valvular heart disease. Left atrial thrombus is usually attached to the atrial wall, but rarely it is freely floating in the cavity. In that case the patient may present with the symptoms of acute hemodynamic decompensation due to the so-called "hole-in-one" effect or multiple systemic embolism. We report a case of multiple systemic embolism associated with left atrial free-floating ball thrombus in mitral valvular heart disease.
Echocardiography ; Embolism* ; Heart Valve Diseases ; Hemodynamics ; Humans ; Thrombosis*

No abstract available.
Morphine* ; Respiration, Artificial* ; Weaning*

PURPOSE: A telomerase reverse transcriptase (TERT) promoter mutation was identified in thyroid cancer. This TERT promoter mutation is thought to be a prognostic molecular marker, because its association with tumor aggressiveness, persistence/recurrence, and disease-specific mortality in papillary thyroid carcinoma (PTC) has been reported. In this study, we attempted to determine whether the impact of the TERT promoter mutation on PTC persistence/recurrence is independent of clinicopathological parameters. MATERIALS AND METHODS: Using propensity score matching, 39 patients with PTC persistence or recurrence were matched with 35 patients without persistence or recurrence, with a similar age, sex, tumor size, multifocality, bilaterality, extrathyroidal extension, and lymph node metastasis. The TERT promoter and the BRAF V600E mutations were identified from PTC samples. RESULTS: The TERT promoter mutation was detected in 18% of PTC patients (13/74). No significant difference in the frequency of the TERT promoter mutation was observed between the persistence/recurrence group and the non-recurrence group. CONCLUSION: These results suggest that the prognostic implications of the TERT promoter mutation are dependent on clinicopathological parameters.
Humans ; Lymph Nodes ; Mortality ; Neoplasm Metastasis ; Propensity Score ; Recurrence ; Telomerase ; Thyroid Gland* ; Thyroid Neoplasms*

The mental health of medical students deserves attention because the problems in students may negatively influence learning ability and create consequences for later adjustment to doctor's role. The purpose of this study is to understand the stress, copying, self-esteem and subjective general well-being of medical students and compare them with other students group (students of law, science and humanities). The results was as follows : First, medical students did not report more stress but they use less copying strategy than other students group. Second, there was no differences in stress, copying, self-esteem and general well-being between high and low academic achievement group in medical students. Futhermore, study-related stress had more close relationship with self-esteem, general well-being. Third, the preparatory course students showed lower score in general well-being, especially health, cheerful-depressive mood domain. These results imply that mental health promotion programmes focused in guiding adjustment for the preparatory course students are helpful. And psychiatric, academic counseling should be made available to them. It can lead to an improvement in our health care delivery system. The need of additional longitudinal research is discussed.
Counseling ; Delivery of Health Care ; Humans ; Jurisprudence ; Learning ; Mental Health ; Students, Medical*

PURPOSE: To determine optimal window settings for measuring the inner diameter of the trachea and both mainbronchi by spiral CT. MATERIALS AND METHODS: Chest PA radiography and spiral CT scanning were performed in ten healthy adult volunteers. Three dimensional images were reconstructed (minimal threshold value : -1000HU ; maximal threshold value : from -200 to -900HU, of 50HU intervals) to measure the inner diameter of the trachea and both main bronchi. The results of 3D spiral CT were compared with those of chest radiography. RESULTS: The inner diameters of the trachea, right main bronchus, left main bronchus-I (1cm below the tracheal carina) and left mainbronchus-II (2cm below the tracheal carina) measured by chest radiograph and 3D spiral CT were not significantly different at maximal threshold values of -400 ~ -550HU, -450 ~ -550HU, -450 ~ -600HU and -500 ~ -600HU, respectively (p>0.05). The differences in the results of the two series were statistically significant at other threshold values however (p<0.05). CONCLUSION: We determined optimal window settings for measuring the inner diameter of the trachea and both main bronchi by spiral CT. The optimal maximal threshold values were somewhat different according to measured sites of the trachea and both main bronchi.
Adult ; Bronchi ; Humans ; Radiography ; Radiography, Thoracic ; Thorax ; Tomography, Spiral Computed* ; Trachea ; Volunteers

BACKGROUND: The literature on variations of rib is limited. Very little has been written in the radiological journal of this country on the subject. It seemed of interest to investigate the nature and incidence of congenital variations in a series of routine chest roentgenograms. The topic of rib variations has not been covered extensively in the radiological journals in Korea. This has presented an opportunity to investigate the nature, type, shape and incidences of congenital rib variations in normal Korean adults from a series of routine roentgenograms. METHODS: Chest radiographs of 5,000 adults (,) who visited our hospital for a routine check-up or for employment physical examinations from January 1996 to September 1998, were consecutively reviewed. The sex distribution consisted of 2,827 male males and 2,173 females (ratio of 1.3:1) with the age range between 19 and 65 years (mean age: 34.6 years). The chest PAs was were analyzed for the presence, type, location, and shape of the rib variations (.) From this data, and we the incidence of each type of variations was calculated. RESULTS: Seventy-six of the 5000 adults (1.52%), 63 male (2.23%) and 13 female (0.6%), showed 88 cases of rib variation (Table 1). Bifid rib (n=35) was the The most common variation was the bifid rib (n=35), followed by hypoplasia of the rib (n=22), flaring of the rib (n=18), bridging of the ribs (n=7), cervical ribs (n=3), and fusion of between ribs (n=3) (Table 2). (New paragraph)Bifid The bifid rib (Table 1) was found most frequent in the right fourth rib (12/35, 34.3%), followed by the left fifth rib (6/35, 17.1%) and right third rib (6/35, 17.1%). Hypoplasia of the rib was common in first rib (20/22, 90.9%). Flaring of the rib was common at fourth rib (8/18. 44.4%, right and left combined) (,) and bridging between ribs was common between first and second rib (3/7, 42.9%). CONCLUSION: The percentage of incidence of rib variations in adults was 1.52%. Bifid rib was the most common variation, followed by hypoplasia, flaring, bridging, cervical rib, and fusion of ribs(,) in decreasing order.
Adult ; Cervical Rib ; Employment ; Female ; Humans ; Incidence* ; Korea ; Male ; Physical Examination ; Radiography ; Radiography, Thoracic* ; Ribs* ; Sex Distribution ; Thorax*

Uterus didelphys with unilateral obstructed hemivagina is indeed a very rare congenital anomaly due to M llerian duct malformation. The most common clinical presentation is pelvic pain and dysmenorrhea shortly after menarche, in associated with the finding of a vaginal or pelvic mass. An accurate and prompt diagnosis is of importance to permit treatment and to assure the future fertility of the patient. The simple and adequate treatment of the condition is incision of the obstructed vaginal septum providing adequate drainage of the retained blood. We report a case of uterus didelphys with obstructed hemivagina with brief review of the literature.
Diagnosis ; Drainage ; Dysmenorrhea ; Female ; Fertility ; Humans ; Menarche ; Pelvic Pain ; Uterus*